Life Extension Magazine®

Issue: Mar 2014

Zinc

Mitofusin-2 determines mitochondrial network architecture and mitochondrial metabolism. A novel regulatory mechanism altered in obesity.

In many cells and specially in muscle, mitochondria form elongated filaments or a branched reticulum. We show that Mfn2 (mitofusin 2), a mitochondrial membrane protein that participates in mitochondrial fusion in mammalian cells, is induced during myogenesis and contributes to the maintenance and operation of the mitochondrial network. Repression of Mfn2 caused morphological and functional fragmentation of the mitochondrial network into independent clusters. Concomitantly, repression of Mfn2 reduced glucose oxidation, mitochondrial membrane potential, cell respiration, and mitochondrial proton leak. We also show that the Mfn2-dependent mechanism of mitochondrial control is disturbed in obesity by reduced Mfn2 expression. In all, our data indicate that Mfn2 expression is crucial in mitochondrial metabolism through the maintenance of the mitochondrial network architecture, and reduced Mfn2 expression may explain some of the metabolic alterations associated with obesity.

J Biol Chem. 2003 May 9;278(19):17190-7

Expression of Mfn2, the Charcot-Marie-Tooth neuropathy type 2A gene, in human skeletal muscle: effects of type 2 diabetes, obesity, weight loss, and the regulatory role of tumor necrosis factor alpha and interleukin-6.

The primary gene mutated in Charcot-Marie-Tooth type 2A is mitofusin-2 (Mfn2). Mfn2 encodes a mitochondrial protein that participates in the maintenance of the mitochondrial network and that regulates mitochondrial metabolism and intracellular signaling. The potential for regulation of human Mfn2 gene expression in vivo is largely unknown. Based on the presence of mitochondrial dysfunction in insulin-resistant conditions, we have examined whether Mfn2 expression is dysregulated in skeletal muscle from obese or nonobese type 2 diabetic subjects, whether muscle Mfn2 expression is regulated by body weight loss, and the potential regulatory role of tumor necrosis factor (TNF)alpha or interleukin-6. We show that mRNA concentration of Mfn2 is decreased in skeletal muscle from both male and female obese subjects. Muscle Mfn2 expression was also reduced in lean or in obese type 2 diabetic patients. There was a strong negative correlation between the Mfn2 expression and the BMI in nondiabetic and type 2 diabetic subjects. A positive correlation between the Mfn2 expression and the insulin sensitivity was also detected in nondiabetic and type 2 diabetic subjects. To determine the effect of weight loss on Mfn2 mRNA expression, six morbidly obese subjects were subjected to weight loss by bilio-pancreatic diversion. Mean expression of muscle Mfn2 mRNA increased threefold after reduction in body weight, and a positive correlation between muscle Mfn2 expression and insulin sensitivity was again detected. In vitro experiments revealed an inhibitory effect of TNFalpha or interleukin-6 on Mfn2 expression in cultured cells. We conclude that body weight loss upregulates the expression of Mfn2 mRNA in skeletal muscle of obese humans, type 2 diabetes downregulates the expression of Mfn2 mRNA in skeletal muscle, Mfn2 expression in skeletal muscle is directly proportional to insulin sensitivity and is inversely proportional to the BMI, TNFalpha and interleukin-6 downregulate Mfn2 expression and may participate in the dysregulation of Mfn2 expression in obesity or type 2 diabetes, and the in vivo modulation of Mfn2 mRNA levels is an additional level of regulation for the control of muscle metabolism and could provide a molecular mechanism for alterations in mitochondrial function in obesity or type 2 diabetes.

Diabetes. 2005 Sep;54(9):2685-93

Mitofusin 2 (Mfn2) links mitochondrial and endoplasmic reticulum function with insulin signaling and is essential for normal glucose homeostasis.

Mitochondria are dynamic organelles that play a key role in energy conversion. Optimal mitochondrial function is ensured by a quality-control system tightly coupled to fusion and fission. In this connection, mitofusin 2 (Mfn2) participates in mitochondrial fusion and undergoes repression in muscle from obese or type 2 diabetic patients. Here, we provide in vivo evidence that Mfn2 plays an essential role in metabolic homeostasis. Liver-specific ablation of Mfn2 in mice led to numerous metabolic abnormalities, characterized by glucose intolerance and enhanced hepatic gluconeogenesis. Mfn2 deficiency impaired insulin signaling in liver and muscle. Furthermore, Mfn2 deficiency was associated with endoplasmic reticulum stress, enhanced hydrogen peroxide concentration, altered reactive oxygen species handling, and active JNK. Chemical chaperones or the antioxidant N-acetylcysteine ameliorated glucose tolerance and insulin signaling in liver-specific Mfn2 KO mice. This study provides an important description of a unique unexpected role of Mfn2 coordinating mitochondria and endoplasmic reticulum function, leading to modulation of insulin signaling and glucose homeostasis in vivo.

Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):5523-8

Subjects with early-onset type 2 diabetes show defective activation of the skeletal muscle PGC-1{alpha}/Mitofusin-2 regulatory pathway in response to physical activity.

OBJECTIVE Type 2 diabetes is associated with insulin resistance and skeletal muscle mitochondrial dysfunction. We have found that subjects with early-onset type 2 diabetes show incapacity to increase Vo(2max) in response to chronic exercise. This suggests a defect in muscle mitochondrial response to exercise. Here, we have explored the nature of the mechanisms involved. RESEARCH DESIGN AND METHODS Muscle biopsies were collected from young type 2 diabetic subjects and obese control subjects before and after acute or chronic exercise protocols, and the expression of genes and/or proteins relevant to mitochondrial function was measured. In particular, the regulatory pathway peroxisome proliferator-activated receptor gamma coactivator (PGC)-1alpha/mitofusin-2 (Mfn2) was analyzed. RESULTS At baseline, subjects with diabetes showed reduced expression (by 26%) of the mitochondrial fusion protein Mfn2 and a 39% reduction of the alpha-subunit of ATP synthase. Porin expression was unchanged, consistent with normal mitochondrial mass. Chronic exercise led to a 2.8-fold increase in Mfn2, as well as increases in porin, and the alpha-subunit of ATP synthase in muscle from control subjects. However, Mfn2 was unchanged after chronic exercise in individuals with diabetes, whereas porin and alpha-subunit of ATP synthase were increased. Acute exercise caused a fourfold increase in PGC-1alpha expression in muscle from control subjects but not in subjects with diabetes. CONCLUSIONS Our results demonstrate alterations in the regulatory pathway that controls PGC-1alpha expression and induction of Mfn2 in muscle from patients with early-onset type 2 diabetes. Patients with early-onset type 2 diabetes display abnormalities in the exercise-dependent pathway that regulates the expression of PGC-1alpha and Mfn2.

Diabetes Care. 2010 Mar;33(3):645-51

Dynamics of fat cell turnover in humans.

Obesity is increasing in an epidemic manner in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells (adipocytes) is thought to be most important. Here we show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese individuals, even after marked weight loss, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analysing the integration of 14C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in early onset obesity, suggesting a tight regulation of fat cell number in this condition during adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.

Nature. 2008 Jun 5;453(7196):783-7

Mitophagy in neurodegeneration and aging.

Macroautophagy is a cellular catabolic process that involves the sequestration of cytoplasmic constituents into double-membrane vesicles known as autophagosomes, which subsequently fuse with lysosomes, where they deliver their cargo for degradation. The main physiological role of autophagy is to recycle intracellular components, under conditions of nutrient deprivation, so as to supply cells with vital materials and energy. Selective autophagy also takes place in nutrient-rich conditions to rid the cell of damaged organelles or protein aggregates that would otherwise compromise cell viability. Mitophagy is a selective type of autophagy, whereby damaged or superfluous mitochondria are eliminated to maintain proper mitochondrial numbers and quality control. While mitophagy shares key regulatory factors with the general macroautophagy pathway, it also involves distinct steps, specific for mitochondrial elimination. Recent findings indicate that parkin and the phosphatase and tensin homolog-induced putative kinase protein 1 (PINK1), which have been implicated in the pathogenesis of neurodegenerative diseases such as Parkinson’s disease, also regulate mitophagy and function to maintain mitochondrial homeostasis. Here, we survey the molecular mechanisms that govern the process of mitophagy and discuss its involvement in the onset and progression of neurodegenerative diseases during aging.

