Immune reconstitution

The next generation of HIV/AIDS drugs: novel and developmental antiHIV drugs and targets

There are presently 42 million people worldwide living with HIV/AIDS, the majority of which have limited access to antiretrovirals. Even if worldwide penetration was possible, our current chemotherapeutic strategies still suffer from issues of cost, patient compliance, deleterious acute and chronic side effects, emerging single and multidrug resistance, and generalized treatment and economic issues. Even our best antiretroviral therapeutic strategy, highly active antiretroviral therapy (HAART), falls short of completely suppressing HIV replication. Therefore, expansion of current therapeutic options by discovering new antiretrovirals and targets will be critical in the coming years. This review addresses the current status of reverse transcriptase and protease inhibitor development, and summarizes the progress in emerging classes of HIV inhibitors, including entry (T-20, T-1249), coreceptor (SCH-C, SCH-D), integrase (beta-Diketos) and p7 nucleocapsid Zn finger inhibitors (thioesters and PATEs). In addition, the processes of virus entry, PIC transport to the nucleus, HIV interaction with nuclear pores, Tat function, Rev function and virus budding (Tsg101 and ubiquitination) are examined, and proof of concept inhibitors and potential antiviral targets discussed.

Failure of highly active antiretroviral therapy in reconstituting immune response to Clostridium tetani vaccine in aged AIDS patients

The purpose of this study was to evaluate the impact of age on tetanus-specific immune response in successfully highly active antiretroviral therapy-treated AIDS patients, using healthy age-matched individuals as controls. Whole Peripheral blood mononuclear cells or CD8(+) cell-depleted peripheral blood mononuclear cells from previously tetanus toxoid (TT)-immunized individuals were activated with TT plus IL-2, and cell proliferation, cytokine production, and in vitro HIV-1 replication were measured. The in vivo magnitude of the humoral immune response was also assessed by antibody measurements. Our results showed that, compared with other groups, both in vitro TT-specific lymphoproliferation and serum antibody concentration were lower in older AIDS patients. Although the IL-1beta and tumour necrosis factor alpha (TNF-alpha) production were higher in cultures from aged HIV-1-infected patients, a dramatic damage on the interferon gamma (IFN-gamma) release was observed, when compared with younger patients. CD8(+) T lymphocytes depletion reduced IL-1beta and TNF-alpha release in the older groups, however, it did not significantly alter their IFN-gamma production. Furthermore, the neutralization of endogenous IL-10 did not change the IFN-gamma deficiency in older AIDS patients. Finally, the lower cellular immune response in this patient group was not related to in vitro HIV-1 replication. The results suggest that successfully highly active antiretroviral therapy-treated aged AIDS patients do not reconstitute the immune response to TT, making them probably more susceptible to tetanus even after vaccination.

Anti-CD3/28 mediated expansion of macaque CD4+ T cells is polyclonal and provides extended survival after adoptive transfer

BACKGROUND

Our lab has previously shown that adoptive transfer of in vitro expanded autologous purified polyclonal CD4(+) T cells using anti-CD3/CD28 coated beads induced antiviral responses capable of controlling simian immunodeficiency virus (SIV) replication in vivo.

RESULTS

Expansion on anti-CD3/28 coated beads was found to induce a true polyclonal expansion as CFSE labeled cells uniformly showed dilution of the dye over several days of culture, in contrast to aliquots of the same cells subjected to mitogen stimulation. Of interest was the finding that CD4(+) T cells collected before and during early chronic SIV infection or AIDS stage did not show any or only modest differences in proliferative response or expansion kinetics. The reason for such excellent expansion properties was analyzed by the quantitation of telomerase activity in aliquots of expanding CD4(+) T cells from sample collected at various times post-infection. First, anti-CD3/28 expanded CD4(+) T cells exhibited telomerase levels 2- to 20-fold higher than the starting population of CD4(+) T cells. Moreover, while telomerase activity in ex vivo tested CD4(+) T cells was found to decrease following SIV infection and disease progression, anti-CD3/28 expansion appeared to restore significant levels of telomerase activity as no difference was noted in telomerase expression between CD4(+) T cells expanded from samples collected before or during the chronic SIV infection. When such expanded and CFSE labeled T cells were autologously transferred to monkeys, evidence for extended survival in vivo was provided as CFSE labeled cells were detected to relatively high levels in blood and spleen at 1 week post-infection.

