N-acetylcysteine: a new approach to anti-HIV therapy

Experimental pharmacological approaches to reverse impaired awareness of hypoglycemia-a review

The colossal global burden of diabetes management is compounded by the serious complication of hypoglycemia. Protective physiologic hormonal and neurogenic counterregulatory responses to hypoglycemia are essential to preserve glucose homeostasis and avert serious morbidity. With recurrent exposure to hypoglycemic episodes over time, these counterregulatory responses to hypoglycemia can diminish, resulting in an impaired awareness of hypoglycemia (IAH). IAH is characterized by sudden neuroglycopenia rather than preceding cautionary autonomic symptoms. IAH increases the risk of subsequent sudden and severe hypoglycemic episodes in patients with diabetes. The postulated causative mechanisms behind IAH are complex and varied. It is therefore challenging to identify a single effective therapeutic strategy. In this review, we closely examine the efficacy and feasibility of a myriad of pharmaceutical interventions in preventing and treating IAH as described in clinical and preclinical studies. Pharmaceutical agents outlined include N-acetyl cysteine, GABA A receptor blockers, opioid receptor antagonists, AMP activated protein kinase agonists, potassium channel openers, dehydroepiandrosterone, metoclopramide, antiadrenergic agents, antidiabetic agents and glucagon.

Sobrerol: New Perspectives to Manage Patients with Frequent Respiratory Infections

Respiratory tract infections (RTIs) are usually characterized by mucus hypersecretion. This condition may worsen and prolong symptoms and signs. For this reason, reducing mucus production and improving mucus removal represent relevant aspects of managing patients with RTIs. In this regard, mucoactive drugs may be effective. Mucoactive agents constitute a large class of compounds characterized by different mechanisms of action. Sobrerol is a monoterpene able to fluidify mucus, increase mucociliary clearance, and exert antioxidant activity. Sobrerol is available in various formulations (granules, syrup, nebulized, and suppository). Sobrerol has been on the market for over 50 years. Therefore, the present article revised the evidence concerning this compound and proposed new possible strategies. The literature analysis showed that several studies investigated the efficacy and safety of sobrerol in acute and chronic RTIs characterized by mucus hyperproduction. Seven pediatric studies have been conducted with favorable outcomes. However, the regulatory agencies recently reduced the treatment duration to three days. Therefore, a future study will test the hypothesis that a combination of oral and topical sobrerol could benefit children and adults with frequent respiratory tract infections. The rationale of this new approach is based on the concept that mucus accumulation could be a risk factor for increased susceptibility to infections.

HIV-1 Tat-mediated microglial ferroptosis involves the miR-204–ACSL4 signaling axis

This study was focused on exploring the role of the HIV-1 Tat protein in mediating microglial ferroptosis. Exposure of mouse primary microglial cells (mPMs) to HIV-1 Tat protein resulted in induction of ferroptosis, which was characterized by increased expression of Acyl-CoA synthetase long-chain family member 4 (ACSL4), in turn, leading to increased generation of oxidized phosphatidylethanolamine, elevated levels of lipid peroxidation, upregulated labile iron pool (LIP) and ferritin heavy chain-1 (FTH1), decreased glutathione peroxidase-4 and mitochondrial outer membrane rupture. Also, inhibition of ferroptosis by ferrostatin-1 (Fer-1) or deferoxamine (DFO) treatment suppressed ferroptosis-related changes in mPMs. Similarly, the knockdown of ACSL4 by gene silencing also inhibited ferroptosis induced by HIV-1 Tat. Furthermore, increased lipid peroxidation resulted in increased release of proinflammatory cytokines, such as TNFα, IL6, and IL1β and microglial activation. Pretreatment of mPMs with Fer-1 or DFO further blocked HIV-1 Tat-mediated microglial activation in vitro and reduced the expression and release of proinflammatory cytokines. We identified miR-204 as an upstream modulator of ACSL4, which was downregulated in mPMs exposed to HIV-1 Tat. Transient transfection of mPMs with miR-204 mimics reduced the expression of ACSL4 while inhibiting HIV-1 Tat-mediated ferroptosis and the release of proinflammatory cytokines. These in vitro findings were further validated in HIV-1 transgenic rats as well as HIV + ve human brain samples. Overall, this study underscores a novel mechanism(s) underlying HIV-1 Tat-mediated ferroptosis and microglial activation involving miR-204-ACSL4 signaling.

Bromodomains in Human-Immunodeficiency Virus-Associated Neurocognitive Disorders: A Model of Ferroptosis-Induced Neurodegeneration

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) comprise a group of illnesses marked by memory and behavioral dysfunction that can occur in up to 50% of HIV patients despite adequate treatment with combination antiretroviral drugs. Iron dyshomeostasis exacerbates HIV-1 infection and plays a major role in Alzheimer's disease pathogenesis. In addition, persons living with HIV demonstrate a high prevalence of neurodegenerative disorders, indicating that HAND provides a unique opportunity to study ferroptosis in these conditions. Both HIV and combination antiretroviral drugs increase the risk of ferroptosis by augmenting ferritin autophagy at the lysosomal level. As many viruses and their proteins exit host cells through lysosomal exocytosis, ferroptosis-driving molecules, iron, cathepsin B and calcium may be released from these organelles. Neurons and glial cells are highly susceptible to ferroptosis and neurodegeneration that engenders white and gray matter damage. Moreover, iron-activated microglia can engage in the aberrant elimination of viable neurons and synapses, further contributing to ferroptosis-induced neurodegeneration. In this mini review, we take a closer look at the role of iron in the pathogenesis of HAND and neurodegenerative disorders. In addition, we describe an epigenetic compensatory system, comprised of bromodomain-containing protein 4 (BRD4) and microRNA-29, that may counteract ferroptosis by activating cystine/glutamate antiporter, while lowering ferritin autophagy and iron regulatory protein-2. We also discuss potential interventions for lysosomal fitness, including ferroptosis blockers, lysosomal acidification, and cathepsin B inhibitors to achieve desirable therapeutic effects of ferroptosis-induced neurodegeneration.

