N‑acetylcysteine induces apoptosis via the mitochondria‑dependent pathway but not via endoplasmic reticulum stress in H9c2 cells

N-acetyl Cysteine Overdose Induced Acute Toxicity and Hepatic Microvesicular Steatosis by Disrupting GSH and Interfering Lipid Metabolisms in Normal Mice

N-acetyl cysteine (NAC) is a versatile drug used in various conditions, but the limitations and toxicities are not clear. The acute toxicity and toxicological mechanisms of an intraperitoneal injection of NAC in normal mice were deciphered. The LD50 for male and female BALB/cByJNarl mice were 800 mg/kg and 933 mg/kg. The toxicological mechanisms of 800 mg/kg NAC (N800) were investigated. The serum biomarkers of hepatic and renal indices dramatically increased, followed by hepatic microvesicular steatosis, renal tubular injury and necrosis, and splenic red pulp atrophy and loss. Thus, N800 resulted in mouse mortality mainly due to acute liver, kidney, and spleen damages. The safe dose (275 mg/kg) of NAC (N275) increased hepatic antioxidant capacity by increasing glutathione levels and catalase activity. N275 elevated the hepatic gene expressions of lipid transporter, lipid synthesis, β-oxidation, and ketogenesis, suggesting a balance between lipid production and consumption, and finally, increased ATP production. In contrast, N800 increased hepatic oxidative stress by decreasing glutathione levels through suppressing Gclc, and reducing catalase activity. N800 decreased the hepatic gene expressions of lipid transporter, lipid synthesis, and interferred β-oxidation, leading to lipid accumulation and increasing Cyp2E1 expression, and finally, decreased ATP production. Therefore, NAC doses are limited for normal individuals, especially via intraperitoneal injection or similar means.

Exploring the Antiproliferative and Modulatory Effects of 1-Methoxyisobrassinin on Ovarian Cancer Cells: Insights into Cell Cycle Regulation, Apoptosis, Autophagy, and Its Interactions with NAC

Ovarian cancer, a highly lethal malignancy among reproductive organ cancers, poses a significant challenge with its high mortality rate, particularly in advanced-stage cases resistant to platinum-based chemotherapy. This study explores the potential therapeutic efficacy of 1-methoxyisobrassinin (MB-591), a derivative of indole phytoalexins found in Cruciferae family plants, on both cisplatin-sensitive (A2780) and cisplatin-resistant ovarian cancer cells (A2780 cis). The findings reveal that MB-591 exhibits an antiproliferative effect on both cell lines, with significantly increased potency against cisplatin-sensitive cells. The substance induces alterations in the distribution of the cell cycle, particularly in the S and G2/M phases, accompanied by changes in key regulatory proteins. Moreover, MB-591 triggers apoptosis in both cell lines, involving caspase-9 cleavage, PARP cleavage induction, and DNA damage, accompanied by the generation of reactive oxygen species (ROS) and mitochondrial dysfunction. Notably, the substance selectively induces autophagy in cisplatin-resistant cells, suggesting potential targeted therapeutic applications. The study further explores the interplay between MB-591 and antioxidant N-acetylcysteine (NAC), in modulating cellular processes. NAC demonstrates a protective effect against MB-591-induced cytotoxicity, affecting cell cycle distribution and apoptosis-related proteins. Additionally, NAC exhibits inhibitory effects on autophagy initiation in cisplatin-resistant cells, suggesting its potential role in overcoming resistance mechanisms.

Adaptive changes in tumor cells in response to reductive stress

Reductive stress is characterized by an excess of cellular electron donors and can be linked with various human pathologies including cancer. We developed melanoma cell lines resistant to reductive stress agents: rotenone (ROTR), n-acetyl-L-cysteine, (NACR), or dithiothreitol (DTTR). Resistant cells divided more rapidly and had intracellular homeostatic redox-couple ratios that were shifted towards the reduced state. Resistance caused alterations in general cell morphology, but only ROTR cells had significant changes in mitochondrial morphology with higher numbers that were more isolated, fragmented and swollen, with greater membrane depolarization and decreased numbers of networks. These changes were accompanied by lower basal oxygen consumption and maximal respiration rates. Whole cell flux analyses and mitochondrial function assays showed that NACR and DTTR preferentially utilized tricarboxylic acid (TCA) cycle intermediates, while ROTR used ketone body substrates such as D, L-β-hydroxybutyric acid. NACR and DTTR cells had constitutively decreased levels of reactive oxygen species (ROS), although this was accompanied by activation of nuclear factor erythroid 2-related factor 2 (Nrf2), with concomitant increased expression of the downstream gene products such as glutathione S-transferase P (GSTP). Further adaptations included enhanced expression of endoplasmic reticulum proteins controlling the unfolded protein response (UPR). Although expression patterns of these UPR proteins were distinct between the resistant cells, a trend implied that resistance to reductive stress is accompanied by a constitutively increased UPR phenotype in each line. Overall, tumor cells, although tolerant of oxidative stress, can adapt their energy and survival mechanisms in lethal reductive stress conditions.

