Study of patients diagnosed with advanced HIV in the HAART era – OMEGA Cohort

IFN-γ Limits Immunopathogenesis but Delays Fungal Clearance during Pneumocystis Pneumonia

High levels of IFN-γ are produced in the lung during an adaptive immune response to Pneumocystis, but the effects of this prototypical Th1 cytokine on fungal clearance and immunopathogenesis have not been fully defined. Therefore, Pneumocystis-infected immunodeficient mice were immune reconstituted and administered control or anti-IFN-γ neutralizing Ab to determine how IFN-γ regulates the balance between host defense and immune-mediated lung injury. Mice treated with anti-IFN-γ demonstrated an initial worsening of Pneumocystis pneumonia-related immunopathogenesis, with greater weight loss, heightened lung inflammation, and more severe pulmonary function deficits than control mice. However, IFN-γ neutralization also enhanced macrophage phagocytosis of Pneumocystis and accelerated fungal clearance. When anti-IFN-γ-treated mice were also given IL-4 and IL-13 to promote a Th2-biased lung environment, the accelerated fungal clearance was preserved, but the severity of immunopathogenesis was reduced, and a more rapid recovery was observed. A direct suppressive effect of IFN-γ on macrophages was required but was not solely responsible for delayed fungal clearance, suggesting that IFN-γ acts through multiple mechanisms that likely include modulation of both macrophage and Th polarization. Enhanced Pneumocystis clearance in anti-IFN-γ-treated and IFN-γR-deficient mice was associated with significantly elevated IL-17+ CD4+ T cells and IL-17 protein in the lungs. Furthermore, neutralization of IL-17, but not IL-4, signaling blocked the accelerated fungal clearance observed in anti-IFN-γ-treated mice. Together, these data demonstrate that although IFN-γ delays fungal clearance by suppressing the lung Th17 response, it also serves an important regulatory role that limits immunopathogenesis and preserves pulmonary function.

Simplicity and Efficacy of a Once-Daily Antiretroviral Regimen with Didanosine, Lamivudine, and Efavirenz in Naïve Patients: The VESD Study

PURPOSE

Our aim was to analyze the efficacy and safety of didanosine-lamivudine-efavirenz in a cohort of HIV patients starting antiretroviral therapy between January and September 2003.

METHOD

We undertook a prospective, open-label, observational, multicenter study.

RESULTS

163 patients were enrolled. Over a 48-week period, plasma HIV RNA levels declined sharply, with a median decrease at the end of the observation time of >4.62 log copies/mL. The proportion of patients achieving a plasma HIV RNA level below 50 copies/mL was 62.9% (intention-to-treat analysis) at the end of the study period. The mean CD4 cell count increased steadily over time by 199 cells/microL. Antiviral efficacy was similar in patients with a baseline HIV RNA level above or below 100,000 copies/mL. Overall, 57 (34.1%) patients interrupted therapy; 9 due to lack of treatment response, 18 due to adverse side-effects, and 30 patients lost to follow-up or who withdrew their consent. Adherence was very high (90%-95%) and quality of life was good or very good in 69%.

CONCLUSION

The once-daily combination of didanosine-lamivudine-efavirenz resulted in sustained viral suppression and was well-accepted by patients under real-life conditions, even immunosuppressed patients and those with a high viral load. Associated adverse events and virological failures were few.

Immune modulation with sulfasalazine attenuates immunopathogenesis but enhances macrophage-mediated fungal clearance during Pneumocystis pneumonia

