Original Contribution
HIV proteins (gp120 and Tat) and methamphetamine in oxidative stress-induced damage in the brain: Potential role of the thiol antioxidant N-acetylcysteine amide

https://doi.org/10.1016/j.freeradbiomed.2010.02.023Get rights and content

Abstract

An increased risk of HIV-1 associated dementia (HAD) has been observed in patients abusing methamphetamine (METH). Since both HIV viral proteins (gp120, Tat) and METH induce oxidative stress, drug abusing patients are at a greater risk of oxidative stress-induced damage. The objective of this study was to determine if N-acetylcysteine amide (NACA) protects the blood brain barrier (BBB) from oxidative stress-induced damage in animals exposed to gp120, Tat and METH. To study this, CD-1 mice pre-treated with NACA/saline, received injections of gp120, Tat, gp120 + Tat or saline for 5 days, followed by three injections of METH/saline on the fifth day, and sacrificed 24 h after the final injection. Various oxidative stress parameters were measured, and animals treated with gp120 + Tat + Meth were found to be the most challenged group, as indicated by their GSH and MDA levels. Treatment with NACA significantly rescued the animals from oxidative stress. Further, NACA-treated animals had significantly higher expression of TJ proteins and BBB permeability as compared to the group treated with gp120 + Tat + METH alone, indicating that NACA can protect the BBB from oxidative stress-induced damage in gp120, Tat and METH exposed animals, and thus could be a viable therapeutic option for patients with HAD.

Introduction

HIV-1-associated-dementia (HAD), a neurological syndrome characterized by cognitive deficits and motor and behavioral dysfunctions, is one of the most common complications associated with human immunodeficiency virus (HIV-1) infection [1], [2], [3], [4]. A third of the adults and half of the children with HIV infection have been reported to develop HAD [5]. HAD is one of the most common causes of dementia worldwide among people aged 40 years or less, and is a significant independent risk factor in death due to HIV infection [6]. Though the clinical and pathological conditions of HAD have been well characterized, the pathogenesis of the progression of the disease is not well understood.

The blood-brain barrier (BBB), defining an interface between the central nervous system and the blood, performs the essential function of shielding the brain from toxic substances and is believed to play an important role in the development of HAD [7], [8]. Studies have shown that disruption of the BBB is more frequent in HAD patients when compared with non-demented HIV patients or control patients [9]. Furthermore, the HIV-1 envelope glycoprotein (gp120) and transregulatory protein (Tat) of HIV-1 are neurotoxic and cytotoxic and have been implicated in the development of HAD [10], [11]. Previous studies have reported that oxidative stress-induced by gp120 and Tat leads to the disruption of the BBB [12]. A dose-dependent increase in oxidative stress and decrease in intracellular glutathione have been observed in brain endothelial cells treated with Tat [9].

In addition to this, many HIV-positive patients use addictive drugs like methamphetamine (METH), which is a well known neurotoxicant [13], [14], [15]. METH has been reported to promote dopamine release in the nucleus accumbens, leading to degeneration of the striatal dopamine terminals [16], [17]. Further, dopamine oxidation leads to the formation of reactive oxygen species, which disturbs the antioxidant defense mechanism in the body leading to oxidative stress-induced damage [18]. Overproduction of superoxide radicals and a decrease in antioxidant enzyme activity have been observed in mice treated with METH. Degeneration of various regions of the brain, particularly the BBB, has also been reported due to METH abuse. Brain degeneration is associated with modifications of the BBB [19]. Disruption of the tight junctions (TJ) is one of the common causes of BBB dysfunction. TJs are composed of the tight junction proteins (Occludin, Claudin, Zona Occludens), and play an important role in maintaining the structural integrity and low permeability of the BBB [20]. Disruption of the BBB has been reported to contribute to the progression of various neurological diseases like multiple sclerosis, Alzheimer's and Parkinson's disease [21]. Further, oxidative stress has also been reported to be an important factor in BBB dysfunction [22]. Under physiological conditions, the integrity of the BBB is protected from oxidative stress because the BBB has high levels of antioxidant enzymes. However, under oxidative stress, depletion of these antioxidant enzymes leads to the increase in permeability and loss of integrity of these endothelial cells [23]. Supplementation of antioxidants is becoming increasingly popular in oxidative stress-related disorders. Thiol antioxidants like cysteine, glutathione and N-acetylcysteine (NAC) have been shown to provide a protective effect against stress-related disorders [24], [25], [26], [27]. However, some of these thiols, such as NAC, have been reported to have several side effects and toxicities such as suppressing respiratory burst, and causing toxic accumulation of ammonia in the liver [28], [29]. In addition, bioavailability of NAC is very low because its carboxylic group loses its proton at physiological pH, making the compound negatively charged and consequently less permeable. N-acetylcysteine amide (NACA), a modified form of NAC, where the carboxyl group has been replaced by an amide group, has been found to be more effective in neurotoxic cases because of its ability to permeate cell membranes and the BBB [29].

