Micro RNA-19a suppresses thrombospondin-1 in CD35⁺ B cells in the intestine of mice with food allergy

Disruption of immune tolerance is associated in the pathogenesis of allergy. Thrombospondin-1 (TSP1) plays a role in the maintenance of immune tolerance, which is compromised in allergic disorders. Micro RNA (miR) is involved in the regulation of immune responses. This study tests a hypothesis that miR-17-92 cluster is involved in the regulation of TSP1 in the intestinal CD35⁺ B cells. In this study, a food allergy mouse model was developed. The intestinal B cells were isolated to be analyzed for the expression of a miR-17-92 cluster and TSP1. The role of miR-19a in the suppression of TSP1 in B cells was tested in a cell culture model. We observed that the levels of TSP1 were significantly decreased; the levels of miR-19a were significantly increased in intestinal CD35⁺ B cells of mice sensitized to ovalbumin (OVA) as compared with naïve controls. Exposure to interleukin (IL)-4 suppressed the expression of TSP1 in B cells, which was abolished by inhibition of miR-19a. miR-19a mediated the effects of IL-4 on repressing TSP1 expression in B cells. We conclude that IL-4 suppresses the expression of TSP1 in the intestinal CD35⁺ B cells via up regulating miR-19a. The miR-19a may be a target to regulate the immune tolerant status in the body.