Coronovirus linked to the microbiome?

Researchers in China recently looked at the relation between an infection with the coronavirus and the microbiome. The coronavirus binds the cellular ACE2 receptor, allowing it to enter the cell and subsequently deplete it of its energy by multiplying; hereby destroying the cell. Coincidentally, the ACE2 receptor is also known for its role in intestinal inflammation. The researchers tried to look for a pattern in patient variables to determine any causal factors which they could use to discriminate between patients with regards to severity of an infection. They first looked at the protein composition in the blood. They determined which proteins are more prevalent in infected patients, and derived a protein-risk score from this data. They then correlated this protein risk score to the microbiome of patients, to see if there were any significant differences in the composition of the microbiome between patients who had a higher or lower protein-risk score, respectively. They found several bacterial species of the human microbiome to be related to an infection with the coronavirus, being the Bacteroides genus, Streptococcus genus, Lactobacillus genus, the Ruminococcaceae, Lachnospiraceae families and Clostridiales order. However, only the Ruminococcus genus, Blautia genus and Lactobacillus genus could be directly linked to an increased cytokine concentration in the blood, which increase the state of an infection.

In a second step, the study identified the main functional components of these bacteria, and found these to be the production of amino acids, bile acids and fatty acids. Amino acids are, amongst others, involved in the buildup of muscle tissue, whereas fatty acids are used in energy metabolism and bile acids in the degradation of food.

In conclusion, the study found a direct correlation between the obtained protein-risk-score, which denotes the severity of infection with the coronavirus, and the microbiome. However, these results should be interpreted with caution as the microbiome parameters were not the main outcome of the study, and was done on a Chinese study population.  

Source: Guo, W. et al (2020); Gut microbiota may underlie the predisposition of healthy individuals to COVID-19. medRxiv preprint. April 25, 2020.