Inhibition of murine AIDS by pro-glutathione (GSH) molecules

Multiple antimicrobial and immune-modulating activities of cysteamine in infectious diseases

Infectious diseases are a major threat to global health and cause millions of deaths every year, particularly in developing countries. The emergence of multidrug resistance challenges current antimicrobial treatments, inducing uncertainty in therapeutic protocols. New compounds are therefore necessary. A drug repurposing approach could play a critical role in developing new treatments used either alone or in combination with standard therapy regimens. Herein, we focused on cysteamine, an aminothiol endogenously synthesized by human cells during the degradation of coenzyme-A, which is a drug approved for the treatment of nephropathic cystinosis. Cysteamine influences many biological processes due to the presence of the highly reactive thiol group. This review provides an overview of cysteamine-mediated effects on different viruses, bacteria and parasites, with a particular focus on infections caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Mycobacterium tuberculosis, non-tuberculous mycobacteria (NTM), and Pseudomonas aeruginosa. Evidences for a potential use of cysteamine as a direct antimicrobial agent and/or a host-directed therapy, either alone or in combination with other antimicrobial drugs, are described.

Design, synthesis and anti-NASH effect evaluation of novel GFT505 derivatives in vitro and in vivo

Non-alcoholic fatty liver disease (NAFLD) is emerging as the largest burden of chronic liver disease worldwide. Nonalcoholic steatohepatitis (NASH) is a progressive form of NAFLD that can progress to cirrhosis and hepatocellular carcinoma. Unfortunately, current treatment options for NASH are very limited. Among the multiple pathways of NASH, peroxisome proliferators-activated receptors (PPARS) are recognized as an important and effective target. GFT 505 is a dual excitement agent for the treatment of PPAR-α/δ for the treatment of NASH. However, its activity and toxicity need to be further improved. Therefore, here we would like to report the design, synthesis and biological evaluation of 11 GFT 505 derivatives. The initial cytotoxicity through proliferation activity of HepG2 cells and in vitro anti-NASH activity evaluation demonstrated that under the same concentration, the compound 3d possess significantly lower cytotoxicity and better anti-NASH activity than that of GFT 505. Moreover, Molecular docking also shows that 3d and PPAR-α/δ can form a stable hydrogen bond and have the lowest binding energy. Therefore this novel molecule 3d was selected to go further in vivo investigation. Methionine-choline deficiency (MCD) induced C57BL/6J NASH model mice was used for the in vivo biological experiments and the compound 3d demostrated lower liver toxicity than that of GFT 505 in the body at the same dose, and it did more effectively improve hyperlipidemia, liver fat degeneration and liver inflammation as well as significantly enhance the content of the GSH which is inportant for the liver protection. This study suggested that the compound 3d is a very promising lead compound for the treatment of NASH.

Magnetic fields as inducer of glutathione and peroxidase production by Saccharomyces cerevisiae

Glutathione (GSH) and peroxidase (POD) are biomolecules of interest in the global market; thus, it is desirable to seek ways to increase their production. Magnetic field (MF) application is one of the technologies used in cultivation that has shown promising results to increase bioproducts. Therefore, this study aimed at evaluating the influence of MFs on GSH and POD production by Saccharomyces cerevisiae ATCC 7754. Different periods of MF application (35 mT) were evaluated over 72 h. The highest GSH production was reached in 48 h of cultivation in assays MF 0-24 (155.32 ± 9.12 mg L-1) and MF 0-72 (149.27 ± 3.62 mg L-1), which showed an increase of 121.9 % and 113 %, respectively, by comparison with the control without any MF application. The highest POD activity was achieved when MFs were applied throughout the culture (36.31 U mg-1) and POD productivity of 0.72 U mg-1 h-1. MF application throughout cultivation proved to be a promising strategy since all responses increased, i.e., GSH concentration, GSH productivity, POD activity, and POD productivity increased 113.7 %, 113 %, 20.4 %, and 28.6 %, respectively. This study is one of the first to consider MFs as a viable and low-cost alternative to produce GSH and POD in bioprocesses.

