Impact of Vitamin D in Prophylaxis and Treatment in Tuberculosis Patients

Abstract

Vitamin D plays a crucial role in many infectious diseases, such as tuberculosis (TB), that remains one of the world's top infectious killers with 1.5 million deaths from TB in 2021. Vitamin D suppresses the replication of Mycobacterium tuberculosis in vitro and showed a promising role in TB management as a result of its connection with oxidative balance. Our review encourages the possible in vivo benefit of a joint administration with other vitamins, such as vitamin A, which share a known antimycobacterial action with vitamin D. However, considering the low incidence of side effects even at high dosages and its low cost, it would be advisable to assess vitamin D level both in patients with active TB and high-risk groups and administer it, at least to reach sufficiency levels.

Keywords: TB; outcome; prophylaxis; treatment; tuberculosis; vitamin D.

Figure 1

Metabolism and action of Vitamin D in MT infection. Vitamin D is synthesized in the skin following stimulation by UV rays or introduced with food. In the blood, vitamin D circulates free or bound to VDBP, reaches the liver, where it is converted to 25-(OH)-vit. D by the enzyme hydroxylase. Reintroduced into the bloodstream, it reaches the kidney, where it is further hydroxylated; this active form has multiple activities on different organs (parathyroid, bones, pancreas, intestine). Part of the 25-(OH)-vit. D enters the macrophages, where by hydroxylation it is activated, binds the VDR, passes into the nucleus and increases the transcription of genes for hCAP18. This, cleaved, produces LL-37, which has anti-MT activity, increases autophagy and macrophage killing. In addition, 25(OH)D modulates the innate and adaptive immune system and increases in cytokines (IL-4, IL-5), and INF-γ increases in the antibody-mediated response.