CD4 and CD8 T cells with high intracellular glutathione levels are selectively lost as the HIV infection progresses

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.

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.

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.

Immunogenetic studies of the hepatitis C virus infection in an era of pan-genotype antiviral therapies - Effective treatment is coming

What are the factors that influence human hepatitis C virus (HCV) infection, hepatitis status establishment, and disease progression? Firstly, one has to consider the genetic background of the host and HCV genotypes. The immunogenetic host profile will reflect how each infected individual deals with infection. Secondly, there are environmental factors that drive susceptibility or resistance to certain viral strains. These will dictate (I) the susceptibility to infection; (II) whether or not an infected person will promote viral clearance; (III) the immune response and the response profile to therapy; and (IV) whether and how long it would take to the development of HCV-associated diseases, as well as their severity. Looking at this scenario, this review addresses clinical aspects of HCV infection, following by an update of molecular and cellular features of the immune response against the virus. The evasion mechanisms used by HCV are presented, considering the potential role of exosomes in infection. Genetic factors influencing HCV infection and pathogenesis are the main topics of the article. Shortly, HLAs, MBLs, TLRs, ILs, and IFNLs genes have relevant roles in the susceptibility to HCV infection. In addition, ILs, IFNLs, as well as TLRs genes are important modulators of HCV-associated diseases. The viral aspects that influence HCV infection are presented, followed by a discussion about evolutionary aspects of host and HCV interaction. HCV and HIV infections are close related. Thus, we also present a discussion about HIV/HCV co-infection, focusing on cellular and molecular aspects of this interaction. Pharmacogenetics and treatment of HCV infection are the last topics of this review. The understanding of how the host genetics interacts with viral and environmental factors is crucial for the development of new strategies to prevent HCV infection, even in an era of potential development of pan-genotypic antivirals.

Glucose Metabolism in T Cells and Monocytes: New Perspectives in HIV Pathogenesis

Activation of the immune system occurs in response to the recognition of foreign antigens and receipt of optimal stimulatory signals by immune cells, a process that requires energy. Energy is also needed to support cellular growth, differentiation, proliferation, and effector functions of immune cells. In HIV-infected individuals, persistent viral replication, together with inflammatory stimuli contributes to chronic immune activation and oxidative stress. These conditions remain even in subjects with sustained virologic suppression on antiretroviral therapy. Here we highlight recent studies demonstrating the importance of metabolic pathways, particularly those involving glucose metabolism, in differentiation and maintenance of the activation states of T cells and monocytes. We also discuss how changes in the metabolic status of these cells may contribute to ongoing immune activation and inflammation in HIV- infected persons and how this may contribute to disease progression, establishment and persistence of the HIV reservoir, and the development of co-morbidities. We provide evidence that other viruses such as Epstein-Barr and Flu virus also disrupt the metabolic machinery of their host cells. Finally, we discuss how redox signaling mediated by oxidative stress may regulate metabolic responses in T cells and monocytes during HIV infection.

Liver Damage in Patients with HCV/HIV Coinfection Is Linked to HIV-Related Oxidative Stress

HIV infection aggravates the progression of liver damage in HCV-coinfected patients, with the underlying pathogenesis being multifactorial. Although high level of oxidative stress has been observed frequently in patients infected with HIV or HCV, the status of oxidative stress in HIV/HCV coinfection and its contribution to HCV liver damage have not been determined. This study involved 363 HBsAg-negative, anti-HCV-positive former blood donors recruited from a village in central China in July 2005; of these, 140 were positive for HIV. Of these 363 subjects, 282 were successfully followed up through July 2009. HIV/HCV-coinfected subjects had higher rates of end-stage liver disease-related death than those monoinfected with HCV. Liver ultrasound manifestations were poor in HIV-positive than in HIV-negative individuals, in both chronic HCV carriers and those with resolved HCV. Serum concentrations of total glutathione (tGSH), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), GSSG, and reduced GSH were higher in HIV-positive than HIV-negative subjects. GSSG concentrations were higher in HIV-infected subjects with abnormal ALT/AST levels than in those with normal ALT/AST levels and were associated with poorer liver ultrasound manifestations. These finding indicated that HIV infection accelerated HCV-associated liver damage in HIV/HCV-coinfected individuals. Increased oxidative stress, induced primarily by HIV coinfection, may contribute to aggravated liver damage.

Alcohol and HIV: Experimental and Clinical Evidence of Combined Impact on the Lung

Despite antiretroviral therapy, lung disease is a leading cause of death in individuals infected with human immunodeficiency virus type 1 (HIV). Individuals infected with HIV are susceptible to serious bacterial and viral infections, such as pneumococcus and influenza, which are particularly problematic for lung health, resulting in lung injury. Additionally, HIV-infected individuals are susceptible to a number of pulmonary diseases for unknown reasons. Alcohol, the most commonly abused drug in the world, continues to exact an enormous toll on morbidity and mortality in individuals living with HIV. Chronic alcohol abuse has been shown to affect lung immunity, resulting in significant lung injury. There is a paucity of literature on the additive effects of HIV and alcohol, two diseases of immune senescence, in the lung. This chapter begins by discussing the latest literature evaluating the epidemiology of HIV, alcohol use, and lung health focusing on two prevalent infections, tuberculosis and pneumococcal pneumonia. In parallel, we discuss the interactions of alcohol and HIV on the risk for acute lung injury and subsequent morbidity and mortality. We then discuss the pathophysiology of how these two diseases of immune dysfunction affect the lung, with a focus on the oxidative stress, alveolar macrophage host immune capacity, and immunomodulatory role of zinc in the airway. Finally, we review the latest literature on how HIV and alcohol affect other pulmonary disorders including chronic obstructive pulmonary disease, pulmonary hypertension, and lung cancer.

New targets and inhibitors of mycobacterial sulfur metabolism

The identification of new antibacterial targets is urgently needed to address multidrug resistant and latent tuberculosis infection. Sulfur metabolic pathways are essential for survival and the expression of virulence in many pathogenic bacteria, including Mycobacterium tuberculosis. In addition, microbial sulfur metabolic pathways are largely absent in humans and therefore, represent unique targets for therapeutic intervention. In this review, we summarize our current understanding of the enzymes associated with the production of sulfated and reduced sulfur-containing metabolites in Mycobacteria. Small molecule inhibitors of these catalysts represent valuable chemical tools that can be used to investigate the role of sulfur metabolism throughout the Mycobacterial lifecycle and may also represent new leads for drug development. In this light, we also summarize recent progress made in the development of inhibitors of sulfur metabolism enzymes.

