Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis (IPF) is a lung disease marked by chronic and progressively worsening scarring (fibrosis) for which a cause is not known (idiopathic). Lung tissue surrounding the lungs' air sacs becomes fibrous and stiff, interfering with their normal movement and gas exchange and making it increasingly difficult for patients with IPF to breathe (Plantier 2018).
IPF is considered irreversible and eventually leads to fatal respiratory failure, typically within three to five years of diagnosis (Tzilas 2017), but some patients experience more rapid disease progression (Lindell 2017). There are approximately 128,000 new cases of IPF and more than 16,000 IPF-related deaths in the United States each year (Murtha 2017; Lindell 2017).
Although the cause of IPF is not precisely understood, it is currently thought to stem from the inability of cells that line lung alveoli to regenerate after repeated injury. In addition to environmental factors that cause repeated micro-injury to the alveolar lining, a genetic predisposition is thought to be involved (Frangogiannis 2016; Sgalla 2018). Aging plays a fundamental role in increasing susceptibility to both alveolar injury and dysfunctional pro-fibrotic signaling and is a major risk factor for IPF (Zank 2018).
The main symptoms of IPF are shortness of breath and cough, which gradually worsen over several years (Ferrara 2018). Computed tomography (CT) scan and lung biopsy show a pattern of fibrosis that indicates likely IPF, but a diagnosis is only secured after a rigorous search for other causes has yielded no results (Sgalla 2018).
IPF treatment is evolving along with understanding of its underlying mechanisms. New anti-fibrotic drugs—pirfenidone (Esbriet) and nintedanib (Ofev)—recently received approval for use in patients with IPF (Sharif 2017; Sathiyamoorthy 2017). Along with medications that reduce inflammation and oxidative stress, they represent the current best options in conventional treatment; unfortunately, medical approaches pose significant adverse side effects, and none have yet been shown to prolong life (Sgalla 2018). Lung transplant is the only treatment that increases the odds of survival, but is nonetheless associated with a high mortality rate and is only appropriate in select cases (Kistler 2014).
Although IPF is always progressive, new understandings about mechanisms and recent advances in diagnosis and treatment are reasons for optimism (Sgalla 2018). Emerging technologies may lead to earlier diagnosis and more rapid initiation of appropriate therapy (Tzilas 2017; Drakopanagiotakis 2018; Fois 2018). Novel treatment approaches such as mesenchymal stem cell therapy (Glassberg 2017) and the use of senolytics (ie, agents that trigger degradation of aged, dysfunctional cells) are topics of current research (Kirkland 2017). Also, the drug pentoxifylline has demonstrated some anti-fibrotic properties in animal models of pulmonary fibrosis and represents an interesting area of ongoing research (Entzian, Schlaak 1997; Kaya 2014; Naranjo 2011; Lee 2017). Proton-pump inhibitors (PPIs), usually used to treat gastroesophageal reflux, are of interest in IPF research as well. Some studies have found that they have anti-fibrotic properties, and that IPF patients even without GERD symptoms often have elevated esophageal acid levels (Lee 2011; Raghu 2006).
Nutritional and herbal supplements that reduce inflammation, inhibit oxidative lung damage, and ameliorate age-related cellular dysfunction have shown promising anti-fibrotic effects in preclinical research related to IPF. These include N-acetylcysteine (Myllarniemi 2015); omega-3 fatty acids (Zhao 2014); niacin (Nagai 1994); sulfur compounds from cruciferous and onion-family vegetables (Mojiri-Forushani 2017; Yan 2017); and polyphenols such as quercetin, resveratrol, and curcumin (Impellizzeri 2015; Mojiri-Forushani 2017). Furthermore, evidence showing that some IPF patients have lower levels of the hormone dehydroepiandrosterone (DHEA) and demonstrating its anti-fibrotic potential in isolated lung cells suggests DHEA may be helpful in cases of IPF (Mendoza-Milla 2013).