Vitamin D boosts HIV-1 resistance in female genital epithelial cells by enhancing antiviral cathelicidin expression.

INTRODUCTION

Elevated levels of serum Vitamin D (VitD) and increased expression of its receptor on peripheral blood cells have been reported in individuals who have been exposed to HIV-1 yet remain seronegative (HESN). This study aimed to investigate the potential antiviral role of VitD in the female genital epithelium, which constitutes the first physical barrier against HIV-1. We hypothesized that VitD may modulate susceptibility to HIV-1 infection by influencing epithelial functions such as tight junction integrity, production of antiviral peptides, and secretion of pro-inflammatory mediators.

METHODS

Endocervical (End1), ectocervical (Ect1) and vaginal (Vk2) epithelial cell lines were cultured in transwells and treated for 24 hours with VitD (1x10-8M). After VitD removal, HIV-1 were added to the apical chamber, and CD4+ T cells (HIV targets) were placed in the basal chamber. HIV-1 transmigration and infection of CD4+ T cells were quantified. CAMP (cathelicidin) transcript levels and protein secretion were also measured.

RESULTS

Pre-treatment of End1, Ect1 and Vk2 epithelial monolayers with VitD reduced HIV-infection of the CD4+ T cells in the basal chamber by 50%, 53%, and 31%, respectively. Only a fraction of the HIV-1 virion applied apically transmigrated across the epithelium. The infectivity of the residual apical HIV-1 virion in the VitD-pre-treated End1, Ect1, and VK2 cultures was reduced by 42%, 36%, and 25%, respectively. These reductions were accompanied by increased RNA transcripts encoding Cathelicidin Antimicrobial Peptide (CAMP) and elevated secretion of CAMP protein into the apical chamber.

CONCLUSION

These findings provide evidence that VitD enhances the antiviral properties of female genital epithelium and reduces HIV-1 infectivity.