Iron status in HIV-1 infection: implications in disease pathology

BACKGROUND

There had been conflicting reports with levels of markers of iron metabolism in HIV infection. This study was therefore aimed at investigating iron status and its possible mediation of severity of HIV- 1 infection and pathogenesis.

METHOD

Eighty (80) anti-retroviral naive HIV-1 positive and 50 sero-negative controls were recruited for the study. Concentrations of serum total iron, transferrin, total iron binding capacity (TIBC), CD4+ T -lymphocytes, vitamin C, zinc, selenium and transferrin saturation were estimated.

RESULTS

The mean CD4+ T-lymphocyte cell counts, serum iron, TIBC, transferrin saturation for the tests and controls were 319 ± 22, 952 ± 57 cells/μl (P < 0.001), 35 ± 0.8, 11.8 ± 0.9 μmol/l (P < 0.001), 58.5 ± 2.2, 45.2 ± 2.4 μmol/l (P < 0.005) and 68.8 ± 3.3, 27.7 ± 2.2%, (P <0.001), respectively, while mean concentrations of vitamin C, zinc and selenium were 0.03 ± 0.01, 0.3 ± 0.04 (P < 0.001), 0.6 ± 0.05, 11.9 ± 0.26 μmol/l (P < 0.001) and 0.1 ± 0.01, 1.2 ± 0.12 μmol/l (P < 0.001) respectively. Furthermore, CD4+ T-lymphocyte cell count had a positive correlation with levels of vitamin C (r = 0.497, P < 0.001), zinc (r = 0.737, P < 0.001), selenium (r = 0.639, P < 0.001) and a negative correlation with serum iron levels (r = -0.572, P < 0.001).

CONCLUSION

It could be inferred that derangement in iron metabolism, in addition to oxidative stress, might have contributed to the depletion of CD4+ T cell population in our subjects and this may result in poor prognosis of the disease.

Relationship of Oxidative Stress with HIV Disease Progression in HIV/HCV Co-infected and HIV Mono-infected Adults in Miami

BACKGROUND

HIV and HCV infections are both characterized by increased oxidative stress. Information on the magnitude of this increase and its consequences in HIV/HCV co-infection and viral replication is limited. We investigated the relationship between oxidative stress and HIV-progression in HIV/HCV co-infected and HIV mono-infected adults.

METHODS

106 HIV/HCV co-infected and 115 HIV mono-infected participants provided demographic information and blood to determine 8-oxo-dG and percent oxidized glutathione.

RESULTS

HIV/HCV co-infected subjects had higher percent oxidized glutathione, higher HIV viral load, lower mtDNA copies and higher liver fibrosis than mono-infected subjects. In a small sample of HIV/HCV co-infected participants with liver biopsy, 8-oxo-dG was significantly lower in participants with low fibrosis scores than those with high fibrosis scores, and the grade of inflammation was strongly associated with oxidized glutathione.

CONCLUSIONS

HIV/HCV co-infection seems to diminish the capacity of the antioxidant system to control oxidative stress, and increases HIV replication.

A review of the evidence concerning hepatic glutathione depletion and susceptibility to hepatotoxicity after paracetamol overdose

Paracetamol (acetaminophen) poisoning is common throughout the world. The management of nonstaggered (acute) paracetamol overdose is based on the plasma paracetamol concentration plotted on a treatment nomogram. In the UK there are two treatment lines on this nomogram, with the lower treatment line used for individuals felt to be at ‘high risk’ of paracetamol-related hepatotoxicity either as a result of induction of cytochrome P450 isoenzymes or reduction of intrahepatic glutathione. In this article we review the risk factors that, in current guidelines, are felt to increase risk due to a reduction in intrahepatic glutathione concentrations. Based on our review of the published literature, we feel that cystic fibrosis, acute viral illness, malnutrition, and eating disorders such as anorexia nervosa are likely to be associated with reduction in intrahepatic glutathione concentrations, and that this risk is likely to be related to malnutrition secondary to the disease. Chronic hepatitis C infection is also associated with reduced glutathione concentrations, although this appears to be independent of any associated malnutrition. Ageing and acute fasting are not associated with an increased risk of paracetamol-related hepatotoxicity due to reductions in glutathione concentrations. Finally, the evidence for HIV infection is inconclusive, particularly as the majority of studies were conducted in the pre-anti-viral treatment (HAART) era; however it is likely that patients with symptomatic HIV/AIDS have reduced glutathione concentrations due to associated malnutrition. Although there have been few studies which have specifically investigated whether there is an association between reduced intrahepatic glutathione concentrations and increased risk of paracetamol-related hepatotoxicity, in our opinion, it is likely that the above conditions that are associated with reduced glutathione concentrations, will be associated with an increased risk of paracetamol-related hepatotoxicity.

Expression of the whey acidic protein (Wap) is necessary for adequate nourishment of the offspring but not functional differentiation of mammary epithelial cells

Whey acidic protein (WAP) is the principal whey protein found in rodent milk, which contains a cysteine-rich motif identified in some protease inhibitors and proteins involved in tissue modeling. The expression of the Wap gene, which is principally restricted to the mammary gland, increases more than 1,000-fold around mid-pregnancy. To determine whether the expression of this major milk protein gene is a prerequisite for functional differentiation of mammary epithelial cells, we generated conventional knockout mice lacking two alleles of the Wap gene. Wap-deficient females gave birth to normal litter sizes and, initially, produced enough milk to sustain the offspring. The histological analysis of postpartum mammary glands from knockout dams does not reveal striking phenotypic abnormalities. This suggests that the expression of the Wap gene is not required for alveolar specification and functional differentiation. In addition, we found that Wap is dispensable as a protease inhibitor to maintain the stability of secretory proteins in the milk. Nevertheless, a significant number of litters thrived poorly on Wap-deficient dams, in particular during the second half of lactation. This observation suggests that Wap may be essential for the adequate nourishment of the growing young, which triple in size within the first 10 days of lactation. Important implications of these findings for the use of Wap as a marker for advanced differentiation of mammary epithelial cells and the biology of pluripotent progenitors are discussed in the final section.

