Intestinal studies show immunosuppressive effects of COVID-19

Gut Feeling

Intestinal specimens taken from patients who have died from COVID-19 infections demonstrate how the disease has had an effect on the immune system in the gut.

Research presented by Frontiers in Immunology journal (Silvia C. Trevelin, Suzanne Pickering, Katrina Todd, Cynthia Bishop, Michael Pitcher, Jose Garrido Mesa, Lucia Montorsi, Filomena Spada, Nedyalko Petrov, Anna Green, Manu Shankar-Hari, Stuart J.D. Neil, Jo Spencer. Disrupted Peyer’s Patch Microanatomy in COVID-19 Including Germinal Centre Atrophy Independent of Local Virus. Frontiers in Immunology, 2022; 13 DOI: 10.3389/fimmu.2022.838328), performed by scientists at King’s College, London, and financed by Medica Research Council and the United Kingdom Coronavirus Immunology Consortium has shown that lymphatic tissue in the intestines, which normally acts to control the types and numbers of resident bacterial flora, is degraded in COVID-19 patients.

Peyer’s Patches, follicles of lymphatic tissue in the lining of the small intestine, normally produce cells that propagate antibodies, which in turn, regulate the gut bacterial flora. In COVID-19 patients these follicles are damaged, leading to reduced immune function. This, in turn, leads to harmful changes in the gut bacteria, “dysbiosis.”

Dysbiosis leads to diarrhea, nausea and vomiting, a COVID-19 symptom syndrome apart from the usual respiratory problems. 

Professor Jo Spencer of King’s College, said, “This study shows that in severe COVID-19 this very component of the immune system is disrupted. Whether the intestine itself is infected with SARS COV2 or not, this would likely contribute to the disturbances in intestinal microbiology in COVID-19. In the future it will be important to understand factors driving such lymphatic tissue dysregulation in severe inflammatory responses.”

Researchers also noted that the findings suggest that oral vaccination may not be effective if the patient is already ill, as the gut immune system is already compromised.

In related research led by Harvard Medical School and other institutions, including MassGeneral Hospital for Children and Brigham and Women’s Hospital, it was found that SARS-COV-2 particles that stay in the gut after a COVID-19 infection can move into the circulatory system and reach the heart, liver and other organs. This is called Multisystem Inflammatory Syndrome in Children (MIS-C).

In addition to gastrointestinal symptoms, the syndrome includes severe cardiac inflammation, a “cytokine storm.” Long hospitalizations, including treatment with steroids and immunoglobulins, are necessary for 80 percent of the children with MIS-C.

Lael Yonker, lead investigator of the study, said, “When we realize that 95 percent of the children with MIS-C has SARS-COV-2 viral particles in their noses and throats, we investigated further and found that viral material living in the gut could lead to MIS-C coinciding with the inflammatory response.”

MIS-C occurs in less than 1 percent of children with confirmed SARS-CoV-2 infection. As of May 3, 2021, the U.S. Centers for Disease Control and Prevention reported 3,742 children diagnosed with MIS-C and 35 deaths. U.S. statistics are skewed heavily toward Latino and Black children, with a total of 63 percent in cases with race or ethnicity listed.