Brett Shannon

Impact of Asymptomatic Herpes Simplex Virus Type 2 Infection on Mucosal Homing and Immune Cell Subsets in the Blood and Female Genital Tract

HSV-2 infection is common and generally asymptomatic, but it is associated with increased HIV susceptibility and disease progression. This may relate to herpes-mediated changes in genital and systemic immunology. Cervical cytobrushes and blood were collected from HIV-uninfected African/Caribbean women in Toronto, and immune cell subsets were enumerated blindly by flow cytometry. Immune differences between groups were assessed by univariate analysis and confirmed using a multivariate model. Study participants consisted of 46 women, of whom 54% were infected with HSV-2. T cell activation and expression of the mucosal homing integrin α4β7 (19.60 versus 8.76%; p < 0.001) were increased in the blood of HSV-2–infected women. Furthermore, expression of α4β7 on blood T cells correlated with increased numbers of activated (coexpressing CD38/HLA-DR; p = 0.004) and CCR5+ (p = 0.005) cervical CD4+ T cells. HSV-2–infected women exhibited an increase in the number of cervical CD4+ T cells (715 versus 262 cells/cytobrush; p = 0.016), as well as an increase in the number and proportion of cervical CD4+ T cells that expressed CCR5+ (406 versus 131 cells, p = 0.001; and 50.70 versus 34.90%, p = 0.004) and were activated (112 versus 13 cells, p < 0.001; and 9.84 versus 4.86%, p = 0.009). Mannose receptor expression also was increased on cervical dendritic cell subsets. In conclusion, asymptomatic HSV-2 infection was associated with significant systemic and genital immune changes, including increased immune activation and systemic α4β7 expression; correlation of the latter with highly HIV-susceptible CD4+ T cell subsets in the cervix may provide a mechanism for the increased HIV susceptibility observed in asymptomatic HSV-2–infected women.

Genital immunology and HIV susceptibility in young women

Women account for a substantial majority of HIV infections in endemic regions, where women are also infected at a much younger age than men. Part of this epidemiological skewing is due to socio‐cultural factors, but it is clear that biological factors enhance the susceptibility of women – particularly young women – to HIV acquisition after sexual exposure. These factors, including important differences in mucosal immunology at the site of genital HIV exposure, are the focus of this concise review. Compared to heterosexual men, women have an increased surface area of mucosal HIV exposure, increased mucosal expression of the HIV co‐receptor CCR5 and a greater probability of virus exposure on the rectal mucosa. Differences that are specific to young women include a pro‐inflammatory immune environment and a proportionate increase in single‐cell, columnar genital epithelium. These important biological reasons for enhanced HIV susceptibility in young women highlight the need for targeted HIV prevention within this vulnerable population.

A Randomized Controlled Pilot Trial of Valacyclovir for Attenuating Inflammation and Immune Activation in HIV/Herpes Simplex Virus 2–Coinfected Adults on Suppressive Antiretroviral Therapy

BACKGROUND Human immunodeficiency virus (HIV) is associated with increased systemic inflammation and immune activation that persist despite suppressive antiretroviral therapy (ART). Herpes simplex virus type 2 (HSV-2) is a common coinfection that may contribute to this inflammation. METHODS Sixty HIV type 1 (HIV-1)/HSV-2-coinfected adults on suppressive ART were randomized 1:1:1 to 12 weeks of placebo, low-dose valacyclovir (500 mg twice daily), or high-dose valacyclovir (1 g twice daily) in this 18-week trial. Co-primary outcome measures were the percentage of activated (CD38(+)HLA-DR(+)) CD8 T cells in blood, and highly sensitive C-reactive protein, interleukin 6, and soluble intercellular adhesion molecule 1 in plasma. Secondary outcomes included additional immune, inflammatory cytokine, and endothelial activation markers. The impact of valacyclovir (both groups combined) on each outcome was estimated using treatment × time interaction terms in generalized estimating equation regression models. RESULTS Participants were mostly white (75%) men who have sex with men (80%). Median age was 51 (interquartile range [IQR], 47-56) years, median duration of HIV infection was 15 (IQR, 8-21) years, median CD4 count at enrollment was 520 (IQR, 392-719) cells/µL, and median nadir CD4 count was 142 (IQR, 42-240) cells/µL. Valacyclovir was not associated with significant changes in any primary or secondary immunological outcomes in bivariate or multivariable models. Medication adherence was 97% by self-report, 96% by pill count, and 84% by urine monitoring. Eight patients had adverse events deemed possibly related to the study drug (5 placebo, 1 low-dose, 2 high-dose), and 6 patients reported at least 1 HSV outbreak (3 placebo, 3 low-dose, 0 high-dose). CONCLUSIONS Valacyclovir did not decrease systemic immune activation or inflammatory biomarkers in HIV-1/HSV-2-coinfected adults on suppressive ART. CLINICAL TRIALS REGISTRATION NCT01176409.