Molecular mechanisms and potential clinical significance of S-glutathionylation

Protein S-glutathionylation, the reversible binding of glutathione to protein thiols (PSH), is involved in protein redox regulation, storage of glutathione, and protection of PSH from irreversible oxidation. S-Glutathionylated protein (PSSG) can result from thiol/disulfide exchange between PSH and GSSG or PSSG; direct interaction between partially oxidized PSH and GSH; reactions between PSH and S-nitrosothiols, oxidized forms of GSH, or glutathione thiyl radical. Indeed, thiol/disulfide exchange is an unlikely intracellular mechanism for S-glutathionylation, because of the redox potential of most Cys residues and the GSSG export by most cells as a protective mechanism against oxidative stress. S-Glutathionylation can be reversed, following restoration of a reducing GSH/GSSG ratio, in an enzyme-dependent or -independent manner. Currently, definite evidence of protein S-glutathionylation has been clearly demonstrated in few human diseases. In aging human lenses, protein S-glutathionylation increases; during cataractogenesis, some of lens proteins, including alpha- and beta-crystallins, form both mixed disulfides and disulfide-cross-linked aggregates, which increase with cataract severity. The correlation of lens nuclear color and opalescence intensity with protein S-glutathionylation indicates that protein-thiol mixed disulfides may play an important role in cataractogenesis and development of brunescence in human lenses. Recently, specific PSSG have been identified in the inferior parietal lobule in Alzheimer's disease. However, much investigation is needed to clarify the actual involvement of protein S-glutathionylation in many human diseases.

Analysis of the thiol status of peripheral blood leukocytes in rheumatoid arthritis patients

Although the exact etiology of rheumatoid arthritis (RA) remains unknown, there is increasing evidence that reactive oxygen species and a pro-oxidant/antioxidant imbalance are an important part of the pathogenesis of joint tissue injury. Flow cytometry was used to evaluate the thiol status [surface-thiols and intracellular glutathione (iGSH)] of leukocytes from RA patients and controls. Levels of surface-thiols and iGSH of leukocytes from RA patients were significantly lower than of leukocytes from controls. CD53, a glycoprotein of the tetraspanin superfamily, which coprecipitates with the GSH recycling enzyme gamma-glutamyl transpeptidase, was elevated significantly on leukocytes from RA patients compared with leukocytes from controls. Surface-thiols and GSH play important roles in redox buffering of cells, providing protection from oxidative stress. The chronic inflammation of RA has been associated with oxidative stress, which is shown to cause a decline in the levels of cellular antioxidant sulfhydryls (R-SH). As antioxidant-protective levels also decline with age, the problem is compounded in older RA patients, who did have fewer R-SH. Chronic stress can also have an effect on telomere lengths, determining cell senescence and longevity. Although telomeres shorten with increasing age, our flow cytometry studies indicate that accelerated shortening in telomere lengths occurs with increasing age of RA patients, suggesting premature cellular aging. The paradox is that lymphocytes from RA patients are believed to resist apoptosis, and we suggest that the elevated expression of CD53, which results from the increased oxidative stress, may protect against apoptosis.

Increased adverse drug reactions to antimicrobials and anticonvulsants in patients with HIV infection

OBJECTIVE

To review the incidence, signs, symptoms, and mechanisms of adverse drug reactions (ADRs) to sulfonamides, anticonvulsants, and antimycobacterial medications among people with HIV.

DATA SOURCES

Searches of MEDLINE/PubMed (1980-November 2005) and National Library of Medicine Meeting Abstracts (1989-November 2005), as well as hand searches of journals and abstracts, were conducted to identify primary literature. Reference lists were reviewed to identify additional relevant reports.

STUDY SELECTION AND DATA EXTRACTION

Relevant articles and abstracts, particularly of in vitro experiments and clinical studies, were compiled and reviewed.

DATA SYNTHESIS

ADRs, especially in HIV-infected patients, are a cause for concern. Sulfonamides, anticonvulsants, and antimycobacterial drugs are commonly used to prevent and treat complications of HIV, including seizures and opportunistic infections. Patients with HIV have a much greater rate of ADRs to these drug classes, including severe and life-threatening hypersensitivity reactions. Several mechanisms of these ADRs have been postulated. Sulfamethoxazole and anticonvulsant hypersensitivity may involve the increased formation and decreased detoxification of reactive metabolites. The mechanisms for the marked increase in hypersensitivity ADRs to antimycobacterial drugs may be related to an altered immune profile in patients infected with both tuberculosis and HIV.

CONCLUSIONS

ADRs to antimicrobial and anticonvulsant therapy cause markedly increased morbidity and mortality in HIV-positive patients. Further research involving the interaction between HIV and the increased ADRs to these drugs is required.

Retrovirus-induced oxidative stress with neuroimmunodegeneration is suppressed by antioxidant treatment with a refined monosodium alpha-luminol (Galavit)

Oxidative stress is involved in many human neuroimmunodegenerative diseases, including human immunodeficiency virus disease/AIDS. The retrovirus ts1, a mutant of Moloney murine leukemia virus, causes oxidative stress and progressive neuro- and immunopathology in mice infected soon after birth. These pathological changes include spongiform neurodegeneration, astrogliosis, thymic atrophy, and T-cell depletion. Astrocytes and thymocytes are directly infected and killed by ts1. Neurons are not infected, but they also die, most likely as an indirect result of local glial infection. Cytopathic effects of ts1 infection in cultured astrocytes are associated with accumulation of the viral envelope precursor protein gPr80env in the endoplasmic reticulum (ER), which triggers ER stress and oxidative stress. We have reported (i) that activation of the Nrf2 transcription factor and upregulation of antioxidative defenses occurs in astrocytes infected with ts1 in vitro and (ii) that some ts1-infected astrocytes survive infection by mobilization of these pathways. Here, we show that treatment with a refined monosodium alpha-luminol (Galavit; GVT) suppresses oxidative stress and Nrf2 activation in cultured ts1-infected astrocytes. GVT treatment also inhibits the development of spongiform encephalopathy and gliosis in the central nervous system (CNS) in ts1-infected mice, preserves normal cytoarchitecture in the thymus, and delays paralysis, thymic atrophy, wasting, and death. GVT treatment of infected mice reduces ts1-induced oxidative stress, cell death, and pathogenesis in both the CNS and thymus of treated animals. These studies suggest that oxidative stress mediates ts1-induced neurodegeneration and T-cell loss.

Role of Lymphocyte Multidrug Resistance Protein 1 in HIV Infection

The multidrug resistance protein 1 (MRP1) is a drug transporter that protects cells from oxidative stress, which increases HIV-1 replication. The aim of this study was to characterize the expression, function, and role of lymphocyte MRP1 in HIV-1 infection and its modulation by antiretroviral drugs such as the protease inhibitors (PIs). Peripheral blood mononuclear cells (PBMCs) from HIV-positive individuals do not show significant alterations of MRP1 expression despite highly active antiretroviral therapy and HIV plasma viral load levels; however, they exhibit different intracellular MRP1 expression as compared with healthy subjects. By contrast, MRP efflux function is increased in subjects with primary HIV infection and becomes defective in later stages of the infection. PI- and probenecid (PBCD)-mediated inhibition of MRP lowers the in vitro stress-induced response of lymphoid cells by reducing the level of the specific reactive oxygen species superoxide anion and hydrogen peroxide. Finally, the blockade of MRP by PBCD and PIs down-modulates HIV-1 replication by a mechanism independent of inhibition of the HIV-1 protease. Our results are consistent with a model wherein HIV replication is favored by the MRP1-related oxidative stress and inhibition of MRP1 may contribute to the antiviral activity of PIs.

