Molecular mechanism of decreased glutathione content in human immunodeficiency virus type 1 Tat-transgenic mice

Heterogeneous Oxidation Products of Fine Particulate Isoprene Epoxydiol-Derived Methyltetrol Sulfates Increase Oxidative Stress and Inflammatory Gene Responses in Human Lung Cells

Hydroxyl radical (·OH)-initiated oxidation of isoprene, the most abundant nonmethane hydrocarbon in the atmosphere, is responsible for substantial amounts of secondary organic aerosol (SOA) within ambient fine particles. Fine particulate 2-methyltetrol sulfate diastereoisomers (2-MTSs) are abundant SOA products formed via acid-catalyzed multiphase chemistry of isoprene-derived epoxydiols with inorganic sulfate aerosols under low-nitric oxide conditions. We recently demonstrated that heterogeneous ·OH oxidation of particulate 2-MTSs leads to the particle-phase formation of multifunctional organosulfates (OSs). However, it remains uncertain if atmospheric chemical aging of particulate 2-MTSs induces toxic effects within human lung cells. We show that inhibitory concentration-50 (IC50) values decreased from exposure to fine particulate 2-MTSs that were heterogeneously aged for 0 to 22 days by ·OH, indicating increased particulate toxicity in BEAS-2B lung cells. Lung cells further exhibited concentration-dependent modulation of oxidative stress- and inflammatory-related gene expression. Principal component analysis was carried out on the chemical mixtures and revealed positive correlations between exposure to aged multifunctional OSs and altered expression of targeted genes. Exposure to particulate 2-MTSs alone was associated with an altered expression of antireactive oxygen species (ROS)-related genes (NQO-1, SOD-2, and CAT) indicative of a response to ROS in the cells. Increased aging of particulate 2-MTSs by ·OH exposure was associated with an increased expression of glutathione pathway-related genes (GCLM and GCLC) and an anti-inflammatory gene (IL-10).

A truncated HIV Tat demonstrates potent and specific latency reversal activity

A major barrier to HIV-1 cure is caused by the pool of latently infected CD4 T-cells that persist under combination antiretroviral therapy (cART). This latent reservoir is capable of producing replication-competent infectious viruses once prolonged suppressive cART is withdrawn. Inducing the reactivation of HIV-1 gene expression in T-cells harboring a latent provirus in people living with HIV-1 under cART may result in depletion of this latent reservoir due to cytopathic effects or immune clearance. Studies have investigated molecules that reactivate HIV-1 gene expression, but to date, no latency reversal agent has been identified to eliminate latently infected cells harboring replication-competent HIV in cART-treated individuals. Stochastic fluctuations in HIV-1 tat gene expression have been described and hypothesized to allow the progression into proviral latency. We hypothesized that exposing latently infected CD4+ T-cells to Tat would result in effective latency reversal. Our results indicate the capacity of a truncated Tat protein and mRNA to reactivate HIV-1 in latently infected T-cells ex vivo to a similar degree as the protein kinase C agonist: phorbol 12-myristate 13-acetate, without T-cell activation or any significant transcriptome perturbation.

Heme-Induced Macrophage Phenotype Switching and Impaired Endogenous Opioid Homeostasis Correlate with Chronic Widespread Pain in HIV

Chronic widespread pain (CWP) is associated with a high rate of disability and decreased quality of life in people with HIV-1 (PWH). We previously showed that PWH with CWP have increased hemolysis and elevated plasma levels of cell-free heme, which correlate with low endogenous opioid levels in leukocytes. Further, we demonstrated that cell-free heme impairs β-endorphin synthesis/release from leukocytes. However, the cellular mechanisms by which heme dampens β-endorphin production are inconclusive. The current hypothesis is that heme-dependent TLR4 activation and macrophage polarization to the M1 phenotype mediate this phenomenon. Our novel findings showed that PWH with CWP have elevated M1-specific macrophage chemokines (ENA-78, GRO-α, and IP-10) in plasma. In vitro, hemin-induced polarization of M0 and M2 macrophages to the M1 phenotype with low β-endorphins was mitigated by treating cells with the TLR4 inhibitor, TAK-242. Similarly, in vivo phenylhydrazine hydrochloride (PHZ), an inducer of hemolysis, injected into C57Bl/6 mice increased the M1/M2 cell ratio and reduced β-endorphin levels. However, treating these animals with the heme-scavenging protein hemopexin (Hx) or TAK-242 reduced the M1/M2 ratio and increased β-endorphins. Furthermore, Hx attenuated heme-induced mechanical, heat, and cold hypersensitivity, while TAK-242 abrogated hypersensitivity to mechanical and heat stimuli. Overall, these results suggest that heme-mediated TLR4 activation and M1 polarization of macrophages correlate with impaired endogenous opioid homeostasis and hypersensitivity in people with HIV.

Involvement of TRPM7 in Alcohol-Induced Damage of the Blood-Brain Barrier in the Presence of HIV Viral Proteins

Ethanol (EtOH) exerts its effects through various protein targets, including transient receptor potential melastatin 7 (TRPM7) channels, which play an essential role in cellular homeostasis. We demonstrated that TRPM7 is expressed in rat brain microvascular endothelial cells (rBMVECs), the major cellular component of the blood-brain barrier (BBB). Heavy alcohol drinking is often associated with HIV infection, however mechanisms underlying alcohol-induced BBB damage and HIV proteins, are not fully understood. We utilized the HIV-1 transgenic (HIV-1Tg) rat to mimic HIV-1 patients on combination anti-retroviral therapy (cART) and demonstrated TRPM7 expression in rBMVECs wass lower in adolescent HIV-1Tg rats compared to control animals, however control and HIV-1Tg rats expressed similar levels at 9 weeks, indicating persistent presence of HIV-1 proteins delayed TRPM7 expression. Binge exposure to EtOH (binge EtOH) decreased TRPM7 expression in control rBMVECs in a concentration-dependent manner, and abolished TRPM7 expression in HIV-1Tg rats. In human BMVECs (hBMVECs), TRPM7 expression was downregulated after treatment with EtOH, HIV-1 proteins, and in combination. Next, we constructed in vitro BBB models using BMVECs and found TRPM7 antagonists enhanced EtOH-mediated BBB integrity changes. Our study demonstrated alcohol decreased TRPM7 expression, whereby TRPM7 could be involved in the mechanisms underlying BBB alcohol-induced damage in HIV-1 patients on cART.

HIV-1 Tat Upregulates the Receptor for Advanced Glycation End Products and Superoxide Dismutase-2 in the Heart of Transgenic Mice

Cardiovascular disorder (CVD) is a common comorbidity in people living with HIV (PLWH). Although the underlying mechanisms are unknown, virotoxic HIV proteins, such as the trans-activator of transcription (Tat), likely contribute to CVD pathogenesis. Tat expression in mouse myocardium has been found to induce cardiac dysfunction and increase markers of endothelial toxicity. However, the role that Tat may play in the development of CVD pathogenesis is unclear. The capacity for Tat to impact cardiac function was assessed using AC16 human cardiomyocyte cells and adult male and female transgenic mice that conditionally expressed Tat [Tat(+)], or did not [Tat(-)]. In AC16 cardiomyocytes, Tat increased intracellular calcium. In Tat(+) mice, Tat expression was detected in both atrial and ventricular heart tissue. Tat(+) mice demonstrated an increased expression of the receptor for advanced glycation end products and superoxide dismutase-2 (SOD-2) in ventricular tissues compared to Tat(-) controls. No changes in SOD-1 or α-smooth muscle actin were observed. Despite Tat-mediated changes at the cellular level, no changes in echocardiographic measures were detected. Tat(+) mice had a greater proportion of ventricular mast cells and collagen; however, doxycycline exposure offset the latter effect. These data suggest that Tat exposure promotes cellular changes that can precede progression to CVD.