Inflammation and HIV Transmission in Sub-Saharan Africa

While the per-contact risk of sexual HIV transmission is relatively low, it is fourfold higher in sub-Saharan Africa, and this may partly explain the major global disparities that exist in HIV prevalence. Genital immune parameters are key determinants of HIV transmission risk, including epithelial integrity and the presence of highly HIV-susceptible intraepithelial or submucosal CD4+ T cell target cells. Biological parameters that may enhance mucosal HIV susceptibility in highly HIV-affected regions of sub-Saharan Africa include increased levels of mucosal inflammation, which can affect both epithelial integrity and target cell availability, as well as the increased mucosal surface area that is afforded by an intact foreskin, contraceptive choices, and intravaginal practices. There are multifactorial causes for increased mucosal inflammation, with the prevalence and nature of common co-infections being particularly relevant.

Association of HPV infection and clearance with cervicovaginal immunology and the vaginal microbiota

Cervical human papillomavirus (HPV) infection may increase HIV risk. Since other genital infections enhance HIV susceptibility by inducing inflammation, we assessed the impact of HPV infection and clearance on genital immunology and the cervico-vaginal microbiome. Genital samples were collected from 65 women for HPV testing, immune studies and microbiota assessment; repeat HPV testing was performed after 6 months. All participants were HIV-uninfected and free of bacterial STIs. Cytobrush-derived T cell and dendritic cell subsets were assessed by multiparameter flow cytometry. Undiluted cervico-vaginal secretions were used to determine cytokine levels by multiplex ELISA, and to assess bacterial community composition and structure by 16S rRNA gene sequence analysis. Neither HPV infection nor clearance were associated with broad differences in cervical T cell subsets or cytokines, although HPV clearance was associated with increased Langerhans cells and HPV infection with elevated IP-10 and MIG. Individuals with HPV more frequently had a high diversity cervico-vaginal microbiome (community state type IV) and were less likely to have an L. gasseri predominant microbiome. In summary, HPV infection and/or subsequent clearance was not associated with inflammation or altered cervical T cell subsets, but associations with increased Langerhans cells and the composition of the vaginal microbiome warrant further exploration.

Chemokine Levels in the Penile Coronal Sulcus Correlate with HIV-1 Acquisition and Are Reduced by Male Circumcision in Rakai, Uganda

