Macrophage HIV-1 infection in duodenal tissue of patients on long term HAART.

Mucosal surfaces play a major role in human immunodeficiency virus type 1 (HIV-1) transmission and pathogenesis. Since the role of intestinal macrophages as viral reservoirs during chronic HIV-1 infection has not been elucidated, we investigated the effects of successful therapy on intestinal HIV-1 persistence. Intestinal macrophage infection was demonstrated by the expression of p24 antigen by flow cytometry and by the presence of proviral DNA, assessed by PCR. Proviral DNA was detected in duodenal mucosa of HIV-infected patients under treatment with undetectable plasma viral load. These findings confirm that intestinal macrophages can act as viral reservoirs and permit HIV-1 production even after viral suppression following antiretroviral therapy.

Increased lymphocyte viability after non-stimulated peripheral blood mononuclear cell (PBMC) culture in patients with X-linked lymphoproliferative disease (XLP).

Survival of lymphocytes after prolonged culture was studied in two asymptomatic XLP patients. Viability of XLP PBMC after 30 days of non-stimulated culture was higher than that of normal controls (N), mainly due to the persistence of CD8 memory lymphocytes. IFNgamma high CD8 T lymphocytes remained higher in XLP than in N after 30 days. The number of perforin+ CD8 lymphocytes was markedly reduced after 30 days in XLP and in N. Increased viability was not related to CD127, PD-1, CD27, or CD62L expression. Concerning B lymphocytes, memory CD27+ CD19+ cells prevailed over CD27- cells after 30 days in both XLP and N, with far more surviving cells in XLP. In N, few CD19+ B lymphocytes were viable after prolonged culture. In XLP, these cells were also IgD+, IgM+ and EBNA2+. These results demonstrate that IFNgamma-positive memory CD8 T cells persist in XLP after prolonged culture in association with a subset of viable memory CD27+ B cells expressing latent EBV antigens. The survival advantage of XLP cells might be related to increased frequency of extranodal lymphoma in XLP patients.

[The role of dendritic cells in the infection by HIV and HCV]. / Papel de las celulas dendriticas en la infeccion por HIV y HCV.

Dendritic cells are most important as antigen presenting cells during the induction of an effective immune response. Therefore, it is important to study their role during the generation of persistent or chronic viral infections, such as HIV or HCV infection. In this review we shall describe the phenotypic and functional characteristics of the different classes of dendritic cells and of their membrane receptors. Their participation in defence or facilitation mechanisms involved in the immune response against these viruses will be discussed. It is important to take this knowledge into account when trying to design therapeutic strategies for protection or reconstruction of the immune system that may be altered as a consequence of infection with HIV or HCV.

Impact of human immune deficiency virus infection on hepatitis C virus infection and replication.

Human immune deficiency virus (HIV) and human hepatitis C virus (HCV) infection are frequent in patients who have been exposed to blood or blood-derived products. It has been suggested that HIV infection increases HCV replication altering the course of HCV-related disease. However, it is not known if HIV directly enhances HCV replication or if its effect is the consequence of HIV infection of other cell types that control HCV replication (lymphocytes, macrophages). While the main cell targets for HIV infection are mononuclear leukocytes bearing CD4 and the chemokine receptors CCR5 and CXCR4, HCV was originally thought to be strictly hepatotropic, but it is now known that HCV can also replicate in peripheral blood mononuclear cells (PBMC). Therefore, in co-infected individuals, these two different viruses could share cell targets and interact either directly or indirectly. Some membrane receptors can be used by both HCV and HIV for entry into target cells, but the intracellular mechanisms shared by these viruses are not known. Lack of experimental systems providing suitable methods for the study of HCV replication in the presence or absence of HIV co-infection has hampered advances in this research area, but recent investigations are currently going on in order to answer these questions. This is an important issue, as knowledge of HIV/HCV interactions is required for the design of effective antiviral therapies.

