Mettl14 mediates the inflammatory response of macrophages in atherosclerosis through the NF-κB/IL-6 signaling pathway

The m6A eraser FTO suppresses ferroptosis via mediating ACSL4 in LPS-induced macrophage inflammation

Acute lung injury (ALI) is a serious disorder characterized by the release of pro-inflammatory cytokines and cascade activation of macrophages. Ferroptosis, a form of iron-dependent cell death triggered by intracellular phospholipid peroxidation, has been implicated as an internal mechanism underlying ALI. In this study, we investigated the effects of m6A demethylase fat mass and obesity-associated protein (FTO) on the inhibition of macrophage ferroptosis in ALI. Using a mouse model of lipopolysaccharide (LPS)-induced ALI, we observed the induction of ferroptosis and its co-localization with the macrophage marker F4/80, suggesting that ferroptosis might be induced in macrophages. Ferroptosis was promoted during LPS-induced inflammation in macrophages in vitro, and the inflammation was counteracted by the ferroptosis inhibitor ferrostatin-1 (fer-1). Given that FTO showed lower expression levels in the lung tissue of mice with ALI and inflammatory macrophages, we further dissected the regulatory capacity of FTO in ferroptosis. The results demonstrated that FTO alleviated macrophage inflammation by inhibiting ferroptosis. Mechanistically, FTO decreased the stability of ACSL4 mRNA via YTHDF1, subsequently inhibiting ferroptosis and inflammation by interrupting polyunsaturated fatty acid consumption. Moreover, FTO downregulated the synthesis and secretion of prostaglandin E2, thereby reducing ferroptosis and inflammation. In vivo, the FTO inhibitor FB23-2 aggravated lung injury, the inflammatory response, and ferroptosis in mice with ALI; however, fer-1 therapy mitigated these effects. Overall, our findings revealed that FTO may function as an inhibitor of the inflammatory response driven by ferroptosis, emphasizing its potential as a target for ALI treatment.

Unravelling the Impact of RNA Methylation Genetic and Epigenetic Machinery in the Treatment of Cardiomyopathy

Cardiomyopathy (CM) represents a heterogeneous group of diseases primarily affecting cardiac structure and function, with genetic and epigenetic dysregulation playing a pivotal role in its pathogenesis. Emerging evidence from the burgeoning field of epitranscriptomics has brought to light the significant impact of various RNA modifications, notably N6-methyladenosine (m6A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N1-methyladenosine (m1A), 2'-O-methylation (Nm), and 6,2'-O-dimethyladenosine (m6Am), on cardiomyocyte function and the broader processes of cardiac and vascular remodelling. These modifications have been shown to influence key pathological mechanisms including mitochondrial dysfunction, oxidative stress, cardiomyocyte apoptosis, inflammation, immune response, and myocardial fibrosis. Importantly, aberrations in the RNA methylation machinery have been observed in human CM cases and animal models, highlighting the critical role of RNA methylating enzymes and their potential as therapeutic targets or biomarkers for CM. This review underscores the necessity for a deeper understanding of RNA methylation processes in the context of CM, to illuminate novel therapeutic avenues and diagnostic tools, thereby addressing a significant gap in the current management strategies for this complex disease.

m6A mRNA methylation-mediated MAPK signaling modulates the nasal mucosa inflammatory response in allergic rhinitis

Background

Allergic rhinitis (AR) is a complex disease in which gene-environment interactions contribute to its pathogenesis. Epigenetic modifications, such as N6-methyladenosine (m6A) modification of mRNA, play important roles in regulating gene expression in multiple physiological and pathological processes. However, the function of m6A modification in AR and the inflammatory response is poorly understood.

Methods

We used the ovalbumin (OVA) and aluminum hydroxide to induce an AR mouse model. Nasal symptoms, histopathology, and serum cytokines were examined. We performed combined m6A and RNA sequencing to analyze changes in m6A modification profiles. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and methylated RNA immunoprecipitation sequencing qPCR (MeRIP-qPCR) were used to verify differential methylation of mRNAs and the m6A methylation level. Knockdown or inhibition of Alkbh5 in nasal mucosa of mice was mediated by lentiviral infection or IOX1 treatment.

Results

We showed that m6A was enriched in a group of genes involved in MAPK signaling pathway. Moreover, we identified a MAPK pathway involving Map3k8, Erk2, and Nfκb1 that may play a role in the disrupted inflammatory response associated with nasal inflammation. The m6A eraser, Alkbh5, was highly expressed in the nasal mucosa of AR model mice. Furthermore, knockdown of Alkbh5 expression by lentiviral infection resulted in high MAPK pathway activity and a significant nasal mucosa inflammatory response. Our findings indicate that ALKBH5-mediated m6A dysregulation likely contributes to a nasal inflammatory response via the MAPK pathway.

Conclusion

Together, our data show that m6A dysregulation mediated by ALKBH5, is likely to contribute to inflammation of the nasal mucosa via the MAPK signaling pathway, suggesting that ALKBH5 is a potential biomarker for AR treatment.

Methyltransferase like-14 suppresses growth and metastasis of non-small-cell lung cancer by decreasing LINC02747

Multiple epigenetic regulatory mechanisms exert critical roles in tumor development, and understanding the interactions and impact of diverse epigenetic modifications on gene expression in cancer is crucial for the development of precision medicine. We found that methyltransferase-like 14 (METTL14) was significantly downregulated in non-small-cell lung cancer (NSCLC) tissues. Functional experiments demonstrated that overexpression of METTL14 inhibited the proliferation and migration of NSCLC cells both in vivo and in vitro, and the colorimetric m6A quantification assay also showed that knockdown of METTL14 notably reduced global m6A modification levels in NSCLC cells. By using the methylated-RNA immunoprecipitation-qPCR and dual-luciferase reporter assays, we verified that long noncoding RNA LINC02747 was a target of METTL14 and was regulated by METTL14-mediated m6A modification, and silencing LINC02747 inhibited the malignant progression of NSCLC by modulating the PI3K/Akt and CDK4/Cyclin D1 signaling pathway. Further studies revealed that overexpression of METTL14 promoted m6A methylation and accelerated the decay of LINC02747 mRNA via increased recognition of the "GAACU" binding site by YTHDC2. Additionally, histone demethylase lysine-specific histone demethylase 5B (KDM5B) mediated the demethylation of histone H3 lysine 4 tri-methylation (H3K4me3) in the METTL14 promoter region and repressed its transcription. In summary, KDM5B downregulated METTL14 expression at the transcriptional level in a H3K4me3-dependent manner, while METTL14 modulated LINC02747 expression via m6A modification. Our results demonstrate a synergy of multiple mechanisms in regulating the malignant phenotype of NSCLC, revealing the complex regulation involved in the occurrence and development of cancer.

m6A epitranscriptomic modification of inflammation in cardiovascular disease

Cardiovascular disease is currently the number one cause of death endangering human health. There is currently a large body of research showing that the development of cardiovascular disease and its complications is often accompanied by inflammatory processes. In recent years, epitranscriptional modifications have been shown to be involved in regulating the pathophysiological development of inflammation in cardiovascular diseases, with 6-methyladenine being one of the most common RNA transcriptional modifications. In this review, we link different cardiovascular diseases, including atherosclerosis, heart failure, myocardial infarction, and myocardial ischemia-reperfusion, with inflammation and describe the regulatory processes involved in RNA methylation. Advances in RNA methylation research have revealed the close relationship between the regulation of transcriptome modifications and inflammation in cardiovascular diseases and brought potential therapeutic targets for disease diagnosis and treatment. At the same time, we also discussed different cell aspects. In addition, in the article we also describe the different application aspects and clinical pathways of RNA methylation therapy. In summary, this article reviews the mechanism, regulation and disease treatment effects of m6A modification on inflammation and inflammatory cells in cardiovascular diseases in recent years. We will discuss issues facing the field and new opportunities that may be the focus of future research.

MLKL deficiency alleviates acute alcoholic liver injury via inhibition of NLRP3 inflammasome

Mixed lineage kinase domain-like protein (MLKL) is identified as the terminal executor of necroptosis. However, its role in acute alcoholic liver injury remains unclear. This study elucidates that MLKL can contribute to acute alcoholic liver injury independently of necroptosis. Although the expression of MLKL was upregulated, no significant increase in its phosphorylation or membrane translocation was observed in the liver tissues of mice treated with ethanol. This finding confirms that alcohol intake does not induce necroptosis in mouse liver tissue. Additionally, the deletion of Mlkl resulted in the downregulation of NLRP3 expression, which subsequently inhibited the activation of the NLRP3 inflammasome and the ensuing inflammatory response, thereby effectively mitigating liver injury induced by acute alcohol consumption. The knockout of Nlrp3 did not affect the expression of MLKL, further confirming that MLKL acts upstream of NLRP3. Mechanistically, inhibiting the nuclear translocation of MLKL reduced the nuclear entry of p65, the principal transcriptional regulator of NLRP3, thereby limiting the transcription of Nlrp3 mRNA and subsequent NLRP3 expression. Overall, this study unveils a novel mechanism of MLKL regulates the activation of NLRP3 inflammasomes in a necroptosis independent way in acute alcoholic liver injury.

