Change in serum CXCL10 levels during anti-tuberculosis treatment depends on vitamin D status

Serum levels of the inflammatory C-X-C motif chemokine 10 (CXCL10) are raised in tuberculosis (TB). CXCL10 gene expression is downregulated in monocytes by metabolically active vitamin D-3 (1,25dihydroxy vitamin D). Stratification of patients by serum 25hydroxyvitamin D (25[OH]D) levels at baseline showed that treatment-induced decrease in CXCL10 occurred in those with 'insufficient' and 'deficient' but not in those with 'optimal' levels. In the deficient group, 25(OH)D showed an inverse correlation with CXCL10 levels. CXCL10 may thus be a useful biomarker for the follow-up of response to treatment. However, CXCL10 levels should be interpreted taking into account the baseline serum vitamin D levels of the TB patients.