Fat distribution in HIV-infected patients reporting truncal enlargement quantified by whole-body magnetic resonance imaging.
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BACKGROUND: Antiretroviral therapy has improved the prospects for people infected with HIV, but some develop a syndrome of profound body habitus and metabolic alterations that include truncal enlargement. OBJECTIVE: The purpose of this study was to define the body-composition changes associated with this syndrome by using techniques with the power to estimate regional body composition. DESIGN: We compared whole-body and regional skeletal muscle and adipose tissue contents measured by magnetic resonance imaging and dual-energy X-ray absorptiometry (DXA) in 26 HIV-infected patients and 26 matched control subjects. Twelve of the HIV-infected patients had evidence of truncal enlargement. RESULTS: HIV-infected men and women who noted truncal enlargement had similar amounts of skeletal muscle and subcutaneous adipose tissue but greater visceral adipose tissue than HIV-infected patients without truncal enlargement; these values were larger in men (P < 0.001) than in women (P = 0.08). The ratio of visceral to subcutaneous adipose tissue was greater in both men (P < 0.02) and women (P = 0.05) with truncal enlargement. Two subjects with MRI-confirmed visceral adiposity syndrome (VAS) were not taking protease inhibitors. CD4+ lymphocyte counts were higher (P < 0.001) and plasma viral burdens tended to be lower (P = 0.08) in HIV-infected patients with VAS. CONCLUSIONS: There was significantly more visceral adipose tissue in the subgroup of HIV-infected patients with truncal enlargement than in those without this sign. VAS occurs in both men and women, is associated with higher CD4+ lymphocyte counts and lower plasma HIV viral burdens, and is not limited to those receiving protease inhibitor therapy. (+info)
IL-13 and IFN-gamma secretion by activated T cells in HIV-1 infection associated with viral suppression and a lack of disease progression.
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The immunopathology of HIV-1 infection includes immune defects in T cell cytokine secretion, resulting in decreased Ag-specific responses. In this report, IL-13 and IFN-gamma were analyzed in progressive HIV-1 disease. Both cytokines exert positive effects on Ag presentation and inhibit HIV-1 infection of macrophages. Anti-CD3/anti-CD28-activated PBMC from HIV-1-infected individuals (n = 74) compared with uninfected subjects (n = 30) secreted significantly less IL-13 (median, 0.64 ng/ml vs 2.07 ng/ml; p < 0. 001) and IFN-gamma (median, 40.96 ng/ml vs 129.5 ng/ml; p < 0.005). Decreased IL-13 and IFN-gamma secretion in HIV infection was present in sorted CD4+ and CD8+ T cell subsets, and additional analysis determined concurrent deficiency at the protein and transcriptional level. Longitudinal analysis showed that cytokine secretion levels correlated positively with CD4 count and negatively with plasma HIV-1 viral load. Patients changing to suppressive antiretroviral therapy during the study showed increases in IL-13 and IFN-gamma secretion. Overall, results show a decline in IL-13 and IFN-gamma secretion in progressive HIV-1 infection and suggest a role for both cytokines as part of T cell adaptive responses associated with a lack of disease progression. (+info)
Histological damage in chronic hepatitis C is not related to the extent of infection in the liver.
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It has not been completely elucidated whether the liver injury induced by the hepatitis C virus (HCV) is due to direct cytopathic damage or to an immune-mediated response against HCV-infected hepatocytes. In this work, we have determined the percentage of HCV-infected hepatocytes, the histological activity index, and the viremia levels in chronically HCV-infected patients with different grades of liver injury to investigate any possible correlation between them. For that purpose, liver biopsies from 27 patients with HCV chronic hepatitis were analyzed by in situ hybridization. This technique revealed that the percentage of infected hepatocytes ranged from 0.04% to 83.6%. Regarding the viremia levels, HCV RNA concentration ranged from 1.8 x 10(3) to 1.4 x 10(6) genome copies/ml. A significant correlation (r = 0.54; P = 0.003) between the percentage of infected hepatocytes and the viremia levels was found. In contrast, no correlation was observed between the percentage of HCV-infected hepatocytes or the viremia levels and the histological activity index. In conclusion, we have shown that the HCV viremia reflects the extent of the infection in the liver and that the liver injury in chronic HCV infection is not directly related to either the number of infected hepatocytes or the serum HCV RNA concentration. (+info)
Sequence variations in human immunodeficiency virus type 1 Nef are associated with different stages of disease.
