Defense Date


Document Type


Degree Name

Master of Science


Pharmacology & Toxicology

First Advisor

Dr. Kurt F. Hauser


About 1 in 10 newly diagnosed HIV cases in the United States are attributed to injection drug abuse. Opiate abuse exacerbates HIV disease progression in the central nervous system by disrupting glial function and significantly augmenting glial-derived pro-inflammatory mediators. Astroglia and microglia exposed to viral proteins, such as transactivator of transcription (Tat), become activated leading to release of a large number of cytokines and chemokines and a positive loop of neuro-inflammation. Despite effective antiretroviral therapy, persistent inflammation and immune activation affect HIV-infected individuals. A potential alternative target is sphingosine 1-phosphate receptor 1 (S1PR1) which is known to play a role in proliferation and trafficking of immune cells. In addition, the S1P-S1PR1 ligand-receptor axis induces NF-κB activation and pro-inflammatory cytokine production in astrocytes. The drug FTY720 (fingolimod) acts at S1PR1,3,4,5 and its therapeutic effects are thought to result from the drug’s ability to cause receptor internalization and degradation thereby acting as a functional antagonist. The purpose of this study was to assess if S1PR1 modulation by FTY720 regulates cytokine levels in the context of downstream astroglial activation induced by HIV-1 Tat ± morphine. Pretreatment of primary murine glial cultures with FTY720 results in dose-dependent inhibition of Tat±morphine induced increases in IL-6, CCL2, CCL3, and CCL4 levels. A selective 1 antagonist, W146, blocked these increases providing evidence that indeed the significant reduction in cytokine levels was mediated through S1PR1. In comparison SEW 2871, a S1PR1 agonist that leads to receptor recycling upon internalization instead of ubiquitination/degradation, was used to examine if receptor downregulation is responsible for attenuated cytokine release. Glia that were pretreated with SEW 2871 for a shorter duration prior to treatment with Tat or morphine displayed time-dependent reduction in cytokine secretion. Contrastingly, cells pre-exposed to SEW 2871 for a longer period demonstrated elevated protein levels, suggesting the differential fate of receptor after internalization is involved in regulating the inflammatory response.


© Jean Moon

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