Nitrative Stress Research Articles

SCIATIC DENERVATION-INDUCED SKELETAL MUSCLE ATROPHY IS ASSOCIATED WITH PERSISTENT INFLAMMATION AND INCREASED MORTALITY DURING SEPSIS.

Background: Patients with underlying skeletal muscle atrophy are likely to develop aggravated sepsis. However, no study has experimentally verified the association between the prognosis of sepsis and muscle atrophy, and the mechanism of aggravation of sepsis under muscle atrophy remains unclear. In this study, we investigated the effect of skeletal muscle atrophy induced by sciatic denervation (DN), an experimental muscle atrophy model, on sepsis prognosis. Methods: Skeletal muscle atrophy was induced by DN of the sciatic nerve in C57BL/6J male mice. Cecal ligation and puncture (CLP) was performed to induce sepsis. Results: The survival rates of the sham and DN groups 7 days after CLP were 63% and 35%, respectively, wherein an approximately 30% reduction was observed in the DN group ( P < 0.05, vs. sham-CLP). The DN group had a higher bacterial count in the blood 48 h after CLP ( P < 0.05, vs. sham-CLP). Notably, NOx (a metabolite of nitric oxide) concentrations in DN mice were higher than those in sham mice after CLP ( P < 0.05, vs. sham-CLP), whereas serum platelet levels were lower 48 h after CLP ( P < 0.05, vs. sham-CLP). In organ damage analysis, DN mice presented increased protein expression of the kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), a kidney injury marker, after CLP (NGAL 48 h after CLP, P < 0.05, vs. sham-CLP; KIM-1 24 h after CLP, P < 0.01, vs. sham-CLP). Furthermore, nitro tyrosine levels in the kidneys of DN mice were higher 48 h after CLP compared with those in sham-CLP mice, indicating the accumulation of nitrative stress ( P < 0.05, vs. sham-CLP). Serum cytokine levels were increased in both groups after CLP, but decreased in the sham group 48 h after CLP and remained consistently higher in the DN group (tumor necrosis factor [TNF]-α: P < 0.05, sham-CLP vs. DN-CLP; interleukin (IL)-1β: P < 0.01, sham-CLP vs. DN-CLP; IL-6: P < 0.05, DN vs. DN-CLP; IL-10: P < 0.05, sham-CLP vs. DN-CLP). Conclusions: We verified that skeletal muscle atrophy induced by DN is associated with poor prognosis after CLP-induced sepsis. Importantly, mice with skeletal muscle atrophy presented worsening sepsis prognosis at late onset, including prolonged infection, persistent inflammation, and kidney damage accumulation, resulting in delayed recovery.

Hibiscetin attenuates oxidative, nitrative stress and neuroinflammation via suppression of TNF-α signaling in rotenone induced parkinsonism in rats

Parkinson's disease (PD) is the gradual and selective degradation of dopamine-releasing neurons in substantia nigra pars compacta (SNpc) and results in postural instability, stiffness, bradykinesia, and resting tremor. The goal of this research was to see how hibiscetin action on PD in rotenone-treated rats. Rats were administered orally with hibiscetin (10 mg/kg) after 1 h rotenone (0.5 mg/kg, s.c.). This therapy regimen was followed on a daily basis for 28 days.Rats were tested for catalepsy and akinesia on day 29 after the last dosage of rotenone. Biochemical parameters were performed to measure reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), nitrite, neuroinflammatory cytokines, and neurotransmitter and their metabolite levels such as dopamine (DA), norepinephrine (NE), serotonin (5-HT), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA). Rotenone-induced akinesia and catatonia in rats decreased endogenous antioxidant (GSH, CAT, and SOD) levels, increased MDA and nitrite levels, and changed neurotransmitter and metabolite levels. Hibiscetin effectively reduced rotenone-induced akinesia and catatonia, improved endogenous antioxidant (GSH, CAT and SOD) levels, and reduced oxidative and nitrative stress in the treated rats. Moreover, hibiscetin restored altered neurotransmitters and their metabolites to normal levels in rotenone-treated rats. The study results showed that hibiscetin has anti-Parkinson's activity against rotenone-induced PD in rats.

