Gender differences in brain susceptibility to oxidative stress are mediated by levels of paraoxonase-2 expression

Sex-specific associations of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in patients with drug-naïve schizophrenia

This present study aimed to investigate the sex-specific association of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in drug-naïve schizophrenia patients for the first time. A total of 204 participants in this study, including 137 drug-naïve schizophrenia (DNS) patients and 67 healthy controls (HCs). All participants completed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB), and were collected fasting venous blood for NGAL measurement. DNS patients also complete the Positive and Negative Syndrome Scale (PANSS). Partial correlation analysis and multiple linear regression were used to explore sex-specific associations between NGAL and cognition. All dimensions of MCCB scores were significantly lower in both male and female DNS patients than HCs. Sex differences were significant in cognitive performance in both DNS patients and HCs. Female DNS patients experienced poorer working memory and reason& problem solving than male patients. Female HCs performed a better attention/vigilance and visual learning, a poorer reason& problem solving than male HCs. In patients with DNS, NGAL levels were negatively associated with positive subscale of PANSS and positively associated with working memory and visual learning only in female. However, there was no significant correlation between NGAL levels and all cognitive tests in both male and female HCs. Regression model showed that higher level of NGAL was an independent protective factor for cognitive performance in female patients with DNS, whereas there was no such role in male patients. Our findings suggest sex specificity between NGAL levels and cognitive performance in DNS patients.

Brain extended and closed forms glutathione levels decrease with age and extended glutathione is associated with visuospatial memory

During aging, the brain is subject to greater oxidative stress (OS), which is thought to play a critical role in cognitive impairment. Glutathione (GSH), as a major antioxidant in the brain, can be used to combat OS. However, how brain GSH levels vary with age and their associations with cognitive function is unclear. In this study, we combined point-resolved spectroscopy and edited spectroscopy sequences to investigate extended and closed forms GSH levels in the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and occipital cortex (OC) of 276 healthy participants (extended form, 166 females, age range 20-70 years) and 15 healthy participants (closed form, 7 females, age range 26-56 years), and examined their relationships with age and cognitive function. The results revealed decreased extended form GSH levels with age in the PCC among 276 participants. Notably, the timecourse of extended form GSH level changes in the PCC and ACC differed between males and females. Additionally, positive correlations were observed between extended form GSH levels in the PCC and OC and visuospatial memory. Additionally, a decreased trend of closed form GSH levels with age was also observed in the PCC among 15 participants. Taken together, these findings enhance our understanding of the brain both closed and extended form GSH time course during normal aging and associations with sex and memory, which is an essential first step for understanding the neurochemical underpinnings of healthy aging.

Age-associated sex difference in the expression of mitochondria-based redox sensitive proteins and effect of pioglitazone in nonhuman primate brain

BACKGROUND

Paraoxonase 2 (PON2) and neuronal uncoupling proteins (UCP4 and UCP5) possess antioxidant, anti-apoptotic activities and minimize accumulation of reactive oxygen species in mitochondria. While age and sex are risk factors for several disorders that are linked with oxidative stress, no study has explored the age- and sex-dependent expression of PON2 isoforms, UCP4 and UCP5 in primate brain or identified a drug to activate UCP4 and UCP5 in vivo. Preclinical studies suggest that the peroxisome proliferator-activated receptor gamma agonist, pioglitazone (PIO), can be neuroprotective, although the mechanism responsible is unclear. Our previous studies demonstrated that pioglitazone activates PON2 in primate brain and we hypothesized that pioglitazone also induces UCP4/5. This study was designed to elucidate the age- and sex-dependent expression of PON2 isoforms, UCP4 and UCP5, in addition to examining the impact of systemic PIO treatment on UCP4 and UCP5 expression in primate brain.

METHODS

Western blot technique was used to determine the age- and sex-dependent expression of UCP4 and UCP5 in substantia nigra and striatum of African green monkeys. In addition, we tested the impact of daily oral pioglitazone (5 mg/kg/day) or vehicle for 1 or 3 weeks on expression of UCP4 and UCP5 in substantia nigra and striatum in adult male monkeys. PIO levels in plasma and cerebrospinal fluid (CSF) were determined using LC-MS.

RESULTS

We found no sex-based difference in the expression of PON2 isoforms, UCP4 and UCP5 in striatum and substantia nigra of young monkeys. However, we discovered that adult female monkeys exhibit greater expression of PON2 isoforms than males in substantia nigra and striatum. Our data also revealed that adult male monkeys exhibit greater expression of UCP4 and UCP5 than females in substantia nigra but not in striatum. PIO increased UCP4 and UCP5 expression in substantia nigra and striatum at 1 week, but after 3 weeks of treatment this activation had subsided.

CONCLUSIONS

Our findings demonstrate a sex-, age- and region-dependent profile to the expression of PON2, UCP4 and UCP5. These data establish a biochemical link between PPARγ, PON2, UCP4 and UCP5 in primate brain and demonstrate that PON2, UCP4 and UCP5 can be pharmacologically stimulated in vivo, revealing a novel mechanism for observed pioglitazone-induced neuroprotection. We anticipate that these outcomes will contribute to the development of novel neuroprotective treatments for Parkinson's disease and other CNS disorders.

Sex-specific effects in how childhood exposures to multiple ambient air pollutants affect white matter microstructure development across early adolescence

Ambient air pollution is ubiquitous, yet questions remain as to how it might impact the developing brain. Large changes occur in the brain's white matter (WM) microstructure across adolescence, with noticeable differences in WM integrity in male and female youth. Here we report sex-stratified effects of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) on longitudinal patterns of WM microstructure from 9-13 years-old in 8,182 (49% female) participants using restriction spectrum imaging. After adjusting for key sociodemographic factors, multi-pollutant, sex-stratified models showed that one-year annual exposure to PM2.5 and NO2 was associated with higher, while O3 was associated with lower, intracellular diffusion at age 9. All three pollutants also affected trajectories of WM maturation from 9-13 years-old, with some sex-specific differences in the number and anatomical locations of tracts showing altered trajectories of intracellular diffusion. Concentrations were well-below current U.S. standards, suggesting exposure to these criteria pollutants during adolescence may have long-term consequences on brain development.

Sex and Brain: The Role of Sex Chromosomes and Hormones in Brain Development and Parkinson's Disease

Sex hormones and genes on the sex chromosomes are not only key factors in the regulation of sexual differentiation and reproduction but they are also deeply involved in brain homeostasis. Their action is crucial for the development of the brain, which presents different characteristics depending on the sex of individuals. The role of these players in the brain is fundamental in the maintenance of brain function during adulthood as well, thus being important also with respect to age-related neurodegenerative diseases. In this review, we explore the role of biological sex in the development of the brain and analyze its impact on the predisposition toward and the progression of neurodegenerative diseases. In particular, we focus on Parkinson's disease, a neurodegenerative disorder that has a higher incidence in the male population. We report how sex hormones and genes encoded by the sex chromosomes could protect from the disease or alternatively predispose toward its development. We finally underline the importance of considering sex when studying brain physiology and pathology in cellular and animal models in order to better understand disease etiology and develop novel tailored therapeutic strategies.

Associations of Particulate Matter Exposures With Brain Gray Matter Thickness and White Matter Hyperintensities: Effect Modification by Low-Grade Chronic Inflammation

BACKGROUND

Numerous studies have shown the effect of particulate matter exposure on brain imaging markers. However, little evidence exists about whether the effect differs by the level of low-grade chronic systemic inflammation. We investigated whether the level of c-reactive protein (CRP, a marker of systemic inflammation) modifies the associations of particulate matter exposures with brain cortical gray matter thickness and white matter hyperintensities (WMH).

METHODS

We conducted a cross-sectional study of baseline data from a prospective cohort study including adults with no dementia or stroke. Long-term concentrations of particulate matter ≤ 10 µm in diameter (PM10) and ≤ 2.5 µm (PM2.5) at each participant's home address were estimated. Global cortical thickness (n = 874) and WMH volumes (n = 397) were estimated from brain magnetic resonance images. We built linear and logistic regression models for cortical thickness and WMH volumes (higher versus lower than median), respectively. Significance of difference in the association between the CRP group (higher versus lower than median) was expressed as P for interaction.

RESULTS

Particulate matter exposures were significantly associated with a reduced global cortical thickness only in the higher CRP group among men (P for interaction = 0.015 for PM10 and 0.006 for PM2.5). A 10 μg/m³ increase in PM10 was associated with the higher volumes of total WMH (odds ratio, 1.78; 95% confidence interval, 1.07-2.97) and periventricular WMH (2.00; 1.20-3.33). A 1 μg/m³ increase in PM2.5 was associated with the higher volume of periventricular WMH (odds ratio, 1.66; 95% confidence interval, 1.08-2.56). These associations did not significantly differ by the level of high sensitivity CRP.

