COVID-19 and gut immunomodulation

Figure 1 COVID-19 and gut Immunomodulation. A: Model is showing gut infection; B: Zoomed in area of the gut; C: Zoomed in representation of an area showing the intestinal crypts; D: Zoomed in C, showing a histological representation of intestinal crypts. The intestinal epithelium is folded and organized into crypts and villus. Villus is the finger-like projections gutting out towards the lumen of the intestine (red cells). The crypts base (shown in yellow and green cells) houses the intestinal stem cells, while the blue cells comprise the transit-amplifying cells. SARS-CoV-2 activates angiotensin-converting enzyme 2 receptors, and epithelial cell death-associated release of damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). DAMPs and PAMPs are considered a danger signal by immune cells, especially the dendritic cells, macrophages, and innate immune cells. This damage recognition is associated with proinflammatory cytokine production (like Interferon, tumor necrosis factor-α), followed by immune infiltration and virus-specific B and T cell response. CD8+ T cells undergo clonal expansion and kill the infected cells and launch an antiviral attack. B cells differentiation to plasma cells can lead to antiviral antibody production and subsequent neutralization of SARS-CoV-2[10,14]. Some images (Free Stock Media) are downloaded from Canva.com using subscription. IFN: Interferon; TNF-α: Tumor necrosis factor-α; DAMP: Damage-associated molecular patterns; PAMP: Pathogen-associated molecular patterns; DC: Dendritic cells; MQ: Macrophages.