Neuroprotective effect of butin against rotenone-induced Parkinson’s disease mediated by antioxidant and anti-inflammatory actions through paraoxonase-1-induction

This investigation aimed to assess the anti-Parkinson's effect of butin in rotenone-treated rats. A total of 24 albino Wistar rats were segregated into four groups equally as follows: Group I (normal) and Group II (rotenone control); Group III and Group IV; were butin 25 and 50 mg/kg/p.o. Daily, 1 h post offer mentioned treatments, Group I animals were injected with sunflower oil (s.c.), and Group II-IV were treated subcutaneously with 2 mg/kg rotenone emulsion in sunflower oil for 28 days. On day 29, i.e. 24 h after the rotenone dose, animals were evaluated for behavioural and biochemical parameters i.e. acetylcholine-esterase, paraoxonase-1, butyrylcholinesterase, endogenous antioxidants (Glutathione, catalase, superoxide-dismutase), oxidative, nitrative stress and proinflammatory markers (Interleukin-6, IL-1β, and TNF-α). Butin attenuated the rotenone-induced catalepsy, akinesia, memory loss and decreased learning ability. Butin treatment shows rotenone-induced neurobehavioral impairments, oxidative and nitrative stress, and neuroinflammatory markers reversed the enzyme activities towards normal.

Photobiomodulation therapy protects red blood cells against nitrative stress during streptozotocin-induced diabetes

Background. According to the International Diabetes Federation Diabetes Atlas, 10th edition, diabetes is responsible for 6.7 million deaths in 2021. Diabetes mellitus is a group of metabolic disorders characterized by hyperglycemia secondary to either resistance to insulin, insufficient insulin secretion, or both. Oxidative and nitrative stress is a vital part of the complex mechanism by which diabetes and its complications develop. It is known that Photobiomodulation therapy accelerates diabetic wound healing, treats relegated inflammation, and increases oxygen availability for cells. Although some basic molecular mechanisms caused by photobiomodulation therapy in different cell types are already known, they have not been studied in erythrocytes and are different due to the absence of central organelles such as nucleus and mitochondria. The aim of the study was to investigate the effect of photobiomodulation therapy on the development of nitrative stress in blood plasma and erythrocytes of rats from different experimental groups. Materials and Methods. The study was performed on white outbred male rats weighing 130–180 g. The diabetes mellitus was induced by intraperitoneal injection of streptozotocin (60 mg/kg). Rats were exposed to photobiomodulation with light-emitting diodes at a wavelength of 630–660 nm daily for 10 days. The irradiation time was 5 minu­tes. The content of nitrite and nitrate anions, total NO synthase activity, as well as the activity of its endothelial and inducible isoforms in red blood cells of rats were determined spectrophotometrically. Results and Discussion. Under streptozotocin-induced diabetes mellitus, the content of nitrite and nitrate anions and NO synthase activity increased in the rats’ red blood cells, as well as in blood plasma. Moreover, we found an increase in inducible NO synthase activity and nitrate ion content in red blood cells of irradiated healthy rats. Also, there was an increase in nitrite and nitrate ion content after photobiomodulation therapy in the blood plasma of healthy animals. On the other hand, irradiation caused a decrease in NO synthase activity with a parallel reduction in both nitrite and nitrate anions content in erythrocytes and blood plasma of rats with experimental diabetes. Conclusion. Photobiomodulation therapy protects rats’ red blood cells from nitrative stress during streptozotocin-induced diabetes mellitus.

Oxymatrine Alleviates Gentamicin-Induced Renal Injury in Rats.