DNA Hypomethylation of the MPO Gene in Peripheral Blood Leukocytes Is Associated with Cerebral Stroke in the Acute Phase

Dysregulation of the oxidant-antioxidant system contributes to the pathogenesis of cerebral stroke (CS). Epigenetic changes of redox homeostasis genes, such as glutamate-cysteine ligase (GCLM), glutathione-S-transferase-P1 (GSTP1), thioredoxin reductase 1 (TXNRD1), and myeloperoxidase (MPO), may be biomarkers of CS. In this study, we assessed the association of DNA methylation levels of these genes with CS and clinical features of CS. We quantitatively analyzed DNA methylation patterns in the promoter or regulatory regions of 4 genes (GCLM, GSTP1, TXNRD1, and MPO) in peripheral blood leukocytes of 59 patients with CS in the acute phase and in 83 relatively healthy individuals (controls) without cardiovascular and cerebrovascular diseases. We found that in both groups, the methylation level of CpG sites in genes TXNRD1 and GSTP1 was ≤ 5%. Lower methylation levels were registered at a CpG site (chr1:94,374,293, GRCh37 [hg19]) in GCLM in patients with ischemic stroke compared with the control group (9% [7%; 11.6%] (median and interquartile range) versus 14.7% [10.4%; 23%], respectively, p < 0.05). In the leukocytes of patients with CS, the methylation level of CpG sites in the analyzed region of MPO (chr17:56,356,470, GRCh3 [hg19]) on average was significantly lower (23.5% [19.3%; 26.7%]) than that in the control group (35.6% [30.4%; 42.6%], p < 0.05). We also found increased methylation of MPO in smokers with CS (27.2% [23.5%; 31.1%]) compared with nonsmokers with CS (21.7% [18.1%; 24.8%]). Thus, hypomethylation of CpG sites in GCLM and MPO in blood leukocytes is associated with CS in the acute phase.

Glutamine metabolite α-ketoglutarate acts as an epigenetic co-factor to interfere with osteoclast differentiation

Osteoclasts (OCs) have been well-known involved in the exacerbation of bone-related diseases. However, the role of metabolites on osteoclastogenesis has not been well characterized. Herein, we found osteoclastogenesis was negatively regulated by α-ketoglutarate (αKG) in vitro and in vivo (C57BL/6 mouse). Kinetic transcriptome analysis revealed the upregulation of solute carrier family 7 member 11 (Slc7a11), a subunit of the cysteine/glutamate antiporter, as well as the downregulation of typical OC maker genes through αKG treatment. Given that Slc7a11 could control ROS level through glutathione import, we measured intracellular ROS, then RANKL-induced ROS production was inhibited by αKG. Notably, we highlight that αKG plays an epigenetic co-factor at the Slc7a11 promoter by demethylating repressive histone H3K9 methylation and simultaneously increasing the nuclear factor erythroid 2-related factor (Nrf2) binding, a critical transcription factor through chromatin immunoprecipitation (ChIP) analysis. Together, we suggested that αKG could be a therapeutic strategy for OC activated diseases.

Intracellular Redox-Modulated Pathways as Targets for Effective Approaches in the Treatment of Viral Infection

Host-directed therapy using drugs that target cellular pathways required for virus lifecycle or its clearance might represent an effective approach for treating infectious diseases. Changes in redox homeostasis, including intracellular glutathione (GSH) depletion, are one of the key events that favor virus replication and contribute to the pathogenesis of virus-induced disease. Redox homeostasis has an important role in maintaining an appropriate Th1/Th2 balance, which is necessary to mount an effective immune response against viral infection and to avoid excessive inflammatory responses. It is known that excessive production of reactive oxygen species (ROS) induced by viral infection activates nuclear factor (NF)-kB, which orchestrates the expression of viral and host genes involved in the viral replication and inflammatory response. Moreover, redox-regulated protein disulfide isomerase (PDI) chaperones have an essential role in catalyzing formation of disulfide bonds in viral proteins. This review aims at describing the role of GSH in modulating redox sensitive pathways, in particular that mediated by NF-kB, and PDI activity. The second part of the review discusses the effectiveness of GSH-boosting molecules as broad-spectrum antivirals acting in a multifaceted way that includes the modulation of immune and inflammatory responses.

Pathogenesis of Human Immunodeficiency Virus-Mycobacterium tuberculosis Co-Infection

Given that infection with Mycobacterium tuberculosis (Mtb) is the leading cause of death amongst individuals living with HIV, understanding the complex mechanisms by which Mtb exacerbates HIV infection may lead to improved treatment options or adjuvant therapies. While it is well-understood how HIV compromises the immune system and leaves the host vulnerable to opportunistic infections such as Mtb, less is known about the interplay of disease once active Mtb is established. This review explores how glutathione (GSH) depletion, T cell exhaustion, granuloma formation, and TNF-α upregulation, as a result of Mtb infection, leads to an increase in HIV disease severity. This review also examines the difficulties of treating coinfected patients and suggests further research on the clinical use of GSH supplementation.

Glutathione, glutathione peroxidase and some hematological parameters of HIV-seropositive subjects attending clinic in University of Calabar teaching hospital, Calabar, Nigeria

BACKGROUND

Despite the numerous intervention programmes, HIV still remains a public health concern with a high impact in Sub-Saharan Africa region. Oxidative stress has been documented in HIV subjects as viral infection promotes prolonged activation of immune system, hence, production of increased reactive oxygen species.

METHODS

We studied 180 subjects. Of these, 60 were HIV-infected on antiretroviral therapy (ART), 40 were ART naïve HIV-infected and 80 were apparent healthy non HIV-infected subjects. The complete blood count was performed by automated hemoanalyzer, the CD4⁺ T-cell count was performed by cyflow cytometer, while the antioxidant assay was performed using ELISA technique.

RESULT

All evaluated parameters; glutathione (GSH), glutathione peroxidase (GPX), CD4⁺ T-cell count, haemoglobin (Hb), total white blood cell count (WBC) and platelet count were significantly (P < 0.05) reduced in the HIV-infected subjects. All assessed parameters were found to be significantly (P < 0.5) reduced in the HIV-infected subjects that are ART naive when compared with those on ART. HIV-infected subjects with CD4⁺ T-cell count < 200 cells/mm³ had significantly (P < 0.05) reduced values in all assessed parameters when compared to those with CD4⁺ T-cell count ≥200 cells/mm³. GSH and WBC were found to be significantly (P < 0.05) increased in the female HIV-infected subjects when compared with the male counterpart. Anemia prevalence of 74 and 33% were recorded for the HIV-infected and control subjects, respectively. Gender and ART treatment were found to be associated with anemia in HIV. Male HIV-infected subjects on ART were found to be more likely to have anemia.

CONCLUSION

Antioxidants; GSH and GPX were found to be significantly reduced in HIV infection. Further probe showed that the antioxidant status was improved in the HIV-infected group on ART.

Drug hypersensitivity in HIV infection

PURPOSE OF REVIEW

Immune-mediated adverse drug reactions (IM-ADRs) are many times more common in HIV-infected patients. Usual offending drugs include antiretroviral and antiinfectives, but the burden of specific drug IM-ADRs is population-specific; changing as new and fixed dose combinations enter the market, and drug-resistance patterns demand. This review considers recent literature on epidemiology, mechanisms, clinical management and prevention of IM-ADRs amongst persons living with HIV/AIDS.

RECENT FINDINGS

Epidemiological studies continue to describe high rates of delayed hypersensitivity to known offenders, as well as similar reactions in preexposure prophylaxis. IM-ADRs to oral and injectable integrase strand transfer inhibitors are reported with expanding use. The clinical spectrum and management of IM-ADRs occurring in HIV-infected populations is similar to uninfected; with exceptions such as a recently described severe delayed efavirenz DILI with high mortality. Furthermore, the context can be unique, such as the lower than expected mortality in a Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) cohort from a HIV/TB high burden setting. Programmatic data showing the near complete elimination of Abacavir drug hypersensitivity syndrome following implementation of HLA-B57:01 screening is a stellar example of how prevention is possible with mechanistic insight.

SUMMARY

IM-ADRs remain a challenge in persons living with HIV. The complexities posed by polypharmacy, overlapping drug toxicities, drug interactions, overlap of IM-ADRs with other diseases, limited alternative drugs, and vulnerable patients with advanced immunosuppression with high mortality, necessitate increased use of drug provocation testing, treat-through and desensitization strategies. There is an urgent need for improved diagnostics and predictive biomarkers for prevention, or to guide treat-through, rechallenge and desensitization approaches.

