Tuberculosis:
The first treatment of skin tuberculosis was discovered by lamp arc radiation and the inventor Neils Rayberg Finsen (1890-1904) was awarded by Noble prize for this discovery (94). It is suggested that UV radiation from lamp arc produces vitamin D in the body and facilitates the production of anti-microbial peptides such as cathelicidin to fight against infectious diseases including tuberculosis (95, 96, 97). Many observational studies showed strong association of vitamin D deficiency with tuberculosis in different populations including Pakistani population (98, 99, 100).
Some of the case control studies found severe vitamin D deficiency in patients with pulmonary and extra pulmonary tuberculosis (98, 101, 102, 103, 104, 105, 106, 107). A case control study designed to evaluate the amount of vitamin D, anti-microbial peptide cathelicidin, chemerin and inflammatory marker TNF α in pulmonary tuberculosis and healthy subjects found significant association was present between vitamin D, cathelicidin, chemerin and TNF α. (108).
An interventional trial named as SUCCINIT study (Supplementary cholecalciferol in recovery from tuberculosis) was conducted in patients with pulmonary tuberculosis to evaluate the effects of vitamin D supplementation (109). A total of 259 patients with newly diagnosed TB were randomly divided into two groups (Vitamin D group n=132 and placebo group n=129). The vitamin D group was administered by 600000 IU of vitamin D on weekly basis for two weeks along with standard medications while, placebo group was administered by normal saline along with standard medications. The results of this study showed improvement in clinical, radiological and host defense outcomes in the patients of vitamin D group.
Another interventional trial was conducted to evaluate adjuvant effects of vitamin D with anti-tuberculosis therapy (ATT) as compared with ATT alone for 77 days (110). The results showed improvement in some parameters such as increase in serum vitamin D, calcium, BMI and hemoglobin and decrease in erythrocytes sedimentation rate (ESR), C-reactive proteins (CRP), total white blood count and a 12 days earlier sputum conversion as compared with placebo group.
A similar study also showed early sputum conversion in smear positive pulmonary tuberculosis by the administration of vitamin D (100000 IU) on every fourteenth day for three months (111). The results showed improvement in the vitamin D levels and rate of sputum smear conversion in patients with pulmonary tuberculosis.
CXCL10 is a chemo-attractant factor that is found to be elevated in TB patients (112). Vitamin D levels were found negatively associated with the CXCL10 levels in 119 TB patients in Karachi (113).