Publications

Heme oxygenase-1 (HO-1) is an anti-inflammatory enzyme that maintains homeostasis during cellular stress. Given previous findings that shorter length variants of a HO-1 promoter region GT(n) microsatellite polymorphism are associated with increased HO-1 expression in cell lines, we hypothesized that shorter variants would also be associated with increased levels of HO-1 expression, less inflammation and lower levels of inflammation-associated viral replication in human immunodeficiency virus (HIV)-infected subjects. Healthy donors (n = 20) with shorter GT(n) repeats had higher HO-1 mRNA transcript in peripheral blood mononuclear cells stimulated with lipopolysaccharide (r = -0.38, P = 0.05). The presence of fewer GT(n) repeats in subjects with untreated HIV disease was associated with higher HO-1 mRNA levels in peripheral blood (r = -0.41, P = 0.02); similar observations were made in CD14(+) monocytes from antiretroviral-treated subjects (r = -0.36, P = 0.04). In African-Americans, but not Caucasians, greater GT(n) repeats were correlated with higher soluble CD14 levels during highly active antiretroviral therapy (r = 0.38, P = 0.007) as well as higher mean viral load off-therapy (r = 0.24, P = 0.04). These data demonstrate that the HO-1 GT(n) microsatellite polymorphism is associated with higher levels of HO-1 expression and that this pathway may have important effects on the association between inflammation and HIV replication.

The human gut mucosa is a major site of human immunodeficiency virus (HIV) infection and infection-associated pathogenesis. Increasing evidence shows that natural killer (NK) cells have an important role in control of HIV infection, but the mechanism(s) by which they mediate antiviral activity in the gut is unclear. Here, we show that two distinct subsets of NK cells exist in the gut, one localized to intraepithelial spaces (intraepithelial lymphocytes, IELs) and the other to the lamina propria (LP). The frequency of both subsets of NK cells was reduced in chronic infection, whereas IEL NK cells remained stable in spontaneous controllers with protective killer immunoglobulin-like receptor/human leukocyte antigen genotypes. Both IEL and LP NK cells were significantly expanded in immunological non-responsive patients, who incompletely recovered CD4+ T cells on highly active antiretroviral therapy (HAART). These data suggest that both IEL and LP NK cells may expand in the gut in an effort to compensate for compromised CD4+ T-cell recovery, but that only IEL NK cells may be involved in providing durable control of HIV in the gut.

BACKGROUND

East Africa has experienced a rapid expansion in access to antiretroviral therapy (ART) for HIV-infected patients. Regionally representative socio-demographic, laboratory and clinical characteristics of patients accessing ART over time and across sites have not been well described.

METHODS

We conducted a cross-sectional analysis of characteristics of HIV-infected adults initiating ART between 2002 and 2009 in Kenya, Uganda and Tanzania and in the International Epidemiologic Databases to Evaluate AIDS Consortium. Characteristics associated with advanced disease (defined as either a CD4 cell count level of less than 50 cells/mm3 or a WHO Stage 4 condition) at the time of ART initiation and use of stavudine (D4T) or nevirapine (NVP) were identified using a log-link Poisson model with robust standard errors.

RESULTS

Among 48,658 patients (69% from Kenya, 22% from Uganda and 9% from Tanzania) accessing ART at 30 clinic sites, the median age at the time of ART initiation was 37 years (IQR: 31-43) and 65% were women. Pre-therapy CD4 counts rose from 87 cells/mm3 (IQR: 26-161) in 2002-03 to 154 cells/mm3 (IQR: 71-233) in 2008-09 (p<0.001). Accessing ART at advanced disease peaked at 35% in 2005-06 and fell to 27% in 2008-09. D4T use in the initial regimen fell from a peak of 88% in 2004-05 to 59% in 2008-09, and a greater extent of decline was observed in Uganda than in Kenya and Tanzania. Self-pay for ART peaked at 18% in 2003, but fell to less than 1% by 2005. In multivariable analyses, accessing ART at advanced immunosuppression was associated with male sex, women without a history of treatment for prevention of mother to child transmission (both as compared with women with such a history) and younger age after adjusting for year of ART initiation and country of residence. Receipt of D4T in the initial regimen was associated with female sex, earlier year of ART initiation, higher WHO stage, and lower CD4 levels at ART initiation and the absence of co-prevalent tuberculosis.

