Raghava Potula, Ph.D, MHA - US grants

[unreadable] DESCRIPTION (provided by applicant): Illicit drugs such as methamphetamine (METH) alter immune functions and decreases host resistance. There is an association between METH abuse and enhanced susceptibility to infections; however, underlying mechanisms are largely unknown. High incidence of HIV-1 infection in METH abusers and potential effects of METH on immune system underscore clinical significance of METH-HIV-1 co-morbidity. Defective immune responses could lead to the accelerated HIV-1 infection in the peripheral organs and central nervous system (CNS). Preliminary data point to the oxidative stress as one of possible causes of METH induced immune dysfunction. Indeed, our preliminary studies indicate that METH exposure elicits oxidative stress in T cells and upon T-cell receptor stimulation show T cell proliferation and decreases cytokine production. T cells exposed to METH demonstrate modulation of genes controlling in immune cell activation and T cell surface markers. Therefore, we hypothesize that the oxidative stress caused by METH in T lymphocytes dampens immune responses, impairs T cell activation and proliferation leading to enhanced progression of HIV-1 infection. Using a combination of in vitro systems and animal model for HIV-1 encephalitis chronically exposed to METH, we will address the following questions: (1) What are the potential implications of METH- induced oxidative stress on T cell functions? (2) What are the mechanisms underlying impaired T cell immune responses mediated by oxidative stress associated with METH? (3) How does T cell dysfunction affect the adaptive immune system responses to HIV-1 infection in and outside of CNS? Antioxidants and specific signaling inhibitors will be utilized to delineate pathways involved in these effects. We believe that the proposed works are highly significant as they will uncover novel mechanisms mediating combined effects of HIV-1 and METH abuse on immunity and propose therapeutic approaches based on these investigations. PUBLIC HEALTH RELEVANCE Methamphetamine is a highly addictive stimulant abused by millions of Americans and is known to alter immune function and increase susceptibility to infection. Epidemiological studies indicate growing evidence of the association between METH abuse and an increased incidence of HIV-1 infections. However, the apparent causal interrelationship between METH abuse and susceptibility to HIV-1 infection or its progression are largely unknown. This proposal aims to understand putative mechanisms of immune dysfunctions in the setting of METH abuse and HIV-1 infection. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Methamphetamine (METH) abuse impairs host defense mechanisms and is thought to enhance host susceptibility to infections. High incidence of HIV-1 infection in METH abusers and potential effects of METH on the immune system underscore the clinical significance of METH-HIV-1 co-morbidity. Although METH abuse is implicated in dysregulation of immunity, the causal interrelationship between METH exposure and the inability to elicit protective adaptive immune response remains elusive. Acquired immunity, in particular CD8+T cell response, plays a pivotal role in control of HIV-1 infection. Lack of understanding of impact of METH abuse on acquired immune response in controlling HIV-1 infection warrants future considerations. Our preliminary data showed that METH exposure increased cytosolic calcium levels in primary human T cells leading to generation of ROS that correlated with mitochondrial injury and T cell dysfunction. We found that METH exposure altered gene expression regulating cell signaling, proliferation and differentiation, cell-mediated immune responses and transcriptional co-activation potentially contributing to METH-mediated T cell dysfunction. For the first time, we showed that trace amine associated receptor (TAAR1, a novel receptor activated by amines) is stimulated by METH on T cells implying that some of METH effects may be attributable to activity of this receptor. Using a combination of in vitro (molecular, biochemical and functional assays) and in vivo animal models of chronic viral infection (SCID mouse model for HIV-1 encephalitis and LCMV mouse model) chronically exposed to METH, we will address the following questions: (1) What are the pathophysiological effects of METH on T cell mitochondrial dynamics? (2) What are the underlying mechanisms and molecular consequences of METH-mediated mitochondrial dysfunction on T cells and what roles do they play in cell immune cell impairment? (3) What effects does METH-mediated immune dysfunction have on the host adaptive immune responses to chronic viral infections (HIV-1/LCMV infection)? We will identify mitochondrial substrates of METH and delineate pathways involved in these effects by using proteomic and molecular biological approaches. The proposed work is highly significant, as it will contribute to understanding of the underlying mechanisms of the combined effects of HIV-1 and METH abuse on adaptive immunity. Therapeutic approaches towards boosting T cell immunity based on these investigations will reduce persistent infection. PUBLIC HEALTH RELEVANCE: Methamphetamine, a highly addictive stimulant abused by millions of Americans and is known to alter immune function and increase susceptibility to infection. Epidemiological studies indicate growing evidence of the association between METH abuse and an increased incidence of HIV-1 infections. However, the apparent causal interrelationship between METH abuse and susceptibility to HIV-1 infection or its progression are largely unknown. Current proposal aims to understand putative mechanisms of immune dysfunctions in the setting of METH abuse and HIV-1 infection.

Treatment of HIV-infected patients with antiretroviral therapy (ART) has effectively suppressed viral replication; however, the central nervous system (CNS) is still a major target and reservoir of the virus leading to the development of HIV-1-associated neurocognitive disorders (HAND). Importantly, since the beginning of the HIV epidemic, drug use has remained a primary risk factor for contracting, transmitting, and worsening the outcomes of HIV. In fact, regarding pathogenesis, psychostimulants can induce higher viral loads, reduce CD4 counts, and increase rates of ART resistance. Furthermore, neuropsychological decline is greater in individuals that are cocaine users and HIV-seropositive. Extracellular microvesicles (EVs), which includes microvesicles (MVs) and exosomes, have emerged as a novel biological phenomenon, released by virtually every cell type in the body. We have shown that brain microvasculature endothelial cell (BMVEC)-derived EVs contain tight junction proteins (TJPs) and transporter proteins, which are main constituents of the BBB. Furthermore, a hallmark feature of HAND is the disruption of the BBB and loss of TJ complexes. In this proposal, we show that BMVECs shed EVs in response to HIV virotoxins and psychostimulants. Thus, we hypothesize that HIV infection and/or drugs of abuse triggers EV release leading to BBB instability and facilitation of neuroinvasion by infected immune cells. The innovative nature of this proposal is featured in three independent aims. In the first aim, we will characterize the degree of EV production (MVs and exosomes) as a function of psychostimulant type using a novel microfluidic model of the neurovascular unit with primary human cells. We will also investigate the effects of exposure to HIV virotoxins and ART pharmacologic agents on BMVEC-EV production. Furthermore, we will correlate EC-EV release to the phases of addiction in an in-vivo self-administration model as well as in a humanized mouse model of HIV infection with or without drug administration. In the second aim, we introduce the novel concept that BMVEC-derived EVs bind to activated or infected monocytes, which triggers increased monocytic transendothelial migration. Thus, we hypothesize that monocytes utilize TJPs on EVs to engage endothelial tight junction complexes and facilitate immune infiltration of the CNS. In the third aim, we will explore a therapeutic strategy that could minimize EV production and thus rescue BBB integrity. The above will be accomplished by targeted inhibition of ARF6, which is involved in MV and exosome biogenesis. Using new pharmacological tools to inhibit ARF6, we aim to stabilize the BBB to prevent BBB barrier dysfunction during neuroinflammation. The studies proposed herein will offer crucial insight to brain endothelial EV production, mechanisms of immune cell infiltration into the CNS, and also reveal targets for pharmacological interventions that promote BBB protection in HIV and substance use disorder.