Reduced fungal diversity in lungs can cause ARDS, a life threatening respiratory condition linked to COVID-19

Acute respiratory distress syndrome is a potentially fatal condition characterised by inflammation in the lungs, leading to lung damage and hypoxemia (the reduced ability of lungs to pass oxygen into the blood). The condition can occur due to any type of lung injury including trauma, inhalation of chemicals or septic shock (a condition that occurs due to a systemic infection). ARDS is one of the conditions associated with COVID-19. If a patient develops ARDS, they require oxygen therapy or ventilation to provide them with breathing support. Now, a group of researchers led by Ms Noel Britton, a PhD candidate at the University of Pittsburgh claim that it might be the lack of fungal diversity in lungs that could put a person at risk of severe ARDS. The findings of the study were reported in the virtual European Respiratory Society International Congress. Human microbiome The microbiome refers to all the microbes (bacteria, viruses and fungi) living on and inside the body. So far, researchers have mostly focussed on the gut microflora and its effects on the body. The gut microbiota has been linked to immunity, risk of various diseases and, of course, digestion among others. However, since not many microbes are present in the lungs, it has been hard to isolate lung microbes and identify them. Explaining the problem with lung microbes, Britton reportedly said, “In terms of numbers of cells, fungi are outnumbered by bacteria by several orders of magnitude…while it is now well established that the lungs play host to a distinct and dynamic microbiome, they don’t represent a rich environment for microbes to thrive, and they generally have many fewer microbes than the gut.” The research was done keeping in mind the fact that fungi play an important role in activating the immune system. Since nobody yet knows why some people develop ARDS and some don’t, it is possible that fungi may have a role in it. The study The study was reportedly done in over 200 patients between October 2011 and September 2019 and then carried on into the pandemic with COVID-19 patients. About 21 percent of all patients had ARDS and about 61 percent of them were women. Out of the samples, about 100 different fungi were obtained from severely ill patients who were on mechanical ventilation. As expected, not a huge variety of fungi were present in any one sample and in some samples one fungi dominated and others were present in even fewer numbers. The diversity in these samples was much lower than in healthy humans. Most of the patients had only one type of fungus — Candida —  dominating their lung microbiome — with over 50 percent of all fungi. Candida is known to cause various diseases in humans including oral thrush, vaginal infection and the rare candida pneumonia. This decreased diversity was also associated with increased levels of a protein called pentraxin-3, which is known to be a marker of inflammation and severe disease. Explaining the source of fungal diversity in lungs, the authors of the study reportedly stated that the air has 50,000 fungal spores per cubic meter. These spores include both pathogenic and non-pathogenic fungi and enter our lungs when we breathe. It is important to note that more studies would still be needed to confirm the findings of this study and to establish how it affects patients. For more information, read our article on Acute respiratory distress syndrome. Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.