Although T cells are critical for host defense against respiratory fungal infections, they also contribute to the immunopathogenesis of Pneumocystis pneumonia (PcP). However, the precise downstream effector mechanisms by which T cells mediate these diverse processes are undefined. In the current study the effects of immune modulation with sulfasalazine were evaluated in a mouse model of PcP-related Immune Reconstitution Inflammatory Syndrome (PcP-IRIS). Recovery of T cell-mediated immunity in Pneumocystis-infected immunodeficient mice restored host defense, but also initiated the marked pulmonary inflammation and severe pulmonary function deficits characteristic of IRIS. Sulfasalazine produced a profound attenuation of IRIS, with the unexpected consequence of accelerated fungal clearance. To determine whether macrophage phagocytosis is an effector mechanism of T cell-mediated Pneumocystis clearance and whether sulfasalazine enhances clearance by altering alveolar macrophage phagocytic activity, a novel multispectral imaging flow cytometer-based method was developed to quantify the phagocytosis of Pneumocystis in vivo. Following immune reconstitution, alveolar macrophages from PcP-IRIS mice exhibited a dramatic increase in their ability to actively phagocytose Pneumocystis. Increased phagocytosis correlated temporally with fungal clearance, and required the presence of CD4(+) T cells. Sulfasalazine accelerated the onset of the CD4(+) T cell-dependent alveolar macrophage phagocytic response in PcP-IRIS mice, resulting in enhanced fungal clearance. Furthermore, sulfasalazine promoted a TH2-polarized cytokine environment in the lung, and sulfasalazine-enhanced phagocytosis of Pneumocystis was associated with an alternatively activated alveolar macrophage phenotype. These results provide evidence that macrophage phagocytosis is an important in vivo effector mechanism for T cell-mediated Pneumocystis clearance, and that macrophage phenotype can be altered to enhance phagocytosis without exacerbating inflammation. Immune modulation can diminish pulmonary inflammation while preserving host defense, and has therapeutic potential for the treatment of PcP-related immunopathogenesis.

A longitudinal study of the changes in body fat and metabolic parameters in a South African population of HIV-positive patients receiving an antiretroviral therapeutic regimen containing stavudine

The aim of this study was to determine the patterns of change in body fat and metabolic parameters in a South African cohort on a first line ART regimen containing stavudine. Fasting lipogram, blood glucose and insulin levels, CD4 cell count, viral load, BMI, waist-to-hip ratio (WHR), and skinfold thickness at the triceps, scapula, and iliac crest were measured before starting ART in 42 (27 female) subjects. Repeat measurements were performed at four monthly intervals for 2 years. Lipodystrophy was diagnosed using patient perception and assessment by a physician. At baseline, subjects who went on to develop lipodystrophy (LD group) were fatter and had higher skinfold thickness at all three sites and higher insulin levels than subjects who never developed lipodystrophy (NLD group). The WHR increased to a greater extent while hip circumference and tricep skinfolds fell more significantly in the LD than NLD group. Triglyceride and cholesterol levels increased significantly in both groups while lactate and glucose levels increased more and insulin levels increased less in the LD than the NLD group. Neither viral load nor CD4 count differed between the groups during the study. Viral load correlated positively with insulin levels at baseline. Thus, lipodystrophy in the South African population is characterized by a higher BMI before initiation of ART and lipoatrophy of the arms and hips, lipohypertrophy of the waist, and increased lactate production. When compared to the NLD group, the LD subjects display attenuated insulin secretory output in response to a higher weight gain.

Concurrent HIV/AIDS diagnosis increases the risk of short-term HIV-related death among persons newly diagnosed with AIDS, 2002-2005

Despite the overall effectiveness and availability of highly active antiretroviral therapy (HAART), 1500 HIV-related deaths still occur annually in New York City. In considering ways to further reduce deaths, we assessed the contribution of concurrent HIV/AIDS diagnosis to HIV-related mortality in New York City among persons newly diagnosed with AIDS. We used Cox regression to conduct a retrospective cohort analysis of HIV-related mortality among 15,211 residents age 13+ reported with AIDS to the population-based HIV/AIDS registry between January 2002 and June 2005. Concurrent HIV/AIDS diagnosis was defined as a diagnosis of AIDS occurring within 1 month of initial diagnosis of HIV. HIV-related mortality was 20.2% among persons diagnosed concurrently and 12.2% among those diagnosed nonconcurrently (p < 0.0001). Concurrent HIV/AIDS was associated with more than twice the risk of HIV-related death within the 4 months after diagnosis (hazard ratio [HR] 2.27, 95% confidence interval [CI] 1.94-2.65) but no increased risk thereafter (HR 1.12, 95% CI 0.77-1.61). Other significant predictors of death included injection drug use and birth in the Caribbean or Latin America. After 4 years 11.9% of all HIV-related deaths were attributable to a concurrent HIV/AIDS diagnosis. Public health initiatives that facilitate early diagnosis of HIV may reduce HIV-related mortality by giving people the opportunity to initiate care and begin treatment with HAART before immunosuppression places them at risk for opportunistic illness and death.