Therapeutic Role of a Cysteine Precursor, OTC, in Ischemic Stroke Is Mediated by Improved Proteostasis in Mice

Oxidative stress aggravates brain injury following ischemia/reperfusion (I/R). We previously showed that ubiquilin-1 (Ubqln1), a ubiquitin-like protein, improves proteostasis and protects brains against oxidative stress and I/R-induced brain injury. Here, we demonstrate that a small molecule compound, L-2-oxothiazolidine-4-carboxylic acid (OTC) that functions as a precursor of cysteine, upregulated Ubqln1 and protected cells against oxygen-glucose deprivation-induced cell death in neuronal cultures. Further, the administration of OTC either at 1 h prior to ischemia or 3 h after the reperfusion significantly reduced brain infarct injury and improved behavioral outcomes in a stroke model. Administration of OTC also increased glutathione (GSH) level and decreased superoxide production, oxidized protein, and neuroinflammation levels in the penumbral cortex after I/R in the stroke mice. Furthermore, I/R reduced both Ubqln1 and the glutathione S-transferase protein levels, whereas OTC treatment restored both protein levels, which was associated with reduced ubiquitin-conjugated protein level. Interestingly, in the Ubqln1 knockout (KO) mice, OTC treatment showed reduced neuroprotection and increased ubiquitin-conjugated protein level when compared to the similarly treated non-KO mice following I/R, suggesting that OTC-medicated neuroprotection is, at least partially, Ubqln1-dependent. Thus, OTC is a potential therapeutic agent for stroke and possibly for other neurological disorders and its neuroprotection involves enhanced proteostasis.

Alteration of dietary cysteine affects activities of genes of the transsulfuration and glutathione pathways, and development of skin tissues and feather follicles in chickens

The dietary requirement for cysteine is not determined in poultry since it is not an essential amino acid. The cysteine need is expected to be met through the transsulfuration pathway where homocysteine, a precursor of methionine, is converted to cysteine. Cysteine is a major component of plumage, and the degree to which cysteine is involved in plumage and other keratized proteins are unknown. We randomly assigned chicks to control and treatment (deficient in cysteine) diets for 49 d. The thickness of the skin layers, feather follicle length, and thickness were measured at days 10, 24, 34, and 49. We also measured the hepatic mRNA expressions of cystathionine beta synthase (CBS), cystathionine γ-lyase (CTL), cysteine dioxygenase (CDO), and glutathione synthetase (GSS). Chickens fed the treatment diet had reduced epidermis thickness and shorter feather follicles compared with the controls. The chicken fed the treatment diet also had increased mRNA expression of CBS and CTL indicating a disruption of the transsulfuration pathway. The treatment chickens also had a decreased hepatic CDO and increased GSS mRNA expressions which are in concordance with the homeostatic regulation of cysteine. Compromised cysteine metabolism could affect thermoregulation and subsequently affect feed efficiency and welfare of the birds.

Biogreen Synthesis of Carbon Dots for Biotechnology and Nanomedicine Applications

Over the past decade, carbon dots have ignited a burst of interest in many different fields, including nanomedicine, solar energy, optoelectronics, energy storage, and sensing applications, owing to their excellent photoluminescence properties and the easiness to modify their optical properties through doping and functionalization. In this review, the synthesis, structural and optical properties, as well as photoluminescence mechanisms of carbon dots are first reviewed and summarized. Then, we describe a series of designs for carbon dot-based sensors and the different sensing mechanisms associated with them. Thereafter, we elaborate on recent research advances on carbon dot-based sensors for the selective and sensitive detection of a wide range of analytes, including heavy metals, cations, anions, biomolecules, biomarkers, nitroaromatic explosives, pollutants, vitamins, and drugs. Lastly, we provide a concluding perspective on the overall status, challenges, and future directions for the use of carbon dots in real-life sensing.

γ-glutamylcysteine exhibits anti-inflammatory effects by increasing cellular glutathione level

Sepsis is a life-threatening organ dysfunction caused by dysregulated host response to infection and characterized by redox imbalance and severe oxidative stress. Glutathione (GSH) serves several vital functions, including scavenging free radicals and maintaining intracellular redox balance. Extracellular GSH is unable to be taken into the majority of human cells, and the GSH prodrug N-acetyl-l-cysteine (NAC) does not exhibit promising clinical effects. γ-glutamylcysteine (γ-GC), an intermediate dipeptide of the GSH-synthesis pathway and harboring anti-inflammatory properties, represents a relatively unexplored option for sepsis treatment. The anti-inflammatory efficiency of γ-GC and the associated molecular mechanism need to be explored. In vivo investigation showed that γ-GC reduced sepsis lethality and attenuated systemic inflammatory responses in mice, as well as inhibited lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), high-mobility group box 1 (HMGB1), and nitric oxide (NO) and the expression of inducible NO synthase and cyclooxygenase 2 in RAW264.7 cells. Moreover, both in vivo and in vitro experiments demonstrated that γ-GC exhibited better therapeutic effects against inflammation compared with N-acetyl-L-cysteine (NAC) and GSH. Mechanistically, γ-GC suppressed LPS-induced reactive oxygen species accumulation and GSH depletion. Inflammatory stimuli, such as LPS treatment, upregulated the expression of glutathione synthetase via activating nuclear factor-erythroid 2-related factor (Nrf2) and nuclear factor kappa B (NF-κB) pathways, thereby promoting synthesis of GSH from γ-GC. These findings suggested that γ-GC might represent a potential therapeutic agent for sepsis treatment.

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γ-GC reduces sepsis lethality and attenuates inflammatory responses in BALB/c mice.

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γ-GC suppresses LPS-induced inflammation, ROS accumulation, and GSH depletion.

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Nrf2 and NF-κB pathways are essential for upregulating GSS level to promote GSH synthesis from γ-GC.

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γ-GC is more effective in attenuation inflammation than NAC and GSH.

Modulatory Effects of Nicotine on neuroHIV/neuroAIDS

Nicotine, one of the key active ingredients in tobacco smoke, exerts its effects via binding to nicotinic acetylcholine receptors (nAChRs). Although both negative and positive pharmacological effects of nicotine have been shown in numerous animals and human studies, its interaction with human immunodeficiency virus-1 (HIV-1) have not been fully elucidated. Even though combined anti-retroviral therapy (cART) limits the progression of HIV-1 to acquired immune deficiency syndrome (AIDS), HIV-associated neurocognitive disorders (HAND) remain prevalent. There is thus a compelling need to enhance our understanding of HAND-related neurologic dysfunction. Some biochemical pathways and physiological dysfunctions have been found to be shared by HAND and Alzheimer's (AD) or Parkinson's (PD) diseases, and nicotine may exert the same neuroprotection in HAND that has been observed in both AD and PD. In the past dozen years, various potential therapeutic effects of nicotine such as neuroprotection have been revealed in both in vivo and in vitro studies, including using HIV-1 transgenic (HIV-1Tg) rat model, which mimics HIV-infected patients receiving cART. In the current review, we describe recent progress in the prevalence of HIV/AIDS with and without cigarette smoking, some animal models for studying neural dysfunction associated with HIV-1 infection, elucidating the modulatory effects of cigarette smoking/nicotine on HIV/AIDS, the anti-inflammatory effects of nicotine, and the neuroprotective effects observed in HIV-1Tg rat model. Taken together, these findings suggest the following: although tobacco smoking does cause deleterious effects in both health and disease conditions such as HIV infection, nicotine, the significant component of tobacco smoke, has been shown to possess some neuroprotective effects in HIV patients, possible via its anti-inflammatory activities. It is therefore necessary to study nicotine's dual effects on neuroHIV/neuroAIDS in hope of better defining the potential medical uses of nicotine or its analogues, and to make them available in a purer and less dangerous form.

HIV-1 tat expression and sulphamethoxazole hydroxylamine mediated oxidative stress alter the disulfide proteome in Jurkat T cells

Background

Adverse drug reactions (ADRs) are a significant problem for HIV patients, with the risk of developing ADRs increasing as the infection progresses to AIDS. However, the pathophysiology underlying ADRs remains unknown. Sulphamethoxazole (SMX) via its active metabolite SMX-hydroxlyamine, when used prophylactically for pneumocystis pneumonia in HIV-positive individuals, is responsible for a high incidence of ADRs. We previously demonstrated that the HIV infection and, more specifically, that the HIV-1 Tat protein can exacerbate SMX-HA-mediated ADRs. In the current study, Jurkat T cell lines expressing Tat and its deletion mutants were used to determine the effect of Tat on the thiol proteome in the presence and absence of SMX-HA revealing drug-dependent changes in the disulfide proteome in HIV infected cells.