LNS8801 inhibits Acute Myeloid Leukemia by Inducing the Production of Reactive Oxygen Species and Activating the Endoplasmic Reticulum Stress Pathway

Despite recent therapeutic advances, the 5-year survival rate for adults with acute myeloid leukemia (AML) is poor and standard-of-care chemotherapy is associated with significant toxicity, highlighting the need for new therapeutic approaches. Recent work from our group and others established that the G protein-coupled estrogen receptor (GPER) is tumor suppressive in melanoma and other solid tumors. We performed a preliminary screen of human cancer cell lines from multiple malignancies and found that LNS8801, a synthetic pharmacologic agonist of GPER currently in early phase clinical trials, promoted apoptosis in human AML cells. Using human AML cell lines and primary cells, we show that LNS8801 inhibits human AML in preclinical in vitro models, while not affecting normal mononuclear cells. Although GPER is broadly expressed in normal and malignant myeloid cells, this cancer-specific LNS8801-induced inhibition appeared to be independent of GPER signaling. LNS8801 induced AML cell death primarily through a caspase-dependent apoptosis pathway. This was independent of secreted classical death receptor ligands, and instead required induction of reactive oxygen species (ROS) and activation of endoplasmic reticulum (ER) stress response pathways including IRE1α. These studies demonstrate a novel activity of LNS8801 in AML cells and show that targeting ER stress with LNS8801 may be a useful therapeutic approach for AML.

Significance

Previous work demonstrated that LNS8801 inhibits cancer via GPER activation, especially in solid tumors. Here we show that LNS8801 inhibits AML via GPER-independent mechanisms that include ROS induction and ER activation.

Role of Klotho and N-acetylcysteine in Oxidative Stress Associated with the Vitrification of Ovarian Tissue Cytoprotective Function of Klotho in Cryopreservation

BACKGROUND

Cryopreservation can cause mechanical and chemical stress, ultimately leading to the formation of reactive oxygen species (ROS) and oxidative stress. ROS inhibits the expression of antioxidant enzymes in cells, resulting in increased DNA fragmentation and apoptosis. In this paper, we used a vitrification method that has the advantage of producing less ice crystal formation, cost-effectiveness, and time efficiency during cryopreservation. The objective of this paper is to evaluate the degree of protection of ovarian tissue against oxidative stress when N-acetylcysteine (NAC) and Klotho proteins are treated in the vitrification process of ovarian tissue.  METHODS: The control group and the cryopreservation groups were randomly assigned, and treated NAC, Klotho, or the combination (NAC + Klotho). The cell morphological change, DNA damage, senescence, and apoptosis of each group after the freeze-thaw process were compared using transmission electron microscopy, immunohistochemistry, and western blot analysis.

RESULTS

Both NAC and Klotho were found to be more effective at protecting against DNA damage than the control; however, DNA damage was greater in the NAC + Klotho group than in the group treated with NAC and Klotho, respectively. DNA damage and cellular senescence were also reduced during the vitrification process when cells were treated with NAC, Klotho, or the combination (NAC + Klotho). NAC increased apoptosis during cryopreservation, whereas Klotho inhibited apoptosis and NAC-induced apoptosis.

CONCLUSION

This study highlights Klotho's benefits in inhibiting DNA damage, cell senescence, and apoptosis, including NAC-induced apoptosis, despite its unclear role in vitrification.

