Sustained elevation of kynurenic Acid in the cerebrospinal fluid of patients with herpes simplex virus type 1 encephalitis.

Herpes simplex virus (HSV) type 1 encephalitis (HSE) is a viral infectious disease with commonly occurring neurodegeneration and neurological/cognitive long-term sequelae. Kynurenic acid (KYNA) is a neuroactive tryptophan metabolite, which is elevated in the cerebrospinal fluid (CSF) during viral infection as a result of immune activation. The aim of the study was to investigate the role of endogenous brain KYNA for the long-term outcome of the disease.

CD27(-) B-cells produce class switched and somatically hyper-mutated antibodies during chronic HIV-1 infection.

Class switch recombination and somatic hypermutation occur in mature B-cells in response to antigen stimulation. These processes are crucial for the generation of functional antibodies. During HIV-1 infection, loss of memory B-cells, together with an altered differentiation of naïve B-cells result in production of low quality antibodies, which may be due to impaired immunoglobulin affinity maturation.

Altered expression of the receptor-ligand pair CXCR5/CXCL13 in B cells during chronic HIV-1 infection.

HIV-1 infection is associated with B-cell abnormalities, such as hypergammaglobulinemia, poor immunization responses, and loss of serologic memory. To determine whether altered expression of chemokine receptors and their ligands may play a role in B-cell dysfunctions during HIV-1 infection, the expression of CXC chemokine receptor 4 (CXCR4), CXCR5, and CC chemokine receptor 7 (CCR7) and their respective ligands on CD19(+) B cells were examined in HIV-1-infected patients and controls. We report a decreased CXCR5 expression on B cells from patients (P < .

Potential role of CD8+CD28- T lymphocytes in immune activation during HIV-1 infection.

As CD8+CD28- T cells have been associated with dendritic and T cell suppression, we analyzed whether an increase in CD8+CD28- T cell numbers during HIV-1 infection could lead to impaired T cell responses. In contrast to the in-vitro generated CD8+CD28- suppressors, peripheral blood CD8+CD28- T cells of both HIV-infected and noninfected individuals promoted dendritic cell activation. The CD8+CD28- T cell accumulation during HIV-1 infection may thus contribute to accelerated inflammatory reactions and immune activation.

Priming of T cells to Fas-mediated proliferative signals by interleukin-7.

T-cell depletion associated with HIV infection or cytoreductive therapies triggers potential T-cell regenerative mechanisms such as peripheral T-lymphocyte expansion to weak antigenic stimuli and the increased availability of interleukin-7 (IL-7), a cytokine with potent antiapoptotic and proliferative activities. Deleterious mechanisms also associated with lymphopenia, such as increased Fas expression and apoptosis of T cell, however, may result in opposing effects. In this study, we show that Fas molecules, primarily associated with T-cell depletion in lymphopenic settings, may also contribute to compensatory T-cell expansion through transmitting costimulatory signals to suboptimally activated T cells.

Broadly immunogenic HLA class I supertype-restricted elite CTL epitopes recognized in a diverse population infected with different HIV-1 subtypes.

The genetic variations of the HIV-1 virus and its human host constitute major obstacles for obtaining potent HIV-1-specific CTL responses in individuals of diverse ethnic backgrounds infected with different HIV-1 variants. In this study, we developed and used a novel algorithm to select 184 predicted epitopes representing seven different HLA class I supertypes that together constitute a broad coverage of the different HIV-1 strains as well as the human HLA alleles. Of the tested 184 HLA class I-restricted epitopes, 114 were recognized by at least one study subject, and 45 were novel epitopes, not previously described in the HIV-1 immunology database.

Potential role for IL-7 in Fas-mediated T cell apoptosis during HIV infection.

IL-7 promotes survival of resting T lymphocytes and induces T cell proliferation in lymphopenic conditions. As elevated IL-7 levels occur in HIV-infected individuals in addition to high Fas expression on T cells and increased sensitivity to Fas-induced apoptosis, we analyzed whether IL-7 has a regulatory role in Fas-mediated T cell apoptosis. We show that IL-7 up-regulates Fas expression on naive and memory T cells through a mechanism that involves translocation of Fas molecules from intracellular compartments to the cell membrane.

Loss of memory B cells impairs maintenance of long-term serologic memory during HIV-1 infection.

Circulating memory B cells are severely reduced in the peripheral blood of HIV-1-infected patients. We investigated whether dysfunctional serologic memory to non-HIV antigens is related to disease progression by evaluating the frequency of memory B cells, plasma IgG, plasma levels of antibodies to measles, and Streptococcus pneumoniae, and enumerating measles-specific antibody-secreting cells in patients with primary, chronic, and long-term nonprogressive HIV-1 infection. We also evaluated the in vitro production of IgM and IgG antibodies against measles and S pneumoniae antigens following polyclonal activation of peripheral blood mononuclear cells (PBMCs) from patients.

Acute psychotic symptoms in HIV-1 infected patients are associated with increased levels of kynurenic acid in cerebrospinal fluid.

Human immunodeficiency virus type 1 (HIV-1) infection is associated with psychiatric complications including cognitive impairment, affective disorders, and psychosis. Previous studies have revealed a disturbed kynurenine metabolism in these patients leading to increased levels of neuroactive compounds acting at glutamatergic neurotransmission. Kynurenic acid (KYNA), one of these metabolites is a glutamate-receptor antagonist, preferentially blocking the glycine site of the N-methyl-d-aspartate (NMDA) receptor.

Loss of IL-7Ralpha is associated with CD4 T-cell depletion, high interleukin-7 levels and CD28 down-regulation in HIV infected patients.

Objective: Elevated levels of interleukin (IL)-7 are present in the blood of HIV-positive patients and it is known that IL-7 receptor (IL-7R)alpha expression decreases on T cells during HIV infection. The subset(s) of T cells with low IL-7Ralpha and the consequence of low IL-7Ralpha expression for T-cell survival are poorly characterized.

Design: The frequency of IL-7Ralpha-negative T cells in HIV-positive patients was studied in relation to CD4 T-cell counts, IL-7 concentration and survival in culture.

Impact of HIV type 1 genetic subtype on the outcome of antiretroviral therapy.

The objective of this study was to investigate the short-term virological outcome of antiretroviral combination therapy (ART) in relation to infection with different HIV-1 genetic subtypes. Antiretroviral drug-naive patients in Sweden were prospectively enrolled and followed for 6 months when starting ART in the period from January 1998 to January 2002. Plasma-HIV-1 RNA levels, CD4 counts, and type of ART regimen were recorded.

Effects of potent antiretroviral therapy on the immune activation marker soluble CD27 in patients infected with HIV-1 subtypes A-D.

HIV-1 genetic subtypes might have a different impact on disease progression and response to antiretroviral therapy (ART). Few data are available on the immune activation profile in patients with different HIV-1 subtypes. We have tested by ELISA the plasma levels of an immune activation marker, soluble CD27 (sCD27), in a cohort of 64 patients infected with HIV-1 subtypes A-D, at baseline and after 1 year of virologically successful ART.