The future of PrEP: novel long-acting HIV prevention agents for adolescent women.

Adolescent girls and young women in Africa are at high risk of HIV and should be considered a key population for HIV prevention initiatives. Oral Tenofovir/Emtricitabine as pre-exposure prophylaxis (PrEP) has been shown to be effective on an individual and population level among key populations in Europe, Australia, and the US. However, studies in sub-Saharan Africa in a generalised epidemic have been less promising with adherence to daily tablets identified as a major problem. Long-acting PrEP drugs are being developed as a response to this problem. The first of these long-acting agents, injectable Cabotegravir given every two months has shown superiority to oral PreP and has been approved by the US Food and Drug Administration (FDA). Another long-acting PrEP drug in development is Lenacapavir which is an investigational, first-in-class long-acting HIV-1 capsid inhibitor that can be given as a six-monthly injection. These long-acting drugs could be a highly effective public health HIV prevention intervention. If made readily available to a vulnerable population of adolescent young women who are at high risk of HIV they could play an important role in protecting this key population against HIV and potentially reduce the population level risk of HIV.

SARS-CoV-2 seroprevalence and implications for population immunity: Evidence from two Health and Demographic Surveillance System sites in Kenya, February-December 2022.

BACKGROUND: We sought to estimate SARS-CoV-2 antibody seroprevalence within representative samples of the Kenyan population during the third year of the COVID-19 pandemic and the second year of COVID-19 vaccine use. METHODS: We conducted cross-sectional serosurveys among randomly selected, age-stratified samples of Health and Demographic Surveillance System (HDSS) residents in Kilifi and Nairobi. Anti-spike (anti-S) immunoglobulin G (IgG) serostatus was measured using a validated in-house ELISA and antibody concentrations estimated with reference to the WHO International Standard for anti-SARS-CoV-2 immunoglobulin. RESULTS: HDSS residents were sampled in February-June 2022 (Kilifi HDSS N = 852; Nairobi Urban HDSS N = 851) and in August-December 2022 (N = 850 for both sites). Population-weighted coverage for ≥1 doses of COVID-19 vaccine were 11.1% (9.1-13.2%) among Kilifi HDSS residents by November 2022 and 34.2% (30.7-37.6%) among Nairobi Urban HDSS residents by December 2022. Population-weighted anti-S IgG seroprevalence among Kilifi HDSS residents increased from 69.1% (65.8-72.3%) by May 2022 to 77.4% (74.4-80.2%) by November 2022. Within the Nairobi Urban HDSS, seroprevalence by June 2022 was 88.5% (86.1-90.6%), comparable with seroprevalence by December 2022 (92.2%; 90.2-93.9%). For both surveys, seroprevalence was significantly lower among Kilifi HDSS residents than among Nairobi Urban HDSS residents, as were antibody concentrations (p < 0.001). CONCLUSION: More than 70% of Kilifi residents and 90% of Nairobi residents were seropositive for anti-S IgG by the end of 2022. There is a potential immunity gap in rural Kenya; implementation of interventions to improve COVID-19 vaccine uptake among sub-groups at increased risk of severe COVID-19 in rural settings is recommended.

URCHOICE: Preferences for Pre-Exposure Prophylaxis (PrEP) Options for HIV Prevention Among Kenyan men who have sex with men and Transgender Women in Nairobi, Kisumu and the Coast.

HIV prevention method preferences were evaluated among Kenyan men who have sex with men (MSM) and transgender women (TW) from three sites: Kisumu, Nairobi and the Coast. Information sessions detailing the attributes, duration of protection, route of administration and probable visibility were attended by 464 HIV negative participants, of whom 423 (median age: 24 years) agreed to be interviewed. Across pairwise comparisons daily PrEP was by far the least preferred (1%); quarterly injections (26%) and monthly pills (23%) were most preferred, followed by yearly implant (19%) and condoms (12%). When participants were "forced" to choose their most preferred PrEP option, only 10 (2.4%) chose the daily pill; more (37.1%) chose the quarterly injection than the monthly pill (34.8%) and the yearly implant (25.8%). TW preferred the yearly implant over the quarterly injection. To achieve the rates of PrEP uptake and adherence necessary for protecting large proportions of vulnerable MSM and TW, a variety of long-acting products should be developed and made accessible to appeal to a diversity of preferences.