Low-dose N-acetyl cysteine prevents paraquat-induced mortality in Caenorhabditis elegans

Exposure to the herbicide paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridinium dichloride) affects the redox balance of the cell, an effect that can be restored by antioxidants, including N-acetyl cysteine (NAC). One hour of exposure to PQ (0 mM, 10 mM, 50 mM, or 100 mM) dose-dependently increased mortality in Caenorhabditis elegans after exposure (immediate toxicity), while this effect was more evident 24 hours thereafter (delayed toxicity). Importantly, pretreatment with NAC 0.5 mM for one hour partially prevented mortality in the immediate assay, while it had no effect in the delayed test, revealing the importance of long-term studies when evaluating toxicity.

Blockade of p38 MAPK overcomes AML stem cell line KG1a resistance to 5-Fluorouridine and the impact on miRNA profiling

Most of the AML patients in remission develop multidrug resistance after the first-line therapy and relapse. AML stem cells have gained attention for their chemoresistance potentials. Chemoresistance is a multifactorial process resulting from altered survival signaling pathways and apoptosis regulators such as MAPK, NF-κB activation and ROS production. We targeted the survival pathway p38 MAPK, NF-κB and ROS generation in human chemoresistant AML stem cell line KG1a, susceptible to enhance cell sensitivity to the chemotherapy drug 5-Fluorouridine, compared to the chemosensitive AML cell line HL60. After confirming the phenotypic characterization of KG1a and HL60 cells using flow cytometry and transcriptomic array analyses, cell treatment with the NF-κB inhibitor IKKVII resulted in a complete induction of apoptosis, and a few p38 MAPK inhibitor SB202190-treated cells underwent apoptosis. No change in the apoptosis status was observed in the ROS scavenger N-acetylcysteine-treated cells. The p38 MAPK pathway blockade enhanced the KG1a cell sensitivity to 5-Fluorouridine, which was associated with the upregulation of microribonucleic acid-(miR-)328-3p, as determined by the microarray-based miRNA transcriptomic analysis. The downregulation of the miR-210-5p in SB202190-treated KG1a cells exposed to FUrd was monitored using RT-qPCR. The miR-328-3p is known for the enhancement of cancer cell chemosensitivity and apoptosis induction, and the downregulation of miR-210-5p is found in AML patients in complete remission. In conclusion, we highlighted the key role of the p38 MAPK survival pathway in the chemoresistance capacity of the AML stem cells and potentially involved miRNAs, which may pave the way for the development of a new therapeutic strategy targeting survival signaling proteins and reduce the rate of AML relapse.

Antitumor Activities for Two Pt(II) Complexes of Tropolone and 8-Hydroxyquinoline Derivative

The reactions of cis-Pt(DMSO)2Cl2 and tropolone (HL) with 8-hydroxyquinoline (HQ) or 2-methyl-8-hydroxyquinoline (HMQ) gave [Pt(Q)(L)] (1) and [Pt(MQ)(L)] (2), which present mononuclear structures with their Pt(II) ions four-coordinated in square planar geometries. Their in vitro biological properties were evaluated by MTT assay, which showed a remarkable cytotoxic activity on the cancer cell lines. 1 shows higher cytotoxic activities on tumor cells such as T24, HeLa, A549, and NCI-H460 than complex 2 and cisplatin, with IC50 values <16 μM. Among them, an IC50 value of 3.6 ± 0.63 μM was found for complex 1 against T24 cells. It presented a tuning cytotoxic activity by substitution groups on 8-hydroxyquinoline skeleton. In our case, the substitution groups of -H are much superior to -CH3 against tumor cells. It revealed that both complexes can induce cell apoptosis by decreasing the potential of a mitochondrial membrane, enhancing reactive oxygen species and increasing Ca2+ levels of T24 cells. The T24 cell cycle can be arrested at G2 and G1 phases by complexes 1 and 2, respectively, with an upregulation for P21 and P27 expression levels and a down-regulation for cyclin A, CDK1, Cdc25A, and cyclin B expression levels. Furthermore, complex 1 exhibits satisfactory in vivo antitumor activity as revealed by the tumor inhibitory rate and the tumor weight change as well as by the cute toxicity assay and renal pathological examinations, which is close to cisplatin and much better than complex 2. All of these suggest that 1 might be a potential candidate for developing into a safe and effective anticancer agent.

