Neuronal ferritin heavy chain and drug abuse affect HIV-associated cognitive dysfunction.

Interaction of the chemokine CXCL12 with its receptor CXCR4 promotes neuronal function and survival during embryonic development and throughout adulthood. Previous studies indicated that µ-opioid agonists specifically elevate neuronal levels of the protein ferritin heavy chain (FHC), which negatively regulates CXCR4 signaling and affects the neuroprotective function of the CXCL12/CXCR4 axis. Here, we determined that CXCL12/CXCR4 activity increased dendritic spine density, and also examined FHC expression and CXCR4 status in opiate abusers and patients with HIV-associated neurocognitive disorders (HAND), which is typically exacerbated by illicit drug use. Drug abusers and HIV patients with HAND had increased levels of FHC, which correlated with reduced CXCR4 activation, within cortical neurons. We confirmed these findings in a nonhuman primate model of SIV infection with morphine administration. Transfection of a CXCR4-expressing human cell line with an iron-deficient FHC mutant confirmed that increased FHC expression deregulated CXCR4 signaling and that this function of FHC was independent of iron binding. Furthermore, examination of morphine-treated rodents and isolated neurons expressing FHC shRNA revealed that FHC contributed to morphine-induced dendritic spine loss. Together, these data implicate FHC-dependent deregulation of CXCL12/CXCR4 as a contributing factor to cognitive dysfunction in neuroAIDS.

CSF-1R up-regulation is associated with response to pharmacotherapy targeting tyrosine kinase activity in AML cell lines.

BACKGROUND: The oncogenic potential of colony stimulating factor 1 receptor (CSF-1R) has been well described, while its relevance for human acute myelogenous leukemia (AML) is still undetermined. In a recent clinical trial for AML, sunitinib was found to hold potential therapeutic benefit, however, the mechanism for this remains unknown. MATERIALS AND METHODS: In this study, we treated three myeloid cell lines, Mono-Mac 1, THP-1, and U937, with sunitinib, and a small-molecule CSF-1R inhibitor (cFMS-I) to test the anticancer effect of such treatment. RESULTS: Mono-Mac 1 cells had inhibited proliferation and extracellular-signal regulated kinase activity as a result of CSF-1R inhibition and a dose-dependent increase in CSF-1R expression with both sunitinib and cFMS-I. CONCLUSION: Our results suggest potential for CSF-1R as an important target of sunitinib or other similar drugs. Future study of CSF-1R may produce more targeted therapeutic approaches and aid in the development of personalized medicine for AML.

Macrophage colony stimulating factor regulation by nuclear factor kappa B: a relevant pathway in human immunodeficiency virus type 1 infected macrophages.

Macrophage colony stimulating factor (M-CSF) is a cytokine that promotes monocyte differentiation and survival. When overexpressed, M-CSF contributes to pathology in a wide variety of diseases, including osteoporosis, obesity, certain human cancers, and in human immunodeficiency virus type 1 (HIV-1) infection, particularly with respect to monocyte/macrophage infection and the development of HIV-1 associated central nervous system disorders. In this study, our aim was to expand the current knowledge of M-CSF regulation, focusing on nuclear factor kappa B (NF-κB), a transcription factor playing a prominent role during inflammation and HIV-1 infection. Our results suggest that tumor necrosis factor alpha (TNF-α) promotes M-CSF secretion in primary macrophages and activates the -1310/+48 bp M-CSF promoter in Mono-Mac 1 cells. Inhibitors of the NF-κB pathway diminish this response. We identified four putative NF-κB and four CCAAT-enhancer-binding protein beta binding sites within the M-CSF promoter. Our findings, using promoter constructs mutated at individual NF-κB sites within the M-CSF promoter region, suggest that these sites are redundant with respect to NF-κB regulation. TNF-α treatment promoted NF-κB p65 binding to the M-CSF promoter in phorbol 12-myristate 13-acetate (PMA) treated U937 cells chronically infected with HIV-1 (U1 cells), but not in PMA treated uninfected U937 cells, suggesting that the presence of HIV-1 increases the NF-κB response. In conclusion, our findings demonstrate that NF-κB induces M-CSF expression on a promoter level via multiple functional NF-κB binding sites and that this pathway is likely relevant in HIV-1 infection of macrophages.

Monocyte/macrophage trafficking in acquired immunodeficiency syndrome encephalitis: lessons from human and nonhuman primate studies.