Papel de las células dendríticas en la infección por HIV y HCV / The role of dendritic cells in the infection by HIV and HCV

Las células dendríticas son las principales células presentadoras de antígenos para el montaje de la respuesta inmune. Por lo tanto es importante estudiar de qué manera intervienen en el equilibrio que el sistema inmune desarrolla frente a infecciones virales persistentes como la infección por el HIV o el HCV. En esta revisión se presentan en primer término generalidades sobre las diferentes clases de células dendríticas, las características fenotípicas y funcionales que las definen y los receptores que pueden estar involucrados en la infección viral. Luego se analiza su participación en los mecanismos de defensa o facilitadores de la infección por estos virus. Es importante tener en cuenta estos conocimientos para poder diseñar adecuadas estrategias de vacunación o protección y para intentar la reconstrucción funcional del sistema inmune impidiendo la subversión de los mecanismos inmunes de defensa causada por la infección con el HIV y el HCV.

Dendritic cells are most important as antigen presenting cells during the induction of an effective immune response. Therefore, it is important to study their role during the generation of persistent or chronic viral infections, such as HIV or HCV infection. In this review we shall describe the phenotypic and functional characteristics of the different classes of dendritic cells and of their membrane receptors. Their participation in defence or facilitation mechanisms involved in the immune response against these viruses will be discussed. It is important to take this knowledge into account when trying to design therapeutic strategies for protection or reconstruction of the immune system that may be altered as a consequence of infection with HIV or HCV.

Papel de las células dendríticas en la infección por HIV y HCV / The role of dendritic cells in the infection by HIV and HCV

Las células dendríticas son las principales células presentadoras de antígenos para el montaje de la respuesta inmune. Por lo tanto es importante estudiar de qué manera intervienen en el equilibrio que el sistema inmune desarrolla frente a infecciones virales persistentes como la infección por el HIV o el HCV. En esta revisión se presentan en primer término generalidades sobre las diferentes clases de células dendríticas, las características fenotípicas y funcionales que las definen y los receptores que pueden estar involucrados en la infección viral. Luego se analiza su participación en los mecanismos de defensa o facilitadores de la infección por estos virus. Es importante tener en cuenta estos conocimientos para poder diseñar adecuadas estrategias de vacunación o protección y para intentar la reconstrucción funcional del sistema inmune impidiendo la subversión de los mecanismos inmunes de defensa causada por la infección con el HIV y el HCV.(AU)

Dendritic cells are most important as antigen presenting cells during the induction of an effective immune response. Therefore, it is important to study their role during the generation of persistent or chronic viral infections, such as HIV or HCV infection. In this review we shall describe the phenotypic and functional characteristics of the different classes of dendritic cells and of their membrane receptors. Their participation in defence or facilitation mechanisms involved in the immune response against these viruses will be discussed. It is important to take this knowledge into account when trying to design therapeutic strategies for protection or reconstruction of the immune system that may be altered as a consequence of infection with HIV or HCV. (AU)

HIV-1 infection and chemokine receptor modulation.

In addition to the CD4 molecule that binds to the human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein gp120, productive HIV-1 infection requires interaction with cellular receptors for alpha- or beta- chemokines (CXCR4 and CCR5 respectively). Isolates of HIV-1 exhibit different tropism depending on the chemokine receptor type that they use to infect their cellular targets. HIV-1 strains that use preferentially CCR5 are known as R5 strains. They are more frequently found in asymptomatic individuals during the initial stages of the disease and are involved in the transmision of infection from mother to child. HIV-1 species using CXCR4 (X4 strains) are observed mainly in patients with advanced disease. While X4 isolates are associated with syncitium formation, in general R5 strains are not. Interaction of X4 and R5 with their specific receptors is necessary to establish productive HIV-1 infection and trigger a series of intracellular signals. Modulation of CXCR4 and CCR5 expression after HIV-1 infection is one of the results of such interaction and may have important consequences on the course of the infection. Down regulation of CCR5 and CXCR4 after HIV-1 infection could be the result of indirect events linked to HIV-1 infection, such as the induction of alpha- or beta-chemokines competing with the virions for receptor binding. They could also reflect direct effects of HIV-1 on chemokine-receptor turnover. In this review, the mechanisms of modulation of CXCR4 and CCR5 expression after HIV-1 infection will be discussed.