Protein lysates from HIV infected Jurkat T cells and Jurkat T cells stably transfected with HIV Tat and Tat deletion mutants were subjected to quantitative slot blot analysis, western blot analysis and redox 2 dimensional (2D) gel electrophoresis to analyze the effects of SMX-HA on the thiol proteome.

Results

Redox 2D gel electrophoresis demonstrated that untreated, Tat-expressing cells contain a number of proteins with oxidized thiols. The most prominent of these protein thiols was identified as peroxiredoxin. The untreated, Tat-expressing cell lines had lower levels of peroxiredoxin compared to the parental Jurkat E6.1 T cell line. Conversely, incubation with SMX-HA led to a 2- to 3-fold increase in thiol protein oxidation as well as a significant reduction in the level of peroxiredoxin in all the cell lines, particularly in the Tat-expressing cell lines.

Conclusion

SMX-HA is an oxidant capable of inducing the oxidation of reactive protein cysteine thiols, the majority of which formed intermolecular protein bonds. The HIV Tat-expressing cell lines showed greater levels of oxidative stress than the Jurkat E6.1 cell line when treated with SMX-HA. Therefore, the combination of HIV Tat and SMX-HA appears to alter the activity of cellular proteins required for redox homeostasis and thereby accentuate the cytopathic effects associated with HIV infection of T cells that sets the stage for the initiation of an ADR.

Electronic supplementary material

The online version of this article (10.1186/s12985-018-0991-x) contains supplementary material, which is available to authorized users.

Ferroptosis: bug or feature?

Ferroptosis is an iron-dependent, oxidative form of non-apoptotic cell death. This form of cell death does not share morphological, biochemical, or genetic similarities with classic necrosis, necroptosis, parthanatos, or other forms of non-apoptotic cell death. Ferroptosis can be triggered by depleting the cell of the amino acid cysteine, or by inhibiting the phospholipid hydroperoxidase glutathione peroxidase 4 (GPX4). Why certain stimuli trigger ferroptosis instead of another form of cell death, and whether this process could be adaptive in vivo, are two major unanswered questions concerning this process. Emerging evidence and consideration of related non-apoptotic pathways suggest that ferroptosis could be an adaptive process, albeit one regulated and executed in a manner very different from apoptosis and other forms of cell death.

Doxycycline-inducible and astrocyte-specific HIV-1 Tat transgenic mice (iTat) as an HIV/neuroAIDS model

HIV-1 Tat is known to be neurotoxic and important for HIV/neuroAIDS pathogenesis. However, the overwhelming majority of the studies involved use of recombinant Tat protein. To understand the contributions of Tat protein to HIV/neuroAIDS and the underlying molecular mechanisms of HIV-1 Tat neurotoxicity in the context of a whole organism and independently of HIV-1 infection, a doxycycline-inducible astrocyte-specific HIV-1 Tat transgenic mouse (iTat) was created. Tat expression in the brains of iTat mice was determined to be in the range of 1-5 ng/ml and led to astrocytosis, loss of neuronal dendrites, and neuroinflammation. iTat mice have allowed us to define the direct effects of Tat on astrocytes and the molecular mechanisms of Tat-induced GFAP expression/astrocytosis, astrocyte-mediated Tat neurotoxicity, Tat-impaired neurogenesis, Tat-induced loss of neuronal integrity, and exosome-associated Tat release and uptake. In this review, we will provide an overview about the creation and characterization of this model and its utilities for our understanding of Tat neurotoxicity and the underlying molecular mechanisms.

Childhood maltreatment and HIV-associated neurocognitive disorders share similar pathophysiology: a potential sensitisation mechanism?

HIV-associated neurocognitive disorders (HAND) are increasingly prevalent despite the use of antiretroviral therapies. Previous research suggests that individual host factors play an important role in determining susceptibility to HAND. In this review, we propose that childhood trauma (CT) and HAND share several common aetiological mechanisms, namely hypothalamic-pituitary-adrenal axis dysregulation, neuroinflammation and oxidative stress. These convergent and consequent mechanisms may translate into an increased risk of developing HAND in individuals who have experienced early life stress. We provide an overview of basic and clinical research relating to these pathophysiological mechanisms and suggest that further research examine brain-derived neurotrophic factor and telomere length as common mediating factors and potential therapeutic targets for HAND and CT. Graphical abstract Both childhood trauma and HIV-associated neurocognitive disorders are associated with HPA axis dysregulation, inflammation and oxidative stress.

Hepatic expression profiles in retroviral infection: relevance to drug hypersensitivity risk

HIV‐infected patients show a markedly increased risk of delayed hypersensitivity (HS) reactions to potentiated sulfonamide antibiotics (trimethoprim/sulfamethoxazole or TMP/SMX). Some studies have suggested altered SMX biotransformation in HIV infection, but hepatic biotransformation pathways have not been evaluated directly. Systemic lupus erythematosus (SLE) is another chronic inflammatory disease with a higher incidence of sulfonamide HS, but it is unclear whether retroviral infection and SLE share risk factors for drug HS. We hypothesized that retroviral infection would lead to dysregulation of hepatic pathways of SMX biotransformation, as well as pathway alterations in common with SLE that could contribute to drug HS risk. We characterized hepatic expression profiles and enzymatic activities in an SIV‐infected macaque model of retroviral infection, and found no evidence for dysregulation of sulfonamide drug biotransformation pathways. Specifically, NAT1,NAT2,CYP2C8,CYP2C9,CYB5R3,MARC1/2, and glutathione‐related genes (GCLC,GCLM,GSS,GSTM1, and GSTP1) were not differentially expressed in drug naïve SIVmac239‐infected male macaques compared to age‐matched controls, and activities for SMX N‐acetylation and SMX hydroxylamine reduction were not different. However, multiple genes that are reportedly over‐expressed in SLE patients were also up‐regulated in retroviral infection, to include enhanced immunoproteasomal processing and presentation of antigens as well as up‐regulation of gene clusters that may be permissive to autoimmunity. These findings support the hypothesis that pathways downstream from drug biotransformation may be primarily important in drug HS risk in HIV infection.

Glutathione - From antioxidant to post-translational modifier

Helmut Sies is one of the leading investigators in the multiple roles of glutathione (GSH) in biology. He has pioneered work on the role of GSH in preventing oxidative stress, in transport of GSSG, in protection of protein thiols from irreversible oxidation through mixed disulfide formation and demonstrated a role of protein glutathionylation in response to hormonal stimulation well before redox signaling became a major subject of investigation. Here I will describe the roles of GSH in several aspects of biology, the work of my laboratory in those findings, and how Helmut Sies work influenced our studies.

Analysis of glutathione levels in the brain tissue samples from HIV-1-positive individuals and subject with Alzheimer's disease and its implication in the pathophysiology of the disease process

HIV-1 positive individuals are at high risk for susceptibility to both pulmonary tuberculosis (TB) and extra-pulmonary TB, including TB meningitis (TBM) which is an extreme form of TB. The goals of this study are to determine the mechanisms responsible for compromised levels of glutathione (GSH) in the brain tissue samples derived from HIV-1-infected individuals and individuals with Alzheimer's disease (AD), investigate the possible underlying mechanisms responsible for GSH deficiency in these pathological conditions, and establish a link between GSH levels and pathophysiology of the disease processes. We demonstrated in the autopsied human brain tissues that the levels of total and reduced forms of GSH were significantly compromised in HIV-1 infected individuals compared to in healthy subjects and individuals with AD. Brain tissue samples derived from HIV-1-positive individuals had substantially higher levels of free radicals than that derived from healthy and AD individuals. Enzymes that are responsible for the de novo synthesis of GSH such as γ-glutamate cysteine-ligase catalytic subunit (GCLC-rate limiting step enzyme) and glutathione synthetase (GSS-enzyme involved in the second step reaction) were significantly decreased in the brain tissue samples derived from HIV-1-positive individuals with low CD4 + T-cells (< 200 cells/mm³) compared to healthy and AD individuals. Levels of glutathione reductase (GSR) were also decreased in the brain tissue samples derived from HIV-1 infected individuals. Overall, our findings demonstrate causes for GSH deficiency in the brain tissue from HIV-1 infected individuals explaining the possible reasons for increased susceptibility to the most severe form of extra-pulmonary TB, TBM.

