miR-205/IRAK2 signaling pathway is associated with urban airborne PM2.5-induced myocardial toxicity

The effects of fine particulate matter on the blood-testis barrier and its potential mechanisms

With the rapid expansion of industrial scale, an increasing number of fine particulate matter (PM2.5) has bringing health concerns. Although exposure to PM2.5 has been clearly associated with male reproductive toxicity, the exact mechanisms are still unclear. Recent studies demonstrated that exposure to PM2.5 can disturb spermatogenesis through destroying the blood-testis barrier (BTB), consisting of different junction types, containing tight junctions (TJs), gap junctions (GJs), ectoplasmic specialization (ES) and desmosomes. The BTB is one of the tightest blood-tissue barriers among mammals, which isolating germ cells from hazardous substances and immune cell infiltration during spermatogenesis. Therefore, once the BTB is destroyed, hazardous substances and immune cells will enter seminiferous tubule and cause adversely reproductive effects. In addition, PM2.5 also has shown to cause cells and tissues injury via inducing autophagy, inflammation, sex hormones disorder, and oxidative stress. However, the exact mechanisms of the disruption of the BTB, induced by PM2.5, are still unclear. It is suggested that more research is required to identify the potential mechanisms. In this review, we aim to understand the adverse effects on the BTB after exposure to PM2.5 and explore its potential mechanisms, which provides novel insight into accounting for PM2.5-induced BTB injury.

MicroRNA205: A Key Regulator of Cardiomyocyte Transition from Proliferative to Hypertrophic Growth in the Neonatal Heart

The mammalian myocardium grows rapidly during early development due to cardiomyocyte proliferation, which later transitions to cell hypertrophy to sustain the heart's postnatal growth. Although this cell transition in the postnatal heart is consistently preserved in mammalian biology, little is known about the regulatory mechanisms that link proliferation suppression with hypertrophy induction. We reasoned that the production of a micro-RNA(s) could serve as a key bridge to permit changes in gene expression that control the changed cell fate of postnatal cardiomyocytes. We used sequential expression analysis to identify miR205 as a micro-RNA that was uniquely expressed at the cessation of cardiomyocyte growth. Cardiomyocyte-specific miR205 deletion animals showed a 35% increase in heart mass by 3 months of age, with commensurate changes in cell cycle and Hippo pathway activity, confirming miR205's potential role in controlling cardiomyocyte proliferation. In contrast, overexpression of miR205 in newborn hearts had little effect on heart size or function, indicating a complex, probably redundant regulatory system. These findings highlight miR205's role in controlling the shift from cardiomyocyte proliferation to hypertrophic development in the postnatal period.

Long-Term Exposure to Ambient PM2.5 and Hospitalizations for Myocardial Infarction Among US Residents: A Difference-in-Differences Analysis

Background Air pollution has been recognized as an untraditional risk factor for myocardial infarction (MI). However, the MI risk attributable to long-term exposure to fine particulate matter ≤2.5 μm in aerodynamic diameter (PM2.5) is unclear, especially in younger populations, and few studies have represented the general population or had power to examine comorbidities. Methods and Results We applied the difference-in-differences approach to estimate the relationship between annual PM2.5 exposure and hospitalizations for MI among US residents and further identified potential susceptible subpopulations. All hospital admissions for MI in 10 US states over the period 2002 to 2016 were obtained from the Healthcare Cost and Utilization Project State Inpatient Database. In total, 1 914 684 MI hospital admissions from 8106 zip codes were included in this study. We observed a 1.35% (95% CI, 1.11-1.59) increase in MI hospitalization rate for 1-μg/m3 increase in annual PM2.5 exposure. The estimate was robust to adjustment for surface pressure, relative humidity, and copollutants. In the population exposed to ≤12 μg/m3, there was a larger increment of 2.17% (95% CI, 1.79-2.56) in hospitalization rate associated with 1-μg/m3 increase in PM2.5. Young people (0-34 years of age) and elderly people (≥75 years of age) were the 2 most susceptible age groups. Residents living in more densely populated or poorer areas and individuals with comorbidities were observed to be at a greater risk. Conclusions This study indicates long-term residential exposure to PM2.5 could increase risk of MI among the general US population, people with comorbidities, and poorer individuals. The association persists below current standards.