Loss of circulating CD27+ memory B cells and CCR4+ T cells occurring in association with elevated EBV loads in XLP patients surviving primary EBV infection.

Detailed longitudinal studies of patients with X-linked lymphoproliferative disease (XLP) may increase our understanding of the immunologic defects that contribute to the development of lymphoma and hypogammaglobulinemia in XLP. We describe progressive changes observed in immunoglobulin concentrations, lymphocyte subsets, and Epstein-Barr virus (EBV) loads occurring in a 2-year period in a newly infected, but otherwise healthy, carrier (patient 9). We compare these findings with those observed in the patient's brother, who had hypogammaglobulinemia and XLP (patient 4). Immunoglobulin G (IgG), IgM, and IgA concentrations increased in patient 9 during acute EBV infection, but thereafter they decreased steadily to concentrations consistent with hypogammaglobulinemia, reaching a plateau 5 months after infection. In both patients, CD19+ B-lymphocyte rates remained lower than 3%, with a contraction of the B-cell memory compartment (CD27+ CD19+/CD19+) to 20% (normal range, 32%-56%). T-lymphocyte subpopulations showed a reduction in CD4+ T-cell counts and a permanent CD8+ T-cell expansion. Interestingly, CXCR3 memory TH1 cells were expanded and CCR4+ TH2 lymphocytes were reduced, suggesting that abnormal skewing of memory T-cell subsets might contribute to reduced antibody synthesis. Despite an expanded number of CD3+CD8+ lymphocytes, increased EBV loads occurred in both patients without overt clinical symptoms of mononucleosis, lymphoproliferative disease, or lymphoma.

[X-linked lymphoproliferative syndrome, EBV virus infection and defects in cytotoxicity lymphocyte regulation]. / Sindrome linfoproliferativo ligado al cromosoma X, infección por el virus EBV y defectos en la regulación de la citotoxicidad linfocitaria.

Mutations in SH2D1A, a gene that codifies for the regulatory protein SAP, result in uncontrolled activation of the SLAM (signaling lymphocyte-activation molecule) pathway. This X-linked immunodeficiency becomes evident when the patients are infected with Epstein Barr virus (EBV) and develop a fulminant form of infectious mononucleosis leading to a lymphoproliferative syndrome that is often fatal (X-linked lymphoproliferative syndrome, XLP). In those who survive, hypogammaglobulinemia and oncohematologic diseases are frequently observed. In this revision, the immuno-regulatory mechanisms involved in XLP immunopathology and the role of different effector cells (CD8 T lymphocytes, NK cells) are discussed.

Sindrome linfoproliferativo ligado al cromosoma X, infeccion por el virus EBV y defectos en la regulacion de la citotoxicidad linfocitaria / X-linked lymphoproliferative syndrome, EBV virus infection and defects in cytotoxicity lymphocyte regulation

Mutations in SH2D1A, a gene that codifies for the regulatory protein SAP, result in uncontrolled activation of the SLAM (signaling lymphocyte-activation molecule) pathway. This X-linked immunodeficiency becomes evident when the patients are infected with Epstein Barr virus (EBV) and develop a fulminant form of infectious mononucleosis leading to a lymphoproliferative syndrome that is often fatal (X-linked lymphoproliferative syndrome, XLP). In those who survive, hypogammaglobulinemia and oncohematologic diseases are frequently observed. In this revision, the immuno-regulatory mechanisms involved in XLP immunopathology and the role of different effector cells (CD8 T lymphocytes, NK cells) are discussed