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Total and reduced forms of GSH were significantly compromised in the brain tissues derived from HIV-1 infected individuals.

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Brain tissue samples derived from HIV-1-positive individuals had substantially higher levels of free radicals.

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GSH de novo synthesis enzymes were significantly decreased in HIV-1-positive individuals with low CD4 + T-cells.

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Levels of GSR were also decreased in the brain tissue samples derived from HIV-1 infected individuals.

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Overall, our findings demonstrate causes for GSH deficiency in the brain tissue from HIV-1 infected individuals.

Astrocyte elevated gene-1 (AEG-1) and the A(E)Ging HIV/AIDS-HAND

Recent attempts to analyze human immunodeficiency virus (HIV)-1-induced gene expression changes in astrocytes uncovered a multifunctional oncogene, astrocyte elevated gene-1 (AEG-1). Our previous studies revealed that AEG-1 regulates reactive astrocytes proliferation, migration and inflammation, hallmarks of aging and CNS injury. Moreover, the involvement of AEG-1 in neurodegenerative disorders, such as Huntington's disease and migraine, and its induction in the aged brain suggest a plausible role in regulating overall CNS homeostasis and aging. Therefore, it is important to investigate AEG-1 specifically in aging-associated cognitive decline. In this study, we decipher the common mechanistic links in cancer, aging and HIV-1-associated neurocognitive disorders that likely contribute to AEG-1-based regulation of astrocyte responses and function. Despite AEG-1 incorporation into HIV-1 virions and its induction by HIV-1, tumor necrosis factor-α and interleukin-1β, the specific role(s) of AEG-1 in astrocyte-driven HIV-1 neuropathogenesis are incompletely defined. We propose that AEG-1 plays a central role in a multitude of cellular stress responses involving mitochondria, endoplasmic reticulum and the nucleolus. It is thus important to further investigate AEG-1-based cellular and molecular regulation in order to successfully develop better therapeutic approaches that target AEG-1 to combat cancer, HIV-1 and aging.

An Adverse Drug Reaction to Trimethoprim-Sulfamethoxazole Revealing Primary HIV: A Case Report and Literature Review

Adverse drug reactions (ADRs) to antibiotics complicate the management of any infection, particularly opportunistic infections in advanced HIV as some ADRs are potentiated by HIV. Trimethoprim-sulfamethoxazole (TMP-SMX) causes ADRs in 40-80% of HIV infected individuals, compared to 3-5% in the general population. The incidence and severity of ADRs among HIV infected individuals appear to increase as they progress from latent infection to AIDS. We present a single case report of a 55-year-old African American male found to have an otherwise asymptomatic acute HIV infection who developed an ADR to TMP-SMX, despite having previously tolerating the medication. The proposed mechanisms for the increased incidence of sulfa hypersensitivity reactions among HIV infected individuals focus on either (1) HIV-induced changes in the immune function driven by falling levels of CD4 cells or (2) other HIV-specific factors correlated with rising viral load. To our knowledge this is the first reported case of new sulfa hypersensitivity in primary HIV and may provide clinical evidence to support the correlation between viral load and ADRs to TMP-SMX without a severely diminished CD4 count, though further research is necessary. This case also demonstrates a rare and easily overlooked presentation of HIV that may aid in early diagnosis.

The cross-talk of HIV-1 Tat and methamphetamine in HIV-associated neurocognitive disorders

Antiretroviral therapy has dramatically improved the lives of human immunodeficiency virus 1 (HIV-1) infected individuals. Nonetheless, HIV-associated neurocognitive disorders (HAND), which range from undetectable neurocognitive impairments to severe dementia, still affect approximately 50% of the infected population, hampering their quality of life. The persistence of HAND is promoted by several factors, including longer life expectancies, the residual levels of virus in the central nervous system (CNS) and the continued presence of HIV-1 regulatory proteins such as the transactivator of transcription (Tat) in the brain. Tat is a secreted viral protein that crosses the blood–brain barrier into the CNS, where it has the ability to directly act on neurons and non-neuronal cells alike. These actions result in the release of soluble factors involved in inflammation, oxidative stress and excitotoxicity, ultimately resulting in neuronal damage. The percentage of methamphetamine (MA) abusers is high among the HIV-1-positive population compared to the general population. On the other hand, MA abuse is correlated with increased viral replication, enhanced Tat-mediated neurotoxicity and neurocognitive impairments. Although several strategies have been investigated to reduce HAND and MA use, no clinically approved treatment is currently available. Here, we review the latest findings of the effects of Tat and MA in HAND and discuss a few promising potential therapeutic developments.

The role of cellular oxidoreductases in viral entry and virus infection-associated oxidative stress: potential therapeutic applications

INTRODUCTION

Cellular oxidoreductases catalyze thiol/disulfide exchange reactions in susceptible proteins and contribute to the cellular defense against oxidative stress. Oxidoreductases and oxidative stress are also involved in viral infections. In this overview, different aspects of the role of cellular oxidoreductases and oxidative stress during viral infections are discussed from a chemotherapeutic viewpoint.

AREAS COVERED

Entry of enveloped viruses into their target cells is triggered by the interaction of viral envelope glycoproteins with cellular (co)receptor(s) and depends on obligatory conformational changes in these viral envelope glycoproteins and/or cellular receptors. For some viruses, these conformational changes are mediated by cell surface-associated cellular oxidoreductases, which mediate disulfide bridge reductions in viral envelope glycoprotein(s). Therefore, targeting these oxidoreductases using oxidoreductase inhibitors might yield an interesting strategy to block viral entry of these viruses. Furthermore, since viral infections are often associated with systemic oxidative stress, contributing to disease progression, the enhancement of the cellular antioxidant defense systems might have potential as an adjuvant antiviral strategy, slowing down disease progression.

EXPERT OPINION

Promising antiviral data were obtained for both strategies. However, potential pitfalls have also been identified for these strategies, indicating that it is important to carefully assess the benefits versus risks of these antiviral strategies.

Arsenic responsive microRNAs in vivo and their potential involvement in arsenic-induced oxidative stress

Arsenic exposure is postulated to modify microRNA (miRNA) expression, leading to changes of gene expression and toxicities, but studies relating the responses of miRNAs to arsenic exposure are lacking, especially with respect to in vivo studies. We utilized high-throughput sequencing technology and generated miRNA expression profiles of liver tissues from Sprague Dawley (SD) rats exposed to various concentrations of sodium arsenite (0, 0.1, 1, 10 and 100mg/L) for 60days. Unsupervised hierarchical clustering analysis of the miRNA expression profiles clustered the SD rats into different groups based on the arsenic exposure status, indicating a highly significant association between arsenic exposure and cluster membership (p-value of 0.0012). Multiple miRNA expressions were altered by arsenic in an exposure concentration-dependent manner. Among the identified arsenic-responsive miRNAs, several are predicted to target Nfe2l2-regulated antioxidant genes, including glutamate-cysteine ligase (GCL) catalytic subunit (GCLC) and modifier subunit (GCLM) which are involved in glutathione (GSH) synthesis. Exposure to low concentrations of arsenic increased mRNA expression for Gclc and Gclm, while high concentrations significantly reduced their expression, which were correlated to changes in hepatic GCL activity and GSH level. Moreover, our data suggested that other mechanisms, e.g., miRNAs, rather than Nfe2l2-signaling pathway, could be involved in the regulation of mRNA expression of Gclc and Gclm post-arsenic exposure in vivo. Together, our findings show that arsenic exposure disrupts the genome-wide expression of miRNAs in vivo, which could lead to the biological consequence, such as an altered balance of antioxidant defense and oxidative stress.

