Gastrointestinal complications caused by SARS-CoV-2

Severe Acute Respiratory Syndrome The sudden and rapid outbreak of coronavirus 2 (SARS-CoV-2) caused a pandemic of coronavirus disease 2019 (COVID-19), 6.3 million worldwide as of June 7, 2022. It is taking more lives than people. Due to the high rate of genomic mutations, several SARS-CoV-2 mutants have emerged, which are classified into mutants of interest (VOCs) and mutants of interest (VOIs).

Researchers have reported that SARS-CoV-2 affects many organs, including the lungs, stomach, and heart of infected patients.recently virus In a review, scientists discuss COVID-19-related gastrointestinal (GI) complications.

study: Gastrointestinal involvement in SARS-CoV-2 infection. Image Credits: Kateryna Kon / Shutterstock.com

SARS-CoV-2 infection and GI complications

Several studies have reported that SARS-CoV-2 primarily targets lung cells, which causes serious respiratory complications. Interestingly, many studies have also reported the presence of SARS-CoV-2 ribonucleic acid (RNA) in fecal samples of infected patients, confirming the release of SARS-CoV-2 in feces. increase.

Common gastrointestinal complications associated with COVID-19 include vomiting, loss of appetite, nausea, and diarrhea. SARS-CoV-2 infection with GI symptoms can lead to acute infections with a poor prognosis.

Gastrointestinal imaging of COVID-19 patients provides evidence of intestinal wall thickening, mesenteric thickening, fluid-filled large intestine, hyperemia, pneumonia, and rarely ischemia. Previous studies have also reported that diarrhea caused by SARS-CoV-2 infection may be due to dysfunction of the intestinal ion transporter, which causes inflammation and various GI complications.

Importantly, COVID-19 patients suffering from GI symptoms are often more likely to develop severe dyspnea. Scientists speculate that inflammatory cytokines may be associated with the pathogenesis of SARS-CoV-2 between the respiratory and digestive systems.

COVID-19 gastrointestinal tract-lung axis. ACE2, angiotensin converting enzyme 2.

In addition, patients with acute COVID-19 have more experience stomach ache Than patients with mild symptoms. However, little difference has been reported with respect to the symptoms of anorexia, vomiting, diarrhea, and nausea reported in both patient groups.

Patients suffering from gastrointestinal disorders such as thromboembolic events and mesenteric ischemia are at increased risk of death. In addition, transaminase levels in COVID-19 patients are usually very high, causing intestinal ischemia and increasing the risk of intestinal obstruction.

Previous studies have also shown that SARS-CoV-2 virions can enter the gastrointestinal tract through the esophagus. In addition, detection of SARS-CoV-2 in the feces of infected patients means that the virus was transmitted via the fecal-oral route. In summary, endoscopic sampling of the gastrointestinal tract of COVID-19 patients revealed the presence of SARS-CoV-2 RNA in the stomach, esophagus, rectum, and duodenum. SARS-CoV-2 nucleocapsid (N) protein 2 has also been detected in the cytoplasm of rectal epithelial cells and duodenal cells.

SARS-CoV-2 and gut microbiota

The presence of the virus in the gastrointestinal tract affects the health of the host because the virus interacts with the mucous layer, lamina propria immune cells, and epithelial cells. In addition, changes in the intestinal virome can have a significant impact on immune phenotype.

The intestinal flora is rich in beneficial bacteria that maintain intestinal homeostasis, suppress excessive mucosal inflammation, and promote the development of immune responses on the mucosal surface. In summary, the gut flora is composed of about 100 trillion microorganisms and thousands of bacterial species.

Adaptive and innate immune cells are caused by the disruption of the integrity of the intestinal barrier. In addition, the release of pro-inflammatory cytokines into the circulation can cause systemic inflammation. Therefore, invasion of inflammatory cells such as neutrophils and lymphocytes into the intestinal mucosa can cause serious destruction of the intestinal flora.

Changes in the composition of the intestinal flora, ie Campylobacter, increased parabacteria, Bacteroides, Bifidobacterium, Clostridium, RuminococcusRotella, Corynebacterium Pseudomonas, EnterococcusWhen AspergillusAnd significant reductions Eubacterium, Fecalibacterium, LachnospiraceaeWhen Firmicutes, Affects COVID-19 results.. Previous studies have shown that changes in the composition and function of the gut microbiota affect the airways through the general mucosal immune system. Respiratory dysbiosis also affects the gastrointestinal tract through immune regulation.

SARS-CoV-2 elicits an early neutralizing antibody response involving peripheral proliferation of immunoglobulin A (IgA) plasmablasts, systemic IgA, and systemic IgG that may be mucosal homing. A previous study reported that the intestinal lung axis plays an important role in the control of COVID-19.

Another study found that cytokines can enter the lungs through the bloodstream when the intestine becomes inflamed. This condition has a significant effect on the immune response and inflammation of the lungs.

Increased circulating pro-inflammatory cytokines can also affect the composition of the intestinal flora and can increase intestinal permeability. This causes translocations of pathogens and toxins, which can increase the severity of the disease and lead to multiple organ failure.

Changes in the intestinal flora and inflammation of the epithelium may also enhance the expression of angiotensin converting enzyme 2 (ACE2) receptors in the intestine. It is primarily used by SARS-CoV-2 for cell invasion.

In summary, little is known about the general underlying GI symptoms and the exact underlying mechanism associated with COVID-19.

Conclusion

Some COVID-19 patients suffer from GI symptoms. However, these off-target symptoms in patients infected with SARS-CoV-2 are often ignored. In the future, it is necessary to study gastrointestinal symptoms and changes in the intestinal flora in patients with COVID-19. Targeting these tissues may be effective in controlling infection.