Gentamicin is an aminoglycoside antibiotic commonly used to treat Gram-negative bacterial infections that possesses considerable nephrotoxicity. Oxymatrine is a phytochemical with the ability to counter gentamicin toxicity. We investigated the effects and protective mechanism of oxymatrine in rats. The experimental groups were as follows: Control, Oxymatrine only group (100 mg/kg/d), Gentamicin only group (100 mg/kg/d), Gentamicin (100 mg/kg/d) plus Oxymatrine (100 mg/kg/d) group (n = 10). All rats were treated for seven continuous days. The results indicated that oxymatrine alleviated gentamicin-induced kidney injury, and decreased rats’ kidney indices and NAG (N-acetyl-beta-d-glucosaminidase), BUN (blood urea nitrogen) and CRE (creatine) serum levels. The oxymatrine-treated group sustained less histological damage. Oxymatrine also relived gentamicin-induced oxidative and nitrative stress, indicated by the increased SOD (superoxidase dismutase), GSH (glutathione) and CAT (catalase) activities and decreased MDA (malondialdehyde), iNOS (inducible nitric oxide synthase) and NO (nitric oxide) levels. Caspase-9 and -3 activities were also decreased in the oxymatrine-treated group. Oxymatrine exhibited a potent anti-inflammatory effect on gentamicin-induced kidney injury, down-regulated the Bcl-2ax and NF-κB mRNAs, and upregulated Bcl-2, HO-1 and Nrf2 mRNAs in the kidney tissue. Our investigation revealed the renal protective effect of oxymatrine in gentamicin-induced kidney injury for the first time. The effect was achieved through activation of the Nrf2/HO-1 pathways. The study underlines the potential clinical application of oxymatrine as a renal protectant agent for gentamicin therapy.

Rosiridin Attenuates Scopolamine-Induced Cognitive Impairments in Rats via Inhibition of Oxidative and Nitrative Stress Leaded Caspase-3/9 and TNF-α Signaling Pathways.

Aim: A monoterpene and bioactive component of the plant Rhodiola rosea (R. rosea), rosiridin has beneficial effects on the human central nervous system and enhances brain function. The goal of this scientific study was to determine if rosiridin might shield rats from neurocognitive problems induced by scopolamine. Methods: To track the potential toxicities in rats, the acute toxicity in rats was clarified. Rosiridin at a dose of 10 mg/kg was tested in rats for 14 days. At the conclusion of the investigation, behavioral parameters that were used to identify the rats’ cognitive and motor abilities were evaluated. Several biochemical parameters were estimated using the prepared homogenate, including acetylcholine esterase (AChE), choline acetyltransferase (ChAT), radical scavengers produced by the body (Catalase-CAT, superoxide dismutase-SOD, and reduced glutathione-GSH), indicators of oxidative and nitrative burnout, pro-inflammatory (Interleukins- IL-1β, IL-6, interferon gamma IFN-ꝩ, and tumor necrosis factor-TNF-α), and cell apoptosis caspases 3 and 9. Results and Conclusion: A significant behavioral parameter restoration was seen in the rosiridin-treated group, including reduction in latency time during acquisition and retention trial in the Morris water maze test, and percentage of spontaneous alterations in the y-maze test, when compared to the disease control group that received scopolamine; rosiridin also altered the oxidative stress and neuroinflammatory markers, as well as restoring Ach and ChAT activities and normalizing GSH, SOD, MDA, TNF-α, nitrate, IL-1β, IL-6, IFN-ꝩ, caspases 3 and 9 levels. The results imply that rosiridin limits the effect of scopolamine on rat cognitive function.