Pre-exposure prophylaxis for transgender women and men who have sex with men: qualitative insights from healthcare providers, community organization-based leadership and end users in coastal Kenya.

Transgender women (TW) and men who have sex with men (MSM) in Kenya are disproportionately affected by human immunodeficiency virus (HIV) and would benefit substantially from pre-exposure prophylaxis (PrEP). We conducted focus group discussions (FGDs) with healthcare providers (HCPs) and TW/MSM leadership and in-depth interviews (IDIs) with PrEP-experienced MSM and TW to learn about perceived and actual barriers to PrEP programming. Eleven HCP and 10 TW/MSM leaders participated in FGDs before PrEP roll-out (January 2018) and 12 months later. Nineteen PrEP end-users (11 MSM and 8 TW) participated in IDIs. Topic guides explored PrEP knowledge, HIV acquisition risk, gender identity, motivation for PrEP uptake and adherence and PrEP-dispensing venue preferences. Braun and Clarke thematic analysis was applied. Four themes emerged: limited preparedness of HCPs to provide PrEP to TW and MSM, varied motivation for PrEP uptake and persistence among end users, lack of recognition of TW by HCPs and suggestions for PrEP programming improvement from all stakeholders. Providers' reluctance to prescribe PrEP to TW and distrust of TW towards providers calls for interventions to improve the capacity of service environments and staff HIV preventive care. Alternative locations for PrEP provision, including community-based sites, may be developed with TW/MSM leaders.

Low-Dose Acetylsalicylic Acid Reduces T Cell Immune Activation: Potential Implications for HIV Prevention.

Introduction: Acetylsalicylic acid (ASA) is a well-known and safe anti-inflammatory. At low-dose, it is prescribed to prevent secondary cardiovascular events in those with pre-existing conditions and to prevent preeclampsia. Little is known about how low-dose ASA affects the immune response. In this study, we followed women to assess how ASA use modifies T cells immune phenotypes in the blood and at the genital tract. Methods: HIV uninfected women from Kenya were enrolled in this study and followed for one month to assess baseline responses including systemic/mucosal baseline immune activation. Participants then received 81mg of ASA daily for 6 weeks to assess changes to T cell immune activation (systemic and mucosal) relative to baseline levels. Results: The concentration of ASA measured in the blood was 58% higher than the level measured at the female genital tract. In the blood, the level of ASA was inversely correlated with the following: the proportion of Th17 expressing HLA-DR (p=0.04), the proportion of effector CD4+ T cells expressing CCR5 (p=0.03) and the proportion of CD8+Tc17 expressing CCR5 (p=0.04). At the genital tract, ASA use correlated with a decreased of activated CD4+T cells [CD4+CCR5+CD161+ (p=0.02) and CD4+CCR5+CD95+ (p=0.001)]. Conclusion: This study shows that ASA use impacts the immune response in both the systemic and genital tract compartments. This could have major implications for the prevention of infectious diseases such as HIV, in which the virus targets activated T cells to establish an infection. This could inform guidelines on ASA use in women. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02079077.

"I wish to remain HIV negative": Pre-exposure prophylaxis adherence and persistence in transgender women and men who have sex with men in coastal Kenya.