CONCLUSION

In summary, the data suggest that anti-CD3/28 mediated expansion of CD4(+) T cells retains its immunotherapeutic potential not only during the early stages of lentiviral infection but also at more advanced stages of disease.

Interleukin-10-secreting CD4 cells from aged patients with AIDS decrease in-vitro HIV replication and tumour necrosis factor alpha production

OBJECTIVE

To evaluate the impact of age on the proliferative response, cytokine profile and viral kinetics in AIDS patients treated successfully with antiretroviral drugs.

METHODS

Peripheral blood mononuclear cells (PBMC), CD4 cell-depleted PBMC or CD4 T cells from young adult and aged HIV-1-infected patients were activated in vitro with anti-CD3 with or without interleukin (IL)-2. Lymphoproliferation and cytokines were measured after 3 days and in-vitro HIV-1 replication after 7 days.

RESULTS

Both lymphoproliferation and cytokine [IL-1beta, tumour necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma)] secretion were higher in younger than in older AIDS patients. In cultures of cells derived from aged patients and activated by anti-CD3, IFN-gamma production was severely damage and IL-10 production was much higher. Although IL-2 addition to activated PBMC elevated IFN-gamma secretion, IL-10 production remained elevated in the aged group. The depletion of CD4 T lymphocytes from these cultures dramatically reduced released IL-10 in the older group but did not alter significantly IFN-gamma production. Interestingly, higher IL-10 levels produced by CD4 T cells were related to lower in-vitro HIV-1 replication, and the blockade of this cytokine by anti-IL-10 monoclonal antibody enhanced virus replication. This effect may be correlated with elevated TNF-alpha secretion. Finally, impaired IFN-gamma secretion detected in activated CD4 T cells obtained from aged patients was not directly correlated with high IL-10 production.

CONCLUSIONS

Elevated IL-10 production by aged AIDS patients contributed considerably to control of HIV replication and to inhibition of TNF-alpha secretion but not to the reduced IFN-gamma production.

Cellular immune response to pulmonary infections in HIV-infected individuals hospitalized with diverse grades of immunosuppression

The lymphocyte profile of 521 HIV-infected subjects hospitalized at Jackson Memorial (2001-2002) was compared across main respiratory diseases. Study data included medical history and all laboratory evaluations performed during hospitalization. Community-acquired pneumonias (CAP, 52%), Pneumocystis jiroveci pneumonia (PCP, 24%), tuberculosis (TB, 9%) and non-tuberculous mycobacterial diseases (NTM, 12%) were the most frequent causes of admission. Patients hospitalized with PCP and NTM exhibited the lowest CD4 counts (P=0.003). PCP patients had the highest B-cell percentages (P=0.04). CAP patients had the highest CD8 and CD4 percentages and the lowest percentage of Natural Killer (NK) cells and viral burdens. TB patients exhibited the lowest NK-cell (11.4+/-6.3) and B-cell percentages (13.6+/-12) and the highest CD8 (59+/-14) percentage. NTM patients, in contrast, had the highest NK-cell percentages of the groups (19.1+/-11.6, P=0.01). Additionally, immune responses associated with respiratory pathogens differed in HIV-infected patients with CD4(+) cells above and below 200 counts.

Increased risk of Pneumocystis carinii and community-acquired pneumonia with tobacco use in HIV disease

OBJECTIVES

Tobacco smoking-related diseases continue to be of great health concern for the public, in general, and may be particularly deleterious for immunosuppressed HIV-positive individuals, who exhibit widespread tobacco use.