CONCLUSION

Particulate matter exposures were associated with a reduced global cortical thickness in men with a high level of chronic inflammation. Men with a high level of chronic inflammation may be susceptible to cortical atrophy attributable to particulate matter exposures.

Paraoxonases at the Heart of Neurological Disorders

Paraoxonase enzymes serve as an important physiological redox system that participates in the protection against cellular injury caused by oxidative stress. The PON enzymes family consists of three members (PON-1, PON-2, and PON-3) that share a similar structure and location as a cluster on human chromosome 7. These enzymes exhibit anti-inflammatory and antioxidant properties with well-described roles in preventing cardiovascular disease. Perturbations in PON enzyme levels and their activity have also been linked with the development and progression of many neurological disorders and neurodegenerative diseases. The current review summarizes the available evidence on the role of PONs in these diseases and their ability to modify risk factors for neurological disorders. We present the current findings on the role of PONs in Alzheimer's disease, Parkinson's disease, and other neurodegenerative and neurological diseases.

Neuroprotective Effect of Vitamin D on Behavioral and Oxidative Parameters of Male and Female Adult Wistar Rats Exposed to Mancozeb (manganese/zinc ethylene bis-dithiocarbamate)

The constant exposure of rural workers to pesticides is a serious public health problem. Mancozeb (MZ) is a pesticide  linked to hormonal, behavioral, genetic, and neurodegenerative effects, mainly related to oxidative stress. Vitamin D is a promising molecule that acts as a protector against brain aging. This study aimed to evaluate the neuroprotective role of vitamin D in adult male and female Wistar rats exposed to MZ. Animals received 40 mg/kg of MZ i.p. and 12.5 μg/kg or 25 μg/kg vitamin D by gavage, twice a week, for 6 weeks. The concentration of manganese had a significant increase in the hippocampus of both sexes and in the striatum of females, unlike zinc, which did not show a significant increase. MZ poisoning led to mitochondrial changes in brain tissues and promoted anxiogenic effects, especially in females. Alterations in antioxidant enzymes, mainly in the catalase activity were observed in intoxicated rats. Taken together, our results showed that exposure to MZ leads to the accumulation of manganese in brain tissues, and the behavior and metabolic/oxidative impairment were different between the sexes. Furthermore, the administration of Vitamin D was effective in preventing the damage caused by the pesticide.

Ambient air pollution exposure and depressive symptoms: Findings from the French CONSTANCES cohort

BACKGROUND AND AIM

Few studies have reported the association between air pollution exposure with different dimensions of depression. We aimed to explore this association across different dimensions of depressive symptoms in a large population.

METHODS

Data from the enrollment phase of the French CONSTANCES cohort (2012-2020) were analyzed cross-sectionally. Annual concentrations of particulate matter with a diameter < 2.5 µm (PM_2.5), black carbon (BC), and nitrogen dioxide (NO₂) from the land-use regression models were assigned to the residential addresses of participants. Total depressive symptoms and its four dimensions (depressed affect, disturbed interpersonal relations, low positive affect, somatic complaints) were measured using Centre of Epidemiologic Studies Depression questionnaire (CES-D). We reported results of negative binomial regression models (reported as Incidence Rate Ratio (IRR) and 95 % confidence interval (CI) for an interquartile range (IQR) increase in exposure), for each pollutant separately. Stratified analyses were performed by sex, income, family status, education, and neighborhood deprivation.

RESULTS

The study included 123,754 participants (mean age, 46.50 ± 13.61 years; 52.4 % women). The mean concentration of PM_2.5, BC and NO₂ were 17.14 µg/m³ (IQR = 4.89), 1.82 10^-5/m (IQR = 0.88) and 26.58 µg/m³ (IQR = 17.41) respectively. Exposures to PM_2.5, BC and NO₂ were significantly associated with a higher CES-D total (IRR = 1.022; 95 % CI = 1.002: 1.042, IRR = 1.027; 95 % CI = 1.013: 1.040, and IRR = 1.029; 95 % CI = 1.015: 1.042 respectively), and with depressed affect, and somatic complaints. For all pollutants, a higher estimate was observed for depressed affect. We found stronger adverse associations for men, lower-income participants, low and middle education groups, those living in highly deprived areas, and single participants.

CONCLUSION

Our finding could assist the exploration of the etiological pathway of air pollution on depression and also considering primary prevention strategies in the areas with air pollution.

APOE alleles are associated with sex-specific structural differences in brain regions affected in Alzheimer's disease and related dementia

Alzheimer's disease is marked by intracellular tau aggregates in the medial temporal lobe (MTL) and extracellular amyloid aggregates in the default network (DN). Here, we examined codependent structural variations between the MTL's most vulnerable structure, the hippocampus (HC), and the DN at subregion resolution in individuals with Alzheimer's disease and related dementia (ADRD). By leveraging the power of the approximately 40,000 participants of the UK Biobank cohort, we assessed impacts from the protective APOE ɛ2 and the deleterious APOE ɛ4 Alzheimer's disease alleles on these structural relationships. We demonstrate ɛ2 and ɛ4 genotype effects on the inter-individual expression of HC-DN co-variation structural patterns at the population level. Across these HC-DN signatures, recurrent deviations in the CA1, CA2/3, molecular layer, fornix's fimbria, and their cortical partners related to ADRD risk. Analyses of the rich phenotypic profiles in the UK Biobank cohort further revealed male-specific HC-DN associations with air pollution and female-specific associations with cardiovascular traits. We also showed that APOE ɛ2/2 interacts preferentially with HC-DN co-variation patterns in estimating social lifestyle in males and physical activity in females. Our structural, genetic, and phenotypic analyses in this large epidemiological cohort reinvigorate the often-neglected interplay between APOE ɛ2 dosage and sex and link APOE alleles to inter-individual brain structural differences indicative of ADRD familial risk.

A photo-oxidation driven proximity labeling strategy enables profiling of mitochondrial proteome dynamics in living cells

Mapping the proteomic landscape of mitochondria with spatiotemporal precision plays a pivotal role in elucidating the delicate biological functions and complex relationship with other organelles in a variety of dynamic physiological processes which necessitates efficient and controllable chemical tools. We herein report a photo-oxidation driven proximity labeling strategy to profile the mitochondrial proteome by light dependence in living cells with high spatiotemporal resolution. Taking advantage of organelle-localizable organic photoactivated probes generating reactive species and nucleophilic substrates for proximal protein oxidation and trapping, mitochondrial proteins were selectively labeled by spatially limited reactions in their native environment. Integration of photo-oxidation driven proximity labeling and quantitative proteomics facilitated the plotting of the mitochondrial proteome in which up to 310 mitochondrial proteins were identified with a specificity of 64% in HeLa cells. Furthermore, mitochondrial proteome dynamics was deciphered in drug resistant Huh7 and LPS stimulated HMC3 cells which were hard-to-transfect. A number of differential proteins were quantified which were intimately linked to critical processes and provided insights into the related molecular mechanisms of drug resistance and neuroinflammation in the perspective of mitochondria. The photo-oxidation driven proximity labeling strategy offers solid technical support to a highly precise proteomic platform in time and finer space for more knowledge of subcellular biology.

Examining the role of paraoxonase 2 in the dopaminergic system of the mouse brain

BACKGROUND

Paraoxonase 2 (PON2) is an intracellular antioxidant enzyme located at the inner mitochondrial membrane. Previous studies have found PON2 to be an important antioxidant in a variety of cellular systems, such as the cardiovascular and renal system. Recent work has also suggested that PON2 plays an important role in the central nervous system (CNS), as decreased PON2 expression in the CNS leads to higher oxidative stress and subsequent cell toxicity. However, the precise role of PON2 in the CNS is still largely unknown, and what role it may play in specific regions of the brain remains unexamined. Dopamine metabolism generates considerable oxidative stress and antioxidant function is critical to the survival of dopaminergic neurons, providing a potential mechanism for PON2 in the dopaminergic system.

METHODS

In this study, we investigated the role of PON2 in the dopaminergic system of the mouse brain by comparing transcript and protein expression of dopaminergic-related genes in wildtype (WT) and PON2 deficient (PON2-def) mouse striatum, and exposing WT cultured primary neurons to dopamine receptor agonists.

RESULTS

We found alterations in multiple key dopaminergic genes at the transcript level, however many of these changes were not observed at the protein level. In cultured neurons, PON2 mRNA and protein were increased upon exposure to quinpirole, a dopamine receptor 2/3 (DRD2/3) agonist, but not fenoldopam, a dopamine receptor 1/5 (DRD1/5) agonist, suggesting a receptor-specific role in dopamine signaling.