Coadministration of Stigmasterol and Dexamethasone (STIG+DEX) Modulates Steroid-Resistant Asthma

Airway inflammation in asthma is managed with anti-inflammatory steroids such as dexamethasone (DEX). However, about 20% of asthmatics do not respond to this therapy and are classified as steroid-resistant. Currently, no effective therapy is available for steroid-resistant asthma. This work therefore evaluated the effect of a plant sterol, stigmasterol (STIG), and stigmasterol-dexamethasone combination (STIG+DEX) in LPS-ovalbumin-induced steroid-resistant asthma in Guinea pigs. To do this, the effect of drugs on inflammatory features such as airway hyperreactivity and histopathology of lung tissue was evaluated. Additionally, the possible pathway of drug action was assessed by measuring events such neutrophil levels, oxidative and nitrative stress, and histone deacetylase 2 (HDAC2) and interleukin 17 (IL-17) levels. STIG alone did not affect inflammatory features, although it caused some changes in the molecular events associated with steroid-resistant asthma. However, STIG+DEX caused significant modulation of inflammatory features by protecting against destruction of lung tissue. The modulation of inflammatory features was associated with significant inhibition of neutrophilia and oxidative and nitrative stress, decrease in HDAC2, and increase in IL-17 levels that are usually associated with steroid-resistant asthma. Our findings show that although STIG and DEX individually do not protect against steroid-resistant asthma, their coadministration results in significant modulation of inflammatory features and the associated molecular events that lead to steroid-resistant asthma.

Lead exposure induces nitrative stress and disrupts ribbon synapses in the cochlea.

Environmental exposure to heavy metal lead, a public health hazard in many post-industrial cities, causes hearing impairment upon long-term exposure. Lead-induced cochlear and vestibular dysfunction is well-documented in animal models. Although short-term exposure to lead at concentrations relevant to environmental settings does not cause significant shifts in hearing thresholds in adults, moderate- to low-level lead exposures induce neuronal damage and synaptic dysfunction. We reported that lead exposure induces oxidative stress in the mouse cochlea. However, lead-induced nitrative stress and potential damage to cochlear ribbon synapses are yet to be fully understood. Therefore, this study has evaluated cochlear synaptopathy and nitrative stress in young-adult mice exposed to 2 mM lead acetate for 28 days. Inductively coupled plasma mass spectrometry (ICP-MS) analysis indicated that this exposure significantly increased the blood lead levels. Assessment of hair cell loss by immunohistochemistry analysis and outer hair cell (OHC) activity by recording distortion product otoacoustic emissions (DPOAEs) indicated that the structure and function of the hair cells were not affected by lead exposure. However, this exposure significantly decreased the expression of C-terminal-binding protein-2 (CtBP2) and GluA2, pre- and post-synaptic protein markers in the inner hair cell synapses, particularly in the basal turn of the organ of Corti, suggesting lead-induced disruption of ribbon synapses. In addition, lead exposure significantly increased the nitrotyrosine levels in spiral ganglion cells, suggesting lead-induced nitrative stress in the cochlea. Collectively, these findings suggest that lead exposure even at levels that do not affect the OHCs induces cochlear nitrative stress and causes cochlear synaptopathy.

Platanosides, a Potential Botanical Drug Combination, Decrease Liver Injury Caused by Acetaminophen Overdose in Mice.

Oxidative stress plays an important role in acetaminophen (APAP)-induced hepatotoxicity. Platanosides (PTSs) isolated from the American sycamore tree (Platanus occidentalis) represent a potential new four-molecule botanical drug class of antibiotics active against drug-resistant infectious disease. Preliminary studies have suggested that PTSs are safe and well tolerated and have antioxidant properties. The potential utility of PTSs in decreasing APAP hepatotoxicity in mice in addition to an assessment of their potential with APAP for the control of infectious diseases along with pain and pyrexia associated with a bacterial infection was investigated. On PTS treatment in mice, serum alanine aminotransferase (ALT) release, hepatic centrilobular necrosis, and 4-hydroxynonenal (4-HNE) were markedly decreased. In addition, inducible nitric oxide synthase (iNOS) expression and c-Jun-N-terminal kinase (JNK) activation decreased when mice overdosed with APAP were treated with PTSs. Computational studies suggested that PTSs may act as JNK-1/2 and Keap1-Nrf2 inhibitors and that the isomeric mixture could provide greater efficacy than the individual molecules. Overall, PTSs represent promising botanical drugs for hepatoprotection and drug-resistant bacterial infections and are effective in protecting against APAP-related hepatotoxicity, which decreases liver necrosis and inflammation, iNOS expression, and oxidative and nitrative stresses, possibly by preventing persistent JNK activation.