Evaluation of the Antimicrobial Efficacy of N-Acetyl-l-Cysteine, Rhamnolipids, and Usnic Acid-Novel Approaches to Fight Food-Borne Pathogens

In the food industry, the increasing antimicrobial resistance of food-borne pathogens to conventional sanitizers poses the risk of food contamination and a decrease in product quality and safety. Therefore, we explored alternative antimicrobials N-Acetyl-l-cysteine (NAC), rhamnolipids (RLs), and usnic acid (UA) as a novel approach to prevent biofilm formation and reduce existing biofilms formed by important food-borne pathogens (three strains of Salmonella enterica and two strains of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus). Their effectiveness was evaluated by determining minimum inhibitory concentrations needed for inhibition of bacterial growth, biofilm formation, metabolic activity, and biofilm reduction. Transmission electron microscopy and confocal scanning laser microscopy followed by image analysis were used to visualize and quantify the impact of tested substances on both planktonic and biofilm-associated cells. The in vitro cytotoxicity of the substances was determined as a half-maximal inhibitory concentration in five different cell lines. The results indicate relatively low cytotoxic effects of NAC in comparison to RLs and UA. In addition, NAC inhibited bacterial growth for all strains, while RLs showed overall lower inhibition and UA inhibited only the growth of Gram-positive bacteria. Even though tested substances did not remove the biofilms, NAC represents a promising tool in biofilm prevention.

Induced Cell Death as a Possible Pathway of Antimutagenic Action

The existing concepts of antimutagenesis are briefly reviewed. Published reports on antimutagenic and proapoptotic properties of some polyphenols and compounds of other chemical groups obtained in representative in vitro and in vivo experiments on eukaryotic test systems are discussed. The relationships between the antimutagenic and proapoptotic properties of the analyzed compounds (naringin, apigenin, resveratrol, curcumin, N-acetylcysteine, etc.) are considered in favor of the hypothesis on induced cell death as an antimutagenic tool.

Do Autophagy Enhancers/ROS Scavengers Alleviate Consequences of Mild Mitochondrial Dysfunction Induced in Neuronal-Derived Cells?

Mitochondrial function is at the nexus of pathways regulating synaptic-plasticity and cellular resilience. The involvement of brain mitochondrial dysfunction along with increased reactive oxygen species (ROS) levels, accumulating mtDNA mutations, and attenuated autophagy is implicated in psychiatric and neurodegenerative diseases. We have previously modeled mild mitochondrial dysfunction assumed to occur in bipolar disorder (BPD) using exposure of human neuronal cells (SH-SY5Y) to rotenone (an inhibitor of mitochondrial-respiration complex-I) for 72 and 96 h, which exhibited up- and down-regulation of mitochondrial respiration, respectively. In this study, we aimed to find out whether autophagy enhancers (lithium, trehalose, rapamycin, and resveratrol) and/or ROS scavengers [resveratrol, N-acetylcysteine (NAC), and Mn-Tbap) can ameliorate neuronal mild mitochondrial dysfunction. Only lithium (added for the last 24/48 h of the exposure to rotenone for 72/96 h, respectively) counteracted the effect of rotenone on most of the mitochondrial respiration parameters (measured as oxygen consumption rate (OCR)). Rapamycin, resveratrol, NAC, and Mn-Tbap counteracted most of rotenone's effects on OCR parameters after 72 h, possibly via different mechanisms, which are not necessarily related to their ROS scavenging and/or autophagy enhancement effects. The effect of lithium reversing rotenone's effect on OCR parameters is compatible with lithium's known positive effects on mitochondrial function and is possibly mediated via its effect on autophagy. By-and-large it may be summarized that some autophagy enhancers/ROS scavengers alleviate some rotenone-induced mild mitochondrial changes in SH-SY5Y cells.

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.

Association of heat shock protein A2 expression and sperm quality after N-acetyl-cysteine supplementation in astheno-terato-zoospermic infertile men

In infertile men, reduced expression of heat shock protein A2 (HSPA2) is related to reduced sperm quality and function. The present study has aimed to investigate the effects of N-acetyl-cysteine (NAC) supplementation on expression of heat shock protein A2 (HSPA2). In this study in continuation of previous study, semen samples from 50 astheno-terato-zoospermic men who have received NAC (600 mg/day) orally for three months were evaluated for expression HSPA2 using RT-PCR, and Western blot analysis. In addition, semen samples of these individuals were assessed for sperm parameters, DNA fragmentation (TUNEL), protamine deficiency (CMA3), lipid peroxidation index (MDA) and total antioxidant capacity (TCA). All assessment was carried out before and after NAC treatment. In addition to improved sperm parameters and aforementioned functional parameters, the presented results revealed the significant increase in relative expression levels of HSPA2 was obtained after using NAC treatment (p < .05). Correlation analysis also demonstrated that HSPA2 expression is significantly related to most of the assessed parameters. NAC may directly or indecently impose its beneficial effect through increased expression of HSPA2, which plays a potential role in proper folding of element needed to counteract stress condition in infertile individuals.

