Impact of CMV therapy with valganciclovir on immune activation and the HIV viral load in semen and blood: an observational clinical study.

BACKGROUND: The HIV RNA viral load (VL) in vaginal secretions and semen is an independent predictor of HIV transmission. Blood VL is associated with semen VL, and local mucosal factors, such as semen cytomegalovirus (CMV) reactivation, may play an important role. METHODS: Twenty-one HIV-CMV-coinfected, antiretroviral-naive men received 900 mg of oral valganciclovir once daily for 2 weeks in an open-label study. Blood and semen were collected at baseline, after 2 weeks of valganciclovir, and 2 months after therapy completion. The primary end point was change in semen HIV levels at 2 weeks, and the secondary end points were change in semen HIV VL at 2 months and change in semen CMV levels. RESULTS: The HIV VLs fell significantly at 2 weeks in semen (median 3.44-3.02 log10 copies/mL, P = 0.02) and blood (median 3.61-3.10 log10 copies/mL, P < 0.01) and returned to baseline after therapy completion (median 3.24 and 3.71 log10 copies/mL in semen and blood, respectively). Semen CMV levels also fell on treatment (median 2.13-1.62 log10 copies/mL, P < 0.01) and continued to fall after therapy completion (median 0.91 log10 copies/mL at week 8, P < 0.001 vs. baseline). The reduced semen CMV VL was associated with decreased semen T-cell activation and enhanced CMV-specific T-cell responses in blood; changes in the semen HIV VL were not associated with immune parameters. CONCLUSIONS: Although valganciclovir therapy was associated with reduced HIV and semen CMV levels, these results suggest that the reduced HIV VL was a direct drug effect rather than a CMV antiviral effect or CMV-associated immune alterations.

Increased HIV-specific CD8+ T-cell cytotoxic potential in HIV elite controllers is associated with T-bet expression.

Recent data suggest that CD8+ T-cell effector activity is an important component in the control of HIV replication in elite controllers (ECs). One critical element of CD8+ T-cell effector function and differentiation is the T-box transcription factor T-bet. In the present study, we assessed T-bet expression, together with the effector proteins perforin, granzyme A (Grz A), granzyme B (Grz B), and granulysin, in HIV-specific CD8+ T cells from ECs (n = 20), chronically infected progressors (CPs; n = 18), and highly active antiretroviral therapy (HAART)-suppressed individuals (n = 19). Compared with the other cohort groups, HIV-specific CD8+ T cells among ECs demonstrated a superior ability to express perforin and Grz B, but with no detectable difference in the levels of Grz A or granulysin. We also observed higher levels of T-bet in HIV-specific CD8+ T cells from ECs, with an ensuing positive correlation between T-bet and levels of both perforin and Grz B. Moreover, HIV-specific CD8+ T cells in ECs up-regulated T-bet to a greater extent than CPs after in vitro expansion, with concomitant up-regulation of perforin and Grz B. These results suggest that T-bet may play an important role in driving effector function, and its modulation may lead to enhanced effector activity against HIV.

Perforin expression directly ex vivo by HIV-specific CD8 T-cells is a correlate of HIV elite control.

Many immune correlates of CD8(+) T-cell-mediated control of HIV replication, including polyfunctionality, proliferative ability, and inhibitory receptor expression, have been discovered. However, no functional correlates using ex vivo cells have been identified with the known ability to cause the direct elimination of HIV-infected cells. We have recently discovered the ability of human CD8(+) T-cells to rapidly upregulate perforin--an essential molecule for cell-mediated cytotoxicity--following antigen-specific stimulation. Here, we examined perforin expression capability in a large cross-sectional cohort of chronically HIV-infected individuals with varying levels of viral load: elite controllers (n = 35), viremic controllers (n = 29), chronic progressors (n = 27), and viremic nonprogressors (n = 6). Using polychromatic flow cytometry and standard intracellular cytokine staining assays, we measured perforin upregulation, cytokine production, and degranulation following stimulation with overlapping peptide pools encompassing all proteins of HIV. We observed that HIV-specific CD8(+) T-cells from elite controllers consistently display an enhanced ability to express perforin directly ex vivo compared to all other groups. This ability is not restricted to protective HLA-B haplotypes, does not require proliferation or the addition of exogenous factors, is not restored by HAART, and primarily originates from effector CD8(+) T-cells with otherwise limited functional capability. Notably, we found an inverse relationship between HIV-specific perforin expression and viral load. Thus, the capability of HIV-specific CD8(+) T-cells to rapidly express perforin defines a novel correlate of control in HIV infection.

Relative HIV resistance in kenyan sex workers is not due to an altered prevalence or mucosal immune impact of herpes simplex virus type 2 infection.

Chronic infection by herpes simplex virus type 2 (HSV-2) increases HIV susceptibility, perhaps due to HSV-2-associated increases in activated mucosal immune cells. A small number of Kenyan female sex workers (FSWs) exhibit relative HIV resistance. We examined whether relative HIV resistance was related to differences in the prevalence or mucosal immune impact of HSV-2. Participants were recruited from an open cohort of HIV-uninfected FSWs in Nairobi, Kenya. Women who had been practicing sex work in the cohort for >or=3 years without acquiring HIV were defined as relatively HIV resistant. HSV-2 diagnostics were performed, and cervical immune cell subsets were examined by flow cytometry in a subset of participants. The study population comprised 139 HIV-uninfected FSWs. HSV-2 seroprevalence was actually higher in FSWs meeting criteria for relative HIV resistance than in non-resistant FSWs (75/80, 94% vs 46/59, 78%; LR = 7.5; P = 0.006), likely due to the increased age and longer duration of sex work in the resistant subgroup. Late HIV acquisition was not associated with recent HSV-2 infection, and HSV-2 associated increases in HIV-susceptible cervical immune cell populations were similar in both groups. Relative HIV resistance in Kenyan FSWs was not due to a reduced prevalence or mucosal immune impact of HSV-2 infection.