Since METH has been shown to induce oxidative stress, it was of significant interest to understand if METH potentiated the oxidative stress induced by HIV-1 proteins gp120 and Tat at the BBB. Also, the efficacy of the thiol antioxidant NACA to confer protection to animals exposed to gp120, Tat and METH, and to abrogate the oxidative stress-induced damage at the BBB was investigated.

Section snippets

Materials

CD-1 mice were obtained from the in-house colony at the VA medical center-St. Louis. N-acetylcysteine amide (NACA) was provided by Dr. Glenn Goldstein (David Pharmaceuticals, New York, NY, USA). N-(1-pyrenyl)-maleimide (NPM) was purchased from Sigma (St. Louis, MO). High-performance liquid chromatography (HPLC) grade solvents were purchased from Fisher Scientific (Fair Lawn, NJ). All other chemicals were purchased from Sigma (St. Louis, MO), unless stated otherwise.

Animal experiments

Male CD-1 mice (30-35 g, 7 

Effects of HIV proteins, METH and NACA on GSH levels in the brain

The effects of HIV proteins gp120 and Tat in the brain were studied. Compared to the controls and the NACA-alone treated group, the gp120- and METH-treated animals had decreases (∼ 20%) in the GSH levels in their brains. A significant and drastic decrease (∼ 85%) in the levels of GSH was observed in animals treated with Tat protein alone. In this study, animals treated with gp120 + Tat and gp120 + Tat + METH, also experiences significant decrease in GSH levels, as compared to the controls or the

Discussion

In the recent years, METH use has been implicated in worsening of HIV associated neurological impairments, especially HAD [43], [44], [45], [46], [47]. The neurotoxic effect of METH increases dopamine and glutamate formation in the brain that, in turn, mediates damage to the dopamine neurons through the formation of toxic ROS [48], [49], [50], [51]. The HIV viral proteins (gp120 and Tat) have also been reported to increase oxidative stress in the brain [12]. Although both HIV viral proteins and

Acknowledgments

Dr. Ercal is supported by 1 R15DA023409-01A2 from the NIDA, NIH. The contents of this paper are solely the responsibility of the authors and do not necessarily represent official views of the NIDA or NIH. Dr. Banks is supported by VA Merit Review and R01 AG029839. The authors appreciate the efforts of Barbara Harris in editing the manuscript. HIV-1 Tat and HIV-1 Bal gp120 protein was obtained through the NIH AIDS Research and Reference Reagent Program, Division of AIDS, NIAID, NIH.

References (98)

  • R. Winters et al.

    Analysis of glutathione, glutathione disulphide, cysteine, homocysteine and other biological thiols by HPLC following derivatization with N-(1-pyrenyl) malemide

    Anal. Biochem.

    (1995)
  • H.H. Draper et al.

    A comparative evaluation of thiobarbituric acid methods for the determination of malondialdehyde in biological materials

    Free Radic. Biol. Med.

    (1993)
  • I. Dalle-Donne et al.

    Protein carbonyl groups as biomarkers of oxidative stress

    Clin. Chim. Acta

    (2003)
  • M.M. Bradford

    A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein–dye binding

    Anal. Biochem.

    (1976)
  • G. Lenzser et al.

    Diazoxide preconditioning attenuates global cerebral ischemia-induced blood-brain barrier permeability

    Brain Res.

    (2005)
  • C. Davidson et al.

    Methamphetamine neurotoxicity: necrotic and apoptotic mechanisms and relevance to human abuse and treatment

    Brain Res. Brain Res. Rev.

    (2001)
  • R. Dringen

    Metabolism and functions of glutathione in brain

    Prog. Neurobiol.

    (2000)
  • M. Gu et al.

    Mitochondrial function, GSH and iron in neurodegeneration and Lewy body diseases

    J. Neurol. Sci.

    (1998)
  • E. Sofic et al.

    Reduced and oxidized glutathione in the substantia nigra of patients with Parkinson's disease

    Neurosci. Lett.

    (1992)
  • X. Zhang et al.

    N-acetylcysteineamide protects against methamphetamine-induced oxidative stress and neurotoxicity in immortalized brain endothelial cells

    Brain Res.

    (2009)
  • K. Mertsch et al.

    4-hydroxynonenal impairs the permeability of an in vivo rat blood-brain barrier

    Neurosci. Lett.

    (2001)
  • M. Chavko et al.