Liposomes as Carriers for the Delivery of Efavirenz in Combination with Glutathione—An Approach to Combat Opportunistic Infections

Human immunodeficiency virus (HIV)-infected individuals display an enhanced production of reactive oxygen species (ROS). This reduction of antioxidant capacity in host tissues has been related to the decrease in total levels of ROS scavengers such as glutathione (GSH). Prevention of opportunistic infections due to a weakened immune system is becoming a key strategy along with HIV elimination. Research in these directions is clearly warranted, especially a combination of antiretrovirals and antioxidants to ameliorate oxidative stress, improve intracellular uptake and target viral reservoirs. Hence, we aimed to formulate liposomes loaded with the antiretroviral drug efavirenz (EFA) in the presence of glutathione, as these carriers can be engineered to enhance the ability to reach the target reservoirs. The goal of the present work was to investigate the intracellular uptake of EFA-loaded liposome (with and without GSH) by human monocytic leukemia cells (THP-1 cells) and examine cell viability and ROS scavenging activity. Results obtained provided significant data as follows: (i) treatment with EFA and GSH combination could enhance the uptake and reduce cytotoxicity; (ii) encapsulation of EFA into liposomes increased its levels in the macrophages, which was further enhanced in the presence of GSH; (iii) delivery of EFA in the presence of GSH quenched the intracellular ROS, which was significantly higher when delivered via liposomes. Data revealed that a combination of EFA and GSH encompasses advantages; hence, GSH supplementation could be a safe and cost-effective treatment to slow the development of HIV infection and produce an immune-enhancing effect.

Metabolomic Analysis of the Urine from Rats with Collagen-Induced Arthritis with the Effective Part of Caulophyllum robustum Maxim

Rheumatoid arthritis (RA) is a chronic autoimmune disease with high incidence and high disability and recurrence rates. Caulophyllum robustum Maxim (C. robustum) is a traditional Chinese medicine (TCM) with main effective parts (CRME) commonly used for RA treatment. To explore the mechanism of CRME in RA, we used metabolomics to investigate the effect of CRME intervention on urine metabolism in rats with collagen-induced arthritis (CIA). CIA rats were randomly divided into normal control, CIA model, and CRME groups. A metabolomics approach, using Ultra-Performance Liquid Chromatography-Quadrupole-Time-of-Flight/Mass Spectrometry, was developed to perform urinary metabolic profiling. Differential metabolites were identified by comparing the CIA model and CRME groups. Preliminarily, 56 significant differential metabolites were identified in urine, and 20 metabolic pathways were disturbed by the CIA. The amount of 16 different metabolites changed in urine after CRME intervention. The production of these metabolites involves tryptophan, tyrosine, energy, cholesterol, and vitamin metabolism. CRME has anti-inflammatory and immunosuppressive effects in CIA model rats. By examining the endogenous metabolite levels, we identified potential CRME targets and pathways involved in the treatment of RA. The results of our metabolic studies indicate that CRME regulates amino acid, vitamin, energy, and lipid metabolism pathways to treat RA and may provide a new explanation for the anti-RA mechanism of CRME.

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

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

I-152, a supplier of N-acetyl-cysteine and cysteamine, inhibits immunoglobulin secretion and plasma cell maturation in LP-BM5 murine leukemia retrovirus-infected mice by affecting the unfolded protein response

Excessive production of immunoglobulins (Ig) causes endoplasmic reticulum (ER) stress and triggers the unfolded protein response (UPR). Hypergammaglobulinemia and lymphadenopathy are hallmarks of murine AIDS that develops in mice infected with the LP-BM5 murine leukemia retrovirus complex. In these mice, Th2 polarization and aberrant humoral response have been previously correlated to altered intracellular redox homeostasis. Our goal was to understand the role of the cell's redox state in Ig secretion and plasma cell (PC) maturation. To this aim, LP-BM5-infected mice were treated with I-152, an N-acetyl-cysteine and cysteamine supplier. Intraperitoneal I-152 administration (30 μmol/mouse three times a week for 9 weeks) decreased plasma IgG and increased IgG/Syndecan 1 ratio in the lymph nodes where IgG were in part accumulated within the ER. PC containing cytoplasmic inclusions filled with IgG were present in all animals, with fewer mature PC in those treated with I-152. Infection induced up-regulation of signaling molecules involved in the UPR, i.e. CHAC1, BiP, sXBP-1 and PDI, that were generally unaffected by I-152 treatment except for PDI and sXBP-1, which have a key role in protein folding and PC maturation, respectively. Our data suggest that one of the mechanisms through which I-152 can limit hypergammaglobulinemia in LP-BM5-infected mice is by influencing IgG folding/assembly as well as secretion and affecting PC maturation.