Sindrome linfoproliferativo ligado al cromosoma X, infección por el virus EBV y defectos en la regulación de la citotoxicidad linfocitaria. / [X-linked lymphoproliferative syndrome, EBV virus infection and defects in cytotoxicity lymphocyte regulation]

Mutations in SH2D1A, a gene that codifies for the regulatory protein SAP, result in uncontrolled activation of the SLAM (signaling lymphocyte-activation molecule) pathway. This X-linked immunodeficiency becomes evident when the patients are infected with Epstein Barr virus (EBV) and develop a fulminant form of infectious mononucleosis leading to a lymphoproliferative syndrome that is often fatal (X-linked lymphoproliferative syndrome, XLP). In those who survive, hypogammaglobulinemia and oncohematologic diseases are frequently observed. In this revision, the immuno-regulatory mechanisms involved in XLP immunopathology and the role of different effector cells (CD8 T lymphocytes, NK cells) are discussed.

Sindrome linfoproliferativo ligado al cromosoma X, infeccion por el virus EBV y defectos en la regulacion de la citotoxicidad linfocitaria / X-linked lymphoproliferative syndrome, EBV virus infection and defects in cytotoxicity lymphocyte regulation

Mutations in SH2D1A, a gene that codifies for the regulatory protein SAP, result in uncontrolled activation of the SLAM (signaling lymphocyte-activation molecule) pathway. This X-linked immunodeficiency becomes evident when the patients are infected with Epstein Barr virus (EBV) and develop a fulminant form of infectious mononucleosis leading to a lymphoproliferative syndrome that is often fatal (X-linked lymphoproliferative syndrome, XLP). In those who survive, hypogammaglobulinemia and oncohematologic diseases are frequently observed. In this revision, the immuno-regulatory mechanisms involved in XLP immunopathology and the role of different effector cells (CD8 T lymphocytes, NK cells) are discussed (AU)

Decreased recovery of replication-competent HIV-1 from peripheral blood mononuclear cell-derived monocyte/macrophages of HIV-positive patients after 3 years on highly active antiretroviral therapy.

We studied the release of p24 antigen from peripheral blood mononuclear cell-derived monocyte/macrophages obtained from 13 HIV-positive patients receiving highly active antiretroviral therapy (HAART). Although HIV-infected monocyte/macrophages were detected in 80% of patients after 36 months of continuous treatment, additional exposure to HAART reduced the chance of detecting HIV-releasing monocyte/macrophages. Therefore, after more than 3 years of HAART, recently infected monocytes may play a less important role as a source of emerging HIV-1 upon HAART interruption.

Expresión de co-receptores para el virus de la inmunodeficiencia humana (VIH) luego del cultivo de leucócitos mononucleares (LM) de pacientes VIH+ / Human immunodeficiency virus (HIV) co-receptors expression in mononuclear leucocytes (ML) of HIV+ patients

Se estudiaron variaciones en la expresión de los co-receptores CXCR4 y CCR5 luego del cultivo no estimulado de LM de pacientes VIH+ por periodos de 3 a 20 días. El porcentaje de células CCR5+ descendió tanto en linfocitos T CD4+ como en T CD8+ luego de 7 días, manteniéndose disminuido hasta los 20 días. En cambio los niveles de CXCR4 se mantuvieron estables durante el cultivo en ambas subpoblaciones. En los cultivos de LM de donantes VIH- no hubo cambios significativos en la expresión de CCR5 ni en la de CXCR4. Para comprobar si la disminución de CCR5 estaba asociada a la replicación viral, se infectaron LM VIH- (pre-cultivados por 6 días) con sobrenadantes de cultivos de LM VIH+. Luego de 3 días de infección, la expresión de CCR5 se redujo tanto en linfocitos T CD4+ como en linfocitos T CD8+ , coincidiendo con la replicación viral durante el cultivo.