    Regional lipid peroxidation and protein oxidation in rat brain after hyperbaric oxygen exposure

    Free Radic. Biol. Med.

    (1996)
  • G. Perry et al.

    How important is oxidative damage? Lessons from Alzheimer's disease

    Free Radic. Biol. Med.

    (2000)
  • K.J. Davies et al.

    Proteins damaged in extracts of red blood cells

    J. Biol. Chem.

    (1987)
  • A.J. Rivett et al.

    Metal-catalyzed oxidation of Escherichia coli glutamine synthetase: correlation of structural and functional changes

    Arch. Biochem. Biophys.

    (1990)
  • M.Y. Aksenov et al.

    Protein oxidation in the brain in Alzheimer's disease

    Neuroscience

    (2001)
  • S. Theodore et al.

    Inhibition of tumor necrosis factor-alpha signaling prevents human immunodeficiency virus-1 protein Tat and methamphetamine interaction

    Neurobiol. Dis.

    (2006)
  • S. Theodore et al.

    Involvement of cytokines in human immunodeficiency virus-1 protein Tat and Methamphetamine interactions in the striatum

    Exp. Neurol.

    (2006)
  • S. Theodore et al.

    Methamphetamine and human immunodeficiency virus protein Tat synergize to destroy dopaminergic terminals in the rat striatum

    Neuroscience

    (2006)
  • L.M. Dallasta et al.

    Blood–brain barrier tight junction disruption in human immunodeficiency virus-1 encephalitis

    Am. J. Pathol.

    (1999)
  • Y. Persidsky et al.

    Rho-mediated regulation of tight junctions during monocyte migration across the blood-brain barrier in HIV-1 encephalitis (HIVE)

    Blood

    (2006)
  • A. Hammer et al.

    Effect of oxidative stress by iron on 4-hydroxynonenal formation and proliferative sctivity in hepatomas of different degrees of differentiation

    Free Radic. Biol. Med.

    (1997)
  • P.V. Usatyuk et al.

    Redox regulation of 4-hydroxy-2-nonenal mediated endothelial barrier dysfunction by focal adhesion, adherens and tight junction proteins

    J. Biol. Chem.

    (2006)
  • P.V. Usatyuk et al.

    Role of mitogen-activated protein kinases in 4-hydroxy-2-nonenal-induced actin remodeling and barrier function in endothelial cells

    J. Biol. Chem.

    (2004)
  • K. Uchida et al.

    Activation of stress signaling pathways by the end product of lipid peroxidation. 4-hydroxy-2-nonenal is a potential producer of intracellulaqr peroxide production

    J. Biol. Chem.

    (1999)
  • K. Mertsch et al.

    4-Hydroxynonenal impairs the permeability of an in vitro rat blood brain barrier

    Neurosci. Lett.

    (2001)
  • A.H. Cross et al.

    Peroxynitrite formation within the central nervous system in active multiple sclerosis

    J. Neuroimmunol.

    (1998)
  • H.E. Gendelman et al.

    The neuropathogenesis of the AIDS dementia complex

    AIDS

    (1997)
  • A. Nath

    Human immunodeficiency virus (HIV) proteins in neuropathogenesis of HIV dementia

    J. Infect. Dis.

    (2002)
  • M. Kaul et al.

    Pathways to neuronal injury and apoptosis in HIV-associated dementia

    Nature

    (2001)
  • W.A. Banks

    Physiology and pathophysiology of the blood–brain barrier: implications for microbial pathogenesis, drug delivery and neurodegenerative disorders

    J. Neurovirol.

    (1999)
  • Y. Persidsky et al.

    A model for monocyte migration through the blood–brain barrier during HIV-1 encephalitis

    J. Immunol.

    (1997)
  • M. Toborek et al.

    HIV-Tat protein induces oxidative and inflammatory pathways in brain endothelium

    J. Neurochem.

    (2003)
  • W. Li et al.

    Molecular and cellular mechanisms of neuronal cell death in HIV dementia

    Neurotox. Res.

    (2005)
  • A. Nath et al.

    Neurotoxicity and dysfunction of dopaminergic systems associated with AIDS dementia

    J. Psychopharmacol.

    (2000)
  • B.T. Hawkins et al.

    The blood-brain barrier/neurovascular unit in health and disease

    Pharmacol. Rev.

    (2005)
  • B.M. Denker et al.

    Molecular structure and assembly of the tight junction

    Am. J. Physiol. Renal. Physiol.

    (1998)
  • M.W. Bradbury

    The blood-brain barrier

    Exp. Physiol.

    (1993)
  • A. Cho

    Ice: a new dosage form of an old drug

    Science

    (1990)
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