Endothelial PHD2 deficiency induces nitrative stress via suppression of caveolin-1 in pulmonary hypertension.

Nitrative stress is a characteristic feature of the pathology of human pulmonary arterial hypertension. However, the role of nitrative stress in the pathogenesis of obliterative vascular remodelling and severe pulmonary arterial hypertension remains largely unclear. Our recently identified novel mouse model (Egln1Tie2Cre, Egln1 encoding prolyl hydroxylase 2 (PHD2)) has obliterative vascular remodelling and right heart failure, making it an excellent model to use in this study to examine the role of nitrative stress in obliterative vascular remodelling. Nitrative stress was markedly elevated whereas endothelial caveolin-1 (Cav1) expression was suppressed in the lungs of Egln1Tie2Cre mice. Treatment with a superoxide dismutase mimetic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride or endothelial Nos3 knockdown using endothelial cell-targeted nanoparticle delivery of CRISPR-Cas9/guide RNA plasmid DNA inhibited obliterative pulmonary vascular remodelling and attenuated severe pulmonary hypertension in Egln1Tie2Cre mice. Genetic restoration of Cav1 expression in Egln1Tie2Cre mice normalised nitrative stress, reduced pulmonary hypertension and improved right heart function. These data suggest that suppression of Cav1 expression secondary to PHD2 deficiency augments nitrative stress through endothelial nitric oxide synthase activation, which contributes to obliterative vascular remodelling and severe pulmonary hypertension. Thus, a reactive oxygen/nitrogen species scavenger might have therapeutic potential for the inhibition of obliterative vascular remodelling and severe pulmonary arterial hypertension.

In vivo imaging of heart failure with preserved ejection fraction by simultaneous monitoring of cardiac nitric oxide and glutathione using a three-channel fluorescent probe

The pathophysiology of heart failure with preserved ejection fraction (HFpEF) remains unclear, making the diagnosis and treatment challenging. Cardiac oxidative and nitrative stress are strongly implicated in the pathogenesis of HFpEF. Herein, we present a unique three-channel fluorescent probe for evaluating cardiac oxidative and nitrative stress in HFpEF by simultaneous detection of NO and GSH. The probe exhibits a native green fluorescence (probe channel), while the presence of GSH and NO can sensitively turn the native green fluorescence into red fluorescence (GSH channel) and near-infrared fluorescence (NO channel), respectively. The probe clearly reveals that both GSH and NO levels are upregulated in cardiomyocytes and heart tissue with HFpEF. Moreover, it uncovers that the enhancement in NO and GSH levels are closely associated with increased level of iNOS (inducible nitric oxide synthase) and activation of the Keap1 (Kelch-like ECH-associated protein 1)/Nrf2 (nuclear factor erythroid 2–related factor 2)/ARE (antioxidant response element) signaling pathway in cardiomyocytes, respectively. This work proposes a promising approach for distinguishing normal heart and HFpEF heart by in vivo noninvasive imaging of both GSH and NO, and greatly contributing to the improvement of the diagnosis and treatment of HFpEF.

Variation of genes encoding nitric oxide synthases and antioxidant enzymes as potential risks of multiple sclerosis development: a preliminary study

