Redox signaling and modulation in ageing.

In spite of considerable progress that has been reached in understanding how reactive oxygen species (ROS) interact with its cellular targets, several important challenges regarding regulatory effects of redox signaling mechanisms remain to be addressed enough in aging and age-related disorders. Redox signaling is precisely regulated in different tissues and subcellular locations. It modulates the homeostatic balance of many regulatory facilities such as cell cycle, circadian rhythms, adapting the external environments, etc. The newly proposed term "adaptive redox homeostasis" describes the transient increase in ROS buffering capacity in response to amplified ROS formation rate within a physiological range. Redox-dependent second messengers are generated in subcellular locations according to a specific set of rules and regulations. Their appearance depends on cellular needs in response to variations in external and internal stimulus. The intensity and magnitude of ROS signaling determines its downstream effects. This issue includes review and research papers in the context of redox signaling mechanisms and related redox-regulatory interventions, aiming to guide for understanding the degenerative processes of biological ageing and alleviating possible prevention approaches for age-related complications.

Redox signaling in impaired cascades of wound healing: promising approach.

In the aging communities, wound healing management is a quite remarkable problem especially in elderly individuals. The optimal level of healing of wounds developed spontaneously or due to surgery is of critical importance in order to prevent the negative effects that may occur due to delayed healing (for example, organ or system damage caused by infections that may develop in the wound area). The deteriorated subcellular redox signaling is considered to be as the main factor in the chronicity of wounds. The pivotal role of mitochondria in redox regulation reveals the importance of modulation of redox signaling pathways in senescent cells. Secretory factors released upon the acquisition of senescence-associated secretory phenotype (SASP) function in a paracrine manner to disseminate impaired tissue redox status by affecting the redox metabolome of nearby cells, which could promote age-related pro-inflammatory pathologies. Evaluating the wound-site redox regulation in impaired redox signaling pathways may help prevent the formation of chronic wounds and the development of long-term complications of the wounds, especially in the elderly. Using the redox modulatory pharmacologically active substances targeting the senescent cells in chronic wound areas hopefully opens a new avenue in wound management. As the signaling mechanisms of wound healing and its relationship with advanced age become more clearly understood, many promising therapeutic approaches and redox modulator substances are coming into clinical view for the management of chronic wounds.

Mitochondria-targeted senotherapeutic interventions.

Healthy aging is the art of balancing a delicate scale. On one side of the scale, there are the factors that make life difficult with aging, and on the other side are the products of human effort against these factors. The most important factors that make the life difficult with aging are age-related disorders. Developing senotherapeutic strategies may bring effective solutions for the sufferers of age-related disorders. Mitochondrial dysfunction comes first in elucidating the pathogenesis of age-related disorders and presenting appropriate treatment options. Although it has been widely accepted that mitochondrial dysfunction is a common characteristic of cellular senescence, it still remains unclear why dysfunctional mitochondria occupy a central position in the development senescence-associated secretory phenotype (SASP) related to age-related disorders. Mitochondrial dysfunction and SASP-related disease progression are closely interlinked to weaken immunity which is a common phenomenon in aging. A group of substances known as senotherapeutics targeted to senescent cells can be classified into two main groups: senolytics (kill senescent cells) and senomorphics/senostatics (suppress their SASP secretions) in order to extend health lifespan and potentially lifespan. As mitochondria are also closely related to the survival of senescent cells, using either mitochondria-targeted senolytic or redox modulator senomorphic strategies may help us to solve the complex problems with the detrimental consequences of cellular senescence. Killing of senescent cells and/or ameliorate their SASP-related negative effects are currently considered to be effective mitochondria-directed gerotherapeutic approaches for fighting against age-related disorders.

Melatonin-related signaling pathways and their regulatory effects in aging organisms.

