Kathy Medvik

Human epithelial β-defensins 2 and 3 inhibit HIV-1 replication

Objective: Mechanisms underlying mucosal transmission of HIV-1 are incompletely understood. We describe the anti-HIV-1 activity of human β-defensins (hBD), small cationic molecules that provide protection at mucosal surfaces. Methods and results: HIV-1 induced expression of hBD-2 and -3 mRNA (but not that of hBD-1) 4- to 78-fold, respectively, above baseline in normal human oral epithelial cells. HIV-1 failed to infect these cells, even after 5 days of exposure. Recombinant hBD-1 had no antiviral activity, while rhBD-2 and rhBD-3 showed concentration-dependent inhibition of HIV-1 replication without cellular toxicity. Inhibition was greater against CXCR4-tropic than against the CCR5-tropic HIV-1 isolates. hBD-2 and hBD-3 induced an irreversible effect on virion infectivity, with electron microscopy confirming binding of hBDs to viral particles. Finally, hBD-2 and -3 induced downmodulation of the HIV-1 coreceptor CXCR4 (but not CCR5) in peripheral blood mononuclear cells and T lymphocytic cells as shown by confocal microscopy and flow cytometry. Conclusions: This study shows for the first time that HIV-1 induces β-defensin expression in human oral epithelial cells and that β-defensins block HIV-1 replication via a direct interaction with virions and through modulation of the CXCR4 coreceptor. These properties may be exploited as strategies for mucosal protection against HIV-1 transmission.

IL-7 administration drives T cell-cycle entry and expansion in HIV-1 infection.

Interleukin 7 (IL-7) is a common gamma chain receptor cytokine implicated in thymopoiesis and in peripheral expansion and survival of T lymphocytes. The safety and activity of recombinant human IL-7 (rhIL-7) administration were therefore examined in HIV-infected persons. In this prospective randomized placebo-controlled study, a single subcutaneous dose of rhIL-7 was well tolerated with biologic activity demonstrable at 3 microg/kg and a maximum tolerated dose of 30 microg/kg. Injection site reactions and transient elevations of liver function tests were the most notable side effects. Transient increases in plasma HIV-RNA levels were observed in 6 of 11 IL-7-treated patients. Recombinant hIL-7 induced CD4 and CD8 T cells to enter cell cycle; cell-cycle entry was also confirmed in antigen-specific CD8 T cells. Administration of rhIL-7 led to transient down-regulation of the IL-7 receptor alpha chain (CD127) in both CD4(+) and CD8(+) T cells. Single-dose rhIL-7 increased the numbers of circulating CD4(+) and CD8(+) T cells, predominantly of central memory phenotype. The frequency of CD4(+) T cells with a regulatory T-cell phenotype (CD25(high) CD127(low)) did not change after rhIL-7 administration. Thus, rhIL-7 has a biologic and toxicity profile suggesting a potential for therapeutic trials in HIV infection and other settings of lymphopenia. This clinical trial has been registered at http://www.clinicaltrials.gov under NCT0099671.

The Effect of Raltegravir Intensification on Low-level Residual Viremia in HIV-Infected Patients on Antiretroviral Therapy: A Randomized Controlled Trial

In a double-blind trial, Rajesh Gandhi and colleagues detect no significant reduction in viral load after people with low-level HIV viremia added an integrase inhibitor to their treatment regimen.

Immunologic Failure Despite Suppressive Antiretroviral Therapy Is Related to Activation and Turnover of Memory CD4 Cells

BACKGROUND Failure to normalize CD4(+) T-cell numbers despite effective antiretroviral therapy is an important problem in human immunodeficiency virus (HIV) infection. METHODS To evaluate potential determinants of immune failure in this setting, we performed a comprehensive immunophenotypic characterization of patients with immune failure despite HIV suppression, persons who experienced CD4(+) T-cell restoration with therapy, and healthy controls. RESULTS Profound depletion of all CD4(+) T-cell maturation subsets and depletion of naive CD8(+) T cells was found in immune failure, implying failure of T-cell production/expansion. In immune failure, both CD4(+) and CD8(+) cells were activated but only memory CD4(+) cells were cycling at increased frequency. This may be the consequence of inflammation induced by in vivo exposure to microbial products, as soluble levels of the endotoxin receptor CD14(+) and interleukin 6 were elevated in immune failure. In multivariate analyses, naive T-cell depletion, phenotypic activation (CD38(+) and HLA-DR expression), cycling of memory CD4(+) T cells, and levels of soluble CD14 (sCD14) distinguished immune failure from immune success, even when adjusted for CD4(+) T-cell nadir, age at treatment initiation, and other clinical indices. CONCLUSIONS Immune activation that appears related to exposure to microbial elements distinguishes immune failure from immune success in treated HIV infection.