Front Genet. 2012 Dec 19;3:297

Autophagy and ageing: insights from invertebrate model organisms.

Ageing in diverse species ranging from yeast to humans is associated with the gradual, lifelong accumulation of molecular and cellular damage. Autophagy, a conserved lysosomal, self-destructive process involved in protein and organelle degradation, plays an essential role in both cellular and whole-animal homeostasis. Accumulating evidence now indicates that autophagic degradation declines with age and this gradual reduction of autophagy might have a causative role in the functional deterioration of biological systems during ageing. Indeed, loss of autophagy gene function significantly influences longevity. Moreover, genetic or pharmacological manipulations that extend lifespan in model organisms often activate autophagy. Interestingly, conserved signalling pathways and environmental factors that regulate ageing, such as the insulin/IGF-1 signalling pathway and oxidative stress response pathways converge on autophagy. In this article, we survey recent findings in invertebrates that contribute to advance our understanding of the molecular links between autophagy and the regulation of ageing. In addition, we consider related mechanisms in other organisms and discuss their similarities and idiosyncratic features in a comparative manner.

Ageing Res Rev. 2013 Jan;12(1):413-28

Spermidine and resveratrol induce autophagy by distinct pathways converging on the acetylproteome.

Autophagy protects organelles, cells, and organisms against several stress conditions. Induction of autophagy by resveratrol requires the nicotinamide adenine dinucleotide-dependent deacetylase sirtuin 1 (SIRT1). In this paper, we show that the acetylase inhibitor spermidine stimulates autophagy independent of SIRT1 in human and yeast cells as well as in nematodes. Although resveratrol and spermidine ignite autophagy through distinct mechanisms, these compounds stimulate convergent pathways that culminate in concordant modifications of the acetylproteome. Both agents favor convergent deacetylation and acetylation reactions in the cytosol and in the nucleus, respectively. Both resveratrol and spermidine were able to induce autophagy in cytoplasts (enucleated cells). Moreover, a cytoplasm-restricted mutant of SIRT1 could stimulate autophagy, suggesting that cytoplasmic deacetylation reactions dictate the autophagic cascade. At doses at which neither resveratrol nor spermidine stimulated autophagy alone, these agents synergistically induced autophagy. Altogether, these data underscore the importance of an autophagy regulatory network of antagonistic deacetylases and acetylases that can be pharmacologically manipulated.

J Cell Biol. 2011 Feb 21;192(4):615-29

Spermidine promotes stress resistance in Drosophila melanogaster through autophagy-dependent and -independent pathways.

The naturally occurring polyamine spermidine (Spd) has recently been shown to promote longevity across species in an autophagy-dependent manner. Here, we demonstrate that Spd improves both survival and locomotor activity of the fruit fly Drosophila melanogaster upon exposure to the superoxide generator and neurotoxic agent paraquat. Although survival to a high paraquat concentration (20 mM) was specifically increased in female flies only, locomotor activity and survival could be rescued in both male and female animals when exposed to lower paraquat levels (5 mM). These effects are dependent on the autophagic machinery, as Spd failed to confer resistance to paraquat-induced toxicity and locomotor impairment in flies deleted for the essential autophagic regulator ATG7 (autophagy-related gene 7). Spd treatment did also protect against mild doses of another oxidative stressor, hydrogen peroxide, but in this case in an autophagy-independent manner. Altogether, this study establishes that the protective effects of Spd can be exerted through different pathways that depending on the oxidative stress scenario do or do not involve autophagy.

Cell Death Dis. 2012 Oct 11;3:e401

Mitochondrial telomerase reverse transcriptase binds to and protects mitochondrial DNA and function from damage.

OBJECTIVE: The enzyme telomerase and its catalytic subunit the telomerase reverse transcriptase (TERT) are important for maintenance of telomere length in the nucleus. Recent studies provided evidence for a mitochondrial localization of TERT. Therefore, we investigated the exact localization of TERT within the mitochondria and its function. METHODS AND RESULTS: Here, we demonstrate that TERT is localized in the matrix of the mitochondria. TERT binds to mitochondrial DNA at the coding regions for ND1 and ND2. Binding of TERT to mitochondrial DNA protects against ethidium bromide-induced damage. TERT increases overall respiratory chain activity, which is most pronounced at complex I and dependent on the reverse transcriptase activity of the enzyme. Moreover, mitochondrial reactive oxygen species are increased after genetic ablation of TERT by shRNA. Mitochondrially targeted TERT and not wild-type TERT revealed the most prominent protective effect on H(2)O(2)-induced apoptosis. Lung fibroblasts from 6-month-old TERT(-/-) mice (F2 generation) showed increased sensitivity toward UVB radiation and heart mitochondria exhibited significantly reduced respiratory chain activity already under basal conditions, demonstrating the protective function of TERT in vivo. CONCLUSIONS: Mitochondrial TERT exerts a novel protective function by binding to mitochondrial DNA, increasing respiratory chain activity and protecting against oxidative stress-induced damage.

Arterioscler Thromb Vasc Biol. 2009 Jun;29(6):929-35

Anti-inflammatory and immunomodulatory effects of paeonia lactiflora pall., a traditional chinese herbal medicine.

In China, Korea, and Japan, a decoction of the dried root without bark of Paeonia lactiflora Pall. has been used in the treatment of rheumatoid arthritis, systemic lupus erythematosus, hepatitis, dysmenorrhea, muscle cramping and spasms, and fever for more than 1200 years. A water/ethanol extract of the root is now known as total glucosides of peony (TGP), which contains more than 15 components. Paeoniflorin is the most abundant ingredient and accounts for the pharmacological effects observed with TGP in both in vitro and in vivo studies. The analgesic effect of TGP was confirmed in various animal models of pain, which may be mediated partly by adenosine A1 receptor. The direct anti-inflammatory effects of TGP were observed in animal models of both acute and subacute inflammation, by inhibiting the production of prostaglandin E2, leukotriene B4, and nitric oxide, and by suppressing the increase of intracellular calcium ion concentration. TGP was also reported to have protective effects of cells against oxidative stress. In vitro, dual effects of TGP were noted on the proliferation of lymphocytes, differentiation of Th/Ts lymphocytes, and the production of proinflammatory cytokines and antibodies. In vivo, TGP inhibited the delayed-type hypersensitivity in immuno-activated mice, and enhanced the delayed-type hypersensitivity in immuno-suppressed mice. In adjuvant arthritis rats, paeoniflorin exerted immunosuppressive effects. The beneficial effects of TGP in treating rheumatoid arthritis were verified by randomized controlled trials. The adverse events of TGP were mainly gastrointestinal tract disturbances, mostly mild diarrhea.

Front Pharmacol. 2011 Feb 25;2:10

The Beneficial Effect of Total Glucosides of Paeony on Psoriatic Arthritis Links to Circulating Tregs and Th1 Cell Function.

