A recent study suggests that Multisystem Inflammatory Syndrome in Children (MIS-C) is triggered by gastrointestinal breach of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral particles from the gut lumen into systemic circulation. The virus remains in the gut weeks to months after respiratory infection, causing zonulin release from the intestinal epithelial cells. Zonulin loosens tight junctions, permitting trafficking of highly inflammatory viral particles into circulation. Current MIS-C treatments target the subsequent immune hyperactivation, not the causative loss of mucosal barrier integrity. Larazotide, a zonulin inhibitor, prevents breakdown of tight junctions, limiting antigen trafficking.
Children with MIS-C were treated with larazotide as an adjuvant to steroid/intravenous immunoglobulin therapy. Clinical outcomes, SARS-CoV-2 antigenemia, and cytokine profiles are reported. Outcomes were compared with children with MIS-C receiving steroids and/or IVIG therapy alone.
Four children with MIS-C, ages 3-17 years, were enrolled.
Patients were treated with open label larazotide 10 mcg/kg (maximum 500 mcg/dose) orally four times daily for 21 days.
All four patients tolerated larazotide without adverse effects and displayed reduction in Spike antigenemia to undetectable levels. When compared with 22 children with MIS-C receiving steroids and/or intravenous immunoglobulin therapy alone, larazotide-treated patients reported significantly improved time to resolution of gastrointestinal symptoms (p = 0.03), and time to clearance of Spike antigenemia (p = 0.04), plus a trend towards shorter length of stay.
Larazotide appears safe and well-tolerated and may offer potential benefit as an adjuvant to immune-targeted therapies. Expansion of clinical trials is urgently needed to ascertain the clinical impact of larazotide on MIS-C.
Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.

The SARS-CoV-2 outbreak and subsequent COVID-19 pandemic have highlighted the urgent need to determine what cells are susceptible to infection and for assays to detect and quantify SARS-CoV-2. Furthermore, the ongoing efforts for vaccine development have necessitated the development of rapid, high-throughput methods of quantifying infectious SARS-CoV-2, as well as the ability to screen human polyclonal sera samples for neutralizing antibodies against SARS-CoV-2. To this end, our lab has adapted focus forming assays for SARS-CoV-2 using Vero CCL-81 cells, referred to in this text as Vero WHO. Using the focus forming assay as the basis for screening cell susceptibility and to develop a focus reduction neutralization test. We have shown that this assay is a sensitive tool for determining SARS-CoV-2 neutralizing antibody titer in human, non-human primate, and mouse polyclonal sera following SARS-CoV-2 exposure. Additionally, we describe the viral growth kinetics of SARS-CoV-2 in a variety of different immortalized cell lines and demonstrate via human ACE2 and viral spike protein expression that these cell lines can support viral entry and replication.