Persistence of genital tract T cell responses in HIV-infected women on highly active antiretroviral therapy

Parallel studies of mucosal immunity in the reproductive and gastrointestinal mucosa of HIV-infected women

PROBLEM

The effects of HIV on the gastrointestinal tract (GIT), including CD4 depletion, epithelial disruption, and collagen deposition, are well documented and only partially reversed by combination antiretroviral therapy (cART). However, the effects of HIV on the female reproductive tract (FRT) are poorly understood, and most studies have focused on ectocervix and vagina without assessing the upper tract. Here, we investigated CD4⁺ T-cell frequency, phenotype, and HIV-specific T-cell responses in the endocervix and endometrium of HIV-infected women, comparing these tissues to the GIT.

METHOD OF STUDY

Mucosal samples and blood were obtained from 18 women: four who were HIV-positive and not on cART for at least 3 years prior to sampling, including two natural controllers (viral load [VL] undetectable and CD4 >350); nine women on cART with low to undetectable VL; and five HIV-uninfected women. Mucosal samples included terminal ileum, sigmoid colon, endocervical cytobrush, endocervical curettage, and endometrial biopsy. T-cell frequency, phenotypes, and HIV-specific T-cell responses were analyzed by multiparameter flow cytometry.

RESULTS

T-cell activation, measured by CD38/HLA-DR co-expression, remained significantly elevated in endometrium following cART, but was lower in gastrointestinal tissues. HIV-specific CD8⁺ T-cell responses were detected in ileum, colon, and endometrial tissues of women both on and off cART, and were of higher magnitude on those not on cART.

CONCLUSION

Our findings reveal differences in CD4⁺ T-cell frequencies, immune activation, and HIV-specific T-cell responses between the gastrointestinal and reproductive tracts, and highlight differences between HIV controllers and women on cART.

Tissue issues: mucosal T-cell responses in HIV-1 infection

PURPOSE OF REVIEW

This review summarizes our current understanding of HIV-1-specific T-cell responses in mucosal tissues, emphasizing recent work and specifically highlighting papers published over the past 18 months.

RECENT FINDINGS

Recent work has improved the standardization of tissue sampling approaches and provided new insights on the abundance, phenotype and distribution of HIV-1-specific T-cell populations in mucosal tissues. In addition, it has recently been established that some lymphocytes exist in tissues as "permanent resident" memory cells that differ from their counterparts in blood.

SUMMARY

HIV-1-specific T-cell responses have been extensively characterized; however, the vast majority of reports have focused on T-cells isolated from peripheral blood. Mucosal tissues of the genitourinary and gastrointestinal tracts serve as the primary sites of HIV-1 transmission, and provide "front line" barrier defenses against HIV-1 and other pathogens. In addition, the gastrointestinal tract remains a significant viral reservoir throughout the chronic phase of infection. Tissue-based immune responses may be critical in fighting infection, and understanding these defenses may lead to improved vaccines and immunotherapeutic strategies.

Mucosal Immunity in HIV/SIV Infection: T Cells, B Cells and Beyond

As our understanding of mucosal immunity increases, it is becoming clear that the host response to HIV-1 is more complex and nuanced than originally believed. The mucosal landscape is populated with a variety of specialized cell types whose functions include combating infectious agents while preserving commensal microbiota, maintaining barrier integrity, and ensuring immune homeostasis. Advances in multiparameter flow cytometry, gene expression analysis and bioinformatics have allowed more detailed characterization of these cell types and their roles in host defense than was previously possible. This review provides an overview of existing literature on immunity to HIV-1 and SIVmac in mucosal tissues of the female reproductive tract and the gastrointestinal tract, focusing on major effector cell populations and briefly summarizing new information on tissue resident memory T cells, T_reg, Th17, Th22 and innate lymphocytes (ILC), subsets that have been studied primarily in the gastrointestinal mucosa.

ART influences HIV persistence in the female reproductive tract and cervicovaginal secretions

The recently completed HIV prevention trials network study 052 is a landmark collaboration demonstrating that HIV transmission in discordant couples can be dramatically reduced by treating the infected individual with antiretroviral therapy (ART). However, the cellular and virological events that occur in the female reproductive tract (FRT) during ART that result in such a drastic decrease in transmission were not studied and remain unknown. Here, we implemented an in vivo model of ART in BM/liver/thymus (BLT) humanized mice in order to better understand the ability of ART to prevent secondary HIV transmission. We demonstrated that the entire FRT of BLT mice is reconstituted with human CD4+ cells that are shed into cervicovaginal secretions (CVS). A high percentage of the CD4+ T cells in the FRT and CVS expressed CCR5 and therefore are potential HIV target cells. Infection with HIV increased the numbers of CD4+ and CD8+ T cells in CVS of BLT mice. Furthermore, HIV was present in CVS during infection. Finally, we evaluated the effect of ART on HIV levels in the FRT and CVS and demonstrated that ART can efficiently suppress cell-free HIV-RNA in CVS, despite residual levels of HIV-RNA+ cells in both the FRT and CVS.

