Previous mouse and clinical studies demonstrate a link between Th2 intestinal inflammation and induction of the effector phase of food allergy. However, the mechanism by which sensitization and mast cell responses occurs is largely unknown. We demonstrate that interleukin (IL)-9 has an important role in this process. IL-9–deficient mice fail to develop experimental oral antigen–induced intestinal anaphylaxis, and intestinal IL-9 overexpression induces an intestinal anaphylaxis phenotype (intestinal mastocytosis, intestinal permeability, and intravascular leakage). In addition, intestinal IL-9 overexpression predisposes to oral antigen sensitization, which requires mast cells and increased intestinal permeability. These observations demonstrate a central role for IL-9 and mast cells in experimental intestinal permeability in oral antigen sensitization and suggest that IL-9–mediated mast cell responses have an important role in food allergy.

*Clinical studies have demonstrated a link between the eosinophil-selective chemokines, eotaxins (eotaxin-1/CCL11 and eotaxin-2/CCL24), eosinophils, and the inflammatory bowel diseases, Crohn's disease and ulcerative colitis (UC). However, the cellular source and individual contribution of the eotaxins to colonic eosinophilic accumulation in inflammatory bowel diseases remain unclear. In this study we demonstrate, by gene array and quantitative PCR, elevated levels of eotaxin-1 mRNA in the rectosigmoid colon of pediatric UC patients. We show that elevated levels of eotaxin-1 mRNA positively correlated with rectosigmoid eosinophil numbers. Further, colonic eosinophils appeared to be degranulating, and the levels positively correlated with disease severity. Using the dextran sodium sulfate (DSS)-induced intestinal epithelial injury model, we show that DSS treatment of mice strongly induced colonic eotaxin-1 and eotaxin-2 expression and eosinophil levels. Analysis of eosinophil-deficient mice defined an effector role for eosinophils in disease pathology. DSS treatment of eotaxin-2 ؊/؊ and eotaxin-1/2 ؊/؊ mice demonstrated that eosinophil recruitment was dependent on eotaxin-1. In situ and immunofluorescence analysis-identified eotaxin-1 expression was restricted to intestinal F4/80 ؉ CD11b ؉ macrophages in DSS-induced epithelial injury and to CD68 ؉ intestinal macrophages and the basolateral compartment of intestinal epithelial cells in pediatric UC. These data demonstrate that intestinal macrophage and epithelial cell-derived eotaxin-1 plays a critical role in the regulation of eosinophil recruitment in colonic eosinophilic disease such as pediatric UC and provides a basis for targeting the eosinophil/eotaxin-1 axis in UC.

The SARS‐CoV‐2 pandemic continues to place a substantial burden on healthcare systems. Outpatient therapies for mild‐to‐moderate disease have reduced hospitalizations and deaths in clinical trials, but the real‐world effectiveness of monoclonal antibodies and oral antiviral agents in solid organ transplant recipients (SOTR) with coronavirus disease‐2019 (COVID‐19) is largely uncharacterized. We conducted a single‐center, retrospective review of 122 SOTR diagnosed with COVID‐19 in the outpatient setting during the Omicron surge to address this knowledge gap. The mean age was 54 years, 57% were males, and 67% were kidney transplant recipients. The mean time from transplant to COVID‐19 diagnosis was 75 months. Forty‐nine (40%) received molnupiravir, 24 (20%) received sotrovimab, and 1 (0.8%) received nirmatrelvir/ritonavir. No outpatient therapy was administered in 48 (39%). All 122 SOTR had >30 days follow‐up. Rates of hospitalization within 30 days of initiating therapy for molnupiravir, nirmatrelvir/ritonavir, and sotrovimab were 16% (8/49), 0% (0/1), and 8% (2/24), respectively, compared to 27% (13/48) in patients without outpatient therapy. There were no deaths in those who received any therapy versus 3 (6%) deaths in patients without outpatient therapy ( p = .002). Overall, our experience suggests a role for monoclonal antibodies and oral antiviral agents in reducing COVID‐19‐related morbidity and mortality in SOTR.

Our survey emphasizes the high rate of pregnancy-related listeriosis in Israel and shows that specific clones might account for this.