Peter Erb

Clinical progression, survival, and immune recovery during antiretroviral therapy in patients with HIV-1 and hepatitis C virus coinfection: the Swiss HIV Cohort Study

BACKGROUND Hepatitis C virus (HCV) infection is highly prevalent among HIV-1-infected individuals, but its contribution to the morbidity and mortality of coinfected patients who receive potent antiretroviral therapy is controversial. We used data from the ongoing Swiss HIV Cohort Study to analyse clinical progression of HIV-1, and the virological and immunological response to potent antiretroviral therapy in HIV-1-infected patients with or without concurrent HCV infection. METHODS We analysed prospective data on survival, clinical disease progression, suppression of HIV-1 replication, CD4-cell recovery, and frequency of changes in antiretroviral therapy according to HCV status in 3111 patients starting potent antiretroviral therapy. RESULTS 1157 patients (37.2%) were coinfected with HCV, 1015 of whom (87.7%) had a history of intravenous drug use. In multivariate Coxs regression, the probability of progression to a new AIDS-defining clinical event or to death was independently associated with HCV seropositivity (hazard ratio 1.7 [95% CI 1.26-2.30]), and with active intravenous drug use (1.38 [1.02-1.88]). Virological response to antiretroviral therapy and the probability of treatment change were not associated with HCV serostatus. In contrast, HCV seropositivity was associated with a smaller CD4-cell recovery (hazard ratio for a CD4-cell count increase of at least 50 cells/microL=0.79 [0.72-0.87]). INTERPRETATION HCV and active intravenous drug use could be important factors in the morbidity and mortality among HIV-1-infected patients, possibly through impaired CD4-cell recovery in HCV seropositive patients receiving potent antiretroviral therapy. These findings are relevant for decisions about optimum timing for HCV treatment in the setting of HIV infection.

Transmission of Human Herpesvirus 8 Infection from Renal-Transplant Donors to Recipients

BACKGROUND Human herpesvirus 8 (HHV-8) has been detected in all forms of Kaposis sarcoma, including transplantation-associated Kaposis sarcoma. To investigate the possibility of transmission of HHV-8 through allografts, we measured the seroprevalence of HHV-8 before and after renal transplantation. METHODS Using an enzyme-linked immunosorbent assay with the recombinant HHV-8 protein orf 65.2, we analyzed serum samples from 220 renal-transplant recipients for the presence of antibodies to HHV-8 on the day of transplantation and one year later. Positive results were confirmed by an indirect immunofluorescence assay that detects antibodies to latent antigen and by Western blotting. Follow-up lasted at least four years. RESULTS The seroprevalence of HHV-8 in graft recipients increased from 6.4 percent on the day of transplantation to 17.7 percent one year after transplantation. Seroconversion occurred within the first year after transplantation in 25 patients, and Kaposis sarcoma developed in 2 of them within 26 months after transplantation. Sequential serum samples were obtained from 10 of the patients with seroconversion, and in 8 of these patients, IgM antibodies to HHV-8 appeared within three months after transplantation. In the case of six patients who seroconverted, serum samples from the donors were available, and five (83 percent) tested positive for HHV-8. In a control group of eight patients who were seronegative at the time of transplantation and who received allografts from HHV-8-negative donors, none seroconverted within the year after transplantation. CONCLUSIONS HHV-8 is transmitted through renal allografts and is a risk factor for transplantation-associated Kaposis sarcoma.

Mechanism and biological significance of CD4-mediated cytotoxicity

It is now well established that CD4+ T cells can express cytotoxic activity. This type of cell-mediated cytotoxicity is associated with the Th1-, but not with the Th2-phenotype. While the activation of CD4+ CTL is MHC class II-restricted, the effector phase, i.e. the target cell killing is unrestricted and antigen non-specific. In analogy to CD8+ CTL, CD4-mediated target cell death is by DNA fragmentation. However, the molecular mechanism of killing differs from CD8-mediated lysis. Thus, CD4+ CTL preferentially lyse their targets via Fas-Fas ligand interaction, whereas the major cytotoxic effect of CD8+ CTL is by granule exocytosis, i.e. perforin and granzymes. Although CD8+ CTL can also express the FasL, their lytic activity through interaction with Fas is of less importance. Likewise, some CD4+ CTL may also kill by perforin/granzymes activity, but this pathway is of minor significance. The aims of CD8- or CD4-mediated lysis are also different. Thus, the major task of CD8+ CTL which recognize and kill their targets in the context of MHC class I molecules, is the lysis of virally infected cells and battling against tumor cells. CD4+ CTL, on the other hand, have an immunomodulatory role. Thus, they preferentially eliminate activated MHC class II-positive cells, i.e. APC, be they monocytes/macrophages, B cells or T cells. They may lyse these cells in order to prevent an overreaction of the ongoing immune response or in order to remove potentially hazardous cells upon completion of the immune response. The Fas-FasL pathway is particularly suitable for this task as myeloid or lymphoid cells express Fas only if activated, while FasL is preferentially expressed on activated CD4+ Th1 cells. Moreover, activated T cells eliminate themselves by the Fas-mediated pathway. Whether this happens by fratricide only, or also by suicide or both is open. Moreover, CD4+ CTL are particularly suitable for killing tumor cells as well, as they are efficient effectors in bystander lysis in contrast to CD8+ CTL. On the other hand, the non-specific killing via Fas-FasL interaction, which is an important reason for the bystander lysis, may have unwanted effects in that cells which should not be eliminated could be killed. Such reactions affecting various organs and cells, e.g. the liver, thyroid or islet cells of the pancreas could be an explanation for certain autoimmune diseases.