Total glycosides of peony (TGP) is a natural immuno-modulatory drug extracted from traditional Chinese herb peony. It has been approved by State Food and Drug Administration for the treatment of rheumatoid arthritis. However, data of TGP effect on psoriatic arthritis (PsA) is still scarce. In this study, 19 patients with PsA received 12-week treatment of TGP, and clinical efficacy in joint manifestations was evaluated by DAS28 at weeks 0, 4, 8 and 12. Peripheral percentages of Tregs, Th1, Th2 and NK cells were analyzed, and serum Th1-type cytokines (IL-12, IFN-g and TNF-a), Th2-type cytokines (IL-4, IL-5 and IL-10) as well as pro-inflammatory factors (IL-2, IL-6 and IL-8) were concomitantly examined. Six patients (32%) exhibited ≥25% decrease of DAS28 (responders). Interestingly, all responders displayed a continuous decrease in Treg and Th1 numbers during TGP treatment, concomitant with significant decreases in Th1-type cytokine levels. Serum IL-6 also showed a significant decline in responders. Non-responders lacked these sequential alterations. Thus, TGP merits further consideration as a promising therapeutic option for PsA. The result indicated that recovery of Tregs and Th1 may serve as prognostic markers to assess responsiveness to TGP treatment in PsA.

Phytother Res. 2013 Apr 23

Renoprotective effect of total glucosides of paeony (TGP) and its mechanism in experimental diabetes.

Total glucosides of paeony (TGP), extracted from the root of Paeonia lactiflora pall, has been shown to have ant-inflammatory and antioxidative actions. The aims of this study were to elucidate the renoprotective effect of TGP and its mechanism in experimental diabetes. Streptozotocin-induced diabetic rats were treated with TGP for 8 weeks. Treatment with TGP at 50, 100, and 200 mg/kg significantly lowered 24-h urinary albumin excretion rate in diabetic rats. TGP treatment in all doses markedly attenuated glomerular volume, and treatment with TGP at 100 and 200 mg/kg markedly reduced indices for tubulointerstitial injury in diabetic rats. Western blot analysis showed that the expressions of 1 alpha (IV) collagen, intercellular adhesion molecule (ICAM)-1, interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, NF-kappaB p65, and 3-nitrotyrosine (3-NT) protein were increased in the kidneys of diabetic rats; the increases in these proteins were all dose-dependently and significantly inhibited by TGP treatment. The expression of nephrin protein was significantly reduced in the kidneys from diabetic rats and markedly increased by TGP treatment. The expression of transforming growth factor (TGF)-beta1 protein in the kidney was also significantly increased in diabetic rats, which was significantly inhibited by treatment with TGP at all doses. Our data suggest that TGP treatment ameliorates early renal injury via the inhibition of expression of ICAM-1, IL-1, TNF-alpha, and 3-NT in the kidneys of diabetic rats.

J Pharmacol Sci. 2009 Jan;109(1):78-87

The anti-inflammatory effect of paeoniflorin on cerebral infarction induced by ischemia-reperfusion injury in Sprague-Dawley rats.

Paeoniflorin, a component in Paeonia lactiflora Pall, inhibits nuclear factor-kappaB expression in chronic hypoperfusion rat and has anti-inflammatory properties. Therefore, the aim of the present study was to investigate the effect of paeoniflorin on cerebral infarct, and the involvement of anti-inflammation. We established an animal model of cerebral infarct by occluding both the common carotid arteries and the right middle cerebral artery for 90 min, followed by reperfusion of 24 hours. The ratios of cerebral infarction area to total brain area, and neuro-deficit score were used as an index to observe the effects of paeoniflorin on cerebral infarct. ED1 (mouse anti rat CD68), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), intercellular adhesion molecular-1 (ICAM-1), myeloperoxidase (MPO) immunostaining and apoptotic cells in the cerebral infarction region also were studied. The results indicated that both pre-treatment and post-treatment with paeoniflorin reduced the ratio of cerebral infarction area; pre-treatment with paeoniflorin also reduced the neurological deficit score. The counts of ED1, IL-1beta, TNF-alpha, ICAM-1 of microvessels and MPO immunoreactive cells and apoptotic cells were increased in the cerebral infarction region; however, these increases were reduced by Paeoniflorin pre-treatment. In conclusion, Paeoniflorin reduced cerebral infarct and neurological deficit in ischemia-reperfusion injured rats, suggesting that paeoniflorin may have a similar effect in humans and might be a suitable treatment for stroke. Paeoniflorin reduced cerebral infarct, at least in part, involves the anti-inflammatory properties.

Am J Chin Med. 2010;38(1):51-64

Paeoniflorin inhibits function of synoviocytes pretreated by rIL-1a and regulates EP4 receptor expression.

ETHNOPHARMACOLOGICAL RELEVANCE: To investigate the effect of the Paeoniflorin (Pae), a main active component of total glucosides of paeony (TGP) extracted from the root of Paeonia lactiflora, on regulation of synoviocytes cultured from rats collagen-induced arthritis (CIA) in vitro. MATERIALS AND METHODS: CIA was induced in male Sprague-Dawley rats immunized with chicken type II collagen (CCII) in Freund’s complete adjuvant. The levels of interleukin-1 (IL-1), tumor necrosis factor a (TNF-a), prostaglandin E(2) (PGE(2)) and cyclic adenosine monophosphate (cAMP) were measured by radioimmunoassay. The proliferation responses was determined by the 3-(4,5-2dimethylthiazal-2yl) 2,5-diphenyltetrazoliumbromide (MTT) assay. Expression of E-prostanoid (EP(4)) receptor was detected by Western blotting technique. RESULTS: Treatment of Pae (2.5, 12.5, 62.5 µg/ml) significantly decreased the production of IL-1 and TNF-a. Recombinant interleukin-1 (rIL-1a) (10 ng/ml) apparently stimulated synoviocyte, thymocyte and splenocyte proliferation, and Pae (12.5, 62.5 µg/ml) inhibited abnormal proliferation responses stimulated by rIL-1a. Moreover, rIL-1a time- and concentration-dependently increased production of PGE(2). The production of PGE(2) produced by synoviocytes from CIA rats significantly inhibited by administration of Pae (12.5, 62.5 µg/ml). rIL-1a (10 ng/ml) decreased cAMP of synoviocytes cells treated for 24h. Similarly rIL-1a (0.1, 1, 10 ng/ml) induced a concentration-dependent decrease in the production of cAMP at 24h. Pae (12.5, 62.5 µg/ml) increased the production of cAMP in synoviocytes. The immunoblot, Pae (12.5, 62.5 µg/ml) apparently increased the expression of EP(4) receptor in synoviocytes stimulated by rIL-1α (10 ng/ml). CONCLUSIONS: The present study indicates that Pae might exert its anti-inflammatory effects through suppressing synoviocytes function and regulating immune cells responses in CIA rats, which might be associated with its ability to up-regulate the E-prostanoid (EP(4)) receptor protein expression and modulate intracellular cAMP level.

J Ethnopharmacol. 2011 Oct 11;137(3):1275-82

Paeoniflorin inhibits proliferation of fibroblast-like synoviocytes through suppressing G-protein-coupled receptor kinase 2.

Paeoniflorin (Pae) is a monoterpene glucoside and the main component of the total glucosides of paeony (TGP) extracted from the roots of Paeonia lactiflora. Its anti-inflammatory effect is associated with regulating G-protein-coupled receptors (GPCRs) signaling. The aim of this study was to explore the expression change of G-protein-coupled receptor kinase 2 (GRK2) in fibroblast-like synoviocytes (FLS) and the effect of Pae. Pae was obtained and purified from the roots of Paeonia lactiflora. We investigated the expression of GRK2 in synovium during the inflammatory process and assessed the effects of a specific GRK2 inhibitor and Pae on proliferation, cAMP level, and protein kinase A (PKA) activity of FLS in vitro. Additionally, the effect of Pae on GRK2 expression in FLS was detected in vitro. Expression of GRK2 in synovium from CIA rats increased during the inflammatory process. The specific GRK2 inhibitor suppressed proliferation and increased the cAMP level as well as PKA activity of FLS, and Pae had the same effects. Furthermore, Pae decreased GRK2 expression in FLS in vitro. Our results indicate that a chronic inflammatory process in CIA induces upregulation of GRK2 expression in FLS, and Pae can reverse this change, which might be one of the important mechanisms for Pae regulating GPCRs signaling and suppressing the proliferation of FLS in CIA.