BACKGROUND: Transgender women (TGW) and men who have sex with men (MSM) in sub-Saharan Africa have high HIV acquisition risks and can benefit from daily pre-exposure prophylaxis (PrEP). We assessed PrEP adherence by measuring tenofovir-diphosphate (TFV-DP) levels and explore motives for PrEP persistence in TGW and MSM. METHODS: Participants were enrolled in a one-year PrEP programme and made quarterly visits irrespective of whether they were still using PrEP. At their month 6 visit, participants provided a dried blood spot to test for TFV-DP levels; protective levels were defined as those compatible with ≥4 pills per week (700-1249 fmol/punch). Before TFV-DP levels were available, a sub-set of these participants were invited for an in-depth interview (IDI). Semi-structured IDI topic guides were used to explore motives to uptake, adhere to, and discontinue PrEP. IDI data were analyzed thematically. RESULTS: Fifty-three participants (42 MSM and 11 TGW) were enrolled. At month 6, 11 (20.7%) participants (8 MSM and 3 TGW) were lost to follow up or stopped taking PrEP. Any TFV-DP was detected in 62.5% (5/8) of TGW vs. 14.7% of MSM (5/34, p = 0.01). Protective levels were detected in 37.5% of TGW (3/8), but not in any MSM. Nineteen IDI were conducted with 7 TGW and 9 MSM on PrEP, and 1 TGW and 2 MSM off PrEP. Unplanned or frequent risky sexual risk behaviour were the main motives for PrEP uptake. Among participants on PrEP, TGW had a more complete understanding of the benefits of PrEP. Inconsistent PrEP use was attributed to situational factors. Motives to discontinue PrEP included negative reactions from partners and stigmatizing healthcare services. CONCLUSION: While MSM evinced greater adherence challenges in this PrEP programme, almost 40% of TGW were protected by PrEP. Given high HIV incidences in TGW these findings hold promise for TGW PrEP programming in the region.

PrEP interest and HIV-1 incidence among MSM and transgender women in coastal Kenya.

INTRODUCTION: There is emerging data on HIV-1 incidence among MSM in sub-Saharan Africa (SSA), but no known estimate of HIV-1 incidence among transgender women (TGW) in the region has yet been reported. We assessed HIV-1 incidence and pre-exposure prophylaxis (PrEP) interest in men who have sex with men exclusively (MSME), men who have sex with men and women (MSMW) and TGW in coastal Kenya. METHODS: HIV-1-seronegative individuals who had participated in an HIV testing study in 2016 were traced and retested in 2017 according to Kenyan guidelines. All participants were assigned male sex at birth and had male sex partners; additional data on gender identity and sexual orientation were obtained. We assessed the factors associated with HIV-1 acquisition using Poisson regression and calculated HIV-1 incidence in MSME, MSMW and TGW. PrEP interest was assessed through focus group discussions to characterize subcategories' perceived PrEP needs. RESULTS: Of the 168 cohort participants, 42 were classified as MSME, 112 as MSMW and 14 as TGW. Overall, HIV-1 incidence was 5.1 (95% confidence interval (CI): 2.6 to 9.8) per 100 person-years (PY): 4.5 (95% CI: 1.1 to 17.8] per 100 PY among MSME, 3.4 (95% CI: 1.3 to 9.1) per 100 PY among MSMW and 20.6 (95% CI: 6.6 to 63.8] per 100 PY among TGW. HIV-1 acquisition was associated with exclusive receptive anal intercourse (aIRR 13.0, 95% CI 1.9 to 88.6), history of an STI in preceding six months (aIRR 10.3, 95% CI 2.2 to 49.4) and separated/divorced marital status (aIRR 8.2 (95%: 1.1 to 62.2). Almost all (98.8%) participants were interested in initiating PrEP. MSME and TGW felt that PrEP would lead to increases in condomless anal or group sex. CONCLUSIONS: TGW had a very high HIV-1 incidence compared with MSME and MSMW. Subcategories of MSM anticipated different PrEP needs and post-PrEP risk behaviour. Further studies should assess if TGW may have been wrongly categorized as MSM in other HIV-1 incidence studies in the region.

Characterization of the Genital Mucosa Immune Profile to Distinguish Phases of the Menstrual Cycle: Implications for HIV Susceptibility.