Antiretroviral Therapy Reduces Markers of Endothelial and Coagulation Activation in Patients Infected with Human Immunodeficiency Virus Type 1

We investigated the effect of antiretroviral therapy on vascular activation in 41 human immunodeficiency (HIV)--infected patients receiving a regimen that included either at least 1 protease inhibitor (PI; n = 21) or a nonnucleoside reverse-transcriptase inhibitor (NNRTI; n = 20). A control group of 21 healthy subjects was included for comparison. Levels of endothelial markers (soluble vascular cell adhesion molecule [sVCAM]--1, soluble intercellular adhesion molecule--1, and von Willebrand factor) were higher in HIV-infected persons before treatment than in control subjects and decreased significantly after 5--13 months of treatment. Levels of sVCAM-1 and von Willebrand factor correlated significantly with initial virus load. d-dimer concentrations also decreased significantly after initiation of treatment. PI- and NNRTI-containing regimens had similar effects. Therapy did not reduce levels of the soluble platelet (sP) activation markers sP-selectin and CD40 ligand. The inhibition of markers of vascular activation may counterbalance sequelae of therapy-induced dyslipidemia and potentially prevent development of atherosclerosis in HIV-infected patients.

The Fas receptor in HIV infection : expression on peripheral blood lymphocytes and role in the depletion of T cells

ObjectiveTo analyse the role of the apoptosis-inducing Fas receptor in the depletion of CD4+ and CD8+ T cells in HIV-infected individuals. MethodsPeripheral blood lymphocytes (PBL) obtained from HIV-infected subjects of all 1993 Centers for Disease Control and Prevention (CDC) stages and from non-infected controls were examined. A two-colour cytofluorometry was employed using monoclonal antibodies against Fas receptor (CD95) in combination with the surface markers CD4, CD8, CD28, CD26 and CD45RO. CD4+ and CD8+ T-cell-enriched PBL were used as target cells to assess their susceptibility to lysis by CD4+ cytotoxic T lymphocytes (CTL) which kill via the Fas pathway. Results: Fas+ PBL are more elevated in HIV-infected individuals than in HIV-negative controls and increase significantly from CDC stages A to C. Whereas Fas+CD4+ and Fas-CD4+ T-cell populations decline in parallel with the progression of HIV infection, the Fas+CD8+, but not of the Fas-CD8+ fraction, significantly increases. The Fas+CD8+ lymphocytes are susceptible to Fas-mediated lysis as they are efficiently killed by Fas-ligand+CD4+ CTL. ConclusionThe Fas receptor may contribute, but not as a unique cause, to the decline of CD4+ T cells in HIV-infected individuals. This and the significant increase of the number of Fas+CD8+ T cells indicates that Fas-mediated immune regulation is disturbed.

Regression of basal cell carcinoma by intralesional interferon-alpha treatment is mediated by CD95 (Apo-1/Fas)-CD95 ligand-induced suicide.

Basal cell carcinoma (BCC) is the most common skin cancer in humans, and although metastasis rarely occurs, the tumor cells are nevertheless able to invade and destroy the surrounding tissue. Intralesional injection of IFN-alpha has been found to be highly effective in inducing BCC regression by an unknown mechanism. We show that in untreated patients, BCC cells express CD95 ligand, but not the receptor, which may allow tumor expansion by averting the attack of activated CD95 receptor-positive lymphoid effector cells. The CD95 ligand of BCC cells is functional as CD95-positive cells incubated on BCC cryosections become apoptotic and are lysed. In IFN-alpha-treated patients BCC cells express not only CD95 ligand but also CD95 receptor, whereas the peritumoral infiltrate that mainly consists of CD4+ T cells predominantly contains CD95 receptor and only few CD95 ligand-positive cells. Thus, in treated patients BCC most likely regresses by committing suicide through apoptosis induction via CD95 receptor-CD95 ligand interaction.