Multiple sclerosis (MS) is a neurodegenerative disease characterized by a variable clinical course and diverse pathophysiology, including nitrative and oxidative stresses as well as inflammation. We aimed to detect the potential association between five selected single-nucleotide polymorphisms (SNPs) in genes encoding nitric oxide synthetases as well as antioxidant enzymes and the development of MS in a Polish population. Genomic DNA was isolated from peripheral blood collected from 142 MS patients and 140 controls. Using Taq-Man® probes, we genotyped the following SNPs: rs1879417 in NOS1, and rs2297518 in NOS2 as well as rs4880 in SOD2, rs7943316 in CAT, rs713041 in GPX4. In the case of rs2297518, the C/C genotype and C allele SNP were associated with an enhanced occurrence of MS, while the C/T, T/T genotypes, and T allele of the same polymorphism reduced this risk. Moreover, the C/C homozygote and C allele of the rs4880 SNP reduced MS risk, while the T allele increased the risk. In addition, the A/T heterozygote of rs7943316 polymorphism was associated with an increased risk of MS occurrence. We also detected that the C/C genotype and C allele of rs713041 decreased the risk of MS, whereas the T/T genotype and T allele increased this risk. In conclusion, the results of our study suggest some links between polymorphic variability in the nitrative/oxidative stress-related genes and the risk of MS development in the Polish population.

GLP-1 receptor nitration contributes to loss of brain pericyte function in a mouse model of diabetes.

We have previously shown that diabetes causes pericyte dysfunction, leading to loss of vascular integrity and vascular cognitive impairment and dementia (VCID). Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs), used in managing type 2 diabetes mellitus, improve the cognitive function of diabetic individuals beyond glycaemic control, yet the mechanism is not fully understood. In the present study, we hypothesise that GLP-1 RAs improve VCID by preventing diabetes-induced pericyte dysfunction. Mice with streptozotocin-induced diabetes and non-diabetic control mice received either saline (NaCl 154 mmol/l) or exendin-4, a GLP-1 RA, through an osmotic pump over 28 days. Vascular integrity was assessed by measuring cerebrovascular neovascularisation indices (vascular density, tortuosity and branching density). Cognitive function was evaluated with Barnes maze and Morris water maze. Human brain microvascular pericytes (HBMPCs), were grown in high glucose (25 mmol/l) and sodium palmitate (200 μmol/l) to mimic diabetic conditions. HBMPCs were treated with/without exendin-4 and assessed for nitrative and oxidative stress, and angiogenic and blood-brain barrier functions. Diabetic mice treated with exendin-4 showed a significant reduction in all cerebral pathological neovascularisation indices and an improved blood-brain barrier (p<0.05). The vascular protective effects were accompanied by significant improvement in the learning and memory functions of diabetic mice compared with control mice (p<0.05). Our results showed that HBMPCs expressed the GLP-1 receptor. Diabetes increased GLP-1 receptor expression and receptor nitration in HBMPCs. Stimulation of HBMPCs with exendin-4 under diabetic conditions decreased diabetes-induced vascular inflammation and oxidative stress, and restored pericyte function (p<0.05). This study provides novel evidence that brain pericytes express the GLP-1 receptor, which is nitrated under diabetic conditions. GLP-1 receptor activation improves brain pericyte function resulting in restoration of vascular integrity and BBB functions in diabetes. Furthermore, the GLP-1 RA exendin-4 alleviates diabetes-induced cognitive impairment in mice. Restoration of pericyte function in diabetes represents a novel therapeutic target for diabetes-induced cerebrovascular microangiopathy and VCID.