Redox-Modulating Agents in the Treatment of Viral Infections

Viruses use cell machinery to replicate their genome and produce viral proteins. For this reason, several intracellular factors, including the redox state, might directly or indirectly affect the progression and outcome of viral infection. In physiological conditions, the redox balance between oxidant and antioxidant species is maintained by enzymatic and non-enzymatic systems, and it finely regulates several cell functions. Different viruses break this equilibrium and induce an oxidative stress that in turn facilitates specific steps of the virus lifecycle and activates an inflammatory response. In this context, many studies highlighted the importance of redox-sensitive pathways as novel cell-based targets for therapies aimed at blocking both viral replication and virus-induced inflammation. In the review, we discuss the most recent findings in this field. In particular, we describe the effects of natural or synthetic redox-modulating molecules in inhibiting DNA or RNA virus replication as well as inflammatory pathways. The importance of the antioxidant transcription factor Nrf2 is also discussed. Most of the data reported here are on influenza virus infection. We believe that this approach could be usefully applied to fight other acute respiratory viral infections characterized by a strong inflammatory response, like COVID-19.

Boosting GSH Using the Co-Drug Approach: I-152, a Conjugate of N-acetyl-cysteine and β-mercaptoethylamine

Glutathione (GSH) has poor pharmacokinetic properties; thus, several derivatives and biosynthetic precursors have been proposed as GSH-boosting drugs. I-152 is a conjugate of N-acetyl-cysteine (NAC) and S-acetyl-β-mercaptoethylamine (SMEA) designed to release the parent drugs (i.e., NAC and β-mercaptoethylamine or cysteamine, MEA). NAC is a precursor of L-cysteine, while MEA is an aminothiol able to increase GSH content; thus, I-152 represents the very first attempt to combine two pro-GSH molecules. In this review, the in-vitro and in-vivo metabolism, pro-GSH activity and antiviral and immunomodulatory properties of I-152 are discussed. Under physiological GSH conditions, low I-152 doses increase cellular GSH content; by contrast, high doses cause GSH depletion but yield a high content of NAC, MEA and I-152, which can be used to resynthesize GSH. Preliminary in-vivo studies suggest that the molecule reaches mouse organs, including the brain, where its metabolites, NAC and MEA, are detected. In cell cultures, I-152 replenishes experimentally depleted GSH levels. Moreover, administration of I-152 to C57BL/6 mice infected with the retroviral complex LP-BM5 is effective in contrasting virus-induced GSH depletion, exerting at the same time antiviral and immunomodulatory functions. I-152 acts as a pro-GSH agent; however, GSH derivatives and NAC cannot completely replicate its effects. The co-delivery of different thiol species may lead to unpredictable outcomes, which warrant further investigation.

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.

Glutathione and glutathione derivatives in immunotherapy

Reduced glutathione (GSH) is the most prevalent non-protein thiol in animal cells. Its de novo and salvage synthesis serves to maintain a reduced cellular environment, which is important for several cellular functions. Altered intracellular GSH levels are observed in a wide range of pathologies, including several viral infections, as well as in aging, all of which are also characterized by an unbalanced Th1/Th2 immune response. A central role in influencing the immune response has been ascribed to GSH. Specifically, GSH depletion in antigen-presenting cells (APCs) correlates with altered antigen processing and reduced secretion of Th1 cytokines. Conversely, an increase in intracellular GSH content stimulates IL-12 and/or IL-27, which in turn induces differentiation of naive CD4+ T cells to Th1 cells. In addition, GSH has been shown to inhibit the replication/survival of several pathogens, i.e. viruses and bacteria. Hence, molecules able to increase GSH levels have been proposed as new tools to more effectively hinder different pathogens by acting as both immunomodulators and antimicrobials. Herein, the new role of GSH and its derivatives as immunotherapeutics will be discussed.