BACKGROUND: Inflammation and immune activation are key factors in sexual transmission of human immunodeficiency virus (HIV). We sought to define the impact of hormonal cycling on the mucosal immune environment and HIV risk in sex workers with a natural menstrual cycle. METHODS: We compared soluble mucosal immune factors and cervical mononuclear cells during hormone titer-defined phases of the menstrual cycle among 37 sex workers from Nairobi, Kenya. Systemic and mucosal samples were collected 14 days apart to distinguish the follicular and luteal phases of the menstrual cycle, and phases were confirmed by hormone measurements. Vaginal concentrations of 19 immune modulators and cervical T-cell activation markers were measured. RESULTS: The follicular phase signature was characterized by an elevated CCL2 level, decreased interleukin 1α and interleukin 1ß cervical concentrations, and a significant increase in the proportion of CD4+ T cells that expressed CD69. The genital concentration of CCL2 was the best marker to distinguish the follicular from the luteal phase in univariate and multivariate analyses and remained independent of elevated genital inflammation and bacterial vaginosis. CONCLUSION: The follicular phase of the menstrual cycle was associated with an elevated CCL2 level and retention of resident memory CD4+ T cells, which has implications for increased susceptibility to HIV infection.

Using safe, affordable and accessible non-steroidal anti-inflammatory drugs to reduce the number of HIV target cells in the blood and at the female genital tract.

INTRODUCTION: At its basic level, HIV infection requires a replication-competent virus and a susceptible target cell. Elevated levels of vaginal inflammation has been associated with the increased risk of HIV infection as it brings highly activated HIV target cells (CCR5+CD4+ T cells; CCR5+CD4+CD161+ Th17 T cells) to the female genital tract (FGT) where they interact with HIV. Decreased HIV risk has been associated with a phenotype of decreased immune activation, called immune quiescence, described among Kenyan female sex workers who were intensely exposed to HIV yet remain uninfected. Current prevention approaches focus on limiting viral access. We took the novel HIV prevention approach of trying to limit the number of HIV target cells in the genital tract by reducing inflammation using safe, affordable and globally accessible anti-inflammatory drugs. METHODS: We hypothesized that the daily administration of low doses of acetylsalicylic acid (ASA 81 mg) or hydroxychloroquine (HCQ 200 mg) would reduce inflammation thereby decreasing HIV target cells at the FGT. Low-risk HIV seronegative women from Nairobi, Kenya were randomized for six weeks therapy of ASA (n = 37) or HCQ (n = 39) and tested to determine the impact on their systemic and mucosal immune environment. RESULTS: The results showed that HCQ use was associated with a significant reduction in the proportion of systemic T cells that were CCR5+CD4+ (p = 0.01) and Th17 (p = 0.01). In the ASA arm, there was a 35% and 28% decrease in the proportion of genital T cells that were CD4+CCR5+ (p = 0.017) and Th17 (p = 0.04) respectively. Proteomic analyses of the cervical lavage showed ASA use was associated with significantly reduced amount of proteins involved in the inflammatory response and cell recruitment at the mucosa, although none of the individual proteins passed multiple comparison correction. These changes were more apparent in women with Lactobacillus dominant microbiomes. CONCLUSION: Together, these data indicate that taking low-dose ASA daily was associated with significant reduction in HIV target cells at the FGT. This study provides proof-of-concept for a novel HIV-prevention approach that reducing inflammation using safe, affordable and globally accessible non-steroidal anti-inflammatory agents is associated with significant reduction in the proportion of HIV-target cells at the FGT.

Depressive symptoms and problematic alcohol and other substance use in 1476 gay, bisexual, and other MSM at three research sites in Kenya.

