The brain is a target organ for recreational drugs and HIV-1. Epidemiological data demonstrate that opioid abuse is a risk factor for HIV-1 infection and progression to AIDS. Chemokines and their receptors have been implicated in the neuropathogenesis of HIV-1 infections. However, little is known about the effects of opioids on the expression of chemokines and their receptors (the latter also are HIV-1 coreceptors) by cells of the CNS. Herein we describe the effects of morphine on gene expression of the α- and β-chemokines and their receptors by the astrocytoma cell line U87 and by primary normal human astrocyte (NHA) cultures. U87 cells treated with morphine showed significant down-regulation of IL-8 gene expression, whereas expression of the IL-8 receptor CXCR2 was reciprocally up-regulated as detected by RT-PCR. Treatment of NHAs with morphine suppressed IL-8 and macrophage-inflammatory protein-1β gene expression, whereas expression of their receptor genes, CCR3 and CCR5, was simultaneously enhanced. These morphine-induced effects on U87 and NHA cells were reversed by the opioid μ receptor antagonist β-funaltrexamine. Morphine also enhanced the constitutive expression of the opioid μ receptor on astroglial cells. Our results support the hypothesis that opioids play a significant role in the susceptibility of the CNS to HIV-1 infection and subsequent encephalopathy by inhibiting local production of HIV-1-protective chemokines (IL-8 and macrophage-inflammatory protein-1β) and enhancing expression of HIV-1 entry coreceptor genes (CCR3, CCR5, and CXCR2) within the CNS. These effects of opioids appear to be mediated through the opioid μ receptor that we demonstrated on astroglial cells.

Human immunodeficiency virus (HIV)-1 patients who abuse opiates are at a greater risk of developing neurological complications of AIDS. Alterations in blood-brain barrier (BBB) integrity are associated with cytoskeletal disorganization and disruption of tight junction (TJ) integrity. We hypothesize that opiates in combination with HIV-1 viral proteins can modulate TJ expression in primary brain microvascular endothelial cells (BMVEC), thereby compromising BBB integrity and exacerbating HIV-1 neuropathogenesis. We investigated the effect of morphine and/or tat on the expression of TJ proteins ZO-1, JAM-2, Occludin and P-glycoprotein and the functional effects of TJ modulation in BMVEC. Morphine and/or tat, via the activation of pro-inflammatory cytokines, intracellular Ca(2+) release, and activation of myosin light chain kinase, modulated TJ expression resulting in decreased transendothelial electric resistance and enhanced transendothelial migration across the BBB. These studies may lead to the development of novel anti-HIV-1 therapeutics that target specific TJ proteins, thus preventing TJ disruption in opiate using HIV-1 patients.

No abstract

In the field of transplantation, flow cytometry serves a well-established role in pre-transplant crossmatching and monitoring immune reconstitution following hematopoietic stem cell transplantation. The capabilities of flow cytometers have continuously expanded and this combined with more detailed knowledge of the constituents of the immune system, their function and interaction and newly developed reagents to study these parameters have led to additional utility of flow cytometry-based analyses, particularly in the post-transplant setting. This review discusses the impact of flow cytometry on managing alloantigen reactions, monitoring opportunistic infections and graft rejection and gauging immunosuppression in the context of solid organ transplantation.