Deciphering m6A methylation in monocyte-mediated cardiac fibrosis and monocyte-hitchhiked erythrocyte microvesicle biohybrid therapy

Rationale: Device implantation frequently triggers cardiac remodeling and fibrosis, with monocyte-driven inflammatory responses precipitating arrhythmias. This study investigates the role of m6A modification enzymes METTL3 and METTL14 in these responses and explores a novel therapeutic strategy targeting these modifications to mitigate cardiac remodeling and fibrosis. Methods: Peripheral blood mononuclear cells (PBMCs) were collected from patients with ventricular septal defects (VSD) who developed conduction blocks post-occluder implantation. The expression of METTL3 and METTL14 in PBMCs was measured. METTL3 and METTL14 deficiencies were induced to evaluate their effect on angiotensin II (Ang II)-induced myocardial inflammation and fibrosis. m6A modifications were analyzed using methylated RNA immunoprecipitation followed by quantitative PCR. NF-κB pathway activity and levels of monocyte migration and fibrogenesis markers (CXCR2 and TGF-β1) were assessed. An erythrocyte microvesicle-based nanomedicine delivery system was developed to target activated monocytes, utilizing the METTL3 inhibitor STM2457. Cardiac function was evaluated via echocardiography. Results: Significant upregulation of METTL3 and METTL14 was observed in PBMCs from patients with VSD occluder implantation-associated persistent conduction block. Deficiencies in METTL3 and METTL14 significantly reduced Ang II-induced myocardial inflammation and fibrosis by decreasing m6A modification on MyD88 and TGF-β1 mRNAs. This disruption reduced NF-κB pathway activation, lowered CXCR2 and TGF-β1 levels, attenuated monocyte migration and fibrogenesis, and alleviated cardiac remodeling. The erythrocyte microvesicle-based nanomedicine delivery system effectively targeted inflamed cardiac tissue, reducing inflammation and fibrosis and improving cardiac function. Conclusion: Inhibiting METTL3 and METTL14 in monocytes disrupts the NF-κB feedback loop, decreases monocyte migration and fibrogenesis, and improves cardiac function. Targeting m6A modifications of monocytes with STM2457, delivered via erythrocyte microvesicles, reduces inflammation and fibrosis, offering a promising therapeutic strategy for cardiac remodeling associated with device implantation.

m6A RNA methylation: The latent string-puller in fibrosis

Fibrosis is a pathological phenomenon characterized by the aberrant accumulation of extracellular matrix (ECM) in tissues. Fibrosis is a universally age-related disease involving that many organs and is the final stage of many chronic inflammatory diseases, which often threaten the patient's health. Undoubtedly, fibrosis has become a serious economic and health burden worldwide, However, the pathogenesis of fibrosis is complex. Further, the key molecules still remain to be unraveled. Hence, so far, there have been no effective treatments designed against the key targets of fibrosis. The methylation modification on the nitrogen atom at position 6 of adenine (m6A) is the most common mRNA modification in mammals. There is increasing evidence that m6A is actively involved in the pathogenesis of fibrosis. This review aims to highlight m6A-associated mechanisms and functions in several organic fibrosis, which implies that m6A is universal and critical for fibrosis and summarize the outlook of m6A in the treatment of fibrosis. This may light up the unknown aspects of this condition for researchers interested to explore fibrosis further.

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Meta-analysis and transcriptomic analysis reveal that NKRF and ZBTB17 regulate the NF-κB signaling pathway, contributing to the shared molecular mechanisms of Alzheimer's disease and atherosclerosis

INTRODUCTION

Alzheimer's disease (AD) and atherosclerosis (AS) are widespread diseases predominantly observed in the elderly population. Despite their prevalence, the underlying molecular interconnections between these two conditions are not well understood.

METHODS

Utilizing meta-analysis, bioinformatics methodologies, and the GEO database, we systematically analyzed transcriptome data to pinpoint key genes concurrently differentially expressed in AD and AS. Our experimental validations in mouse models highlighted the prominence of two genes, NKRF (NF-κB-repressing factor) and ZBTB17 (MYC-interacting zinc-finger protein 1).

RESULTS

These genes appear to influence the progression of both AD and AS by modulating the NF-κB signaling pathway, as confirmed through subsequent in vitro and in vivo studies.

CONCLUSIONS

This research uncovers a novel shared molecular pathway between AD and AS, underscoring the significant roles of NKRF and ZBTB17 in the pathogenesis of these disorders.

Engineered M2 macrophage-derived extracellular vesicles with platelet membrane fusion for targeted therapy of atherosclerosis

Atherosclerosis is featured as chronic low-grade inflammation in the arteries, which leads to the formation of plaques rich in lipids. M2 macrophage-derived extracellular vesicles (M2EV) have significant potential for anti-atherosclerotic therapy. However, their therapeutic effectiveness has been hindered by their limited targeting capability in vivo. The objective of this study was to create the P-M2EV (platelet membrane-modified M2EV) using the membrane fusion technique in order to imitate the interaction between platelets and macrophages. P-M2EV exhibited excellent physicochemical properties, and microRNA (miRNA)-sequencing revealed that the extrusion process had no detrimental effects on miRNAs carried by the nanocarriers. Remarkably, miR-99a-5p was identified as the miRNA with the highest expression level, which targeted the mRNA of Homeobox A1 (HOXA1) and effectively suppressed the formation of foam cells in vitro. In an atherosclerotic low-density lipoprotein receptor-deficient (Ldlr-/-) mouse model, the intravenous injection of P-M2EV showed enhanced targeting and greater infiltration into atherosclerotic plaques compared to regular extracellular vesicles. Crucially, P-M2EV successfully suppressed the progression of atherosclerosis without causing systemic toxicity. The findings demonstrated a biomimetic platelet-mimic system that holds great promise for the treatment of atherosclerosis in clinical settings.

Muscone inhibits the progression of atherosclerotic plaques in mice aorta by inhibiting the NF-κB/p65 pathway

Atherosclerosis (AS) is considered to be one of the main pathogenic factors of coronary heart disease, cerebral infarction and peripheral vascular disease. Oxidative stress and inflammation run through the occurrence and development of atherosclerosis and related cardiovascular events. Muscone is a natural extract of deer musk and also the main physiological active substance of musk. This study investigated the impact of muscone on atherosclerosis. ApoE-/- mice were used to establised AS model and injected with low-dose (4 mg/kg/day) or high-dose (8 mg/kg/day) of muscone intraperitoneally for 4 weeks. Then aortic tissues were collected, and pathological sections of the aorta were prepared for oil red staining, HE and masson staining. The changes of MDA, SOD, VCAM-1, NF-κB, and TNF-α were observed by Western blotting or immunofluorescence staining. The results showed that high-dose muscone could effectively reduce the plaque area/aortic root area and relative atherosclerotic area, reduce the collagen composition in plaque tissue. In addition, we also found that high-dose muscone can effectively increase MDA level, reduce the level of SOD, and inhibit the expression of VCAM-1, NF-κB/p65, TNF-α in arterial plaques. Our results indicate that the administration of muscone has the benefit of inhibiting atherosclerosis. The potential mechanisms may be associated with antioxidant effect and inhibition of inflammatory reaction in arterial plaques. With the increasing understanding of the relationship between muscone and atherosclerosis, muscone has high potential value as a new drug to treat atherosclerosis.

The regulatory role of m6A methylation modification in metabolic syndrome pathogenesis and progression

Metabolic syndromes are characterized by various complications caused by disrupted glucose and lipid metabolism, which are major factors affecting the health of a population. However, existing diagnostic and treatment strategies have limitations, such as the lack of early diagnostic and therapeutic approaches, variability in patient responses to treatment, and cost-effectiveness. Therefore, developing alternative solutions for metabolic syndromes is crucial. N6-methyladenosine (m6A) is one of the most abundant modifications that determine the fate of RNA. m6A modifications are closely associated with metabolic syndrome development and present novel prospects for clinical applications. Aberrant m6A modifications have been detected during inflammatory infiltration, apoptosis, autophagy, iron sagging, necrosis, and scorching during metabolic syndrome pathogenesis and progression. However, few reviews have systematically described the correlation between m6A modifications and these factors concerning metabolic syndrome pathogenesis and progression. This study summarizes the m6A methylation regulators and their roles in metabolic syndrome development, highlighting the potential of m6A modification as a biomarker in metabolic disorders.

