Endocervical Regulatory T Cells Are Associated With Decreased Genital Inflammation and Lower HIV Target Cell Abundance.

Regulatory T cells (Tregs) play important roles in tissue homeostasis, but few studies have investigated tissue Tregs in the context of genital inflammation, HIV target cell density, and vaginal microbiota in humans. In women from Nairobi (n=64), the proportion of CD4+ CD25+ CD127low Tregs in the endocervix correlated with those in blood (r=0.31, p=0.01), with a higher Treg frequency observed in the endocervix (median 3.8 vs 2.0%, p<0.0001). Most Tregs expressed FOXP3 in both compartments, and CTLA-4 expression was higher on endocervical Tregs compared to blood (median 50.8 vs 6.0%, p<0.0001). More than half (34/62, 55%) of participants displayed a non-Lactobacillus dominant vaginal microbiota, which was not associated with endocervical Tregs or CD4+ T cell abundance. In a multivariable linear regression, endocervical Treg proportions were inversely associated with the number of elevated pro-inflammatory cytokines (p=0.03). Inverse Treg associations were also observed for specific cytokines including IL-1ß, G-CSF, Eotaxin, IL-1RA, IL-8, and MIP-1 ß. Higher endocervical Treg proportions were associated with lower abundance of endocervical CD4+ T cells (0.30 log10 CD4+ T cells per log10 Treg, p=0.00028), with a similar trend for Th17 cells (p=0.09). Selectively increasing endocervical Tregs may represent a pathway to reduce genital tract inflammation in women.

Rectal microbiota diversity in Kenyan MSM is inversely associated with frequency of receptive anal sex, independent of HIV status.

OBJECTIVE: Both HIV infection and identifying as MSM have been linked to altered rectal microbiota composition, but few studies have studied sexual behavioural associations with rectal microbiota within MSM. In addition, most rectal microbiota studies in MSM have been limited geographically to Europe and North America, and replication of findings in lower and middle-income countries is lacking. DESIGN: A cross-sectional study. METHODS: We enrolled MSM from Nairobi, Kenya, and determined their HIV/sexually transmitted infection status. Rectal specimens were obtained for 16s rRNA sequencing of the rectal microbiota, and sexual behaviour was characterized using a standardized questionnaire. Microbiome differences were modelled using nonparametric statistics, Bray-Curtis ecological distance metrics and analyses of differential taxa abundance. Multivariable linear regression was used to model HIV status and recent sexual activity as predictors of alpha diversity, controlling for a range of covariates. RESULTS: Alpha diversity was consistently lower in Kenyan HIV-infected MSM (n = 80), including those on antiretroviral therapy (ART) compared with HIV-uninfected MSM. A statistical trend was observed for clustering of HIV status by Prevotella or Bacteroides dominance (P = 0.13). Several taxa were enriched in HIV-positive men, including Roseburia, Lachnospira, Streptococcus and Granulicatella. Receptive anal sex with several types of sexual partners (paying, regular, casual) was associated with lower Chao1 and Simpson diversity, independent of HIV status, while HIV infection was associated lower Chao1 (P = 0.030) but not Simpson diversity (P = 0.49). CONCLUSION: Both HIV infection and sexual behaviour were associated with rectal microflora alpha diversity, in particular richness, but not Prevotella spp. dominance, in Kenyan MSM. Associations were more robust for sexual behaviour.

Integrin α4ß7 expression on peripheral blood CD4+ T cells predicts HIV acquisition and disease progression outcomes.

The gastrointestinal (GI) mucosa is central to HIV pathogenesis, and the integrin α4ß7 promotes the homing of immune cells to this site, including those that serve as viral targets. Data from simian immunodeficiency virus (SIV) animal models suggest that α4ß7 blockade provides prophylactic and therapeutic benefits. We show that pre-HIV infection frequencies of α4ß7+ peripheral blood CD4+ T cells, independent of other T cell phenotypes and genital inflammation, were associated with increased rates of HIV acquisition in South African women. A similar acquisition effect was observed in a Kenyan cohort and in nonhuman primates (NHPs) after intravaginal SIV challenge. This association was stronger when infection was caused by HIV strains containing V2 envelope motifs with a preference for α4ß7 binding. In addition, pre-HIV α4ß7+ CD4+ T cells predicted a higher set-point viral load and a greater than twofold increased rate of CD4+ T cell decline. These results were confirmed in SIV-infected NHPs. Increased frequencies of pre-HIV α4ß7+ CD4+ T cells were also associated with higher postinfection expression of lipopolysaccharide binding protein, a microbial translocation marker, suggestive of more extensive gut damage. CD4+ T cells expressing α4ß7 were rapidly depleted very early in HIV infection, particularly from the GI mucosa, and were not restored by early antiretroviral therapy. This study provides a link between α4ß7 expression and HIV clinical outcomes in humans, in line with observations made in NHPs. Given the availability of a clinically approved anti-α4ß7 monoclonal antibody for treatment of inflammatory bowel disease, these data support further evaluation of targeting α4ß7 integrin as a clinical intervention during HIV infection.

HIV-1 subtype diversity based on envelope C2V3 sequences from Kenyan patients on highly active antiretroviral therapy.