Planta Med. 2012 May;78(7):665-71

Effect and mechanism of action of total glucosides of paeony on synoviocytes from rats with collagen-induced arthritis.

AIM: To study the effect and mechanism of action of total glucosides of paeony (TGP) on synoviocytes from rats with collagen-induced arthritis (CIA). METHODS: Chicken type II collagen was used to induce CIA in rats. Synoviocytes were separated by incubation with collagenase and trypsin, and its ultrastructural changes were observed under transmission electron microscope. Synoviocyte proliferation was determined by 3-(4,5-dimethylthiazal-2yl) 2,5- diphenyltetrazoliumbromide (MTT) assay, and IL-1 activity in synoviocytes supernatant was measured by thymocyte proliferation assay. TNFa and PGE, produced by synoviocytes were determined by radioimmunoassay. RESULTS: TGP was shown to protect CIA rats against the ultrastructural damages of synoviocytes. Meanwhile, TGP also suppressed the excessive synoviocyte proliferation and over-production of IL-1, TNFalpha and PGE2. CONCLUSION: TGP has inhibitory effect on hyperfunctional synoviocytes of CIA rats and its mechanism of action may be related with the inhibition of abnormal proliferation and secretion of synoviocytes.

Yao Xue Xue Bao. 2006 Feb;41(2):166-70

Total glucosides of paeony inhibits Th1/Th17 cells via decreasing dendritic cells activation in rheumatoid arthritis.

Total glucoside of paeony (TGP), an active compound extracted from paeony root, has been used in therapy for rheumatoid arthritis (RA). Th1 and Th17 cells are now believed to play crucial roles in the lesions of RA. However, the molecular mechanism of TGP in inhibition of Th1 and Th17 cells remains unclear. In this study, we found that TGP treatment significantly decreased percentage and number of Th1 and Th17 cells in collagen induced arthritis (CIA) mice. Consistently, treatment with TGP decreased expression of T-bet and RORgt as well as phosphorylation of STAT1 and STAT3. In particular, TGP treatment inhibited dendritic cells (DCs) maturation and reduced production of IL-12 and IL-6. Moreover, TGP-treatment RA patients showed shank population of matured DCs and IFN-g-, IL-17-producing cells. Taken together, our results demonstrated that TGP inhibited maturation and activation of DCs, which led to impaired Th1 and Th17 differentiation in vivo.

Cell Immunol. 2012 Dec;280(2):156-63

Therapeutic effect of total glucosides of paeony on lupus nephritis in MRL/lpr mice.

OBJECTIVE: To observe the therapeutic effect of total glucosides of paeony (TGP) on lupus nephritis (LN) in MRL/lpr mice. METHODS: MRL/lpr mice with lupus nephritis were randomized into model group and TGP group. The urinary protein content was detected using Coomassie brilliant blue, and the serum levels of IgG anti-double-stranded DNA (dsDNA) antibodies and antinuclear antibodies (ANA) were measured by enzyme-linked immunosorbent assay (ELISA). The changes in the renal pathology were examined microscopically, and the spleen and thymus were weighed to calculate the spleen and thymus indexes. RESULTS: At 15 and 30 days after TGP administration, the urinary protein content in the TGP group was significantly lower than that in the model group (P<0.05). TGP treatment significantly lowered the serum levels of anti-dsDNA antibodies and ANA and the weight and index of spleen (P<0.05), resulting also in lessened renal pathology at 30 days after the administration. Compared to those before TGP treatment, the urinary protein content and the levels of anti-dsDNA antibodies and ANA decreased significantly at 15 and 30 days after TGP administration (P<0.05), while in the model group, the level of anti-dsDNA increased significantly without obvious changes in urinary protein content or ANA. At 30 days after TGP administration, the urinary protein content was significantly lowered in the TGP group as compared to that at 15 days (P<0.05), but the antibodies showed no significant changes. CONCLUSION: TGP can reduce urinary protein content and serum levels of anti-dsDNA antibodies and ANA, and lessen renal pathology in MRL/lpr mice with lupus nephritis, suggesting its therapeutic effect on lupus nephritis.

Nan Fang Yi Ke Da Xue Xue Bao. 2011 Apr;31(4):656-60

Clinical observation on the treatment of chronic urticaria with total glucosides of paeony capsule combined with citirizine.

OBJECTIVE: To assess the effect and adverse reaction of total glucosides of paeony capsule (TGPC) in combining with citirizine for the treatment of chronic urticaria. METHODS: A total of 120 patients were assigned to two groups by lottery, 65 in the treated group and 55 in the control group. They all were orally treated with citirizine tablet 10 mg per day, but to the treated group, additional 0.2 g TGPC was given three times per day, the therapeutic course for both groups was 4 weeks. The effectiveness of treatment was observed, and the changes of total symptom score, serum levels of interleukin-4 (IL-4), and immunoglobulin E (IgE) were measured before and after treatment. Moreover, a follow-up was carried out one month after ending the treatment.

RESULTS: The dropped cases were two in the treated group and seven in the control group; so, the study was accomplished on 63 patients in the treated group and 48 patients in the control group. The total effective rate was assessed at 73.02% (46/63) in the treated group, which was significantly higher than 47.92% (23/48) in the control group (P<0.01). After treatment, the total symptom score decreased in both groups, but the decrement in the treated group was more significant (P<0.05). Serum levels of IL-4 and IgE in the treated group lowered significantly, while the changes in the control group were insignificant, so statistical significant differences were shown between groups (P<0.01). A follow-up study showed that the relapse rate in the treated group was 30.00% (6/20), while that in the control group was 90.00% (9/10), and the former was lower than the latter (P<0.01). Adverse reactions, revealed as drowsiness, dizziness, and weakness, were seen in eight cases and seven cases in the two groups, respectively. Besides, mild diarrhea occurred in two cases of the treated group. CONCLUSIONS: The treatment of TGPC combining citirizine shows definite curative effect in treating chronic urticaria, with low relapse rate and without evident adverse reaction. Its therapeutic effect might be realized by means of regulating patients’ immune function. Besides, the medication should be continued for a rather long period to achieve the full effect.

Chin J Integr Med. 2010 Aug;16(4):353-6

High serum testosterone is associated with reduced risk of cardiovascular events in elderly men. The MrOS (Osteoporotic Fractures in Men) study in Sweden.

OBJECTIVES: We tested the hypothesis that serum total testosterone and sex hormone-binding globulin (SHBG) levels predict cardiovascular (CV) events in community-dwelling elderly men. BACKGROUND: Low serum testosterone is associated with increased adiposity, an adverse metabolic risk profile, and atherosclerosis. However, few prospective studies have demonstrated a protective link between endogenous testosterone and CV events. Polymorphisms in the SHBG gene are associated with risk of type 2 diabetes, but few studies have addressed SHBG as a predictor of CV events. METHODS: We used gas chromatography/mass spectrometry to analyze baseline levels of testosterone in the prospective population-based MrOS (Osteoporotic Fractures in Men) Sweden study (2,416 men, age 69 to 81 years). SHBG was measured by immunoradiometric assay. CV clinical outcomes were obtained from central Swedish registers. RESULTS: During a median 5-year follow-up, 485 CV events occurred. Both total testosterone and SHBG levels were inversely associated with the risk of CV events (trend over quartiles: p = 0.009 and p = 0.012, respectively). Men in the highest quartile of testosterone (≥550 ng/dl) had a lower risk of CV events compared with men in the 3 lower quartiles (hazard ratio: 0.70, 95% confidence interval: 0.56 to 0.88). This association remained after adjustment for traditional CV risk factors and was not materially changed in analyses excluding men with known CV disease at baseline (hazard ratio: 0.71, 95% confidence interval: 0.53 to 0.95). In models that included both testosterone and SHBG, testosterone but not SHBG predicted CV risk. CONCLUSIONS: High serum testosterone predicted a reduced 5-year risk of CV events in elderly men.