Individual susceptibility to HIV is heterogeneous, but the biological mechanisms explaining differences are incompletely understood. We hypothesized that penile inflammation may increase HIV susceptibility in men by recruiting permissive CD4 T cells, and that male circumcision may decrease HIV susceptibility in part by reducing genital inflammation. We used multi-array technology to measure levels of seven cytokines in coronal sulcus (penile) swabs collected longitudinally from initially uncircumcised men enrolled in a randomized trial of circumcision in Rakai, Uganda. Coronal sulcus cytokine levels were compared between men who acquired HIV and controls who remained seronegative. Cytokines were also compared within men before and after circumcision, and correlated with CD4 T cells subsets in foreskin tissue. HIV acquisition was associated with detectable coronal sulcus Interleukin-8 (IL-8 aOR 2.26, 95%CI 1.04–6.40) and Monokine Induced by γ-interferon (MIG aOR 2.72, 95%CI 1.15–8.06) at the visit prior to seroconversion, and the odds of seroconversion increased with detection of multiple cytokines. Coronal sulcus chemokine levels were not correlated with those in the vagina of a man’s female sex partner. The detection of IL-8 in swabs was significantly reduced 6 months after circumcision (PRR 0.59, 95%CI 0.44–0.87), and continued to decline for at least two years (PRR 0.29, 95%CI 0.16–0.54). Finally, prepuce IL-8 correlated with increased HIV target cell density in foreskin tissues, including highly susceptible CD4 T cells subsets, as well as with tissue neutrophil density. Together, these data suggest that penile inflammation increases HIV susceptibility and is reduced by circumcision.

Distinct Effects of the Cervicovaginal Microbiota and Herpes Simplex Type 2 Infection on Female Genital Tract Immunology

Background Genital inflammation is a key determinant of human immunodeficiency virus (HIV) transmission, and may increase HIV-susceptible target cells and alter epithelial integrity. Several genital conditions that increase HIV risk are more prevalent in African, Caribbean, and other black (ACB) women, including bacterial vaginosis and herpes simplex virus type-2 (HSV-2) infection. Therefore, we assessed the impact of the genital microbiota on mucosal immunology in ACB women and microbiome-HSV-2 interactions. Methods Cervicovaginal secretions and endocervical cells were collected by cytobrush and Instead Softcup, respectively. T cells and dendritic cells were assessed by flow cytometry, cytokines by multiplex enzyme-linked immunosorbent assay (ELISA), and the microbiota by 16S ribosomal ribonucleic acid gene sequencing. Results The cervicovaginal microbiota of 51 participants were composed of community state types (CSTs) showing diversity (20/51; 39%) or predominated by Lactobacillus iners (22/51; 42%), L. crispatus (7/51; 14%), or L. gasseri (2/51; 4%). High-diversity CSTs and specific bacterial phyla (Gardnerella vaginalis and Prevotella bivia) were strongly associated with cervicovaginal inflammatory cytokines, but not with altered endocervical immune cells. However, cervical CD4+ T-cell number was associated with HSV-2 infection and a distinct cytokine profile. Conclusions This suggests that the genital microbiota and HSV-2 infection may influence HIV susceptibility through independent biological mechanisms.

Valacyclovir Therapy Does Not Reverse Herpes-Associated Alterations in Cervical Immunology: A Randomized, Placebo-Controlled Crossover Trial

Herpes simplex virus type 2 (HSV-2) infection is associated with a 3-fold increase in the risk of human immunodeficiency virus (HIV) acquisition, perhaps through alterations in mucosal HIV-susceptible target cells. We performed a clinical trial to assess the impact of herpes therapy on cervical immunology in HSV-2-infected, HIV-uninfected women from Africa or the Caribbean who were living in Toronto, Canada. Thirty participants received 1 g of valacyclovir orally each day for 2 months in a randomized double-blind, placebo-controlled, crossover trial. Valacyclovir did not reduce the number of cervical CD4(+) T cells, the number of dendritic cells, or the expression of proinflammatory cytokines and tended to increase the expression of the HIV coreceptor CCR5 and the activation marker CD69. Short-term valacyclovir therapy did not reverse HSV-2-associated alterations in genital immunology. Clinical Trials Registration. NCT00946556.

Effect of Intercurrent Infections and Vaccinations on Immune and Inflammatory Biomarkers Among Human Immunodeficiency Virus-Infected Adults on Suppressive Antiretroviral Therapy.

We used generalized estimating equations to quantify the impact of recent vaccination or intercurrent infections on immune and inflammatory biomarkers among 144 human immunodeficiency virus (HIV)-infected adults with HIV RNA < 50 copies/mL on antiretroviral therapy. These events were associated with a 2.244 µg/mL increase in high sensitivity C-reactive protein and should be routinely assessed in future studies.