The role of phase II antioxidant enzymes in protecting memory T cells from spontaneous apoptosis in young and old mice

Aging is associated with a functional decline and change in the phenotypic distribution of T cell subsets. The free radical theory of aging is widely promoted as the mechanistic basis for cellular senescence, including the immune system. Although the exact molecular explanation for the role of oxidative stress in cellular senescence is unclear, there is a connection to altered mitochondrial function, both as a contributor and as a target of oxidative stress. In this study we demonstrate that splenic T lymphocytes from old C57BL/6 mice exhibit a significant decline in mitochondrial membrane potential (deltapsi(m)). However, despite this change, there is a lower rate of withdrawal apoptosis in the memory CD4+ and CD8+ T cells. To explain the survival of these long-lived cells against a background of increased oxidative stress, we demonstrate increased glutathione production and phase II enzyme expression, which combine to protect memory T cells against oxidative stress, mitochondrial dysfunction, and cell death. The accumulation of memory T cells with aging explains higher phase II enzyme expression in CD4+ and CD8+ T cells from old mice. Compared with wild-type mice, mice lacking the expression of NF-E2-related factor-2, the transcription factor that regulates phase II enzyme expression, had a significantly enhanced rate of apoptosis in the presence of an oxidative stress stimulus. NF-E2-related factor-2-deficient T cells exhibit a bigger decline in deltapsi(m) and increased reactive oxygen species production than cells from wild-type animals. Taken together, we suggest that phase II enzyme expression and the accompanying increase in intracellular thiol levels protect memory T cells from mitochondrial dysfunction and spontaneous apoptosis.

Evaluation of antioxidant effect of Semecarpus anacardium Linn. nut extract on the components of immune system in adjuvant arthritis

The effect of Semecarpus anacardium Linn. nut extract (SA) on the level of Lipid peroxides (LPO) and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) in the lymphocytes and lymphoid organs, namely spleen and thymus of adjuvant induced arthritic rats, were investigated. The results were compared with normal and untreated arthritic rats. The levels of reactive oxygen species (ROS), namely Hydroxy radical, Superoxide radical, and H2O2 were also measured in spleen, thymus, and lymphocytes of control and experimental animals. Biochemical markers of inflammation namely C-reactive protein (CRP) level and Erythrocyte sedimentation rate (ESR) were determined. Anti-arthritic profile was evaluated from the changes in the paw edema and arthritic scores of arthritic and drug-treated rats. A significant increase in the level of LPO, ROS and decreased levels of antioxidant enzymes in arthritic rats were observed. On treatment with the drug, the above changes were reverted back to near normal levels. The increment in CRP level and ESR observed in arthritic animals were found to be significantly restored in SA treated rats. There were no significant changes in sole drug-administered normal rats. Semecarpus anacardium Linn. nut extract significantly decreased the paw edema and arthritic score in arthritic rats on administration, whereas in untreated arthritic rats, there was a significant edema in the hind paw.

Impaired base excision repair and accumulation of oxidative base lesions in CD4+ T cells of HIV-infected patients

Several studies have reported enhanced oxidative stress in patients with HIV infection. An important pathophysiologic consequence of increased oxidative stress is endogenous DNA damage, and the base excision repair pathway is the most important mechanism to withstand such deleterious effects. To investigate the role of base excision repair in HIV infection, we examined 7,8-dihydro-8-oxoguanine (8-oxoG) levels as a marker of oxidative DNA damage and DNA glycosylase activities in CD4(+) and CD8(+) T cells of HIV-infected patients and controls. These results showed that the HIV-infected patients, particularly those with advanced disease, had increased levels of 8-oxoG in CD4(+) T cells and marked declines in DNA glycosylase activity for the repair of oxidative base lesions in these cells. In contrast, CD8(+) T cells from HIV-infected patients, with 8-oxoG levels similar to those in healthy controls, showed enhanced capacity to repair oxidative DNA damage. Finally, highly active antiretroviral therapy induced increased glycosylase activity in CD4(+) T cells and normalized 8-oxoG levels. This imbalance between the accumulation of oxidative DNA damage and the capacity to repair such lesions in CD4(+) T cells may represent a previously unrecognized mechanism involved in the numerical and functional impairment of CD4(+) T cells in patients with HIV infection.

The extracellular microenvironment plays a key role in regulating the redox status of cell surface proteins in HIV-infected subjects

There is an overwhelming interest in the study of the redox status of the cell surface affecting redox signaling in the cells and also predicting the total redox status of the cells. Measuring the total surface thiols (cell surface molecule thiols, csm-SH) we have shown that the overall level of surface thiols is tightly controlled. In vitro, the total concentration of intracellular glutathione (iGSH) seems to play a regulatory role in determination of the amounts of reduced proteins on cells. In addition, short term exposure of the cell surface to glutathione disulfide (GSSG, oxidized GSH) seems to reduce the overall levels of csm-SH suggesting that the function of some cysteine containing proteins on the cell surface may be regulated by the amount of GSSG secreted from the cells or the GSSG available in the extracellular environment. Examination of peripheral blood mononuclear cells (PBMCs) from healthy or HIV-infected subjects failed to reveal a similar correlation between the intra- and extracellular thiol status of cells. Although there is a relatively wide variation between individuals in both csm-SH and iGSH there is no correlation between the iGSH and csm-SH levels measured for healthy and HIV-infected individuals. There are many reports suggesting different redox active proteins on the cell surface to be the key players in the total cell surface redox regulation. However, we suggest that the redox status of the cells is regulated through a complex and tightly regulated mechanism that needs further investigation. In the mean time, overall surface thiol measurements together with case specific protein determinations may offer the most informative approach. In this review, we discuss our own results as well as results from other laboratories to argue that the overall levels of surface thiols on the exofacial membrane are regulated primarily by redox status of the cell surface microenvironment.

Neopterin in HIV-1 infection

Neopterin is well established as a reliable marker in HIV-1 infection. Neopterin concentrations measured in urine or serum indicate sensitively the course and progression of the disease as well as efficacy of anti-retroviral therapy. The main trigger for neopterin production is Th1-type cytokine interferon-gamma. During acute HIV-1 infection, enhanced formation of neopterin occurs already at a very early time point, before antibody seroconversion takes place. After this stage, neopterin concentrations in serum and urine closely correlate with virus load in the circulation of HIV-1-infected patients. Data provide evidence for an important role of immune activation and Th1-type cytokine interferon-gamma in the pathogenesis of HIV-1 infection. This review subsumes the importance of neopterin as a marker in HIV-1 infection. Further evidence is increasing, that neopterin derivatives might modulate immune response by interfering with the cellular redox balance, activating redox-sensitive transcription factors, or inducing apoptosis in specific cell types. The possible impact of neopterin derivatives and of other biochemical pathways induced by interferon-gamma such as indoleamine 2,3-dioxygenase in chronic diseases like HIV-1 infection is discussed.