Melatonin is a tryptophan-derived ancestral molecule evolved in bacteria. According to the endosymbiotic theory, eukaryotic cells received mitochondria, plastids, and other organelles from bacteria by internalization. After the endosymbiosis, bacteria evolved into organelles and retained their ability of producing melatonin. Melatonin is a small, evolutionarily conserved indole with multiple receptor-mediated, receptor-dependent, and independent actions. Melatonin's initial function was likely a radical scavenger in bacteria that's why there was high intensity of free radicals on primitive atmosphere in the ancient times, and hormetic functions of melatonin, which are effecting through the level of gene expression via prooxidant and antioxidant redox pathways, are developed in throughout the eukaryotic evolution. In the earlier stages of life, endosymbiotic events between mitochondria and other downstream organelles continue with mutual benefits. However, this interaction gradually deteriorates as a result of the imperfection of both mitochondrial and extramitochondrial endosymbiotic crosstalk with the advancing age of eukaryotic organisms. Throughout the aging process melatonin levels tend to reduce and as a manifestation of this, many symptoms in organisms' homeostasis, such as deterioration in adjustment of cellular clocks, are commonly seen. In addition, due to deterioration in mitochondrial integrity and functions, immunity decreases, and lower levels of melatonin renders older individuals to be more susceptible to impaired redox modulation and age-related diseases. Our aim in this paper is to focus on the several redox modulation mechanisms in which melatonin signaling has a central role, to discuss melatonin's gerontological aspects and to provide new research ideas with researchers.

Novel biomarkers for the evaluation of aging-induced proteinopathies.

Proteinopathies are characterized by aging related accumulation of misfolded protein aggregates. Irreversible covalent modifications of aging proteins may significantly affect the native three dimentional conformation of proteins, alter their function and lead to accumulation of misfolded protein as dysfunctional aggregates. Protein misfolding and accumulation of aberrant proteins are known to be associated with aging-induced proteinopathies such as amyloid ß and tau proteins in Alzheimer's disease, α-synuclein in Parkinson's disease and islet amyloid polypeptides in Type 2 diabetes mellitus. Protein oxidation processes such as S-nitrosylation, dityrosine formation and some of the newly elucidated processes such as carbamylation and citrullination recently drew the attention of researchers in the field of Gerontology. Studying over these processes and illuminating their relations between proteinopathies may help to diagnose early and even to treat age related disorders. Therefore, we have chosen to concentrate on aging-induced proteinopathic nature of these novel protein modifications in this review.

Impaired redox homeostasis in the heart left ventricles of aged rats experiencing fast-developing severe hypobaric hypoxia.

Despite its rare occurrence, humans and animals have been prone to getting fast developing severe hypobaric hypoxia. Understanding the redox homeostasis related response of an aging heart to this type of hypoxia are crucially important, since the metabolism of myocardial tissue depends on the redox status of proteins. Rodents can tolerate hypoxic stress better than human subjects. This study was aimed at investigating the effects of fast developing severe hypobaric hypoxia on redox status biomarkers; such as, advanced oxidation protein products (AOPP), lipid hydroperoxides (LHPs), protein carbonyl groups (PCO), protein thiol groups (P-SH), and total thiol groups (T-SH) on the myocardial left ventricles of young and aged Wistar rats. The rats were gradually ascended and exposed to an 8000-meter hypobaric hypoxia. While AOPP levels showed no difference, the TSH and PSH concentrations decreased, and the PCO and LHP increased in both of the hypoxic groups than the controls. The TSH and PSH were lower, and AOPP, PCO and LHP were found to be higher in the elderly hypoxic groups than in the young ones. The significant outcome of the study represents that an 8000-meter hypobaric hypoxia could be considered as a severe hypoxic stress, but not life-treating for the rats and would affect both the young and aged left ventricles similarly in respect to impaired redox status. However, if the percentage increases are taken into consideration, it seems that the higher rate of protein oxidation occurs in young hearts; meanwhile aged hearts are more prone to T-SH oxidation.

The effects of lipoic acid on redox status in brain regions and systemic circulation in streptozotocin-induced sporadic Alzheimer's disease model.