Independent and co-morbid HIV infection and Meth use disorders on oxidative stress markers in the cerebrospinal fluid and depressive symptoms

Both HIV infection and Methamphetamine (Meth) use disorders are associated with greater depressive symptoms and oxidative stress; whether the two conditions would show additive or interactive effects on the severity of depressive symptoms, and whether this is related to the level of oxidative stress in the CNS is unknown. 123 participants were evaluated, which included 41 HIV-seronegative subjects without substance use disorders (Control), 25 with recent (<6 months) moderate to severe Meth use disorders (Meth), 34 HIV-seropositive subjects without substance use disorders (HIV) and 23 HIV+Meth subjects. Depressive symptoms were assessed with the Center for Epidemiologic Studies-Depression Scale (CES-D), and oxidative stress markers were evaluated with glutathione (GSH), 4-hydroxynonenal (HNE), and activities of gamma-glutamyltransferase (GGT) and glutathione peroxidase (GPx) in the cerebrospinal fluid (CSF). Compared with Controls, HIV subjects had higher levels of HNE (+350%) and GGT (+27%), and lower level of GSH (-34%), while Meth users had higher levels of GPx activity (+23%) and GSH (+30 %). GGT correlated with GPx, and with age, across all subjects (p < 0.0001). CES-D scores correlated with CSF HNE levels only in Control and HIV groups, but not in Meth and HIV+Meth groups. HIV and Meth use had an interactive effects on depressive symptoms, but did not show additive or interactive effects on oxidative stress. The differential relationship between depressive symptoms and oxidative stress response amongst the four groups suggest that depressive symptoms in these groups are mediated through different mechanisms which are not always related to oxidative stress.

Nutritional supplementation with the mushroom Agaricus sylvaticus reduces oxidative stress in children with HIV

BACKGROUND

The involvement of free radicals and oxidative stress in HIV infection has been extensively studied, and the benefits of antioxidant supplementation in animal studies have been demonstrated. However, few studies have demonstrated a benefit in clinical studies.

OBJECTIVE

To verify the effects of dietary supplementation with Agaricus sylvaticus, a mushroom rich in antioxidants, on the oxidative profile of children born with HIV undergoing antiretroviral therapy.

DESIGN

The sample included 24 children (both boys and girls) between two and eight years of age, of whom 10 were HIV positive and received supplementation with Agaricus sylvaticus for a three-month period, and 14 were HIV negative and received no supplementation. At the beginning and conclusion of the study, thiobarbituric acid-reactive substances (TBARS), nitrite and nitrate (NN), Trolox equivalent antioxidant capacity, and the antioxidant capacity of inhibition of diphenyl-picrilhidrazil (DPPH) free radicals were analyzed.

RESULTS

Before supplementation, significantly higher values of TBARS and NN, but decreased values of DPPH, were observed in infected subjects when compared with HIV-negative subjects. After supplementation, a reduction of TBARS and NN values and an increase in DPPH and Trolox equivalent antioxidant capacity values were observed in HIV-positive subjects.

CONCLUSIONS

The results of the present study suggest the involvement of oxidative stress in HIV infection, with the participation of NN synthesis. Additionally, supplementation reversed oxidative alterations and improved antioxidant defense in infected individuals, and may become a complementary strategy in the treatment of these patients.

Evaluating Liver Fibrosis by Transient Elastometry in Patients With HIV-HCV Coinfection and Monoinfection

BACKGROUND

Due to the high efficacy of combination antiretroviral therapy (cART), the number of patients living with HIV is increasing. Chronic HCV infection has become a leading cause of non-AIDS related morbidity and mortality in patients with HIV infection.

OBJECTIVES

The aim of this cross-sectional study was to identify factors associated with liver fibrosis (LF) in patients with HIV monoinfection and HIV-HCV coinfection.

PATIENTS AND METHODS

We analyzed LF by transient elastometry ([TE], Fibroscan) in three groups of patients (HIV, HIV-HCV and HCV) followed at the Infectious Diseases Department of University of Ancona, Italy, between October 2009 and November 2012.

RESULTS

In total, 354 adults including 98 HIV, 70 HIV-HCV and 186 HCV patients were studied. HIV-HCV patients had a longer duration of HIV (P < 0.006) and HCV (P < 0.001) infections. Additionally, they were receiving cART therapy for a longer period (P < 0.001); they had higher prevalence of lipodystrophy (P < 0.001) and higher HCV load (P = 0.004). LF was significantly more pronounced in HCV and HIV-HCV compared to HIV patients (P < 0.001). A total of 13.3%, 39.2% and 51.4% of HIV, HCV and HIV-HCV, respectively, showed a LF ≥ F2. Additionally, a severe LF (F = 4) was significantly more frequent among HIV-HCV compared to other groups. A longer exposure to didanosine, stavudine, lopinavir/ritonavir and fosamprenavir resulted in increased LF by univariate analysis (P ranging from < 0.001 to 0.007). By logistic regression analysis, the only variables significantly associated with increased LF were HCV coinfection, older age, and high AST values (P ranging from < 0.001 to 0.036).

CONCLUSIONS

HCV coinfection, older age and AST were associated with LF in patients with HIV infection.

Glutathione synthesis is compromised in erythrocytes from individuals with HIV

We demonstrated that the levels of enzymes responsible for the synthesis of glutathione (GSH) such as glutathione synthase (GSS), glutamate-cysteine ligase-catalytic subunit (GCLC), and glutathione reductase (GSR) were significantly reduced in the red blood cells (RBCs) isolated from individuals with human immunodeficiency virus (HIV) infection and this reduction correlated with decreased levels of intracellular GSH. GSH content in RBCs can be used as a marker for increased overall oxidative stress and immune dysfunctions caused by HIV infection. Our data supports our hypothesis that compromised levels of GSH in HIV infected individuals’ is due to decreased levels of GSH-synthetic enzymes. The role of GSH in combating oxidative stress and improving the functions of immune cells in HIV patients’ indicates the benefit of an antioxidant supplement which can reduce the cellular damage and promote the functions of immune cells.

Immunoneuropathogenesis of HIV-1 clades B and C: role of redox expression and thiol modification

Previous studies have shown that, during infection, HIV-1 clade B and clade C differentially contribute to the neuropathogenesis and development of HIV-associated neurocognitive disorders (HANDs). The low-molecular-weight tripeptide glutathione (GSH) alters the redox balance and leads to the generation of reactive oxygen species, which play a significant role in the neuropathogenesis of HANDs. We hypothesized that the HIV-1 clade B and clade C viruses and their respective Tat proteins exert differential effects on monocyte-derived immature dendritic cells (IDCs) and neuroblastoma cells (SK-N-MC) by redox activation, which leads to immunoneuropathogenesis. The GSH/GSSG ratio and mRNA expression levels and protein modification of glutathione synthetase (GSS), glutathione peroxidase 1 (GPx1), superoxide dismutase 1 (SOD1), and catalase (CAT) were analyzed in IDCs infected with HIV-1 clade B or clade C as well as in cells treated with the respective Tat proteins. The results indicated that HIV-1 clade B virus and its Tat protein significantly increased the production of reactive oxygen species and reduced the GSH/GSSG ratio and subsequent downregulation of gene expression and protein modification of GSS, GPx1, SOD1, and CAT compared to infection with the clade C virus or treatment with the clade C Tat protein. Thus, our studies demonstrate that HIV-1 clades B and C exert differential effects of redox expression and thiol modification. HIV-1 clade B potentially induces oxidative stress, leading to more immunoneuropathogenesis than infection with HIV-1 clade C.

Roles of glutathione in antioxidant defense, inflammation, and neuron differentiation in the thalamus of HIV-1 transgenic rats

Inflammation and oxidative stress in the brain are major causes of HIV-associated neurocognitive disorders. Previously we have reported high content of glutathione (GSH) in the thalamus of rats with F344 genetic background. In this study, we investigated the changes of GSH metabolism and GSH-dependent antioxidant enzymes in the rat thalamus in response to HIV-1 transgenesis, and their associations with oxidative stress, inflammation, and neuronal development. Male HIV-1 transgenic (HIV-1Tg) rats and wild type F344 rats at 10 months were used in this study, with 5 rats in each group. Parameters measured in this study included: total and oxidized GSH, glutathione peroxidase (GPx), glutathione-S-transferase (GST), gamma-glutamylcysteine synthetase (GCS), gamma-glutamyl transferase (GGT), cysteine/cystine transporters, 4-hydroxynonenal (HNE), interleukin 12 (IL12), neuronal nuclei (NeuN), microtubule-associated protein (MAP2), and glia fibrillary acidic protein (GFAP). The levels of total GSH, oxidized GSH (GSSG) and MAP2 protein, and enzymatic activities of GCS, GPx and GST were significantly higher in HIV-1Tg rats compared with F344 rats, but the ratio of GSSG/GSH, activity of GGT and levels of HNE, NeuN protein and GFAP protein did not change. HIV-1Tg rats showed a lower level of IL12 protein. GSH positively correlated with GCS, GST and MAP2, GSSG/GSH ratio positively correlated with HNE and IL12, the activities of GPx, GST and GCS positively correlated with each other, and negatively correlated with HNE. These findings suggest an important role of the GSH-centered system in reducing oxidative stress and neuroinflammation, and enhancing neuron differentiation in the thalamus of HIV-1Tg rats.

