HIV-1 and IL-1β regulate astrocytic CD38 through mitogen-activated protein kinases and nuclear factor-κB signaling mechanisms

Manmeet K. Mamik, Sugato Banerjee, Timothy F. Walseth, Renee Hirte, Lin Tang, Kathleen Borgmann, Anuja Ghorpade

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Background: Infection with human immunodeficiency virus type-1 (HIV)-1 leads to some form of HIV-1-associated neurocognitive disorders (HAND) in approximately half of the cases. The mechanisms by which astrocytes contribute to HIV-1-associated dementia (HAD), the most severe form of HAND, still remain unresolved. HIV-1-encephalitis (HIVE), a pathological correlate of HAD, affects an estimated 9-11% of the HIV-1-infected population. Our laboratory has previously demonstrated that HIVE brain tissues show significant upregulation of CD38, an enzyme involved in calcium signaling, in astrocytes. We also reported an increase in CD38 expression in interleukin (IL)-1β-activated astrocytes. In the present investigation, we studied regulatory mechanisms of CD38 gene expression in astrocytes activated with HIV-1-relevant stimuli. We also investigated the role of mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-κB in astrocyte CD38 regulation.Methods: Cultured human astrocytes were transfected with HIV-1 YU-2 proviral clone and levels of CD38 mRNA and protein were measured by real-time PCR gene expression assay, western blot analysis and immunostaining. Astrocyte activation by viral transfection was determined by analyzing proinflammatory chemokine levels using ELISA. To evaluate the roles of MAPKs and NF-κB in CD38 regulation, astrocytes were treated with MAPK inhibitors (SB203580, SP600125, U0126), NF-κB interfering peptide (SN50) or transfected with dominant negative IκBα mutant (IκBαM) prior to IL-1β activation. CD38 gene expression and CD38 ADP-ribosyl cyclase activity assays were performed to analyze alterations in CD38 levels and function, respectively.Results: HIV-1 YU-2-transfection significantly increased CD38 mRNA and protein expression in astrocytes (p < 0.01) in a dose-dependent manner and induced astrocyte activation. IL-β-activation of HIV-1 YU-2-transfected astrocytes significantly increased HIV-1 gene expression (p < 0.001). Treatment with MAPK inhibitors or NF-κB inhibitor SN50 abrogated IL-1β-induced CD38 expression and activity in astrocytes without altering basal CD38 levels (p < 0.001). IκBαM transfection also significantly inhibited IL-1β-mediated increases in CD38 expression and activity in astrocytes (p < 0.001).Conclusion: The present findings demonstrate a direct involvement of HIV-1 and virus-induced proinflammatory stimuli in regulating astrocyte-CD38 levels. HIV-1 YU-2-transfection effectively induced HIV-1p24 protein expression and activated astrocytes to upregulate CCL2, CXCL8 and CD38. In astrocytes, IL-1β-induced increases in CD38 levels were regulated through the MAPK signaling pathway and by the transcription factor NF-κB. Future studies may be directed towards understanding the role of CD38 in response to infection and thus its role in HAND.

Original languageEnglish (US)
Article number145
JournalJournal of Neuroinflammation
StatePublished - Oct 25 2011

Bibliographical note

Funding Information:
This study was supported by grants from the NINDS, RO1 NS43113 and NIMH, MH087345 to A. Ghorpade. We also appreciate the support of the Laboratory of Developmental Biology for providing us with human brain tissues. The project entitled “Laboratory of Developmental Biology” was supported by NIH Award Number 5R24HD0008836 from the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD). The content does not necessarily represent the official views of the NICHD of the NIH.


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