While the deterioration of insulin-glucose metabolism (IGM), impaired redox homeostasis (IRH), ß-amyloid accumulation was reported in Sporadic Alzheimer's Disease (SAD) model, aforementioned factors related to lipoic acid administration and anthropometric indexes (AIs) are not yet studied with integrative approach. ß-amyloid accumulation, redox homeostasis biomarkers and AIs are investigated in SAD model. Streptozotocin-induced inhibition of insulin-signaling cascade but not GLUT-2 and GLUT-3 transporters takes a role in ß-amyloid accumulation. Inhibition types are related to IRH in cortex, hippocampus and systemic circulation. Lipoic acid (LA) shows both antioxidant and prooxidant effect according to the anatomical location. LA administration also leads to improved AIs during GLUT-2 inhibition and cortical redox status in GLUT-3 inhibited group. Optimal LA action could be possible if its redox behavior is balanced to antioxidant effect. Diagnostic usage of systemic IRH parameters as biomarkers and their possible correlations with deteriorated IGM should be investigated. Graphical abstract ᅟ.

Gender and chronological age affect erythrocyte membrane oxidative indices in citrate phosphate dextrose adenine-formula 1 (CPDA-1) blood bank storage condition.

It is well known that in vitro storage lesions lead to membrane dysfunction and decreased number of functional erythrocytes. As erythrocytes get older, in storage media as well as in peripheral circulation, they undergo a variety of biochemical changes. In our study, the erythrocytes with different age groups in citrate phosphate dextrose adenine-formula 1 (CPDA-1) storage solution were used in order to investigate the possible effect of gender factor on oxidative damage. Oxidative damage biomarkers in erythrocyte membranes such as ferric reducing antioxidant power, pro-oxidant-antioxidant balance, protein-bound advance glycation end products, and sialic acid were analyzed. Current study reveals that change in membrane redox status during blood-bank storage condition also depends on both gender depended homeostatic factors and the presence of CPDA-1. During the storage period in CPDA-1, erythrocytes from the male donors are mostly affected by free radical-mediated oxidative stress but erythrocytes obtained from females are severely affected by glyoxidative stress.

Hyperoxic oxidative stress during abdominal surgery: a randomized trial.

PURPOSE: The hypothesis of our study is that during anesthesia, administration of 80 % oxygen concentration increases oxidative stress more than 40 % oxygen. METHODS: Forty ASA I-II patients were included in a randomized, single-blind study. Expiratory tidal volumes (ETV) were measured before induction and after extubation. After ventilation with 0.8 FiO2 and intubation, mini-bronchoalveolar lavage (mini-BAL), arterial blood gas (ABG), and blood samples were taken. Patients were randomly assigned to receive 0.8 (group I) or 0.4 (group II) FiO2 during management. Before extubation, mini-BAL, ABG, blood samples were taken. PaO2/FiO2, lactate, malondialdehyde (MDA), protein carbonyl (PCO), superoxide dismutase (SOD), total sulfhydryl (T-SH), non-protein sulfhydryl (NPSH), and protein sulfhydryl (PSH) were measured. In both groups, mean arterial pressure and heart rate values were recorded with 30-min intervals. RESULTS: ETV values were higher in group II after extubation. PaO2/FiO2 values were higher in group II after extubation compared to group I. In both groups, plasma PCO, SOD, and T-SH levels increased significantly before extubation, whereas the increase in MDA was not significant between groups. Plasma PCO, T-SH, and lactate levels were higher in group I, and plasma SOD, and PSH were higher in group I before extubation. In both groups, MDA, SOD, T-SH, and NPSH levels in mini-BAL increased significantly before extubation. Between-group comparisons, PCO, T-SH, PSH, and NPSH were significantly higher in the BAL samples of group II, and MDA levels were higher in group I. CONCLUSIONS: We found that 80 % FiO2 decreased ETV and PaO2/FiO2 and increased lactate levels and oxidative stress more, inhibiting antioxidant response compared to 40 % FiO2.

Age-related changes in rat prostate tissue; perspective of protein oxidation.

