Reduced vitamin D receptor (VDR) and cathelicidin antimicrobial peptide (CAMP) gene expression contribute to the maintenance of inflammatory immune response in leprosy patients.

Leprosy is an infectious disease influenced by genetic, immunological, and environmental factors. Reduced gene expressions may be associated with the immunological response pattern and leprosy susceptibility. We investigated the direct and indirect effects of Vitamin D Receptor (VDR) and Cathelicidin Antimicrobial Peptide (CAMP) gene expressions on the serum levels of vitamin D, Cathelicidin, and cytokines in newly-diagnosed leprosy patients and post-six-months of multidrug therapy (MDT). Thirty-four leprosy patients were assessed, paucibacillary (PB; n = 14) and multibacillary (MB; n = 20) cases, untreated or having received six months of MDT, 18 healthy controls, and 25 household contacts. VDR and CAMP gene expression levels were strongly correlated to some important cytokines in both, untreated leprosy patients (PB, r = 0.9319; MB, r = 0.9569) and patients who had undergone MDT (PB, r = 0.9667; MB, r = 0.9569). We observed that both gene expressions directly influenced IL-2, IFN-γ, and IL-17F serum levels in leprosy patients compared to the household contacts and healthy individuals. VDR and CAMP gene expressions induced a persistent inflammatory response in PB and MB leprosy patients, even after six months of MDT, to fight the Mycobacterium leprae infection. Due to the persistent inflammatory profile, multidrug therapy is suggested to be maintained for more than six months, especially for MB patients. Vitamin D supplementation is recommended from the onset as a transcription factor to improve VDR and CAMP gene expression in leprosy patients.