J Am Coll Cardiol. 2011 Oct 11;58(16):1674-81

Association of testosterone therapy with mortality, myocardial infarction, and stroke in men with low testosterone levels.

IMPORTANCE: Rates of testosterone therapy are increasing and the effects of testosterone therapy on cardiovascular outcomes and mortality are unknown. A recent randomized clinical trial of testosterone therapy in men with a high prevalence of cardiovascular diseases was stopped prematurely due to adverse cardiovascular events raising concerns about testosterone therapy safety. OBJECTIVES: To assess the association between testosterone therapy and all-cause mortality, myocardial infarction (MI), or stroke among male veterans and to determine whether this association is modified by underlying coronary artery disease. DESIGN, SETTING, AND PATIENTS: A retrospective national cohort study of men with low testosterone levels (<300 ng/dL) who underwent coronary angiography in the Veterans Affairs (VA) system between 2005 and 2011. MAIN OUTCOMES AND MEASURES: Primary outcome was a composite of all-cause mortality, MI, and ischemic stroke. RESULTS: Of the 8,709 men with a total testosterone level lower than 300 ng/dL, 1,223 patients started testosterone therapy after a median of 531 days following coronary angiography. Of the 1,710 outcome events, 748 men died, 443 had MIs, and 519 had strokes. Of 7,486 patients not receiving testosterone therapy, 681 died, 420 had MIs, and 486 had strokes. Among 1223 patients receiving testosterone therapy, 67 died, 23 had MIs, and 33 had strokes. The absolute rate of events were 19.9% in the no testosterone therapy group vs 25.7% in the testosterone therapy group, with an absolute risk difference of 5.8% (95% CI, -1.4% to 13.1%) at 3 years after coronary angiography. In Cox proportional hazards models adjusting for the presence of coronary artery disease, testosterone therapy use as a time-varying covariate was associated with increased risk of adverse outcomes (hazard ratio, 1.29; 95% CI, 1.04 to 1.58). There was no significant difference in the effect size of testosterone therapy among those with and without coronary artery disease (test for interaction, P = .41). CONCLUSIONS AND RELEVANCE: Among a cohort of men in the VA health care system who underwent coronary angiography and had a low serum testosterone level, the use of testosterone therapy was associated with increased risk of adverse outcomes. These findings may inform the discussion about the potential risks of testosterone therapy.

JAMA. 2013 Nov 6;310(17):1829-36

The Relationship between Testosterone Deficiency and Men’s Health.

Testosterone is important in the physiology of various organs and tissues. The serum testosterone concentration gradually declines as one of the processes of aging. Thus, the concept of late-onset hypogonadism has gained increasing attention in the last few years. Reported symptoms of late-onset hypogonadism are easily recognized and include diminished sexual desire and erectile quality, particularly in nocturnal erections, changes in mood with concomitant decreases in intellectual activity and spatial orientation, fatigue, depression and anger, a decrease in lean body mass with associated decreases in muscle volume and strength, a decrease in body hair and skin alterations, and decreased bone mineral density resulting in osteoporosis. Among these various symptoms, sexual dysfunction has been the most common and necessary to treat in the field of urology. It is well known that a low serum testosterone level is associated with erectile dysfunction and hypoactive sexual libido and that testosterone replacement treatment can improve these symptoms in patients with hypogonadism. Recently, in addition to sexual dysfunction, a close relationship between metabolic syndrome, characterized by central obesity, insulin resistance, dyslipidemia, and hypertension, and late-onset hypogonadism has been highlighted by several epidemiologic studies. Several randomized control trials have shown that testosterone replacement treatment significantly decreases insulin resistance in addition to its advantage for obesity. Furthermore, metabolic syndrome is one of the major risk factors for cardiovascular disease, and a low serum testosterone level is closely related to the development of atherosclerosis. Presently, it is speculated that a low serum testosterone level may increase the risk for cardiovascular disease. Thus, testosterone is a key molecule in men’s health, especially that of elderly men.

World J Mens Health. 2013 Aug;31(2):126-35.

Clinical use of androgens.

The principal clinical use of androgens is the treatment of testosterone deficiency in a male who has primary hypogonadism or who has secondary hypogonadism but is not interested in becoming fertile within the subsequent year. For the treatment of testosterone deficiency in the adult male, one of the two long-acting esters of testosterone, testosterone enanthate or testosterone cypionate, should be administered by intramuscular injection, 200 mg every two weeks or 300 mg every three weeks. The alkylated testosterone derivatives, which can be administered orally, are probably too weak as androgens to be used for the treatment of adult male hypogonadism, but they may have value in situations where full androgenization is not desired, such as adjuvant treatment of breast carcinoma.

Annu Rev Med. 1984;35:207-17

Emerging drugs for hypogonadism.

Male hypogonadism is a common endocrine problem that affects men of all ages. Recently, there has been a surge in testosterone use among middle-aged and older men who in the past may have been considered to have borderline or even normal testosterone levels. This increasing use of testosterone therapy among men has paralleled the increasing improvements in the development of treatments for male hypogonadism that have been made over the past few decades. Current therapies using transdermal formulations and long-acting injectables such as testosterone undecanoate are quickly replacing the old injectable testosterone esters. In recent years, pharmaceutical sales and prescription data have readily shown a shift in the testosterone marketplace towards greater use of slightly more expensive treatments such as transdermal therapies, which are easier to administer and yield more physiological levels of testosterone. On the horizon are several new compounds in development, such as selective androgen receptor modulators (SARMS), 7alpha-methyl-19-nortestosterone, aromatase inhibitors, clomifene, dihydrotestosterone and human chorionic gonadotropin. Compounds such as SARMs are designed to selectively target androgen receptors in specific tissues (such as bone and muscles), in the hope of dispersing some of the side effects experienced on the prostate, which are presently associated with therapy of exogenous testosterone.

Expert Opin Emerg Drugs. 2006 Nov;11(4):685-707

Circulating estradiol and mortality in men with systolic chronic heart failure.

CONTEXT: Androgen deficiency is common in men with chronic heart failure (HF) and is associated with increased morbidity and mortality. Estrogens are formed by the aromatization of androgens; therefore, abnormal estrogen metabolism would be anticipated in HF. OBJECTIVE: To examine the relationship between serum concentration of estradiol and mortality in men with chronic HF and reduced left ventricular ejection fraction (LVEF). DESIGN, SETTING, AND PARTICIPANTS: A prospective observational study at 2 tertiary cardiology centers (Wroclaw and Zabrze, Poland) of 501 men (mean [SD] age, 58 [12] years) with chronic HF, LVEF of 28% (SD, 8%), and New York Heart Association [NYHA] classes 1, 2, 3, and 4 of 52, 231, 181, and 37, respectively, who were recruited between January 1, 2002, and May 31, 2006. Cohort was divided into quintiles of serum estradiol (quintile 1, < 12.90 pg/mL; quintile 2, 12.90-21.79 pg/mL; quintile 3, 21.80-30.11 pg/mL; quintile 4, 30.12-37.39 pg/mL; and quintile 5, > or = 37.40 pg/mL). Quintile 3 was considered prospectively as the reference group. MAIN OUTCOME MEASURES: Serum concentrations of estradiol and androgens (total testosterone and dehydroepiandrosterone sulfate [DHEA-S]) were measured using immunoassays. RESULTS: Among 501 men with chronic HF, 171 deaths (34%) occurred during the 3-year follow-up. Compared with quintile 3, men in the lowest and highest estradiol quintiles had increased mortality (adjusted hazard ratio [HR], 4.17; 95% confidence interval [CI], 2.33-7.45 and HR, 2.33; 95% CI, 1.30-4.18; respectively; P < .001). These 2 quintiles had different clinical characteristics (quintile 1: increased serum total testosterone, decreased serum DHEA-S, advanced NYHA class, impaired renal function, and decreased total fat tissue mass; and quintile 5: increased serum bilirubin and liver enzymes, and decreased serum sodium; all P < .05 vs quintile 3). For increasing estradiol quintiles, 3-year survival rates adjusted for clinical variables and androgens were 44.6% (95% CI, 24.4%-63.0%), 65.8% (95% CI, 47.3%-79.2%), 82.4% (95% CI, 69.4%-90.2%), 79.0% (95% CI, 65.5%-87.6%), and 63.6% (95% CI, 46.6%-76.5%); respectively (P < .001). CONCLUSION: Among men with chronic HF and reduced LVEF, high and low concentrations of estradiol compared with the middle quintile of estradiol are related to an increased mortality.