BACKGROUND: Increased systemic oxidative stress is considered as an important risk factor for prostate cancer occurrence; however, the relationship between impaired redox homeostasis of prostate tissue and aging remains unclear. OBJECTIVE: In our study, we hypothesized that age-related deterioration of redox homeostasis in prostate tissue may be considered as a predisposing factor for prostate cancer occurrence. METHODS: Sprague-Dawley rats were divided into two groups as young control (5 months) and naturally aged (24 months). We investigated the levels of oxidant and antioxidant parameters in prostate tissue. RESULTS: Advanced oxidation protein products, protein carbonyl, non-protein thiol and lipid hydroperoxides levels of aged rats were significantly higher than in the young control rats (p < 0.01, p < 0.05, p < 0.001, p < 0.05, respectively). Additionally, antioxidant activity of Cu-Zn-superoxide dismutase in elderly group was significantly lower than young controls (p < 0.05). CONCLUSIONS: We suggest that increased non-protein thiol levels found in aged rats may prevent further dissemination of oxidative protein damage. We also propose that the increased levels of oxidative protein damage markers and decreased Cu-Zn superoxide dismutase activity in aged prostate may be considered as a predisposing factor for prostate cancer. Further studies are warranted to clarify all these oxidative changes as initiation factors for prostate cancer in the association of aging with prostate cancer.

Effect of tempol on redox homeostasis and stress tolerance in mimetically aged Drosophila.

We aimed to test our hypothesis that scavenging reactive oxygen species (ROS) with tempol, a membrane permeable antioxidant, affects the type and magnitude of oxidative damage and stress tolerance through mimetic aging process in Drosophila. Drosophila colonies were randomly divided into three groups: (1) no D-galactose, no tempol; (2) D-galactose without tempol; (3) D-galactose, but with tempol. Mimetic aging was induced by d-galactose administration. The tempol-administered flies received tempol at the concentration of 0.2% in addition to d-galactose. Thiobarbituric acid reacting substance (TBARS) concentrations, advanced oxidation protein products (AOPPs), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), sialic acid (SA) were determined. Additionally, stress tolerances were tested. Mimetically aged group without tempol led to a significant decrease in tolerance to heat, cold, and starvation (P < 0.05), but tempol was used for these parameters. The Cu,Zn-SOD activity and SA concentrations were lower in both mimetically aged and tempol-administered Drosophila groups compared to control (P < 0.05), whereas there were no significantly difference between mimetically aged and tempol-administered groups. Mimetically aged group without tempol led to a significant increase in tissue TBARS and AOPPs concentrations (P < 0.05). Coadministration of tempol could prevent these alterations. Scavenging ROS using tempol also restores redox homeostasis in mimetically aged group. Tempol partly restores age-related oxidative injury and increases stress tolerance.

Aging-associated Aberrant Mitochondrial Redox Signaling, Physical Activity, and Sarcopenia.

Aging-related alteration of mitochondrial morphology, impairment in metabolic capacity, bioenergetics, and biogenesis are closely associated with loss of muscle mass and function. Mitochondrial Reactive Oxygen Species (ROS) stimulate muscular redox signaling mechanisms. Bioenergetic integrity of mitochondria and redox signaling dynamics deteriorates in aged skeletal muscle. Mitochondrial bioenergetic impairment leads to excessive ROS levels and induces the generation of defective mitochondria. Higher ROS levels may induce senescence or apoptosis. It is not a resolved issue that mitochondrial dysfunction is either the sole reason or a consequence of muscle loss (or both). However, Increasing evidence emphasizes that dysregulated mitochondrial redox signaling has a central role in age-related muscle loss. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates redox signaling pathways with the expression of antioxidant genes. As the aberrant redox signaling mechanisms in aging skeletal muscle become clearer, new natural and synthetic Nrf2-modulating substances and integrated daily physical activity alternatives are coming into view for preventing muscle loss in the elderly. A comprehensive understanding of the relationship between redox signaling pathways and age-related sarcopenia can help us to prevent sarcopenia and its frailty effects with an optimized exercise program as an innovative non-pharmacological therapeutic approach. A further aspect is necessary to consider both individualized physical training options and alternative Nrf2 signaling modulators. Ameliorating the redox signaling with physical activity and pharmacological interventions may help to prevent sarcopenia and its frailty effects.