OBJECTIVE: Information on mental health and substance use challenges among gay, bisexual, and other MSM (GBMSM) is needed to focus resources on these issues and optimize services for HIV prevention and care. We determined factors associated with depressive symptoms and problematic alcohol and other substance use among GBMSM in Kenya. METHODS: Self-identified GBMSM in three HIV research studies in Kenya provided information on depressive symptoms [Patient Health Questionnaire 9 (PHQ-9)], alcohol use [Alcohol Use Disorder Identification Test (AUDIT)], and other substance use [Drug Abuse Screening Test 6 (DAST-6)]. Associations were evaluated using mixed effects Poisson regression. RESULTS: Of 1476 participants, 452 (31%) reported moderate-to-severe depressive symptoms (PHQ-9 ≥ 10), 637 (44%) hazardous alcohol use (AUDIT ≥ 8), and 749 (51%) problematic substance use (DAST-6 ≥ 1). Known HIV-positive status was not associated with these outcomes. Transactional sex was associated with hazardous alcohol use [adjusted prevalence ratio (aPR) 1.34, 95% confidence interval (CI) 1.12-1.60]. Childhood abuse and recent trauma were associated with moderate-to-severe depressive symptoms (aPR 1.43, 95% CI 1.10-1.86 and aPR 2.43, 95% CI 1.91-3.09, respectively), hazardous alcohol use (aPR 1.36, 95% CI 1.10-1.68 and aPR 1.60, 95% CI 1.33-1.93, respectively), and problematic substance use (aPR 1.32, 95% CI 1.09-1.60 and aPR 1.35, 95% CI 1.14-1.59, respectively). CONCLUSION: GBMSM in rights-constrained settings need culturally appropriate services for treatment and prevention of mental health and substance use disorders, in addition to human rights advocacy to prevent abuse. Mental health and substance use screening and treatment or referral should be an integral part of programs, including HIV prevention and treatment programs, providing services to GBMSM.

CD161 identifies polyfunctional Th1/Th17 cells in the genital mucosa that are depleted in HIV-infected female sex workers from Nairobi, Kenya.

CD161 identifies a subset of circulating Th17 cells that are depleted in the blood and gut of HIV-infected individuals. In the female reproductive tract (FRT), the pattern of CD161 expression on CD4+ cells remains unknown. Here, we characterized CD161 expression in the FRT of Kenyan female sex workers (FSW). Compared to the blood, CD161+CD4+ T cells were enriched in the FRT of uninfected FSWs. These cells were depleted in FRT of HIV-infected FSWs. Cervical CD161+ cells harboured an activated phenotype (CD69, CD95, HLA-DR) with elevated expression of tissue-homing markers (CCR6, ß7 integrin) and HIV co-receptor (CCR5). Mitogen-stimulated production of IL-17 confirmed the Th17 commitment of CD161+CD4+ T cells in the FRT with a predominance of polyfunctional Th1/Th17 cells. Here, we showed that the expression of CD161 on CD4+T cells is modulated at the FRT, but still identified a highly activated cellular subset, which differentiates into pro-inflammatory Th1/Th17 cells, expresses multiple HIV susceptibility markers and are depleted in HIV-infected individuals. The use of CD161 as a biomarker of HIV targets in the FRT reduces the need for functional assessment of cells and could have important implications in better understanding HIV pathogenesis and Th17 fate in the FRT of high-risk women.

The Impact of Sex Work Interruption on Blood-Derived T Cells in Sex Workers from Nairobi, Kenya.

BACKGROUND: Unprotected sexual intercourse exposes the female genital tract (FGT) to semen-derived antigens, which leads to a proinflammatory response. Studies have shown that this postcoital inflammatory response can lead to recruitment of activated T cells to the FGT, thereby increasing risk of HIV infection. OBJECTIVE: The purpose of this study was to evaluate the impact of sex work on activation and memory phenotypes of peripheral T cells among female sex workers (FSW) from Nairobi, Kenya. SUBJECTS: Thirty FSW were recruited from the Pumwani Sex Workers Cohort, 10 in each of the following groups: HIV-exposed seronegative (at least 7 years in active sex work), HIV positive, and New Negative (HIV negative, less than 3 years in active sex work). Blood was obtained at three different phases (active sex work, abstinence from sex work-sex break, and following resumption of sex work). Peripheral blood mononuclear cells were isolated and stained for phenotypic markers (CD3, CD4, CD8, and CD161), memory phenotype markers (CD45RA and CCR7), activation markers (CD69, HLA-DR, and CD95), and the HIV coreceptor (CCR5). T-cell populations were compared between groups. RESULTS: In HIV-positive women, CD8+CCR5+ T cells declined at the sex break period, while CD4+CD161+ T cells increased when returning to sex work. All groups showed no significant changes in systemic T-cell activation markers following the interruption of sex work, however, significant reductions in naive CD8+ T cells were noted. For each of the study points, HIV positives had higher effector memory and CD8+CD95+ T cells and lower naive CD8+ T cells than the HIV-uninfected groups. CONCLUSIONS: Interruption of sex work had subtle effects on systemic T-cell memory phenotypes.

