Browsing by Subject "CXCL8"
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Item Chemokine CXCL8 Mediated Intercellular Interactions in HIV-1 associated Dementia(2013-12-01) Mamik, Manmeet K.; Ghorpade, AnujaThis dissertation explores the role of chemokine CXCL8 during human immune deficiency virus (HIV)-1 infection in the brain. Chemokine CXCL8 is an important neutrophil chemoattractant implicated in various neurodegenerative disorders. It is upregulated in the brains and cerebrospinal fluid of HIV-1 infected individuals suggesting its potential role in HIV-1 associated neuroinflammation. Astrocytes are known to be the major contributors to the CXCL8 pool. Interleukin (IL)-1β activated astrocytes exhibit significant upregulation of CXCL8. In order to determine the signaling pathways involved in CXCL8 regulation in astrocytes, we employed pharmacological inhibitors for non-receptor Src homology-2 domain-containing protein tyrosine phosphatase (SHP) 2 and mitogen-activated protein kinases (MAPK) pathway and observed reduced expression of CXCL8 following IL-1β stimulation. Thus, our findings suggest an important role for SHP2 in CXCL8 expression in astrocytes during inflammation, as SHP2, directly or indirectly, modulates p38 and extracellular signal regulated kinase (ERK) MAPK in the signaling cascade leading to CXCL8 production. In the post-antiretroviral therapy (ART) era, low level of productive replication of HIV-1 in brain is a critical component of neuropathogenesis regulation. HIV-1 replication is a complex mechanism involving both host and viral factors. The majority of viral replication in brain occurs in perivascular macrophages and/or 2 microglia. In this study, we investigated the effect of CXCL8 on productive infection of HIV-1 in human monocytes-derived macrophages (MDM) and primary human microglia. The results show that CXCL8 mediates productive infection of HIV-1 in MDM and microglia via receptors CXCR1 and CXCR2 and induces HIV-1 long terminal repeat (LTR) promoter activity. Detailed understanding of astrocyte signaling and HIV-1 replication, as presented in the thesis, will be relevant to glial-neuronal interactions, which are central to neuroinflammation in HIV-1 and many other neurodegenerative conditions. Also, modulation of levels of CXCL8 can be a therapeutic strategy for control of productive HIV-1 replication in the brain.Item CHEMOKINE CXCL8 MODULATES HIV-1 REPLICATION IN HUMAN MONOCYTE-DERIVED MACROPHAGES(2013-04-12) Mamik, Manmeet K.Purpose: Chemokine CXCL8 is an important neutrophil chemoattractant implicated in various neurodegenerative disorders. We previously reported that HIV-1 infection is linked to upregulation of CXCL8 in brain tissue. We also reported that SHP2 and MAPK pathways regulate the expression of CXCL8 in human astrocytes. In the post-ART era, low level of productive replication of HIV-1 in brain is a critical component of neuropathogenesis regulation. The present study investigated the effect of CXCL8 on productive infection of HIV-1 in human monocytes-derived macrophages (MDM). Methods: Human MDM were infected with blood and brain-derived HIV-1 isolates, HIVADA and HIVJR-FL. HIV p24 levels were assayed from culture supernatants with ELISA. DNA was isolated from infected cells treated with/without CXCL8 (10-100ng/ml) and amplified for two-LTR circles, as a measure of integration We employed human promonocytic cell line U937 as an efficient transfection system. U937 cells were transfected with pHIV-LTR and promoter activity was measured by luciferase reporter assay. Results: Treatment with CXCL8 led to significant upregulation (p<0.01) in HIV-1 p24 levels in supernatants of HIV-infected MDM, as determined by ELISA. Reverse transcriptase (RT) activity was significantly increased (p<0.01) in HIV-infected MDM treated with CXCL8. We compared the formation of 2-LTR circles in CXCL8 treated vs untreated HIV-infected MDM by RT-PCR, as a measure of viral genome integration. Transient transfection of U937 cells with HIV-LTR construct containing luciferase reporter gene resulted in increased luciferase activity when treated with CXCL8. Conclusions: The results show that CXCL8 mediates productive infection of HIV-1 in MDM and induces HIV-1 LTR promoter activity in U937 cells. Detailed understanding of the mechanisms involved could aid in therapeutic intervention strategies by modulating levels of this chemokine in the brain.