Aging and HIV/AIDS: pathogenetic role of therapeutic side effects

The intersection of aging and HIV/AIDS is a looming 'epidemic within an epidemic.' This paper reviews how HIV/AIDS and its therapy cause premature aging or contribute mechanistically to HIV-associated non-AIDS illnesses (HANA). Survival with HIV/AIDS has markedly improved by therapy combinations containing nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors, and protease inhibitors (PIs) called HAART (highly active antiretroviral therapy). Because NRTIs and PIs together prevent or attenuate HIV-1 replication, and prolong life, the population of aging patients with HIV/AIDS increases accordingly. However, illnesses frequently associated with aging in the absence of HIV/AIDS appear to occur prematurely in HIV/AIDS patients. Theories that help to explain biological aging include oxidative stress (where mitochondrial oxidative injury exceeds antioxidant defense), chromosome telomere shortening with associated cellular senescence, and accumulation of lamin A precursors (a nuclear envelop protein). Each of these has the potential to be enhanced or caused by HIV/AIDS, antiretroviral therapy, or both. Antiretroviral therapy has been shown to enhance events seen in biological aging. Specifically, antiretroviral NRTIs cause mitochondrial dysfunction, oxidative stress, and mitochondrial DNA defects that resemble features of both HANA and aging. More recent clinical evidence points to telomere shortening caused by NRTI triphosphate-induced inhibition of telomerase, suggesting telomerase reverse transcriptase (TERT) inhibition as being a pathogenetic contributor to premature aging in HIV/AIDS. PIs may also have a role in premature aging in HIV/AIDS as they cause prelamin A accumulation. Overall, toxic side effects of HAART may both resemble and promote events of aging and are worthy of mechanistic studies.

Identification of nitrated immunoglobulin variable regions in the HIV-infected human brain: implications in HIV infection and immune response

HIV can infiltrate the brain and lead to HIV-associated neurocognitive disorders (HAND). The pathophysiology of HAND is poorly understood, and there are no diagnostic biomarkers for it. Previously, an increase in inducible nitric oxide synthase levels and protein tyrosine nitration in the brain were found to correlate with the severity of HAND.1,2 In this study, we analyzed human brains from individuals who had HIV infection without encephalitis and with encephalitis/HAND and compared them to the brains of healthy individuals. We identified the nitrated proteins and determined the sites of modification using affinity enrichment followed by high-resolution and high-mass-accuracy nanoLC–MS/MS. We found that nitrated proteins were predominantly present in the HIV-infected individuals with encephalitis, and, interestingly, the modifications were predominantly located on immunoglobulin variable regions. Our molecular model indicated potential interactions with HIV envelope proteins and changes on the heavy and light chain interface upon the nitration and nitrohydroxylation of these residues. Therefore, our findings suggest a role for these modifications in the immune response, which may have implications in disease pathogenesis.

Transcriptional regulation of glutathione biosynthesis genes, γ-glutamyl-cysteine ligase and glutathione synthetase in response to cadmium and nonylphenol in Chironomus riparius

We characterized Chironomus riparius glutathione (GSH) biosynthesis genes, γ-glutamyl-cysteine ligase catalytic subunit (cr-gcl) and glutathione synthetase (cr-gs) and studied their expression after cadmium (Cd) and nonylphenol (NP) exposure. The full length cDNA of the Cr-GCL catalytic subunit was 2185 base pair (bp) in length containing an open reading frame of 1905bp, a 13bp 5' and 267bp 3' untranslated regions. The theoretical molecular mass of the deduced amino acid sequence (633) was 72.65kDa with an estimated pI of 5.42. The partial cDNA of Cr-GS was 739bp in length consisting 221 amino acids. The deduced amino acid sequence of Cr-GCL and Cr-GS cDNAs showed high conservation with homologs from other species. In phylogenetic analysis Cr-GCL and Cr-GS were grouped with equivalent genes from insects belonging to the dipteran order. The expression of cr-gcl and cr-gs was measured using quantitative real-time PCR after exposure to sub lethal concentrations of Cd (2, 10 and 20mg/L) and NP (10, 50 and 100μg/L) for 12, 24, 48 and 72h using real-time PCR methods. The mRNA expression of Cr-GCL and Cr-GS was significantly modulated after exposure to different concentrations of Cd and NP for different time periods. Total GSH levels showed a non-significant decrease after exposure to Cd for 24h. However, no change in GSH levels was observed after exposure to NP for 24h. These results suggest that Cr-GS and Cr-GCL expression is modulated by Cd and NP stress and may play an important role in detoxification of xenobiotics and antioxidant defense. We conclude that Cr-GS and Cr-GCL could be used as biomarkers of Cd and NP stress in aquatic environment for the studied species.

Oxidative stress and the HIV-infected brain proteome

Human immunodeficiency virus (HIV) is capable of infiltrating the brain and infecting brain cells. In the years following HIV infection, patients show signs of various levels of neurocognitive problems termed HIV-associated neurocognitive disorders (HAND). Although the introduction of highly active antiretroviral therapy (HAART) has reduced the incidence of HIV-dementia, which is the most severe form of HAND, the milder forms have become more prevalent today due to the increased life expectancy of infected individuals. Pre-HAART era markers such as HIV RNA level, CD4+ count, TNF-α, MCP-1 and M-CSF are not able to clearly distinguish mild from advanced HAND. One promising approach for new biomarker discovery is the identification and quantitation of proteins that are post-translationally modified by oxidative and nitrosative species. The occurrence of oxidative and nitrosative stress in HIV-infected brain, both through the early direct and indirect effects of viral proteins and through the later effect on mitochondrial integrity during apoptosis, is well-established. This review will focus on how the reactive species are produced in the brain after HIV infection, the specific oxidative and nitrosative species that are involved in the post-translational modification of the brain proteome, and the methods that are currently used for the detection of such modified proteins. This review also provides an overview of related research pertaining to oxidative stress-related HAND using cerebrospinal fluid and human brain tissue.

Didanosine (ddI) associates with increased liver fibrosis in adult HIV-HCV coinfected patients

The role of exposure to antiretrovirals (ARV) and serum matrix metalloproteases (MMPs) on liver fibrosis (LF) progression in human immunodeficiency virus (HIV) mono or HIV- hepatitis C virus (HCV) coinfection is unclear. Thus, 213 Caucasian adult HIV-infected patients were studied, 111 of whom had HCV-coinfection and 68 were HCV-monoinfected. Patients with ethanol consumption >50 g/day, hepatitis B coinfection, non-infective liver diseases or HAART adherence <75% were excluded. LF was assessed by transient elastometry (TE, Fibroscan). Serum levels of MMPs (MMP -1,-2,-3,-8,-9,-10 and -13) and their tissue inhibitors (TIMP-1,-2 and -4) were measured by ELISA microarrays. Associations with LF were statistically analysed. Protease inhibitors, usually administered to patients with advanced LF were excluded from the analysis. Increased LF was significantly associated with d4T (P = 0.006) and didanosine (ddI) use (P = 0.007), months on d4T (P = 0.001) and on ARV (P = 0.025), duration of HIV (P < 0.0001) and HCV infections (P < 0.0001), higher HIV (P = 0.03) and HCV loads (P < 0.0001), presence of lipodystrophy (P = 0.02), male gender (P = 0.02), older age (P = 0.04), low nadir (P = 0.02) and current CD4(+) T-cells (P < 0.0001), low gain of CD4(+) T-cells after HAART (P = 0.01) and higher MMP-2 (P = 0.02) and TIMP-2 serum levels (P = 0.02). By logistic regression the only variables significantly associated with increased LF were: use of ddI (OR 8.77, 95% CI: 2.36-32.26; P = 0.005), male gender (OR 7.75, 95% CI: 2.33-25.64, P = 0.0008), HCV viral load (in log) (OR 3.53, 95% CI: 2.16-5.77; P < 0.0001) and age (in years) (OR 1.21, 95% CI: 1.09-1.34, P = 0.0003). We conclude that only higher HCV viral load, older age, male gender, and use of ddI associated independently with increased LF in our study.

