N-acetylcysteine attenuates dimethylnitrosamine induced oxidative stress in rats

Ameliorative effects of hesperidin and N-acetylcysteine against formaldehyde-induced-hemato- and genotoxicity

This study investigated the hemato- and genotoxic effects of formaldehyde (FA) and the possible mitigating role of hesperidin (HP) and N-acetylcysteine (NAC), each alone and in combination. Sixty-four adult male albino rats were divided into eight equal groups; the study was conducted for 8 weeks; Group I (negative control: received no medication), Group II (positive control: received distilled water), Group III (received HP 50 mg/kg/day), Group IV (received NAC 50 mg/kg/day), Group V (received FA 10 mg/kg/day), Group VI (FA + HP), Group VII (FA + NAC), and Group VIII (FA + HP + NAC). Groups VI, VII, VIII received the same previously mentioned doses and for the same duration. All treatments were given by intraperitoneal administration. At the end of the study, complete blood count, oxidative stress, histopathological changes, immunohistochemical staining of inducible nitric oxide synthase, and proliferating cell nuclear antigen and genotoxicity by comet assay in the bone marrow of treated rats were assessed. FA administration caused significant hematotoxicity represented by elevated white blood cell numbers and serum malondialdehyde levels and reduced red blood cell numbers, platelets, and serum superoxide dismutase values. Histologically, it induced an increase in fat cell numbers in bone marrow tissue with a widening of marrow spaces and decreased cellularity of hematopoietic cells, megakaryocytes, and granulocytes. FA exposure significantly decreased immunoreactivity for proliferating cell nuclear antigen, whereas the immunoreactivity for inducible nitric oxide synthase was increased. Genotoxicity, as measured by comet assay, revealed a significant increase in comet% and tail length in FA-treated group when compared with other groups. The cotreatment with HP and NAC revealed their ability to protect against hematological changes, oxidative damage, histopathological, and immunohistochemical changes, and genotoxicity induced by FA.

N-acetyl cysteine abates hepatorenal toxicities induced by perfluorooctanoic acid exposure in male rats

Ingestion of perfluorooctanoic acid (PFOA) elicits toxicities in the hepatorenal system. We investigated the effect of PFOA and N-acetylcysteine (NAC) on the hepatorenal function of rats treated thus: control, PFOA (5 mg/kg), NAC (50 mg/kg), PFOA + NAC (5 and 25 mg/kg), and PFOA + NAC (5 and 50 mg/kg). We observed that NAC significantly (p < 0.05) reduced PFOA-induced increase in hepatic and renal function biomarkers of toxicities relative to PFOA alone and alleviated (p < 0.05) decreases in antioxidant status. Increases in oxidative stress and lipid peroxidation in PFOA-treated rats were reverted to normal by NAC and abated increased pro-inflammatory mediators, and decreased anti-inflammatory cytokine both in the hepatorenal system PFOA treated rats. Histology of the kidney and liver indicated that NAC, abated the severity of PFOA-induced damage significantly. Our findings affirm further that oxido-inflammatory mediators involved in PFOA-mediated toxicity can be effectively blocked by NAC through its antioxidant activity.

The Overactivation of NADPH Oxidase during Clonorchis sinensis Infection and the Exposure to N-Nitroso Compounds Promote Periductal Fibrosis

Clonorchis sinensis, a high-risk pathogenic human liver fluke, provokes various hepatobiliary complications, including epithelial hyperplasia, inflammation, periductal fibrosis, and even cholangiocarcinogenesis via direct contact with worms and their excretory-secretory products (ESPs). These pathological changes are strongly associated with persistent increases in free radical accumulation, leading to oxidative stress-mediated lesions. The present study investigated C. sinensis infection- and/or carcinogen N-nitrosodimethylamine (NDMA)-associated fibrosis in cell culture and animal models. The treatment of human cholangiocytes (H69 cells) with ESPs or/and NDMA increased reactive oxidative species (ROS) generation via the activation of NADPH oxidase (NOX), resulting in augmented expression of fibrosis-related proteins. These increased expressions were markedly attenuated by preincubation with a NOX inhibitor (diphenyleneiodonium chloride) or an antioxidant (N-acetylcysteine), indicating the involvement of excessive NOX-dependent ROS formation in periductal fibrosis. The immunoreactive NOX subunits, p47^phox and p67^phox, were observed in the livers of mice infected with C. sinensis and both infection plus NDMA, concomitant with collagen deposition and immunoreactive fibronectin elevation. Staining intensities are proportional to lesion severity and infection duration or/and NDMA administration. Thus, excessive ROS formation via NOX overactivation is a detrimental factor for fibrogenesis during liver fluke infection and exposure to N-nitroso compounds.