Impacts and potential mechanisms of fine particulate matter (PM2.5) on male testosterone biosynthesis disruption

Exposure to PM2.5 is the most significant air pollutant for health risk. The testosterone level in male is vulnerable to environmental toxicants. In the past, researchers focused more attention on the impacts of PM2.5 on respiratory system, cardiovascular system, and nervous system, and few researchers focused attention on the reproductive system. Recent studies have reported that PM2.5 involved in male testosterone biosynthesis disruption, which is closely associated with male reproductive health. However, the underlying mechanisms by which PM2.5 causes testosterone biosynthesis disruption are still not clear. To better understand its potential mechanisms, we based on the existing scientific publications to critically and comprehensively reviewed the role and potential mechanisms of PM2.5 that are participated in testosterone biosynthesis in male. In this review, we summarized the potential mechanisms of PM2.5 triggering the change of testosterone level in male, which involve in oxidative stress, inflammatory response, ferroptosis, pyroptosis, autophagy and mitophagy, microRNAs (miRNAs), endoplasmic reticulum (ER) stress, and N6-methyladenosine (m6A) modification. It will provide new suggestions and ideas for prevention and treatment of testosterone biosynthesis disruption caused by PM2.5 for future research.

Non-coding RNAs: An emerging player in particulate matter 2.5-mediated toxicity

Exposure to air pollution has been connected to around seven million early deaths annually and also contributing to higher than 3 % of disability-adjusted lost life years. Particulate matters (PM) are among the key pollutants that directly discharged or formed due to atmospheric chemical interactions. Among these matters, due of its large surface area, PM2.5 may absorb a different harmful and toxic substances. One of the outcomes of such environmental disturbance is oxidative stress which affects cellular processes including apoptosis, inflammation, and epithelial mesenchymal transition. Non-coding RNAs (ncRNA) such as, miRNAs, lncRNAs, and circRNAs are classified as non-protein coding RNA's. Over the past few years these small molecules have been gaining so much attention since they participate in variety of physiological and pathological processes and their expression change during disease periods. Regarding epigenetic properties, ncRNAs play an important function in organism's response to environmental stimulus. In this manner, it was revealed that exposure to PM2.5 may cause epigenetic reprogramming, such as, ncRNAs signature's alteration, which can be effective concerning pathophysiology state. In this review, we describe PM2.5 impact on ncRNAs and excavate its roles in toxicity caused by PM2.5.

MitomiR-504 alleviates the copper-induced mitochondria-mediated apoptosis by suppressing Bak1 expression in porcine jejunal epithelial cells

Copper (Cu), an environmental heavy metal pollutant, has been widely researched in its toxicology. Recently, an increasing number of mitochondrial microRNAs (mitomiRs) have been shown to involve in the metabolic regulation. However, the underlying mechanisms of mitomiRs on regulating apoptosis under Cu exposure are still unclear. Here, we proved that Cu induced mitochondria-mediated apoptosis in porcine jejunal epithelial cells, concomitant with distinct reduction of mitomiR-504 in vivo and in vitro. The miR-504 mimic notably enhanced the mRNA and protein expressions of Bak1, Bax, Cleaved-caspase3 and Caspase-9, and significantly decreased the apoptosis rate and Bcl-2 mRNA and protein levels, indicating that overexpression of mitomiR-504 attenuated the Cu-induced mitochondria-mediated apoptosis. Besides, Bak1 was confirmed as a direct target of mitomiR-504 by the bioinformatics analysis and dual-luciferase reporter assay. Subsequently, transfection of siRNA targeting Bak1 significantly enhanced the alleviating effect of miR-504 mimic on the Cu-induced mitochondria-mediated apoptosis. Overall, these suggested that overexpression of mitomiR-504 alleviated the Cu-induced mitochondria-mediated apoptosis in jejunal epithelial cells by suppressing Bak1 expression. These findings are conducive to elucidating the mechanism of Cu-induced jejunal epithelial pathologies, providing a new research idea for the Cu toxicology.

The pathophysiological and molecular mechanisms of atmospheric PM2.5 affecting cardiovascular health: A review

BACKGROUND

Exposure to ambient fine particulate matter (PM2.5, with aerodynamic diameter less than 2.5 µm) is a leading environmental risk factor for global cardiovascular health concern.

