Vitamin D May Prevent Allergies, Asthma

PITTSBURGH, Pa.Data from a study published in the Journal of Clinical Investigation provided rationale for a therapeutic trial of vitamin D to prevent or treat allergic Bronchopulmonary aspergillosis (ABPA)  in patients with cystic fibrosis (Aug. 16, 2020).  ABPA is caused by a dominant Th2 immune response to antigens derived from the opportunistic mold Aspergillus, most commonly Aspergillus fumigatus. It occurs in 4 percent to 15 percent of patients with cystic fibrosis (CF). Researchers compared cohorts of A. fumigates-colonized CF patients with and without ABPA to identify factors mediating tolerance versus sensitization.

The costimulatory molecule OX40 ligand (OX40L) was critical in driving Th2 responses to A. fumigatus in peripheral CD4+ T cells isolated from patients with ABPA. In contrast, CD4+ T cells from the non-ABPA cohort did not mount enhanced Th2 responses in vitro and contained a higher frequency of TGF-betaexpressing regulatory T cells. Heightened Th2 reactivity in the ABPA cohort correlated with lower mean serum vitamin D levels. In vitro addition of 1,25 OH-vitamin D3 substantially reduced DC expression of OX40L and increased DC expression of TGF-beta. This in vitro treatment also resulted in increased Treg TGF-beta expression and reduced Th2 responses by CD4+ T cells from patients with ABPA.