The Role of Glycogen Synthase Kinase-3ß in the Zinc-Mediated Neuroprotective Effect of Metformin in Rats with Glutamate Neurotoxicity.

Metformin has been suggested to have protective effects on the central nervous system, but the mechanism is unknown. The similarity between the effects of metformin and the inhibition of glycogen synthase kinase (GSK)-3ß suggests that metformin may inhibit GSK-3ß. In addition, zinc is an important element that inhibits GSK-3ß by phosphorylation. In this study, we investigated whether the effects of metformin on neuroprotection and neuronal survival were mediated by zinc-dependent inhibition of GSK-3ß in rats with glutamate-induced neurotoxicity. Forty adult male rats were divided into 5 groups: control, glutamate, metformin + glutamate, zinc deficiency + glutamate, and zinc deficiency + metformin + glutamate. Zinc deficiency was induced with a zinc-poor pellet. Metformin was orally administered for 35 days. D-glutamic acid was intraperitoneally administered on the 35th day. On the 38th day, neurodegeneration was examined histopathologically, and the effects on neuronal protection and survival were evaluated via intracellular S-100ß immunohistochemical staining. The findings were examined in relation to nonphosphorylated (active) GSK-3ß levels and oxidative stress parameters in brain tissue and blood. Neurodegeneration was increased (p < 0.05) in rats fed a zinc-deficient diet. Active GSK-3ß levels were increased in groups with neurodegeneration (p < 0.01). Decreased neurodegeneration, increased neuronal survival (p < 0.01), decreased active GSK-3ß (p < 0.01) levels and oxidative stress parameters, and increased antioxidant parameters were observed in groups treated with metformin (p < 0.01). Metformin had fewer protective effects on rats fed a zinc-deficient diet. Metformin may exert neuroprotective effects and increase S-100ß-mediated neuronal survival by zinc-dependent inhibition of GSK-3ß during glutamate neurotoxicity.

Human serum albumin and its relation with oxidative stress.

Human serum albumin, a negative acute phase reactant and marker of nutritive status, presents at high concentrations in plasma. Albumin has always been used in many clinical states especially to improve circulatory failure. It has been showed that albumin is involved in many bioactive functions such as regulation of plasma osmotic pressure, binding and transport of various endogenous or exogenous compounds, and finally extracellular antioxidant defenses. Molecules like transferrin, caeruloplasmin, haptoglobin, uric acid, bilirubin, alpha-tocopherol, glucose, and albumin constitute extracellular antioxidant defenses in blood plasma but albumin is the most potent one. Most of the antioxidant properties of albumin can be attributed to its unique biochemical structure. The protein possesses antioxidant properties such as binding copper tightly and iron weakly, scavenging free radicals, e.g., hypochlorous acid (HOCl) and Peroxynitrite (ONOOH) and providing thiol group (-SH). Whether it is chronic or acute, during many pathological conditions, biomarkers of oxidative protein damage increase and this observation continues with considerable oxidation of human serum albumin. There is an important necessity to specify its interactions with Reactive Oxygen Species. Generally, it may lower the availability of pro-oxidants and be preferentially oxidized to protect other macromolecules but all these findings make it necessary that researchers give a more detailed explanation of albumin and its relations with oxidative stress.

Mitochondria-associated cellular senescence mechanisms: Biochemical and pharmacological perspectives.

Initially, endosymbiotic relation of mitochondria and other cellular compartments had been continued mutually. However, that evolutionary adaptation impaired because of the deterioration of endosymbiotic crosstalk due to aging and several pathological consequences in cellular redox status are seen, such as deterioration in redox integrity of mitochondria, interfered inter-organelle redox signaling and inefficient antioxidant response element mediated gene expression. Although the dysfunction of mitochondria is known to be a classical pattern of senescence, it is unresolved that why dysfunctional mitochondria is the core of senescence-associated secretory phenotype (SASP). Redox impairment and SASP-related disease development are generally together with weaken immunity. Impaired mitochondrial redox integrity and its ineffectiveness in immunity control render elders to be more prone to age-related diseases. As senotherapeutic agents, senolytics remove senescent cells whilst senomorphics/senostatics inhibits the secretion of SASP. Senotherapeutics and the novel approaches for ameliorating SASP-related unfavorable effects are recently thought to be promising ways as mitochondria-targeted gerotherapeutic options.