Nadir CD4+ T-cell count and numbers of CD28+ CD4+ T-cells predict functional responses to immunizations in chronic HIV-1 infection.

Objective: To ascertain whether delaying the initiation of highly active antiretroviral therapy (HAART) compromises functional immune reconstitution in HIV-1 infection in persons who regain ‘normal’ CD4 T-cell counts after suppressive antiretroviral therapies. Design: Prospective open-label study carried out at two University-affiliated HIV-outpatient clinics in the USA. Subjects and methods: Response to immunization was used as a model for in vivo functional immune competence in 29 HIV-1 infected patients with CD4 T-cell counts > 450 × 106cells/l and HIV-RNA < 400 copies/ml for > 12 months after HAART and nine HIV-1 seronegative controls. After immunization with tetanus toxoid, diphtheria-toxoid, and keyhole limpet hemocyanin, immune response scores (IRS) were calculated using postimmunization antibody concentrations, lymphocyte proliferation, and delayed-type hypersensitivity responses to vaccine antigens. Results: Despite normal numbers of circulating CD4 T-cells, the CD4 T-cell nadir before HAART initiation predicted the immune response to immunization (ρ = 0.5; P < 0.005) while current CD4 T-cell count did not. Likewise, CD4 T-lymphocyte expression of the co-stimulatory molecule CD28 was also an independent predictor of response to immunization (ρ = 0.5; P < 0.005). Conclusions: Even among persons who controlled HIV replication and normalized CD4 T-cell counts with HAART, pretreatment CD4 T-cell count and numbers of circulating CD4+CD28+ T-cells at immunization, but not current CD4 T-cell count, predict the ability to respond to vaccination. Delaying the initiation of HAART in chronic HIV-1 infection results in impaired functional immune restoration despite normalization of circulating CD4 T-cell numbers.

Cyclosporin A Provides No Sustained Immunologic Benefit to Persons with Chronic HIV‐1 Infection Starting Suppressive Antiretroviral Therapy: Results of a Randomized, Controlled Trial of the AIDS Clinical Trials Group A5138

BACKGROUND Although the determinants of immune deficiency and immune restoration in chronic human immunodeficiency virus (HIV)-1 infection are not well understood, immune activation has been proposed as being central to the pathogenesis of HIV. METHODS A randomized, controlled trial of cyclosporin A treatment for 2 weeks was performed in persons with chronic HIV-1 infection who were beginning a standardized antiretroviral therapy (ART) regimen. RESULTS Treatment with cyclosporin A provided only a marginal and transient enhancement in circulating T cell restoration that was largely restricted to cells expressing the CCR7 chemokine receptor and that did not persist beyond 2 weeks. CONCLUSIONS Cyclosporin A coadministered for 2 weeks with ART provided no sustained immunologic benefit to persons with chronic HIV-1 infection. If immune activation drives progressive immune deficiency in chronic HIV-1 infection, these activation pathways may not be sensitive to cyclosporin.

Impact of suppression of viral replication by highly active antiretroviral therapy on immune function and phenotype in chronic HIV-1 infection.

We compared immune phenotypes, lymphocyte proliferation (LP), and delayed type hypersensitivity (DTH) responses in 28 male antiretroviral treatment-naive and experienced HIV-1-infected patients, matched pair-wise according to age and CD4+ T-lymphocyte count. Median CD4+ T-lymphocyte counts were 441 cells/microL and 483 cells/microL and median CD4+ T-lymphocyte nadirs were 435 cells/microL and 150 cells/microL in both groups, respectively. Absolute numbers of circulating T-lymphocyte subpopulations and proportions of naive and memory T-lymphocytes were comparable in the two groups. Untreated patients had greater proportions of activated CD4+ (p <.05) and CD8+ (p <.01) T-cells expressing human leukocyte antigen (HLA)DR and CD38 and fewer CD8+ cells expressing CD28 (p <.05). DTH and LP responses were comparable in both groups except for HIVp24, LP responses, and mumps DTH responses, which were of greater magnitude in the group treated with highly active antiretroviral therapy (HAART) (p <.05). Thus, HIV-1-infected patients who experienced substantial increases in CD4+ T-lymphocyte counts after suppression of viral replication on HAART had fewer activated lymphocytes and similar immune function when compared with findings in untreated patients with similar CD4+ T-cell counts. HIV replication has minimal real-time effect on CD4+ T-cell function in response to non-HIV antigens but helper T-cell responses to HIV-gag antigen are impaired during ongoing viral replication and may be restored by antiretroviral therapy.

