Frequency and Functional Impact of the c.32A>T Genetic Polymorphism of TLR7 in Women Infected With HIV-1 : the ANRS EP53 Study

Plasmacytoid dendritic cells (pDCs) are key actors of innate immunity that produce high levels of interferon (IFN)-alpha after activation of their Toll-Like Receptors (TLR) by pathogens. A difference between men and women has recently been shown in the level of IFN-alpha produced by pDCs after TLR activation. The production of IFN-alpha in response to TLR7 activation is higher in the presence of estrogens. This could be responsible for gender differences in the level of plasma HIV-1 RNA, that is lower in female as compared to male by about 50%, and for the sex-based differences in the susceptibility to HIV infection. Besides the role of estrogens, X-linked genetic factors could also be involved in the sex-dependent differences in the TLR7-mediated responses of pDCs. TLR7 gene is located on the X chromosome. A single nucleotide polymorphism (SNP) of the TLR7 gene, c.32A>T, have been associated with accelerated disease progression in male HIV patients, and was found over represented in female HIV as well as HCV patients, suggesting that the T allele is associated with a gender-dependent increase of susceptibility to RNA virus infections. A peripheral blood sample will be collected from HIV-infected women and healthy control to measure TLR-7 SNP frequency by PCR. IFN-alpha production from pDCs after HIV-1 RNA sensing by TLR7 will also be assessed.