Combating Oxidative Stress and Inflammation in COVID-19 by Molecular Hydrogen Therapy: Mechanisms and Perspectives

COVID-19 is a widespread global pandemic with nearly 185 million confirmed cases and about four million deaths. It is caused by an infection with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which primarily affects the alveolar type II pneumocytes. The infection induces pathological responses including increased inflammation, oxidative stress, and apoptosis. This situation results in impaired gas exchange, hypoxia, and other sequelae that lead to multisystem organ failure and death. As summarized in this article, many interventions and therapeutics have been proposed and investigated to combat the viral infection-induced inflammation and oxidative stress that contributes to the etiology and pathogenesis of COVID-19. However, these methods have not significantly improved treatment outcomes. This may partly be attributable to their inability at restoring redox and inflammatory homeostasis, for which molecular hydrogen (H2), an emerging novel medical gas, may complement. Herein, we systematically review the antioxidative, anti-inflammatory, and antiapoptotic mechanisms of H2. Its small molecular size and nonpolarity allow H2 to rapidly diffuse through cell membranes and penetrate cellular organelles. H2 has been demonstrated to suppress NF-κB inflammatory signaling and induce the Nrf2/Keap1 antioxidant pathway, as well as to improve mitochondrial function and enhance cellular bioenergetics. Many preclinical and clinical studies have demonstrated the beneficial effects of H2 in varying diseases, including COVID-19. However, the exact mechanisms, primary modes of action, and its true clinical effects remain to be delineated and verified. Accordingly, additional mechanistic and clinical research into this novel medical gas to combat COVID-19 complications is warranted.

N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks)

OBJECTIVE

To review the clinical usefulness of N-acetylcysteine (NAC) as treatment or adjunctive therapy in a number of medical conditions. Use in Tylenol overdose, cystic fibrosis, and chronic obstructive lung disease has been well documented, but there is emerging evidence many other conditions would benefit from this safe, simple, and inexpensive intervention. Quality of Evidence. PubMed, several books, and conference proceedings were searched for articles on NAC and health conditions listed above reviewing supportive evidence. This study uses a traditional integrated review format, and clinically relevant information is assessed using the American Family Physician Evidence-Based Medicine Toolkit. A table summarizing the potential mechanisms of action for N-acetylcysteine in these conditions is presented. Main Message. N-acetylcysteine may be useful as an adjuvant in treating various medical conditions, especially chronic diseases. These conditions include polycystic ovary disease, male infertility, sleep apnea, acquired immune deficiency syndrome, influenza, parkinsonism, multiple sclerosis, peripheral neuropathy, stroke outcomes, diabetic neuropathy, Crohn's disease, ulcerative colitis, schizophrenia, bipolar illness, and obsessive compulsive disorder; it can also be useful as a chelator for heavy metals and nanoparticles. There are also a number of other conditions that may show benefit; however, the evidence is not as robust.

CONCLUSION

The use of N-acetylcysteine should be considered in a number of conditions as our population ages and levels of glutathione drop. Supplementation may contribute to reducing morbidity and mortality in some chronic conditions as outlined in the article.

Neuroimmune Mechanisms as Novel Treatment Targets for Substance Use Disorders and Associated Comorbidities

Recent studies examining the neurobiology of substance abuse have revealed a significant role of neuroimmune signaling as a mechanism through which drugs of abuse induce aberrant changes in synaptic plasticity and contribute to substance abuse-related behaviors. Immune signaling within the brain and the periphery critically regulates homeostasis of the nervous system. Perturbations in immune signaling can induce neuroinflammation or immunosuppression, which dysregulate nervous system function including neural processes associated with substance use disorders (SUDs). In this review, we discuss the literature that demonstrates a role of neuroimmune signaling in regulating learning, memory, and synaptic plasticity, emphasizing specific cytokine signaling within the central nervous system. We then highlight recent preclinical studies, within the last 5 years when possible, that have identified immune mechanisms within the brain and the periphery associated with addiction-related behaviors. Findings thus far underscore the need for future investigations into the clinical potential of immunopharmacology as a novel approach toward treating SUDs. Considering the high prevalence rate of comorbidities among those with SUDs, we also discuss neuroimmune mechanisms of common comorbidities associated with SUDs and highlight potentially novel treatment targets for these comorbid conditions. We argue that immunopharmacology represents a novel frontier in the development of new pharmacotherapies that promote long-term abstinence from drug use and minimize the detrimental impact of SUD comorbidities on patient health and treatment outcomes.

Bottom-up analysis of emergent properties of N-acetylcysteine as an adjuvant therapy for COVID-19

N-acetylcysteine (NAC) is an abundantly available antioxidant with a wide range of antidotal properties currently best studied for its use in treating acetaminophen overdose. It has a robustly established safety profile with easily tolerated side effects and presents the Food and Drug Administration's approval for use in treating acetaminophen overdose patients. It has been proven efficacious in off-label uses, such as in respiratory diseases, heart disease, cancer, human immunodeficiency virus infection, and seasonal influenza. Clinical trials have recently shown that NAC's capacity to replenish glutathione stores may significantly improve coronavirus disease 2019 (COVID-19) outcomes, especially in high risk individuals. Interestingly, individuals with glucose 6-phosphate dehydrogenase deficiency have been shown to experience even greater benefit. The same study has concluded that NAC's ability to mitigate the impact of the cytokine storm and prevent elevation of liver enzymes, C-reactive protein, and ferritin is associated with higher success rates weaning from the ventilator and return to normal function in COVID-19 patients. Considering the background knowledge of biochemistry, current uses of NAC in clinical practice, and newly acquired evidence on its potential efficacy against COVID-19, it is worthwhile to investigate further whether this agent can be used as a treatment or adjuvant for COVID-19.

Glutathione Deficiency in HIV-1-Infected Children with Short Stature

Objective This study was aimed to determine if glutathione (GSH) deficiency occurs in children with HIV infection and whether GSH deficiency is associated with HIV-related short stature.

Methods We conducted a cross-sectional study with two age-matched comparison groups in an inner city hospital-based pediatric AIDS/HIV outpatient clinic. Ten perinatally HIV-infected children aged 6 to 49 months with short stature (height–age percentile ≤5) were studied together with age-matched 10 HIV-infected children with normal height and 10 HIV-seronegative children with normal height. Total erythrocyte GSH (GSH and GSH disulfide) levels were determined by a modification of the 5,5′-dithiobis-2-nitrobenzoic acid glutathione disulfide reductase method. Other measures included complete blood counts, lymphocyte subset analysis, plasma albumin, cholesterol, vitamins A and E, and determination of HIV disease stage.