Baseline Levels of Soluble CD14 and CD16+56− Natural Killer Cells Are Negatively Associated With Response to Interferon/Ribavirin Therapy During HCV-HIV-1 Coinfection

Disease progression of human immunodeficiency virus type 1 (HIV-1) is associated with immune activation. Activation indices are higher during coinfection of hepatitis C virus (HCV) and HIV. The effect of immune activation on interferon α (IFN-α) therapy response is unknown. We evaluated soluble CD14 (sCD14) and natural killer (NK)-cell subsets at baseline, and during pegIFN-α2a/ribavirin therapy in HCV-HIV coinfection. The sCD14 level increased during therapy. Baseline sCD14 positively correlated with baseline HCV level and CD16(+)56(-) NK-cell frequency, and both sCD14 and CD16(+)56(-) NK cells correlated negatively with magnitude of HCV decline. IL28B genotype was associated with therapy response but not sCD14 or CD16(+)56(-) NK frequency. Markers of innate immune activation predict poor host response to IFN-α-based HCV therapy during HCV-HIV coinfection.

Uridine supplementation in the treatment of HIV lipoatrophy: Results of ACTG 5229

Background:Lipoatrophy is prevalent on thymidine nucleoside reverse transcriptase inhibitors (tNRTIs). A pilot trial showed that uridine (NucleomaxX) increased limb fat. Methods:A5229 was a multicenter trial in which HIV-infected individuals with lipoatrophy on tNRTI regimens were randomized to NucleomaxX or placebo. Primary endpoint was change in limb fat from baseline to week 48. The study was powered to detect 400-g difference between arms at week 48. A stratified Wilcoxon rank-sum test was used to assess between-arm differences. Results:The 165 participants were 91% men, 62% white; median age 49 years, CD4 cell count 506 cells/μl, and limb fat 3037 g; 81% had HIV-1 RNA 50 copies/ml or less; 76% were on zidovudine (ZDV). Baseline characteristics were similar between groups. Only 59% completed 48 weeks of treatment; however, only three participants (one on uridine) discontinued due to toxicity (diarrhea). In intent to treat, there was no difference for changes in limb fat between treatments at week 24 or week 48. On as-treated analysis, uridine resulted in an increase in %limb fat vs. placebo (3.4 vs. −0.8%, P = 0.01) at week 24 but not at week 48 (1.8 vs. 3.8%, P = 0.93). Similar results were seen when limiting the analysis to patients with at least 80% adherence. The results were not related to severity of lipoatrophy or type of tNRTI. No changes were found in facial anthropometrics, fasting lipids, trunk fat, CD4 cell count, or HIV RNA. Conclusions:We found a modest transient improvement in limb fat after 24 weeks of uridine. The lack of sustained efficacy at week 48 was not due to changes in adherence or reduction in sample size. Uridine was well tolerated and did not impair virologic control.

Proliferation responses to HIVp24 during antiretroviral therapy do not reflect improved immune phenotype or function.

Objective: To ascertain whether lymphoproliferation (LP) responses to HIVp24 in chronically infected patients treated with antiretroviral therapy (ART) predict an improved cytolytic T-cell phenotype or better in vivo immune function as measured by immunization responses. Methods: HIV-infected patients who started ART during chronic infection and who achieved viral suppression (HIV-RNA < 400 copies/ml for > 12 months) were grouped by the presence of strong [stimulation index (SI) > 10; n = 21] or absent (SI < 3; n = 18) LP to HIV-core antigen. The two groups were compared for functional immune responses to vaccination with diphtheria-toxoid, tetanus-toxoid and keyhole-limpet-hemocyanin, frequency of circulating naive and memory CD4+ and CD8+ T lymphocytes, maturation phenotype and expression of cytolytic molecules on total and HIV-specific CD8+ T cells, and frequency of memory CD4+ T cells with intracellular HIV-mRNA. Group comparisons were analyzed by non-parametric Mann–Whitney tests. Proportions were estimated by Pearson′s χ2 analysis. Results: There were no differences between the groups in immune responses to vaccination or in the numbers or phenotype of circulating T cells. In a subgroup of HLA-A2+ or B8+ patients, HIV-reactive CD8+ T cells in both groups had similar expression of perforin, granzyme A and T-cell maturation markers (CD27, CD28, CCR7, CD62L). However, patients with SI > 10 in response to HIVp24 tended to more often have high levels of circulating CD4+ T cells with intracellular HIV-1 mRNA than did patients with SI < 3. Conclusion: Following long-standing suppression of viral replication on ART, the presence of HIV-1 specific T-helper proliferation responses does not correlate with improved indices of immune phenotype or function but may reflect relatively higher levels of HIV-expression.