Here the authors discuss evidence in human and animal models supporting two opposing views regarding the pathogenesis of human immunodeficiency virus (HIV) in the central nervous system (CNS): (1) HIV infection in the CNS is a compartmentalized infection, with the virus-infected macrophages entering the CNS early, infecting resident microglia and astrocytes, and achieving a state of latency with evolution toward a fulminant CNS infection late in the course of disease; or alternatively, (2) events in the periphery lead to altered monocyte/macrophage (MPhi) homeostasis, with increased CNS invasion of infected and/or uninfected MPhis. Here the authors have reevaluated evidence presented in the favor of the latter model, with a discussion of phenotypic characteristics distinguishing normal resident microglia with those accumulating in HIV encephalitis (HIVE). CD163 is normally expressed by perivascular MPhi s but not resident microglia in normal CNS of humans and rhesus macaques. In agreement with other studies, the authors demonstrate expression of CD163 by brain MPhi s in HIVE and simian immunodeficiency virus encephalitis (SIVE). CNS tissues from HIV-sero positive individuals with HIVE or HIV-associated progressive multifocal leukoencephalopathy (PML) were also examined. In HIVE, the authors further demonstrate colocalization of CD163 and CD16 (Fcgamma III recptor) gene expression, the latter marker associated with HIV infection of monocyte in vivo and permissivity of infection. Indeed, CD163(+) MPhis and microglia are often productively infected in HIVE CNS. In SIV infected rhesus macaques, CD163(+) cells accumulate perivascularly, within nodular lesions and the parenchyma in animals with encephalitis. Likewise, parenchymal microglia and perivascular MPhi s are CD163(+) in HIVE. In contrast to HIVE, CD163(+)perivascular and parenchymal MPhi s in HIV-associated PML were only associated with areas of demyelinating lesions. Interestingly, SIV-infected rhesus macaques whose viral burden was predominantly at 1 x 10(6) copies/ml or greater developed encephalitis. To further investigate the relationship between CD163(+)/CD16(+) MPhis/microglia in the CNS and altered homeostasis in the periphery, the authors performed flow-cytometric analyses of peripheral blood mononuclear cells (PBMCs) from SIV-infected rhesus macaques. The results demonstrate an increase in the percent frequency of CD163(+)/CD16(+) monocytes in animals with detectable virus that correlated significantly with increased viral burden and CD4(+) T-cell decline. These results suggest the importance of this monocyte subset in HIV/SIV CNS disease, and also in the immune pathogenesis of lentiviral infection. The authors further discuss the potential role of CD163(+)/CD16(+) monocyte/MPhi subset expansion, altered myeloid homeostasis, and potential consequences for immune polarization and suppression. The results and discussion here suggest new avenues for the development of acquired immunodeficiency syndrome (AIDS) therapeutics and vaccine design.

CD163/CD16 coexpression by circulating monocytes/macrophages in HIV: potential biomarkers for HIV infection and AIDS progression.

Monocytes and macrophages play a prominent role in the establishment of HIV-1 infection, virus dissemination, and development of viral reservoirs. Like T cells, macrophages display immune polarization that can promote or impair adaptive immunity. We hypothesize that dysregulation of monocyte/macrophage activation and differentiation may promote immune dysfunction and contribute to AIDS pathogenesis. Using flow cytometry, we analyzed the frequency of monocyte subsets in human immunodeficiency virus type 1 (HIV-1) infection relative to seronegative controls, focusing on the CD163(+)/CD16(+) monocyte as a likely precursor of the "alternatively activated" macrophage. Individuals with detectable HIV-1 infection showed an increase in the frequency of CD163(+)/CD16(+) monocytes (CD14(+)) when compared to seronegative or HIV-1-infected persons with undetectable viral loads. A positive correlation between increased CD163(+)/CD16(+) monocyte frequency and viral load was revealed that was not seen between viral load and the number of CD4(+) T cells or frequency of CD16(+) monocytes (without CD163 subtyping). We also found a strong inverse correlations between CD16(+) monocytes (r = -0.71, r(2) = 0.5041, p = 0.0097) or CD163(+)/CD16(+) monocytes (r = -0.86, r(2) = 0.7396, p = 0.0003) and number of CD4(+) T cells below 450 cells/microl. An inverse relationship between CD163(+)/CD16(+) and CD163(+)/CD16() monocytes suggests the expanded CD163(+)/CD16(+) population is derived exclusively from within the "alternatively activated" (MPhi-2) subset. These data suggest a potential role for CD163(+)/CD16(+) monocytes in virus production and disease progression. CD163(+)/CD16(+) monocytes may be a useful biomarker for HIV-1 infection and AIDS progression and a possible target for therapeutic intervention.

Early establishment and antigen dependence of simian immunodeficiency virus-specific CD8+ T-cell defects.