OBJECTIVE

To provide a roadmap for those new to this field, we reviewed the new insights into the pathophysiological and cellular/molecular mechanisms of PM2.5 responsible for cardiovascular health.

MAIN FINDINGS

PM2.5 is able to disrupt multiple physiological barriers integrity and translocate into the systemic circulation and get access to a range of secondary target organs. An ever-growing body of epidemiological and controlled exposure studies has evidenced a causal relationship between PM2.5 exposure and cardiovascular morbidity and mortality. A variety of cellular and molecular biology mechanisms responsible for the detrimental cardiovascular outcomes attributable to PM2.5 exposure have been described, including metabolic activation, oxidative stress, genotoxicity, inflammation, dysregulation of Ca2+ signaling, disturbance of autophagy, and induction of apoptosis, by which PM2.5 exposure impacts the functions and fates of multiple target cells in cardiovascular system or related organs and further alters a series of pathophysiological processes, such as cardiac autonomic nervous system imbalance, increasing blood pressure, metabolic disorder, accelerated atherosclerosis and plaque vulnerability, platelet aggregation and thrombosis, and disruption in cardiac structure and function, ultimately leading to cardiovascular events and death. Therein, oxidative stress and inflammation were suggested to play pivotal roles in those pathophysiological processes.

CONCLUSION

Those biology mechanisms have deepen insights into the etiology, course, prevention and treatment of this public health concern, although the underlying mechanisms have not yet been entirely clarified.

MicroRNA-205-5p plays a suppressive role in the high-fat diet-induced atrial fibrosis through regulation of the EHMT2/IGFBP3 axis

Objective

MicroRNAs (miRNAs) targeting has been revealed to be an appealing strategy for the treatment and management of atrial fibrillation (AF). In this research, we aimed to explore the mechanisms of miR-205-5p in reducing the high-fat diet (HFD)-induced atrial fibrosis through the EHMT2/IGFBP3 axis.

Methods

Expression levels of miR-205-5p, IGFBP3 and EHMT2 were determined in AF patients, cell fibrosis models and mouse atrial fibrosis models. Luciferase activity and RIP assays were performed to detect the binding between miR-205-5p and EHMT2, and ChIP assays were implemented to detect the enrichment of H3K9me2 and H3K4me3 in the promoter region of IGFBP3 in cells. The related experiments focusing on the inflammatory response, atrial fibrosis, mitochondrial damage, and metabolic abnormalities were performed to figure out the roles of miR-205-5p, IGFBP3, and EHMT2 in cell and mouse atrial fibrosis models.

Results

Low expression levels of miR-205-5p and IGFBP3 and a high expression of EHMT2 were found in AF patients, cell fibrosis models and mouse atrial fibrosis models. Upregulation of miR-205-5p reduced the expression of TGF-β1, α-SMA, Col III and other fibrosis-related proteins. miR-205-5p overexpression targeted EHMT2 to regulate the methylation of H3 histones to promote IGFBP3 expression, which in turn affected the fibrosis of atrial muscle cells. In HFD-induced atrial fibrosis mice, upregulated miR-205-5p or elevated IGFBP3 alleviated atrial fibrosis, mitochondrial damage, and metabolic abnormalities.

Conclusion

This study suggests that miR-205-5p attenuates HFD-induced atrial fibrosis via modulating the EHMT2/IGFBP3 axis.

Graphical Abstract

miR-205-5p alleviates high-fat diet-induced atrial fibrosis in mice via EHMT2/IGFBP3.

A comprehensive understanding of ambient particulate matter and its components on the adverse health effects based from epidemiological and laboratory evidence