Macrófagos infectados por HIV aislados de pacientes HIV+ con carga viral indetectable luego del tratamiento antirretroviral combinado / HIV infected macrophages isolated from HIV+ patients with undetectable viral load undergoing combined antiretroviral treatment

Se desarrolló un método de cultivo prolongado de células mononucleares periféricas, sin estímulo (CMP s/e) que permite la proliferación y diferenciación completa de los macrófagos (M). Con el mismo se demostró la replicación in vitro del HIV en pacientes HIV+ con carga viral negativa luego de más de un año de tratamiento HAART. Las células infectadas siempre fueron M. Utilizando el sistema estándar de co-cultivo con CPM activadas con PHA e IL-2 (CM-PHA) no se habían logrado aislamientos de estos pacientes. Los sobrenadantes (SN) con p24> 65 pg/ml fueron infectivos para target CMP s/e normales, pre-cultivados 6-7 días. Em comparación se utilizaron CMP-PHA. Em CMP predominan los M proliferantes (CD64+, Ki67+) y en CMP-PHA los blastos T (CD3+, Ki67). La expresión de CCR5 fue mayor en CMP s/e que en CMP-PHA. Estas diferencias pueden explicar por qué el sistema CMP s/e es má sensible que CMP-PHA para detectar la infección por HIV en pacientes asintomáticos con carga viral indetectable, con cepas de HIV macrófago trópicas (R5).

Expresión de co-receptores para el virus de la inmunodeficiencia humana (VIH) luego del cultivo de leucócitos mononucleares (LM) de pacientes VIH+ / Human immunodeficiency virus (HIV) co-receptors expression in mononuclear leucocytes (ML) of HIV+ patients

Se estudiaron variaciones en la expresión de los co-receptores CXCR4 y CCR5 luego del cultivo no estimulado de LM de pacientes VIH+ por periodos de 3 a 20 días. El porcentaje de células CCR5+ descendió tanto en linfocitos T CD4+ como en T CD8+ luego de 7 días, manteniéndose disminuido hasta los 20 días. En cambio los niveles de CXCR4 se mantuvieron estables durante el cultivo en ambas subpoblaciones. En los cultivos de LM de donantes VIH- no hubo cambios significativos en la expresión de CCR5 ni en la de CXCR4. Para comprobar si la disminución de CCR5 estaba asociada a la replicación viral, se infectaron LM VIH- (pre-cultivados por 6 días) con sobrenadantes de cultivos de LM VIH+. Luego de 3 días de infección, la expresión de CCR5 se redujo tanto en linfocitos T CD4+ como en linfocitos T CD8+ , coincidiendo con la replicación viral durante el cultivo. (AU)

Macrófagos infectados por HIV aislados de pacientes HIV+ con carga viral indetectable luego del tratamiento antirretroviral combinado / HIV infected macrophages isolated from HIV+ patients with undetectable viral load undergoing combined antiretroviral treatment

Se desarrolló un método de cultivo prolongado de células mononucleares periféricas, sin estímulo (CMP s/e) que permite la proliferación y diferenciación completa de los macrófagos (M). Con el mismo se demostró la replicación in vitro del HIV en pacientes HIV+ con carga viral negativa luego de más de un año de tratamiento HAART. Las células infectadas siempre fueron M. Utilizando el sistema estándar de co-cultivo con CPM activadas con PHA e IL-2 (CM-PHA) no se habían logrado aislamientos de estos pacientes. Los sobrenadantes (SN) con p24> 65 pg/ml fueron infectivos para target CMP s/e normales, pre-cultivados 6-7 días. Em comparación se utilizaron CMP-PHA. Em CMP predominan los M proliferantes (CD64+, Ki67+) y en CMP-PHA los blastos T (CD3+, Ki67). La expresión de CCR5 fue mayor en CMP s/e que en CMP-PHA. Estas diferencias pueden explicar por qué el sistema CMP s/e es má sensible que CMP-PHA para detectar la infección por HIV en pacientes asintomáticos con carga viral indetectable, con cepas de HIV macrófago trópicas (R5). (AU)