Relationship Between Genital Drug Concentrations and Cervical Cellular Immune Activation and Reconstitution in HIV-1-Infected Women on a Raltegravir Versus a Boosted Atazanavir Regimen

Determinants of HIV-infected women's genital tract mucosal immune health are not well understood. Because raltegravir (RAL) achieves relatively higher genital tract concentrations than ritonavir-boosted atazanavir (ATV), we examined whether an RAL-based regimen is associated with improved cervical immune reconstitution and less activation in HIV(+) women compared to an ATV-based regimen. Peripheral blood, cervical brushings, cervical-vaginal lavage (CVL), and cervical biopsies were collected from HIV(+) women on tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) and either RAL (n=14) or ATV (n=19) with CD4(+) T cells>300 cells/mm(3) and HIV RNA<48 copies/ml. HLA-DR(+)CD38(+) T cells were measured in blood and cervical cells using flow cytometry, CD4(+) and CD8(+) T cells were quantified in cervical biopsies by immunofluorescent analysis, and HIV RNA (VL), ATV, and RAL concentrations were measured in CVL. In a linear regression model of log(CVL concentration) versus both log(plasma concentration) and treatment group, the RAL CVL level was 519% (95% CI: 133, 1,525%) higher than for ATV (p<0.001). Genital tract VL was undetectable in 90% of subjects and did not differ by regimen. There were no significant differences between groups in terms of cervical %HLA-DR(+)CD38(+)CD4(+) or CD8(+) T cells, CD4(+) or CD8(+) T cells/mm(2), or CD4:CD8 ratio. After adjusting for treatment time and group, the CVL:plasma drug ratio was not associated with the cervical CD4:CD8 ratio or immune activation (p>0.6). Despite significantly higher genital tract penetration of RAL compared to ATV, there were no significant differences in cervical immune activation or reconstitution between women on these regimens, suggesting both drug regimens achieve adequate genital tract levels to suppress virus replication.

Effect of HIV infection and menopause status on raltegravir pharmacokinetics in the blood and genital tract

BACKGROUND

This study describes first dose and steady state pharmacokinetics of raltegravir (RAL) in cervicovaginal fluid (CVF) and blood plasma (BP).

METHODS

Three cohorts of women were enrolled sequentially in a single-site, open-label pharmacokinetic study of oral raltegravir 400 mg twice daily: HIV-negative premenopausal, HIV-infected premenopausal and HIV-infected post-menopausal women. BP and CVF were collected over 12 h after a single observed dose and at steady state. RAL concentrations were measured by HPLC-MS methods. Data are expressed as median (IQR). The ANOVA rank-sum test was used to evaluate between-group differences in steady state raltegravir exposure (area under the concentration-time curve over the 12-h dosing interval [AUC0-12 h]).

RESULTS

First dose pharmacokinetics were obtained in HIV-negative premenopausal women and HIV-infected post-menopausal women only. The median (IQR) BP AUC0-12 h was 3,099 (985-5,959) and 4,239 (2,781-13,695) ng•h/ml and the median (IQR) CVF AUC0-12 h was 1,720 (305-5,288) and 13,797 (11,066-19,563) ng•h/ml for HIV-negative premenopausal and HIV-infected post-menopausal women, respectively. All cohorts contributed to steady-state pharmacokinetic profiles. Median (IQR) BP AUC0-12 h did not differ between the groups: 8,436 (3,080-10,111), 5,761 (1,801-10,095) and 6,180 (5,295-8,282) ng•h/ml in HIV-negative premenopausal, HIV-infected premenopausal and HIV-infected post-menopausal women, respectively. There was a trend for lower CVF AUC0-12 h among HIV-negative women 3,164 (1,156-9,540) compared to 11,465 (9,725-17,138) and 9,568 (4,271-24,306) ng•h/ml HIV-infected premenopausal and HIV-infected post-menopausal women, respectively, but this was not statistically significant (P=0.08). HIV-negative premenopausal women had a median (IQR) CVF:BP AUC0-12 h ratio of 0.46 (0.2-1.1), whereas HIV-infected premenopausal and post-menopausal women had median (IQR) CVF:BP AUC0-12 h ratio of 3.9 (1.2-6.7) and 1.4 (0.7-4.3), respectively.

