AUTHOR=Reinold Johanna , Farahpour Farnoush , Fehring Christian , Dolff Sebastian , Konik Margarethe , Korth Johannes , van Baal Lukas , Hoffmann Daniel , Buer Jan , Witzke Oliver , Westendorf Astrid M. , Kehrmann Jan 

TITLE=A Pro-Inflammatory Gut Microbiome Characterizes SARS-CoV-2 Infected Patients and a Reduction in the Connectivity of an Anti-Inflammatory Bacterial Network Associates With Severe COVID-19

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.747816

DOI=10.3389/fcimb.2021.747816

ISSN=2235-2988

ABSTRACT=<p>The gut microbiota contributes to maintaining human health and regulating immune responses. Severe COVID-19 illness is associated with a dysregulated pro-inflammatory immune response. The effect of SARS-CoV-2 on altering the gut microbiome and the relevance of the gut microbiome on COVID-19 severity needs to be clarified. In this prospective study, we analyzed the gut microbiome of 212 patients of a tertiary care hospital (117 patients infected with SARS-CoV-2 and 95 SARS-CoV-2 negative patients) using <italic>16S rRNA</italic> gene sequencing of the V3-V4 region. Inflammatory markers and immune cells were quantified from blood. The gut microbiome in SARS-CoV-2 infected patients was characterized by a lower bacterial richness and distinct differences in the gut microbiome composition, including an enrichment of the phyla Proteobacteria and Bacteroidetes and a decrease of Actinobacteria compared to SARS-CoV-2 negative patients. The relative abundance of several genera including <italic>Bifidobacterium</italic>, <italic>Streptococcus</italic> and <italic>Collinsella</italic> was lower in SARS-CoV-2 positive patients while the abundance of <italic>Bacteroides</italic> and <italic>Enterobacteriaceae</italic> was increased. Higher pro-inflammatory blood markers and a lower CD8<sup>+</sup> T cell number characterized patients with severe COVID-19 illness. The gut microbiome of patients with severe/critical COVID-19 exhibited a lower abundance of butyrate-producing genera <italic>Faecalibacterium</italic> and <italic>Roseburia</italic> and a reduction in the connectivity of a distinct network of anti-inflammatory genera that was observed in patients with mild COVID-19 illness and in SARS-CoV-2 negative patients. Dysbiosis of the gut microbiome associated with a pro-inflammatory signature may contribute to the hyperinflammatory immune response characterizing severe COVID-19 illness.</p>