Glutathione Depletion Is Linked with Th2 Polarization in Mice with a Retrovirus-Induced Immunodeficiency Syndrome, Murine AIDS: Role of Proglutathione Molecules as Immunotherapeutics

Injection of the LP-BM5 murine leukemia virus into mice causes murine AIDS, a disease characterized by many dysfunctions of immunocompetent cells. To establish whether the disease is characterized by glutathione imbalance, reduced glutathione (GSH) and cysteine were quantified in different organs. A marked redox imbalance, consisting of GSH and/or cysteine depletion, was found in the lymphoid organs, such as the spleen and lymph nodes. Moreover, a significant decrease in cysteine and GSH levels in the pancreas and brain, respectively, was measured at 5 weeks postinfection. The Th2 immune response was predominant at all times investigated, as revealed by the expression of Th1/Th2 cytokines. Furthermore, investigation of the activation status of peritoneal macrophages showed that the expression of genetic markers of alternative activation, namely, Fizz1, Ym1, and Arginase1, was induced. Conversely, expression of inducible nitric oxide synthase, a marker of classical activation of macrophages, was detected only when Th1 cytokines were expressed at high levels. In vitro studies revealed that during the very early phases of infection, GSH depletion and the downregulation of interleukin-12 (IL-12) p40 mRNA were correlated with the dose of LP-BM5 used to infect the macrophages. Treatment of LP-BM5-infected mice with N-(N-acetyl-l-cysteinyl)-S-acetylcysteamine (I-152), an N-acetyl-cysteine supplier, restored GSH/cysteine levels in the organs, reduced the expression of alternatively activated macrophage markers, and increased the level of gamma interferon production, while it decreased the levels of Th2 cytokines, such as IL-4 and IL-5. Our findings thus establish a link between GSH deficiency and Th1/Th2 disequilibrium in LP-BM5 infection and indicate that I-152 can be used to restore the GSH level and a balanced Th1/Th2 response in infected mice.

IMPORTANCE

The first report of an association between Th2 polarization and alteration of the redox state in LP-BM5 infection is presented. Moreover, it provides evidence that LP-BM5 infection causes a decrease in the thiol content of peritoneal macrophages, which can influence IL-12 production. The restoration of GSH levels by GSH-replenishing molecules can represent a new therapeutic avenue to fight this retroviral infection, as it reestablishes the Th1/Th2 balance. Immunotherapy based on the use of pro-GSH molecules would permit LP-BM5 infection and probably all those viral infections characterized by GSH deficiency and a Th1/Th2 imbalance to be more effectively combated.

Intracellular redox state as target for anti-influenza therapy: are antioxidants always effective?

Influenza virus infections represent a big issue for public health since effective treatments are still lacking. In particular, the emergence of strains resistant to drugs limits the effectiveness of anti-influenza agents. For this reason, many efforts have been dedicated to the identification of new therapeutic strategies aimed at targeting the virus-host cell interactions. Oxidative stress is a characteristic of some viral infections including influenza. Because antioxidants defend cells from damage caused by reactive oxygen species induced by different stimuli including pathogens, they represent interesting molecules to fight infectious diseases. However, most of the available studies have found that these would-be panaceas could actually exacerbate the diseases they claim to prevent, and have thus revealed "the dark side" of these molecules. This review article discusses the latest opportunities and drawbacks of the antioxidants used in anti-influenza therapy and new perspectives.

The effects of human immunodeficiency virus infection on the expression of the drug efflux proteins P-glycoprotein and breast cancer resistance protein in a human intestine model

OBJECTIVES

In human immunodeficiency virus (HIV) infection, decreased penetration of antiretroviral drugs is postulated to contribute to HIV persistence within lymphoid-rich regions of the gastrointestinal (GI) tract. However, mechanistic explanations for this phenomenon remain unclear. Specifically, investigations of HIV effects on drug efflux proteins within intestinal models are minimal.

