Table 2.
Effects of dysregulated gut microbiota on the immune status and COVID-19 progression.
| Microbial change | Potential effect | Outcome | Reference |
|---|---|---|---|
| ↑Acinetobacter, Rhodococcus | Inversely correlate with CD3, CD4, CD45, haemoglobins and RBC | Promote COVID-19 severity | (20) |
| ↓Bacteroides, Veillonella | Positively correlate with CD3, haemoglobins and RBC | Lessen COVID-19 severity | |
| ↓Enterococcus | Positively correlate with the plasma concentration of carbon dioxide | Lessen COVID-19 severity | |
| ↑Eubacterium dolichum, Prevotella copri | Positively correlate with SARS-CoV-2 viral load | Promote COVID-19 severity | (30) |
| ↓Alistipes, Bifidobacterium, Clostridium citroniae, Dialister, Haemophilus, Haemophilus parainfluenzae, Ruminococcus, Streptococcus anginosus | Inversely correlate with SARS-CoV-2 viral load | Lessen COVID-19 severity | |
| ↑Actinomyces viscosus, Bacteroides nordii, Clostridium hathewayi | Induce bacteremia | Promote COVID-19 severity | (31) |
| ↑Coprobacillus, Clostridium hathewayi, Clostridium ramosum | Positively correlate with COVID-19 severity | Promote COVID-19 severity | |
| ↓Alistipes onderdonkii, Faecalibacterium prausnitzii | Inversely correlate with COVID-19 severity | Lessen COVID-19 severity | |
| ↑Alistipes finegoldii, Clostridium innocuum, Ruthenibacterium lactatiformans | Positively correlate with inflammatory biomarkers CRP and WBC | Promote COVID-19 severity | (32) |
| ↓Alistipes putredinis, Blautia luti, Dorea longicatena, Faecalibacterium prausnitzii, Gemmiger formicilis | Inversely correlate with COVID-19 severity | Lessen COVID-19 severity | |
| ↑Bacteroides | Positively correlate with COVID-19 severity | Promote COVID-19 severity | (33) |
| ↓Bifidobacterium, Roseburium | Inversely correlate with COVID-19 severity | Lessen COVID-19 severity | |
| ↑Aspergillus | Positively correlate with COVID-19 severity | Promote COVID-19 severity | (34) |
| ↑Blautia, Lactobacillus, Ruminococcus | Positively correlate with proinflammatory cytokines IFN-γ, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α | Magnify inflammation | (35) |
| ↓Bacteroides, Clostridiales, Streptococcus | Inversely correlate with proinflammatory cytokines IFN-γ, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α | Inhibit inflammation | |
| ↑Burkholderia contaminans | Positively correlate with inflammation biomarkers CRP and IL-6; inversely correlate with the levels of lymphocytes, CD3+ T cells and CD4+ T cells | Magnify inflammation; impair adaptive immune responses | (36) |
| ↑Enterococcus faecalis | Inversely correlate with the count of CD8+ T cells | Impair adaptive immune responses | (37) |
| ↓Lachnospira, Prevetolla, Roseburia | Inversely correlate with IL-21 | Inhibit inflammation | (38) |
| ↑Akkermansia muciniphila, Bacteroides dorei | Positively correlate with IL-6, CXCL8 and IL-1β | Magnify inflammation | (39) |
| ↓Bifidobacterium adolescentis, Collinsella aerofaciens, Coprococcus comes, Dorea longicatena, Eubacterium rectale, Faecalibacterium prausnitzii | Inversely correlate with CXCL10 | Inhibit inflammation | |
| ↓Collinsella aerofaciens, Coprococcus comes, Dorea formicigenerans, Dorea longicatena, Ruminoccocus obeum | Inversely correlate with IL-10 | Inhibit inflammation | |
| ↓Collinsella aerofaciens, Coprococcus comes | Inversely correlate with TNF-α | Inhibit inflammation | |
| ↓Coprococcus comes, Eubacterium rectale | Inversely correlate with CCL2 | Inhibit inflammation | |
| ↓Clostridia | Inversely correlate with IFN-γ | Inhibit inflammation | (40) |
| ↑Actinobacteria | Positively correlate with the gp130/sIL-6Rb level | Magnify inflammation | |
| ↑Citrobacter, Fusobacterium, Peptostreptococcus | Positively correlate with faecal IL-18 level | Facilitate the cytokine storm | (41) |
| ↑Enterococcus faecalis (GroEL) | Positively correlate with IL-6 and IL-10 | Facilitate the cytokine storm | (37) |
| ↑Eubacterium ramulus | Inversely correlate with IL-6 | Prevent the cytokine storm | |
| ↑Blautia obeum, Coprococcus catus, Coprococcus comes | Positively correlate with the number of lymphocytes, CD3+ T cells, CD4+ T cells and CD8+ T cells and lymphocyte proportion | Enhance adaptive immune responses | (42) |
| ↓Roseburia intestinalis | Positively correlate with the number of lymphocytes, CD3+ T cells, CD4+ T cells and CD8+ T cells and lymphocyte proportion | Enhance adaptive immune responses |
↑ represents high abundance; ↓ represents low abundance.