Amelioration of fenitrothion induced oxidative DNA damage and inactivation of caspase-3 in the brain and spleen tissues of male rats by N-acetylcysteine

N-acetylcysteine (NAC) has largely been used as an effective chemo- protective agent owing to their beneficial effect in restoring several physiological parameters and relieving oxidative stress. Interestingly, it has been suggested that NAC mechanisms of action extend beyond being a precursor to the antioxidant glutathione and that they may involve several neurotropic and inflammatory pathways. Exposure to fenitrothion, an organophosphorus insecticide, promotes oxidative stress and induces several deleterious changes in the immune response and various tissues including cerebrum and spleen. The main objective of our study was to investigate ameliorative efficacy of N-acetylcysteine for immunological and neurological alterations and oxidative DNA damage induced by fenitrothion toxicity in cerebrum and spleen tissues of male rats. Our results revealed that oral exposure to fenitrothion for 30 days caused a reduction in the erythrocyte count in addition to leukocytosis, lymphocytosis, and neutrophilia. Also, this route of administration increased the serum levels of LDH, TNF-α, and IL-2 with reduction in serum immunoglobulins (IgG & IgM) concentrations. Furthermore, a significant downregulation in the antioxidant markers (GSH & SOD) with an elevation of free radical (MDA) levels were noticed. Regarding the brain, fenitrothion administration inhibited AchE activity and increased brain GABA, serotonin and dopamine levels. Moreover, it induced an elevation in oxidative DNA damage indicated by 8-hydroxy 2-deoxyguanosine (8OH2dG) and mRNA expression of pro-apoptotic genes, including Bax, and p53, but Bcl-2 expression was reduced. N-acetylcysteine co-treatment restored the normal physiological tone in most of these parameters. Immunostaining for GFAP and Caspase-3 markers in the brain and spleen tissues were increased respectively. In conclusion, N-acetylcysteine supplementation has an ameliorative effect against immunotoxic, neurotoxic and oxidative DNA damage induced by fenitrothion exposure.

Hepatorenal protective effects of taurine and N-acetylcysteine against fipronil-induced injuries: The antioxidant status and apoptotic markers expression in rats

Fipronil (FPN), a commonly used phenylpyrazole pesticide can induce oxidative tissue damage following hazard usage. Due to the extensive household and commercial usage of FPN, its toxic effects on mammals received considerable attention. Finding the proper antioxidant that can overcome FPN-induced damage is essential. Therefore, the present study aimed to assess the hepatorenal ameliorative outcomes of N-acetyl cysteine (NAC) and taurine (TAU) against hepatorenal damage induced by FPN in male Wistar rats. Compared to control rats, oral FPN (at a dose of 19.4 mg kg^-1 BW for five successive days) significantly increased serum activities (p ≤ 0.05) of alkaline phosphatase, lactate dehydrogenase and transaminases, in addition to total cholesterol, urea and creatinine levels. Moreover, FPN provoked oxidative damage indicated by increased malondialdehyde and nitric oxide formation and decreased glutathione concentration and activities of enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and catalase) in the hepatic and renal tissues. Furthermore, FPN administration induced overexpression of the proapoptotic (Bax), while it downregulated the expression of the anti-apoptotic (Bcl-2) protein. Interestingly, oral administration of TAU (50 mg Kg^-1 BW) and NAC (50 mg Kg^-1 BW), alone or in combination, five days prior to and five days along with FPN administration, significantly ameliorated (p ≤ 0.05) and normalized the harmful effects of FPN on serum biomarkers of hepatorenal injury, lipid peroxidation and tissue antioxidants. In conclusion, TAU and NAC, alone or in combination, provided significant hepatorenal protection against oxidative stress and apoptosis induced by FPN.

Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine

Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.

