Publications

A rare subset of human immunodeficiency virus (HIV)-infected individuals maintains undetectable HIV RNA levels without therapy ("elite controllers"). To clarify the role of T-cell responses in mediating virus control, we compared HLA class I polymorphisms and HIV-specific T-cell responses among a large cohort of elite controllers (HIV-RNA < 75 copies/ml), "viremic" controllers (low-level viremia without therapy), "noncontrollers" (high-level viremia), and "antiretroviral therapy suppressed" individuals (undetectable HIV-RNA levels on antiretroviral therapy). The proportion of CD4(+) and CD8(+) T cells that produce gamma interferon (IFN-gamma) and interleukin-2 (IL-2) in response to Gag and Pol peptides was highest in the elite and viremic controllers (P < 0.0001). Forty percent of the elite controllers were HLA-B*57 compared to twenty-three percent of viremic controllers and nine percent of noncontrollers (P < 0.001). Other HLA class I alleles more common in elite controllers included HLA-B*13, HLA-B*58, and HLA-B*81 (P < 0.05 for each). Within elite and viremic controller groups, those with protective class I alleles had higher frequencies of Gag-specific CD8(+) T cells than those without these alleles (P = 0.01). Noncontrollers, with or without protective alleles, had low-level CD8(+) responses. Thus, certain HLA class I alleles are enriched in HIV controllers and are associated with strong Gag-specific CD8(+)IFN-gamma(+)IL-2(+) T cells. However, the absence of evidence of T cell-mediated control in many controllers suggests the presence of alternative mechanisms for viral control in these individuals. Defining mechanisms for virus control in "non-T-cell controllers" might lead to insights into preventing HIV transmission or preventing virus replication.

Growth hormone (GH) is an underappreciated but important regulator of T cell development that can reverse age-related declines in thymopoiesis in rodents. Here, we report findings of a prospective randomized study examining the effects of GH on the immune system of HIV-1-infected adults. GH treatment was associated with increased thymic mass. In addition, GH treatment enhanced thymic output, as measured by both the frequency of T cell receptor rearrangement excision circles in circulating T cells and the numbers of circulating naive and total CD4(+) T cells. These findings provide compelling evidence that GH induces de novo T cell production and may, accordingly, facilitate CD4(+) T cell recovery in HIV-1-infected adults. Further, these randomized, prospective data have shown that thymic involution can be pharmacologically reversed in humans, suggesting that immune-based therapies could be used to enhance thymopoiesis in immunodeficient individuals.

BACKGROUND

Although untreated human immunodeficiency virus (HIV)-infected patients maintaining undetectable plasma HIV RNA levels (elite controllers) have high HIV-specific immune responses, it is unclear whether they experience abnormal levels of T cell activation, potentially contributing to immunodeficiency.

METHODS

We compared percentages of activated (CD38(+)HLA-DR(+)) T cells between 30 elite controllers, 47 HIV-uninfected individuals, 187 HIV-infected individuals with undetectable viremia receiving antiretroviral therapy (antiretroviral therapy suppressed), and 66 untreated HIV-infected individuals with detectable viremia. Because mucosal translocation of bacterial products may contribute to T cell activation in HIV infection, we also measured plasma lipopolysaccharide (LPS) levels.

RESULTS

Although the median CD4(+) cell count in controllers was 727 cells/mm(3), 3 (10%) had CD4(+) cell counts <350 cells/mm(3) and 2 (7%) had acquired immunodeficiency syndrome. Controllers had higher CD4(+) and CD8(+) cell activation levels (P < .001 for both) than HIV-negative subjects and higher CD8(+) cell activation levels than the antiretroviral therapy suppressed (P = .048). In controllers, higher CD4(+) and CD8(+) T cell activation was associated with lower CD4(+) cell counts (P = .009 and P = .047). Controllers had higher LPS levels than HIV-negative subjects (P < .001), and in controllers higher LPS level was associated with higher CD8(+) T cell activation (P = .039).

CONCLUSION

HIV controllers have abnormally high T cell activation levels, which may contribute to progressive CD4(+) T cell loss even without measurable viremia.

Improvements in human immunodeficiency virus (HIV)-associated mortality make it difficult to deny transplantation based upon futility. Outcomes in the current management era are unknown. This is a prospective series of liver or kidney transplant recipients with stable HIV disease. Eleven liver and 18 kidney transplant recipients were followed for a median of 3.4 years (IQR [interquartile range] 2.9-4.9). One- and 3-year liver recipients' survival was 91% and 64%, respectively; kidney recipients' survival was 94%. One- and 3-year liver graft survival was 82% and 64%, respectively; kidney graft survival was 83%. Kidney patient and graft survival were similar to the general transplant population, while liver survival was similar to the older population, based on 1999-2004 transplants in the national database. CD4+ T-cell counts and HIV RNA levels were stable; and there were two opportunistic infections (OI). The 1- and 3-year cumulative incidence (95% confidence intervals [CI]) of rejection episodes for kidney recipients was 52% (28-75%) and 70% (48-92%), respectively. Two-thirds of hepatitis C virus (HCV)-infected patients, but no patient with hepatitis B virus (HBV) infection, recurred. Good transplant and HIV-related outcomes among kidney transplant recipients, and reasonable outcomes among liver recipients suggest that transplantation is an option for selected HIV-infected patients cared for at centers with adequate expertise.

BACKGROUND

The HIV-1 maturation inhibitor, 3-O-(3',3'-dimethylsuccinyl) betulinic acid (bevirimat, PA-457) is a promising drug candidate with 10 nM in vitro antiviral activity against multiple wild-type (WT) and drug-resistant HIV-1 isolates. Bevirimat has a novel mechanism of action, specifically inhibiting cleavage of spacer peptide 1 (SP1) from the C-terminus of capsid which results in defective core condensation.

METHODS AND FINDINGS

Oral administration of bevirimat to HIV-1-infected SCID-hu Thy/Liv mice reduced viral RNA by >2 log(10) and protected immature and mature T cells from virus-mediated depletion. This activity was observed at plasma concentrations that are achievable in humans after oral dosing, and bevirimat was active up to 3 days after inoculation with both WT HIV-1 and an AZT-resistant HIV-1 clinical isolate. Consistent with its mechanism of action, bevirimat caused a dose-dependent inhibition of capsid-SP1 cleavage in HIV-1-infected human thymocytes obtained from these mice. HIV-1 NL4-3 with an alanine-to-valine substitution at the N-terminus of SP1 (SP1/A1V), which is resistant to bevirimat in vitro, was also resistant to bevirimat treatment in the mice, and SP1/AIV had replication and thymocyte kinetics similar to that of WT NL4-3 with no evidence of fitness impairment in in vivo competition assays. Interestingly, protease inhibitor-resistant HIV-1 with impaired capsid-SP1 cleavage was hypersensitive to bevirimat in vitro with a 50% inhibitory concentration 140 times lower than for WT HIV-1.

CONCLUSIONS

These results support further clinical development of this first-in-class maturation inhibitor and confirm the usefulness of the SCID-hu Thy/Liv model for evaluation of in vivo antiretroviral efficacy, drug resistance, and viral fitness.