Discussion Erythrocyte GSH levels were lower in HIV-infected children with short stature (mean ± standard deviation [SD]: 0.639 µmol/mL ± 0.189) compared with HIV-infected children with normal height (mean ± SD: 0.860 µmol/mL ± 0.358; p < 0.05) and HIV-negative controls (mean ± SD: 0.990 µmol/mL ± 0.343; p < 0.05). Plasma levels of cholesterol, albumin, and vitamins A and E did not differ between the short-stature group and either the HIV-infected normal-height group or HIV-negative controls.

Conclusion These results demonstrate a GSH deficiency in HIV-infected children with short stature and support the hypothesis that GSH balance is important in growth among HIV-infected children.

Effect of pluronic block polymers and N-acetylcysteine culture media additives on growth rate and fatty acid composition of six marine microalgae species

Abstract

The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an ~27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture.

Key points

• Single and combined NAC and pluronic F127 culture media supplementation significantly enhanced the productivity of Chaetoceros calcitrans and Chaetoceros muelleri cultures.

• Culture media enrichments with NAC and F127 can increase omega-3-fatty acid content of algal biomass.

• Microalgae grown in NAC- and pluronic F127-supplemented culture media are suitable for live-feed applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-021-11147-8.

N-acetylcysteine and coronavirus disease 2019: May it work as a beneficial preventive and adjuvant therapy? A comprehensive review study

BACKGROUND

Coronaviruses are major pathogens of respiratory system causing different disorders, including the common cold, Middle East respiratory syndrome, and severe acute respiratory syndrome. Today's global pandemic coronavirus disease 2019 (COVID-19) has high mortality rate, with an approximate of 20% in some studies, and is 30-60 times more fatal than the common annual influenza, However, there is still no gold standard treatment for it. N-acetylcysteine (NAC) is a well-known multi-potential drug with hypothetically probable acceptable effect on COVID-related consequences, which we completely focused in this comprehensive review.

MATERIALS AND METHODS

PubMed, Scopus, Science Direct, and Google Scholar have been searched. Study eligibility criteria: efficacy of NAC in various subclasses of pathogenic events which may occur during COVID-19 infection. Efficacy of NAC for managing inflammatory or any symptoms similar to symptoms of COVID-19 was reviewed and symptom improvements were assessed.

RESULTS

Randomized clinical trials introduced NAC as an antioxidant glutathione analog and detoxifying agent promoted for different medical conditions and pulmonary disorders to alleviate influenza and reduce mortality by 50% in influenza-infected animals. The beneficial effects of NAC on viral disorders, including Epstein-Barr virus, HIV and hepatitis, and well-known vital organ damages were also exist and reported.

CONCLUSION

We classified the probable effects of NAC as oxidative-regulatory and apoptotic-regulatory roles, antiviral activities, anti-inflammatory roles, preventive and therapeutic roles in lung disorders and better oxygenation functions, supportive roles in intensive care unit admitted patients and in sepsis, positive role in other comorbidities and nonpulmonary end-organ damages or failures and even in primary COVID-associated cutaneous manifestations. Based on different beneficial effects of NAC, it could be administered as a potential adjuvant therapy for COVID-19 considering patient status, contraindications, and possible drug-related adverse events.

Human Immunodeficiency Virus Type 1 and Methamphetamine-Mediated Mitochondrial Damage and Neuronal Degeneration in Human Neurons

Methamphetamine, a potent psychostimulant, is a highly addictive drug commonly used by persons living with HIV (PLWH), and its use can result in cognitive impairment and memory deficits long after its use is discontinued. Although the mechanism(s) involved with persistent neurological deficits is not fully known, mitochondrial dysfunction is a key component in methamphetamine neuropathology. Specific mitochondrial autophagy (mitophagy) and mitochondrial fusion and fission are protective quality control mechanisms that can be dysregulated in HIV infection, and the use of methamphetamine can further negatively affect these protective cellular mechanisms. Here, we observed that treatment of human primary neurons (HPNs) with methamphetamine and HIV gp120 and Tat increase dynamin-related protein 1 (DRP1)-dependent mitochondrial fragmentation and neuronal degeneration. Methamphetamine and HIV proteins increased microtubule-associated protein 1 light chain 3 beta-II (LC3B-II) lipidation and induced sequestosome 1 (SQSTM1, p62) translocation to damaged mitochondria. Additionally, the combination inhibited autophagic flux, increased reactive oxygen species (ROS) production and mitochondrial damage, and reduced microtubule-associated protein 2 (MAP2) dendrites in human neurons. N-Acetylcysteine (NAC), a strong antioxidant and ROS scavenger, abrogated DRP1-dependent mitochondrial fragmentation and neurite degeneration. Thus, we show that methamphetamine combined with HIV proteins inhibits mitophagy and induces neuronal damage, and NAC reverses these deleterious effects on mitochondrial function.IMPORTANCE Human and animal studies show that HIV infection, combined with the long-term use of psychostimulants, increases neuronal stress and the occurrence of HIV-associated neurocognitive disorders (HAND). On the cellular level, mitochondrial function is critical for neuronal health. In this study, we show that in human primary neurons, the combination of HIV proteins and methamphetamine increases oxidative stress, DRP1-mediated mitochondrial fragmentation, and neuronal injury manifested by a reduction in neuronal network and connectivity. The use of NAC, a potent antioxidant, reversed the neurotoxic effects of HIV and methamphetamine, suggesting a novel approach to ameliorate the effects of HIV- and methamphetamine-associated cognitive deficits.

Protonation Equilibria of N-Acetylcysteine

The acid base protonation equilibria of N-acetylcysteine (Nac) and its equilibrium constants in water solutions were determined by the Hyperquad 2008 software assessment from the pH potentiometry data, which provides a diversity of statistics presentations. The effect of a number of organic solvents on the acid base protonation processes was also examined. The solution equilibria of N-acetylcysteine (Nac) were studied at T = 298.15 K in water (w ₁) + organic liquid mixtures [100 w ₂ = 0, 20, 40, 60, and 80%] with an ionic strength of I = 0.16 mol·dm^-3 NaNO₃. Also, the organic solvent's influence was studied based on the Kamlet-Taft linear solvation energy relationship. The experimental results were compared with theoretical ones obtained via the Gaussian 09 calculation computer program. The protonation equilibria of Nac were found to be important in the progress of separation systems in aqueous and non-aqueous ionic solutions. Nac showed a likely good metal dibasic chelating bioligand as the DFT calculations proved two binding sites. Spectrophotometry evaluation was also done for N-acetylcysteine bioligands at various pH values in water solutions then its absorbance ratio was measured.