N6-methyladenosine modification in ischemic stroke: Functions, regulation, and therapeutic potential

N6-methyladenosine (m6A) modification is the most frequently occurring internal modification in eukaryotic RNAs. By modulating various aspects of the RNA life cycle, it has been implicated in a wide range of pathological and physiological processes associated with human diseases. Ischemic stroke is a major cause of death and disability worldwide with few treatment options and a narrow therapeutic window, and accumulating evidence has indicated the involvement of m6A modifications in the development and progression of this type of stroke. In this review, which provides insights for the prevention and clinical treatment of stroke, we present an overview of the roles played by m6A modification in ischemic stroke from three main perspectives: (1) the association of m6A modification with established risk factors for stroke, including hypertension, diabetes mellitus, hyperlipidemia, obesity, and heart disease; (2) the roles of m6A modification regulators and their functional regulation in the pathophysiological injury mechanisms of stroke, namely oxidative stress, mitochondrial dysfunction, endothelial dysfunction, neuroinflammation, and cell death processes; and (3) the diagnostic and therapeutic potential of m6A regulators in the treatment of stroke.

METTL14 depletion ameliorates ferroptosis in severe acute pancreatitis by increasing the N6-methyladenosine modification of ACSL4 and STA1

Methyltransferase-like 14 (METTL14) is implicated in the regulation of various inflammatory disorders. However, its function and molecular mechanism in severe acute pancreatitis (SAP) remains unrevealed. Here we reported an increase in METTL14 in the pancreas of SAP mice and cerulein-LPS-treated AR42J cells. METTL14 depletion reversed inflammatory response and ferroptosis by reducing the expression of SAT1 (spermidine/spermine N1-acetyltransferase 1) and ACSL4 (acyl-CoA synthetase long chain family member 4) in an m6A-dependent manner. IGF2BP2 (insulin like growth factor 2 mRNA binding protein 2) could recognize m6A-modified SAT1 and ACSL4 mRNA and enhance their stability. Moreover, METTL14 depletion ameliorated pancreatic injury, inflammation, and ferroptosis induced by SAP. METTL14 overexpression aggravated SAP by promoting ferroptosis in vivo. Therefore, these results demonstrated that METTL14-induced ferroptosis promoted the progression of SAP, and targeting METTL14 or ferroptosis could be a potential strategy for the prevention and treatment of SAP.

Remimazolam attenuates myocardial ischemia-reperfusion injury by inhibiting the NF-ĸB pathway of macrophage inflammation

BACKGROUND

Inflammation is a major contributing factor in myocardial ischemia/reperfusion (I/R) injury, and targeting macrophage inflammation is an effective strategy for myocardial I/R therapy. Though remimazolam is approved for sedation, induction, and the maintenance of general anesthesia in cardiac surgery, its effect on cardiac function during the perioperative period has not been reported. Therefore, this research aimed to explore the impact of remimazolam on inflammation during myocardial ischemia/reperfusion (I/R) injury.

METHODS

An in vivo myocardial I/R mice model and an in vitro macrophage inflammation model were used to confirm remimazolam's cardiac protective effect. In vivo, we used echocardiography, hematoxylin and eosin (HE), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining to determine remimazolam's therapeutic effects on myocardial I/R injury and inflammation. In vitro, we employed enzyme-linked immunosorbent assay (ELISA), Western blot, Real-time Quantitative PCR (qPCR), flow cytometry, and immunofluorescence staining to assess inflammatory responses, especially remimazolam's effects on macrophage polarization after I/R. Furthermore, molecular docking was used to identify its potential binding targets on the inflammatory pathway to explore the mechanism of remimazolam.

RESULTS

Remimazolam exhibited significant anti-myocardial I/R injury activity by inhibiting macrophage-mediated inflammation to reduce myocardial infarction, enhancing cardiac function. In addition, macrophage depletion counteracted improved cardiac function by remimazolam treatment. Mechanistically, the activated NF-ĸB signaling pathway and phosphorylation of p50 and p65 were repressed for anti-inflammatory effect. Consistently, two binding sites on p50 and p65 were identified by molecular docking to affect their phosphorylation of the Ser, Arg, Asp, and His residues, thus regulating NF-κB pathway activity.

CONCLUSION

Our results unveil the therapeutic potential of remimazolam against myocardial I/R injury by inhibiting macrophages polarizing into the M1 type, alleviating inflammation.

Identification of significant m6A regulators and immune microenvironment characterization in ischemic stroke

The role of m6A modification in the regulation of the immune microenvironment (IME) of ischemic stroke (IS) is barely known. Thus, we aim to investigate the impact of m6A modification on the IME of IS and its diagnostic value in IS. We comprehensively assessed the m6A modification patterns, the relationship between these modification patterns and the characteristics of the IME. The m6A modification patterns of individual IS sample were quantified by m6Ascore. The performance of m6A phenotype-related genes as potential biomarkers was evaluated by the area under the receiver operating characteristic curve. Experimental validation was also performed by qRT-PCR. Six dysregulated m6A regulators were identified and a classification model consisting of four key m6A regulators (METLL3, RBMX, RBM15B, YTDHF3) could distinguish IS and healthy control samples well. METTL3 and YTHDF3 are closely related to circulating neutrophil abundance. Two distinct m6A modification patterns were determined which differed in immunocyte abundance. We also identified six m6A phenotype-related genes (APOBEC3A, PTMA, FCGR3A, LOC440926, LOC649946, and FTH1L11), and further explored their biological function. Among them, APOBEC3A, FCGR3A, and FTH1L11 were positively associated with neutrophil abundance. APOBEC3A and FCGR3A were stable diagnostic m6A-associated genes in both the discovery and validation cohorts. This study reveals that m6A modification plays a non-negligible role in the formation of a diversified and complex IME in IS. The m6A phenotype-related genes could be diagnostic biomarkers of IS.

Update on N6-methyladenosine methylation in obesity-related diseases

Obesity is a chronic metabolic disease that is closely related to type 2 diabetes mellitus, cardiovascular diseases, nonalcoholic fatty liver disease, obstructive sleep apnea, and osteoarthritis. The prevalence of obesity is increasing rapidly every year and is recognized as a global public health problem. In recent years, the role of epigenetics in the development of obesity and related diseases has been recognized and is currently a research hotspot. N6-methyladenosine (m6A) methylation is the most abundant epigenetic modification in the eukaryotic RNA, including mRNA and noncoding RNA. Several studies have shown that the m6A modifications in the target mRNA and the corresponding m6A regulators play a significant role in lipid metabolism and are strongly associated with the pathogenesis of obesity-related diseases. In this review, the latest research findings regarding the role of m6A methylation in obesity and related metabolic diseases are summarized. The authors' aim is to highlight evidence that suggests the clinical utility of m6A modifications and the m6A regulators as novel early prediction biomarkers and precision therapeutics for obesity and obesity-related diseases.

METTL14 promotes IL-6-induced viability, glycolysis and inflammation in HaCaT cells via the m6A modification of TRIM27

Interleukin-6 (IL-6) is a cytokine generated by healthy constituents of the skin, but is also up-regulated by a wide range of skin lesions and inflammatory conditions to trigger cytopathy of skin cells. TRIM27 was identified to contribute to the functional effects of IL-6 on skin cells. However, the underlying mechanism was not clear. Lentivirus infection was used for gene overexpression or silencing. RT-PCR and Western blot were used to respectively assess mRNA and protein levels. Cell viability was assessed by CCK-8 assay. Extracellular flux analysis was used to assess the levels of oxygen consumption rate and extracellular acidification rate. Mouse back skin was treated with imiquimod to produce psoriasis-like inflammation in vivo. Histological assessment and immunohistochemistry staining were respectively applied to analyse lesioned mouse and human skin samples. IL-6-induced increased viability, glycolysis and inflammation in keratinocytes was inhibited both by a chemical methylation inhibitor and by METTL14 knockdown. Further investigation found that METTL14 induces m6A methylation of TRIM27, which is recognized by a m6A reader, IGF2BP2. Elevation of TRIM27 level and activation of IL-6/STAT3 signalling pathway were found in an in vivo psoriasis-like inflammation model, whereas inhibition m6A methylation strongly alleviated the inflammation. Finally, METTL14, TRIM27, STAT3, p-STAT3 and IL-6 expressions were all found to be increased in clinical skin samples of psoriatic patients. Our results unravelled METTL14/TRIM27/IGF2BP2 signalling axis in keratinocyte cytopathy, which plays a critical role in facilitating the activation of IL-6/STAT3 signalling pathway. Our findings should provide inspirations for the design of new therapeutics for skin inflammatory diseases including psoriasis.

Exploration and bioinformatic prediction for profile of mRNA bound to circular RNA BTBD7_hsa_circ_0000563 in coronary artery disease

BACKGROUND

As a novel circRNA, BTBD7_hsa_circ_0000563 has not been fully investigated in coronary artery disease (CAD). Our aim is to reveal the possible functional role and regulatory pathway of BTBD7_hsa_circ_0000563 in CAD via exploring genes combined with BTBD7_hsa_circ_0000563.

METHODS

A total of 45 peripheral blood mononuclear cell (PBMC) samples of CAD patients were enrolled. The ChIRP-RNAseq assay was performed to directly explore genes bound to BTBD7_hsa_circ_0000563. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were conducted to reveal possible functions of these genes. The interaction network was constructed by the STRING database and the Cytoscape software. The Cytoscape software were used again to identify clusters and hub genes of genes bound to BTBD7_hsa_circ_0000563. The target miRNAs of hub genes were predicted via online databases.

