Deep immune profiling uncovers novel associations with clinical phenotypes of Multisystem Inflammatory Syndrome in Children (MIS-C)

Multisystem Inflammatory Syndrome in Children (MIS-C) is a systemic inflammatory condition that follows SARS-CoV2 infection or exposure in children. Clinical presentations are highly variable and include fever, gastrointestinal (GI) disease, shock, and Kawasaki Disease-like illness (MIS-C/KD). Compared to patients with acute COVID, patients with MIS-C have a distinct immune signature and expansion of TRVB11 expressing T cells. However, the relationship between immunological and clinical phenotypes of MIS-C is unknown. Here, we measured serum biomarkers, TCR repertoire, and SARS-CoV2-specific T cell responses in a cohort of 76 MIS-C patients. Serum biomarkers associated with macrophage and Th1 activation were elevated in patients with shock, consistent with previous reports. Significantly increased SARS-CoV-2-induced IFN-γ, IL-2, and TNF-α production were seen in CD4+ T cells from patients with neurologic involvement and respiratory failure. Diarrhea was associated with a significant reduction in shock-associated serum biomarkers, suggesting a protective effect. TRVB11 usage was highly associated with MIS-C/KD and coronary aneurysms, suggesting a potential biomarker for these manifestations in MIS-C patients. By identifying novel immunologic associations with the different clinical phenotypes of MIS-C, this study provides insights into the clinical heterogeneity of MIS-C. These unique immunophenotypic associations could provide biomarkers to identify patients at risk for severe complications of MIS-C, including shock and MIS-C/KD.

distinct immune signature and expansion of TRVB11 expressing T cells. However, the relationship between immunological and clinical phenotypes of MIS-C is unknown. Here, we measured serum biomarkers, TCR repertoire, and SARS-CoV2-specific T cell responses in a cohort of 76 MIS-C patients. Serum biomarkers associated with macrophage and Th1 activation were elevated in patients with shock, consistent with previous reports. Significantly increased SARS-CoV-2-induced IFN-γ, IL-2, and TNF-α production were seen in CD4 + T cells from patients with neurologic involvement and respiratory failure. Diarrhea was associated with a significant reduction in shock-associated serum biomarkers, suggesting a protective effect. TRVB11 usage was highly associated with MIS-C/KD and coronary aneurysms, suggesting a potential biomarker for these manifestations in MIS-C patients. By identifying novel immunologic associations with the different clinical phenotypes of MIS-C, this study provides insights into the clinical heterogeneity of MIS-C. These unique immunophenotypic associations could provide biomarkers to identify patients at risk for severe complications of MIS-C, including shock and MIS-C/KD.

Research Letter
Multisystem Inflammatory Syndrome in Children (MIS-C) is a systemic inflammatory condition seen in children following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or exposure. Symptoms are highly variable and include fever, diarrhea, cardiogenic shock, respiratory compromise, and Kawasaki Disease (KD)-like features (1,2). Compared with acute Coronavirus Disease 2019 (COVID-19), MIS-C is characterized by distinct immune responses, including increased monocyte/macrophage-derived cytokines such as interleukin (IL) for use under a CC0 license.
This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
We determined clinical associations of MIS-C immunophenotypes in a cohort of 76 MIS-C patients (4). Clinical characteristics of the cohort were previously reported (4) and used to identify patients with diarrhea, cardiac, respiratory, neurologic, and KD-like symptoms (Table S1, S2). Serum biomarkers (n = 69) and T cell receptor (TCR) repertoire (n = 58) were measured as previously reported (4). To quantify SARS-CoV-2-specific T cell responses (n = 24), we stimulated peripheral blood mononuclear cells (PBMCs) with spike, membrane, or nucleocapsid SARS-CoV-2 peptides; cytokine expression was measured using intracellular staining and flow cytometry. Groups were compared using Mann-Whitney with multiple comparison adjustment.
By identifying novel associations with different phenotypes, this study gives insights into potential immunologic mechanisms underlying the clinical heterogeneity of MIS-C. The elevation of serum inflammatory markers -particularly IFN-γ -in patients with severe disease is consistent with findings in other cohorts (2)(3)(4)(5). SARS-CoV-2-specific CD4 + responses in patients with neurological and respiratory involvement suggests that antigen-specific T cell functions may contribute to these symptoms. Conversely, serum biomarker data indicates that diarrhea may protect from severe inflammation in MIS-C, independent of T cell responses. While the GI tract can function as a SARS-CoV-2 antigen reservoir, diarrhea does not always correlate with antigenemia and may portend milder disease in acute COVID-19 (6). Finally, the novel association of MIS-C/KD with expansion of TRVB11-2 -expressing T cells -which is thought to reflect superantigenic responses to spike glycoprotein (7) -suggests a potential link between superantigens and MIS-C/KD, and a possible biomarker for this severe manifestation.
Limitations of this study include variable timing of sample acquisition relative to hospitalization, with samples drawn significantly earlier from patients with shock and neurologic involvement. However, associations with shock were seen in previous studies (2)(3)(4)(5), and other phenotypes were not significantly associated with timing relative to hospitalization. Another potential confounder is that 96% of patients were treated with systemic immunomodulators. Nonetheless, inflammatory responses were still detected because samples were collected during a period of active disease. Strengths include the use of a large multicenter international cohort that improved the generalizability of these results and deep clinical and immunologic profiling that enabled discovery of novel associations. As MIS-C remains a significant complication even in the post-for use under a CC0 license. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted September 2, 2022. ; https://doi.org/10.1101/2022.08.31.22279265 doi: medRxiv preprint vaccine era (1), further investigations should refine biomarkers for severe manifestations, target immunomodulatory treatment, and improve outcomes. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.  This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.