Barriers to the uptake of postexposure prophylaxis among Nairobi-based female sex workers.

INTRODUCTION: Female sex workers (FSWs) in sub-Saharan Africa are at a particularly high risk for HIV infection. Postexposure prophylaxis (PEP) is available as part of an HIV care and prevention program through dedicated FSW clinics in Nairobi, Kenya, but is underutilized. We evaluated PEP knowledge, access, and adherence among clinic attendees. METHODS: An anonymous questionnaire was administered to unselected HIV-uninfected FSWs. Participants were dichotomized into high and low HIV risk categories based on self-reported sexual practices. Prior PEP use, knowledge, and adherence were then evaluated. RESULTS: One hundred and thirty-four HIV-uninfected FSWs participated, with 64 (48%) categorized as being at high risk for HIV acquisition. High-risk FSWs were less likely to have heard of or accessed PEP than lower risk FSWs (37.5 vs. 58.6%, P = 0.014; and 21.9 vs. 40.6%, P = 0.019, respectively). Among higher risk FSWs, those who had accessed PEP were more likely to report treatment for a genital infection (71.4 vs. 42.0%, P = 0.049) or sex with an HIV-infected man (62.5 vs. 37.5%, P = 0.042) during the last 6 months. However, only 35.7% of high-risk women accessing PEP completed a full course of treatment, and noncompleters were more likely to report prior unprotected sex with an HIV-infected man (P = 0.023). CONCLUSION: Despite freely available PEP for Nairobi-based FSWs, women at highest risk were less likely to have heard of PEP, access PEP, or complete the full course of therapy once initiated. Program delivery needs to be improved to ensure that FSW most at risk are able to benefit from this resource.

Elevated expression of LAG-3, but not PD-1, is associated with impaired iNKT cytokine production during chronic HIV-1 infection and treatment.

BACKGROUND: LAG-3 is a potent negative regulator of the immune response but its impact in HIV infection in poorly understood. Unlike exhaustion markers such as PD-1, Tim-3, 2B4 and CD160, LAG-3 is poorly expressed on bulk and antigen-specific T cells during chronic HIV infection and its expression on innate lymphocyte subsets is not well understood. The aim of this study was to assess LAG-3 expression and association with cellular dysfunction on T cells, NK cells and iNKT cells among a cohort of healthy and HIV-infected female sex workers in Nairobi, Kenya. RESULTS: Ex vivo LAG-3 expression was measured by multiparametric flow cytometry, and plasma cytokine/chemokine concentrations measured by bead array. Although LAG-3 expression on bulk T cells was significantly increased among HIV-infected women, the proportion of cells expressing the marker was extremely low. In contrast, LAG-3 was more highly expressed on NK and iNKT cells and was not reduced among women treated with ART. To assess the functional impact of LAG-3 on iNKT cells, iNKT cytokine production was measured in response to lipid (αGalCer) and PMA/Io stimulation by both flow cytometry and cytokine bead array. iNKT cytokine production is profoundly altered by both HIV infection and treatment, and LAG-3, but not PD-1, expression is associated with a reduction in iNKT IFNγ production. CONCLUSIONS: LAG-3 does not appear to mediate T cell exhaustion in this African population, but is instead expressed on innate lymphocyte subsets including iNKT cells. HIV infection alters iNKT cytokine production patterns and LAG-3 expression is uniquely associated with iNKT dysfunction. The continued expression of LAG-3 during treatment suggests it may contribute to the lack of innate immune reconstitution commonly observed during ART.