CONCLUSIONS

Public health ART services in east Africa have improved over time, but the fraction of patients accessing ART with advanced immunosuppression is still high, men consistently access ART with more advanced disease, and D4T continues to be common in most settings. Strategies to facilitate access to ART, overcome barriers among men and reduce D4T use are needed.

OBJECTIVE AND DESIGN

Increasing evidence supports a parallel between HIV-1 infection and immune aging, which is particularly apparent with common changes in naive versus memory T-cell proportions. Here, we aimed at refining the value of common T-cell-associated markers of immunosenescence during HIV disease progression or aging, and at exploring further the impact in this context of old age as well as cytomegalovirus (CMV) co-infection, which is predominant in HIV-1-infected individuals.

METHODS

Frequencies of naive or CD57(+) memory T cells as well as the magnitude of CMV-pp65 T cells were measured in HIV-1-infected patients grouped according to disease progression status, treatment and age.

RESULTS

Our results indicate that the decline in naive T-cell levels rather than the accumulation of CD57(+) senescent T cells identifies best the premature development of an immunosenescence phenotype with HIV disease progression. Moreover, advanced age or mounting of strong CMV-specific responses impact independently on CD4(+) T-cell counts and recovery with antiretroviral therapy.

CONCLUSIONS

The present findings indicate that HIV-1 infection amplifies the effect of age on naive T-cell levels, and highlight the constraint on the capacity of treated patients to reconstitute their CD4(+) T-cell compartment due to age and CMV co-infection.

We previously found an association between faster CD4+ T-cell recovery in HIV-infected patients receiving combination antiretroviral therapy (cART) and interleukin-7 receptor-α (IL-7Rα) haplotype-2 in a predominantly Caucasian cohort. This study aims to determine whether this association was also significant in Africans. Patients were recruited from the Uganda AIDS Rural Treatment Outcomes (UARTO) cohort (n=352). We used survival analysis and linear mixed modelling (LMM) to determine factors associated with CD4 T-cell recovery. Eight IL-7Rα single-nucleotide polymorphisms (SNPs) were genotyped in both Africans and Caucasians (n=57). Soluble (s)IL-7Rα levels were measured by ELISA. In UARTO, IL-7Rα haplotype-2 was associated with slower CD4 T-cell recovery following cART by using survival analysis (P=0.020) and no association was found with LMM (P=0.958). The tagging-SNP for IL-7Rα haplotype-2 (rs6897932) was associated with decreased sIL-7Rα (P<0.001). The haplotypes for the IL-7Rα were significantly different in Africans and Caucasians. Using IL-7Rα genotypes we found slower CD4 T-cell recovery in UARTO patients was still associated with rs6897932 (P=0.009) and rs3194051 was associated with faster CD4 T-cell recovery (P=0.006). Unlike Caucasians, we did not demonstrate a significant association between IL-7Rα haplotype 2 and faster CD4 T-cell recovery in Africans. The IL-7Rα SNPs associated with CD4 T-cell recovery following cART differ in African and Caucasian cohorts.

Gut-associated lymphoid tissue (GALT) is a major site of HIV replication and CD4(+) T cell depletion. Furthermore, microbial translocation facilitated by mucosal damage likely contributes to the generalized immune activation observed in HIV infection. Regulatory T cells (Treg) help maintain homeostasis and suppress harmful immune activation during infection; however, in the case of persistent viral infections such as HIV, their role is less clear. Although a number of studies have examined Treg in blood during chronic infection, few have explored Treg in the gastrointestinal mucosa. For this study, paired blood and rectal biopsy samples were obtained from 12 HIV noncontrollers (viral load of >10,000 copies/ml plasma), 10 HIV controllers (viral load of <500 copies/ml plasma for more than 5 years), and 12 HIV seronegative control subjects. Noncontrollers had significantly higher percentages of Treg in rectal mononuclear cells (RMNC), but not in blood, compared to seronegative subjects (P = 0.001) or HIV controllers (P = 0.002). Mucosal Treg positively correlated with viral load (P = 0.01) and expression of immune activation markers by CD4(+) (P = 0.01) and CD8(+) (P = 0.07) T cells. Suppression assays indicated that mucosal and peripheral Treg of noncontrollers and controllers maintained their capacity to suppress non-Treg proliferation to a similar extent as Treg from seronegative subjects. Together, these findings reveal that rather than experiencing depletion, mucosal Treg frequency is enhanced during chronic HIV infection and is positively correlated with viral load and immune activation. Moreover, mucosal Treg maintain their suppressive ability during chronic HIV infection, potentially contributing to diminished HIV-specific T cell responses and viral persistence.