Lymphocyte surface thiol levels

Recent studies have implicated reduced thiols (cysteine -SH) in the function of individual cell surface proteins. Studies presented here demonstrate that the overall level of reduced thiols on cell surface molecules differs on individual subsets of peripheral blood mononuclear cells and that these levels can be manipulated in vitro by altering the level of intracellular glutathione (iGSH). To quantitate cell surface thiols, we have developed a Hi-D (11-color) fluorescence-activated cell sorter method in which we covalently couple a fluorescent molecule, Alexa-maleimide, to free (reduced) -SH groups on proteins or other molecules exposed on the cell surface (exofacial membrane). In addition, to reveal changes in cell surface thiol levels in response to various in vitro treatments, we used a pair of fluorescent Alexa dyes with distinct excitation and emission spectra to stain the cells before and after treatments. These in vitro studies demonstrate that decreasing iGSH, by specifically inhibiting its synthesis, decreases cell surface molecule thiols (csm-SH) and that preventing loss of iGSH also prevents loss of csm-SH. However, examination of peripheral blood mononuclear cell subsets tested immediately after isolation from healthy or HIV-infected subjects failed to reveal a similar relationship between internal iGSH and csm-SH. Although there is a relatively wide variation between individuals in both csm-SH and iGSH, there is no correlation between median iGSH and csm-SH compared for 22 healthy and 36 HIV-infected subjects. Collectively, our findings indicate that local environment plays a greater role in determining the redox status of cell surface molecules than the internal redox status of the cells.

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.

The effect of N-acetylcysteine supplementation upon viral load, CD4, CD8, total lymphocyte count and hematocrit in individuals undergoing antiretroviral treatment

Individuals infected with the human immunodeficiency virus (HIV-1) present with decreased CD4, a progressive increase in viral load, compromised cell immune defense, and hematologic alterations. The aim of this study was to assess the serum viral load, CD4, CD8, lymphocyte count and hematocrit at the beginning of antiretroviral therapy in individuals who were supplemented with N-acetylcysteine (NAC). Twenty volunteers participated in this double-blind, placebo-controlled 180-day study. Ten participants received 600 mg of NAC per day (NAC group) and the other ten serving as a control group received placebo. The above mentioned parameters were determined before treatment, and after 60, 120 and 180 days. In NAC-treated patients hematocrit remained stable and an increase in CD4 cell count took place earlier than that in the control group.

Protein glutathionylation: coupling and uncoupling of glutathione to protein thiol groups in lymphocytes under oxidative stress and HIV infection

We show here that exposure to oxidative stress induces glutathione (GSH) modification of protein cysteinyl residues (glutathionylation) in T cell blasts. Treating the cells with the oxidant diamide induces thiolation of a series of proteins that can be detected by 2D electrophoresis when 35S-cysteine is used to label the intracellular GSH pool. This thiolation is reversible, proteins are rapidly dethiolated and GSH is released from proteins once the oxidants are washed and the cells are allowed to recover. Dethiolation is dependent on the availability of GSH and thiols, since it is inhibited by GSH-depleting agents and improved by N-acetyl-L-cysteine (NAC). The capacity of these agents to reverse glutathionylation is diminished in T cell blasts infected in vitro with HIV, which is known to cause oxidative stress. Consistent with these findings, the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), an enzyme known to be inhibited by glutathionylation, is inhibited in diamide-treated cells and recovers rapidly when cells are allowed to dethiolate. Further, GAPDH activity is diminished by GSH-depleting agents and augmented by NAC. Thus, reversible glutathionylation of proteins can rapidly shift the activity of a key metabolic enzyme and thereby result in dramatic, reversible changes in cellular metabolism.

Free radicals in the physiological control of cell function

At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, however, nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. Many of the ROS-mediated responses actually protect the cells against oxidative stress and reestablish "redox homeostasis." Higher organisms, however, have evolved the use of NO and ROS also as signaling molecules for other physiological functions. These include regulation of vascular tone, monitoring of oxygen tension in the control of ventilation and erythropoietin production, and signal transduction from membrane receptors in various physiological processes. NO and ROS are typically generated in these cases by tightly regulated enzymes such as NO synthase (NOS) and NAD(P)H oxidase isoforms, respectively. In a given signaling protein, oxidative attack induces either a loss of function, a gain of function, or a switch to a different function. Excessive amounts of ROS may arise either from excessive stimulation of NAD(P)H oxidases or from less well-regulated sources such as the mitochondrial electron-transport chain. In mitochondria, ROS are generated as undesirable side products of the oxidative energy metabolism. An excessive and/or sustained increase in ROS production has been implicated in the pathogenesis of cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and other diseases. In addition, free radicals have been implicated in the mechanism of senescence. That the process of aging may result, at least in part, from radical-mediated oxidative damage was proposed more than 40 years ago by Harman (J Gerontol 11: 298-300, 1956). There is growing evidence that aging involves, in addition, progressive changes in free radical-mediated regulatory processes that result in altered gene expression.

Erythrocytic glutathione and plasma cysteine status of human immunodeficient patients

Both deficient and normal blood levels of glutathione (GSH) and cysteine (Cys) have been reported in HIV patients, a discrepancy that has been attributed to different methodologies. The goal of this study was to apply our analytical method to this problem. Blood samples from HIV patients and healthy subjects were collected, immediately stabilized, and quantified using high performance liquid chromatography with dual electrochemical detection. The results showed that the erythrocytic GSH levels were the same in healthy subjects and in HIV patients regardless of their CD4 lymphocyte level. Only those with the lowest CD4 level plus opportunistic infections had supranormal [corrected] GSH concentrations (P < 0.001). GSH plus glutathione disulfide (GSSG) levels also were normal in patients. However, the Cys contents were higher in patients than in controls (P < 0.05). These findings demonstrated that HIV patients have normal erythrocytic GSH concentrations and supranormal Cys levels.

Rethinking cystic fibrosis pathology: the critical role of abnormal reduced glutathione (GSH) transport caused by CFTR mutation

Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed.