The impacts of air pollution on public health have become a great concern worldwide. Ambient particulate matter (PM) is a major air pollution that comprises a heterogeneous mixture of different particle sizes and chemical components. The chemical composition and physicochemical properties of PM change with space and time, which may cause different impairments. However, the mechanisms of the adverse effects of PM on various systems have not been fully elucidated and systematically integrated. The Adverse Outcome Pathway (AOP) framework was used to comprehensively illustrate the molecular mechanism of adverse effects of PM and its components, so as to clarify the causal mechanistic relationships of PM-triggered toxicity on various systems. The main conclusions and new insights of the correlation between public health and PM were discussed, especially at low concentrations, which points out the direction for further research in the future. With the deepening of the study on its toxicity mechanism, it was found that PM can still induce adverse health effects with low-dose exposure. And the recommended Air Quality Guideline level of PM_2.5 was adjusted to 5 μg/m³ by World Health Organization, which meant that deeper and more complex mechanisms needed to be explored. Traditionally, oxidative stress, inflammation, autophagy and apoptosis were considered the main mechanisms of harmful effects of PM. However, recent studies have identified several emerging mechanisms involved in the toxicity of PM, including pyroptosis, ferroptosis and epigenetic modifications. This review summarized the comprehensive evidence on the health effects of PM and the chemical components of it, as well as the combined toxicity of PM with other air pollutants. Based on the AOP Wiki and the mechanisms of PM-induced toxicity at different levels, we first constructed the PM-related AOP frameworks on various systems.

PM2.5-Induced Programmed Myocardial Cell Death via mPTP Opening Results in Deteriorated Cardiac Function in HFpEF Mice

PM2.5 exposure can induce or exacerbate heart failure and is associated with an increased risk of heart failure hospitalization and mortality; however, the underlying mechanisms remain unclear. This study focuses on the potential mechanisms underlying PM2.5 induction of cardiomyocyte programmed necrosis as well as its promotion of cardiac function impairment in a mouse model of heart failure with preserved ejection fraction (HFpEF). HFpEF mice were exposed to concentrated ambient PM2.5 (CAP) (CAP group) or filtered air (FA) (FA group) for 6 weeks. Changes in myocardial pathology and cardiac function were documented for comparisons between the two groups. In vitro experiments were performed to measure oxidative stress and mitochondrial permeability transition pore (mPTP) dynamics in H9C2 cells following 24 h exposure to PM2.5. Additionally, co-immunoprecipitation was conducted to detect p53 and cyclophilin D (CypD) interactions. The results showed exposure to CAP promoted cardiac function impairment in HFpEF mice. Myocardial pathology analysis and in vitro experiments demonstrated that PM2.5 led to mitochondrial damage in cardiomyocytes and, eventually, their necrosis. Moreover, our experiments also suggested that PM2.5 increases mitochondrial reactive oxygen species (ROS), induces DNA oxidative damage, and decreases the inner mitochondrial membrane potential (ΔΨm). This indicates the presence of mPTP opening. Co-immunoprecipitation results showed a p53/CypD interaction in the myocardial tissue of HFpEF mice in the CAP group. Inhibition of CypD by cyclosporin A was found to reverse PM2.5-induced mPTP opening and H9C2 cell death. In conclusion, PM2.5 induces mPTP opening to stimulate mitochondria-mediated programmed necrosis of cardiomyocytes, and it might exacerbate cardiac function impairment in HFpEF mice.

Identification of a circulating microRNAs biomarker panel for non-invasive diagnosis of coronary artery disease: case-control study

Background

Circulating microRNAs (miRNAs) are considered a hot spot of research that can be employed for monitoring and/or diagnostic purposes in coronary artery disease (CAD). Since different disease features might be reflected on altered profiles or plasma miRNAs concentrations, a combination of miRNAs can provide more reliable non-invasive biomarkers for CAD.

Subjects and methods

We investigated a panel of 14-miRNAs selected using bioinformatics databases and current literature searching for miRNAs involved in CAD using quantitative real-time PCR technique in 73 CAD patients compared to 73 controls followed by function and pathway enrichment analysis for the 14-miRNAs.

Results

Our results revealed three out of the 14 circulating miRNAs understudy; miRNAs miR133a, miR155 and miR208a were downregulated. While 11 miRNAs were up-regulated in a descending order from highest fold change to lowest: miR-182, miR-145, miR-21, miR-126, miR-200b, miR-146A, miR-205, miR-135b, miR-196b, miR-140b and, miR-223. The ROC curve analysis indicated that miR-145, miR-182, miR-133a and, miR-205 were excellent biomarkers with the highest AUCs as biomarkers in CAD. All miRNAs under study except miR-208 revealed a statistically significant relation with dyslipidemia. MiR-126 and miR-155 showed significance with BMI grade, while only miR-133a showed significance with the obese patients in general. MiR-135b and miR-140b showed a significant correlation with the Wall Motion Severity Index. Pathway enrichment analysis for the miRNAS understudy revealed pathways relevant to the fatty acid biosynthesis, ECM-receptor interaction, proteoglycans in cancer, and adherens junction.

