Increase in HIV receptors/co-receptors/alpha-defensins in inflamed human gingiva

Transmission of HIV-1 through the oral cavity is considered to be a rare event. To identify factors in resistance/susceptibility to oral HIV-1 infection, we analyzed expression in human gingiva of HIV-1 receptors Langerin, DC-SIGN, MR, and GalCer, HIV-1 co-receptors CCCR5, CXCR4, and anti-microbial protein alpha-defensin-1. Our results show that healthy gingiva is infiltrated with cells expressing all HIV-1 receptors tested; however, there are very few CCR5(+) cells and a complete absence of CXCR4(+) cells in the lamina propria. In chronic periodontitis (CP), DC-SIGN, MR, CXCR4, and CCR5 increase, but this was accompanied by a ten-fold increase in alpha-defensin-1 mRNA. The CCR5(+) cells were revealed to be T-cells, macrophages, and dermal dendritic cells. Moreover, epithelial expression of GalCer and CXCR4 together was not apical and showed no trend with underlying inflammation. Thus, low expression of HIV-1 co-receptors in health and high expression of alpha-defensin during CP may comprise endogenous factors that provide protection from oral HIV-1 infection.