Significance of Intercellular adhesion molecule-1 Lys496Glu gene polimorphism on plasma redox status regulation in laryngeal carcinoma.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) is a surface glycoprotein important for tumor invasion and angiogenesis. The present research is conducted to investigate whether specific gene polymorphism of ICAM-1 K469E (rs5498) and plasma redox status could be associated with laryngeal cancer (LC) development. Since there is no clear evidence which investigates the relationship between ICAM-1 polymorphism and ROS-mediated plasma protein oxidation in LC, our study is the first significant contribution for investigating the relationship. METHODS: The study covered patients with primary LC and their age-matched healthy control subjects. Evaluation of ICAM-1 K469E (rs5498) gene polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism. Plasma redox status was assessed with spectrophotometric methods. RESULTS: In the current paper, we found that LC patients with GG genotype had a decreasing trend for the plasma oxidative damage biomarker levels when compared with all allele genotypes (AA and AG). CONCLUSION: We concluded that G allele of the ICAM-1 K469E gene plays a significant role in the optimal regulation of plasma redox homeostasis in patients with LC.

Comparison of oxidative stress biomarkers in renal tissues of D-galactose induced, naturally aged and young rats.

Ageing of kidneys is a clinical health issue of the society. Age-related renal insufficiency has important implications due to impaired redox homeostasis. We examined protein, DNA and lipid oxidation biomarkers as well as protein-bound sialic acid (SA) in the kidney tissues of D-galactose induced ageing rats, naturally aged rats and their corresponding young control group. Intraperitoneal injection of D-galactose (60 mg/kg/day) for 6 weeks to young male Sprague-Dawley rats (20-week-old) was used to establish mimetic ageing model. In this study, we investigated the levels of protein carbonyl groups (PCO), various thiol fractions such as total thiol groups (T-SH), protein (P-SH) and non-protein thiol groups (NP-SH), lipid oxidation parameters such as lipid hydroperoxides (LHP) and malondialdehyde (MDA), SA and 8-hydroxy-2'deoxyguanosine (8-OHdG) parameters for comparison of naturally aged, induced aged and young rats. In D-galactose induced aged group, PCO, LHP, MDA, and 8-OHdG concentrations were significantly higher than young control group, whereas T-SH, P-SH levels were significantly lower than the young rats. In addition, NP-SH and SA concentrations were similar between the mimetic ageing and young control groups. In naturally ageing rats, PCO and MDA levels were significantly higher, whereas T-SH, P-SH, NP-SH concentrations were low compared to young controls. On the other hand, SA and 8-OHdG levels were not different between the naturally ageing group and the young control group. Our results demonstrated that the rats in the mimetic ageing group, have significant similarities with the naturally aged rats in terms of impaired redox homeostasis and can be used as a reliable animal model for renal ageing.

Melatonin ameliorates oxidative damage in hyperglycemia-induced liver injury.