Conclusion

The results of this study identified a differentially expressed circulating miRNAs signature that can discriminate CAD patients from normal subjects. These results provide new insights into the significant role of miRNAs expression associated with CAD pathogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02711-9.

Adverse outcome pathway of fine particulate matter leading to increased cardiovascular morbidity and mortality: An integrated perspective from toxicology and epidemiology

Fine particulate matter (PM_2.5) exposure is a major threat to public health, and is listed as one of the leading factors associated with global premature mortality. Among the adverse health effects on multiple organs or tissues, the influence of PM_2.5 exposure on cardiovascular system has drawn more and more attention. Although numerous studies have investigated the mechanisms responsible for the cardiovascular toxicity of PM_2.5, the various mechanisms have not been integrated due to the variety of the study models, different levels of toxicity assessment endpoints, etc. Adverse Outcome Pathway (AOP) framework is a useful tool to achieve this goal so as to facilitate comprehensive understanding of toxicity assessment of PM_2.5 on cardiovascular system. This review aims to illustrate the causal mechanistic relationships of PM_2.5-triggered cardiovascular toxicity from different levels (from molecular/cellular/organ to individual/population) by using AOP framework. Based on the AOP Wiki and published literature, we propose an AOP framework focusing on the cardiovascular toxicity induced by PM_2.5 exposure. The molecular initiating event (MIE) is identified as reactive oxygen species generation, followed by the key events (KEs) of oxidative damage and mitochondria dysfunction, which induces vascular endothelial dysfunction via vascular endothelial cell autophagy dysfunction, vascular fibrosis via vascular smooth muscle cell activation, cardiac dysregulation via myocardial apoptosis, and cardiac fibrosis via fibroblast proliferation and myofibroblast differentiation, respectively; all of the above cardiovascular injuries ultimately elevate cardiovascular morbidity and mortality in the general population. As far as we know, this is the first work on PM_2.5-related cardiovascular AOP construction. In the future, more work needs to be done to explore new markers in the safety assessment of cardiovascular toxicity induced by PM_2.5.

Study on Lung Injury Caused by Fine Particulate Matter and Intervention Effect of Rhodiola wallichiana

Objective

The objective of this study was to observe the protective effect of Rhodiola wallichiana drops in a rat model of fine particulate matter (PM2.5) lung injury.

Methods

Forty male Wistar rats were randomly divided into blank control (NC), normal saline (NS), PM2.5-infected (PM), and Rhodiola wallichiana (RW) groups. Rats in the NC group were not provided any interventions, whereas those in the NS and PM groups were administered normal saline and PM2.5 suspension by trachea drip once a week for four weeks. Rats in the RW group were intraperitoneally administered Rhodiola wallichiana for 14 days and then administered PM2.5 suspension by trachea drip 7 days after drug delivery. The levels of inflammatory factors such as interleukin-6, interleukin-1β, and tumor necrosis factor-alpha and oxidative stress biomarkers such as 8-hydroxy-2′-deoxyguanosine, 4-hydroxynonenal, and protein carbonyl content were determined in the serum and bronchoalveolar lavage fluid by ELISA. The level of 4-hydroxynonenal in the lung was also determined using Western blotting and immunohistochemical staining.

Results

Levels of inflammatory factors and oxidative stress biomarkers were all increased in the PM group but decreased in the RW group. Western blotting revealed increased 4-hydroxynonenal levels in the PM group but decreased levels in the RW group. Immunohistochemical staining also provided similar results.

Conclusion

Rhodiola wallichiana could protect rats from inflammation and oxidative stress injury caused by PM2.5.