CONCLUSIONS

Our findings suggest PON2 deficiency significantly impacts the dopaminergic system at the transcript level and may play a role in mitigating oxidative stress in this system further downstream through dopamine receptor signaling.

An Antioxidant and Anti-ER Stress Combo Therapy Decreases Inflammation, Secondary Brain Damage and Promotes Neurological Recovery following Traumatic Brain Injury in Mice

The complex pathophysiology of post-traumatic brain damage might need a polypharmacological strategy with a combination of drugs that target multiple, synergistic mechanisms. We currently tested a combination of apocynin (curtails formation of reactive oxygen species), tert-butylhydroquinone (promotes disposal of reactive oxygen species), and salubrinal (prevents endoplasmic reticulum stress) following a moderate traumatic brain injury (TBI) induced by controlled cortical impact in adult mice. Adult mice of both sexes treated with the above tri-combo showed alleviated motor and cognitive deficits, attenuated secondary lesion volume, and decreased oxidative DNA damage. Concomitantly, tri-combo treatment regulated post-TBI inflammatory response by decreasing the infiltration of T cells and neutrophils and activation of microglia in both sexes. Interestingly, sexual dimorphism was seen in the case of TBI-induced microgliosis and infiltration of macrophages in the tri-combo-treated mice. Moreover, the tri-combo treatment prevented TBI-induced white matter volume loss in both sexes. The beneficial effects of tri-combo treatment were long-lasting and were also seen in aged mice. Thus, the present study supports the tri-combo treatment to curtail oxidative stress and endoplasmic reticulum stress concomitantly as a therapeutic strategy to improve TBI outcomes.SIGNIFICANCE STATEMENT Of the several mechanisms that contribute to TBI pathophysiology, oxidative stress, endoplasmic reticulum stress, and inflammation play a major role. The present study shows the therapeutic potential of a combination of apocynin, tert-butylhydroquinone, and salubrinal to prevent oxidative stress and endoplasmic reticulum stress and the interrelated inflammatory response in mice subjected to TBI. The beneficial effects of the tri-combo include alleviation of TBI-induced motor and cognitive deficits and lesion volume. The neuroprotective effects of the tri-combo are also linked to its ability to prevent TBI-induced white matter damage. Importantly, neuroprotection by the tri-combo treatment was observed to be not dependent on sex or age. Our data demonstrate that a polypharmacological strategy is efficacious after TBI.

The role of sex and ovarian hormones in hippocampal damage and cognitive deficits induced by chronic exposure to hypobaric hypoxia

Purpose

This study aims to investigate the role of sex and ovarian hormones in hippocampal damage and cognitive deficits and behavioral dysfunction in rats induced by chronic exposure to hypobaric hypoxia.

Methods

Six-week-old male and female SD rats were housed for 3 months either in a real altitude (4,250 m) environment as the model of chronic hypobaric-hypoxia (CHH) or in a plain as controls. The animal behavioral and hippocampal neurons at subcellular, molecular, and ultrastructural levels were characterized after CHH exposure.

Results

After 3 months of CHH exposure, (1) male CHH rats’ serum testosterone level was lower than male controls’ whereas female CHH rats’ serum estradiol level was higher than female controls’; (2) Morris water maze test finds that male rats showed more learning and spatial memory deficits than female rats; (3) male rats showed more severe hippocampal damage, hippocampal inflammation, oxidative stress and decreased hippocampal integrity (neurogenesis and dendritic spine density) than female rats; (4) Western blot analysis shows that, compared with the male control group, in male CHH group’s hippocampus, expression of nNOS, HO-1, and Bax protein increased whereas that of Bcl-2 protein decreased; (5) Expression of PON2 protein in male rats (CHH and controls) was lower than female rats (CHH and controls). In addition, CHH exposure decreased the expression of PON2 protein in both male and female rats; (6) qPCR analysis reveals that CHH exposure reduced the gene expression of N-methyl-D-aspartate receptor NR2A and NR2B subunits in male rats’ hippocampus. In addition, compared with the sham CHH group, the expression level of PON2 protein decreased in the OVX-CHH group’s hippocampus whereas oxidative stress, neuroinflammation, and degeneration of hippocampal neurons increased in the OVX-CHH group’s hippocampus.

Conclusion

After CHH exposure, male rats were significantly more likely than female rats to develop hippocampal damage, hippocampal neuroinflammation, and cognitive decline and deficits, suggesting that sex and ovarian hormones were significantly involved in regulating the rats’ susceptibility to CHH exposure-induced hippocampal damage.

Airway epithelial Paraoxonase-2 in obese asthma

Background

Obesity in asthmatics has been associated with higher airway oxidative stress in which dysfunctional mitochondria are a potential contributing source of excess free radicals. Paraoxonase 2 (PON2) plays an important role in reducing mitochondrial-derived oxidative stress and could, therefore, have therapeutic potential in these patients.

Objectives

We used primary human bronchial epithelial cells (HBECs) from asthmatics and healthy controls to evaluate: a) protein levels of Paraoxonase 2 and b) to test the potential protective effect of quercetin supplementation in cells under oxidative stress conditions.

Results

Compared to lean controls, obese asthmatics had significantly lower PON2 airway epithelial levels (respectively, 1.08 vs. 0.47 relative units normalized by GAPDH) (p-value < 0.006). Treating HBECs in vitro for 24 hrs. with 25μM quercetin significantly increased PON2 protein levels: 15.5 treated cells vs. 9.8 untreated cells (relative units normalized by GAPDH) (p value = 0.004). Notably, compared to untreated cells, quercetin supplementation reduces mitochondrial superoxide and hydrogen peroxide production on HBECs cells exposed to different oxidative stress triggers such as 1–2 Naphthoquinone (1–2 NQ) and hydrogen peroxide, suggesting that PON2 might play a protective role ameliorating oxidative injury on human airway epithelium.

Conclusion

Compared to lean controls, obese asthmatics have significantly reduced PON2 levels in airway epithelial cells. Treatment with quercetin in vitro increased PON2 protein levels and prevented oxidative stress from different types of stimuli. Hence, quercetin supplementation may be a potential therapeutic strategy to prevent obesity-mediated airway oxidative stress in obese asthmatics.

Evaluation of Gender Differences in Response to Photobiomodulation Therapy, Including Laser Acupuncture: A Narrative Review and Implication to Precision Medicine

Background: The influence of gender is significant in the manifestation and response to many diseases and in the treatment strategy. Photobiomodulation (PBM) therapy, including laser acupuncture, is an evidence-based treatment and disease prevention modality that has shown promising efficacy for a myriad of chronic and acute diseases. Anecdotal experience and limited clinical trials suggest gender differences exist in treatment outcomes to PBM therapy. There is preliminary evidence that gender may be as important as skin color in the individual response to PBM therapy. Purpose: To conduct a literature search of publications addressing the effects of gender differences in PBM therapy, including laser acupuncture, to provide a narrative review of the findings, and to explore potential mechanisms for the influence of gender. Methods: A narrative review of the literature on gender differences in PBM applications was conducted using key words relating to PBM therapy and gender. Results: A total of 13 articles were identified. Of these articles, 11 have direct experimental investigations into the response difference in gender for PBM, including laser acupuncture. A variety of cadaver, human, and experimental studies demonstrated results that gender effects were significant in PBM outcome responses, including differences in tendon structural and mechanical outcomes, and mitochondrial gene expression. One cadaver experiment showed that gender was more important than skin tone. The physiologic mechanisms directing gender differences are explored and postulated. Conclusions: The review suggests that to address the requirements of a proficient precision medicine-based strategy, it is important for PBM therapy to consider gender in its treatment plan and dosing prescription. Further research is warranted to determine the correct dose for optimal gender treatment, including gender-specific treatment plans to improve outcomes, taking into account wavelength, energy exposure, intensity, and parameters related to the deliverance of treatment to each anatomical location.

Insights into the role of paraoxonase 2 in human pathophysiology

Paraoxonase 2 (PON2) is a ubiquitously expressed intracellular enzyme that is known to have a protective role from oxidative stress. Clinical studies have also demonstrated the significance of PON2 in the manifestation of cardiovascular and several other diseases, and hence, it is considered an important biomarker. Recent findings of its expression in brain tissue suggest its potential protective effect on oxidative stress and neuroinflammation. Polymorphisms of PON2 in humans are a risk factor in many pathological conditions, suggesting a possible mechanism of its anti-oxidative property probably through lactonase activity. However, exogenous factors may also modulate the expression and activity of PON2. Hence, this review aims to report the mechanism by which PON2 expression is regulated and its role in oxidative stress disorders such as neurodegeneration and tumor formation. The role of PON2 owing to its lactonase activity in bacterial infectious diseases and association of PON2 polymorphism with pathological conditions are also highlighted.