RESULTS

In this study, a total of 221 mRNAs directly bound to BTBD7_hsa_circ_0000563 were identified in PBMCs of CAD patients via ChIRP-RNAseq. The functional enrichment analysis revealed that these mRNAs may participate in translation and necroptosis. Moreover, the interaction network showed that there may be a close relationship between these mRNAs. Eight clusters can be further subdivided from the interaction network. RPS3 and RPSA were identified as hub genes and hsa-miR-493-5p was predicted to be the target miRNA of RPS3.

CONCLUSIONS

BTBD7_hsa_circ_0000563 and mRNAs directly bound to it may influence the initiation and progression of CAD, among which RPS3 and RPSA may be hub genes. These findings may provide innovative ideas for further research on CAD.

METTL14 contributes to acute lung injury by stabilizing NLRP3 expression in an IGF2BP2-dependent manner

Acute lung injury (ALI) as well as its more severe form, acute respiratory distress syndrome (ARDS), frequently leads to an uncontrolled inflammatory response. N6-methyladenosine (m6A) modification was associated with the progression of several inflammatory diseases. However, the role of methyltransferase-like 14 (METTL14)-mediated m6A methylation in ALI/ARDS remains unclear. Here, we reported an increase in overall expression levels of m6A and METTL14 in circulating monocyte-derived macrophages recruited to the lung following ALI, which is correlated with the severity of lung injury. We further demonstrated the critical function of METTL14 in activating NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome in vitro and in mouse models of ALI/ARDS, and validated NLRP3 as the downstream target of METTL14 by the m6A RNA immunoprecipitation (MeRIP) and RIP assays. Mechanistically, METTL14-methylated NLRP3 transcripts were subsequently recognized by insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), an m6A reader, which stabilized NLRP3 mRNA. Furthermore, we observed that IGF2BP2 knockdown diminished LPS-induced ALI in mice by downregulating NLRP3 expression. In summation, our study revealed that the molecular mechanism underlying the pathogenesis of ALI/ARDS involves METTL14-mediated activation of NLRP3 inflammasome in an IGF2BP2 dependent manner, thereby demonstrating the potential of METTL14 and IGF2BP2 as promising biomarkers and therapeutic targets for ALI/ARDS treatment.

The role of m6A RNA methylation in autoimmune diseases: Novel therapeutic opportunities

N6-methyladenosine (m6A) modifications, as one of the most common forms of internal RNA chemical modifications in eukaryotic cells, have gained increasing attention in recent years. The m6A RNA modifications exert various crucial roles in various biological processes, such as embryonic development, neurogenesis, circadian rhythms, and tumorigenesis. Recent advances have highlighted that m6A RNA modification plays an important role in immune response, especially in the initiation and progression of autoimmune diseases. In this review, we summarized the regulatory mechanisms of m6A methylation and its biological functions in the immune system and mainly focused on recent progress in research on the potential role of m6A RNA methylation in the pathogenesis of autoimmune diseases, thus providing possible biomarkers and potential targets for the prevention and treatment of autoimmune diseases.

Chokeberry reduces inflammation in human preadipocytes

Chokeberry, Aronia melanocarpa, is an indigenous fruit from North America used as food and to prevent chronic disease by Indigenous Peoples. The objective of this study was to test anti-inflammatory effects of anthocyanin on palmitic acid (PA)-induced IL-6 gene expression, IL-6 DNA methylation, and histone (H3) acetylation. Additionally, we examined effects of anthocyanins Cyanidin-3-O-galactoside (C3Gal) and Cyanidin-3-glucoside (C3G) on IL-6 gene expression. Human primary pre-adipocytes were treated with chokeberry juice extract (CBE), C3Gal or C3G in the presence or absence of PA or lipopolysaccharide (LPS). CBE inhibited LPS- and PA-induced IL-6 mRNA expression (p < 0.0001), while C3G and C3Gal had smaller effects. Human IL-6 promoter DNA methylation was increased (p = 0.0256) in CBE treated cells compared to control. Histone H3 acetylations were not affected by CBE or PA treatment. These data indicate that CBE epigenetically reduced PA-induced inflammation by regulating IL-6 DNA methylation without affecting histone modifications in human preadipocyte cells.

METTL3 and METTL14 regulate IL-6 expression via RNA m6A modification of zinc transporter SLC39A9 and DNA methylation of IL-6 in periodontal ligament cells

The inflammatory response is a key process in periodontitis. The N6-methyladenosine (m6A) modification has been proven to be involved in various physiological and pathological processes. This study aims to investigate the role and downstream mechanism of N6-adenosine-enzyme subunits methyltransferase (METTL) 3 and 14 in the inflammatory response of periodontal ligament cells (PDLCs). The total m6A content and the expression of METTL3 and METTL14 were upregulated in lipopolysaccharide (LPS)-stimulated PDLCs. Knockdown of METTL3 or METTL14 suppressed the LPS-induced interleukin (IL)-6 expression, as shown by quantitative polymerase chain reaction (qPCR) and enzyme linked immunosorbent assay (ELISA). Mechanistically, conjoint analysis of m6A sequencing of METTL3-knockdown and METTL14-knockdown PDLCs revealed that the expression of solute carrier family 39 member 9 (SLC39A9) was mediated in a m6A-dependent manner. The suppression of LPS-induced IL-6 by METTL3 or METTL14 knockdown was partially counteracted by SLC39A9 knockdown, which induced downregulation of intracellular zinc via immunofluorescence staining. Amplicon bisulfite sequencing (AmpBS) demonstrated that METTL3/14 knockdown increased the methylation at one position of the IL-6 promoter, while SLC39A9 knockdown decreased it, which was basically consistent with the intracellular zinc concentration and negatively associated with IL-6 expression. Moreover, METTL3 or METTL14 knockdown attenuated the LPS-induced phosphorylation of p38 and JNK mitogen-activated protein kinase (MAPK), which was partially counteracted by SLC39A9 knockdown. These results revealed the "LPS-METTL3/14-SLC39A9-zinc-IL-6" axis and involvement of p38 and JNK MAPK signaling pathway in the inflammatory responses of PDLCs.

Transcriptome-wide N6-methyladenosine methylation profile of atherosclerosis in mice

BACKGROUND

Atherosclerosis (AS) is a critical pathological event during the progression of cardiovascular diseases. It exhibits fibrofatty lesions on the arterial wall and lacks effective treatment. N6-methyladenosine (m6A) is the most common modification of eukaryotic RNA and plays an important role in regulating the development and progression of cardiovascular diseases. However, the role of m6A modification in AS remains largely unknown. Therefore, in this study, we explored the transcriptome distribution of m6A modification in AS and its potential mechanism.

METHODS

Methylation Quantification Kit was used to detect the global m6A levels in the aorta of AS mice. Western blot was used to analyze the protein level of methyltransferases. Methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were used to obtain the first transcriptome range analysis of the m6A methylene map in the aorta of AS mice, followed by bioinformatics analysis. qRT-PCR and MeRIP-qRT-PCR were used to measure the mRNA and m6A levels in target genes.

RESULTS

The global m6A and protein levels of methyltransferase METTL3 were significantly increased in the aorta of AS mice. However, the protein level of demethylase ALKBH5 was significantly decreased. Through MeRIP-seq, we obtained m6A methylation maps in AS and control mice. In total, 26,918 m6A peaks associated with 13,744 genes were detected in AS group, whereas 26,157 m6A peaks associated with 13,283 genes were detected in the control group. Peaks mainly appeared in the coding sequence (CDS) regions close to the stop codon with the RRACH motif. Moreover, functional enrichment analysis demonstrated that m6A-containing genes were significantly enriched in AS-relevant pathways. Interestingly, a negative correlation between m6A methylation abundance and gene expression level was found through the integrated analysis of MeRIP-seq and RNA-seq data. Among the m6A-modified genes, a hypo-methylated but up-regulated (hypo-up) gene Fabp5 may be a potential biomarker of AS.

CONCLUSIONS

Our study provides transcriptome-wide m6A methylation for the first time to determine the association between m6A modification and AS progression. Our study lays a foundation for further exploring the pathogenesis of AS and provides a new direction for the treatment of AS.

Qinzhu Liangxue inhibits IL-6-induced hyperproliferation and inflammation in HaCaT cells by regulating METTL14/SOCS3/STAT3 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Psoriasis, an immune-mediated chronic inflammatory skin condition, is treatable with Qinzhu Liangxue (QZLX), a therapeutic medicinal plant formula used in clinical practice. However, further investigation is needed to clarify its molecular mechanisms of action.

AIM OF THE STUDY

The potential biological mechanisms of QZLX to alleviate psoriasis involving IL-6-induced hyperproliferation and inflammation by regulating METTL14/SOCS3/STAT3 axis.