Particulate Matter-Induced Acute Coronary Syndrome: MicroRNAs as Microregulators for Inflammatory Factors

The most prevalent cause of mortality and morbidity worldwide is acute coronary syndrome (ACS) and its consequences. Exposure to particulate matter (PM) from air pollution has been shown to impair both. Various plausible pathogenic mechanisms have been identified, including microRNAs (miRNAs), an epigenetic regulator for gene expression. Endogenous miRNAs, average 22-nucleotide RNAs (ribonucleic acid), regulate gene expression through mRNA cleavage or translation repression and can influence proinflammatory gene expression posttranscriptionally. However, little is known about miRNA responses to fine PM (PM_2.5, PM₁₀, ultrafine particles, black carbon, and polycyclic aromatic hydrocarbon) from air pollution and their potential contribution to cardiovascular consequences, including systemic inflammation regulation. For the past decades, microRNAs (miRNAs) have emerged as novel, prospective diagnostic and prognostic biomarkers in various illnesses, including ACS. We wanted to outline some of the most important studies in the field and address the possible utility of miRNAs in regulating particulate matter-induced ACS (PMIA) on inflammatory factors in this review.

Tissue-Protective Effect of Erdosteine on Multiple-Organ Injuries Induced by Fine Particulate Matter

Background

Fine particulate matter (PM2.5) is the air pollutant that most threatens global public health. The purpose of this study was to observe the inflammatory and oxidative stress injury of multiple organs induced by PM2.5 in rats and to explore the tissue-protective effect of erdosteine.

Material/Methods

We randomly divided 40 male Wistar rats into a blank control group, a saline group, a PM2.5 exposure group, and an erdosteine intervention group. We assessed changes in organs tissue homogenate and biomarkers of inflammation and oxidative stress in serum and bronchoalveolar lavage fluid (BALF).

Results

(1) The expressions of IL-6, IL-1β, TNF-α, 8-OHdG, 4-HNE, and PCC in serum and BALF of the PM2.5 exposure group increased, but decreased after treatment with erdosteine, suggesting that erdosteine treatment attenuates inflammatory and oxidative stress injury. (2) The expression of γ-GCS in serum and lungs in the PM2.5 exposure group increased, but did not change significantly after treatment with erdosteine. This suggests that PM2.5 upregulates the level of γ-GCS, while erdosteine does not affect this protective response. (3) The expression of T-AOC in serum, lungs, spleens, and kidneys of the PM2.5 exposure group decreased, but increased after treatment with erdosteine. Our results suggest that PM2.5 can cause imbalance of oxidation/anti-oxidation in multiple organs, and erdosteine can alleviate this imbalance.

Conclusions

PM2.5 exposure can lead to inflammatory and oxidative stress damage in serum and organ tissues of rats. Erdosteine may be an effective anti-inflammatory and antioxidant that can reduce this injury.

The expression profiling of microRNA in systemic sclerosis-associated pulmonary arterial hypertension

Background

The role of microRNAs (miRNAs) in the pathogenesis of systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) remains to be fully elucidated. This study evaluated the expression profile of miRNAs in the lung tissue of patients with SSc-PAH.

Methods

Lung tissue samples were collected from 3 SSc-PAH patients and 4 healthy controls. A small RNA high throughput sequence approach was used for screening the differentially expressed miRNAs in the lung tissue samples. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate 4 highly significant differentially expressed miRNAs. Gene Ontology and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis for mRNAs were performed using the R package clusterProfiler software.

Results

A total of 82 upregulated miRNAs and 35 downregulated miRNAs were detected in the lung tissues of patients with SSc-PAH compared with healthy controls. GO enrichment analysis demonstrated that the upregulated target genes were closely involved in biological processes such as nervous system development, anatomical structure morphogenesis, system development, cellular macromolecule metabolic processes, and cellular processes. The downregulated target genes were involved in the plasma membrane bound cell projection morphogenesis and the regulation of macromolecule metabolic processes. The KEGG enrichment analysis showed that the upregulated genes were associated with important pathways involved in cancer biology, and the target genes of the downregulated miRNAs were involved in axon guidance. High throughput sequencing and qRT-PCR revealed that hsa-miR-205-5p and hsa-miR-539-3p were differentially expressed in SSc-PAH tissue. The target genes of hsa-miR-205-5p and hsa-miR-539-3p, IRF1and ADCYAP1, respectively, were verified using the high throughput dataset GSE48149.

Conclusions

miRNAs may play an important role in the pathogenesis of SSc-PAH, and hsa-miR-205-5p and hsa-miR-539-3p may be potential therapeutic targets in patients with SSc-PAH.