Combination of anti-tuberculosis drugs with vitamin C or NAC against different Staphylococcus aureus and Mycobacterium tuberculosis strains

BACKGROUNDS

Hepatotoxicity due to anti tuberculosis drugs, rifampin and isoniazid, is a major problem in tuberculosis patients. Vitamin C, an antioxidant, and N-acetyl cysteine (NAC), a scavenger of active metabolites, reduce the hepatotoxicity. The aim of present study was to investigate the effect of vitamin C and NAC individually on the antibacterial activity of anti tuberculosis drugs against Mycobacterium tuberculosis and Staphylococcus aureus strains.

METHODS

The MICs of each compound against all strains were determined in 96 wells plate. Rifampin was tested at serial two fold concentrations alone or in combination with NAC or vitamin C.

RESULTS

The MIC of rifampin against different strains of S. aureus was 0.008-0.032 μg/ml. The MIC of rifampin and isoniazid against M. tuberculosis strains were 40 and 0.2 μg/ml, respectively. Vitamin C and NAC had no antibacterial activity against all strains. MIC of rifampin was reduced two fold by combination with vitamin C for all S. aureus strains, while NAC did not affect the antibacterial activity of rifampin. Vitamin C and NAC had remarkable effects on the antibacterial activity of anti-tuberculosis drugs against M. tuberculosis.

CONCLUSIONS

Synergistic effects were observed between rifampin or isoniazid and vitamin C against all tested strains. However, combination therapy of rifampin and isoniazid with NAC was not being effective. This study highlighted the advantages of combination of anti-tuberculosis drugs and vitamin C to eradicate the microbial infections.

Oncogenes and inflammation rewire host energy metabolism in the tumor microenvironment: RAS and NFκB target stromal MCT4

Here, we developed a model system to evaluate the metabolic effects of oncogene(s) on the host microenvironment. A matched set of "normal" and oncogenically transformed epithelial cell lines were co-cultured with human fibroblasts, to determine the "bystander" effects of oncogenes on stromal cells. ROS production and glucose uptake were measured by FACS analysis. In addition, expression of a panel of metabolic protein biomarkers (Caveolin-1, MCT1, and MCT4) was analyzed in parallel. Interestingly, oncogene activation in cancer cells was sufficient to induce the metabolic reprogramming of cancer-associated fibroblasts toward glycolysis, via oxidative stress. Evidence for "metabolic symbiosis" between oxidative cancer cells and glycolytic fibroblasts was provided by MCT1/4 immunostaining. As such, oncogenes drive the establishment of a stromal-epithelial "lactate-shuttle", to fuel the anabolic growth of cancer cells. Similar results were obtained with two divergent oncogenes (RAS and NFκB), indicating that ROS production and inflammation metabolically converge on the tumor stroma, driving glycolysis and upregulation of MCT4. These findings make stromal MCT4 an attractive target for new drug discovery, as MCT4 is a shared endpoint for the metabolic effects of many oncogenic stimuli. Thus, diverse oncogenes stimulate a common metabolic response in the tumor stroma. Conversely, we also show that fibroblasts protect cancer cells against oncogenic stress and senescence by reducing ROS production in tumor cells. Ras-transformed cells were also able to metabolically reprogram normal adjacent epithelia, indicating that cancer cells can use either fibroblasts or epithelial cells as "partners" for metabolic symbiosis. The antioxidant N-acetyl-cysteine (NAC) selectively halted mitochondrial biogenesis in Ras-transformed cells, but not in normal epithelia. NAC also blocked stromal induction of MCT4, indicating that NAC effectively functions as an "MCT4 inhibitor". Taken together, our data provide new strategies for achieving more effective anticancer therapy. We conclude that oncogenes enable cancer cells to behave as selfish "metabolic parasites", like foreign organisms (bacteria, fungi, viruses). Thus, we should consider treating cancer like an infectious disease, with new classes of metabolically targeted "antibiotics" to selectively starve cancer cells. Our results provide new support for the "seed and soil" hypothesis, which was first proposed in 1889 by the English surgeon, Stephen Paget.