Current status of flow cytometry in cell and molecular biology

This review summarizes recent developments in flow cytometry (FC). It gives an overview of techniques currently available, in terms of apparatus and sample handling, a guide to evaluating applications, an overview of dyes and staining methods, an introduction to internet resources, and a broad listing of classic references and reviews in various fields of interest, as well as some recent interesting articles.

LAT, the linker for activation of T cells: a bridge between T cell-specific and general signaling pathways

A key event in the regulation of the adaptive immune response is the binding of major histocompatibility complex-bound foreign peptides to T cell antigen receptors (TCRs) that are present on the cell surface of T lymphocytes. Recognition of the presence of cognate antigen in the host animal induces a series of biochemical changes within the T cell; these changes, in the context of additional signals from other surface receptors, ultimately result in massive proliferation of receptor-engaged T cells and the acquisition of effector and memory functions. Early studies established the importance of the activation of the enzymes phospholipase C-gamma1 (PLC-gamma1) and phosphatidylinositol 3-kinase (PI3K), as well as the small molecular weight heterotrimeric guanine nucleotide binding protein (G protein) Ras, in this process. These biochemical events are dependent on the activity of several protein tyrosine kinases that become activated immediately upon TCR engagement. An unresolved question in the field has been which molecules and what sequence of events tie together the early tyrosine phosphorylation events with the activation of these downstream signaling molecules. A likely candidate for linking the proximal and distal portions of the TCR signaling pathway is the recently described protein, LAT. LAT is a 36-kD transmembrane protein that becomes rapidly tyrosine-phosphorylated after TCR engagement. Phosphorylation of LAT creates binding sites for the Src homology 2 (SH2) domains of other proteins, including PLC-gamma1, Grb2, Gads, Grap, 3BP2, and Shb, and indirectly binds SOS, c-Cbl, Vav, SLP-76, and Itk. LAT is localized to the glycolipid-enriched membrane (GEM) subdomains of the plasma membrane by virtue of palmitoylation of two cysteine residues positioned near the endofacial side of the plasma membrane. Notably, in the absence of LAT, TCR engagement does not lead to activation of distal signaling events. This review examines the circumstances surrounding the discovery of LAT and our current understanding of its properties, and discusses current models for how LAT may be functioning to support the transduction of TCR-initiated, T cell-specific signaling events to the distal, general signaling machinery.

Glutathione and immune function

The immune system works best if the lymphoid cells have a delicately balanced intermediate level of glutathione. Even moderate changes in the intracellular glutathione level have profound effects on lymphocyte functions. Certain functions, such as the DNA synthetic response, are exquisitely sensitive to reactive oxygen intermediates and, therefore, are favoured by high levels of the antioxidant glutathione. Certain signal pathways, in contrast, are enhanced by oxidative conditions and favoured by low intracellular glutathione levels. The available evidence suggests that the lymphocytes from healthy human subjects have, on average, an optimal glutathione level. There is no indication that immunological functions such as resistance to infection or the response to vaccination may be enhanced in healthy human subjects by administration of glutathione or its precursor amino acid cysteine. However, immunological functions in diseases that are associated with a cysteine and glutathione deficiency may be significantly enhanced and potentially restored by cysteine supplementation. This factor has been studied most extensively in the case of human immunodeficiency virus (HIV)-infected patients who were found to experience, on average, a massive loss of S equivalent to a net loss of approximately 4 g cysteine/d. Two randomized placebo-controlled trials have shown that treatment of HIV-infected patients with N-acetyl-cysteine caused in both cases a significant increase in all immunological functions under test, including an almost complete restoration of natural killer cell activity. It remains to be tested whether cysteine supplementation may be useful also in other diseases and conditions that are associated with a low mean plasma cystine level and impaired immunological functions.

N-acetylcysteine replenishes glutathione in HIV infection

BACKGROUND

Glutathione (GSH) deficiency is common in HIV-infected individuals and is associated with impaired T cell function and impaired survival. N-acetylcysteine (NAC) is used to replenish GSH that has been depleted by acetaminophen overdose. Studies here test oral administration of NAC for safe and effective GSH replenishment in HIV infection.

DESIGN

Oral NAC administration in a randomized, 8-week double-blind, placebo-controlled trial followed by optional open-label drug for up to 24 weeks.

SUBJECTS

HIV-infected, low GSH, CD4 T cells < 500 micro L(-1), no active opportunistic infections or other debilitation; n = 81. Study conducted prior to introduction of protease inhibitors.

RESULTS

Whole blood GSH levels in NAC arm subjects significantly increased from 0.88 mM to 0.98 mM, bringing GSH levels in NAC-treated subjects to 89% of uninfected controls (P = 0.03). Baseline GSH levels in the placebo group (0.91) remained essentially the same during the 8 week placebo-controlled trial. T cell GSH, adjusted for CD4 T cell count and beta2-microglobulin levels, also increased in the NAC-treated subjects (P = 0.04). Adverse effects were minimal and not significantly associated with NAC ingestion.

CONCLUSION

NAC treatment for 8 weeks safely replenishes whole blood GSH and T cell GSH in HIV-infected individuals. Thus, NAC offers useful adjunct therapy to increase protection against oxidative stress, improve immune system function and increase detoxification of acetaminophen and other drugs. These findings suggest that NAC therapy could be valuable in other clinical situations in which GSH deficiency or oxidative stress plays a role in disease pathology, e.g. rheumatoid arthritis, Parkinson's disease, hepatitis, liver cirrhosis, septic shock and diabetes.

Oxidative stress in HIV-1-infected injection drug users

Low serum antioxidant levels observed in many HIV-infected populations could be largely due to an increase in oxidative stress (defined as a disturbance in the equilibrium status of prooxidant/antioxidant systems of intact cells). In HIV infection, oxidative stress may be caused by both overproduction of reactive oxygen intermediates (ROIs) and a simultaneous deficiency of antioxidant defenses. Furthermore, injection drug use has been associated with increased levels of oxidative stress in animal models. Currently, there is widespread use of self-prescribed antioxidant supplementation among the HIV-infected population and a prevailing belief that high-dose supplementation is beneficial, or at the very least, not harmful. Data from our studies show that HIV-positive injection drug users (IDUs) who are on antiretroviral combination therapies including a protease inhibitor have significantly higher mean serum levels of several antioxidants, independent of dietary and supplemental intake, compared with both HIV-negative IDUs and HIV-positive IDUs not taking protease inhibitors. This suggests that oxidative stress may be reduced in patients taking protease inhibitors. Preliminary data suggest that the future of antioxidant supplementation therapy, if any, will be one in which different doses of supplements are recommended for HIV-infected patients on the various antiretroviral treatment regimens. More research is needed to determine the interactions among injection drug use, oxidative stress, antiretroviral therapy, and the use of antioxidant supplements in HIV infection. Until more is known, caution should be exercised when using or recommending high-dose antioxidant supplementation in HIV-infected individuals, particularly in those on protease inhibitors, since moderate levels of oxidative stress are involved in a number of useful physiologic processes.