Cryopreservation of stallion semen: Effect of adding antioxidants to the freezing medium on sperm physiology

Cryopreservation of stallion semen has not reached the level of efficiency and positive results described in other species. This is mainly due to the greater sensitivity of stallion sperm to the freezing process, showing higher rates of oxidative stress and plasma membrane damage, which trigger the activation of several cell damage pathways that ultimately culminate in DNA fragmentation and cell death. Therefore, finding molecules that improve the efficiency of this technique in stallion by preventing oxidative stress and cell damage is required. Thus, the aim of the present study was to evaluate the effect of adding three antioxidants (MnTBAP, NAC and FeTPPS) to the freezing medium on the quality and functional parameters of stallion sperm. Semen samples from three stallions frozen with the antioxidants were evaluated in two conditions: (a) adding the antioxidants before freezing, and (b) before and after freezing. Plasma membrane integrity, mitochondrial membrane potential, lipid peroxidation, intracellular ROS levels, membrane lipid disorder, DNA damage, sperm motility and binding to the zona pellucida were assessed. The results showed that MnTBAP was the antioxidant treatment that best controlled the oxidative stress process and post-thaw cell damage, showing higher plasma membrane integrity, mitochondrial membrane potential, sperm motility, number of spermatozoa bound to the zona pellucida of bovine oocytes and lower lipid disorder. Additionally, it was determined that a second post-thaw application of antioxidants is detrimental since induced higher cell damage and lower sperm motility, without showing any beneficial effect on the spermatozoa.

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism.

A novel antiviral inhibits Zika virus infection while increasing intracellular glutathione biosynthesis in distinct cell culture models

We investigated the effects of a specific free-form amino acids formulation on Zika virus replication in two different cell culture model systems, one representative of humans and the other of Old World primates from whom Zika virus was first isolated. Here we present data demonstrating that the formulation of the specific free-form amino acid (FFAAP), comprising cystine, glycine, and a glutamate source, along with a minute concentration of selenium inhibited Zika virus replication by up to 90% with an ED₉₀ (effective dose at which 90% of a dose of Zika virus was inhibited) of 2.5 mM in human cells and 4 mM Vero cells. The ED₉₀ concentration of precursors was innocuous for uninfected cells, but resulted in reduced Zika virus replication by up to 90% at 2-5 mM concentrations in nonhuman primate cells and at 1-3 mM concentration in human placental cells. Two important observations were forthcoming: 1) Zika virus production was decreased by up to 90% in Vero and JEG-3 cells treated with FFAAP (ED₉₀ 4.0 mM, and 2.5 mM, respectively) throughout 48-72 h of post infection (hpi) compared to untreated infected cells and 2) Zika virus requires intracellular glutathione for replication in human placental cells, while showing enhanced replication in Vero cells with no glutathione. Relative increases in intracellular glutathione biosynthesis followed FFAAP treatment but blocking intracellular biosynthesis of glutathione in human cells resulted in virus inhibition in human placental cells. The blockade of biosynthesis actually increased Zika virus replication in Vero cells. These findings identify an efficacious inhibitor, FFAAP, of Zika virus replication in both human and nonhuman primate cells, while providing novel insight into the different roles of intracellular glutathione in Zika virus replication.

HIV/HAART-associated oxidative stress is detectable by metabonomics

Chronic human immunodeficiency virus (HIV) infection, separately and in combination with highly active antiretroviral therapy (HAART) is closely associated with oxidative stress (OS). Most studies demonstrating redox imbalances in HIV-infected individuals have done so using conventional biochemical methodologies. The limited simultaneous detection of multiple OS markers within one sample is a major drawback of these methodologies and can be addressed through the use of metabonomics. HIV-metabonomic studies utilizing biofluids from HAART cohorts as the investigative source, are on the increase. Data from many of these studies identified metabolic markers indicative of HIV-induced OS, usually as an outcome of an untargeted metabonomics study. Untargeted studies cast a wide net for any and all detectable metabolites in complex mixtures. Given the prevalence of OS during HIV infection and antiviral treatment, it is perhaps not surprising that indicators of this malady would become evident during metabolite identification. At times, targeted studies for specific (non-OS) metabolites would also yield OS markers as an outcome. This review examines the findings of these studies by first providing the necessary background information on OS and the main ways in which free radicals/reactive oxygen species (ROS) produced during OS, cause biomolecular damage. This is followed by information on the biomarkers which come about as a result of free radical damage and the techniques used for assaying these stress indicators. The established links between elevated ROS and lowered antioxidants during HIV infection and the subsequent use of HAART is then presented followed by a review of the OS markers detected in HIV metabonomic studies to date. We identify gaps in HIV/HAART-associated OS research and finally suggest how these research gaps can be addressed through metabonomic analysis, specifically targeting the multiple markers of HIV-induced OS.

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.

Golgi stress response reprograms cysteine metabolism to confer cytoprotection in Huntington's disease

Golgi stress response is emerging as a physiologic process of comparable importance to endoplasmic reticulum (ER) and mitochondrial stress responses. However, unlike ER stress, the identity of the signal transduction pathway involved in the Golgi stress response has been elusive. We show that the Golgi stressor monensin acts via the PKR-like ER kinase/Activating Transcription Factor 4 pathway. ATF4 is the master regulator of amino acid metabolism, which is induced during amino acid depletion and other forms of stress. One of the genes regulated by ATF4 is the biosynthetic enzyme for cysteine, cystathionine γ-lyase (CSE), which also plays central roles in maintenance of redox homeostasis. Huntington's disease (HD), a neurodegenerative disorder, is associated with disrupted cysteine metabolism caused by depletion of CSE leading to abnormal redox balance and stress response. Thus, restoring CSE function and cysteine disposition may be beneficial in HD. Accordingly, we harnessed the monensin-ATF4-signaling cascade to stimulate CSE expression by preconditioning cells with monensin, which restores cysteine metabolism and an optimal stress response in HD. These findings have implications for treatment of HD and other diseases associated with redox imbalance and dysregulated ATF4 signaling.

Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione

Glutathione (GSH) is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs)-immobilized, hierarchically ordered titanium dioxide (TiO₂) porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO₂ electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO₂ nanotubes are analyzed using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Interestingly, nanocomposites of TiO₂ with Au NPs is prepared in an effort to alter the intrinsic properties of TiO₂, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO₂ electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO₂ electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV) and chronoamperometry (CA). Several parameters such as sensitivity, selectivity, stability, limit of detection, etc are investigated. In addition, Au NPs dispersed in aqueous medium are also explored for naked-eye detection of GSH using UV-visible spectroscopy in order to compare the performance of the proposed sensor. Our studies clearly indicate that these materials could potentially be used for GSH sensing applications.

Determination of cysteine and glutathione based on the inhibition of the dinuclear Cu(II)-catalyzed luminol-H2O2 chemiluminescence reaction

The catalyzed luminol chemiluminescent reaction has received a great amount of attention because of its high sensitivity and low background signal which make the reaction an attractive analytical chemistry tool. The present study, introduces the beneficial catalytic effects of dinuclear Cu(II) complex [Cu2L2(TAE)]X2, where TAE=tetraacetylethane; L=N,N(')-dibenzylethylenediamine and X=ClO4 on the luminol chemiluminescent reaction as a novel probe for the determination of glutathione (GSH) and L-cysteine (CySH) in human serum and urine. The [Cu2L2(TAE)]X2 has exhibited highly efficient catalytic activity of luminol CL as an artificial peroxidase model at pH as low as 7.5 in water in the presence of H2O2⋅GSH and CySH can induce a sharp decrease in CL intensity from the [Cu2L2(TAE)]X2-catalyzed luminol system. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the concentrations of GSH and CySH in the range of 1.0×10(-7)-1.0×10(-4) M, with detection limits (S/N=3) of 2.7×10(-8) and 6.8×10(-8) M and RSD<4.2% (n=7) for GSH and CySH, respectively.

Redox regulation of T-cell function: from molecular mechanisms to significance in human health and disease

Reactive oxygen species (ROS) are thought to have effects on T-cell function and proliferation. Low concentrations of ROS in T cells are a prerequisite for cell survival, and increased ROS accumulation can lead to apoptosis/necrosis. The cellular redox state of a T cell can also affect T-cell receptor signaling, skewing the immune response. Various T-cell subsets have different redox statuses, and this differential ROS susceptibility could modulate the outcome of an immune response in various disease states. Recent advances in T-cell redox signaling reveal that ROS modulate signaling cascades such as the mitogen-activated protein kinase, phosphoinositide 3-kinase (PI3K)/AKT, and JAK/STAT pathways. Also, tumor microenvironments, chronic T-cell stimulation leading to replicative senescence, gender, and age affect T-cell susceptibility to ROS, thereby contributing to diverse immune outcomes. Antioxidants such as glutathione, thioredoxin, superoxide dismutase, and catalase balance cellular oxidative stress. T-cell redox states are also regulated by expression of various vitamins and dietary compounds. Changes in T-cell redox regulation may affect the pathogenesis of various human diseases. Many strategies to control oxidative stress have been employed for various diseases, including the use of active antioxidants from dietary products and pharmacologic or genetic engineering of antioxidant genes in T cells. Here, we discuss the existence of a complex web of molecules/factors that exogenously or endogenously affect oxidants, and we relate these molecules to potential therapeutics.

N-acetylcysteine reverses cardiac myocyte dysfunction in HIV-Tat proteinopathy

HIV cardiomyopathy remains highly prevalent among the estimated 33 million HIV-infected individuals worldwide. This is particularly true in developing countries. Potential mechanisms responsible for myocardial dysfunction following HIV infection include direct effects of HIV proteins. We have previously reported that cardiac myocyte-specific expression of HIV-Tat (Tat) results in a murine cardiomyopathy model. We now report that Tat exhibits decreased myocardial ATP [wild type (WT) vs. Tat transgenic (TG), P < 0.01] and myocyte GSH levels (WT vs. TG, P < 0.01), decreased GSH/GSSG ratio (WT vs. TG, P < 0.01), increased H(2)O(2) levels (WT vs. TG, P < 0.05), and increased catalase (TG vs. WT, P < 0.05) and GPX1 (glutathione peroxidase 1) activities (WT vs. TG, P < 0.05), blunted cardiac myocyte positive inotropy (% peak shortening, WT vs. TG, P < 0.01; +dl/dt, WT vs. TG, P < 0.01) and negative inotropy (-dl/dt, WT vs. TG, P < 0.01), and blunted inotropic responses to Ca(2+) (P < 0.01, for each) and shortened anatomical and functional survival in vitro (P < 0.01). The sulfhydryl donor, N-acetylcysteine (NAC; 10(-4) M), completely reversed both the positive and negative inotropic defects in Tat; increased GSH (P < 0.01) and GSH/GSSG (P < 0.01); reversed H(2)O(2) level (P < 0.05) and GPX1 activity (P < 0.05); and normalized the blunted inotropic response to Ca(2+) (P < 0.01). NAC (10(-7)) M normalized duration of contractile function from <40 min to >120 min (P < 0.01), with no effect on GSH and GSH/GSSG. NAC (10(-4) M) reverses cardiac myocyte dysfunction and markers of oxidative stress. NAC (10(-7) M) enhances myocyte function independent of changes in glutathione. Elucidating the molecular mechanisms involved in the GSH-dependent and GSH-independent salutary effects of NAC should identify novel therapeutic targets for myocardial proteinopathies recently appreciated in human cardiomyopathies.

