Cause and effect, or simply coincidental?
Some insight into MIS-C pathogenesis was provided by Lael M. Yonker, MD, and colleagues in their analysis of biospecimens from 100 children: 19 with MIS-C, 26 with acute COVID-19, and 55 controls. They demonstrated that in children with MIS-C the prolonged presence of SARS-CoV-2 in the GI tract led to the release of zonulin, a biomarker of intestinal permeability, with subsequent trafficking of SARS-CoV-2 antigens into the bloodstream, leading to hyperinflammation. They were then able to decrease plasma SARS-CoV-2 spike antigen levels and inflammatory markers, with resulting clinical improvement after administration of larazotide, a zonulin antagonist.
These observations regarding the potential mechanism and triggers of MIS-C may offer biomarkers for early detection and/or strategies for prevention and treatment of MIS-C.
Bottom line
The GI tract is the target of an immune-mediated inflammatory response that is triggered by SARS-CoV-2, with MIS-C being the major manifestation of the resultant high degree of inflammation. These observations will allow an increased awareness of nonrespiratory symptoms of SARS-CoV-2 infection by clinicians working in emergency departments and primary care settings.
Clues that may enhance the ability of pediatric clinicians to recognize the potential for severe GI involvement include the occurrence of abdominal pain, leukopenia, and elevated inflammatory markers. Their presence should raise suspicion of MIS-C and lead to early evaluation.
Of note, COVID-19 mRNA vaccination is associated with a lower incidence of MIS-C in adolescents. This underscores the importance of COVID vaccination for all eligible children. Yet, we clearly have our work cut out for us. Of 107 children with MIS-C who were hospitalized in France, 31% were adolescents eligible for vaccination; however, none had been fully vaccinated. At the end of 2021, CDC data noted that less than 1% of vaccine-eligible children (12-17 years) were fully vaccinated.
The Pfizer-BioNTech vaccine is now authorized for receipt by children aged 5-11 years, the age group that is at highest risk for MIS-C. However, despite the approval of vaccines for these younger children, there is limited access in some parts of the United States at a time of rising incidence.
We look forward to broad availability of pediatric vaccination strategies. In addition, with the intense focus on safe and effective therapeutics for SARS-CoV-2 infection, we hope to soon have strategies to prevent and/or treat the life-threatening manifestations and long-term consequences of MIS-C. For example, the recently reported central role of the gut microbiota in immunity against SARS-CoV-2 infection offer the possibility that “microbiota modulation” may both reduce GI injury and enhance vaccine efficacy.
Dr. Balistreri has disclosed no relevant financial relationships.
William F. Balistreri, MD, is the Dorothy M.M. Kersten Professor of Pediatrics; director emeritus, Pediatric Liver Care Center; medical director emeritus, liver transplantation; and professor, University of Cincinnati College of Medicine, department of pediatrics, Cincinnati Children’s Hospital Medical Center. He has served as director of the division of gastroenterology, hepatology, and nutrition at Cincinnati Children’s for 25 years and frequently covers gastroenterology, liver, and nutrition-related topics for this news organization. Dr Balistreri is currently editor-in-chief of the Journal of Pediatrics, having previously served as editor-in-chief of several journals and textbooks. He also became the first pediatrician to act as president of the American Association for the Study of Liver Diseases. In his spare time, he coaches youth lacrosse.
A version of this article first appeared on Medscape.com.