Dexmedetomidine inhibits inflammatory response and oxidative stress through regulating miR-205-5p by targeting HMGB1 in cerebral ischemic/reperfusion

OBJECTIVE

To investigate effects of dexmedetomidine (DEX) on miR-205-5p/HMGB1 axis in cerebral ischemic/reperfusion (I/R) injury.

METHODS

Both in vivo I/R rat model and in vitro hypoxia/reoxygenation (H/R) cell model using rat hippocampal neurons cells were established. miR-205-5p was overexpressed or inhibited by transfection of miR-205-5p mimics or inhibitor. HMGB1 was overexpressed by transfection overexpression plasmids (OE-HMGB1). TTC staining was used for measurement of infraction volume. Oxidative stress was evaluated by measurement of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) and inflammation was evaluated by measurement of IL-1β, IL-6 and TNF-α. Dual luciferase reporter assay was performed to confirm binding between miR-205-5p and HMGB1. The expression levels of miR-205-5p, and HMGB1 were measured using RT-qPCR. Western blotting was used to test the protein expression levels of HMGB1, nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase (GPx), glutathione reductase (GR), heme oxygenase 1 (HO-1) and catalase (CAT).

RESULTS

Treatment of DEX significantly reduced brain infraction volume, decreased Longa's neurological function score and inhibited oxidative stress and inflammation in brain tissues of I/R rats, which were all reversed by inhibition of miR-205-5p. Both treatment of DEX or overexpression of miR-205-5p restricted oxidative stress and inflammation in H/R rat hippocampal neurons cells. The inhibition of miR-205-5p reversed the effects of DEX, while the overexpression of HMGB1 reversed the effects of miR-205-5p overexpression in H/R rat hippocampal neurons cells. Dual luciferase reporter assay showed miR-205-5p directly targeted HMGB1.

CONCLUSION

DEX improved I/R injury by suppressing brain oxidative stress and inflammation DEX improved I/R injury by suppressing brain oxidative stress and inflammation through activating miR-205-5p/HMGB1 axis through activating miR-205-5p/HMGB1 axis.

Inhibiting miR-205 Alleviates Cardiac Ischemia/Reperfusion Injury by Regulating Oxidative Stress, Mitochondrial Function, and Apoptosis

BACKGROUND

miR-205 is important for oxidative stress, mitochondrial dysfunction, and apoptosis. The roles of miR-205 in cardiac ischemia/reperfusion (I/R) injury remain unknown. The aim of this research is to reveal whether miR-205 could regulate cardiac I/R injury by focusing upon the oxidative stress, mitochondrial function, and apoptosis.

METHODS

Levels of miR-205 and Rnd3 were examined in the hearts with I/R injury. Myocardial infarct size, cardiac function, oxidative stress, mitochondria function, and cardiomyocyte apoptosis were detected in mice with myocardial ischemia/reperfusion (MI/R) injury. The primary neonatal cardiomyocytes underwent hypoxia/reoxygenation (H/R) to simulate MI/R injury.

RESULTS

miR-205 levels were significantly elevated in cardiac tissues from I/R in comparison with those from Sham. In comparison with controls, levels of Rnd3 were significantly decreased in the hearts from mice with MI/R injury. Furthermore, inhibiting miR-205 alleviated MI/R-induced apoptosis, reduced infarct size, prevented oxidative stress increase and mitochondrial fragmentation, and improved mitochondrial functional capacity and cardiac function. Consistently, overexpression of miR-205 increased infarct size and promoted apoptosis, oxidative stress, and mitochondrial dysfunction in mice with MI/R injury. In cultured mouse neonatal cardiomyocytes, downregulation of miR-205 reduced oxidative stress in H/R-treated cardiomyocytes. Finally, inhibiting Rnd3 ablated the cardioprotective effects of miR-205 inhibitor in MI/R injury.

CONCLUSIONS

We conclude that inhibiting miR-205 reduces infarct size, improves cardiac function, and suppresses oxidative stress, mitochondrial dysfunction, and apoptosis by promoting Rnd3 in MI/R injury. miR-205 inhibitor-induced Rnd3 activation is a valid target to treat MI/R injury.