SARS-CoV-2 infection causes intestinal cell damage: Role of interferon's imbalance

Abstract

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative agent of the newly emerging lung disease pandemic COVID-19. This viral infection causes a series of respiratory disorders, and although this virus mainly infects respiratory cells, the small intestine can also be an important site of entry or interaction, as enterocytes highly express in angiotensin-2 converting enzyme (ACE) receptors. There are countless reports pointing to the importance of interferons (IFNs) with regard to the mediation of the immune system in viral infection by SARS-CoV-2. Thus, this review will focus on the main cells that make up the large intestine, their specific immunology, as well as the function of IFNs in the intestinal mucosa after the invasion of coronavirus-2.

Keywords: Cytokines; Interferons; SARS-CoV-2 infection.

Fig. 1

Anatomical Parts of the Large Intestine. The large intestine is anatomically divided into appendix, cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum.

Fig. 2

Immune response of the intestinal mucosa after infection by SARS-CoV-2. Characteristics of the immunology of the intestinal mucosa under physiological conditions (A), in which there is a population of immune T cells dispersed, and these interact directly with the enterocytes, performing an essential function in local homeostasis. By invading the intestinal mucosa through ACE-2 (B), SARS-CoV-2 promotes a change in the response of immune signaling. This contributes to the hyperinflammatory process, with a “cytokine storm” profile, characterized by hyperactivation of T cells and a massive production of interleukin IL-β, IL-6, TNF-α and IFN-γ .

Fig. 3

IFNs imbalance and intestinal clinical repercussions in SARS-CoV-2 infection. From the moment that an imbalance in ECA2 occurs, the expression of the amino acid B 0 AT1 transporter is also unregulated, being responsible for controlling the uptake of tryptophan in the intestine. Therefore, there is a decrease in intestinal absorption of tryptophan and consequent deregulation of antimicrobial peptides and dysbiosis, justifying the occurrence of diarrhea in patients infected with SARS-CoV-2.