Virological and immunological effects of antioxidant treatment in patients with HIV infection

BACKGROUND

Intracellular oxidative stress in CD4+ lymphocytes due to disturbed glutathione homeostasis may lead to impaired lymphocyte functions and enhanced HIV replication in patients with HIV infection, especially in those with advanced immunodeficiency. The aim of the present study was to assess whether short-term, high-dose antioxidant treatment might have effects on immunological and virological parameters in patients with HIV infection.

MATERIALS AND METHODS

In this pilot study, we examined virological and immunological effects of antioxidant combination treatment for 6 days with high doses of N-acetylcysteine (NAC) and vitamin C in 8 patients with HIV infection. The following were assayed before, during and after antioxidant treatment: HIV RNA plasma levels; numbers of CD4+, CD8+, and CD14+ leukocytes in blood; plasma thiols; intracellular glutathione redox status in CD4+ lymphocytes and CD14+ monocytes; lymphocyte proliferation; lymphocyte apoptosis and plasma levels of tumour necrosis factor (TNF)alpha; soluble TNF receptors and neopterin in plasma.

RESULTS

No significant changes in HIV RNA plasma levels or CD4+ lymphocyte counts in blood were noted during antioxidant treatment in the patient group. However, in the 5 patients with the most advanced immunodeficiency (CD4+ lymphocyte counts < 200 x 106 L(-1)), a significant rise in CD4+ lymphocyte count, a reduction in HIV RNA plasma level of 0.8 log, an enhanced lymphocyte proliferation and an increased level of intracellular glutathione in CD4+ lymphocytes were found. No change in lymphocyte apoptosis was noted.

CONCLUSIONS

Short-term, high-dose combination treatment with NAC and vitamin C in patients with HIV infection and advanced immunodeficiency lead to immunological and virological effects that might be of therapeutic value.

Thiol homeostasis and supplements in physical exercise

Thiols are a class of organic sulfur derivatives (mercaptans) characterized by the presence of sulfhydryl residues. In biological systems, thiols have numerous functions, including a central role in coordinating the antioxidant defense network. Physical exercise may induce oxidative stress. In humans, a consistent marker of exercise-induced oxidative stress is blood glutathione oxidation. Physical training programs have specific effects on tissue glutathione metabolism that depend on the work program and the type of tissue. Experimental studies show that glutathione metabolism in several tissues sensitively responds to an exhaustive bout of exercise. Study of glutathione-deficient animals clearly indicates the central importance of having adequate tissue glutathione to protect against exercise-induced oxidative stress. Among the various thiol supplements studied, N-acetyl-L-cysteine and alpha-lipoic acid hold the most promise. These agents may have antioxidant effects at the biochemical level but are also known to influence redox-sensitive cell signaling.

Massive loss of sulfur in HIV infection

Skeletal muscle tissue from SIV-infected macaques was previously found to contain abnormally high sulfate and low glutathione levels indicative of an excessive cysteine catabolism. We now confirm the peripheral tissue as a site of massive cysteine catabolism in HIV infection and have determined the urinary loss of sulfur per time unit. The comparison of the sulfate concentrations of the arterial and venous blood from the lower extremities of 16 symptomatic HIV+ patients and 18 HIV- control subjects (study 1) revealed (1) that the peripheral tissue of HIV+ patients with or without highly active antiretroviral therapy (HAART) releases large amounts of sulfate and (2) that plasma sulfate, thioredoxin, and interleukin-6 levels are elevated in these patients. A complementary investigation of 64 asymptomatic HIV+ patients and 65 HIV- subjects (study 2) revealed increased plasma sulfate levels in the asymptomatic patients. The analysis of the daily urinary excretion of sulfate and urea of another group of 19 HIV+ patients and 22 healthy HIV- subjects (study 3) confirmed (1) that HIV+ patients experience a massive loss of sulfur and (2) that this loss is not ameliorated by HAART. The sulfur loss of asymptomatic patients was equivalent to a mean loss of about 10 g of cysteine per day. If extrapolated, this would correspond to an alarming negative balance of approximately 2 kg of cysteine per year under the assumption that the normal sulfate excretion equivalent to approximately 3 g of cysteine per day is balanced by a standard Western diet. The abnormally high sulfate/urea ratio suggests that this process drains largely the glutathione pool.

Genetic and metabolic control of the mitochondrial transmembrane potential and reactive oxygen intermediate production in HIV disease

Redox mechanims play important roles in replication of human immunodeficiency virus type 1 (HIV-1) and cellular susceptibility to apoptosis signals. Viral replication and accelerated turnover of CD4+ T cells occur throughout a prolonged asymptomatic phase in patients infected by HIV-1. Disease development is associated with steady loss of CD4+ T cells by apoptosis, increased rate of opportunistic infections and lymphoproliferative diseases, disruption of energy metabolism, and generalized wasting. Such pathological states are preceded by: (i) depletion of intracellular antioxidants, glutathione (GSH) and thioredoxin (TRX), (ii) increased reactive oxygen species (ROS) production, and (iii) changes in mitochondrial transmembrane potential (deltapsi(m)). Disruption of deltapsi(m) appears to be the point of no return in the effector phase of apoptosis. Viral proteins Tat, Nef, Vpr, protease, and gp120, have been implicated in initiation and/or intensification of oxidative stress and disruption of deltapsi(m). Redox-sensitive transcription factors, NF-kappaB, AP-1, and p53, support expression of viral genes and proinflammatory lymphokines. ROS regulate apoptosis signaling through Fas, tumor necrosis factor (TNF), and related cell death receptors, as well as the T-cell receptor. Oxidative stress in HIV-infected donors is accompanied by increased glucose utilization both on the cellular and organismal levels. Generation of GSH and TRX from their corresponding oxidized forms is dependent on NADPH provided through the pentose phosphate pathway of glucose metabolism. This article seeks to delineate the genetic and metabolic bases of HIV-induced oxidative stress. Such understanding should lead to development of effective antioxidant therapies in HIV disease.

N-acetyl-cysteine in the therapy of HIV-positive patients

Randomly selected asymptomatic HIV-positive persons reveal, on average, a massive daily loss of sulphur, which appears to represent in first approximation the mean loss throughout the asymptomatic stage, and may explain the widely observed decrease in cyst(e)ine and glutathione levels. This sulphur loss is reasonably expected to lead, within a few years, to a life-threatening condition and may, therefore, contribute decisively to disease progression. Importantly, the rate of sulphur loss is not ameliorated by highly active antiretroviral therapy and may contribute to antiretroviral treatment failure. Several clinical trials on N-acetyl-cysteine treatment of HIV-positive patients have revealed various therapeutic effects, but did not meet the rigorous standards for approval by the health authorities.