AORTIC REACTIVITY IN VITAMIN D DEFICIENCY IN A RAT MODEL OF POLYCYSTIC OVARY SYNDROME

Objective: Polycystic ovary syndrome (PCOS) and vitamin D deficiency are associated with elevated cardiovascular risk, whereas vitamin D deficiency is a common comorbidity in PCOS that may contribute to the pathogenesis and complications of the disease. Our aim was to investigate the role of vitamin D status on the aortic function of hyperandrogenic female rats showing the symptoms of PCOS. Design and method: Female Wistar rats received an 8-week-long transdermal Androgel treatment to induce hyperandrogenism, another group remained untreated. Half of each group was fed with vitamin D reduced rat chow, while the other half received normal chow with further supplementation of vitamin D. Norepinephrine-induced contraction, acetylcholine, insulin, and estrogen-induced relaxation of thoracic aortae was examined by wire myography. Elastic fiber density was evaluated on resorcin-fuchsin stained tissue sections. Estrogen receptor alpha, endothelial nitric oxide synthase (eNOS), and cyclooxygenase 2 (COX-2) density and protein tyrosine nitration (NT) was measured by immunohistochemistry. Results: There was no difference in the norepinephrine-induced contraction of the aortas between experimental groups. Reduced acetylcholine-, insulin- and estrogen-evoked relaxation was observed in vitamin D deficient groups. A lower level of resorcin-fuchsin staining and elevated 3- nitrotyrosine immunostaining was observed in non-hyperandrogenic vitamin D deficient rats. eNOS staining intensity was reduced by vitamin D deficiency, while COX-2 density was increased by testosterone treatment. Estrogen receptor alpha density was increased by testosterone treatment but reduced by vitamin D deficiency. Conclusions: We demonstrated an early endothelial dysfunction in a rat model of vitamin D deficient polycystic ovary syndrome. Vitamin D supplementation could prevent vascular damage. On the other hand, vitamin D deficiency itself led to decreased endothelium-dependent relaxation and increased nitrative stress. Vitamin D deficiency also led to decreased estrogen receptor alpha and eNOS density independently from hyperandrogenism. Vitamin D deficiency found in approximately 80% of PCOS women may have a significant role in the development of vascular dysfunction and may contribute to their increased cardiovascular risk.

Nitrative Stress and Auditory Dysfunction.

Nitrative stress is increasingly recognized as a critical mediator of apoptotic cell death in many pathological conditions. The accumulation of nitric oxide along with superoxide radicals leads to the generation of peroxynitrite that can eventually result in the nitration of susceptible proteins. Nitrotyrosine is widely used as a biomarker of nitrative stress and indicates oxidative damage to proteins. Ototoxic insults, such as exposure to noise and ototoxic drugs, enhance the generation of 3-nitrotyrosine in different cell types in the cochlea. Nitrated proteins can disrupt critical signaling pathways and eventually lead to apoptosis and loss of sensory receptor cells in the cochlea. Accumulating evidence shows that selective targeting of nitrative stress attenuates cellular damage. Anti-nitrative compounds, such as peroxynitrite decomposition catalysts and inducible nitric oxide synthase inhibitors, prevent nitrative stress-mediated auditory damage. However, the role of nitrative stress in acquired hearing loss and its potential significance as a promising interventional target is yet to be fully characterized. This review provides an overview of nitrative stress mechanisms, the induction of nitrative stress in the auditory tissue after ototoxic insults, and the therapeutic value of targeting nitrative stress for mitigating auditory dysfunction.

Plum Prevents Intestinal and Hepatic Inflammation in the Acute and Chronic Models of Dextran Sulfate Sodium-Induced Mouse Colitis.

Inflammatory bowel disease (IBD), including ulcerative colitis (UC), is a chronic recurrent inflammatory disease of the digestive tract and increases the risk of colon cancer. This study evaluates the effects of dietary intervention with freeze-dried plum (FDP), a natural antioxidant and anti-inflammatory fruit with no toxicity on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in a mouse model and studies the molecular mechanisms of protection through the gut-liver axis. The results show that FDP decreases the levels of inflammatory mediators, which is a nitrative stress biomarker in both acute and chronic models. FDP markedly reduces DSS-induced injury to the colonic epithelium in both acute and chronic models. In addition, FDP significantly decreases the levels of pro-oxidant markers such as CYP2E1, iNOS, and nitrated proteins (detected by anti-3-NT antibody) in DSS-induced acute and chronic colonic injury models. Furthermore, FDP markedly reduces markers of liver injury such as serum ALT/AST, antioxidant markers, and inflammatory mediators in DSS-induced acute and chronic colonic injury. These results demonstrate that the FDP exhibits a protective effect on DSS-induced acute and chronic colonic and liver injury through the gut-liver axis via antioxidant and anti-inflammatory properties.