Differential modulation of apoptotic gene expression by N-acetyl-L-cysteine in Leydig cells stimulated persistently with hCG in vivo

The present study was designed to investigate the molecular mechanisms of NAC (150 mg/kg bw twice/week) action in vivo under repeated hCG (100 IU/rat/day) stimulation to adult rats. Leydig cell refractoriness led to a significant decline in serum testosterone and intracellular cAMP by day 30 of chronic hCG intervention which improved significantly following NAC co-administration. It inhibited the rise in lipid peroxidation, improved the activity of antioxidant enzymes along with intracellular glutathione and total antioxidant capacity in the target cells. Leydig cell apoptosis declined significantly (P<0.001) with down-regulation of upstream, Fas, FasL, caspase-8, Bax and caspase-9, JNK/pJNK and downstream caspase-3 and PARP. On the other hand, anti-apoptotic Bcl2, NF-kβ, and Akt were up-regulated. Taken together, the above findings indicate that the specificity of NAC action was not restricted to regulating marker proteins in the extrinsic and JNK pathways as seen in vitro but extended to include intrinsic pathway of metazoan apoptosis as well.

Astrocytes survive chronic infection and cytopathic effects of the ts1 mutant of the retrovirus Moloney murine leukemia virus by upregulation of antioxidant defenses

The ts1 mutant of Moloney murine leukemia virus (MoMuLV) induces a neurodegenerative disease in mice, in which glial cells are infected by the retrovirus but neurons are not. ts1 infection of primary astrocytes, or of the immortalized astrocytic cell line C1, results in accumulation of the ts1 gPr80(env) envelope protein in the endoplasmic reticulum (ER), with ER and oxidative stress. Notably, only about half of the infected astrocytes die in these cultures, while the other half survive, continue to proliferate, and continue to produce virus. To determine how these astrocytes survive ts1 infection in culture, we established a chronically infected subline of the living cells remaining after the death of all acutely infected cells in an infected C1 cell culture (C1-ts1-S). We report here that C1-ts1-S cells proliferate more slowly, produce less virus, show reduced H2O2 levels, increase their uptake of cystine, and maintain higher levels of intracellular GSH and cysteine compared to acutely infected or uninfected C1 cells. C1-ts1-S cells also upregulate their thiol antioxidant defenses by activation of the transcription factor NF-E2-related factor 2 (Nrf2) and its target genes. Interestingly, despite maintenance of higher levels of intracellular reduced thiols, C1-ts1-S cells are more sensitive to cystine deprivation than uninfected C1 cells. We conclude that some ts1-infected astrocytes survive and adapt to virus-induced oxidative stress by successfully mobilizing their thiol redox defenses.

Molecular and cellular mechanisms of neuronal cell death in HIV dementia

The deaths of neurons, astrocytes and endothelial cells have been described in patients with HIV (human immunodeficiency virus) dementia. HIV-1 does not infect neurons; instead, neurotoxic substances shed by infected glia and macrophages can induce a form of programmed cell death called apoptosis in neurons. These neurotoxins include the HIV-1 proteins Tat and gp120, as well as pro-inflammatory cytokines, chemokines, excitotoxins and proteases. In this article we review the evidence for apoptosis of various cell types within the brain of HIV-infected patients, and describe in vitro and in vivo experimental studies that have elucidated the mechanisms by which HIV causes apoptosis of brain cells.

Enzymatic method with polyphenol oxidase for the determination of cysteine and N-acetylcysteine

Thiols, such as cysteine and N-acetylcysteine, are included in many pharmaceutical products for their mucolytic properties. The method described here uses mushroom polyphenol oxidase (PPO) to determine two thiols and consists of measuring the lag period in the formation of the product generated as PPO acts on o-diphenol in the presence of a thiol. In the experimental conditions, o-quinone is formed enzymatically and then reacts stoichiometrically with the thiol, originating the corresponding thiol-diphenol adduct, which does not absorb visible light. Once the thiol has been used up, the o-quinone can be observed in the medium. It must be borne in mind that the inhibition of PPO is practically null at low concentrations of thiol, and the only effect observed is the formation of the thiol-diphenol adduct. In the following, an exact kinetic method capable of rapidly and accurately assaying thiols with PPO and o-diphenol is optimized and is shown to be a straightforward way of calculating thiol concentration. The method has been successfully applied to the determination of cysteine in model solutions and of N-acetylcysteine in pharmaceutical products.

New synthetic glutathione derivatives with increased antiviral activities

A series of glutathione (GSH) derivatives with aliphatic chains of different lengths, coupled by peptides bound to the alpha-NH2 group of Glu, were synthesized. When added to several cell lines, the C6 (n-hexanoyl), C8 (n-octanoyl) and C12 (n-dodecanoyl) derivatives were toxic while the C2 (nethanoyl) and C4 (n-butanoyl) derivatives were not. Preliminary experiments were performed to investigate the potential antiviral activity of the C2 and C4 derivatives compared to GSH. The C4 derivative was the most potent and fully characterized. GSH-C4 is a poor substrate of GSH metabolizing enzymes; once oxidized by disulphide-bound formation, C4 is slowly reduced by GSH-reductase. GSH-C4 completely abrogated Sendai virus replication at 7.5 mM with an EC50 of 3.6 mM, compared to 7.5 mM for GSH. GSH-C4 completely inhibited herpes simplex virus (HSV-1) virus production in Vero cells at 10 mM, while the same dose of GSH caused only a 2.5 log10 reduction. Furthermore, the GSH-C4 treatment (7.5 mM) was able to markedly reduce the cytopathic effect of HSV-1 in Vero cells. Thus, GSH derivatives with increased hydrophobic properties are more effective antiviral agents against Sendai and HSV-1 viruses than GSH, suggesting their usefulness in antiviral therapy.

Activation of transcription factor Nrf-2 and its downstream targets in response to moloney murine leukemia virus ts1-induced thiol depletion and oxidative stress in astrocytes