Determination of cellular thiol levels in individual viable lymphocytes by means of fluorescence intensity and polarization

Cellular thiol levels regulate lymphocyte proliferation and death and play a significant role in the immune response. Therefore, the ability to analyze the total protein and non-protein thiol compounds and their distribution among individual living lymphocytes is of great importance. A quantitative measurement of intracellular sulphydryl groups in living lymphocytes using the Cellscan mark F (CS-F) cytometer, in conjunction with the probe CMFDA, is described. This technique permits the detection, identification, and study of sub-populations and single cells in a sample of heterogeneous lymphocytes. The Cellscan apparatus is a laser based scanning cytometer incorporating a unique cell carrier which allows repeated, high-precision measurements of fluorescence intensity (FI) and fluorescence polarization (FP) to be made on intact individual living cells under controlled physiological conditions. The discernible effect of fluorophore molecules bound to thiols having a higher FP than free molecules was used to estimate their relative fractions in living lymphocytes. The results were more conspicuous when the ratio between FP measured at two wavelengths (FPR) of the fluorogenic molecules was used for analysis. In addition, the intracellular dynamic changes in the FI, FP and FPR of the fluorescent probe were also monitored. The cellular sulphydryl content of each lymphocyte within a population was recorded by the CS-F, and sub-populations or individual cells were classified according to their thiol levels and their metabolic rates. Changes in thiol concentration were observed following mitogenic activation of peripheral lymphocytes.

Management of HIV-infected pregnant patients in malaria-endemic areas: therapeutic and safety considerations in concomitant use of antiretroviral and antimalarial agents

Chemotherapy in pregnancy is an intricate process requiring prudent use of pharmacologic agents. Malarial infection during pregnancy is often fatal, and prophylaxis against the causative parasite necessitates rational therapeutic intervention. Various agents have been used for prophylaxis against malaria during pregnancy, including chloroquine, mefloquine, proguanil, pyrimethamine, and pyrimethamine-sulfadoxine. Use of these agents has been based on a risk-benefit criterion, without appropriate toxicologic or teratologic evaluation. Some of the aforementioned prophylactic agents have been shown to alter glutathione levels and may exacerbate the oxidation-reduction imbalance attendant on HIV infection. HIV-infected patients traveling to or residing in malaria-endemic areas require protection from malarial infection to avoid placing themselves in double jeopardy. Zidovudine (AZT) is recommended for the prevention of vertical transmission of HIV-1 from mother to child. Other agents, such as lamivudine alone or in combination with AZT, nevirapine, or the HIV-1 protease inhibitors, are either being considered or are currently undergoing trials for use in preventing vertical transmission of HIV-1 or managing HIV infection in infants and children. Although the potential for antimalarial agents to cause congenital malformations is low when they are used alone, their ability to cause problems when combined with antiretroviral drugs needs to be evaluated. In developing countries that have high birth rates, a high endemicity of malaria, and alarming rates of new cases of HIV, prophylaxis against both diseases with combination agents during pregnancy is a challenge.

Cysteine and glutathione in catabolic conditions and immunological dysfunction

The conspicuous increase in the plasma cysteine disulphide/thiol ratio in elderly persons and cancer patients indicates a shift of the plasma redox state. The most important redox buffers in skeletal muscle tissue and blood plasma, i.e. glutathione and albumin, respectively, are significantly decreased in different models of cachexia. Treatment with N-acetyl cysteine, i.e. a thiol-containing antioxidant, was found to increase the plasma albumin level and to ameliorate the loss of body cell mass in cancer patients and healthy individuals. The treatment of HIV infection with N-acetyl cysteine, in contrast, serves mainly as a tool to ameliorate the physiological and immunological consequences of the virus-induced cysteine deficiency.

The role of oxidative imbalance in progression to AIDS: effect of the thiol supplier N-acetylcysteine

In this study we investigate the redox profile of HIV+ patients at different stages of disease with regard to immunological parameters, i.e., the number of circulating CD4+ and CD8+ lymphocytes. For this purpose, peripheral blood mononuclear cells (PBMCs) obtained from healthy donors, HIV+ patients in the asymptomatic phase, long-term nonProgressors (LTNPs), and AIDS patients have been considered. Cells have been exposed in vitro to the prooxidizing agent menadione, which is able to induce superoxide anion formation, and the susceptibility of the cells to the induced oxidative stress was estimated. Moreover, the possibility that the susceptibility of the cells to oxidative stress might be reduced by preexposing them to the antioxidizing agent N-acetylcysteine (NAC) has also been analyzed. The results obtained can be summarized as follows: (1) treatment with the prooxidant agent is capable of inducing massive morphological alterations in PBMCs. In particular, a significant correlation was found between the decrease in number of CD4+ lymphocytes in patients at different stages of disease and the susceptibility of their PBMCs to oxidative stress; (2) preincubation with NAC was able to preserve partially the ultrastructural characteristics of PBMCs isolated from HIV+ patients. In particular, a direct relationship was found between the efficacy of NAC protection and CD4 counts; (3) evaluation of the plasma index of peroxidation and the number of circulating CD4 lymphocytes indicates the existence of a positive correlation between "systemic" oxidative imbalance and stage of the disease; and (4) cells from LTNPs display either oxidative susceptibility or oxidative markers similar to those of healthy donor cells. Our study suggests that the redox profile of patients may be considered a predictive marker of AIDS progression and that the acute infection and the asymptomatic phase of the disease may represent a useful period in which the combined use of antiretroviral and antioxidant drugs may be beneficial.

A phase I/II evaluation of oral L-2-oxothiazolidine-4-carboxylic acid in asymptomatic patients infected with human immunodeficiency virus

A randomized double-blind, placebo-controlled study was conducted in 37 asymptomatic HIV-infected individuals (mean CD4 count 707 cells/mm3) to characterize the safety, pharmacokinetics, and effect on blood thiols of three dosage levels of a cysteine prodrug, L-2-oxothiazolidine-4-carboxylic acid (OTC; Procysteine; Clintec Technologies, Deerfield, IL). Single-dose administration of OTC resulted in measurable plasma levels at all dosages, with a mean peak plasma concentration of 734 +/- 234 nmol/mL at the highest dosage studied. After 4 weeks of administration three times daily, a statistically significant increase was seen in whole blood glutathione in the 1,500 mg and 3,000 mg dose groups compared with the placebo group. A significant increase in whole blood cysteine and peripheral blood mononuclear cell (PBMC) glutathione was not seen during the study period.