MATERIALS AND METHODS

HaCaT cell model was induced by IL-6, and dealt with serum containing QZLX. In addition, shRNAs and siRNAs were used for gene silencing, viruses were collected 48 h post-transfection and infected HaCaT cells. Cell viability was detected by CCK-8 assay, cell cycle was determined by flow cytometry. Finally, psoriasis mice model was induced by IMQ cream, then back skin tissue was used for hematoxylin and eosin (H&E). The content of IL-1β, IL-6, and IL-8 in cell supernatants were analyzed using ELISA kits. Analysis of SOCS3 was used by quantitative RT-PCR, the expression level of SOCS3, METTL3, METTL14, WTAP, SOCS3, YTHDF2, p-STAT3 and STAT3 in HaCaT cells transduced with METTL14 overexpression was detected by Western blot.

RESULTS

All results indicated that QZLX could significantly alleviate IL-6-induced HaCaT cell viability, cell cycle progression, and inhibit the level of IL-1β, IL-6, and IL-8. The m6A levels and level of METTL14 in HaCaT cells treated with IL-6 were enhanced, while it was reversed by QZLX. METTL14 silencing could inhibit IL-6-induced HaCaT cell viability, cell cycle progression and inflammation response, while SOCS3 overexpression also suppressed METTL14-induced HaCaT cell viability, cell cycle progression and inflammation. QZLX could significantly enhance the expression level of SOCS3, while inhibit the level of METTL14, and p-STAT3/STAT3. In addition, QZLX inhibits METTL14-induced HaCaT cell viability, cell cycle progression, and inhibits the level of IL-1β, IL-6, and IL-8.

CONCLUSIONS

Our finding suggested that QZLX ameliorated the inflammation response of psoriasis and performed the potential anti-psoriasis effect by regulating METTL14/SOCS3/STAT3 axis in both mice and HaCaT cells psoriasis model. Therefore, our study demonstrated a significant strategy for inhibiting psoriasis inflammation via targeting METTL14/SOCS3/STAT3 axis.

Recent advances in anti-inflammatory active components and action mechanisms of natural medicines

Inflammation is a series of reactions caused by the body's resistance to external biological stimuli. Inflammation affects the occurrence and development of many diseases. Anti-inflammatory drugs have been used widely to treat inflammatory diseases, but long-term use can cause toxic side-effects and affect human functions. As immunomodulators with long-term conditioning effects and no drug residues, natural products are being investigated increasingly for the treatment of inflammatory diseases. In this review, we focus on the inflammatory process and cellular mechanisms in the development of diseases such as inflammatory bowel disease, atherosclerosis, and coronavirus disease-2019. Also, we focus on three signaling pathways (Nuclear factor-kappa B, p38 mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription-3) to explain the anti-inflammatory effect of natural products. In addition, we also classified common natural products based on secondary metabolites and explained the association between current bidirectional prediction progress of natural product targets and inflammatory diseases.

Novel soybean polypeptide dglycin alleviates atherosclerosis in apolipoprotein E-deficient mice

Atherosclerosis is a dominant cause of cardiovascular disease. Accumulation of low-density lipoproteins (LDL), formation of foam cells, and endothelial dysfunction within the arterial intima contribute to atherosclerotic plaque formation. Soy consumption is thought to have positive effect on the prevention of atherosclerosis. Therefore, in the present study, a novel soybean polypeptide dglycin was purified and characterized. Oral administration of 20 mg/g.d dglycin reduced 47.6 % lesion area, and 49.1 % lipid deposition in the atherosclerotic plaques in aortic roots in ApoE-/- mice. In addition, it decreased the levels of 26.0 % plasma low-density lipoprotein, 27.2 % triglyceride, 40.1 % cholesterol, 25.1 % malondialdehyde and 24.2 % tumor necrosis factor-alpha (TNFα). In vitro experiments revealed that dglycin inhibited inflammatory cytokine secretion from aortic endothelial cells via the inhibition of NF-κB signaling. Furthermore, it inhibited reactive oxygen species generation, subsequently enhanced cell viability, and protected aortic endothelial cells from necrosis and apoptosis via mitochondrial function improvement. On the other hand, dglycin prevented the uptake of oxidized LDL by macrophages via suppressing the expression of scavenger receptor class A1, which suggested that dglycin prevented foam cell formation. Therefore, dglycin alleviated the early-stage of atherosclerosis via depressing inflammation, lipid deposition, protecting aortic endothelial cells and preventing foam cell formation.

N6-Methyladenosine (m6A) Modification in Natural Immune Cell-Mediated Inflammatory Diseases

The post-transcriptional N6-methyladenosine (m6A) modification of RNA influences stability, transport, and translation with implications for various physiological and pathological processes. Immune cell development, differentiation, and activation are also thought to be regulated by m6A and affect host defense against pathogens and inflammatory response with impacts on infectious, neoplastic, autoimmune, cardiovascular, hepatic, and osteal diseases. The current review summarizes recent research on m6A in monocyte/macrophages, neutrophils, dendritic cells, natural killer cells, and microglia and gives insights into epigenetic modifications of the immune system and novel therapeutic strategies for immune-related diseases.

RNA modification in cardiovascular disease: implications for therapeutic interventions

Cardiovascular disease (CVD) is the leading cause of death in the world, with a high incidence and a youth-oriented tendency. RNA modification is ubiquitous and indispensable in cell, maintaining cell homeostasis and function by dynamically regulating gene expression. Accumulating evidence has revealed the role of aberrant gene expression in CVD caused by dysregulated RNA modification. In this review, we focus on nine common RNA modifications: N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N4-acetylcytosine (ac4C), pseudouridine (Ψ), uridylation, adenosine-to-inosine (A-to-I) RNA editing, and modifications of U34 on tRNA wobble. We summarize the key regulators of RNA modification and their effects on gene expression, such as RNA splicing, maturation, transport, stability, and translation. Then, based on the classification of CVD, the mechanisms by which the disease occurs and progresses through RNA modifications are discussed. Potential therapeutic strategies, such as gene therapy, are reviewed based on these mechanisms. Herein, some of the CVD (such as stroke and peripheral vascular disease) are not included due to the limited availability of literature. Finally, the prospective applications and challenges of RNA modification in CVD are discussed for the purpose of facilitating clinical translation. Moreover, we look forward to more studies exploring the mechanisms and roles of RNA modification in CVD in the future, as there are substantial uncultivated areas to be explored.

Comprehensive Transcriptomic Profiling of m6A Modification in Age-Related Hearing Loss

Age-related hearing loss (ARHL), also known as presbycusis, is one of the most common neurodegenerative disorders in elderly individuals and has a prevalence of approximately 70-80% among individuals aged 65 and older. As ARHL is an intricate and multifactorial disease, the exact pathogenesis of ARHL is not fully understood. There is evidence that transcriptional dysregulation mediated by epigenetic modifications is widespread in ARHL. However, the potential role of N6-methyladenosine (m6A) modification, as a crucial component of epigenetics, in ARHL progression remains unclear. In this study, we confirmed that the downregulation of m6A modification in cochlear tissues is related to ARHL and found that the expression of the m6A methylation regulators Wilms tumour suppressor-1-associated protein (WTAP), methyltransferase-like 3 (METTL3), ALKB homologous protein 5 (ALKBH5) and fat mass and obesity-associated protein (FTO) is decreased significantly at the mRNA and protein levels in ARHL mice. Then, we used methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and RNA sequencing (RNA-Seq) to identify the differentially m6A-methylated genes in the cochlear tissues of ARHL mice. A total of 3438 genes with differential m6A methylation were identified, of which 1332 genes were m6A-hypermethylated and 2106 genes were m6A-hypomethylated in the ARHL group compared to the control group according to MeRIP-seq. Further joint analysis of RNA-Seq and MeRIP-Seq data showed that 262 genes had significant differences in both mRNA expression and m6A methylation. GO and KEGG analyses indicated that 262 unique genes were enriched mainly in the PI3K-AKT signalling pathway. In conclusion, the results of this study reveal differential m6A methylation patterns in the cochlear tissues of ARHL mice, providing a theoretical basis for further study of the pathogenesis of ARHL and potential therapeutic strategies.

The Mechanism of Interleukin 33-Induced Stimulation of Interleukin 6 in MLO-Y4 Cells

The differentiation and function of osteocytes are controlled by surrounding cells and mechanical stress; however, the detailed mechanisms are unknown. Recent findings suggest that IL-33 is highly expressed in periodontal tissues in orthodontic tooth movement. The present study aimed to elucidate the effect of IL-33 on the expression of regulatory factors for bone remodeling and their molecular mechanisms in the osteocyte-like cell line MLO-Y4. MLO-Y4 cells were treated with IL-33, and the activation of intracellular signaling molecules and transcriptional factors was determined using Western blot analysis and chromatin immunoprecipitation assay. IL-33 treatment enhanced the expression of IL-6 in MLO-Y4 cells, which was suppressed by the knockdown of the IL-33 receptor ST2L. Additionally, IL-33 treatment induced activation of NF-κB, JNK/AP-1, and p38 MAPK signaling pathways in MLO-Y4 cells. Moreover, pretreatment with specific inhibitors of NF-κB, p38 MAPK, and JNK/AP-1 attenuated the IL-33-induced expression of IL-6. Furthermore, chromatin immunoprecipitation indicated that IL-33 increased c-Jun recruitment to the IL-6 promoter. Overall, these results suggest that IL-33 induces IL-6 expression and regulates osteocyte function via activation of the NF-κB, JNK/AP-1, and p38 MAPK pathways through interaction with ST2L receptors on the plasma membrane.

