Impact of reproductive aging on the vaginal microbiome and soluble immune mediators in women living with and at-risk for HIV infection

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. Mechanisms mediating risk for HIV acquisition and transmission in menopausal women.

Numbers and corresponding labels indicate potential mechanisms. During menopause there is a loss of epithelial barrier integrity (1) and increase in BV associated species including Atopobium, Prevotella, and Gardnerella (2), which influence release of proinflammatory cytokines e.g. IL-1α, IL-1β and IL-8 (3) promoting recruitment and/or activation of HIV target cells (4) which may increase risk for HIV acquisition and for HIV positive women increase HIV replication (5) and subsequent viral shedding (6). Loss of H202 producing protective lactobacillus species Lactobacillus (L.) crispatus, L jensenii, L. gasseri (7) and decreased protective immune mediators (human beta defensins, SLPI) (8) may also increase risk for HIV acquisition during menopause. In menopausal women with HIV, E. coli antibacterial activity is lower, reflecting a Lactobacillus deficient microbiome and HSV inhibitory activity is higher reflective of inflammation.

Fig 2. HIV+ postmenopausal participants have significantly lower CVL E. coli and higher HSV inhibitory activity.

CVL E. coli (A), HSV (B) and HIV inhibitory activity (C) in premenopausal and postmenopausal HIV negative and HIV positive participants. The lines represent the median with interquartile range for percent inhibition of E. coli colonies (A) percent inhibition of HSV plaques (B) and percent reduction in relative luciferase units compared with control (C). Comparisons were made between all pairwise groups, only those with p values ≤ 0.05 and those comparing pre and postmenopausal participants are reported. Circle indicates HIV enhancing activity in HIV+ participants on ART.

Fig 3. Differences in the taxonomic composition of the vaginal microbiome by reproductive status and levels of E. coli and HIV inhibitory activity.

Taxonomic composition of the vaginal microbiome by reproductive status for HIV+ (A) and HIV- (B) participants, by levels of CVL E. coli bactericidal activity for HIV+ (C) and HIV- (D) participants and by levels of CVL HIV inhibitory activity for HIV+ (E) and HIV- (F) participants. Proportion of genera contributing >1% shown. Asterisks (*) indicate taxa with significantly different relative abundances between groups as determined by an LDA score ≥2. Low and high E. coli and HIV inhibition correspond to the bottom and top quartiles.