JAMA. 2009 May 13;301(18):1892-901

Age trends in estradiol and estrone levels measured using liquid chromatography tandem mass spectrometry in community-dwelling men of the Framingham Heart Study.

BACKGROUND: Age trends in estradiol and estrone levels in men and how lifestyle factors, comorbid conditions, testosterone, and sex hormone-binding globulin affect these age trends remain poorly understood, and were examined in men of the Framingham Heart Study. METHODS: Estrone and estradiol concentrations were measured in morning fasting samples using liquid chromatography tandem mass spectrometry in men of Framingham Offspring Generation. Free estradiol was calculated using a law of mass action equation. RESULTS: There were 1,461 eligible men (mean age [±SD] 61.1±9.5 years and body mass index [BMI] 28.8±4.5kg/m(2)). Total estradiol and estrone were positively associated with age, but free estradiol was negatively associated with age. Age-related increase in total estrone was greater than that in total estradiol. Estrone was positively associated with smoking, BMI, and testosterone, and total and free estradiol with diabetes, BMI, testosterone, and comorbid conditions; additionally, free estradiol was associated negatively with smoking. Collectively, age, BMI, testosterone, and other health and behavioral factors explained only 18% of variance in estradiol, and 9% of variance in estrone levels. Men in the highest quintile of estrone levels had significantly higher age and BMI, and a higher prevalence of smoking, diabetes, and cardiovascular disease than others, whereas those in the highest quintile of estradiol had higher BMI than others. CONCLUSIONS: Total estrone and estradiol levels in men, measured using liquid chromatography tandem mass spectrometry, revealed significant age-related increases that were only partially accounted for by cross-sectional differences in BMI, diabetes status, and other comorbidities and health behaviors. Longitudinal studies are needed to confirm these findings.

J Gerontol A Biol Sci Med Sci. 2013 Jun;68(6):733-40

Long-term benefits of testosterone replacement therapy on angina threshold and atheroma in men.

INTRODUCTION: In short-term studies, testosterone replacement therapy has been shown to protect male subjects from exercise-induced ischaemia and modify cardiovascular risk factors such as insulin resistance, fat mass and lipid profiles. METHODS: This randomised parallel group controlled trial was designed to assess the treatment effect of testosterone therapy (Nebido) compared with placebo in terms of exercise-induced ischaemia, lipid profiles, carotid intima-media thickness (CIMT) and body composition during 12 months treatment in men with low testosterone levels and angina. RESULTS: A total of 15 men were recruited but 13 (n=13) reached adequate duration of follow-up; seven were treated with testosterone and six with placebo. Testosterone increased time to ischaemia (129+/-48 s versus 12+/-18, P=0.02) and haemoglobin (0.4+/-0.6 g/dl versus -0.03+/-0.5, P=0.04), and reduced body mass index (-0.3 kg/m(2) versus 1.3+/-1, P=0.04) and triglycerides (-0.36+/-0.4 mmol/l versus 0.3+/-1.2, P=0.05). The CIMT decreased in the testosterone group more than placebo, but full between group analyses suggested this was only a statistical trend (-0.5+/-0.1 vs -0.09+/-0.06, P=0.16). There were no significant effects on serum prostate specific antigen, total or high-density lipoprotein cholesterol; or on mood and symptom scores as assessed by Seattle Angina Score and EuroQol. CONCLUSION: The protective effect of testosterone on myocardial ischaemia is maintained throughout treatment without decrement. Previously noted potentially beneficial effects of testosterone on body composition were confirmed and there were no adverse effects.

Eur J Endocrinol. 2009 Sep;161(3):443-9

Low plasma testosterone and elevated carotid intima-media thickness: importance of low-grade inflammation in elderly men.

CONTEXT AND OBJECTIVE: An inverse correlation between plasma testosterone levels and carotid intima-media thickness (IMT) has been reported in men. We investigated whether this association could be mediated or modified by traditional cardiovascular risk factors as well as inflammatory status. METHODS: In the Three-City population-based cohort study, 354 men aged 65 and over had available baseline data on hormones levels and carotid ultrasonography. Plasma concentrations of testosterone (total and bioavailable), estradiol and sex hormone-binding globulin (SHBG), together with cardiovascular risk factors were measured. IMT in plaque-free site and atherosclerotic plaques in the extracranial carotid arteries were determined using a standardized protocol. Multiple linear regression models were used to analyze this association and interaction study.RESULTS: Analyses with and without adjustment for cardiovascular risk factors showed that carotid IMT was inversely and significantly correlated with total and bioavailable testosterone levels but not with SHBG and estradiol levels. This association depended on C-reactive protein (CRP) levels (p for interaction <0.05). Among men with low-grade inflammation (CRP ≥2 mg/L), mean IMT was higher in subjects with bioavailable testosterone ≤ 3.2 ng/mL than in those with bioavailable testosterone > 3.2 ng/mL (0.76 mm and 0.70 mm respectively, p < 0.01). By contrast, among men with CRP ≤ 2 mg/L, mean IMT was similar in both groups (0.72 mm and 0.71 mm respectively, p = 0.77). Similar results were found for total testosterone although not significant. No association was found between plasma hormones levels and atherosclerotic plaques. CONCLUSION: In elderly men, low plasma testosterone is associated with elevated carotid intima-media thickness only in those with low-grade inflammation. Traditional risk factors have no mediator role.

Atherosclerosis. 2012 Jul;223(1):244-9

Testosterone supplementation in heart failure: a meta-analysis.

BACKGROUND: Low testosterone is an independent predictor of reduced exercise capacity and poor clinical outcomes in patients with heart failure (HF). We sought to determine whether testosterone therapy improves exercise capacity in patients with stable chronic HF. METHODS AND RESULTS: We searched Medline, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (1980-2010). Eligible studies included randomized controlled trials (RCTs) reporting the effects of testosterone on exercise capacity in patients with HF. Reviewers determined the methodological quality of studies and collected descriptive, quality, and outcome data. Four trials (n=198; men, 84%; mean age, 67 years) were identified that reported the 6-minute walk test (2 RCTs), incremental shuttle walk test (2 RCTs), or peak oxygen consumption (2 RCTs) to assess exercise capacity after up to 52 weeks of treatment. Testosterone therapy was associated with a significant improvement in exercise capacity compared with placebo. The mean increase in the 6-minute walk test, incremental shuttle walk test, and peak oxygen consumption between the testosterone and placebo groups was 54.0 m (95% CI, 43.0-65.0 m), 46.7 m (95% CI, 12.6-80.9 m), and 2.70 mL/kg per min (95% CI, 2.68-2.72 mL/kg per min), respectively. Testosterone therapy was associated with a significant increase in exercise capacity as measured by units of pooled SDs (net effect, 0.52 SD; 95% CI, 0.10-0.94 SD). No significant adverse cardiovascular events were noted. CONCLUSIONS: Given the unmet clinical needs, testosterone appears to be a promising therapy to improve functional capacity in patients with HF. Adequately powered RCTs are required to assess the benefits of testosterone in this high-risk population with regard to quality of life, clinical events, and safety.

Circ Heart Fail. 2012 May 1;5(3):315-21

Zinc-altered immune function.