Insights into the role of paraoxonase 2 in human pathophysiology

Paraoxonase 2 (PON2) is a ubiquitously expressed intracellular enzyme that is known to have a protective role from oxidative stress. Clinical studies have also demonstrated the significance of PON2 in the manifestation of cardiovascular and several other diseases, and hence, it is considered an important biomarker. Recent findings of its expression in brain tissue suggest its potential protective effect on oxidative stress and neuroinflammation. Polymorphisms of PON2 in humans are a risk factor in many pathological conditions, suggesting a possible mechanism of its anti-oxidative property probably through lactonase activity. However, exogenous factors may also modulate the expression and activity of PON2. Hence, this review aims to report the mechanism by which PON2 expression is regulated and its role in oxidative stress disorders such as neurodegeneration and tumor formation. The role of PON2 owing to its lactonase activity in bacterial infectious diseases and association of PON2 polymorphism with pathological conditions are also highlighted.

Expression of PON2 isoforms varies among brain regions in male and female African green monkeys

Mitochondrial dysfunction and oxidative stress contribute to the neuropathology of neurodegenerative disorders such as Parkinson's disease (PD). Paraoxonase-2 (PON2) is a mitochondrial protein that mitigates oxidative stress, enhances mitochondrial function and exhibits anti-inflammatory properties. Previously, we have documented sex-based variation in PON2 with higher brain PON2 expression in female (2-fold) as compared to male African green monkeys. This aim of this study is to identify PON2 isoforms and explore the region-based variations in the protein level of PON2 in brain of African green monkeys. Male and female brain tissue samples (striatum, hippocampus, occipital cortex, dorsolateral prefrontal cortex) from African green monkeys (Chlorocebus sabaeus) were analyzed by western blotting technique for PON2 expression. We found two PON2 isoforms (39 and 41 kDa) in each examined brain region of male and female monkeys. Male monkeys showed no significant difference in the expression level of PON2 isoforms among different brain regions whereas female monkeys showed a significant difference in the expression level of PON2 isoforms in all examined regions except dorsolateral prefrontal cortex. In addition, the result revealed highest expression of PON2 protein in striatum compared to other brain regions in both male and female monkeys. This report is the first to quantify expression of PON2 isoforms in different brain regions and it also establishes the existence of sex as well as region-based variation in PON2 protein expression in primate brain. Since PON2 serves a protective role for dopaminergic neurons it should be considered as a druggable target for oxidative stress-related neurodegenerative disorders like PD. We anticipate that the outcome of this study will contribute to the development of neuroprotective strategies in PD.

Sex-Specific MicroRNAs in Neurovascular Units in Ischemic Stroke

Accumulating evidence pinpoints sex differences in stroke incidence, etiology and outcome. Therefore, more understanding of the sex-specific mechanisms that lead to ischemic stroke and aggravation of secondary damage after stroke is needed. Our current mechanistic understanding of cerebral ischemia states that endothelial quiescence in neurovascular units (NVUs) is a major physiological parameter affecting the cellular response to neuron, astrocyte and vascular smooth muscle cell (VSMC) injury. Although a hallmark of the response to injury in these cells is transcriptional activation, noncoding RNAs such as microRNAs exhibit cell-type and context dependent regulation of gene expression at the post-transcriptional level. This review assesses whether sex-specific microRNA expression (either derived from X-chromosome loci following incomplete X-chromosome inactivation or regulated by estrogen in their biogenesis) in these cells controls NVU quiescence, and as such, could differentiate stroke pathophysiology in women compared to men. Their adverse expression was found to decrease tight junction affinity in endothelial cells and activate VSMC proliferation, while their regulation of paracrine astrocyte signaling was shown to neutralize sex-specific apoptotic pathways in neurons. As such, these microRNAs have cell type-specific functions in astrocytes and vascular cells which act on one another, thereby affecting the cell viability of neurons. Furthermore, these microRNAs display actual and potential clinical implications as diagnostic and prognostic biomarkers in ischemic stroke and in predicting therapeutic response to antiplatelet therapy. In conclusion, this review improves the current mechanistic understanding of the molecular mechanisms leading to ischemic stroke in women and highlights the clinical promise of sex-specific microRNAs as novel diagnostic biomarkers for (silent) ischemic stroke.

Sex difference in the interrelationship between TNF-α and oxidative stress status in first-episode drug-naïve schizophrenia

Background

Increasing evidence indicates that dysregulated TNF-α and oxidative stress (OxS) contribute to the pathophysiology of schizophrenia. Additionally, previous evidence has demonstrated sex differences in many aspects of schizophrenia including clinical characteristics, cytokines, and OxS markers. However, to the best of our knowledge, there is no study investigating sex differences in the association between TNF-α, the OxS system, and their interaction with clinical symptoms in schizophrenia patients, especially in first-episode drug-naïve (FEDN) patients.

Methods

A total of 119 FEDN schizophrenia patients and 135 healthy controls were recruited for this study. Serum TNF-α, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) were measured. The Positive and Negative Syndrome Scale (PANSS) was applied to evaluate psychotic symptoms. Two-way ANOVA, partial correlation analysis, and multivariate regression analysis were performed.

Results

A sex difference in MDA levels was demonstrated only in healthy controls (F = 7.06, p_Bonferroni = 0.045) and not seen in patients. Furthermore, only male patients had higher MDA levels than male controls (F = 8.19, p_Bonferroni = 0.03). Additionally, sex differences were observed in the association of TNF-α and MDA levels with psychotic symptoms (all p_Bonferroni < 0.05). The interaction of TNF-α and MDA was only associated with general psychopathology symptom in male patients (B = − 0.07, p = 0.02).

Conclusion

Our results demonstrate the sex difference in the relationship between TNF-α, MDA, and their interaction with psychopathological symptoms of patients with schizophrenia.

Paraoxonase 2 deficiency in mice alters motor behavior and causes region-specific transcript changes in the brain

Paraoxonase 2 (PON2) is an intracellular antioxidant enzyme shown to play an important role in mitigating oxidative stress in the brain. Oxidative stress is a common mechanism of toxicity for neurotoxicants and is increasingly implicated in the etiology of multiple neurological diseases. While PON2 deficiency increases oxidative stress in the brain in-vitro, little is known about its effects on behavior in-vivo and what global transcript changes occur from PON2 deficiency. We sought to characterize the effects of PON2 deficiency on behavior in mice, with an emphasis on locomotion, and evaluate transcriptional changes with RNA-Seq. Behavioral endpoints included home-cage behavior (Noldus PhenoTyper), motor coordination (Rotarod) and various gait metrics (Noldus CatWalk). Home-cage behavior analysis showed PON2 deficient mice had increased activity at night compared to wildtype controls and spent more time in the center of the cage, displaying a possible anxiolytic phenotype. PON2 deficient mice had significantly shorter latency to fall when tested on the rotarod, suggesting impaired motor coordination. Minimal gait alterations were observed, with decreased girdle support posture noted as the only significant change in gait with PON2 deficiency. Beyond one home-cage metric, no significant sex-based behavioral differences were found in this study. Finally, A subset of samples were utilized for RNA-Seq analysis, looking at three discrete brain regions: cerebral cortex, striatum, and cerebellum. Highly regional- and sex-specific changes in RNA expression were found when comparing PON2 deficient and wildtype mice, suggesting PON2 may play distinct regional roles in the brain in a sex-specific manner. Taken together, these findings demonstrates that PON2 deficiency significantly alters the brain on both a biochemical and phenotypic level, with a specific impact on motor function. These data have implications for future gene-environment toxicological studies and warrants further investigation of the role of PON2 in the brain.

The associations among organophosphate pesticide exposure, oxidative stress, and genetic polymorphisms of paraoxonases in children with attention deficit/hyperactivity disorder

This study will help to clarify the relationship between organophosphate pesticides (OPs) and attention deficit/hyperactivity disorder (ADHD) related to oxidative stress and paraoxonases (PON) polymorphisms to further characterize the gene-environment interaction. This case-control study enrolled 85 children with ADHD and 96 control subjects. Urinary OP levels were analyzed by using gas chromatography-mass spectrometry (GC-MS). Oxidative stress biomarkers, such as 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO2-Gua), 8-iso-prostaglandin F2α (8-iso-PGF2α), and 4-hydroxy-2-nonenoic acid-mercapturic acid (HNE-MA), were analyzed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (S) were calculated to evaluate the additive interactions between OP exposure and PON genetic polymorphism on ADHD. A causal mediation analysis was conducted to clarify the mediation effects of oxidative stress due to OP exposure on ADHD. Children with ADHD had significantly higher DMP (238.95 nmol/g cre. vs. 164.83 nmol/g cre., p value = 0.01) and HNE-MA (30.75 μg/g cre. vs. 18.41 μg/g cre., p value<0.01) concentrations than control children. Children who carried the PON1 GG genotype (rs705379) had low urinary DMP levels, and the level increased with increasing numbers of allele variants. The risk for developing ADHD reached 2.06-fold (OR = 2.06, 95% CI:1.23-3.44) and 1.43-fold (OR = 1.45, 95% CI:1.04-2.03) when the DMP and HNE-MA levels increased by 1 natural log of the concentration, respectively. The estimated AP value was 0.66 (95% CI: 0.17-1.15), indicating that 66% of ADHD cases in DMP-exposed children with the PON1 CT/TT (rs705381) genotype were due to gene-environment interactions. No significant mediation of HNE-MA was observed between DMP exposure and the risk of ADHD. The estimated proportion mediated was only 7.0% (95% CI: -0.08-0.46). This research suggests the role of OP exposure in the occurrence of ADHD after adjusting for covariates.

