Published online Nov 28, 2022. doi: 10.3748/wjg.v28.i44.6282
Peer-review started: September 2, 2022
First decision: September 30, 2022
Revised: September 30, 2022
Accepted: November 17, 2022
Article in press: November 17, 2022
Published online: November 28, 2022
Although some observations provide evidence for intestinal infection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the mechanisms leading to this infection are not known.
The detection of viral RNA in gastrointestinal (GI) tissue samples has not been adequately investigated and results are conflicting. More GI tissue samples, comprehensive autopsy and surgical specimens are needed to provide histological evidence of intestinal infection.
Intestinal mucosal samples from mild-moderate coronavirus disease 2019 (COVID-19) patients were analyzed with the primary objective of detecting SARS-CoV-2 RNA and evaluating histological features.
This is a monocentric trial in which real time reverse transcriptase-polymerase chain reaction and histological features were used to detect SARS-CoV-2 RNA in intestinal mucosal samples. The study population was composed of two groups of patients hospitalized for COVID-19. In the first group (biopsy group), the patients were eligible for inclusion if they had mild to moderate disease and if they agreed to have a rectal biopsy regardless of the presence or absence of GI symptoms; in the second group (surgical specimen group), patients were eligible for inclusion if they underwent intestinal resection during index hospitalization. The data obtained in this study are valuable because rectal biopsies were carried out on 30 patients who did not need the procedure to frame their disease status. The study therefore provides data that are not only more numerous but also qualitatively different from those available up to now.
Overall, we analyzed 53 rectal biopsies and 6 surgical specimens. Viral RNA was not detectable in any of the rectal biopsies performed (0/53). Histological examination showed no enterocyte damage, but slight edema of the lamina propria with mild inflammatory lymphoplasmacytic infiltration. Viral RNA was detected in 2 surgical specimens of the 6 examined, both of which were from patients with active neoplastic disease. Histological examination also pointed out abundant macrophages, granulocytes and plasma cells infiltrating the muscular layer and adipose tissue, and focal vasculitis.
Mild-moderate COVID-19 may not be associated with rectal infection by the virus. Although the present data are unable to support the observations suggesting that enteric infection can occur in COVID-19 patients, the detection of the viral RNA observed and the inflammatory cell infiltration to the colonic tissue of patients with active cancer could serve as hypothesis generators, leading to the analyzing more comprehensive autopsy or surgical specimens in order to assess the potential link between SARS-CoV-2 and enteric infections in this population.
Does intestinal infection lead to increased expression of inflammatory cytokines in the intestine and/or serum? Since the two positive samples were both from patients with active cancer, could a weakened immune system, induced by the neoplastic disease, increase the risk of the intestinal infection of SARS-CoV-2?