Dihydroartemisinin ameliorates innate inflammatory response induced by Streptococcussuis-derived muramidase-released protein via inactivation of TLR4-dependent NF-κB signaling

Muramidase-released protein (MRP) is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis (S. suis). However, the identification of viable therapeutics for S. suis infection was hindered by the absence of an explicit mechanism for MRP-actuated inflammation. Dihydroartemisinin (DhA) is an artemisinin derivative with potential anti-inflammatory activity. The modulatory effect of DhA on the inflammatory response mediated by the virulence factor MRP remains obscure. This research aimed to identify the signaling mechanism by which MRP triggers the innate immune response in mouse spleen and cultured macrophages. With the candidate mechanism in mind, we investigated DhA for its ability to dampen the pro-inflammatory response induced by MRP. The innate immune response in mice was drastically triggered by MRP, manifesting as splenic and systemic inflammation with splenomegaly, immune cell infiltration, and an elevation in pro-inflammatory cytokines. A crucial role for Toll-like receptor 4 (TLR4) in coordinating the MRP-mediated inflammatory response via nuclear factor-kappa B (NF-κB) activation was revealed by TLR4 blockade. In addition, NF-κB-dependent transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinases (MAPKs) activation was required for the inflammatory signal transduction engendered by MRP. Intriguingly, we observed an alleviation effect of DhA on the MRP-induced immune response, which referred to the suppression of TLR4-mediated actuation of NF-κB-STAT3/MAPK cascades. The inflammatory response elicited by MRP is relevant to TLR4-dependent NF-κB activation, followed by an increase in the activity of STAT3 or MAPKs. DhA mitigates the inflammation process induced by MRP via blocking the TLR4 cascade, highlighting the therapeutic potential of DhA in targeting S. suis infection diseases.

N6-Methyladenosine in Vascular Aging and Related Diseases: Clinical Perspectives

Aging leads to progressive deterioration of the structure and function of arteries, which eventually contributes to the development of vascular aging-related diseases. N6-methyladenosine (m6A) is the most prevalent modification in eukaryotic RNAs. This reversible m6A RNA modification is dynamically regulated by writers, erasers, and readers, playing a critical role in various physiological and pathological conditions by affecting almost all stages of the RNA life cycle. Recent studies have highlighted the involvement of m6A in vascular aging and related diseases, shedding light on its potential clinical significance. In this paper, we comprehensively discuss the current understanding of m6A in vascular aging and its clinical implications. We discuss the molecular insights into m6A and its association with clinical realities, emphasizing its significance in unraveling the mechanisms underlying vascular aging. Furthermore, we explore the possibility of m6A and its regulators as clinical indicators for early diagnosis and prognosis prediction and investigate the therapeutic potential of m6A-associated anti-aging approaches. We also examine the challenges and future directions in this field and highlight the necessity of integrating m6A knowledge into patient-centered care. Finally, we emphasize the need for multidisciplinary collaboration to advance the field of m6A research and its clinical application.

Exosomes derived from LPS-preconditioned bone marrow-derived MSC modulate macrophage plasticity to promote allograft survival via the NF-κB/NLRP3 signaling pathway

OBJECTIVES

This study investigated whether exosomes from LPS pretreated bone marrow mesenchymal stem cells (LPS pre-MSCs) could prolong skin graft survival.

METHODS

The exosomes were isolated from the supernatant of MSCs pretreated with LPS. LPS pre-Exo and rapamycin were injected via the tail vein into C57BL/6 mice allografted with BALB/c skin; graft survival was observed and evaluated. The accumulation and polarization of macrophages were examined by immunohistochemistry. The differentiation of macrophages in the spleen was analyzed by flow cytometry. For in vitro, an inflammatory model was established. Specifically, bone marrow-derived macrophages (BMDMs) were isolated and cultured with LPS (100 ng/ml) for 3 h, and were further treated with LPS pre-Exo for 24 h or 48 h. The molecular signaling pathway responsible for modulating inflammation was examined by Western blotting. The expressions of downstream inflammatory cytokines were determined by Elisa, and the polarization of macrophages was analyzed by flow cytometry.

RESULTS

LPS pre-Exo could better ablate inflammation compared to untreated MSC-derived exosomes (BM-Exo). These loaded factors inhibited the expressions of inflammatory factors via a negative feedback mechanism. In vivo, LPS pre-Exo significantly attenuated inflammatory infiltration, thus improving the survival of allogeneic skin graft. Flow cytometric analysis of BMDMs showed that LPS pre-Exo were involved in the regulation of macrophage polarization and immune homeostasis during inflammation. Further investigation revealed that the NF-κB/NLRP3/procaspase-1/IL-1β signaling pathway played a key role in LPS pre-Exo-mediated regulation of macrophage polarization. Inhibiting NF-κB in BMDMs could abolish the LPS-induced activation of inflammatory pathways and the polarization of M1 macrophages while increasing the proportion of M2 cells.

CONCLUSION

LPS pre-Exo are able to switch the polarization of macrophages and enhance the resolution of inflammation. This type of exosomes provides an improved immunotherapeutic potential in prolonging graft survival.

Membrane contact sites orchestrate cholesterol homeostasis that is central to vascular aging

Chronological age causes structural and functional vascular deterioration and is a well-established risk factor for the development of cardiovascular diseases, leading to more than 40% of all deaths in the elderly. The etiology of vascular aging is complex; a significant impact arises from impaired cholesterol homeostasis. Cholesterol level is balanced through synthesis, uptake, transport, and esterification, the processes executed by multiple organelles. Moreover, organelles responsible for cholesterol homeostasis are spatially and functionally coordinated instead of isolated by forming the membrane contact sites. Membrane contact, mediated by specific protein-protein interaction, pulls opposing organelles together and creates the hybrid place for cholesterol transfer and further signaling. The membrane contact-dependent cholesterol transfer, together with the vesicular transport, maintains cholesterol homeostasis and has intimate implications in a growing list of diseases, including vascular aging-related diseases. Here, we summarized the latest advances regarding cholesterol homeostasis by highlighting the membrane contact-based regulatory mechanism. We also describe the downstream signaling under cholesterol homeostasis perturbations, prominently in cholesterol-rich conditions, stimulating age-dependent organelle dysfunction and vascular aging. Finally, we discuss potential cholesterol-targeting strategies for therapists regarding vascular aging-related diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology.

METTL14 represses osteoclast formation to ameliorate osteoporosis via enhancing GPX4 mRNA stability

Excessive bone resorption by osteoclasts results in the development of multiple bone disorders including osteoporosis. This study aimed to explore the biological function of methyltransferase-like14 (METTL14) in osteoclast formation, as well as its related mechanisms. Expression levels of METTL14, GPX4 and osteoclast-related proteins TRAP, NFATc1, c-Fos were detected by qRT-PCR and Western blotting. The osteoporosis model was established in mice by bilateral ovariectomy (OVX). Bone histomorphology was determined by micro-CT and H&E staining. NFATc1 expression in bone tissues was determined by immunohistochemical staining. Proliferation of primary bone marrow macrophages cells (BMMs) was assessed by MTT assay. Osteoclast formation was observed by TRAP staining. The regulatory mechanism was evaluated by RNA methylation quantification assay, MeRIP-qPCR, dual luciferase reporter assay, and RIP, respectively. METTL14 was down-regulated in the serum samples of postmenopausal osteoporotic women, which was positively associated with bone mineral density (BMD). Osteoclast formation was promoted in OVX-treated METTL14+/- mice as compared with wild-type littermates. Conversely, METTL14 overexpression repressed RANKL-induced osteoclast differentiation of BMMs. Mechanistically, METTL14-mediated m6A modification post-transcriptionally stabilized glutathione peroxidase 4 (GPX4), with the assistance of Hu-Antigen R (HuR). Finally, GPX4 depletion-mediated osteoclast formation in BMMs could be counteracted by METTL14 or HuR overexpression. Collectively, METTL14 inhibits osteoclastogenesis and bone resorption via enhancing GPX4 stability through an m6A-HuR dependent mechanism. Therefore, targeting METTL14 might be a novel promising treatment strategy for osteoporosis.