Mechanistic insights and perspectives involved in neuroprotective action of quercetin

Neurodegenerative diseases (NDDs) are the primary cause of disabilities in the elderly people. Growing evidence indicates that oxidative stress, mitochondrial dysfunction, neuroinflammation and apoptosis are associated with aging and the basis of most neurodegenerative disorders. Quercetin is a flavonoid with significant pharmacological effects and promising therapeutic potential. It is widely distributed among plants and typically found in daily diets mainly in fruits and vegetables. It shows a number of biological properties connected to its antioxidant activity. Neuroprotection by quercetin has been reported in many in vitro as well as in in vivo studies. However, the exact mechanism of action is still mystery and similarly there are a number of hypothesis exploring the mechanism of neuroprotection. Quercetin enhances neuronal longevity and neurogenesis by modulating and inhibiting wide number of pathways. This review assesses the food sources of quercetin, its pharmacokinetic profile, structure activity relationship and its pathophysiological role in various NDDs and it also provides a synopsis of the literature exploring the relationship between quercetin and various downstream signalling pathways modulated by quercetin for neuroprotection for eg. nuclear factor erythroid 2-related factor 2 (Nrf2), Paraoxonase-2 (PON2), c-Jun N-terminal kinase (JNK), Tumour Necrosis Factor alpha (TNF-α), Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α), Sirtuins, Mitogen-activated protein kinases (MAPKs) signalling cascades, CREB (Cyclic AMP response element binding protein) and Phosphoinositide 3- kinase(PI3K/Akt). Therefore, the aim of the present review was to elaborate on the cellular and molecular mechanisms of the quercetin involved in the protection against NDDs.

Impact of intrauterine fetal resuscitation with oxygen on oxidative stress in the developing rat brain

Use of maternal oxygen for intrauterine resuscitation is contentious because of the lack of evidence for its efficacy and the possibility of fetal harm through oxidative stress. Because the developing brain is rich in lipids and low in antioxidants, it remains vulnerable to oxidative stress. Here, we tested this hypothesis in a term pregnant rat model with oxytocin-induced fetal distress followed by treatment with either room air or 100% oxygen for 6 h. Fetal brains from both sexes were subjected to assays for biomarkers of oxidative stress (4-hydroxynonenal, protein carbonyl, or 8-hydroxy-2'-deoxyguanosine), expression of genes mediating oxidative stress, and mitochondrial oxidative phosphorylation. Contrary to our hypothesis, maternal hyperoxia was not associated with increased biomarkers of oxidative stress in the fetal brain. However, there was significant upregulation of the expression of select genes mediating oxidative stress, of which some were male-specific. These observations, however, were not accompanied by changes in the expression of proteins from the mitochondrial electron transport chain. In summary, maternal hyperoxia in the setting of acute uteroplacental ischemia-hypoxia does not appear to cause oxidative damage to the developing brain.

Sex-based disparity in paraoxonase-2 expression in the brains of African green monkeys

The development of several neurodegenerative disorders, such as Parkinson's disease, has been linked with decreased mitochondrial performance, leading to oxidative stress as a result of increased production of reactive oxygen species (ROS). Previous studies have established that the mitochondrial enzyme, paraoxonase-2 (PON2), possesses potent antioxidant and anti-inflammatory properties, with its expression linked with lower ROS levels. The aim of this study was to explore the sex-based variations in the protein level of PON2 in different brain regions (striatum, hippocampus, occipital cortex, and dorsolateral prefrontal cortex) of African green monkeys. Our results revealed that the PON2 expression in females was significantly higher than in males, in each of the examined brain regions. As Parkinson's disease is more prevalent in males compared with females and is characterized by oxidative stress in the nigrostriatal system, these findings add to the growing evidence for PON2 as a target for development of therapeutics to combat this disorder.

Environmental enrichment applied with sensory components prevents age-related decline in synaptic dynamics: Evidence from the zebrafish model organism

Progression of cognitive decline with or without neurodegeneration varies among elderly subjects. The main aim of the current study was to illuminate the molecular mechanisms that promote and retain successful aging in the context of factors such as environment and gender, both of which alter the resilience of the aging brain. Environmental enrichment (EE) is one intervention that may lead to the maintenance of cognitive processing at older ages in both humans and animal subjects. EE is easily applied to different model organisms, including zebrafish, which show similar age-related molecular and behavioral changes as humans. Global changes in cellular and synaptic markers with respect to age, gender and 4-weeks of EE applied with sensory stimulation were investigated using the zebrafish model organism. Results indicated that EE increases brain weight in an age-dependent manner without affecting general body parameters like body mass index (BMI). Age-related declines in the presynaptic protein synaptophysin, AMPA-type glutamate receptor subunits and a post-mitotic neuronal marker were observed and short-term EE prevents these changes in aged animals, as well as elevates levels of the inhibitory scaffolding protein, gephyrin. Gender-driven alterations were observed in the levels of the glutamate receptor subunits. Oxidative stress markers were significantly increased in the old animals, while exposure to EE did not alter this pattern. These data suggest that EE with sensory stimulation exerts its effects mainly on age-related changes in synaptic dynamics, which likely increase brain resilience through specific cellular mechanisms.

PPARγ/PGC1α signaling as a potential therapeutic target for mitochondrial biogenesis in neurodegenerative disorders

Neurodegenerative diseases represent some of the most devastating neurological disorders, characterized by progressive loss of the structure and function of neurons. Current therapy for neurodegenerative disorders is limited to symptomatic treatment rather than disease modifying interventions, emphasizing the desperate need for improved approaches. Abundant evidence indicates that impaired mitochondrial function plays a crucial role in pathogenesis of many neurodegenerative diseases and so biochemical factors in mitochondria are considered promising targets for pharmacological-based therapies. Peroxisome proliferator-activated receptors-γ (PPARγ) are ligand-inducible transcription factors involved in regulating various genes including peroxisome proliferator-activated receptor gamma co-activator-1 alpha (PGC1α). This review summarizes the evidence supporting the ability of PPARγ-PGC1α to coordinately up-regulate the expression of genes required for mitochondrial biogenesis in neurons and provide directions for future work to explore the potential benefit of targeting mitochondrial biogenesis in neurodegenerative disorders. We have highlighted key roles of NRF2, uncoupling protein-2 (UCP2), and paraoxonase-2 (PON2) signaling in mediating PGC1α-induced mitochondrial biogenesis. In addition, the status of PPARγ modulators being used in clinical trials for Parkinson's disease (PD), Alzheimer's disease (AD) and Huntington's disease (HD) has been compiled. The overall purpose of this review is to update and critique our understanding of the role of PPARγ-PGC1α-NRF2 in the induction of mitochondrial biogenesis together with suggestions for strategies to target PPARγ-PGC1α-NRF2 signaling in order to combat mitochondrial dysfunction in neurodegenerative disorders.

Paraoxonase 2 protects against oxygen-glucose deprivation/reoxygenation-induced neuronal injury by enhancing Nrf2 activation via GSK-3β modulation

Paraoxonase 2 (PON2) is a powerful antioxidant that mediates cell survival under oxidative stress; however, its protection neurons against cerebral ischemia-reperfusion injury-induced oxidative stress remains unclear. This study aimed to determine the precise regulating role of PON2 in neuronal survival under oxidative stress. An in vitro model of cerebral ischemia-reperfusion injury was used to assess the effect of PON2 on oxidative stress induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Results showed that PON2 expression in neurons was decreased due to OGD/R exposure. A series of functional experiments revealed that upregulated PON2 improved OGD/R-impaired viability and attenuated OGD/R-induced increases in apoptosis and reactive oxygen species in neurons. Decreased PON2 expression enhanced neuronal sensitivity to OGD/R-induced injury. Overexpressed PON2 markedly enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the nucleus and increased the levels of Nrf2-mediated transcriptional activity. Furthermore, PON2 enhanced the Nrf2 activation by modulating glycogen synthase kinase-3β (GSK-3β). Inhibition of GSK-3β substantially abrogated the PON2 knockdown-mediated suppression of Nrf2 activity. Notably, Nrf2 inhibition partially reversed the neuroprotective effects of PON2 overexpression in OGD/R-exposed neurons. These findings indicate that PON2 alleviates OGD/R-induced apoptosis and oxidative stress in neurons by potentiating Nrf2 activation via GSK-3β modulation. This study highlights the potential neuroprotective function of PON2 against cerebral ischemia-reperfusion injury.

