Fig. 1.

The crucial role of vitamin D in the immunopathogenesis of TB. Vitamin D has immunomodulatory effects on the immune-system, so that it suppresses Th1, Th17, B cell as well as DCs maturation. However, it also stimulates the proliferation of T regulatory (T reg) cells, which in turn inhibit the excessive T cell-mediated immunity and tissue damage. In the other hand, it also has a specific receptor on the macrophages, vitamin D receptor (VDR). After the binding to the VDR, vitamin D triggers the processes such as the production of natural human antimicrobial peptides (AMPs), nitric oxide synthesis and chemotaxis to provoke immune response for clearance of M. tuberculosis (Mtb).