Vitamin D resolved human and experimental asthma via B lymphocyte-induced maturation protein 1 in T cells and innate lymphoid cells.

Background: Vitamin D (VitD) is known to have immunomodulatory functions, and VitD deficiency is associated with more severe asthma.

Objective: We aimed to assess the immunoregulatory effects of VitD food supplementation on asthma manifestation, with particular focus on T cells and type 2 innate lymphoid cells.

Methods: Preschool children and adult asthmatic cohorts were analyzed in the context of VitD supplementation and serum levels. In a murine model of ovalbumin-induced asthma, effects of diet VitD sufficiency and deficiency on T cells and type 2 innate lymphoid cells immune mechanisms were investigated.

Results: We found less severe and better-controlled asthma phenotypes along with reduced need for steroid medication in preschool children and asthmatic adults with VitD supplementation. VitD serum levels correlated with B lymphocyte-induced maturation protein 1 (Blimp-1) expression in blood peripheral mononuclear cells. VitD-supplement-fed mice showed decreased asthmatic traits, with a decrease in IgE serum levels, reduced airway mucus, and increased IL-10 production by lung cells. Furthermore, we discovered an upregulation of effector T cells and Blimp-1 lung tissue-resident memory T cells as well as induction of anti-inflammatory Blimp-1 lung innate lymphoid cells producing IL-10.

Conclusion: Supplementing VitD resulted in amelioration of clinical asthma manifestations in human studies as well as in experimental allergic asthma, indicating that VitD shifts proinflammatory immune responses to anti-inflammatory immune responses via upregulating Blimp-1 in lung innate lymphoid cells and tissue-resident memory cells.