METTL14 regulates microglia/macrophage polarization and NLRP3 inflammasome activation after ischemic stroke by the KAT3B-STING axis

N6-methyladenosine (m6A) plays a crucial role in ischemic stroke, whereas the role of methyltransferase-like 14 (METTL14) in ischemic stroke remains unknown. A model of middle cerebral artery occlusion (MCAO) in rats and oxygen-glucose deprivation/reperfusion (OGD/R) model in HAPI cells were used to simulate ischemic stroke in vivo and in vitro. We found that METTL14 level was upregulated in microglia/macrophage after MCAO and OGD/R. METTL14 enhanced the expression of KAT3B by promoting the m6A modification of KAT3B mRNA. STING has been identified as a target for KAT3B and KAT3B increased STING expression by enhancing H3K27ac in the STING promoter. METTL14 promoted M1 polarization and NLRP3 inflammasome/pyroptosis axis by the KAT3B-STING signaling after OGD/R. METTL14 depletion relieved brain injury by inhibiting M1-like microglia/macrophage polarization and NLRP3 inflammasome/pyroptosis axis in MCAO rats. These findings indicate that METTL14 depletion relieves MCAO-induced brain injury, probably via switching microglia/macrophage from M1 towards M2 and restraining NLRP3 inflammasome/pyroptosis axis in microglia/macrophage.

RNA methylations in depression, from pathological mechanism to therapeutic potential

Depression is caused by a variety of factors such as genetic factors, biological factors, and psychosocial factors, and the pathogenesis is complex. RNA methylations and related downstream signaling pathways influence a variety of biological mechanisms, including cell differentiation, tumorigenesis, sex determination, and stress response. In this work, we searched the PubMed, Web of Science, National Library of Science and Technology (NSTL), and ScienceDirect Online (SDOL) databases to summarize the biological roles of RNA methylations and their impact on the pathological mechanisms of depression. RNA methylations play a key role in the development of many diseases, and current research shows that RNA methylations are also closely linked to depression. RNA methylations in depression mainly involve "writers" (mediating the methylation modification process of RNAs), "erasers" (mediating the demethylation modification process of RNA methylation). Fat Mass and Obesity Associated (FTO) influences the development of depression by increasing body mass index (BMI), decreases the dopamine level, inhibits the adrenoceptor beta 2 (ADRB2)-c-Myc-sirt1 pathway, results in the m6A/m6Am dysregulation in brain, and may be involved in the pathogenesis of depression. The study of RNA methylations in depression has further deepened our understanding of the pathogenesis and development process of depression, provides new perspectives for the study of the pathological mechanism of depression, and provides new targets for the prevention and treatment of this disease.

LPS adsorption and inflammation alleviation by polymyxin B-modified liposomes for atherosclerosis treatment

Chronic inflammation is critical in the onset and progression of atherosclerosis (AS). The lipopolysaccharide (LPS) level in the circulation system is elevated in AS patients and animal models, which is correlated with the severity of AS. Inspired by the underlying mechanism that LPS could drive the polarization of macrophages toward the M1 phenotype, aggravate inflammation, and ultimately contribute to the exacerbation of AS, LPS in the circulation system was supposed to be the therapeutic target for AS treatment. In the present study, polymyxin (PMB) covalently conjugated to PEGylated liposomes (PLPs) were formulated to adsorb LPS through specific interactions between PMB and LPS. In vitro, the experiments demonstrated that PLPs could adsorb LPS, reduce the polarization of macrophages to M1 phenotype and inhibit the formation of foam cells. In vivo, the study revealed that PLPs treatment reduced the serum levels of LPS and pro-inflammatory cytokines, decreased the proportion of M1-type macrophages in AS plaque, stabilized AS plaque, and downsized the plaque burdens in arteries, which eventually attenuated the progression of AS. Our study highlighted LPS in the circulation system as the therapeutic target for AS and provided an alternative strategy for AS treatment.

MALT1 accelerates proatherogenic vascular smooth muscle cell growth, invasion and synthetic phenotype switching via nuclear factor‑κB signaling‑dependent way

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates T helper cell differentiation and nuclear factor-κB (NF-κB) pathway-mediated inflammation and potentially regulates lipid metabolism, which are all critical factors involved in atherosclerosis. The present study aimed to investigate the effect of MALT1 on the cellular functions of proatherogenic vascular smooth muscle cells (VSMCs). Therefore, to establish a human proatherogenic VSMC model, VSMCs were treated with different doses of oxidized low-density lipoprotein (oxLDL). Subsequently, the effect of MALT1 overexpression or knockdown in proatherogenic VSMCs treated with or without NF-κB activator was also explored. The results showed that treatment of proatherogenic VSMCs with oxLDL significantly elevated the mRNA and protein expression levels of MALT1 in a dose-dependent manner. Furthermore, MALT1 overexpression enhanced cell viability, invasion and phenotype switching and reduced apoptosis in proatherogenic VSMCs. However, MALT1 knockdown exerted the opposite effect on the above cellular functions. Additionally, the results revealed that MALT1 could positively regulate the NF-κB pathway in proatherogenic VSMCs. Moreover, treatment of proatherogenic VSMCs with NF-κB activator not only exacerbated the dysregulation of cellular functions, but also hampered the effect of MALT1 knockdown on attenuating cell growth, invasion and synthetic phenotype switching, thus suggesting that NF-κB was essential for the regulation of MALT1-triggered functions in proatherogenic VSMCs. In conclusion, the current study suggested that MALT1 could exacerbate cell viability, mobility and synthetic phenotype switching of proatherogenic VSMCs in a NF-κB signaling-dependent manner. Therefore, MALT1 could be considered as a potential therapeutic target for atherosclerosis.

Levels and clinical significance of the m6A methyltransferase METTL14 in patients with coronary heart disease

Objective

To investigate the association of methyltransferase-like protein 14 (METTL14) expression with coronary heart disease (CHD).

Methods

Three hundred and sixteen patients who attended Henan Provincial People's Hospital between June 2019 and February 2021 with principal symptoms of pain or tightness in the chest and who underwent coronary angiography for definitive diagnosis were enrolled. The uric acid, TG, TC, LDL-C, HDL-C, apolipoprotein A1, free fatty acid, lipoprotein a, homocysteine, CRP, and SAA levels were examined. The levels of METTL14, TNF-α, MCP-1, VCAM-1, ICAM-1, and IL-6 were evaluated by ELISA.

Results

Patients with CHD had significantly higher m6A methyltransferase activity. In addition, the incidence of diabetes and hypertension, as well as the concentrations of TC, CRP, and SAA were higher in CHD patients. Patients with coronary lesion branches also had significantly increased TG, LDL-C, CRP, and SAA levels. TNF-α, MCP-1, VCAM-1, ICAM-1, and IL-6 expression was also markedly increased in the CHD group (P < 0.001) as was the expression of METTL14 (P < 0.001). The METTL14 expression levels also differed significantly in relation to the number of branches with lesions (P < 0.01) and were correlated with SAA, VCAM-1, ICAM-1, IL-6, and the Gensini score. ROC curve analyses of METTL14 in CHD indicated an AUC of 0.881 (0.679, 0.894) with a cut-off value of 342.37, a sensitivity of 77%, and a specificity of 84%. MCP-1, VCAM-1, IL-6, SAA, and METTL14 were found to independently predict CHD risk.

Conclusions

METTL14 levels were found to be positively associated with inflammatory markers and to be an independent predictor of CHD risk.

Microenvironment modulation by key regulators of RNA N6-methyladenosine modification in respiratory allergic diseases

BACKGROUND

RNA N6-methyladenosine (m6A) regulators are considered post-transcriptional regulators that affect several biological functions, and their role in immunity, in particular, is emerging. However, the role of m6A regulators in respiratory allergic diseases remains unclear. Therefore, we aimed to investigate the role of key m6A regulators in mediating respiratory allergic diseases and immune microenvironment infiltration characteristics.

METHODS

We downloaded gene expression profiles of respiratory allergies from the Gene Expression Omnibus (GEO) database and we performed hierarchical clustering, difference analysis, and construction of predictive models to identify hub m6A regulators that affect respiratory allergies. Next, we investigate the underlying biological mechanisms of key m6A regulators by performing PPI network analysis, functional enrichment analysis, and immune microenvironment infiltration analysis. In addition, we performed a drug sensitivity analysis on the key m6A regulator, hoping to be able to provide some implications for clinical medication.

RESULTS

In this study, we identified four hub m6A regulators that affect the respiratory allergy and investigated the underlying biological mechanisms. In addition, studies on the characteristics of immune microenvironment infiltration revealed that the expression of METTL14, METTL16, and RBM15B correlated with the infiltration of the mast and Th2 cells in respiratory allergy, and METTL16 expression was found to be significantly negatively correlated with macrophages for the first time (R = -0.53, P < 0.01). Finally, a key m6A regulator, METTL14, was screened by combining multiple algorithms. In addition, by performing a drug sensitivity analysis on METTL14, we hypothesized that it may play an important role in the improvement of allergic symptoms in the upper and lower airways with topical nasal glucocorticoids.

CONCLUSIONS

Our findings suggest that m6A regulators, particularly METTL14, play a crucial role in the development of respiratory allergic diseases and the infiltration of immune cells. These results may provide insight into the mechanism of action of methylprednisolone in treating respiratory allergic diseases.