PURPOSE: Melatonin (N-acetyl-5-methoxy-tryptamine) is synthesized mainly by the pineal gland and its antioxidant properties have been demonstrated both in short and long term studies. Our aim was to clarify the effects of hyperglycemia and to administer melatonin on lipid peroxidation, protein oxidation and oxidative DNA damage in rat. METHODS: Malondialdehyde (MDA), protein carbonyl (PCO) and total thiol (T-SH) levels were determined in plasma and liver tissue, glutathione (GSH) levels in erythrocyte and liver tissue, and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels in plasma and liver. Thirty-eight male Wistar rats were divided into four groups: 1--injected with saline (n = 8), 2--injected with melatonin (n = 10), 3--injected with STZ (65 mg/kg, i.p.) (diabetic group) (n = 10) and 4--injected with melatonin (10 mg/kg/day, i.p.) and STZ (65 mg/kg, i.p.) (n = 10) for 8 weeks (diabetic+ melatonin group). Colorimetric methods were used to determine the level of the oxidative stress markers. 8-OhdGwas measured using ELISA. RESULTS: MDA, PCO and 8-OHdG levels in the plasma and the liver homogenates of diabetic rats were higher than controls and were significantly reduced after melatonin treatment. T-SH and GSH levels in samples were markedly reduced in untreated diabetic rats compared with control rats; however, these parameters were increased in diabetic rats following melatonin treatment. CONCLUSION: Our findings showed that melatonin administration partially ameliorated oxidative damage in liver injury in STZ-induced diabetic rats. The present study suggests that melatonin functions as a potent antioxidant agent in diabetes. Melatonin, a nutritional supplement, may be a good therapeutic option for diabetic patients.

Redox status biomarkers in the fast-twitch extensor digitorum longus resulting from the hypoxic exercise.

The fast-twitch muscle may be affected from over-produced reactive oxygen species (ROS) during hypoxia/hypoxic exercise. The study aims to investigate redox status biomarkers in the fast-twitch extensor digitorum longus (EDL) muscle after hypoxic exercise. Male Sprague Dawley rats (eight-week-old) were randomly divided into six groups of the experimental "live high train high (LHTH), live high train low (LHTL) and live low train low (LLTL)" and their respective controls. Before the EDLs' extraction, the animals exercised for a 4-week familiarization period, then they exercised for four-weeks at different altitudes. The LHTH group had higher ratios of lipid hydroperoxides (LHPs) than the experimental groups of LHTL (p=0.004) and LLTL (p=0.002), while having no difference than its control 'LH'. Similarly, a higher percentage of advanced oxidation protein products (AOPP) was determined in the LHTH than the LHTL (p=0.041) and LLTL (p=0.048). Furthermore, oxidation of thiol fractions was the lowest in the LHTH and LH. However, redox biomarkers and thiol fractions illustrated no significant change in the LHTL and LLTL that might ensure redox homeostasis due to higher oxygen consumption. The study shows that not hypoxic exercise/exercise, but hypoxia might itself lead to a redox imbalance in the fast-twitch EDL muscle.

Significance of Cyclooxgenase-2 gene polymorphism and related miRNAs in pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare disease with a poor prognosis. The suppression of cyclooxygenase-2 (COX-2) expression has been known to impair vascular function in endothelial cells; however, the epigenetic factors that cause this are largely obscure. Our aim in this study was to examine the polymorphisms in the gene for COX-2 (PTGS2) and related miRNAs regulating its level in a single-center cohort of patients with PAH. METHOD: In this study, three SNPs and miRNAs (rs5275, rs689470, rs20417, miR-26b-5p, miR-146a-5p, and miR-101-5p) in the PTGS2 were screened in PAH and controls by qPCR. In addition, the COX-2 level was determined by immunoassay to examine the effects of epigenetic factors on its expression levels. RESULTS: The non-dominant genotypes of rs20417 and rs5275 were found to be related to PAH (OR = 8.56, 95% CI = 3.39-21.63, p < 0.0001 and OR = 7.82, 95% CI = 3.30-18.53, p < 0.0001, respectively). We also observed a significant increase in the miR-26b-5p and miR-146a-5p levels in PAH patients (2.18 and 2.35-fold, respectively; for both, p < 0.05). In addition, it was found that SNPs influenced the COX-2, miR-26b-5p, and miR-146a-5p levels in PAH. A negative correlation was also found between COX-2 levels and miR-26b-5p and miR-146a-5p. CONCLUSIONS: As conventional drug therapies may cause lower COX-2 levels, the development of new genetic or epigenetic biomarkers is crucially important for early diagnosis and prognosis. The presence of minor alleles for rs5275 and rs689470 might also be considered as a significant risk factor for developing PAH. Furthermore, locus-specific miRNAs, such as miR-26b-5p and miR-146a-5p, seem to play a critical role in the regulation of PTGS2 expression.