Early HIV-1 infection is associated with reduced frequencies of cervical Th17 cells.

BACKGROUND: The hallmark of HIV infection is progressive but variable rates of systemic and mucosal CD4 depletion, leading to immunodeficiency. The impact of early HIV infection on cervical CD4 T-cell populations in humans remains poorly described. METHODS: We analyzed cytobrush-derived immune cells by flow cytometry and cytokines in cervicovaginal lavage from participants in early HIV (<6 months postinfection), chronic HIV, and HIV-uninfected controls. RESULTS: CD4:CD8 ratios declined rapidly in both the cervix and the blood following HIV infection. In contrast, absolute cervical CD4 T-cell counts in early HIV were comparable to HIV-uninfected participants, declining only in chronic infection. Early HIV infection was associated with increases in RANTES and MIP3a in cervicovaginal fluids. Concurrently, slight increases in activated cells (CD38HLA-DR) and higher levels of CTLA4 expression on Tregs in the cervix were observed. Although study groups did not differ with respect to levels of CCR5, integrin B7, or CD69, the frequencies of Th17 cells (defined as CCR6CCR10) was reduced by >10-fold in early HIV infection and Th1 cells (defined as CCR6CXCR3) were reduced by >2-fold. Although CCR6CCR10 cells did not differ in HIV receptor expression, these cells produced higher levels of interferon gamma and interleukin 17. CONCLUSIONS: These data support the model of initial CD4 T-cell depletion followed by overall T-cell influx in response to infection and concomitant increases in immune activation, inflammation, and regulatory markers. These data are among the earliest characterization of the cellular milieu in the female genital tract following male-to-female HIV transmission.

Enrichment of LAG-3, but not PD-1, on double negative T cells at the female genital tract.

PROBLEM: The expression of inhibitory markers such as LAG-3 and PD-1 on T lymphocytes regulates immune function. Their expression at the genital mucosa is poorly understood, but regulation of immune activation at the female genital tract likely controls susceptibility to sexually transmitted infections. METHOD OF STUDY: Cervical mononuclear cells were phenotyped by flow cytometry. Concentrations of cytokines were determined in cervical-vaginal lavage samples by bead array. RESULTS: LAG-3 expression was significantly elevated at the genital mucosa and was associated with expression of CCR5 and CD69. Double negative (DN) T cells expressed the highest levels of LAG-3, but not PD-1, and were more activated than other T lymphocytes. CONCLUSION: The elevated expression of LAG-3 at the genital tract suggests it may regulate T-cell activation, and identify cells susceptible to HIV infection. The enrichment of LAG-3 on DN T cells suggests LAG-3 may contribute to the immunoregulatory activity of these cells.

HIV-1 clade D is associated with increased rates of CD4 decline in a Kenyan cohort.

HIV-1 is grouped phylogenetically into clades, which may impact rates of HIV-1 disease progression. Clade D infection in particular has been shown to be more pathogenic. Here we confirm in a Nairobi-based prospective female sex worker cohort (1985-2004) that Clade D (n = 54) is associated with a more rapid CD4 decline than clade A1 (n = 150, 20.6% vs 13.4% decline per year, 1.53-fold increase, p = 0.015). This was independent of "protective" HLA and country of origin (p = 0.053), which in turn were also independent predictors of the rate of CD4 decline (p = 0.026 and 0.005, respectively). These data confirm that clade D is more pathogenic than clade A1. The precise reason for this difference is currently unclear, and requires further study. This is first study to demonstrate difference in HIV-1 disease progression between clades while controlling for protective HLA alleles.

Reduced cellular susceptibility to in vitro HIV infection is associated with CD4+ T cell quiescence.