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nef alleles derived from a large number of individuals infected with human immunodeficiency virus type 1 (HIV-1) were analyzed to investigate the frequency of disrupted nef genes and to elucidate whether specific amino acid substitutions in Nef are associated with different stages of disease. We confirm that deletions or gross abnormalities in nef are rarely present. However, a comparison of Nef consensus sequences derived from 41 long-term nonprogressors and from 50 individuals with progressive HIV-1 infection revealed that specific variations are associated with different stages of infection. Five amino acid variations in Nef (T15, N51, H102, L170, and E182) were more frequently observed among nonprogressors, while nine features (an additional N-terminal PxxP motif, A15, R39, T51, T157, C163, N169, Q170, and M182) were more frequently found in progressors. Strong correlations between the frequency of these variations in Nef and both the CD4(+)-cell count and the viral load were observed. Moreover, analysis of sequential samples obtained from two progressors revealed that several variations in Nef, which were more commonly observed in patients with low CD4(+)-T-cell counts, were detected only during or after progression to immunodeficiency. Our results indicate that sequence variations in Nef are associated with different stages of HIV-1 infection and suggest a link between nef gene function and the immune status of the infected individual. (+info)
Poliovirus induces apoptosis in the mouse central nervous system.
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Poliovirus (PV) is the etiological agent of human paralytic poliomyelitis. Paralysis results from the destruction of motoneurons, a consequence of PV replication. However, the PV-induced process leading to the death of motoneurons is not well known. We investigated whether PV-induced central nervous system (CNS) injury is associated with apoptosis by using mice as animal models. Transgenic mice expressing the human PV receptor were infected intracerebrally with either the neurovirulent PV-1 Mahoney strain or a paralytogenic dose of the attenuated PV-1 Sabin strain. Nontransgenic mice were infected with a mouse-adapted PV-1 Mahoney mutant. DNA fragmentation was demonstrated in CNS tissue from paralyzed mice by visualization of DNA oligonucleosomal laddering and by enzyme-linked immunosorbent assay. Viral antigens and DNA fragmentation detected by the in situ terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling technique were colocalized in neurons of spinal cords from paralyzed mice. In addition, morphological changes characteristic of cells undergoing apoptosis were observed in motoneurons by electron microscopy. Thus, we show that PV multiplication and CNS injury during paralytic poliomyelitis are associated with apoptosis. (+info)
Genetic control and dynamics of the cellular immune response to the human T-cell leukaemia virus, HTLV-I.
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About 1% of people infected with the human T-cell leukaemia virus, type 1 (HTLV-I) develop a disabling chronic inflammatory disease of the central nervous system known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP have a vigorous immune response to HTLV-I, and it has been widely suggested that this immune response, particularly the HTLV-I-specific cytotoxic T-lymphocyte (CTL) response, causes the tissue damage that is seen in HAM/TSP. In this paper we summarize recent evidence that a strong CTL response to HTLV-I does in fact protect against HAM/TSP by reducing the proviral load of HTLV-I. We conclude that HTLV-I is persistently replicating at a high level, despite the relative constancy of its genome sequence. These results imply that antiretroviral drugs could reduce the risk of HAM/TSP by reducing the viral load, and that an effective anti-HTLV-I vaccine should elicit a strong CTL response to the virus. The dynamic nature of the infection also has implications for the epidemiology and the evolution of HTLV-I. (+info)
Synergistic effect of immunization with a peptide cocktail inducing antibody, helper and cytotoxic T-cell responses on protection against respiratory syncytial virus.
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Respiratory syncytial virus (RSV)-specific cytotoxic T lymphocytes (CTL) or neutralizing antibodies can protect against RSV infection when induced separately by immunization with synthetic peptides. In the work described here, RSV-specific neutralizing antibodies and CTLs were induced after immunization with a cocktail of peptides consisting of a B-cell mimotope (S1S-MAP), a T-helper epitope (SH:45-60) and a CTL epitope linked to a fusion (F) peptide (F/M2:81-95) that were comparable to those induced by the peptides alone. Following challenge, a 190-fold reduction in RSV titre was observed in the lungs of peptide cocktail-immunized mice. The combination of RSV-specific humoral and cellular immunity induced by the peptide cocktail was thus more effective at clearing RSV than peptide-induced humoral or cellular immunity alone. (+info)
Cytomegalovirus (CMV)-specific T cell immunity after renal transplantation mediates protection from CMV disease by limiting the systemic virus load.
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The role of cytomegalovirus (CMV)-specific cytotoxic T lymphocytes (CTLs) and T helper cells (Th) in controlling CMV infection, as detected by antigenemia assay and polymerase chain reaction (PCR) in blood leukocytes, and CMV disease was investigated in 20 renal transplant recipients. Within 3 months after transplant, CMV-specific CTL and Th responses were demonstrable in 11 (55%) and 15 (75%) patients, respectively; CMV infection was detected by antigenemia and PCR in 19 (95%) patients each. During the month of first CMV detection, there was an inverse correlation between CTL response and antigenemia at >/=20 positive cells/105 leukocytes (P=.007) but no association with lower antigenemia levels or PCR positivity. CMV disease developed in 7 (35%) patients and was associated with high-level antigenemia but was inversely correlated with detection of CTLs (P=.04). After renal transplantation, CMV-specific CTLs limit the systemic virus load as reflected by antigenemia levels and thereby mediate protection from CMV disease. (+info)