The neuroimmunodegenerative syndrome that develops in mice infected with ts1, a mutant of Moloney murine leukemia virus, resembles human AIDS. Both ts1 and human immunodeficiency virus type 1 infect astrocytes, microglia, and oligodendrocytes but do not infect neurons. Oxidative stress has been implicated in the neuropathology of AIDS dementia and other neurodegenerative diseases. We report here that ts1 infection of astrocytes (both transformed C1 cells and primary cultures) also induces thiol (i.e., glutathione and cysteine) depletion and reactive oxygen species (ROS) accumulation, events occurring in parallel with viral envelope precursor gPr80(env) accumulation and upregulated expression of endoplasmic reticulum chaperones GRP78 and GRP94. Furthermore, ts1-infected astrocytes mobilize their thiol redox defenses by upregulating levels of the Nrf-2 transcription factor, as well its targets, the xCT cystine/glutamate antiporter, gamma-glutamylcysteine ligase, and glutathione peroxidase. Depleting intracellular thiols by treating uninfected astrocytes with buthionine sulfoximine (BSO), a glutathione synthesis inhibitor, or by culturing in cystine-deficient medium, also induces ROS accumulation, activates Nrf-2, and upregulates Nrf-2 target gene expression in these astrocytes. Overexpression of Nrf-2 in astrocytes specifically increases expression of the above thiol synthesis-related proteins. Further treatment with BSO or N-acetylcysteine in transfected cells modulates this expression. Thiol depletion also accelerates cell death, while thiol supplementation promotes survival of ts1-infected cells. Together, our results indicate that ts1 infection of astrocytes, along with ts1-induced gPr80(env) accumulation, endoplasmic reticulum stress, thiol depletion, and oxidative stress, accelerates cell death; in response to the thiol depletion and oxidative stress, astrocytes activate their Nrf-2-mediated thiol antioxidant defenses, promoting cell survival.

Lymphocyte proliferation and apoptosis in HIV-seropositive and healthy subjects during long-term ingestion of fruit juices or a fruit-vegetable-concentrate rich in polyphenols and antioxidant vitamins

OBJECTIVE

We investigated whether ingestion of polyphenols from fruit juices or a fruit-vegetable-concentrate affects lymphocyte proliferation and apoptosis in human immunodeficiency virus (HIV)-seropositive (HIV(+)) and HIV-seronegative (HIV(-)) subjects.

DESIGN

Randomized, prospective pilot intervention study.

SETTING

University of Bonn, Department of General Internal Medicine.

SUBJECTS

A total of 23 HIV(+) subjects from the HIV outpatient clinic, 18 HIV(-) controls.

INTERVENTIONS

Subjects ingested either 1 l of fruit juice or 30 ml of fruit-vegetable-concentrate daily for 16 weeks in addition to their regular diet. Lymphocyte proliferation and apoptosis were investigated in peripheral blood mononuclear cells at baseline, during 16-weeks of intervention, and after a 6-week washout. Proliferation was assessed by (3)H-thymidine incorporation and apoptosis by nuclear content as measured by flow cytometry.

RESULTS

Supplementation of fruit juices increased phytohemagglutinin-induced lymphocyte proliferation (mitotic index) in HIV(+) patients from 18+/-16 to 40+/-34 (P=0.004) and in healthy controls from 27+/-16 to 51+/-21 (P=0.016). Apoptosis was not affected in HIV(+) patients, but rose in healthy controls from 9+/-10 to 34+/-11 (apoptotic index; P=0.001). Intervention with concentrate did not significantly alter proliferation and apoptosis in HIV(+) and HIV(-) subjects.

CONCLUSIONS

Even though apoptosis did not change in HIV(+) subjects, ingestion of polyphenol-rich fruit juices might be favorable to HIV(+) patients due to enhanced proliferation, which could restore disturbances in T-cell homeostasis. In healthy controls, increased lymphocyte proliferation during juice consumption was counterbalanced by increased apoptosis.

Inflammatory cytokine response to Vibrio vulnificus elicited by peripheral blood mononuclear cells from chronic alcohol users is associated with biomarkers of cellular oxidative stress

Vibrio vulnificus is the leading cause of death in the United States associated with the consumption of raw seafood, particularly oysters. In epidemiological studies, primary septicemia and inflammation-mediated septic shock caused by V. vulnificus is strongly associated with liver disease, often in the context of chronic alcohol abuse. The present study was undertaken to determine whether clinical biomarkers of liver function or cellular oxidative stress are associated with peripheral blood mononuclear cell inflammatory cytokine responses to V. vulnificus. Levels of interleukin-1 beta (IL-1 beta), IL-6, IL-8, and tumor necrosis factor alpha elicited in response to V. vulnificus and measured in cell supernatants were not associated with the liver biomarkers aspartate aminotransferase (AST) or alanine aminotransferase (ALT) or the AST/ALT ratio. In contrast, reduced glutathione (GSH) levels were associated with the release of all four cytokines (IL-1 beta [R(2) = 0.382; P = 0.006], IL-6 [R(2) = 0.393; P = 0.005], IL-8 [R(2) = 0.487; P = 0.001], and TNF-alpha [R(2) = 0.292; P = 0.021]). Those individuals with below-normal GSH levels produced significantly less proinflammatory cytokines in response to V. vulnificus. We hypothesize that persons with markers for cellular oxidative stress have increased susceptibility to V. vulnificus septicemia.

Recent advances in the chemistry of parainfluenza-1 (Sendai) virus inhibitors

Purine and pyrimidine derivatives, antioxidants, fusion inhibitors, statins, prostaglandins, antibiotic nucleosides, inhibitors of Ca(2+) homeostasis, carbohydrate derivatives, antisense polynucleotides and chimeras, are described as inhibitors of parainfluenza-1 (Sendai) viral infections.

Human natural killer cell activity against porcine targets: modulation by control of the oxidation-reduction environment and role of adhesion molecule interactions

Xenotransplantation, especially using porcine sources, has been proposed as a means to alleviate the shortage of human organs for transplantation. NK cells appear to be important mediators of the xenogeneic immune responses, including the human anti-pig response. Having previously established the redox regulation of NK cell activity against tumor target cells, we now report that the interaction of human NK cells with porcine target cells is also regulated by redox. Thiol-deprivation strongly diminished the capacity of IL-2-activated human NK cells to kill porcine endothelial cells. This inhibition correlated with reduced proliferation and interferon (IFN)-gamma production by IL-2-activated NK cells. For fresh NK cells, pretreatment with diethyl maleate (DEM), which was used to deplete intracellular thiols, reduced lysis of porcine and human targets. Because many adhesion molecules exhibit interspecies recognition, we further investigated whether changes in expression of adhesion molecules might explain our observations. DEM treatment reduced the expression of CD11b and CD29 on fresh NK cells. Monoclonal antibody blocking studies showed that the combination of mAb to CD11b and CD18 reduced lytic activity against both PAEC as well as K562, although other qualitative differences were observed between the porcine and human target cells. These findings suggest that the oxidative stress-induced downregulation of CD18 may be important in modulating cytotoxic activity of fresh NK cells against PAEC and K562 targets through reduced formation of the CD11b/CD18 heterodimer. Thus, the appropriate manipulation of redox status may provide a means to enhance survival of non-human animal tissues in humans through modulation of adhesion molecule expression/interactions.

