Why are Transplanted Organs Rejected?
Organ transplantation involves surgically replacing a failing organ with a healthy donor organ. Transplants offer a great solution for many patients with organ failure and can improve their lifespan and quality of life. However, donor organs are often rejected by the host's (recipient's) immune system. The immune system recognizes that the new tissue is foreign, causing an inflammatory attack on the new tissue which if not stopped results in failure of the transplanted organ.
Multiple inflammatory cytokines stimulate cytotoxic T cells to attack the transplanted organ while simultaneously inhibiting the action of protective T regulatory cells. Conventional treatments help suppress the immune system and protect the transplanted organ; however, they often have severe side effects. Importantly, certain immunosuppressive drugs also reduce the amount of T regulatory cells in circulation, preventing the immune system from developing tolerance to the new organ.
Natural interventions such as curcumin and omega-3 fatty acids may help lessen the inflammatory immune response and promote more successful transplant tolerance.
What Conventional Medical Treatments Help Prevent Organ Transplant Rejection?
- Immunosuppressive drugs (eg, calcineurin inhibitors [eg, cyclosporine])
What Natural Interventions May Be Beneficial for Organ Transplantation?
- Curcumin. Curcumin, a component of the spice turmeric, is a potent anti-inflammatory agent. Numerous studies demonstrate curcumin's ability to inhibit inflammatory cytokines involved in transplant rejection. An animal study showed mice that had heart transplants survived significantly longer when treated with an immunosuppressive drug in combination with curcumin than the drug alone.
- Omega-3 fatty acids. Omega-3 fatty acids found in fish oil, known for their anti-inflammatory properties, also suppress cytokines involved in transplant rejection. Many studies demonstrate their beneficial effects, including a study where kidney transplant patients supplemented with fish oil experienced better recovery of renal function after a rejection episode than control patients.
- Resveratrol. Resveratrol has been shown to inhibit the activity of multiple inflammatory cytokines. Animals who received a genetically incompatible liver transplant had reduced levels of cytotoxic T cells and survived significantly longer when supplemented with resveratrol.
- Quercetin. Quercetin is known to modulate the action of several inflammatory cytokines. In combination with vitamin E, quercetin has been shown in vitro to combat the hepatotoxic effects of cyclosporine, a common immunosuppressive drug. Quercetin also inhibited T-cell proliferation, suggesting it may be effective in reducing transplant rejection.
- Vitamin D. Researchers investigating the importance of vitamin D on transplant success found heart transplant patients with the lowest blood levels of the active form of vitamin D (1,25-dihydroxy vitamin D) were over 8 times as likely to die one year post transplant than those with the highest levels.
- Grape seed extract. The ratio of protective T regulatory cells to Th17 cells, T cells that are particularly aggressive, is associated with the likelihood of transplant tolerance. Grape seed extract has been shown to alter the ratio favorably and modulate immune response.
- Higher homocysteine levels have been shown to be associated with increased mortality after transplantation. Several natural interventions can lower homocysteine levels, including B complex vitamins (vitamins B6, B12, and folate) and N-acetylcysteine.
- Polyphenols. Polyphenols, such as those found in green and black tea, cocoa, and pomegranate, have cardioprotective effects that may be beneficial after organ transplantation.
- Other natural interventions that may benefit transplant patients include coenzyme Q10, vitamins C and E, L-arginine, probiotics, and magnesium.