Targeting mitochondrial dysfunction with small molecules in intervertebral disc aging and degeneration

The prevalence of rheumatic and musculoskeletal diseases (RMDs) including osteoarthritis (OA) and low back pain (LBP) in aging societies present significant cost burdens to health and social care systems. Intervertebral disc (IVD) degeneration, which is characterized by disc dehydration, anatomical alterations, and extensive changes in extracellular matrix (ECM) composition, is an important contributor to LBP. IVD cell homeostasis can be disrupted by mitochondrial dysfunction. Mitochondria are the main source of energy supply in IVD cells and a major contributor to the production of reactive oxygen species (ROS). Therefore, mitochondria represent a double-edged sword in IVD cells. Mitochondrial dysfunction results in oxidative stress, cell death, and premature cell senescence, which are all implicated in IVD degeneration. Considering the importance of optimal mitochondrial function for the preservation of IVD cell homeostasis, extensive studies have been done in recent years to evaluate the efficacy of small molecules targeting mitochondrial dysfunction. In this article, we review the pathogenesis of mitochondrial dysfunction, aiming to highlight the role of small molecules and a selected number of biological growth factors that regulate mitochondrial function and maintain IVD cell homeostasis. Furthermore, molecules that target mitochondria and their mechanisms of action and potential for IVD regeneration are identified. Finally, we discuss mitophagy as a key mediator of many cellular events and the small molecules regulating its function.

Activation of NRF2 and ATF4 Signaling by the Pro-Glutathione Molecule I-152, a Co-Drug of N-Acetyl-Cysteine and Cysteamine

I-152 combines two pro-glutathione (GSH) molecules, namely N-acetyl-cysteine (NAC) and cysteamine (MEA), to improve their potency. The co-drug efficiently increases/replenishes GSH levels in vitro and in vivo; little is known about its mechanism of action. Here we demonstrate that I-152 not only supplies GSH precursors, but also activates the antioxidant kelch-like ECH-associated protein 1/nuclear factor E2-related factor 2 (KEAP1/NRF2) pathway. The mechanism involves disulfide bond formation between KEAP1 cysteine residues, NRF2 stabilization and enhanced expression of the γ-glutamil cysteine ligase regulatory subunit. Accordingly, a significant increase in GSH levels, not reproduced by treatment with NAC or MEA alone, was found. Compared to its parent compounds, I-152 delivered NAC more efficiently within cells and displayed increased reactivity to KEAP1 compared to MEA. While at all the concentrations tested, I-152 activated the NRF2 pathway; high doses caused co-activation of activating transcription factor 4 (ATF4) and ATF4-dependent gene expression through a mechanism involving Atf4 transcriptional activation rather than preferential mRNA translation. In this case, GSH levels tended to decrease over time, and a reduction in cell proliferation/survival was observed, highlighting that there is a concentration threshold which determines the transition from advantageous to adverse effects. This body of evidence provides a molecular framework for the pro-GSH activity and dose-dependent effects of I-152 and shows how synergism and cross reactivity between different thiol species could be exploited to develop more potent drugs.

