What is it about?
According to meta-analysis data, 9.8–20% of COVID-19 patients experience gastrointestinal symptoms, where diarrhoea is the most frequent, and about 50% shed viruses with high titre through their faeces, where a first faecal transmission was reported. Furthermore, gut inflammation, intestinal damage, and weakening of the gut mucosal integrity that leads to increased permeability has been shown in different studies for COVID-19 patients. This can lead to increased inflammation and bacteraemia. Low mucosal integrity combined with low intestinal damage is a good predictor for disease progression and submission to the intensive care unit (ICU). Several pilot studies have shown that the gut microbiome of COVID-19 patients is changed, microbial richness and diversity were lower, and opportunistic pathogens that can cause bacteraemia were enriched compared to a healthy control group. In a large proportion of these patients, dysbiosis was not resolved at discharge from the hospital and one study showed dysbiosis is still present after 3 months post COVID-19. Consequently, there might be a link between dysbiosis of the gut microbiome in COVID-19 patients and chronic COVID-19 syndrome (CCS). Various clinical trials are investigating the benefit of probiotics for acute COVID-19 patients, the majority of which have not reported results yet. However, two clinical trials have shown that a certain combination of probiotics is beneficial and safe for acute COVID-19 patients. Mortality was 11% for the probiotic treatment group, and 22% for the control group. Furthermore, for the probiotic group, symptoms cleared faster, and an 8-fold decreased risk of developing a respiratory failure was calculated. In conclusion, evidence is arising that inflammation, increased permeability, and microbiome dysbiosis in the gut occur in COVID-19 patients and thus provide new targets for adjuvant treatments of acute and chronic COVID-19. More research in this area is needed.
Featured Image
Photo by CDC on Unsplash
Why is it important?
Infection with SARS-CoV-2, the causative agent for COVID-19, seems to be a rather complex process, at least for patients that are administered to the hospital. It is not "just" affecting the pulmonary system, but also the cardiovascular system, renal system, hepatic system, gastrointestinal system, nervous system, and/or various systems, leading to shock and multi-organ failure. Especially difficult to treat is the overreaction of the immune system in some patients, which is known as a cytokine storm. There is some evidence showing that SARS-CoV-2 infection in the gut leads to changes in the gut microbiome, increases inflammation and weakens the gut mucosal integrity. These can lead to further inflammation, distribution of virus to other organs and increase the chances of bacteremia. Treatment of the gut could therefore be an adjuvant therapy to reduce the risk of severe disease progression. Two clinical trials are showing such effects, however, more research is needed.
Perspectives
Microbiome research has shown the immense complexity between microbes and humans. In my opinion, we are still at the beginning to understand this complexity and how it is influenced by the microbes as well as the host (humans). There is constant crosstalk not just between the microbes in one place of the body, but also between places for example the gut microbiome crosstalks with the lung microbiome. Various molecules from the microbes will go into the bloodstream and crosstalks to human cells and also to the mitochondria. On the other hand, there is crosstalk from the human cells with the microbes, so the talking is multi-directional. There is no wonder why in many diseases changes in the microbiomes are observed. Seemingly, this is also the case in COVID-19 and it could be an option to reduce the risk of disease severeness with simple and cheap interventions. In my opinion, worthwhile looking into that more.
Prof Kai Hilpert
St Georges University of London
Read the Original
This page is a summary of: Is the Gut Microbiome a Target for Adjuvant Treatment of COVID-19?, Biologics, September 2021, MDPI AG,
DOI: 10.3390/biologics1030017.
You can read the full text:
Contributors
The following have contributed to this page