Hippocampal inflammation and oxidative stress following exposure to diesel exhaust nanoparticles in male and female mice

Air pollution exposure is among the most prevalent reasons for environmentally-induced oxidative stress and inflammation, both of which are involved in the development and progression of central nervous system (CNS) diseases. Ultrafine particles (UFPs) plays an important role in global air pollution and the diesel exhaust particles (DEPs) are the most important component in this regard. There are more than 40 toxic air pollutants in diesel exhaust (DE), which is one of the main constituents of an environmental pollutant and including particulate matter (PM) especially UFPs. Thus, in this study, adult female and male NMRI mice were exposed to DEPs (350-400 μg/m³) for 14 weeks (6 h per day and 5 days per week). After 14 weeks of exposure, expression of pro-inflammatory cytokines (IL-1α, IL-1β, IL-6, TNF-α), nNOS, HO1, NR2A, and NR2B and malondialdehyde (MDA) level were analyzed in various brain regions such as the hippocampus (HI) and olfactory bulb (OB). Exposure to DEPs caused neuroinflammation and oxidative stress in female and male mice. That these effects observed in females were less pronounced than in male mice. The male mice emerged to be more susceptible significantly than the female mice to induced neuroinflammation following DEPs exposure. Also, our findings indicate that long term exposure to DEPs results in altered expression of hippocampal NMDA receptor subunits, and suggests that gender can play important role in the modulating susceptibility to neurotoxicity induced by DEPs exposure.

The Structure and Function of Paraoxonase-1 and Its Comparison to Paraoxonase-2 and -3

Serum paraoxonase-1 (PON1) is the most studied member of the group of paraoxonases (PONs). This enzyme possesses three enzymatic activities: lactonase, arylesterase, and paraoxonase activity. PON1 and its isoforms play an important role in drug metabolism as well as in the prevention of cardiovascular and neurodegenerative diseases. Although all three members of the PON family have the same origin and very similar amino acid sequences, they have different functions and are found in different locations. PONs exhibit substrate promiscuity, and their true physiological substrates are still not known. However, possible substrates include homocysteine thiolactone, an analogue of natural quorum-sensing molecules, and the recently discovered derivatives of arachidonic acid—bioactive δ-lactones. Directed evolution, site-directed mutagenesis, and kinetic studies provide comprehensive insights into the active site and catalytic mechanism of PON1. However, there is still a whole world of mystery waiting to be discovered, which would elucidate the substrate promiscuity of a group of enzymes that are so similar in their evolution and sequence yet so distinct in their function.

Protection induced by estradiol benzoate in the MPP+ rat model of Parkinson's disease is associated with the regulation of the inflammatory cytokine profile in the nigro striatum

Previously, we have demonstrated that β-estradiol-3-benzoate (EB) has a protective effect on the neurodegenerative experimental model of Parkinson's disease. The protective effect is through the induction of the expression of paraoxonase-2 (PON2) in the striatum. PON2 has proven to have antioxidant and anti-inflammatory activity, this protein has a beneficial effect in MPP⁺ model in rats decreasing the lipid peroxidation and the oxidative stress. Furthermore, the molecular effect and the pathway by which EB induces protection were not further pursued. This study shows the regulation by EB of the anti-inflammatory effect through the modulation of cytokines, antioxidant enzymes and PON2 in the rat striatum. Rats were gonadectomized and 30 days after were randomly assigned into four experimental groups; only vehicles (Control group); EB treatment (EB group); MPP⁺ injury (M group); EB plus MPP⁺ injured (EB/M group). EB treatment consisted of 100 μg of the drug administered every 48 h for 11 days. Results showed that EB (group EB/M) treatment decrease significantly (40%) the number of ipsilateral turns respect to the M group and prevents significantly the dopamine (DA) decreased induced by MPP⁺ (~75%). This results are correlate with a significant decrease in the level of lipid peroxidation (60%) of the EB/M group respect to the M group. The EB treatment showed protection against neurotoxicity induced with MPP⁺, this could be due to EB capacity to prevent the increase in the expression level of proinflammatory cytokines TNF-α, IL-1 and IL-6 induced by MPP⁺. While, TGF-β1 and TGF-β3 expression was reduced in the rats treated only with MPP⁺, in the rats of EB/M group the expression of both cytokines was increased. EB protective effect against MPP⁺ neurotoxicity is related to antioxidant effect of PON2, pro-inflammatory cytokines and GSHR but not to SOD2, catalase, GPX1 or GPX4.

PON1 Hypermethylation and PON3 Hypomethylation are Associated with Risk of Cerebral Infarction

OBJECTIVE

Paraoxonase (PON) family genes are closely related to the etiology and prognosis of cerebral infarction. This study explored the association of the promoter methylation of PON family genes (PON1, PON2 and PON3) with the risk of cerebral infarction.

MATERIALS AND METHODS

In this study, 152 patients with confirmed cerebral infarction were selected as the case group, and 152 healthy controls were selected as the control group. The quantitative methylation-specific PCR (qMSP) was used to determine the promoter methylation levels of PON1, PON2 and PON3 genes. The methylation level was expressed as a methylation reference percentage (PMR).

RESULTS

Our results indicated that PON1 methylation was significantly higher in the case group than in the control group (P = 0.0001). On the contrary, PON3 methylation was significantly lower in the case group than in the control group (P = 0.002). In addition, we found that PON2 gene had a very low level of methylation in both case and control groups (PMR = 0). Subgroup analysis showed that PON1 and PON3 methylation were associated with cerebral infarction only in males (PON1, P = 0.0002; PON3, P = 0.007). Interestingly, the methylation levels of PON1 and PON3 were correlated with each other (case: r = 0.418, P = 0.0001; control: r = 0.3, P = 0.0002). Further multiple regression analysis suggested that elevated methylation levels of PON3 were a protective factor for cerebral infarction [OR (95%CI) = 0.979 (0.96, 0.999), β = -0.021, P = 0.035)], highdensity lipoprotein (HDL) and uric acid (UA) also were protective factors for cerebral infarction [HDL, OR (95% CI) = 0.01 (0.003, 0.033), P < 0.0001); UA, OR (95% CI) = 0.995 (0.991, 0.998), P = 0.003)]. The ROC curve analysis found that the combination of PON3, HDL, and UA had a good predictive power for cerebral infarction (AUC=0.878, 95% CI=0.839-0.918, sensitivity 73.7%, specificity 89.7%, P < 0.0001).

CONCLUSION

PON1 and PON3 promoter methylation levels in peripheral blood were closely related. PON1 and PON3 methylation were associated with the risk of cerebral infarction in men. PON3 promoter methylation combined with HDL and UA could be used as potential biomarkers for the diagnosis of cerebral infarction.

Effects of air pollution on the nervous system and its possible role in neurodevelopmental and neurodegenerative disorders

Recent extensive evidence indicates that air pollution, in addition to causing respiratory and cardiovascular diseases, may also negatively affect the brain and contribute to central nervous system diseases. Air pollution is comprised of ambient particulate matter (PM) of different sizes, gases, organic compounds, and metals. An important contributor to PM is represented by traffic-related air pollution, mostly ascribed to diesel exhaust (DE). Epidemiological and animal studies have shown that exposure to air pollution may be associated with multiple adverse effects on the central nervous system. In addition to a variety of behavioral abnormalities, the most prominent effects caused by air pollution are oxidative stress and neuro-inflammation, which are seen in both humans and animals, and are supported by in vitro studies. Among factors which can affect neurotoxic outcomes, age is considered most relevant. Human and animal studies suggest that air pollution may cause developmental neurotoxicity, and may contribute to the etiology of neurodevelopmental disorders, including autism spectrum disorder. In addition, air pollution exposure has been associated with increased expression of markers of neurodegenerative disease pathologies, such as alpha-synuclein or beta-amyloid, and may thus contribute to the etiopathogenesis of neurodegenerative diseases, particularly Alzheimer's disease and Parkinson's disease.