Sub-acute administration of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate induces toxicity and oxidative stress in mice: unexpected effects of N-acetylcysteine

The organic tellurium compound (S)-dimethyl 2-(3-(phenyltellanyl) propanamide) succinate (TeAsp) exhibits thiol-peroxidase activity that could potentially offer protection against oxidative stress. However, data from the literature show that tellurium is a toxic agent to rodents. In order to mitigate such toxicity, N-acetylcysteine (NAC) was administered in parallel with TeAsp during 10 days. Mice were separated into four groups receiving daily injections of (A) vehicle (PBS 2.5 ml/kg, i.p. and DMSO 1 ml/kg, s.c.), (B) NAC (100 mg/kg, i.p. and DMSO s.c.), (C) PBS i.p. and TeAsp (92.5 μmol/kg, s.c), or (D) NAC plus TeAsp. TeAsp treatment started on the fourth day. Vehicle or NAC-treated animals showed an increase in body weight whereas TeAsp caused a significant reduction. Contrary to expected, NAC co-administration potentiated the toxic effect of TeAsp, causing a decrease in body weight. Vehicle, NAC or TeAsp did not affect the exploratory and motor activity in the open-field test at the end of the treatment, while the combination of NAC and TeAsp produced a significant decrease in these parameters. No DNA damage or alterations in cell viability were observed in leukocytes of treated animals. Treatments produced no or minor effects on the activities of antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase, whereas the activity of the thioredoxin reductase was decreased in the brain and increased the liver of the animals in the groups receiving TeAsp or TeAsp plus NAC. In conclusion, the toxicity of TeAsp was potentiated by NAC and oxidative stress appears to play a central role in this process.

Ameliorative effect of silibinin against N-nitrosodimethylamine-induced hepatic fibrosis in rats

The protective effect of silibinin (SBN) against hepatic fibrosis induced by repeated intermittent administration of N-nitrosodimethylamine (DMN) was investigated in rats. Oral administration of SBN recovered body and liver weight loss and reversed the elevation of serum AST, ALT and ALP accompanied by their fall in the liver tissue in DMN-induced fibrotic rats. Severe oxidative stress induced in fibrotic rats was evidenced by two to three fold elevation in MDA and protein carbonyl levels associated with a fall in the activities of SOD and CAT in repeated DMN treatment and this adversity was protected by SBN post-treatment. Further, the fall in the activities of ATPases and increase in the levels of hydroxyproline and collagen observed in the liver tissue of DMN treated rats was prevented and reversed back toward normalcy by SBN post-treatment. Recovery of rat liver tissue against DMN-induced hepatocellular necrosis, inflammatory changes and hepatic fibrosis by SBN treatment is also confirmed by both H & E and Masson's trichrome stained histopathological evaluation of liver tissue. In conclusion, SBN exhibit hepatoprotective, antioxidant, free radical scavenging, membrane stabilizing and anti-fibrotic activity against DMN-induced hepatic fibrosis suggesting that it may be useful as a therapeutic agent toward amelioration of hepatic fibrosis.

Impact of intravascular hemolysis in malaria on liver dysfunction: involvement of hepatic free heme overload, NF-κB activation, and neutrophil infiltration

We have investigated the impact of persistent intravascular hemolysis on liver dysfunction using the mouse malaria model. Intravascular hemolysis showed a positive correlation with liver damage along with the increased accumulation of free heme and reactive oxidants in liver. Hepatocytes overinduced heme oxygenase-1 (HO-1) to catabolize free heme in building up defense against this pro-oxidant milieu. However, in a condition of persistent free heme overload in malaria, the overactivity of HO-1 resulted in continuous transient generation of free iron to favor production of reactive oxidants as evident from 2',7'-dichlorofluorescein fluorescence studies. Electrophoretic mobility shift assay documented the activation of NF-κB, which in turn up-regulated intercellular adhesion molecule 1 as evident from chromatin immunoprecipitation studies. NF-κB activation also induced vascular cell adhesion molecule 1, keratinocyte chemoattractant, and macrophage inflammatory protein 2, which favored neutrophil extravasation and adhesion in liver. The infiltration of neutrophils correlated positively with the severity of hemolysis, and neutrophil depletion significantly prevented liver damage. The data further documented the elevation of serum TNFα in infected mice, and the treatment of anti-TNFα antibodies also significantly prevented neutrophil infiltration and liver injury. Deferoxamine, which chelates iron, interacts with free heme and bears antioxidant properties that prevented oxidative stress, NF-κB activation, neutrophil infiltration, hepatocyte apoptosis, and liver damage. Furthermore, the administration of N-acetylcysteine also prevented NF-κB activation, neutrophil infiltration, hepatocyte apoptosis, and liver damage. Thus, hepatic free heme accumulation, TNFα release, oxidative stress, and NF-κB activation established a link to favor neutrophil infiltration in inducing liver damage during hemolytic conditions in malaria.