Food-sensitized pediatric patients show colonic cow's milk protein-specific Th2 cells.

Food allergies have become a health concern worldwide. Around 6% to 10% of children are allergic to cow's milk proteins. We have previously characterized colorectal polyps in patients sensitized to food allergens. These polyps are classified as inflammatory and present a type 2 environment, with elevated interleukin (IL)-13 and IL-4, and are a site of immunoglobulin E synthesis. In this study, we characterized and isolated cow's milk protein-specific T cell lines and T cell clones from the lamina propria of polyps from patients sensitized to these proteins. Isolated T cells responded to cow's milk proteins similarly to peripheral blood T cells, showing antigen-specific cell proliferation and Th2 cytokines release in vitro. T cell clones obtained were all CD4+ T cells and expressed the membrane TCRαß receptor and secreted higher IL-4, IL-5, and IL-13 amounts than unstimulated cells, whereas interferon γ secretion remained unchanged. Remarkably, the gut homing chemokine receptor CCR9 was augmented in cow's milk-specific peripheral and lamina propria T cells, and CCL25 was found to be expressed in the inflammatory polyp tissue and not in the adjacent mucosa. In conclusion, we isolated and characterized cow's milk-specific lamina propria CD4+ Th2 cells from colonic inflammatory polyps. CCR9 expression on these cells, along with increase secretion of CCL25 in the polyp, favors recruitment and cow's milk-specific allergic response within the inflammatory polyp tissue. Our findings may be critical to understand the underlying mechanism that promotes immunoglobulin E synthesis in the colon of cow's milk proteins allergic patients, contributing to the development of novel T cell-targeted immunotherapies.

Probiotic Lactobacilli Isolated from Kefir Promote Down-Regulation of Inflammatory Lamina Propria T Cells from Patients with Active IBD.

Ulcerative colitis and Crohn's disease, the two main forms of inflammatory bowel disease (IBD), are immunologically mediated disorders. Several therapies are focused on activated T cells as key targets. Although Lactobacillus kefiri has shown anti-inflammatory effects in animal models, few studies were done using human mucosal T cells. The aim of this work was to investigate the immunomodulatory effects of this bacterium on intestinal T cells from patients with active IBD. Mucosal biopsies and surgical samples from IBD adult patients (n = 19) or healthy donors (HC; n = 5) were used. Lamina propria mononuclear cells were isolated by enzymatic tissue digestion, and entero-adhesive Escherichia coli-specific lamina propria T cells (LPTC) were expanded. The immunomodulatory properties of L. kefiri CIDCA 8348 strain were evaluated on biopsies and on anti-CD3/CD28-activated LPTC. Secreted cytokines were quantified by ELISA, and cell proliferation and viability were assessed by flow cytometry. We found that L. kefiri reduced spontaneous release of IL-6 and IL-8 from inflamed biopsies ex vivo. Activated LPTC from IBD patients showed low proliferative rates and reduced secretion of TNF-α, IL-6, IFN-γ and IL-13 in the presence of L. kefiri. In addition, L. kefiri induced an increased frequency of CD4+FOXP3+ LPTC along with high levels of IL-10. This is the first report showing an immunomodulatory effect of L. kefiri CIDCA 8348 on human intestinal cells from IBD patients. Understanding the mechanisms of interaction between probiotics and immune mucosal cells may open new avenues for treatment and prevention of IBD.