In utero exposure to transient ischemia-hypoxemia promotes long-term neurodevelopmental abnormalities in male rat offspring

The impact of transient ischemic-hypoxemic insults on the developing fetal brain is poorly understood despite evidence suggesting an association with neurodevelopmental disorders such as schizophrenia and autism. To address this, we designed an aberrant uterine hypercontractility paradigm with oxytocin to better assess the consequences of acute, but transient, placental ischemia-hypoxemia in term pregnant rats. Using MRI, we confirmed that oxytocin-induced aberrant uterine hypercontractility substantially compromised uteroplacental perfusion. This was supported by the observation of oxidative stress and increased lactate concentration in the fetal brain. Genes related to oxidative stress pathways were significantly upregulated in male, but not female, offspring 1 hour after oxytocin-induced placental ischemia-hypoxemia. Persistent upregulation of select mitochondrial electron transport chain complex proteins in the anterior cingulate cortex of adolescent male offspring suggested that this sex-specific effect was enduring. Functionally, offspring exposed to oxytocin-induced uterine hypercontractility showed male-specific abnormalities in social behavior with associated region-specific changes in gene expression and functional cortical connectivity. Our findings, therefore, indicate that even transient but severe placental ischemia-hypoxemia could be detrimental to the developing brain and point to a possible mitochondrial link between intrauterine asphyxia and neurodevelopmental disorders.

Antioxidant status of uric acid, bilirubin, albumin and creatinine during the acute phase after traumatic brain injury: sex-specific features

BACKGROUND

It is known that the alteration of antioxidants can been seen in early phase after traumatic brain injury (TBI) in order to block oxidative damage, but little is known about the influence of sex on antioxidant system in patients with TBI. This study investigates whether there are sex differences in these endogenous antioxidant agents during the acute phase after TBI and their association with the disease.

METHODS

Serum levels of uric acid (UA), bilirubin, albumin and creatinine were measured in 421 individuals included 157 female TBI patients, 156 male TBI patients and 108 age- and sex-matched controls.

RESULTS

The statistically significant changes were found in UA, bilirubin, albumin and creatinine for both sexes with TBI, but the trend of changes in bilirubin and creatinine was opposite for gender groups. Serum levels of UA, bilirubin, albumin and creatinine were associated with the severity of TBI patients for both sexes. Male patient subgroups with elevated UA, albumin and creatinine had higher frequency of regaining consciousness in a month. Moreover, addition of UA and creatinine to the established clinical model had significantly improved the predictive performance over using clinical model alone in male patients with TBI. However, no similar findings were observed on female TBI patients.

CONCLUSION

Our results suggest sex-based differences in the serum endogenous antioxidant response to TBI. Use of serum UA and creatinine could help in the outcome prediction of male patients with TBI in combination with other prognostic factors.

Association Between Outdoor Air Pollution and Risk of Malignant and Benign Brain Tumors: The Multiethnic Cohort Study

Background

There are increasing concerns about the potential impact of air pollution on chronic brain inflammation and microglia cell activation, but evidence of its carcinogenic effects is limited.

Methods

We used kriging interpolation and land use regression models to estimate long-term air pollutant exposures of oxides of nitrogen (NO_x, NO₂), kriging interpolation for ozone (O₃), carbon monoxide, and particulate matter (PM_2.5, PM₁₀), and nearest monitoring station measurements for benzene for 103 308 men and women from the Multiethnic Cohort, residing largely in Los Angeles County from recruitment (1993–1996) through 2013. We used Cox proportional hazards models to examine the associations between time-varying pollutants and risk of malignant brain cancer (94 men, 116 women) and meningioma (130 men, 425 women) with adjustment for sex, race and ethnicity, neighborhood socioeconomic status, smoking, occupation, and other covariates. Stratified analyses were conducted by sex and race and ethnicity.

Results

Brain cancer risk in men increased in association with exposure to benzene (hazard ratio [HR] = 3.52, 95% confidence interval [CI] = 1.55 to 7.55) and PM₁₀ (HR = 1.80, 95% CI = 1.00 to 3.23). Stronger associations with PM₁₀ (HR = 3.02, 95% CI = 1.26 to 7.23), O₃ (HR = 2.93, 95% CI = 1.09 to 7.88), and benzene (HR = 4.06, 95% CI = 1.17 to 18.2) were observed among Latino men. Air pollution was unrelated to risk of meningioma except that O₃ exposure was associated with risk in men (HR = 1.77, 95% CI = 1.02 to 3.06). Brain cancer risk in women was unrelated to air pollution exposures.

Conclusions

Confirmation of these sex differences in air pollution–brain cancer associations and the stronger findings in Latino men in additional diverse populations is warranted.

Novel QUEST MRI In Vivo Measurement of Noise-induced Oxidative Stress in the Cochlea

Effective personalized therapeutic treatment for hearing loss is currently not available. Cochlear oxidative stress is commonly identified in the pathogenesis of hearing loss based upon findings from excised tissue, thus suggesting a promising druggable etiology. However, the timing and site(s) to target for anti-oxidant treatment in vivo are not clear. Here, we address this long-standing problem with QUEnch-assiSTed Magnetic Resonance Imaging (QUEST MRI), which non-invasively measures excessive production of free radicals without an exogenous contrast agent. QUEST MRI is hypothesized to be sensitive to noise-evoked cochlear oxidative stress in vivo. Rats exposed to a loud noise event that resulted in hair cell loss and reduced hearing capability had a supra-normal MRI R1 value in their cochleae that could be corrected with anti-oxidants, thus non-invasively indicating cochlear oxidative stress. A gold-standard oxidative damage biomarker [heme oxidase 1 (HO-1)] supported the QUEST MRI result. The results from this study highlight QUEST MRI as a potentially transformative measurement of cochlear oxidative stress in vivo that can be used as a biomarker for improving individual evaluation of anti-oxidant treatment efficacy in currently incurable oxidative stress-based forms of hearing loss.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

Oxidative Stress: A Major Player in Cerebrovascular Alterations Associated to Neurodegenerative Events

The brain is one of the most exquisite organs in the body with high metabolic demands, and requires a tight regulation of the surrounding environment. This tight control is exerted by the neurovascular unit (NVU) comprising different cell types, where endothelial cells play the commander-in-chief role. Thus, it is assumable that even slight perturbations in NVU might affect, in some cases irreversibly, brain homeostasis and health. In this line, recent findings support the two-hit vascular hypothesis for neurodegenerative conditions, where vascular dysfunction underlies the development of neurodegenerative diseases, such as Alzheimer’s disease (AD). Knowing that endothelial cells are rich in mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, two major reactive oxygen species (ROS) sources, this review aims to gather information on how oxidative stress is in the front line of vascular alterations observed in brain aging and neurodegenerative conditions, particularly AD. Also, a brief discussion about the therapeutic strategies aimed to protect against cerebrovascular diseases is included.

Early Prediction of Hypoxic-Ischemic Brain Injury by a New Panel of Biomarkers in a Population of Term Newborns

This research paper is aimed at evaluating the predictive role of a default panel of oxidative stress (OS) biomarkers for the early identification of infants at high risk of HIE and their validation through the correlation with MRI findings. A multicenter prospective observational study was performed between March 2012 and April 2015 in two European tertiary NICUs. Eighty-four term infants at risk for HIE (pH < 7, BE < −13 mmol/L, and 5′ Apgar < 5) were enrolled. Three were excluded for chromosomal abnormalities and one due to lack of blood samples. The final population was divided according to the severity of perinatal hypoxia into 2 groups: mild/moderate HIE and severe HIE. Advanced oxidation protein products (AOPP), non-protein-bound iron (NPBI), and F2-isoprostanes (F2-IsoPs) were measured in blood samples at P1 (4–6 hours), P2 (24–72 hours), and P3 (5 days), in both groups. MRIs were scored for the severity of brain injury, using a modified Barkovich score. The mean GA was 39.8 weeks (SD 1.4) and the mean birth weight 3538 grams (SD 660); 37 were females and 43 males. Significantly lower 5′ Apgar score, pH, and BE and higher Thompson score were found in group II compared to group I at birth. Group II showed significantly higher AOPP and NPBI levels than group I (mean (SD) AOPP: 15.7 (15.5) versus 34.1 (39.2), p = 0.033; NPBI 1.1 (2.5) versus 3.9 (4.4), p = 0.013) soon after birth (P1). No differences were observed in OS biomarker levels between the two groups at P2 and P3. A regression model, including adjustment for hypothermia treatment, gender, and time after birth, showed that AOPP levels and male gender were both risk factors for higher brain damage scores (AOPP: OR 3.6, 95% CI (1.1–12.2) and gender: OR 5.6, 95% CI (1.2–25.7), resp.). Newborns with severe asphyxia showed higher OS than those with mild asphyxia at birth. AOPP are significantly associated with the severity of brain injury assessed by MRI, especially in males.