Mitochonic acid 5 regulates mitofusin 2 to protect microglia

Microglial apoptosis is associated with neuroinflammation and no effective strategies are currently available to protect microglia against inflammation-induced apoptosis. Mouse microglial BV-2 cells (5 × 10⁶) were incubated with 10 μg/mL lipopolysaccharides for 12 hours to mimic an inflammatory environment. Then the cells were co-cultured with mitochonic acid 5 (MA-5) for another 12 hours. MA-5 improved the survival of lipopolysaccharide-exposed cells. MA-5 decreased the activity of caspase-3, which is associated with apoptosis. MA-5 reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells, and increased adenosine triphosphate levels in cells. MA-5 decreased the open state of the mitochondrial permeability transition pore and reduced calcium overload and diffusion of second mitochondria-derived activator of caspase (Smac). MA-5 decreased the expression of apoptosis-related proteins (mitochondrial Smac, cytoplasmic Smac, pro-caspase-3, cleaved-caspase-3, and caspase-9), and increased the levels of anti-apoptotic proteins (Bcl2 and X-linked inhibitor of apoptosis protein), mitochondria-related proteins (mitochondrial fusion protein 2, mitochondrial microtubule-associated proteins 1A/1B light chain 3B II), and autophagy-related proteins (Beclin1, p62 and autophagy related 5). However, MA-5 did not promote mitochondrial homeostasis or decrease microglial apoptosis when Mitofusin 2 expression was silenced. This shows that MA-5 increased Mitofusin 2-related mitophagy, reversed cellular energy production and maintained energy metabolism in BV-2 cells in response to lipopolysaccharide-induced inflammation. These findings indicate that MA-5 may promote the survival of microglial cells via Mitofusin 2-related mitophagy in response to lipopolysaccharide-induced inflammation.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Role of Glutathione Depletion and Reactive Oxygen Species Generation on Caspase-3 Activation: A Study With the Kinase Inhibitor Staurosporine

Oxidative stress is known to contribute to the progression of apoptosis. Staurosporine is a broad-spectrum inducer of apoptosis, but its mechanism of action is not well understood. The goal of the present work was to elucidate the role of glutathione and reactive oxygen species (ROS) in the execution of staurosporine-induced apoptosis. HeLa cells were treated with staurosporine at 1 μM for up to 4 h. The concentration of glutathione, generation of ROS, and activation of caspase-3 were measured. The introduction of staurosporine significantly decreased the concentration of cellular glutathione and increased the presence of ROS after 3 h. These findings were concurrent with the activation of caspase-3. Interestingly, pre-treatment of cells with N-acetylcysteine, a precursor of glutathione, and a thiol antioxidant failed to block the depletion of glutathione, generation of ROS, and activation of caspase-3. Collectively, these results suggest that the cellular redox status may be one of the critical factors of the apoptotic pathway leading to caspase-3 activation by staurosporine.

PTEN inhibition attenuates endothelial cell apoptosis in coronary heart disease via modulating the AMPK-CREB-Mfn2-mitophagy signaling pathway

Atherosclerosis (AS) is a major pathogenic factor in patients with cardiovascular diseases, and endothelial dysfunction (ED) plays a primary role in the occurrence and development of AS. In our study, we attempted to evaluate the role of phosphatase and tensin homolog (PTEN) in endothelial cell apoptosis under oxidized low-density lipoprotein (ox-LDL) stimulation and identify the associated mechanisms. The results of our study demonstrated that ox-LDL induced human umbilical vein endothelial cell (HUVEC) death via mitochondrial apoptosis, as evidenced by reduced mitochondrial potential, increased mitochondria permeability transition pore opening, cellular calcium overload, and caspase-9/-3 activation. In addition, ox-LDL also suppressed cellular energy production via downregulating the mitochondrial respiratory complex. Moreover, ox-LDL impaired HUVECs migration. Western blot analysis showed that PTEN expression was upregulated after exposure to ox-LDL and knockdown of PTEN could attenuate ox-LDL-mediated endothelial cell damage. Furthermore, we found that ox-LDL impaired mitophagy activity, whereas PTEN deletion could improve mitophagic flux and this effect relied on the activity of the AMP-activated protein kinase (AMPK)-cAMP-response element-binding protein (CREB)-Mitofusin-2 (Mfn2) axis. When the AMPK-CREB-Mfn2 pathway was inhibited, PTEN deletion-associated HUVECs protection was significantly reduced, suggesting that the AMPK-CREB-Mfn2-mitophagy axis is required for PTEN deletion-mediated endothelial cell survival under ox-LDL. Taken together, our results indicate that ox-LDL-induced endothelial cell damage is associated with PTEN overexpression, and inhibition of PTEN could promote endothelial survival via activating the AMPK-CREB-Mfn2-mitophagy signaling pathway.

