The composition of the gut microbiome could partially explain the difference in susceptibility of COVID-19 patients, according to a new study. As more evidence gathers on the gut microbiota’s role in this disease, it will lead to effective diagnostic, prognostic and therapeutic options
SARS-Cov-2 primarily causes lung infection through binding of ACE2 receptors present on the alveolar epithelial cells, yet it was recently reported that SARS-CoV-2 RNA was found in the faeces of infected patients, according to various studies conducted across the world. Interestingly, the intestinal epithelial cells, particularly the enterocytes of the small intestine also express ACE2 receptors. A new study published on the preprint server medRxiv in April 2020 suggests that the composition of the gut microbiome could partially explain the difference in susceptibility. This adds a new dimension to what is currently known about the disease. It explains the role of gut microbiota in influencing lung diseases.
In a recent conversation with Dr Debojyoti Dhar, Co-founder and Director, Leucine Rich Bio, PhD, Indian Institute of Science, we were able to articulate some findings from similar research work happening in India. Dr Dhar’s startup, Leucine Rich Bio has been in the field of the microbiome in South Asia and have been studying the gut microbiota in detail for the past few years. Their studies on this field led them to important insights on the role of the gut microflora in various diseases. They also studied the possible role probiotics and prebiotics might play in health and disease. As Dr Dhar has published an article in Virus research journal. He and his team looked at the so-called “gut-lung axis,” role of gut microbiota in immunity and role of functional food including prebiotics and probiotics in infection and immunity.
Gut microbiota and the gut-lung axis
According to this several studies in this area, the composition of the gut microbiome could partially explain the difference in susceptibility among COVID-19 patients. Dr Dhar explains further, “The most vulnerable group of the society to COVID-19 has been the elderly, immune-compromised people and patients with co-morbidities like type 2 diabetes, hypertension etc. It is quite established that the gut microflora of these individuals has a different profile as compared to the healthy. This microbial imbalance or dysbiosis has been studied in depth in many such conditions. Secondly, it is also known that with age, gut diversity is decreased. This, along with gut dysbiosis, can tilt the balance of the gut microflora towards a “non-healthy” state which might affect the vulnerability of such patients to various infections including Covid-19.”
Many studies confirm that the gut microbiota plays a key role in health through its protective, trophic and metabolic actions. “To my knowledge, no major study has been published which profiles gut microbiota of COVID-19 patients as this is a novel virus-mediated disease. However, a small case series from China revealed that some patients with COVID-19 showed microbial dysbiosis,” informs Dr Dhar.
The basis of these studies
There are few cues that suggested a possible gut microbiota link to COVID-19. “The first one was the presence of the SARS-Cov2 viral RNA or even live virus in the faeces of many of the affected patients. Secondly, the various gastrointestinal symptoms in many patients. Thirdly, the fact that the most vulnerable were the elderly, immune-compromised patients and patients with other co-morbidities. In all such people, gut dysbiosis and decreased gut diversity (especially in the elderly) have been observed. Fourth, earlier research had suggested gut microbiota link to lung infections. So, all the above factors pointed to a possible role gut microbiota might play in this disease as well,” Dr Dhar expounds.
So, how complex is the relationship and to what extent can this become severe?
“There is now ample evidence that COVID-19 has some connection to the gastrointestinal tract as many patients show gastrointestinal symptoms and viral RNA or even live virus has been found in the faces of many such patients. In fact, a research that is still under review and is available in a preprint server (Medrxiv) suggests that COVID-19 severity may be linked to the gut microbiota,” highlights Dr Dhar. However, he is positive.
The PRS findings (medRxiv in April 2020)
According to this study, the composition of the gut microbiome could partially explain the difference in susceptibility of COVID-19 patients. “The researchers defined a set of blood-based proteomic markers that might predict the severability of COVID-19 in patients and they called it a Proteomic Risk Score (PRS). They found that as the PRS increased by 10 per cent, the risk of severe disease went up by 57 per cent. The researchers further analysed the gut microflora and found a superior correlation between the gut microflora and the PRS predicting severe COVID-19,” he apprises.
Effectiveness of the data for the future
Dr Dhar shares that many researchers are now investigating the possible link of the gut microbiota in COVID-19. In fact, leading British scientists have urged the UK Government to examine the gut microbiota’s role in COVID-19. As more evidence gathers on the gut microbiota’s role in this disease, it will lead to effective diagnostic, prognostic and therapeutic options. Also, in Dr Dhar’s article, which is published in Virus Research, he proposed gut microbiota-based personalised supplements that might aid in quicker recovery of patients.