METHODS

A total of 521 HIV-infected subjects consecutively admitted to Jackson Memorial Hospital between 2001-2002 were enrolled in the study. Research data included a medical history, details of tobacco and illicit drug use and complete computerized hospital information. Blood was drawn to obtain T lymphocyte profiles and viral load levels. Statistical analysis methods included Pearson, Student's t- and Chi-square tests and SAS Proc CATMOD.

RESULTS

Tobacco use was prevalent, with 65% of the 521 HIV-positive hospitalized patients being current smokers. Overall, current tobacco users reported smoking an average of 15+/-13 cigarettes per day for an average of 15+/-14 years, with 40% smoking more than one pack per day. Pulmonary infections accounted for 49% of the total hospital admissions: 52% bacterial pneumonias, 24% Pneumocystis carinii pneumonia (PCP), 12% non-tuberculous mycobacterial diseases (NTM), 11% tuberculosis and 1% bronchitis. Many of the respiratory patients (46%) had been on highly active antiretroviral therapy (HAART) for over six months and 42% had received PCP and/or NTM prophylaxis. After matching the cases by HAART and CDC stage, the hazardous risk of being hospitalized with a respiratory infection was significantly higher for smokers than non-smokers (95% CI 1.33-2.83; p=0.003). Respiratory infections were noted in (37%) of the HAART-treated patients, and most (67%) occurred in smokers. CATMOD analyses controlling for HAART, viral load and CD4, indicated that HIV-infected smokers were three times more likely to be hospitalized with PCP and twice as likely to be hospitalized with community-acquired pneumonia than non-smokers, with increased risk related to the number of cigarettes/day in a dose-dependent manner.

CONCLUSIONS

Tobacco use, which is widespread among HIV-infected subjects, increases the risk of pulmonary diseases, particularly PCP and CAP, two respiratory infections with high prevalence and morbidity risks even in the era of HAART.

SEN virus seroprevalence in HIV positive patients: association with immunosuppression and HIV-replication

BACKGROUND

Patients infected with HIV are often co-infected with other viruses. SEN virus (SENV) was isolated from a HIV positive patient with intravenous drug use and post-transfusion hepatitis. SENV strains D and H seem to be relevant for the development of post-transfusion hepatitis. We compared the prevalence of SENV strains D and H and the viral load of SENV H in HIV-infected patients with healthy blood donors. The results were correlated with clinical markers such as HIV stage, CD4 cell count, HIV-RNA positivity, HAART or the transmission mode in HIV infected individuals.

OBJECTIVES

Blood samples of 143 HIV-positive patients were analysed and compared with a control group of 122 healthy blood donors. SENV D and -H was detected by PCR.

RESULTS

SENV was detectable in 15.4% (22/143) of HIV-positive patients compared to 10.4% (12/122) in the control group (P=0.18). SENV H DNA-levels were significantly higher in HIV-positive patients (P=0.01). The prevalence in patients with CD4 cells less than 200/mm(3) was 31% (13/42), compared to 12.3% (8/65) in cases with CD4 cells between 200 and 500/mm(3), and 2.8% in cases with CD4 cells above 500/mm(3) (P=0.002 for CD4 cells <200 versus CD4 cells >200, P=0.031 for CD4 cells <500 versus CD4 cells >500). Prevalence of these strains was not significantly influenced by CDC stages. SENV was detected significantly more frequent in patients with detectable HIV-RNA (P=0.005). Patients undergoing HAART were significantly less frequent positive for SENV D or -H (P=0.029) than patients without HAART. In a multivariate analysis using a logistic regression model HIV-RNA positivity and CD4 cell count were identified as independent factors for SENV prevalence.

CONCLUSION

SENV (D and H) prevalence is not significantly higher in HIV-positive patients in comparison to healthy blood donors. SENV prevalence depends on CD4 cell count and HIV-RNA.