BACKGROUND: HIV preferentially establishes productive infection in activated CD4+ T cells. Since proportions of activated CD4+ T cells vary between individuals, this study aimed to determine if individuals with a greater proportion of activated CD4+ T cells would be more susceptible to in vitro HIV infection. METHODOLOGY/PRINCIPAL FINDINGS: Unstimulated peripheral blood mononuclear cells (PBMC) from various donors were inoculated with HIV(ML1956)in vitro. HIV replication was evaluated by HIV p24 ELISA of culture supernatants and intracellular staining for HIV p24, which was detected by flow cytometry. Baseline T cell phenotypes and infected cell phenotypes were also evaluated by flow cytometry. Ex vivo phenotyping at the time of blood draw showed that elevated T cell activation and reduced Tregs were associated with increased cellular susceptibility to in vitro infection. Furthermore, the infected CD4+ T cell population was enriched for activated cells. CONCLUSION/SIGNIFICANCE: These data suggest that CD4+ T cell quiescence provides an environment less conducive to the establishment of HIV infection by limiting the pool of activated target cells.

Altered dendritic cell-natural killer interaction in Kenyan sex workers resistant to HIV-1 infection.

BACKGROUND: Natural killer (NK) cells are members of the innate immune system that play an important role in the defense against viral infection. They are also involved in the regulation of adaptive immune responses through cytokine secretion and the interaction with antigen-presenting cells. However, their role in HIV infection is only partially understood. OBJECTIVE: Here we studied the phenotype and function of NK cells of highly HIV-exposed but seronegative (HESN) uninfected commercial sex workers from Kenya who can be epidemiologically defined as relatively resistant to HIV infection. DESIGN: The purpose of this study was to gain insight into the role of NK cells in mediating resistance to HIV-1. This information can be used to better understand protection from infection which can be used for informing future design of effective prophylactics and therapeutics for HIV. METHODS: Whole blood samples were collected from study participants and isolated NK cells and dendritic cells were used in assays for phenotyping and cell function. RESULTS: Activated NK cells from resistant women killed autologous immature dendritic cells more efficiently and also secreted more interferon (IFN)-γ than those of uninfected, susceptible women. Interestingly, NK cells from HIV-resistant women were significantly more effective in inducing secretion of IL-12 in immature dendritic cells. CONCLUSIONS: These data suggest that an altered NK cell-dendritic cell interaction plays an important role in the protection from infection with HIV-1.

Characterization of a human cervical CD4+ T cell subset coexpressing multiple markers of HIV susceptibility.

The HIV pandemic disproportionately affects women, with most infections acquired through receptive vaginal sex. Although the target cells by which HIV establishes infection in the female genital tract remain poorly defined, it is known that immune activation results in CD4(+) T cells with enhanced susceptibility, as does expression of the mucosal integrin α4ß7 and the HIV coreceptor CCR5. Blood and cervical cytobrush specimens were collected from female sex workers (FSWs) in Nairobi, Kenya. Genital infection diagnostics were performed, T cell populations were defined by multiparameter flow cytometry based on their expression of surface receptors relevant to mucosal homing and/or HIV acquisition, and cytokine production was assayed by intracellular cytokine staining. The integrin α4ß7 was expressed on 26.0% of cervical CD4(+) T cells, and these cells were more likely to express both the HIV coreceptor CCR5 (p < 0.0001) and the early activation marker CD69 (p < 0.0001) but not CXCR4 (p = 0.34). Cervical Th17 frequencies were enhanced compared with blood (7.02 versus 1.24%; p < 0.0001), and cervical IL-17A(+) CD4(+) T cells preferentially coexpressed α4ß7 and CCR5. Expression of IFN-γ and IL-22 was greater in cervical Th17 cells than in blood Th17 cells. In keeping with the hypothesis that these cells are preferential HIV targets, gp120 preferentially bound CCR5(+) cervical T cells, and cervical Th17 cells were almost completely depleted in HIV(+) FSWs compared with HIV(-) FSWs. In summary, a subset of Th17 CD4(+) T cells in the cervical mucosa coexpresses multiple HIV susceptibility markers; their dramatic depletion after HIV infection suggests that these may serve as key target cells during HIV transmission.