Sex Differences in Neurotoxicogenetics

A major development in biomedical research is the recognition that the sex of an individual plays a key role in susceptibility, treatment, and outcomes of most diseases. In this contribution, we present evidence that sex is also important in the toxicity of many environmental toxicants and contributes to the effect of genetics. Thus, individual differences in response to toxicants includes genetic makeup, the environment and sex; in fact, sex differences may be considered a part of genetic constitution. In this review, we present evidence for sex contribution to susceptibility for a number of toxicants.

Paraoxonase 2 prevents the development of heart failure

BACKGROUND

Mitochondrial oxidation is a major source of reactive oxygen species (ROS) and mitochondrial dysfunction plays a central role in development of heart failure (HF). Paraoxonase 2 deficient (PON2-def) mitochondria are impaired in function. In this study, we tested whether PON2-def aggravates HF progression.

METHODS AND RESULTS

Using qPCR, immunoblotting and lactonase activity assay, we demonstrate that PON2 activity was significantly decreased in failing hearts despite increased PON2 expression. To determine the cardiac-specific function of PON2, we performed heart transplantations in which PON2-def and wild type (WT) donor hearts were implanted into WT recipient mice. Beating scores of the donor hearts, assessed at 4 weeks post-transplantation, were significantly decreased in PON2-def hearts when compared to WT donor hearts. By using a transverse aortic constriction (TAC) model, we found PON2 deficiency significantly exacerbated left ventricular remodeling and cardiac fibrosis post-TAC. We further demonstrated PON2 deficiency significantly enhanced ROS generation in heart tissues post-TAC. ROS generation was measured through dihydroethidium (DHE) using high-pressure liquid chromatography (HPLC) with a fluorescent detector. By using neonatal cardiomyocytes treated with CoCl₂ to mimic hypoxia, we found PON2 deficiency dramatically increased ROS generation in the cardiomyocytes upon CoCl₂ treatment. In response to a short CoCl₂ exposure, cell viability and succinate dehydrogenase (SDH) activity assessed by MTT assay were significantly diminished in PON2-def cardiomyocytes compared to those in WT cardiomyocytes. PON2-def cardiomyocytes also had lower baseline SDH activity. By using adult mouse cardiomyocytes and mitochondrial ToxGlo assay, we found impaired cellular ATP generation in PON2-def cells compared to that in WT cells, suggesting that PON2 is necessary for proper mitochondrial function.

CONCLUSION

Our study suggests a cardioprotective role for PON2 in both experimental and human heart failure, which may be associated with the ability of PON2 to improve mitochondrial function and diminish ROS generation.

Traffic-Related Air Pollution and Autism Spectrum Disorder: A Population-Based Nested Case-Control Study in Israel

Accumulating evidence suggests that perinatal air pollutant exposures are associated with increased risk of autism spectrum disorder (ASD), but evidence for traffic pollutants outside the United States is inconclusive. We assessed the association between nitrogen dioxide, a traffic pollution tracer, and risk of ASD. We conducted a nested case-control study among the entire population of children born during 2005-2009 in the central coastal area of Israel. Cases were identified through the National Insurance Institute of Israel (n = 2,098). Controls were a 20% random sample of the remaining children (n = 54,191). Exposure was based on an optimized dispersion model. We estimated adjusted odds ratios and 95% confidence intervals using logistic regression and a distributed-lag model. In models mutually adjusted for the 2 periods, the odds ratio per 5.85-parts per billion (ppb) increment of nitrogen dioxide exposure during pregnancy (median, 16.8 ppb; range, 7.5-31.2 ppb) was 0.77 (95% confidence interval: 0.59, 1.00), and the odds ratio for exposure during the 9 months after birth was 1.40 (95% confidence interval: 1.09, 1.80). A distributed-lag model revealed reduced risk around week 13 of pregnancy and elevated risk around week 26 after birth. These findings suggest that postnatal exposure to nitrogen dioxide in Israel is associated with increased odds of ASD, and prenatal exposure with lower odds. The latter may relate to selection effects.

Exploring the role of paraoxonase-2 in bladder cancer: analyses performed on tissue samples, urines and cell cultures

The enzyme paraoxonase-2 (PON2) is ubiquitously expressed and exerts its antiapoptotic and antioxidative functions in several intracellular compartments.The aim of this study is to investigate the role of PON2 in bladder cancer (BC). The expression levels of PON2 in paired tumor and normal bladder tissue samples and in urinary exfoliated cells from patients affected with BC and healthy donors were evaluated. Moreover, the effect of PON2 overexpression on tumor cell proliferation and susceptibility to oxidative stress was investigated in human bladder cancer cell line T24.Our results showed that PON2 expression levels were significantly higher in BC compared with non-tumor tissue. In urinary exfoliated cells from BC patients, PON2 mRNA levels showed an inverse correlation with tumor stage (pT). Moreover, PON2 overexpression in T24 cells led to a significant increase in tumor cell proliferation and resistance to oxidative stress.The results obtained showed that PON2 could represent a molecular biomarker for bladder cancer and suggest a potential role of the enzyme as a prognostic factor for this neoplasm.

Acute exposure to diesel exhaust impairs adult neurogenesis in mice: prominence in males and protective effect of pioglitazone

Adult neurogenesis is the process by which neural stem cells give rise to new functional neurons in specific regions of the adult brain, a process that occurs throughout life. Significantly, neurodegenerative and psychiatric disorders present suppressed neurogenesis, activated microglia, and neuroinflammation. Traffic-related air pollution has been shown to adversely affect the central nervous system. As the cardinal effects of air pollution exposure are microglial activation, and ensuing oxidative stress and neuroinflammation, we investigated whether acute exposures to diesel exhaust (DE) would inhibit adult neurogenesis in mice. Mice were exposed for 6 h to DE at a PM_2.5 concentration of 250-300 μg/m³, followed by assessment of adult neurogenesis in the hippocampal subgranular zone (SGZ), the subventricular zone (SVZ), and olfactory bulb (OB). DE impaired cellular proliferation in the SGZ and SVZ in males, but not females. DE reduced adult neurogenesis, with male mice showing fewer new neurons in the SGZ, SVZ, and OB, and females showing fewer new neurons only in the OB. To assess whether blocking microglial activation protected against DE-induced suppression of adult hippocampal neurogenesis, male mice were pre-treated with pioglitazone (PGZ) prior to DE exposure. The effects of DE exposure on microglia, as well as neuroinflammation and oxidative stress, were reduced by PGZ. PGZ also antagonized DE-induced suppression of neurogenesis in the SGZ. These results suggest that DE exposure impairs adult neurogenesis in a sex-dependent manner, by a mechanism likely to involve microglia activation and neuroinflammation.

Sex differences in brain mitochondrial metabolism: influence of endogenous steroids and stroke

Steroids are neuroprotective and a growing body of evidence indicates that mitochondria are a potential target of their effects. The mitochondria are the site of cellular energy synthesis, regulate oxidative stress and play a key role in cell death after brain injury and neurodegenerative diseases. After providing a summary of the literature on the general functions of mitochondria and the effects of sex steroid administrations on mitochondrial metabolism, we summarise and discuss our recent findings concerning sex differences in brain mitochondrial function under physiological and pathological conditions. To analyse the influence of endogenous sex steroids, the oxidative phosphorylation system, mitochondrial oxidative stress and brain steroid levels were compared between male and female mice, either intact or gonadectomised. The results obtained show that females have higher a mitochondrial respiration and lower oxidative stress compared to males and also that these differences were suppressed by ovariectomy but not orchidectomy. We have also shown that the decrease in brain mitochondrial respiration induced by ischaemia/reperfusion is different according to sex. In both sexes, treatment with progesterone reduced the ischaemia/reperfusion-induced mitochondrial alterations. Our findings indicate sex differences in brain mitochondrial function under physiological conditions, as well as after stroke, and identify mitochondria as a target of the neuroprotective properties of progesterone. Thus, it is necessary to investigate sex specificity in brain physiopathological mechanisms, especially when mitochondria impairment is involved.

Role of Sex Hormones on Brain Mitochondrial Function, with Special Reference to Aging and Neurodegenerative Diseases

The mitochondria have a fundamental role in both cellular energy supply and oxidative stress regulation and are target of the effects of sex steroids, particularly the neuroprotective ones. Aging is associated with a decline in the levels of different steroid hormones, and this decrease may underline some neural dysfunctions. Besides, modifications in mitochondrial functions associated with aging processes are also well documented. In this review, we will discuss studies that describe the modifications of brain mitochondrial function and of steroid levels associated with physiological aging and with neurodegenerative diseases. A special emphasis will be placed on describing and discussing our recent findings concerning the concomitant study of mitochondrial function (oxidative phosphorylation, oxidative stress) and brain steroid levels in both young (3-month-old) and aged (20-month-old) male and female mice.