Effect of 1,25-dihydroxy vitamin D3 on toll-like receptor gene expression in neutrophils of pulmonary tuberculosis

We studied the effect of 1,25-dihydroxy vitamin D-3 [1,25(OH)(2)D-3] on toll-like receptor (TLR) gene expression in neutrophils cultured with Mycobacterium tuberculosis (Mtb) with or without 1,25(OH)(2)D-3 in pulmonary tuberculosis patients and healthy controls. 1,25(OH)(2)D-3 significantly increased the expression of TLR2, TLR9 and TIRAP genes compared to control cells in both the study groups (P < 0.05). In healthy controls, a significantly upregulated expression of TIRAP was observed in Mtb infected cells cultured with 1,25(OH)(2)D-3 compared to Mtb infected cells alone (P < 0.05). In conclusion, 1,25(OH)(2)D-3 upregulated the expression of TLR and TIRAP genes, which could lead to the activation of TLR signalling pathways and augment the innate immunity to tuberculosis.