Gastrointestinal pathophysiology of SARS-CoV2 – a literature review

Abstract

SARS-CoV2 is a novel coronavirus responsible for causing COVID-19, first identified in the city of Wuhan, China and officially declared a pandemic by the World Health Organization. SARS-CoV2 expresses high affinity to human ACE2 receptors, including within the gastrointestinal tract. Patients with COVID-19 exhibit a wide spectrum of GI symptoms including anorexia, nausea, vomiting, abdominal pain, and abnormal liver function tests. Pathogenesis behind gastrointestinal symptoms caused by SARS-CoV2 has been postulated to be multifactorial including disruption of the intestinal mechanical barrier integrity, alteration of the gut microbiome and systemic inflammatory response to the virus. SARS-CoV-2 RNA has also been found in stool samples of infected patients for a significantly longer period than in nasopharyngeal samples, though the implication of this finding is unclear at this time. Liver injury in patients with COVID-19 is usually mild, stemming from immune-mediated damage, drug induced hepatotoxicity, or ischemia from sepsis. Patients with pre-existing liver disease may be at a higher risk for hospitalization and mortality. Given the high degree of infectivity of this disease, healthcare providers will need to remain watchful for resurgence of this virus. Strict protocols should be implemented regarding hand hygiene, isolation, personal protective equipment, and appropriate disposal of waste. It is also imperative to identify patients with gastrointestinal symptoms at an early stage as these patients may have a prolonged course between symptom onset and viral clearance.

Recent progress on the mutations of SARS-CoV-2 spike protein and suggestions for prevention and controlling of the pandemic

“…The composition of gut microflora in patients with COVID-19 and even recovered patients is unbalanced, which is characterized by the decrease of beneficial microbes and the increase of harmful ones ( Yeoh et al, 2021 ). These results suggest that the GI disorders caused by COVID-19 are mainly due to the destruction of intestinal mechanical barrier integrity, alteration of the intestinal microflora, and systemic inflammatory response to the virus ( Luo et al, 2021 ; Syed et al, 2020 ; Villapol, 2020 ). Therefore, it is recommended to properly add beneficial intestinal microbes, especially probiotics and prebiotics, which may enhance the intestinal barrier function, help to improve and alleviate the sequela of COVID-19 and accelerate the complete recovery of patients.…”

Environmental Determinants of Coronavirus Disease 2019 (COVID-19)

“…Notably, impaired tryptophan homeostasis in Ace2-deficient mice decreases antimicrobial peptide generation resulting in an altered intestinal microbiome [110]. With ACE2 being highly expressed in enterocytes, it is therefore not surprising that intestinal infections with SARS-CoV-2 would promote gastrointestinal symptoms like diarrhea [111].…”

COVID‑19 and SARS‑CoV‑2 host cell entry mediators: Expression profiling of TMRSS4 in health and disease

“…Moreover, a recent study demonstrated that both ACE2 and TMPRSS2 genes were abundantly expressed in enterocytes of the lower gastrointestinal (GI) tract, whilst also exhibiting co-expression with TMPRSS4, particularly in the small intestine ( 16 ). Of note, whereas COVID-19 presentation usually includes fever, cough, pulmonary/respiratory symptoms, and loss of taste and smell ( 17 , 18 ), an increasing number of studies has also reported GI-related symptoms (e.g., diarrhoea, nausea and vomiting) in patients with COVID-19 ( 19 - 21 ). Indeed, a proportion of these patients with extra-pulmonary symptoms do not exhibit other respiratory symptoms ( 22 ).…”