Inhibition of T helper 2-type responses, IgE production and eosinophilia by synthetic lipopeptides

In allergy and asthma, the fine balance between the T helper (Th) 1, Th2 and T regulatory cytokine responses appears to be shifted towards Th2. Here, we report that synthetic lipopeptides which contain the typical lipid part of the lipoprotein of gram‐negative bacteria stimulate a distinct regulatory cytokine pattern and inhibit several Th2 cell‐related phenomena. The most potent analogue of synthetic lipopeptides, lipopeptide CGP 40774 (LP40) was not active in MyD88‐deficient mice and stimulated Toll‐like receptor (TLR)‐2, but not TLR‐4. LP40 potentiated the production of IFN‐γ and IL‐10, but not IL‐4 and IL‐5 by human T cells. In addition, triggering of TLR‐2 by lipopeptides promoted the in vitro differentiation of naive T cells towards IL‐10‐ and IFN‐γ‐producing T cells and suppressed IL‐4 production by Th2 cells. Accordingly, LP40 inhibited IgE production induced by allergen, anti‐IgD antibody, Nippostrongylus brasiliensis or murine acquired immunodeficiency virus. Furthermore, ovalbumin‐induced lung eosinophilic inflammation was abolished and Schistosoma mansoni egg‐induced granuloma size and eosinophil counts were suppressed in mice by LP40. These results demonstrate that stimulation of TLR‐2 by lipopeptides represents a novel way for possible treatment of allergy and asthma by regulating the disrupted cytokine balance.

High frequency of non-B subtypes in newly diagnosed HIV-1 infections in Switzerland.

HIV-1 subtypes were determined in newly diagnosed residents of Switzerland. Blood was anonymously collected from patients with a first confirmed positive HIV-1 test result. Viral DNA from the env V3-V5 region was amplified by nested polymerase chain reaction (PCR) and screened for subtype B by heteroduplex mobility assay. All amplicons not identified as B were sequenced. From November 1996 to February 1998, 206 samples were analyzed. Main transmission risks were unprotected heterosexual (55.7%) or homosexual (27.1%) sexual contact or intravenous drug use (12.9%). Subtype B dominated in patients of Swiss, other European, American, or Asian citizenship; particularly high frequencies were found in homosexuals (97%) and drug users (94%). Non-B subtypes including A, C, D, E, F, G, H, a possible B/F recombinant, and a sequence related to J were present in 28.2% (95% confidence interval [CI], 22.9%-35.0%). Non-B were frequent in African citizens (95%), heterosexually infected individuals (44%), and women (43%). Heterosexually infected Swiss males harbored non-B strains in 18% and females in 33%. The results document a change in the epidemiology of newly diagnosed HIV-1 infections in Switzerland: predominance of heterosexual transmission and a high frequency of non-B subtypes.

Enhanced gene silencing by the application of multiple specific small interfering RNAs

Small interfering RNA duplexes (siRNA) induce gene silencing in various eukaryotic cells, although usually in an incomplete manner. Using chemically synthesized siRNAs targeting the HIV‐1 co‐receptor CXCR4 or the apoptosis‐inducing Fas‐ligand (FasL), co‐transfection of cells with two or more siRNA duplexes targeting different sites on the same mRNA resulted in an enhanced gene silencing compared with each single siRNA. This was shown in the down‐regulation of protein and mRNA expression, and functionally in the inhibition of CXCR4‐mediated HIV infection and of FasL‐mediated cell apoptosis. Transfection efficiency determined for the FasL‐specific siRNAs was dose‐dependent and varied among the siRNAs tested, but was not the main reason for the enhanced gene silencing.

High prevalence and coinfection rate of hepatitis G and C infections in intravenous drug addicts

BACKGROUND/AIMS The hepatitis G virus is a newly discovered RNA virus which is possibly transmitted parenterally. Hepatitis G virus is associated with acute or chronic hepatitis and may lead to cirrhosis and liver cancer, characteristics shared by the hepatitis C virus. Hepatitis C virus is prevalent in drug users, but the frequency and role of hepatitis G virus is not yet well established. METHODS One hundred and seventeen heavy i.v. drug users were enrolled in a prospective, controlled, randomized study for i.v. administration of heroin and/or methadone. Hepatitis G virus was detected using a hot start polymerase chain reaction followed by an ELISA polymerase chain reaction assay. Hepatitis C virus genotyping was done using the Inno-Lipa strip assay. RESULTS Hepatitis G virus infection was detected in 35% (41/117) of the study population and hepatitis C virus infection in 95.7% (112/117). Ninety-seven percent of hepatitis G virus positive patients were coinfected with hepatitis C virus, of whom 75% were infected with hepatitis C virus genotype 3a. This genotype was prevalent in 48.3% of patients infected with hepatitis C virus alone. The presence or absence of hepatitis G virus infection had no influence on chronic hepatitis. Twenty-two percent of patients who started injecting heroin before 1980 and 40% of those who started after 1980 were hepatitis G virus positive. Overall, 16 patients were infected with human immunodeficiency virus, six were coinfected with hepatitis G virus and hepatitis C virus, and 10 only with hepatitis C virus. CONCLUSIONS Hepatitis G virus infection is highly prevalent in i.v. drug users, but less frequent than hepatitis C virus infection. The fact that all but two patients were coinfected with hepatitis C virus, 75% with one genotype, supports a common route of transmission for both viruses. The course of hepatitis C virus infection is not altered by hepatitis G virus infection.