Zinc is known to be essential for all highly proliferating cells in the human body, especially the immune system. A variety of in vivo and in vitro effects of zinc on immune cells mainly depend on the zinc concentration. All kinds of immune cells show decreased function after zinc depletion. In monocytes, all functions are impaired, whereas in natural killer cells, cytotoxicity is decreased, and in neutrophil granulocytes, phagocytosis is reduced. The normal functions of T cells are impaired, but autoreactivity and alloreactivity are increased. B cells undergo apoptosis. Impaired immune functions due to zinc deficiency are shown to be reversed by an adequate zinc supplementation, which must be adapted to the actual requirements of the patient. High dosages of zinc evoke negative effects on immune cells and show alterations that are similar to those observed with zinc deficiency. Furthermore, when peripheral blood mononuclear cells are incubated with zinc in vitro, the release of cytokines such as interleukins (IL)-1 and -6, tumor necrosis factor-alpha, soluble IL-2R and interferon-gamma is induced. In a concentration of 100 micro mol/L, zinc suppresses natural killer cell killing and T-cell functions whereas monocytes are activated directly, and in a concentration of 500 micro mol/L, zinc evokes a direct chemotactic activation of neutrophil granulocytes. All of these effects are discussed in this short overview.

J Nutr. 2003 May;133(5 Suppl 1):1452S-6S

Zinc in cancer prevention.

Essentiality of zinc for humans was discovered 45 yr ago. Deficiency of zinc is prevalent world wide in developing countries and may affect nearly 2 billion subjects. The major manifestations of zinc deficiency include growth retardation, hypogonadism in males, cell-mediated immune dysfunctions, and cognitive impairment. Zinc not only improves cell mediated immune functions but also functions as an antioxidant and anti-inflammatory agent. Oxidative stress and chronic inflammation have been implicated in development of many cancers. In patients with head and neck cancer, we have shown that nearly 65% of these patients were zinc deficient based on their cellular zinc concentrations. Natural killer (NK) cell activity and IL-2 generation were also affected adversely. Th2 cytokines were not affected. In our patients, zinc status was a better indicator of tumor burden and stage of disease in comparison to the overall nutritional status. Zinc status also correlated with number of hospital admissions and incidences of infections. NF-kappa B is constitutively activated in many cancer cells, and this results in activation of antiapoptotic genes, VEGF, cyclin DI, EGFR, MMP-9 and inflammatory cytokines. Zinc inhibits NF-kappa B via induction of A-20. Thus, zinc supplementation should have beneficial effects on cancer by decreasing angiogenesis and induction of inflammatory cytokines while increasing apoptosis in cancer cells. Based on the above, we recommend further studies and propose that zinc should be utilized in the management and chemoprevention of cancer.

Nutr Cancer. 2009;61(6):879-87

In vitro ¹⁴C-labeled amino acid uptake changes and surface abnormalities in the colon after 1,2-dimethylhydrazine-induced experimental carcinogenesis: protection by zinc.

The present study explored the regulatory role of zinc on the in vitro uptake of ¹⁴C-glucose and ¹⁴C-labeled amino acids and on colonic surface abnormalities after 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. Rats were segregated into four groups: control, DMH-treated, zinc-treated, and DMH + zinc-treated. Colon carcinogenesis was induced through weekly subcutaneous injections of DMH (30 mg/kg body weight) for 16 weeks. Zinc (in the form of zinc sulfate) was given to rats at a dose level of 227 mg/L in their drinking water. DMH treatment caused a significant decrease in the activities of disaccharidases (sucrase, lactase, and maltase), but a significant increase in the activity of alkaline phosphatase. In vitro uptake of ¹⁴C-D-glucose and the amino acids ¹⁴C-glycine, ¹⁴C-alanine, ¹⁴C-lysine, and ¹⁴C-leucine were significantly higher in the colons of DMH-treated rats. Zinc supplementation of DMH-treated rats resulted in regulating the altered intestinal enzyme activities and in vitro uptake of ¹⁴C-amino acids and ¹⁴C-glucose. Scanning electron microscopy revealed drastic alterations in the colon surface morphology after DMH treatment, which were restored after zinc supplementation. Our results confirm a beneficial effect of zinc against DMH-induced alterations in the colons of rats.

J Environ Pathol Toxicol Oncol. 2011;30(2):103-11

Zinc supplementation suppresses 4-nitroquinoline 1-oxide-induced rat oral carcinogenesis.

Dietary zinc (Zn) deficiency is implicated in the pathogenesis of human oral-esophageal cancers. In rats, Zn deficiency causes increased cell proliferation and cyclooxygenase-2 (COX-2) overexpression and enhances oral carcinogenesis by 4-nitroquinoline 1-oxide (NQO). Zn replenishment reverses all these effects. We questioned whether Zn has antitumor efficacy in a Zn-sufficient animal by investigating in Zn-sufficient rats (i) the efficacy of Zn supplementation on the progression of tongue squamous cell carcinogenesis induced by drinking water exposure to high (20-30 p.p.m.) and low (10 p.p.m.) doses of NQO and (ii) the modulating effects of Zn supplementation on biomarker expression in tongue lesions by immunohistochemistry. In rats exposed to high doses of NQO, Zn supplementation significantly reduced the incidence of papillomas from 100 to 64.7% (P=0.018) and invasive carcinomas from 93.8 to 52.9% (P=0.017). In rats exposed to low doses of NQO, where only minimally invasive carcinomas developed, Zn supplementation significantly reduced tumor multiplicity, incidence of tumors (1-2 mm), hyperplasia, dysplasia, papillomas and progression to carcinoma. Immunohistochemical analysis of carcinomas showed that Zn supplementation caused a shift to a less proliferative/aggressive cancer phenotype by reducing cell proliferation, stimulating apoptosis and decreasing expression of the key tumor markers cyclin D1, p53 and COX-2. Additionally, Zn supplementation significantly reduced cell proliferation in non-lesional tongue squamous epithelia, thereby suppressing tumor development. Together, the results demonstrate that Zn supplementation has chemopreventive efficacy against oral carcinogenesis in nutritionally complete animals. Our data suggest that Zn supplementation may be efficacious in the chemoprevention of human oral cancer.

Carcinogenesis. 2011 Apr;32(4):554-60

Effects of zinc supplementation on the anthropometric measurements, lipid profiles and fasting blood glucose in the healthy obese adults.

Purpose : The aim of this study was to assess the effects of zinc supplementation on anthropometric measures, improving lipid profile biomarkers, and fasting blood glucose level in obese people. Methods: This randomized, double- blind clinical trial was carried out on 60 obese participants in the 18-45 age range for one month. The participants were randomly divided into the intervention group, who received 30 mg/d zinc gluconate, and the placebo group who received 30mg/d starch. Anthropometric measurements (body mass index (BMI), weight and waist circumference) were recorded before and at the end of study. Lipid profile biomarkers and fasting blood glucose were determined using enzymatic procedure. Analysis of Covariance (ANCOVA) test was run to compare the post-treatment values of the two groups, and t-test was conducted to compare within group changes. Results: Serum zinc concentration was increased significantly in intervention group (p=0.024). BMI and body weight was significantly decreased (p=0.030 and p=0.020, respectively). Lipid profile biomarkers and fating blood glucose did not change significantly but triglyceride level was significantly decreased (p=0.006) in the intervention group. Conclusion: The obtained results indicate that zinc supplementation improves BMI, body weight, and triglyceride concentration without considerable effects on lipid profile and glucose level. Zinc can be suggested as a suitable supplementation therapy for obese people, but more studies are needed to verify the results.

Adv Pharm Bull. 2013;3(1):161-5

Zinc deficiency induces dysregulation of cytokine productions in an experimental colitis of rats.

