COVID-19 and the gastrointestinal tract: source of infection or merely a target of the inflammatory process following SARS-CoV-2 infection?

Abstract

Gastrointestinal (GI) symptoms have been described in a conspicuous percentage of coronavirus disease 2019 (COVID-19) patients. This clinical evidence is supported by the detection of viral RNA in stool, which also supports the hypothesis of a possible fecal-oral transmission route. The involvement of GI tract in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is corroborated by the theoretical assumption that angiotensin converting enzyme 2, which is a SARS-CoV-2 target receptor, is present along the GI tract. Studies have pointed out that gut dysbiosis may occur in COVID-19 patients, with a possible correlation with disease severity and with complications such as multisystem inflammatory syndrome in children. However, the question to be addressed is whether dysbiosis is a consequence or a contributing cause of SARS-CoV-2 infection. In such a scenario, pharmacological therapies aimed at decreasing GI permeability may be beneficial for COVID-19 patients. Considering the possibility of a fecal-oral transmission route, water and environmental sanitation play a crucial role for COVID-19 containment, especially in developing countries.

The Role of the Oral Microbiota in the Etiopathogenesis of Oral Squamous Cell Carcinoma

“…The immune system ascertains that most infections caused by viruses or bacteria are self-limiting [ 125 , 126 ]. Yet, as the human immune system also contributes to the acquisition of nutrition from the human microbiota, overnutrition may occur if one eats normally without restriction [ 127 , 128 ]. This overnutrition may cause lipotoxicity and tissue damage [ 129 , 130 ], which may promote chronic inflammation, fuel microbial dysbiosis (excessive growth of certain microorganisms), and lead to chronic diseases including cancer [ 128 , 131 ].…”

SARS-CoV-2-Induced Gut Microbiome Dysbiosis: Implications for Colorectal Cancer

“…In a state of gut dysbiosis, a transient nutritional supply excess may occur, as both the microorganisms and the damaged host tissue will be degraded and become a possible source of nutrition. This may promote hyper inflammation during acute infection [ 83 ] and possibly lead to chronic diseases, such as cancer [ 84 ]. For example, some of the excess nutrition from damaged tissue, together with the excess nutrition from a dysbiotic gut microbiome, could be turned into lipid intermediates, causing lipotoxicity and further tissue damage [ 85 ].…”

Salivary Microbiome Diversity in Kuwaiti Adolescents with Varied Body Mass Index—A Pilot Study

“…The immune system has evolved to manage the microorganisms inside and around the human body for nutrition and against possible damage made by those microorganisms [26,27]. Due to the immune reactions such as phagocytosis and xenophagy [28], the human microbiome becomes the prey of human immunity and directly provides essential nutrients to the human body [29], and microbial dysbiosis (the overgrowth of any microbial species at any site of the human body) is the direct cause of the host's inflammatory and metabolic disorders [30]. Hence, we conducted this NGS-based pilot study to understand the salivary microbial diversity in Kuwaiti adolescents enrolled in a longitudinal study.…”