Mucosal Neisseria gonorrhoeae coinfection during HIV acquisition is associated with enhanced systemic HIV-specific CD8 T-cell responses.

BACKGROUND: The host immune response against mucosally acquired pathogens may be influenced by the mucosal immune milieu during acquisition. As Neisseria gonorrhoeae can impair dendritic cell and T-cell immune function, we hypothesized that coinfection during HIV acquisition would impair subsequent systemic T-cell responses. METHODS: Monthly screening for sexually transmitted infections was performed in high risk, HIV seronegative Kenyan female sex workers as part of an HIV prevention trial. Early HIV-specific CD8 T-cell responses and subsequent HIV viral load set point were assayed in participants acquiring HIV, and were correlated with the presence of prior genital infections during HIV acquisition. RESULTS: Thirty-five participants acquired HIV during follow-up, and 16 out of 35 (46%) had a classical sexually transmitted infection at the time of acquisition. N. gonorrhoeae coinfection was present during HIV acquisition in 6 out of 35 (17%), and was associated with an increased breadth and magnitude of systemic HIV-specific CD8 T-cell responses, using both interferon-gamma gamma and MIP-1 beta as an output. No other genital infections were associated with differences in HIV-specific CD8 T-cell response, and neither N. gonorrhoeae nor other genital infections were associated with differences in HIV plasma viral load at set point. CONCLUSION: Unexpectedly, genital N. gonorrhoeae infection during heterosexual HIV acquisition was associated with substantially enhanced HIV-specific CD8 T-cell responses, although not with differences in HIV viral load set point. This may have implications for the development of mucosal HIV vaccines and adjuvants.

Coinfection with herpes simplex virus type 2 is associated with reduced HIV-specific T cell responses and systemic immune activation.

BACKGROUND: Chronic coinfection with herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV) has been associated with an increased HIV viral load and more rapid disease progression, perhaps related to HSV-2-associated alterations in host immunity. METHODS: Studies were nested within (1) a cross-sectional study of men coinfected with HIV and HSV-2 and (2) women not infected with HIV, both before and after HSV-2 acquisition. HSV-2 infection status was determined by ELISA. HIV-specific CD8(+) T cell epitopes were mapped, and proliferation of HIV-specific cells was also assessed. Systemic inflammatory and regulatory T cell populations were assayed by flow cytometry. RESULTS: The breadth of both the HIV-specific CD8(+) T cell interferon-gamma and proliferative responses was reduced in participants coinfected with HIV and HSV-2, independent of the HIV plasma viral load and CD4(+) T cell count, and the magnitude of the responses was also reduced. HSV-2 infection in this group was associated with increased T cell CD38 expression but not with differences in the proportion of CD4(+) FoxP3(+) regulatory T cells. However, in women not infected with HIV, acquisition of HSV-2 was associated with an increase in the proportion of regulatory T cells. CONCLUSIONS: HSV-2 coinfection was associated with reduced HIV-specific T cell responses and systemic inflammation. The immune effects of HSV-2 may underlie the negative impact that this coinfection has on the clinical course of HIV infection.

Activated protein C in sepsis and beyond: update 2006.

Activated protein C (APC), a plasma serine protease, is best known for its ability to inhibit blood clot formation. APC acts as an anticoagulant by degrading coagulation cofactors Va and VIIIa, thereby attenuating the coagulation cascade. Over the past 15 years, impressive research advances have provided novel insights into the diverse biological activities of this molecule. APC is now viewed not only as an anticoagulant but also as a signaling molecule that provides a pivotal link between the pathways of coagulation, inflammation, apoptosis, and vascular permeability. The protective effect of APC supplementation in patients with severe sepsis likely reflects the ability of APC to modulate multiple pathways implicated in sepsis pathophysiology. This review attempts to summarize key studies that support the therapeutic potential of APC in conditions beyond sepsis such as stroke, ischemia-reperfusion injury, lung injury, asthma, pancreatitis, wound healing, and angiogenesis. A comprehensive PUBMED literature review up to May 2006 was conducted.

Effects of the chemotherapeutic agent doxorubicin on the protein C anticoagulant pathway.

Although chemotherapy treatment is associated with an increased risk of thrombosis, the pathogenic mechanisms for the thrombogenic effect of chemotherapeutic drugs are poorly understood. We hypothesize that exposure of vascular endothelial cells to chemotherapeutic agents results in the loss of a thromboresistant phenotype. In this study, we examined the effects of the chemotherapeutic agent doxorubicin on the endothelium-based protein C anticoagulant pathway. The endothelial cell protein C receptor (EPCR) and thrombomodulin are two endothelial cell surface receptors required for the conversion of zymogen protein C to the anticoagulant enzyme activated protein C. Exposure of human umbilical vein endothelial cells (HUVEC) to doxorubicin resulted in a dose- and time-dependent decrease in cell surface EPCR levels. This decrease occurred as a result of receptor shedding as well as from a down-regulation in EPCR mRNA levels. In contrast, doxorubicin treatment of HUVECs resulted in a dose- and time-dependent increase in cell surface thrombomodulin attributed to an up-regulation of thrombomodulin mRNA levels. The net effect of the doxorubicin-induced changes in EPCR and thrombomodulin levels was a decrease in the capacity of HUVECs to convert protein C to activated protein C. Preliminary studies suggest that doxorubicin free radical metabolites mediate the doxorubicin-induced changes in EPCR expression but not those of thrombomodulin expression. In summary, these results suggest that doxorubicin alters the hemostatic balance of endothelial cells by down-regulating the endothelium-based protein C anticoagulant pathway.