METHODS

Using an in-vitro co-culture model of the GI tract, the effects of HIV infection on drug efflux proteins, P-glycoprotein and breast cancer resistance protein (BCRP) were evaluated. The influence of the HIV-1 protein, Tat, and oxidative stress on P-glycoprotein and BCRP was also evaluated.

KEY FINDINGS

P-glycoprotein expression demonstrated an HIV-induced upregulation in Caco-2 cells over time for cells grown in co-culture with resting lymphocytes. BCRP overall expression increased with HIV exposure in activated primary human lymphocytes co-cultured with Caco-2 cells. Tat treatment resulted in no significant alterations in P-glycoprotein (43% increase), BCRP expression, or oxidative stress.

CONCLUSIONS

HIV exposure within an in-vitro intestinal model resulted in increases in P-glycoprotein and BCRP in a cell-specific manner. Additionally, observed changes were not mediated by Tat. Collectively, these results suggest that alterations in BCRP and P-glycoprotein may contribute, in part, to decreased antiretroviral concentrations within the gut-associated lymphoid tissue of the GI tract in HIV infection.

Pyrrolidine dithiocarbamate inhibits enterovirus 71 replication by down-regulating ubiquitin-proteasome system

Enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD). The severe neurological complications caused by EV71 infection and the lack of effective therapeutic medicine underline the importance of searching for antiviral substances. Pyrrolidine dithiocarbamate (PDTC), an antioxidant, has been reported to inhibit the replication of coxsackievirus B (CVB) through dysregulating ubiquitin-proteasome system (UPS). In this study, we demonstrated that PDTC exerted potent antiviral effect on EV71. Viral RNA synthesis, viral protein expression, and the production of viral progeny were significantly reduced by the treatment of PDTC in Vero cells infected with EV71. Similar to the previous report about the inhibitory effect of PDTC on UPS, we found that PDTC treatment led to decreased levels of polyubiquitinated proteins in EV71-infected cells. The inhibitory effect of PDTC on UPS was further confirmed by the increased accumulation of cell cycle regulatory proteins p21 and p53, which are normally degraded through UPS, while the expression levels of both proteins remained unchanged. We also showed that PDTC had no impact on the activity of proteasome. Thus, we demonstrated that the down-regulation of PDTC on UPS was the result of its inhibition on ubiquitination. More importantly, this study provides evidence that the inhibition on UPS was required for the antiviral activity of PDTC, since MG132, a potent proteasome inhibitor, significantly inhibited the cytopathic effect and viral protein synthesis in EV71-infected cells. We also found that the antioxidant property of PDTC did not contribute to its antiviral effect, since N-acetyl-l-cysteine, a potent antioxidant, could not inhibit viral replication. In addition, CPE and viral protein synthesis were not inhibited in the cells pretreated with PDTC 2h before viral infection and then cultured in the media with no PDTC supplement, while the antioxidant effect of PDTC was retained. PDTC also showed significant inhibition on apoptosis induced by EV71 infection when it was applied at the early stage of viral infection. Our results collectively suggest that PDTC could be a potential anti-EV71 compound which possesses both antiviral and anti-apoptotic capacity.

Inhibition of rotavirus ECwt infection in ICR suckling mice by N-acetylcysteine, peroxisome proliferator-activated receptor gamma agonists and cyclooxygenase-2 inhibitors

Live attenuated vaccines have recently been introduced for preventing rotavirus disease in children. However, alternative strategies for prevention and treatment of rotavirus infection are needed mainly in developing countries where low vaccine coverage occurs. In the present work, N-acetylcysteine (NAC), ascorbic acid (AA), some nonsteroidal anti-inflammatory drugs (NSAIDs) and peroxisome proliferator-activated receptor gamma (PPARγ) agonists were tested for their ability to interfere with rotavirus ECwt infectivity as detected by the percentage of viral antigen-positive cells of small intestinal villi isolated from ECwt-infected ICR mice. Administration of 6 mg NAC/kg every 8 h for three days following the first diarrhoeal episode reduced viral infectivity by about 90%. Administration of AA, ibuprofen, diclofenac, pioglitazone or rosiglitazone decreased viral infectivity by about 55%, 90%, 35%, 32% and 25%, respectively. ECwt infection of mice increased expression of cyclooxygenase-2, ERp57, Hsc70, NF-κB, Hsp70, protein disulphide isomerase (PDI) and PPARγ in intestinal villus cells. NAC treatment of ECwt-infected mice reduced Hsc70 and PDI expression to levels similar to those observed in villi from uninfected control mice. The present results suggest that the drugs tested in the present work could be assayed in preventing or treating rotaviral diarrhoea in children and young animals.