CONCLUSIONS

This is the first study to investigate RAL exposure in BP and CVF in premenopausal HIV-negative and pre- and post-menopausal HIV-infected women. These data indicate HIV and menopausal status may influence antiretroviral distribution into the female genital tract.

Twelve-Month Antiretroviral Therapy Suppresses Plasma and Genital Viral Loads but Fails to Alter Genital Levels of Cytokines, in a Cohort of HIV-Infected Rwandan Women

Background

Genital viral load (GVL) is the main determinant of sexual transmission of human immune-deficiency virus (HIV). The effect of antiretroviral therapy (ART) on local cervico-vaginal immunological factors associated with GVL is poorly described. We aimed to identify the risk factors of detectable GVL, and the impact of ART on HIV genital shedding and its correlates in a cohort of HIV-infected women, attending HIV care in Kigali, Rwanda.

Materials and Methods

All participants were evaluated for GVL, plasma viral load (PVL), CD4 count, various sexually-transmitted infections (STIs) at baseline and at month 12. Genital concentration of 19 cytokines and mRNA expression of APOBEC3G and BST2, two host HIV restriction factors, were evaluated at baseline in all participants. Cytokine levels were re-assessed at month 12 only in participants eligible for ART at baseline. Risk factors of GVL ≥40copies/mL at baseline and month 12 were assessed using logistic regression. Effect of 12-month ART on various local and systemic immunological parameters was examined using a paired t-test and McNemar as appropriate.

Results

96 of the 247 women enrolled in the study were eligible for ART. After 12 months of ART, PVL and GVL decreased to undetectable level in respectively 74 and 88% of treated participants. ART did not affect cytokine levels. HIV genital shedding occurred only when PVL was detectable. At baseline, GVL was independently associated with IL-1β after controlling for PVL, age and N. gonorrhea infection (95% CI 1.32-2.15) and at month 12 with MIP-1β (95% CI 0.96-21.32) after controlling for baseline GVL, PVL and month 12 IL-8.

Conclusion

Suppressive ART does not necessarily reduce genital level of immune activation. Minimizing all conditions favoring genital inflammation, including active detection and treatment of STIs, might reduce the risk of HIV transmission as supplement to the provision of potent ART.

HIV-1 RNA levels and antiretroviral drug resistance in blood and non-blood compartments from HIV-1-infected men and women enrolled in AIDS clinical trials group study A5077

BACKGROUND

Detectable HIV-1 in body compartments can lead to transmission and antiretroviral resistance. Although sex differences in viral shedding have been demonstrated, mechanisms and magnitude are unclear. We compared RNA levels in blood, genital-secretions and saliva; and drug resistance in plasma and genital-secretions of men and women starting/changing antiretroviral therapy (ART) in the AIDS Clinical Trials Group (ACTG) 5077 study.

METHODS

Blood, saliva and genital-secretions (compartment fluids) were collected from HIV-infected adults (≥ 13 years) at 14 United-States sites, who were initiating or changing ART with plasma viral load (VL) ≥ 2,000 copies/mL. VL testing was performed on all compartment fluids and HIV resistance genotyping on plasma and genital-secretions. Spearman rank correlations were used to evaluate concordance and Fisher's and McNemar's exact tests to compare VL between sexes and among compartments.

RESULTS

Samples were available for 143 subjects; 36% treated (23 men, 29 women) and 64% 'untreated' (40 men, 51 women). RNA detection was significantly more frequent in plasma (100%) than genital-secretions (57%) and saliva (64%) (P<0.001). A higher proportion of men had genital shedding versus women (78% versus 41%), and RNA detection was more frequent in saliva versus genital-secretions in women when adjusted for censoring at the limit of assay detection. Inter-compartment fluid VL concordance was low in both sexes. In 22 (13 men, 9 women) paired plasma-genital-secretion genotypes from treated subjects, most had detectable resistance in both plasma (77%) and genital-secretions (68%). Resistance discordance was observed between compartments in 14% of subjects.

CONCLUSIONS

HIV shedding and drug resistance detection prior to initiation/change of ART in ACTG 5077 subjects differed among tissues and between sexes, making the gold standard blood-plasma compartment assessment not fully representative of HIV at other tissue sites. Mechanisms of potential sex-dependent tissue compartmentalization should be further characterized to aid in optimizing treatment and prevention of HIV transmission.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00007488.

Is there an association between HIV-1 genital shedding and cervical intraepithelial neoplasia 2/3 among women on antiretroviral therapy?

OBJECTIVE

Given the high prevalence of cervical intraepithelial neoplasia (CIN) grade 2/3 among HIV-infected women, we sought to examine the relationship between CIN 2/3 and HIV-1 genital shedding among women on highly active antiretroviral therapy (HAART).