M6A modification promotes blood-brain barrier breakdown during cerebral ischemia/reperfusion injury through increasing matrix metalloproteinase 3 expression

Blood-brain barrier (BBB) breakdown is a critical event in cerebral ischemia-reperfusion (I/R) injury, and matrix metalloproteinases (MMPs), which are proteolytic enzymes, play essential roles in BBB breakdown through degrading the extracellular matrix. N6-Methyladenosine (m6A), the most common and reversible mRNA modification, has an important role in the progression of cerebral I/R injury. However, whether m6A is related to BBB breakdown and MMPs expression in cerebral I/R injury is still not clear. In this study, we explored the potential effects of m6A modification on BBB breakdown in cerebral I/R injury and its underlying mechanisms using mice subjected to transient middle cerebral artery occlusion and reperfusion (MCAO/R), and mouse brain endothelial cells treated with oxygen-glucose deprivation and reoxygenation (OGD/R). We find that MMP3 expression is highly expressed and positively associated with the m6A writer CBLL1 (Cbl proto-oncogene like 1) in cerebral I/R injury in vivo and in vitro. Furthermore, MMP3 mRNA occurs m6A modification in mouse brain endothelial cells, and the m6A modification level of MMP3 mRNA is significantly increased in cerebral I/R injury. Moreover, inhibition of m6A modification reduces MMP3 expression and ameliorates BBB breakdown in cerebral I/R in vivo and in vitro. In conclusion, m6A modification promotes BBB breakdown in cerebral I/R injury through increasing MMP3 expression, indicating that m6A may be a potential therapeutic target for cerebral I/R injury.

Critical roles of m6A methylation in cardiovascular diseases

Cardiovascular diseases (CVDs) have been established as a major cause of mortality globally. However, the exact pathogenesis remains obscure. N6-methyladenosine (m⁶A) methylation is the most common epigenetic modification on mRNAs regulated by methyltransferase complexes (writers), demethylase transferases (erasers) and binding proteins (readers). It is now understood that m⁶A is a major player in physiological and pathological cardiac processes. m⁶A methylation are potentially involved in many mechanisms, for instance, regulation of calcium homeostasis, endothelial function, different forms of cell death, autophagy, endoplasmic reticulum stress, macrophage response and inflammation. In this review, we will summarize the molecular functions of m⁶A enzymes. We mainly focus on m⁶A-associated mechanisms and functions in CVDs, especially in heart failure and ischemia heart disease. We will also discuss the potential application and clinical transformation of m⁶A modification.

A plasma proteomic approach in patients with heart failure after acute myocardial infarction: insights into the pathogenesis and progression of the disease

Aims

The pathogenesis of disease progression targets for patients with heart failure after acute myocardial infarction was investigated by using plasma proteomics.

Methods

The plasma proteomes of acute myocardial infarction patients with (MI-HF) and without (MI-WHF) heart failure were compared. Each group consisted of 10 patients who were matched for age and sex. The peptides were analyzed by 2-dimensional liquid chromatography coupled to tandem mass spectrometry in a high definition mode. Parallel reaction monitoring (PRM) verified the selected target proteins.

Results

We identified and quantified 2,589 and 2,222 proteins, respectively, and found 117 differentially expressed proteins (DEPs) (≥1.5-fold), when the MI-HF and MI-WHF groups were compared. Of these 51 and 66 were significantly up-regulated and down-regulated, respectively. The significant DEPs was subjected to protein-protein interaction network analysis which revealed a central role of the NF-κB signaling pathway in the MI-HF patients. PRM verified that MB, DIAPH1, VNN1, GOT2, SLC4A1, CRP, CKM, SOD3, F7, DLD, PGAM2, GOT1, UBA7 and HYOU1 were 14 proteins which were highly expressed in MI-HF patients.

Conclusions

These findings showed a group of proteins related to the NF-κB signaling pathway in the pathogenesis of patients with poor outcomes after experiencing MI-HF. These proteins may be useful candidate markers for the diagnosis of MI-HF as well as help to elucidate the pathophysiology of this major cause of mortality in older patients.

m6A methylation: a process reshaping the tumour immune microenvironment and regulating immune evasion

N6-methyladenosine (m⁶A) methylation is the most universal internal modification in eukaryotic mRNA. With elaborate functions executed by m⁶A writers, erasers, and readers, m⁶A modulation is involved in myriad physiological and pathological processes. Extensive studies have demonstrated m⁶A modulation in diverse tumours, with effects on tumorigenesis, metastasis, and resistance. Recent evidence has revealed an emerging role of m⁶A modulation in tumour immunoregulation, and divergent m⁶A methylation patterns have been revealed in the tumour microenvironment. To depict the regulatory role of m⁶A methylation in the tumour immune microenvironment (TIME) and its effect on immune evasion, this review focuses on the TIME, which is characterized by hypoxia, metabolic reprogramming, acidity, and immunosuppression, and outlines the m⁶A-regulated TIME and immune evasion under divergent stimuli. Furthermore, m⁶A modulation patterns in anti-tumour immune cells are summarized.

N6-Methyladenosine and Reader Protein YTHDF2 Enhance the Innate Immune Response by Mediating DUSP1 mRNA Degradation and Activating Mitogen-Activated Protein Kinases during Bacterial and Viral Infections

Mitogen-activated protein kinases (MAPKs) play critical roles in the induction of numerous cytokines, chemokines, and inflammatory mediators that mobilize the immune system to counter pathogenic infections. Dual-specificity phosphatase 1 (DUSP1) is a member of the dual-specificity phosphatases that inactivates MAPKs through a negative-feedback mechanism. Here, we report that in response to viral and bacterial infections, not only the DUSP1 transcript but also its N6-methyladenosine (m6A) levels rapidly increase together with that of the m6A reader protein YTHDF2, resulting in enhanced YTHDF2-mediated DUSP1 transcript degradation. The knockdown of DUSP1 promotes p38 and Jun N-terminal kinase (JNK) phosphorylation and activation, thus increasing the expression of innate immune response genes, including the interleukin-1β (IL-1β), colony-stimulating factor 3 (CSF3), transglutaminase 2 (TGM2), and proto-oncogene tyrosine-protein kinase Src (SRC) genes. Similarly, the knockdown of the m6A eraser ALKBH5 increases the DUSP1 transcript m6A level, resulting in accelerated transcript degradation, the activation of p38 and JNK, and the enhanced expression of IL-1β, CSF3, TGM2, and SRC. These results demonstrate that m6A and the reader protein YTHDF2 orchestrate optimal innate immune responses during viral and bacterial infections by downregulating the expression of a negative regulator, DUSP1, of the p38 and JNK pathways that are central to innate immune responses against pathogenic infections. IMPORTANCE Innate immunity is central to controlling pathogenic infections and maintaining the homeostasis of the host. In this study, we have revealed a novel mechanism regulating innate immune responses during viral and bacterial infections. We have found that N6-methyladenosine (m6A) and the reader protein YTHDF2 regulate dual-specificity phosphatase 1, a negative regulator of the mitogen-activated protein kinases p38 and JNK, to maximize innate immune responses during viral and bacterial infections. These results provide novel insights into the mechanism regulating innate immunity, which could help in the development of novel approaches for controlling pathogenic infections.

Exosomal miRNAs-mediated macrophage polarization and its potential clinical application

Macrophages are highly heterogeneous and plastic immune cells that play an important role in the fight against pathogenic microorganisms and tumor cells. After different stimuli, macrophages can polarize to the M1 phenotype to show a pro-inflammatory effect and the M2 phenotype to show an anti-inflammatory effect. The balance of macrophage polarization is highly correlated with disease progression, and therapeutic approaches to reprogram macrophages by targeting macrophage polarization are feasible. There are a large number of exosomes in tissue cells, which can transmit information between cells. In particular, microRNAs (miRNAs) in the exosomes can regulate the polarization of macrophages and further affect the progression of various diseases. At the same time, exosomes are also effective "drug" carriers, laying the foundation for the clinical application of exosomes. This review describes some pathways involved in M1/M2 macrophage polarization and the effects of miRNA carried by exosomes from different sources on the polarization of macrophages. Finally, the application prospects and challenges of exosomes/exosomal miRNAs in clinical treatment are also discussed.

The Epigenetic Regulation of RNA N6-Methyladenosine Methylation in Glycolipid Metabolism

The highly conserved and dynamically reversible N6-methyladenine (m6A) modification has emerged as a critical gene expression regulator by affecting RNA splicing, translation efficiency, and stability at the post-transcriptional level, which has been established to be involved in various physiological and pathological processes, including glycolipid metabolism and the development of glycolipid metabolic disease (GLMD). Hence, accumulating studies have focused on the effects and regulatory mechanisms of m6A modification on glucose metabolism, lipid metabolism, and GLMD. This review summarizes the underlying mechanism of how m6A modification regulates glucose and lipid metabolism-related enzymes, transcription factors, and signaling pathways and the advances of m6A regulatory mechanisms in GLMD in order to deepen the understanding of the association of m6A modification with glycolipid metabolism and GLMD.