Glutathione synthesis

BACKGROUND

Glutathione (GSH) is present in all mammalian tissues as the most abundant non-protein thiol that defends against oxidative stress. GSH is also a key determinant of redox signaling, vital in detoxification of xenobiotics, and regulates cell proliferation, apoptosis, immune function, and fibrogenesis. Biosynthesis of GSH occurs in the cytosol in a tightly regulated manner. Key determinants of GSH synthesis are the availability of the sulfur amino acid precursor, cysteine, and the activity of the rate-limiting enzyme, glutamate cysteine ligase (GCL), which is composed of a catalytic (GCLC) and a modifier (GCLM) subunit. The second enzyme of GSH synthesis is GSH synthetase (GS).

SCOPE OF REVIEW

This review summarizes key functions of GSH and focuses on factors that regulate the biosynthesis of GSH, including pathological conditions where GSH synthesis is dysregulated.

MAJOR CONCLUSIONS

GCL subunits and GS are regulated at multiple levels and often in a coordinated manner. Key transcription factors that regulate the expression of these genes include NF-E2 related factor 2 (Nrf2) via the antioxidant response element (ARE), AP-1, and nuclear factor kappa B (NFκB). There is increasing evidence that dysregulation of GSH synthesis contributes to the pathogenesis of many pathological conditions. These include diabetes mellitus, pulmonary and liver fibrosis, alcoholic liver disease, cholestatic liver injury, endotoxemia and drug-resistant tumor cells.

GENERAL SIGNIFICANCE

GSH is a key antioxidant that also modulates diverse cellular processes. A better understanding of how its synthesis is regulated and dysregulated in disease states may lead to improvement in the treatment of these disorders. This article is part of a Special Issue entitled Cellular functions of glutathione.

Transforming growth factor β suppresses glutamate-cysteine ligase gene expression and induces oxidative stress in a lung fibrosis model

The concentration of glutathione (GSH), the most abundant intracellular free thiol and an important antioxidant, is decreased in the lung in both fibrotic diseases and experimental fibrosis models. The underlying mechanisms and biological significance of GSH depletion, however, remain unclear. Transforming growth factor β (TGF-β) is the most potent and ubiquitous profibrogenic cytokine and its expression is increased in almost all fibrotic diseases. In this study, we show that increasing TGF-β1 expression in mouse lung to a level comparable to those found in lung fibrotic diseases by intranasal instillation of AdTGF-β1(223/225), an adenovirus expressing constitutively active TGF-β1, suppressed the expression of both catalytic and modifier subunits of glutamate-cysteine ligase (GCL), the rate-limiting enzyme in de novo GSH synthesis, decreased GSH concentration, and increased protein and lipid peroxidation in mouse lung. Furthermore, we show that increasing TGF-β1 expression activated JNK and induced activating transcription factor 3, a transcriptional repressor involved in the regulation of the catalytic subunit of GCL, in mouse lung. Control virus (AdDL70-3) had no significant effect on any of these parameters, compared to saline-treated control. Concurrent with GSH depletion, TGF-β1 induced lung epithelial apoptosis and robust pulmonary fibrosis. Importantly, lung GSH levels returned to normal, whereas fibrosis persisted at least 21 days after TGF-β1 instillation. Together, the data suggest that increased TGF-β1 expression may contribute to the GSH depletion observed in pulmonary fibrosis diseases and that GSH depletion may be an early event in, rather than a consequence of, fibrosis development.

Polymorphism in glutamate cysteine ligase catalytic subunit (GCLC) is associated with sulfamethoxazole-induced hypersensitivity in HIV/AIDS patients

Background

Sulfamethoxazole (SMX) is a commonly used antibiotic for prevention of infectious diseases associated with HIV/AIDS and immune-compromised states. SMX-induced hypersensitivity is an idiosyncratic cutaneous drug reaction with genetic components. Here, we tested association of candidate genes involved in SMX bioactivation and antioxidant defense with SMX-induced hypersensitivity.

Results

Seventy seven single nucleotide polymorphisms (SNPs) from 14 candidate genes were genotyped and assessed for association with SMX-induced hypersensitivity, in a cohort of 171 HIV/AIDS patients. SNP rs761142 T > G, in glutamate cysteine ligase catalytic subunit (GCLC), was significantly associated with SMX-induced hypersensitivity, with an adjusted p value of 0.045. This result was replicated in a second cohort of 249 patients (p = 0.025). In the combined cohort, heterozygous and homozygous carriers of the minor G allele were at increased risk of developing hypersensitivity (GT vs TT, odds ratio = 2.2, 95% CL 1.4-3.7, p = 0.0014; GG vs TT, odds ratio = 3.3, 95% CL 1.6 – 6.8, p = 0.0010). Each minor allele copy increased risk of developing hypersensitivity 1.9 fold (95% CL 1.4 – 2.6, p = 0.00012). Moreover, in 91 human livers and 84 B-lymphocytes samples, SNP rs761142 homozygous G allele carriers expressed significantly less GCLC mRNA than homozygous TT carriers (p < 0.05).

Conclusions

rs761142 in GCLC was found to be associated with reduced GCLC mRNA expression and with SMX-induced hypersensitivity in HIV/AIDS patients. Catalyzing a critical step in glutathione biosynthesis, GCLC may play a broad role in idiosyncratic drug reactions.

HIV-1, reactive oxygen species, and vascular complications

Over 1 million people in the United States and 33 million individuals worldwide suffer from HIV/AIDS. Since its discovery, HIV/AIDS has been associated with an increased susceptibility to opportunistic infection due to immune dysfunction. Highly active antiretroviral therapies restore immune function and, as a result, people infected with HIV-1 are living longer. This improved survival of HIV-1 patients has revealed a previously unrecognized risk of developing vascular complications, such as atherosclerosis and pulmonary hypertension. The mechanisms underlying these HIV-associated vascular disorders are poorly understood. However, HIV-induced elevations in reactive oxygen species (ROS), including superoxide and hydrogen peroxide, may contribute to vascular disease development and progression by altering cell function and redox-sensitive signaling pathways. In this review, we summarize the clinical and experimental evidence demonstrating HIV- and HIV antiretroviral therapy-induced alterations in reactive oxygen species and how these effects are likely to contribute to vascular dysfunction and disease.

Lipid peroxides and glutathione status in human progenitor mononuclear (U937) cells following exposure to low doses of nickel and copper

Effects of Cu(2+), Ni(2+) or Cu(2+) + Ni(2+) on lipid peroxide and glutathione (GSH) levels in U937 cells were investigated. Cells were treated with 0, 5, 10, and 20 µM of Cu(2+) and/or Ni(2+) and H(2)O(2) (0.01 mM) and incubated for 24 hours at 37°C. Lipid peroxides were measured by the thiobarbituric acid assay (TBA). GSH intracellular levels were assayed by the GSH assay kit from EMD/Calbiochem (San Diego, California, USA). Cu(2+) or Ni(2+) significantly (P < 0.01) increased lipid peroxides in a dose-dependent manner, compared to controls. The effect was more pronounced for Cu(2+), compared to the Ni(2+)-treated samples. Cu(2+) + Ni(2+) increased lipid peroxides in a significant (P < 0.001), dose-dependent manner, compared to Cu(2+) or Ni(2+) alone (i.e., ratio of 2.5:1-fold for combined versus single treatments, respectively). Cu(2+) or Ni(2+) significantly decreased GSH levels in U937 cells, with the effect being pronounced for Cu(2+). Cu(2+) + Ni(2+) metal ions significantly (P < 0.001) depleted cells of GSH in a dose-dependent manner. Ethylene diamine tetraacetic acid (EDTA) at 50 or 100 µM moderately reduced the Cu(2+)- or Ni(2+)-induced effects on GSH levels. Interestingly, GSH levels generally decreased to half (except for the combined metal dose of 20 µM at 100 µM EDTA) of its level at the highest metal concentration tested for both the single or combined treatments. In conclusion, multiple exposures of cells to metal ions may be lethal to cells, compared to their single treatments.