Disulfide exchange in domain 2 of CD4 is required for entry of HIV-1

CD4, a member of the immunoglobulin superfamily of receptors that mediates cell-cell interactions in the immune system, is the primary receptor for HIV-1. The extracellular portion of CD4 is a concatenation of four immunoglobulin-like domains, D1 to D4. The D1, D2 and D4 domains each contain a disulfide bond. We show here that the D2 disulfide bond is redox-active. The redox state of the thiols (disulfide versus dithiol) appeared to be regulated by thioredoxin, which is secreted by CD4(+) T cells. Locking the CD4 and the thioredoxin active-site dithiols in the reduced state with a hydrophilic trivalent arsenical blocked entry of HIV-1 into susceptible cells. These findings indicate that redox changes in CD4 D2 are important for HIV-1 entry and represent a new target for HIV-1 entry inhibitors.

Redox imbalance and its control in HIV infection

Human immunodeficiency virus (HIV)-infected individuals are suffering from systemic oxidative stress. Reactive oxygen species act as second messengers for the activation of nuclear factor-kappaB (NF-kappaB), which augments the replication of HIV. Intracellular levels of glutathione (GSH), a major cytosolic antioxidant, in T cells decrease during the disease progression. Another redox-regulating molecule, thioredoxin (TRX), is also transiently down-regulated in the cells by acute HIV infection. In contrast, plasma levels of TRX are elevated in the late stage of HIV infection. Intracellular GSH and plasma TRX can be biomarkers to predict the prognosis of the disease. N-Acetylcysteine (NAC), a prodrug of cysteine that is necessary for GSH synthesis, has been used for HIV infection to prevent the activation of NF-kappaB and the replication of HIV. NAC shows some beneficial effects for HIV-infected individuals, although the intracellular GSH levels in lymphocytes are not significantly restored. The control of imbalanced redox status by antioxidants may be beneficial for the quality of life in HIV infection even in the era after the effective therapy with protease inhibitors has been applied. Redox control will be an important therapeutic strategy for oxidative stress-associated disorders including HIV infection.

Redox control of EBV infection: prevention by thiol-dependent modulation of functional CD21/EBV receptor expression

CD21 serves as a receptor for the Epstein-Barr virus (EBV). In this report, surface expression of CD21 on B and T cells was shown to be suppressed by a thiol-antioxidant, N-acetylcysteine (NAC), in a dose- and time-dependent manner. In contrast, expression of other surface markers, CD25 and CD4 for T cells and CD19 and surface IgM for B cells, was not affected by NAC. When an EBV-negative B-cell line B104 was treated with NAC, the cells were not susceptible to infection with B95-8-derived EBV. The effect of NAC was shown to be irrelevant to the transcriptional levels of CD21 mRNA and the intracellular glutathione levels. Immunoprecipitation study revealed that NAC causes a loss of anti-CD21 monoclonal antibody (HB5) binding to both membrane and soluble CD21, suggesting that NAC modulates the structure of CD21. Other thiol-antioxidants, such as 2-mercaptoethanol, pyrrolidine dithiocarbamate, and glutathione, showed similar effect to NAC on CD21 expression. These results suggest the possible modulation of EBV infection via thiol-dependent redox control of CD21, and thiol-antioxidants may be good candidates for controlling EBV infection.

Plasma antioxidant capacity of HIV-seropositive and healthy subjects during long-term ingestion of fruit juices or a fruit-vegetable-concentrate containing antioxidant polyphenols

OBJECTIVE

To investigate whether antioxidant polyphenols from fruit juices or a fruit-vegetable-concentrate increase the plasma antioxidant capacity in HIV-infected and healthy subjects.

DESIGN

Twenty-three HIV-seropositive and 18 seronegative adults were randomized to ingest either 1 l of fruit juice or 30 ml fruit-vegetable-concentrate per day over 16 weeks in addition to their normal Western diet.

METHODS

Plasma antioxidant capacity was determined as Trolox equivalent antioxidant capacity (TEAC) at baseline, after 1 and 16 weeks of intervention, and after a 6 week washout.

RESULTS

There was no difference in plasma antioxidant capacity between HIV-infected and healthy subjects at baseline (P=0.1). After 16 weeks of intervention TEAC increased in HIV-positive subjects with both types of polyphenol supplementation (juice, 1.38+/-0.07 to 1.42+/-0.04 mM, P=0.034; concentrate, 1.40+/-0.09 to 1.46+/-0.08 mM, P=0.025). TEAC was not altered by either type of supplementation in HIV-seronegative subjects.

CONCLUSION

Plasma antioxidant capacity can be increased by long-term ingestion of polyphenols from fruit juices or fruit-vegetable-concentrate in HIV-seropositive but not in HIV-seronegative subjects.

SPONSORSHIP

This study was supported by a grant and Cellagon aurum from HG Berner GmbH, Altenholz, and fruit juices from Eckes Granini GmbH & Co. KG, Nieder-Olm.

Differential pattern in circulating nitrogen derivatives, lactoferrin, and anti-lactoferrin antibodies in HIV type 1 and HIV type 2 infections

HIV-1 infection is associated with a dramatic reduction in antioxidative molecules both at the cellular level and in the circulation. This is particularly so for lactoferrin, an iron-binding protein involved in natural defenses (antimicrobial and antiviral activities, etc.) and found in whole secretions, including milk and mucus. In addition to its ability to chelate iron ions, lactoferrin inhibits hydroxy radical formation and interacts with nitric oxide (NO). Levels of plasma lactoferrin decreased in HIV-1-infected patients in correlation with progression of the disease, and highly specific anti-lactoferrin autoantibodies increased. This profile was specific to HIV-1 infection; it was not found in HIV-2-infected patients. In parallel with the drop in lactoferrin, a marked increase in circulating nitrogen derivatives was observed in HIV-1-infected patients, whereas low levels were found in normal donors and in HIV-2-infected patients. These data suggested hyperstimulation of the NO pathway throughout HIV-1 but not HIV-2 infection. This overproduction of NO could play an important role in the development of AIDS symptoms and signs.