Background: Mucosal surfaces of the female reproductive tract are the main routes of heterosexual transmission of human immunodeficiency virus type 1 (HIV-1), but the contribution of each of the reproductive sites to mucosal transmission is unknown.
Methods: We compared levels of HIV-1 transcription between ectocervical and endometrial tissue explants infected ex vivo with HIV-1.
Results: We detected higher levels of HIV-1 transcription in the ectocervix. Although CD45 expression was also increased at this site, higher levels of HIV-1 transcription could not be accounted for exclusively by differences in CD45 expression. This suggests that factors other than CD45 levels regulate HIV-1 transcription within the ectocervix. We detected higher levels of interleukin (IL)-6 at this site. Furthermore, addition of recombinant IL-6 to tissue explants enhanced HIV-1 transcription to a much greater degree in the ectocervix than in the endometrium.
Conclusions: This is, to our knowledge, the first study to compare ectocervix and endometrium in a tissue explant model of HIV-1 infection and to demonstrate greater HIV-1 transcription in the ectocervix. Our results suggest that the ectocervix is more conducive to HIV-1 replication than is the endometrium and that IL-6 enhances HIV-1 transcription at this site. Thus, the ectocervix is an important site to be considered in heterosexual transmission of HIV-1.