MATERIALS AND METHODS

Paired plasma and cervical wick specimens for HIV-1 RNA measurements were obtained from 44 HIV-infected women with biopsy-confirmed CIN 2/3 (cases) and 44 age-matched HIV-infected women with normal cervical findings on colposcopy (controls). All subjects tested negative for sexually transmitted infections and had been stable on HAART for at least 3 months. HIV-1 viral load was measured in both blood and cervical specimens using commercial real-time polymerase chain reaction assays.

RESULTS

Cervical intraepithelial neoplasia 2/3 was not significantly associated with the detection or magnitude of plasma or cervical HIV-1 RNA shedding. HIV was detected in the plasma in 10 cases (23%) and 10 controls (25%) (odds ratio = 1.0; 95% confidence interval = 0.33-3.1). Cervical HIV-1 was detected in 6 cases (13.6%) and 9 controls (20.4%) (odds ratio = 0.61; 95% confidence interval = 0.20-1.90). Mean HIV-1 concentration in cervical secretions among women with CIN 2/3 who shed was 2.93 log10 copies versus 2.72 among controls (p = .65).

CONCLUSIONS

Among women on HAART, we found no relationship between CIN 2/3 and HIV-1 genital shedding.

Cervical cancer prevention in low- and middle-income countries: feasible, affordable, essential

The annual worldwide burden of the preventable disease cervical cancer is more than 530,000 new cases and 275,000 deaths, with the majority occurring in low- and middle-income countries (LMIC), where cervical cancer screening and early treatment are uncommon. Widely used in high-income countries, Pap smear (cytology based) screening is expensive and challenging for implementation in LMICs, where lower-cost, effective alternatives such as visual inspection with acetic acid (VIA) and rapid human papillomavirus (HPV)-based screening tests offer promise for scaling up prevention services. Integrating HPV screening with VIA in "screen-and-treat-or-refer" programs offers the dual benefits of HPV screening to maximize detection and using VIA to triage for advanced lesions/cancer, as well as a pelvic exam to address other gynecologic issues. A major issue in LMICs is coinfection with human immunodeficiency virus (HIV) and HPV, which further increases the risk for cervical cancer and marks a population with perhaps the greatest need of cervical cancer prevention. Public-private partnerships to enhance the availability of cervical cancer prevention services within HIV/AIDS care delivery platforms through initiatives such as Pink Ribbon Red Ribbon present an historic opportunity to expand cervical cancer screening in LMICs.

Cervical cancer prevention in low- and middle-income countries: feasible, affordable, essential

The annual worldwide burden of the preventable disease cervical cancer is more than 530,000 new cases and 275,000 deaths, with the majority occurring in low- and middle-income countries (LMIC), where cervical cancer screening and early treatment are uncommon. Widely used in high-income countries, Pap smear (cytology based) screening is expensive and challenging for implementation in LMICs, where lower-cost, effective alternatives such as visual inspection with acetic acid (VIA) and rapid human papillomavirus (HPV)-based screening tests offer promise for scaling up prevention services. Integrating HPV screening with VIA in "screen-and-treat-or-refer" programs offers the dual benefits of HPV screening to maximize detection and using VIA to triage for advanced lesions/cancer, as well as a pelvic exam to address other gynecologic issues. A major issue in LMICs is coinfection with human immunodeficiency virus (HIV) and HPV, which further increases the risk for cervical cancer and marks a population with perhaps the greatest need of cervical cancer prevention. Public-private partnerships to enhance the availability of cervical cancer prevention services within HIV/AIDS care delivery platforms through initiatives such as Pink Ribbon Red Ribbon present an historic opportunity to expand cervical cancer screening in LMICs.

Immune responses to HIV in the female reproductive tract, immunologic parallels with the gastrointestinal tract, and research implications

The female reproductive tract is a major site of mucosa-associated lymphoid tissue and susceptibility to HIV infection, yet the tissue site(s) of infection and the impact of HIV infection on this important mucosal tissue remain poorly understood. CD4(+) T cells and other cell types expressing the major coreceptors for HIV, CCR5, and CXCR4 are abundant in both the lower reproductive tract (endocervix and vagina) and the upper tract (endocervix and uterus) and are highly susceptible to infection. Antiviral defenses in the female reproductive tract are mediated by a variety of soluble factors and by mucosal effector cells that differ phenotypically from their counterparts in blood. The immunologic characteristics of the female reproductive tract parallel those of the gut, where major HIV-related immunologic injury occurs. The susceptibility of the female reproductive tract to HIV infection and immunopathogenesis suggests important new avenues for further research.