Transforming growth factor-beta1 increases CXCR4 expression, stromal-derived factor-1alpha-stimulated signalling and human immunodeficiency virus-1 entry in human monocyte-derived macrophages.

Stromal-derived factor-1 (SDF-1/CXCL12) and its receptor CXCR4 play crucial roles in leukocyte migration and activation, as well as embryogenesis, angiogenesis, cancer and viral pathogenesis. CXCR4 is one of the major human immunodeficiency virus-1 (HIV-1) coreceptors on macrophages. In many tissues macrophages are one of the predominant cell types infected by HIV-1 and act as a reservoir for persistent infection and viral dissemination. In patients infected by HIV-1, blood and tissue levels of transforming growth factor-beta1 (TGF-beta1) are increased. The purpose of this study was to evaluate the effects of TGF-beta1 on CXCR4 expression and function in primary human monocyte-derived macrophages (MDMs) and rat microglia. TGF-beta1 up-regulated CXCR4 and enhanced SDF-1alpha-stimulated ERK1,2 phosphorylation in these cells. The increased CXCR4 expression in human MDMs resulted in increased susceptibility of the cells to entry by dual-tropic CXCR4-using HIV-1 (D-X4). In contrast, TGF-beta1 failed to increase CCR5 expression or infection by a CCR5-using virus in MDMs. Our data demonstrate that TGF-beta1 enhances macrophage responsiveness to SDF-1alpha stimulation and susceptibility to HIV-1 by selectively increasing expression of CXCR4. The results suggest that increased expression of CXCR4 on macrophages may contribute to the emergence of dual-tropic X4 viral variants at later stages of HIV-1 infection.

Impact on genetic networks in human macrophages by a CCR5 strain of human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) impacts multiple lineages of hematopoietic cells, including lymphocytes and macrophages, either by direct infection or indirectly by perturbations of cell networks, leading to generalized immune deficiency. We designed a study to discover, in primary human macrophages, sentinel genetic targets that are impacted during replication over the course of 7 days by a CCR5-using virus. Expression of mRNA and proteins in virus- or mock-treated macrophages from multiple donors was evaluated. Hierarchical agglomerative cluster analysis grouped into distinct temporal expression patterns >900 known human genes that were induced or repressed at least fourfold by virus. Expression of more than one-third of the genes was induced rapidly by day 2 of infection, while other genes were induced at intermediate (day 4) or late (day 7) time points. More than 200 genes were expressed exclusively in either virus- or mock-treated macrophage cultures, independent of the donor, providing an unequivocal basis to distinguish an effect by virus. HIV-1 altered levels of mRNA and/or protein for diverse cellular programs in macrophages, including multiple genes that can contribute to a transition in the cell cycle from G(1) to G(2)/M, in contrast to expression in mock-treated macrophages of genes that maintain G(0)/G(1). Virus treatment activated mediators of cell cycling, including PP2A, which is impacted by Vpr, as well as GADD45 and BRCA1, potentially novel targets for HIV-1. The results identify interrelated programs conducive to optimal HIV-1 replication and expression of genes that can contribute to macrophage dysfunction.

Methylphenidate does not improve cognitive function in healthy sleep-deprived young adults.

BACKGROUND: Abuse of methylphenidate, a treatment of attention-deficit/hyperactivity disorder, is reported to be increasing among students for the purpose of improving cognition. METHODS: A single capsule, containing methylphenidate (20 mg) or placebo, was administered to healthy young adults orally following 24 hours of sleep deprivation. Measurements included percent change in score from sleep-deprived baseline on four standardized tests of cognitive function: Hopkins Verbal Learning, Digit Span, Modified Stroop, and Trail Making tests. Measurements also included percent changes in blood pressure and heart rate from sleep-deprived baseline and plasma methylphenidate concentration. RESULTS: Differences in cognitive test performance were not observed between intervention groups. In subjects receiving methylphenidate, mean percent changes from baseline for systolic blood pressure and heart rate were increased relative to placebo between 90 and 210 minutes following capsule administration (maximum increases of 9.45% and 11.03%, respectively). The timing of peak differences in physiologic measures did not correlate with peak serum methylphenidate concentrations. Exit questionnaire ratings of "capsule effect" and perceived performance on the postcapsule administration of the most challenging cognitive test were both higher (p = .044 and p = .009, respectively) for the methylphenidate group than for the placebo group. CONCLUSIONS: Cognitive improvement among sleep-deprived young adults was not observed following methylphenidate administration. Benefits perceived by abusers may relate to increased confidence and sense of well-being, as well as to sympathetic nervous system stimulation. Moreover, methylphenidate administration results in physiologic effects that could be harmful to certain individuals.