Role of cannabinoids and the endocannabinoid system in modulation of diabetic cardiomyopathy

Diabetic complications, chiefly seen in long-term situations, are persistently deleterious to a large extent, requiring multi-factorial risk reduction strategies beyond glycemic control. Diabetic cardiomyopathy is one of the most common deleterious diabetic complications, being the leading cause of mortality among diabetic patients. The mechanisms of diabetic cardiomyopathy are multi-factorial, involving increased oxidative stress, accumulation of advanced glycation end products (AGEs), activation of various pro-inflammatory and cell death signaling pathways, and changes in the composition of extracellular matrix with enhanced cardiac fibrosis. The novel lipid signaling system, the endocannabinoid system, has been implicated in the pathogenesis of diabetes and its complications through its two main receptors: Cannabinoid receptor type 1 and cannabinoid receptor type 2, alongside other components. However, the role of the endocannabinoid system in diabetic cardiomyopathy has not been fully investigated. This review aims to elucidate the possible mechanisms through which cannabinoids and the endocannabinoid system could interact with the pathogenesis and the development of diabetic cardiomyopathy. These mechanisms include oxidative/ nitrative stress, inflammation, accumulation of AGEs, cardiac remodeling, and autophagy. A better understanding of the role of cannabinoids and the endocannabinoid system in diabetic cardiomyopathy may provide novel strategies to manipulate such a serious diabetic complication.

Magnesium sulfate restores AQP9 expression and function in human trophoblast exposed to nitrative stress

Magnesium sulfate restores AQP9 expression and function in human trophoblast exposed to nitrative stress

AGEomics Biomarkers and Machine Learning-Realizing the Potential of Protein Glycation in Clinical Diagnostics.

Protein damage by glycation, oxidation and nitration is a continuous process in the physiological system caused by reactive metabolites associated with dicarbonyl stress, oxidative stress and nitrative stress, respectively. The term AGEomics is defined as multiplexed quantitation of spontaneous modification of proteins damage and other usually low-level modifications associated with a change of structure and function—for example, citrullination and transglutamination. The method of quantitation is stable isotopic dilution analysis liquid chromatography—tandem mass spectrometry (LC-MS/MS). This provides robust quantitation of normal and damaged or modified amino acids concurrently. AGEomics biomarkers have been used in diagnostic algorithms using machine learning methods. In this review, I describe the utility of AGEomics biomarkers and provide evidence why these are close to the phenotype of a condition or disease compared to other metabolites and metabolomic approaches and how to train and test algorithms for clinical diagnostic and screening applications with high accuracy, sensitivity and specificity using machine learning approaches.

Manganese induces S-nitrosylation of PINK1 leading to nerve cell damage by repressing PINK1/Parkin-mediated mitophagy

Chronic exposure to excess manganese (Mn) causes neurotoxicity, which is characterized by Parkinson-like symptoms and referred to as manganism. In the last few decades, mitochondrial damage and subsequent energy failure have been reported to be important mechanisms of Mn toxicity, yet how Mn causes mitochondrial damage remains largely unknown. Here, we demonstrated that Mn induced S-nitrosation of phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1), a master regulator in the mitophagy pathway, results in dysregulation of mitophagy and nerve cell injury in the rat striatum. We cultured primary neurons and used 1400 W, a potent and selective inducible nitric oxide synthase (iNOS) inhibitor, as an intervention to verify the precise mechanism of Mn-induced dysregulation of mitophagy. We demonstrated that Mn-induced S-nitrosylation of PINK1 decreased the phosphorylated level of parkin RBR E3 ubiquitin-protein ligase (Parkin), as well as the translocation of Parkin to damaged mitochondria, which led to the accumulation of damaged mitochondria and mitochondrial-mediated apoptosis. Our findings indicated the unusual connection between nitrative stress and mitochondrial dysfunction in Mn-induced neurotoxicity. These data highlight the role of S-nitrosation of PINK1 in Mn-induced dysregulation of mitophagy and provide a reliable target for the development of specific drugs and the early treatment of manganism, which has important theoretical and practical significance.