Date Published: April 26, 2019
Publisher: Public Library of Science
Author(s): Kerry Murphy, Marla J. Keller, Kathryn Anastos, Shada Sinclair, J. Cooper Devlin, Qiuhu Shi, Donald R. Hoover, Brian Starkman, Jamie McGillick, Caroline Mullis, Howard Minkoff, Maria Gloria Dominguez-Bello, Betsy C. Herold, Alan Landay.
Reproductive aging may impact the vaginal microbiome and genital tract mucosal immune environment and contribute to genital tract health in women living with and at-risk for HIV infection.
A cross-sectional study of 102 HIV+ (51 premenopausal, 51 postmenopausal) and 39 HIV-uninfected (HIV-) (20 premenopausal, 19 postmenopausal) women was performed in Bronx and Brooklyn, NY. Cervicovaginal lavage (CVL) was collected for quantification of innate antimicrobial activity against E. coli, HSV-2 and HIV and immune mediators by Luminex and ELISA. Microbiome studies by qPCR and 16S rRNA sequencing were performed on vaginal swabs.
HIV+ postmenopausal compared to premenopausal participants had lower median E. coli bactericidal activity (41% vs. 62%, p = 0.001), lower median gene copies of Lactobacillus crispatus (p = 0.005) and Lactobacillus iners (p = 0.019), lower proportions of Lactobacillus iners, higher proportions of Gardnerella and Atopobium vaginae and lower levels of human beta defensins (HBD-2, HBD-3) and secretory leukocyte protease inhibitor (SLPI), p<0.001. HSV-2 inhibitory activity was higher in HIV+ postmenopausal compared to premenopausal participants (37% vs. 17%, p = 0.001) and correlated with the proinflammatory molecules interleukin (IL) 6, IL-8, human neutrophil peptide (HNP) 1–3, lactoferrin and fibronectin. Similar trends were observed in HIV- postmenopausal compared to premenopausal participants. HIV inhibitory activity did not differ by reproductive status in the HIV+ participants but was significantly higher in HIV- postmenopausal compared to premenopausal participants and in participants with suppressed plasma viral load, and inversely correlated with gene copies of G. vaginalis and BVAB2. A significant proportion of HIV+ participants on ART exhibited HIV enhancing activity. HIV+ postmenopausal compared to premenopausal participants have less CVL E. coli bactericidal activity, reflecting a reduction in Lactobacilli and a greater proportion of Gardnerella and A. vaginae, and more HSV-2 inhibitory activity, reflecting increased mucosal inflammation. The effect of menopause on mucosal immunity was greater in HIV+ participants, suggesting a synergistic impact. Promotion of a lactobacillus dominant vaginal microbiome and reduced mucosal inflammation may improve vaginal health and reduce risk for shedding of HIV and potential for HIV transmission in HIV+ menopausal women.
Menopause may be a time of reduced genital tract health reflecting changes in the vaginal microbiome and mucosal environment. Previous studies in HIV uninfected (HIV-) women have demonstrated a reduction in lactobacilli with an increase in diverse anaerobes in postmenopausal compared to premenopausal women.[1, 2] Changes in immune cell phenotype and function, disruption of epithelial integrity, reduction in protective immune mediators and increased expression of pro-inflammatory genes have also been described.[1–5] Together, these changes may increase the risk of acquiring HIV and, in HIV-infected (HIV+) women, promote viral shedding and transmission (Fig 1).[6–10] Among incident US HIV infections in 2015, 17% occurred in persons >50 years of age and approximately 45% of people living with HIV in the US are aged ≥50, [11, 12] underscoring the importance of studying the impact of menopause on the cervicovaginal mucosal environment and its link to HIV acquisition and transmission.
The prevalence of HIV in postmenopausal women continues to increase as the life expectancy of HIV+ and HIV- women converge. Thus, it is important to characterize the cervicovaginal mucosal immune environment and vaginal microbiota in postmenopausal women as the two are likely linked and contribute to genital tract health as well as risk for HIV acquisition and transmission. The salient findings of this study are that HIV+ postmenopausal women have less CVL E. coli bactericidal activity, reflecting a lower proportion of lactobacilli species and a greater proportion of Gardnerella and A. vaginae and more HSV-2 inhibitory activity reflecting increased levels of inflammatory mediators compared to HIV+ premenopausal women. There is a wide distribution of vaginal Community State Types (CST) which has been described in detail for reproductive aged women  including those dominant in protective lactobacilli (L. crispatus, L. gasserii, or L. jensenii) (CST I, II or V) as well as those dominated by L. iners or diverse anaerobes (e.g. CST III or IV). CST IV species appear to be more prevalent in women who identify as Black or Hispanic suggesting race/ethnicity may be a factor mediating some of the variability in the vaginal microbiome of individual women [38–40]. Studies of postmenopausal women have also demonstrated marked variability in CST, with higher proportions of CST-IV species in women with vaginal dryness and/or atrophy.[1, 2] We did not collect data on symptoms of vaginal dryness or atrophy therefore we were unable to assess for this. Given the large proportion of study participants (55–67%) who reported their race as Black, it is reasonable to postulate that race may be one factor in a complex network of interactions mediating the vaginal microbiome in postmenopausal participants despite the lack of differences in alpha and beta diversity by self-reported race in this study (S4 Fig). The reduction in lactobacilli and concomitant increase in dysbiosis and inflammation that occur in the setting of menopause and HIV infection may merge to influence risk for genital tract HIV shedding and subsequent transmission (Fig 1).[41–44] The effect of menopause on mucosal immunity was greater in HIV+ compared to HIV- participants, suggesting a synergistic relationship likely reflecting the contribution of chronic immune activation that occurs with both aging and HIV infection.[21, 23, 45]