S-D-Lactoylglutathione can be an alternative supply of mitochondrial glutathione

The mitochondrial pool of GSH (glutathione) is considered the major redox system in maintaining matrix redox homeostasis, preserving sulfhydryl groups of mitochondrial proteins in appropriate redox state, in defending mitochondrial DNA integrity and protecting mitochondrial-derived ROS, and in defending mitochondrial membranes against oxidative damage. Despite its importance in maintaining mitochondrial functionality, GSH is synthesized exclusively in the cytoplasm and must be actively transported into mitochondria. In this work we found that SLG (S-D-lactoylglutathione), an intermediate of the glyoxalase system, can enter the mitochondria and there be hydrolyzed from mitochondrial glyoxalase II enzyme to D-lactate and GSH. To demonstrate SLG transport from cytosol to mitochondria we used radiolabeled compounds and the results showed two different kinetic curves for SLG or GSH substrates, indicating different kinetic transport. Also, the incubation of functionally and intact mitochondria with SLG showed increased GSH levels in normal mitochondria and in artificially uncoupled mitochondria, demonstrating transport not linked to ATP presence. As well mitochondrial-swelling assay confirmed SLG entrance into organelles. Moreover we observed oxygen uptake and generation of membrane potential probably linked to D-lactate oxidation which is a product of SLG hydrolysis. The latter data were confirmed by oxidation of D-lactate in mitochondria evaluated by measuring mitochondrial D-lactate dehydrogenize activity. In this work we also showed the presence of mitochondrial glyoxalase II in inter-membrane space and mitochondrial matrix and we investigated the role of SLG in whole cells. In conclusion, this work showed new alternative sources of GSH supply to the mitochondria by SLG, an intermediate of the glyoxalase system.

Molecules altering the intracellular thiol content modulate NF-kB and STAT-1/IRF-1 signalling pathways and IL-12 p40 and IL-27 p28 production in murine macrophages

BACKGROUND

The aim of this study was to investigate the molecular mechanisms involved in the production of Th1 cytokines, namely IL-12 and IL-27, when the intra-macrophage redox state was altered by different chemical entities such as GSH-C4, which is reduced glutathione carrying an aliphatic chain, or I-152, a pro-drug of N-acetyl-cysteine (NAC) and beta-mercaptoethylamine. We had already demonstrated that GSH-C4 and I-152 could shift the immune response towards Th1 in Ovalbumin-immunized mice as well as enhance Th1 response in HIV-1 Tat-immunized mice.

METHODOLOGY/PRINCIPAL FINDINGS

By a new high performance liquid chromatography method, we found that 20 mM GSH-C4 provided a number of thiol species in the form of GSH, while 20 mM I-152 decreased GSH and increased the thiols in the form of NAC and I-152. Under these experimental conditions, GSH-C4 and I-152 enhanced and suppressed respectively the mRNA expression levels of IL-12 p40 induced by LPS/IFN-γ as assessed by Real-Time PCR. The protein production of IL-12 p40 was increased by GSH-C4 and decreased by I-152 as determined by Enzyme-linked immunosorbent assay. Western immunoblot and electrophoretic mobility shift assays revealed that Nuclear Factor -kB (NF-kB) activation was inhibited by I-152 and prolonged by GSH-C4. Twenty mM I-152 stimulated IL-27 p28 gene expression and sustained Signal Transducer and Activator of Transcription (STAT)-mediated interferon regulator factor 1 (IRF-1) de novo synthesis. By contrast, 20 mM GSH-C4 did not exert any effect on IL-27 p28 gene expression.