20-hydroxyeicosatetraenoic acid alters endothelial cell barrier integrity independent of oxidative stress and cell death

Unregulated inflammation during bovine mastitis is characterized by severe mammary tissue damage with systemic involvement. Vascular dysfunction underlies tissue pathology because of concurrent oxidative stress mediated by several inflammatory mediators. We recently demonstrated increased production of 20-hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450-derived (CYP) oxylipid that correlated with oxidative stress during severe bovine coliform mastitis. The hypothesis for this study was that 20-HETE-induced oxidative stress disrupts barrier function of endothelial cells. Primary endothelial cells from the bovine aorta were utilized to investigate the effects of 20-HETE on barrier integrity in an in-vitro model of oxidative stress. The effects of various antioxidants on modulating the 20-HETE barrier integrity effects also were investigated. Our results showed that 20-HETE decreased endothelial barrier integrity, which was associated with increased reactive metabolite production and decreased total glutathione. The antioxidant, vitamin E, partially delayed the loss of endothelial resistance upon exposure to 20-HETE but did not prevent complete loss of barrier integrity. The decrease in barrier resistance due to 20-HETE was neither associated with oxidative stress as assessed by oxidative protein or lipid damage nor endothelial cell apoptosis; however, selenium supplementation conferred resistance to loss of barrier integrity suggesting a role for shifts in redox status. Specific mechanisms by which 20-HETE alters vascular barrier integrity require further investigation to identify targets for therapy during inflammatory conditions with enhanced CYP450 activity.

Optimal Regimen of N-Acetylcysteine on Chromium-Induced Renal Cell Damage

Chromium (Cr) is a well-known heavy metal that can cause renal damage. The production of reactive oxygen species (ROS) due to chromium-induced toxicity induces cell dysfunction, apoptosis, and death. N-acetylcysteine (NAC) is an antioxidant used as an antidote for chromium-induced toxicity. However, the optimal regimen and protective mechanisms of NAC are not fully understood in human renal cells. Our results showed that exposure to 10 μM K₂Cr₂O₇, a toxic Cr(VI) compound, induced apoptosis and production of intracellular ROS in the human proximal tubular epithelial cell line HK-2. Supplements of 600 or 1000 µg/mL NAC inhibited intracellular ROS in HK-2 cells exposed to Cr(VI) and significantly increased cell viability within 2 h of Cr(VI)-induced cytotoxicity. Moreover, Cr(VI) induced the expression of apoptosis markers, including cleaved-caspase-3, cleaved-poly (ADP-ribose) polymerase, cleaved-caspase 8, and cleaved-caspase 9, and altered the expression ratio of Bax/Bcl-xL. Expression of apoptosis markers within 2 h of Cr(VI)-induced cytotoxicity in cells treated with 600 µg/mL NAC was significantly suppressed. However, delayed treatment with NAC at 4 h and 8 h after exposure to Cr did not suppress the activation of apoptotic pathways. In summary, our study reports the optimum timing and dose of NAC for the protection of human renal proximal tubular cells from Cr(VI)-induced cell death. The NAC treatment strategy described could be applied in clinical practice to suppress renal cell apoptosis, which in turn could rescue renal function.

Therapeutic effect of N- acetyl cysteine as an antioxidant on rainbow trout's brain in cypermethrin toxicity

The aim of this study was to investigate the therapeutic effect of N-acetylcystein (NAC) against oxidative stress induced by Cypermethrin pesticide in rainbow trout (Oncorhynchus mykiss). The experiment was designed as 5 groups (A, B, C, D, and E). Group A was organized as control group and had no treatment. The other groups were treated with Cypermethrin for 14 days. At the end of this period, Groups B (1.0 mM NAC) and D (0.5 mM NAC) was performed with NAC for 96 h. Group C was not administered NAC, the recovery process was evaluated with this group. Group E was exposed to cypermethrin during 14 days and sampled. Acetylcholinesterase (AChE), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO) activities, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG)), caspase-3 levels, and trace elements contents analyses were performed in all fish brains. According to the results, MDA, MPO, 8-OHdG and caspase-3 levels were significantly decreased compared to the other groups (pesticide and recovery) (p < 0.05), AChE, SOD, CAT, GPx, PON, and AR activities increased (p < 0.05). In brain tissue, no statistically significant difference was observed in trace element analysis of all application groups. According to the obtained data, the positive effect of N-acetylcysteine on protein synthesis, detoxification, and diverse metabolic functions against cypermethrin toxicity has been more effective in 1.0 mM NAC. NAC has important therapeutic effect on pesticide-induced neurotoxicity for fish in terms of all data. It was concluded that NAC has an antioxidant effect against pesticide-induced oxidative stress and the selected biochemical markers are useful for such studies.