Background: Defensins are natural endogenous antimicrobial peptides with potent anti-HIV activity and immuno-modulatory effects. We recently demonstrated that immature dendritic cells (DC) produce alpha-defensins1-3 and that alpha-defensins1-3 modulate DC generation and maturation. Since DC-HIV interaction plays a critical role during the first steps of HIV infection, we investigated the possible impact of alpha-defensins1-3 production by DC on disease progression.
Methodology/principal findings: Monocyte-derived DC (MDDC) were analyzed comparatively in healthy controls (HC) and HIV-infected patients, including untreated "elite" and "viremic" controllers, untreated viremic non-controllers and antiretroviral-treated patients. We found that production of alpha-defensins1-3 was significantly increased in MDDC from HIV-infected patients versus HC, and this increase was mainly due to that observed in controllers, while in non-controllers the increase was not statistically significant (controllers vs. HC, p<0.005; controllers vs. non-controllers p<0.05). Secreted alpha-defensins1-3 by immature MDDC positively correlated with CD4 T cell counts in controllers, but not in non-controllers. Moreover, independently of their clinical classification, HIV-infected patients with higher alpha-defensins1-3 secretion by immature MDDC showed slower disease progression, measured as no decrease in the number of CD4+ T-cells below 350 cell/mm(3), lower increase of plasma viral load and no initiation of treatment over time. Plasma alpha-defensins1-3 levels lacked any relationship with immunologic and virologic parameters.
Conclusions/significance: High production of alpha-defensins1-3 by immature DCs appears as a host protective factor against progression of HIV-1 infection, suggesting potential diagnostic, therapeutic and preventive implications. This protective effect may arise from the activity of alpha-defensins1-3 to damage the virions prior and/or after their internalization by immature DC, and hence favoring a more efficient viral processing and presentation to HIV-specific CD4+ T cells, without or with a minor rate of transmission of infectious HIV-1 virions.