Dextran sulfate sodium (DSS)-induced colitis is an experimental model of ulcerative colitis, although the precise mechanism has not yet been elucidated. We investigate whether Zn deficiency affects the pathogenesis of colitis induced by DSS with a focus on immune responses. Male WKAH/Hkm Slc rats were fed either a Zn-adequate (ZA, 30 mg Zn/kg diet) as a control or Zndeficient (ZD, 5 mg Zn/kg diet) diet for 21 days and then treated with 2% DSS via deionized drinking water for 7 days. The disease activity index (DAI) was recorded daily throughout DSS treatment. Serum Zn concentrations were significantly lowered in rats fed the ZD diet than those fed the ZA diet at day 7 and 14. Surprisingly, DSS treatment considerably reduced the serum Zn in both groups. The rats fed the ZD diet showed exacerbated colitis based on clinical outcomes, including weight loss, increased DAI, and shortened colon length. An in vitro study corroborated these results, showing that a large amount of TNFa was induced by rat mesenteric leukocytes in response to lipopolysaccharide in ZD medium, but not in ZA medium. These results indicate that a modulation of TNFa production due to Zn deficiency influences disease activity in DSS-induced colitis. In addition, more attention should be given to Zn for prevention of colitis.

Biomed Res. 2012 Dec;33(6):329-36

Studies on zinc in wound healing.

Topical zinc is widely used in wound treatment although the beneficial effect of zinc has only been documented in zinc-deficient patients who were given zinc orally. The main purpose of this study was to investigate the effect of topically applied zinc on leg ulcer healing and examine its effect on some mechanisms in wound healing using standardized animal models. Additionally, absorption of zinc into wounds and intact skin treated topically with zinc was studied. In a double-blind trial involving 37 leg ulcer patients with low serum zinc levels, topical zinc oxide promoted cleansing and re-epithelialization. Infections and deteriorations of ulcers were less common in zinc oxide treated patients. Re-epithelialization, an important mechanism in the closure of leg ulcers, was enhanced with zinc oxide applied topically on partial-thickness wounds in pigs with normal zinc status. Zinc sulfate at three different concentrations did not, however, result in this beneficial effect on the resurfacing of wounds. The inflammatory reaction was diminished in zinc treated wounds except when a high zinc sulfate concentration was applied. Bacterial growth and concomitant diseases such as diabetes can complicate wound healing. In normal rats, bacterial growth in full-thickness wounds was reduced with topical zinc oxide but not in hyperglycemic diabetic rats. The anti-bacterial mechanism of zinc oxide seemed to be more indirect and to be mediated via local defense systems rather than being directly toxic to the bacteria. Healing of 21-day-old skin incisions was impaired in zinc deficiency, as measured by a significantly decreased wound breaking strength in zinc-deficient rats compared with that of pair-fed controls. The decreased breaking strength did not seem to be due to differences in collagen concentration of the wounds. Zinc oxide was slowly but continuously solubilized when applied on open wounds in rats. On the other hand, with zinc sulfate, the zinc concentrations, either locally or systemically, did not maintain a constant level for the 48-hour post-operative treatment period as they did with zinc oxide. Zinc absorption in and through normal human forearm skin was demonstrated after treatment with a zinc oxide medicated occlusive dressing by increased zinc levels in epidermis, interstitial fluid and dermis compared with the non-zinc control dressing. In conclusion, topical zinc may stimulate leg ulcer healing by enhancing re-epithelialization, decreasing inflammation and bacterial growth. When zinc is applied on wounds it not only corrects a local zinc deficit but also acts pharmacologically.

Acta Derm Venereol Suppl (Stockh). 1990;154:1-36

CD4+ T-cell responses to an oral inactivated cholera vaccine in young children in a cholera endemic country and the enhancing effect of zinc supplementation.

Immunization of young children with the oral inactivated whole cell cholera vaccine Dukoral((R)) containing recombinant cholera toxin B subunit (CTB) induces antibody responses which can be further enhanced by zinc supplementation. We have investigated if immunization with the cholera vaccine induces specific T-cell responses in young children and also whether zinc supplementation influences these responses. Bangladeshi children (10-18 months old) received vaccine alone, vaccine together with zinc supplementation or only zinc. T-cell blast formation indicating a proliferative response was analyzed by the flow cytometric assay of cell-mediated immune response in activated whole blood (FASCIA) and cytokines were measured by ELISA. Stronger T-cell responses were detected if a modified CTB molecule (mCTB) with reduced binding to GM1 ganglioside was used for cell stimulation compared to normal CTB. After vaccination, CD4+ T cells responded to mCTB with significantly increased blast formation (P<0.01) and IFN-gamma production (P<0.05) compared to before vaccination. No responses to mCTB were detected in children receiving zinc alone (P>0.05). The IFN-gamma production was significantly higher (P<0.01) but the blast formation comparable (P>0.05) in children receiving zinc plus vaccine compared to in children receiving vaccine alone. The vibriocidal antibody responses induced by the vaccine were also significantly higher in children receiving zinc supplementation (P<0.001). Our results thus show that oral cholera vaccination induces a Th1 T-cell response in young children, and that the IFN-gamma as well as the vibriocidal antibody responses can be enhanced by zinc supplementation.

Vaccine. 2009 Dec 11;28(2):422-9

Zinc: dietary intake and impact of supplementation on immune function in elderly.

The diet in the elderly does not provide a sufficient level of nutrients needed to maintain an adequate healthy status leading to micronutrient deficiencies and impaired immune response with subsequent development of degenerative diseases. Nutrient “zinc” is a relevant micronutrient involved in maintaining a good integrity of many body homeostatic mechanisms, including immune efficiency, owing to its requirement for the biological activity of many enzymes, proteins and for cellular proliferation and genomic stability. Old people aged 60-65 years and older have zinc intakes below 50% of the recommended daily allowance on a given day. Many causes can be involved: among them, altered intestinal absorption, inadequate mastication, psychosocial factors, drugs interactions, altered subcellular processes (zinc transporters (Zip and ZnT family), metallothioneins, divalent metal transporter-1). Zinc supplementation may remodel the immune alterations in elderly leading to healthy ageing. Several zinc trials have been carried out with contradictory data, perhaps due to incorrect choice of an effective zinc supplementation in old subjects showing subsequent zinc toxic effects on immunity. Old subjects with specific IL-6 polymorphism (GG allele carriers; named C-) are more prone for zinc supplementation than the entire old population, in whom correct dietary habits with foods containing zinc (Mediterranean diet) may be sufficient in restoring zinc deficiency and impaired immune response. We summarise the main causes of low zinc dietary intake in elderly reporting an update on the impact of zinc supplementation upon the immune response also on the basis of individual IL-6 polymorphism.

Age (Dordr). 2013 Jun;35(3):839-60

Zinc and regulation of inflammatory cytokines: implications for cardiometabolic disease.

In atherosclerosis and diabetes mellitus, the concomitant presence of low-grade systemic inflammation and mild zinc deficiency highlights a role for zinc nutrition in the management of chronic disease. This review aims to evaluate the literature that reports on the interactions of zinc and cytokines. In humans, inflammatory cytokines have been shown both to up- and down-regulate the expression of specific cellular zinc transporters in response to an increased demand for zinc in inflammatory conditions. The acute phase response includes a rapid decline in the plasma zinc concentration as a result of the redistribution of zinc into cellular compartments. Zinc deficiency influences the generation of cytokines, including IL-1b, IL-2, IL-6, and TNF-a, and in response to zinc supplementation plasma cytokines exhibit a dose-dependent response. The mechanism of action may reflect the ability of zinc to either induce or inhibit the activation of NF-kB. Confounders in understanding the zinc-cytokine relationship on the basis of in vitro experimentation include methodological issues such as the cell type and the means of activating cells in culture. Impaired zinc homeostasis and chronic inflammation feature prominently in a number of cardiometabolic diseases. Given the high prevalence of zinc deficiency and chronic disease globally, the interplay of zinc and inflammation warrants further examination.

Nutrients. 2012 Jul;4(7):676-94