There is a continuous need to genetically characterize the HIV strains in circulation in order to assess interventions and inform vaccine discovery. We partially sequenced the envelope C2V3 gene from a total of 59 Kenyan patients on highly active antiretroviral treatment (HAART) and determined HIV subtypes using both the JPHMM subtyping tool and the phylogenetic method. HIV-1 subtype A1 was the predominant strain in circulation, representing 65.5% and 74.5% of all isolates as determined by JPHMM and phylogenetic methods, respectively. Subtypes C and D were the next most prevalent pure strains at 9.1% each by both methods. JPHMM identified 9.1% of the isolates as recombinant. Four isolates had short sequences not covering the entire C2V3 region and were thus not subtyped. From this study, subtype A viruses are still the predominant HIV-1 strains in local circulation in Kenya. Constant surveillance is needed to update molecular trends under continuing HAART scale-up.

Co-Infection Burden of Hepatitis C Virus and Human Immunodeficiency Virus among Injecting Heroin Users at the Kenyan Coast.

BACKGROUND: Injection drug use is steadily rising in Kenya. We assessed the prevalence of both human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) infections among injecting heroin users (IHUs) at the Kenyan Coast. METHODS: A total of 186 IHUs (mean age, 33 years) from the Omari rehabilitation center program in Malindi were consented and screened for HIV-1 and HCV by serology and PCR and their CD4 T-cells enumerated by FACS. RESULTS: Prevalence of HIV-1 was 87.5%, that of HCV was 16.4%, co-infection was 17.9% and 18/152 (11.8%) were uninfected. Only 5.26% of the HIV-1 negative injectors were HCV positive. Co-infection was higher among injectors aged 30 to 40 years (20.7%) and among males (22.1%) than comparable groups. About 35% of the injectors were receiving antiretroviral treatment (ART). Co-infection was highest among injectors receiving D4T (75%) compared to those receiving AZT (21.6%) or TDF (10.5%) or those not on ART (10.5%). Mean CD4 T-cells were 404 (95% CI, 365 - 443) cells/mm3 overall, significantly lower for co-infected (mean, 146; 95% CI 114 - 179 cells/mm3) than HIV mono infected (mean, 437, 95% CI 386 - 487 cells/mm3, p<0.001) or uninfected (mean, 618, 95% CI 549 - 687 cells/mm3, p<0.001) injectors and lower for HIV mono-infected than uninfected injectors (p=0.002). By treatment arm, CD4 T-cells were lower for injectors receiving D4T (mean, 78; 95% CI, 0.4 - 156 cells/mm3) than TDF (mean 607, 95% CI, 196 - 1018 cells/mm3, p=0.005) or AZT (mean 474, 95% CI -377 - 571 cells/mm3, p=0.004). CONCLUSION: Mono and dual infections with HIV-1 and HCV is high among IHUs in Malindi, but ART coverage is low. The co-infected IHUs have elevated risk of immunodeficiency due to significantly depressed CD4 T-cell numbers. Coinfection screening, treatment-as-prevention for both HIV and HCV and harm reduction should be scaled up to alleviate infection burden.

Genotypic Variability of HIV-1 Reverse Transcriptase Gene from Long-Term Antiretroviral-Experienced Patients in Kenya.

There is continuous need to track genetic profiles of HIV strains circulating in different geographic settings to hasten vaccine discovery and inform public health and intervention policies. We partially sequenced the reverse transcriptase region of the HIV-1 pol gene from a total of 54 Kenyan patients aged 18-56 years who continued highly active antiretroviral treatment (HAART) for between 8 and 102 months. Subtyping was done using both the JPHMM tool and phylogenetic method. HIV-1 subtype A1 was the predominant strain in circulation, representing 57.4% and 70.4% of all isolates as determined by JPHMM and phylogenetic methods, respectively. Subtypes D (14.8%, 7.4%), C (5.6%, 9.3%), and A2 (0%, 5.6%) were determined at respective prevalence by both methods. JPHMM identified 22.2% of the isolates as recombinants. This surveillance focused on the RT gene and reaffirms the predominance of subtype A and an increasing proportion of recombinant strains in the Kenyan epidemic.

Implementation and Operational Research: Correlates of Adherence and Treatment Failure Among Kenyan Patients on Long-term Highly Active Antiretroviral Therapy.

BACKGROUND: Universal access to highly active antiretroviral therapy (HAART) is still elusive in most developing nations. We asked whether peer support influenced adherence and treatment outcome and if a single viral load (VL) could define treatment failure in a resource-limited setting. METHODS: A multicenter longitudinal and cross-sectional survey of VL, CD4 T cells, and adherence in 546 patients receiving HAART for up to 228 months. VL and CD4 counts were determined using m2000 Abbott RealTime HIV-1 assay and FACS counters, respectively. Adherence was assessed based on pill count and on self-report. RESULTS: Of the patients, 55.8%, 22.2%, and 22% had good, fair, and poor adherence, respectively. Adherence, peer support, and regimen, but not HIV disclosure, age, or gender, independently correlated with VL and durability of treatment in a multivariate analysis (P < 0.001). Treatment failure was 35.9% using sequential VL but ranged between 27% and 35% using alternate single VL cross-sectional definitions. More patients failed stavudine (41.2%) than zidovudine (37.4%) or tenofovir (28.8%, P = 0.043) treatment arms. Peer support correlated positively with adherence (χ(2), P < 0.001), with nonadherence being highest in the stavudine arm. VL before the time of regimen switch was comparable between patients switching and not switching treatment. Moreover, 36% of those switching still failed the second-line regimen. CONCLUSION: Weak adherence support and inaccessible VL testing threaten to compromise the success of HAART scale-up in Kenya. To hasten antiretroviral therapy monitoring and decision making, we suggest strengthening patient-focused adherence programs, optimizing and aligning regimen to WHO standards, and a single point-of-care VL testing when multiple tests are unavailable.