CONCLUSIONS AND SIGNIFICANCE

an increase in the intra-macrophage redox state by GSH-C4 and I-152 enhances Th1 cytokine production although the chemical structure and the intra-cellular metabolism influence differently signalling pathways involved in IL-27 or IL-12 production. GSH-C4 and I-152 may be used as Th1 immunomodulators in some pathologies and in ageing where GSH depletion may contribute to the Th1/Th2 imbalance, and in new immunization strategies.

The HIV-1 transactivator factor (Tat) induces enterocyte apoptosis through a redox-mediated mechanism

The intestinal mucosa is an important target of human immunodeficiency virus (HIV) infection. HIV virus induces CD4+ T cell loss and epithelial damage which results in increased intestinal permeability. The mechanisms involved in nutrient malabsorption and alterations of intestinal mucosal architecture are unknown. We previously demonstrated that HIV-1 transactivator factor (Tat) induces an enterotoxic effect on intestinal epithelial cells that could be responsible for HIV-associated diarrhea. Since oxidative stress is implicated in the pathogenesis and morbidity of HIV infection, we evaluated whether Tat induces apoptosis of human enterocytes through oxidative stress, and whether the antioxidant N-acetylcysteine (NAC) could prevent it. Caco-2 and HT29 cells or human intestinal mucosa specimens were exposed to Tat alone or combined with NAC. In an in-vitro cell model, Tat increased the generation of reactive oxygen species and decreased antioxidant defenses as judged by a reduction in catalase activity and a reduced (GSH)/oxidized (GSSG) glutathione ratio. Tat also induced cytochrome c release from mitochondria to cytosol, and caspase-3 activation. Rectal dialysis samples from HIV-infected patients were positive for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine. GSH/GSSG imbalance and apoptosis occurred in jejunal specimens from HIV-positive patients at baseline and from HIV-negative specimens exposed to Tat. Experiments with neutralizing anti-Tat antibodies showed that these effects were direct and specific. Pre-treatment with NAC prevented Tat-induced apoptosis and restored the glutathione balance in both the in-vitro and the ex-vivo model. These findings indicate that oxidative stress is one of the mechanism involved in HIV-intestinal disease.

Prodrug approach for increasing cellular glutathione levels

Reduced glutathione (GSH) is the most abundant non-protein thiol in mammalian cells and the preferred substrate for several enzymes in xenobiotic metabolism and antioxidant defense. It plays an important role in many cellular processes, such as cell differentiation, proliferation and apoptosis. GSH deficiency has been observed in aging and in a wide range of pathologies, including neurodegenerative disorders and cystic fibrosis (CF), as well as in several viral infections. Use of GSH as a therapeutic agent is limited because of its unfavorable biochemical and pharmacokinetic properties. Several reports have provided evidence for the use of GSH prodrugs able to replenish intracellular GSH levels. This review discusses different strategies for increasing GSH levels by supplying reversible bioconjugates able to cross the cellular membrane more easily than GSH and to provide a source of thiols for GSH synthesis.

The requirement of reactive oxygen intermediates for lymphocytic choriomeningitis virus binding and growth

Multiple viruses induce reactive oxygen intermediate (ROI) generation during infection that plays an important role in growth. We have examined the importance of ROI during lymphocytic choriomeningitis virus (LCMV) infection of immortalized BHK-21 cells and murine peritoneal macrophages. Within 15 min of virus addition, intracellular ROI levels increased. To examine the contribution of ROI to LCMV infection, cells were pretreated with antioxidant prior to virus addition. Antioxidant treatment inhibited low and high MOI growth of virus. The requirement for ROI was greatest during the initial phase of infection, as antioxidant treatment after 6 h post infection had a weaker inhibitory effect. Furthermore, antioxidant treatment of cells inhibited virus binding, while treatment of virus stocks with N-ethyl malemide, which blocks free thiols, eliminated infectious virus. This illustrates that ROI are critical to the regulation of virus binding and growth and has important implications for understanding the infectivity of related viruses.