Differentiation and survival defects of human immunodeficiency virus (HIV)-specific CD8(+) T cells may contribute to the failure of HIV-specific CD8(+) T cells to control HIV replication. It is not known, however, whether simian immunodeficiency virus (SIV)-infected rhesus macaques show comparable defects in these virus-specific CD8(+) T cells or when such defects are established during infection. Peripheral blood cells from acutely and chronically infected rhesus macaques were stained ex vivo for memory subpopulations and examined by in vitro assays for apoptosis sensitivity. We show here that SIV-specific CD8(+) T cells from chronically SIV infected rhesus macaques show defects comparable to those observed in HIV infection, namely, a skewed CD45RA(-) CD62L(-) effector memory phenotype, reduced Bcl-2 levels, and increased levels of spontaneous and CD95-induced apoptosis of SIV-specific CD8(+) T cells. Longitudinal studies showed that the survival defects and phenotype are established early in the first few weeks of SIV infection. Most importantly, they appear to be antigen driven, since most probably the loss of epitope recognition due to viral escape results in the reversal of the phenotype and reduced apoptosis sensitivity, something we observed also for animals treated with antiretroviral therapy. These findings further support the use of SIV-infected rhesus macaques to investigate the phenotypic changes and apoptotic defects of HIV-specific CD8(+) T cells and indicate that such defects of HIV-specific CD8(+) T cells are the result of chronic antigen stimulation.

Macrophage colony-stimulating factor in the pathogenesis of HIV infection: potential target for therapeutic intervention.

Macrophage colony stimulating factor (M-CSF) appears to play a major role in promoting and maintaining reservoirs of human immunodeficiency virus type 1 (HIV-1) in infected individuals. HIV-1 infection induces production of M-CSF by macrophages, which in turn promotes further infection of macrophages via increases in CD4 and CCR5 receptors, as well as increases in virus gene expression. M-CSF promotes the ontogeny and survival of macrophages, contributing to both the number and longevity of these infected cells. M-CSF dysregulation promotes the differentiation of monocytes toward macrophages and osteoclasts and at the same time may inhibit differentiation toward dendritic cells, resulting in immune impairment. The potential role of M-CSF in HIV-associated end organ diseases including HIV-associated dementia, HIV-associated nephropathy, and osteoporosis is discussed. This review emphasizes the need for developing M-CSF antagonists for treatment of HIV-1-infected patients.

Evolving paradigms in the pathogenesis of HIV-1-associated dementia.

HIV-1-associated dementia (HIV-D) remains a significant consequence of HIV-1 infection and AIDS. Since the clinical introduction of highly active antiretroviral therapy (HAART), the incidence of HIV-D has decreased, yet the prevalence has increased as patients are living longer under treatment. Additionally, a less severe form of HIV-D, minor cognitive motor disorder, has become an increasing issue. Two different models have been proposed for virus entry in the central nervous system (CNS) in HIV-D. In the 'Trojan horse' model, the virus enters the CNS early carried by macrophages and infects resident glia; later in the course of infection, virus replication is activated and additional monocyte/macrophages are recruited into the CNS via cytokine/chemokine networks and endothelial-cell-leukocyte interactions at the blood-brain barrier. In the 'late invasion' model, an inherently invasive activated monocyte subset is expanded from bone marrow as a result of immune dysregulation in the periphery in the setting of AIDS. In this review we discuss these two separate, although not mutually exclusive, means for virus entry and persistence in the CNS. Additionally, we explore mechanisms for neuronal injury and apoptosis, including the role of virus, viral and host proteins, oxidative stress and products of infected or uninfected activated microglia and astrocytes. Potential therapeutic strategies are also briefly discussed.

Macrophage/microglial accumulation and proliferating cell nuclear antigen expression in the central nervous system in human immunodeficiency virus encephalopathy.

This study was performed to quantitate and characterize the mononuclear phagocytes (MPs) in human immunodeficiency virus encephalopathy (HIVE) by immunohistochemistry in an effort to gain insights into potential mechanisms of central nervous system (CNS) accumulation. Single- and double-labeled studies using antibodies against CD14, CD16, CD68, proliferating cell nuclear antigen (PCNA), Ki-67, von Willebrand factor, and HIV-1 p24 were performed using brain tissue from patients with HIVE, HIV-1 infection without encephalitis, and seronegative controls. A substantial increase in MPs was observed in CNS tissue from patients with HIVE, relative to seronegative controls and patients with acquired immune deficiency syndrome but without encephalitis, as determined by CD68 and CD16 immunohistochemistry. A large proportion of CD16+ MPs in HIVE CNS tissue were PCNA+, but do not appear to be proliferating, based on limited Ki-67 positivity. Although virtually all cells positive for HIV-1 p24 were PCNA+, there were many PCNA+ cells where HIV-1 p24 expression was not detected. PCNA positivity was also observed in some endothelial cells and ependymal cells in HIVE CNS. Our results would support a role for HIV-1-induced alterations in MP trafficking and homeostasis in the pathogenesis of HIVE.