The METTL3/MALAT1/PTBP1/USP8/TAK1 axis promotes pyroptosis and M1 polarization of macrophages and contributes to liver fibrosis

The role of RNA modifications in disease-associated macrophages

In recent years, the field of epitranscriptomics has witnessed significant breakthroughs with the identification of more than 150 different chemical modifications in different RNA species. It has become increasingly clear that these chemical modifications play an important role in the regulation of fundamental processes linked to cell fate and development. Further interest was sparked by the ability of the epitranscriptome to regulate pathogenesis. However, despite the involvement of macrophages in a multitude of diseases, a clear knowledge gap exists in the understanding of how RNA modifications regulate the phenotype of these cells. Here, we provide a comprehensive overview of the known roles of macrophage RNA modifications in the context of different diseases.

Chemotherapy-mediated lncRNA-induced immune cell plasticity in cancer immunopathogenesis

Tumor cells engage with the immune system in a complex manner, utilizing evasion and adaptability mechanisms. The development of cancer and resistance to treatment relies on the ability of immune cells to adjust their phenotype and function in response to cues from the tumor microenvironment, known as immunological cell plasticity. This study delves into the role of long non-coding RNAs (lncRNAs) in enhancing immune cell flexibility in cancer, focusing on their regulatory actions in the tumor microenvironment and potential therapeutic implications. Through a comprehensive review of existing literature, the study analyzes the impact of lncRNAs on macrophages, T-cells, and MDSCs, as well as the influence of cytokines and growth factors like TNF, IL-6, HGF, and TGFβ on immunological cell plasticity and tumor immunoediting. LncRNAs exert a strong influence on immune cell plasticity through mechanisms such as transcriptional regulation, post-transcriptional modifications, and chromatin remodeling. These RNA molecules intricately modulate gene expression networks, acting as scaffolding, decoys, guides, and sponges. Moreover, both direct cell-cell interactions and soluble chemicals in the tumor microenvironment contribute to enhancing immune cell activation and survival. Understanding the influence of lncRNAs on immune cell flexibility sheds light on the biological pathways of immune evasion and cancer progression. Targeting long non-coding RNAs holds promise for amplifying anti-tumor immunity and overcoming drug resistance in cancer treatment. However, further research is necessary to determine the therapeutic potential of manipulating lncRNAs in the tumor microenvironment.

RNA modifications in the progression of liver diseases: from fatty liver to cancer

Non-alcoholic fatty liver disease (NAFLD) has emerged as a prominent global health concern associated with high risk of metabolic syndrome, and has impacted a substantial segment of the population. The disease spectrum ranges from simple fatty liver to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma (HCC) and is increasingly becoming a prevalent indication for liver transplantation. The existing therapeutic options for NAFLD, NASH, and HCC are limited, underscoring the urgent need for innovative treatment strategies. Insights into gene expression, particularly RNA modifications such as N6 methyladenosine (m6A), hold promising avenues for interventions. These modifications play integral roles in RNA metabolism and cellular functions, encompassing the entire NAFLD-NASH-HCC progression. This review will encompass recent insights on diverse RNA modifications, including m6A, pseudouridine (ψ), N1-methyladenosine (m1A), and 5-methylcytidine (m5C) across various RNA species. It will uncover their significance in crucial aspects such as steatosis, inflammation, fibrosis, and tumorigenesis. Furthermore, prospective research directions and therapeutic implications will be explored, advancing our comprehensive understanding of the intricate interconnected nature of these pathological conditions.

Pyroptosis in health and disease: mechanisms, regulation and clinical perspective

Pyroptosis is a type of programmed cell death characterized by cell swelling and osmotic lysis, resulting in cytomembrane rupture and release of immunostimulatory components, which play a role in several pathological processes. Significant cellular responses to various stimuli involve the formation of inflammasomes, maturation of inflammatory caspases, and caspase-mediated cleavage of gasdermin. The function of pyroptosis in disease is complex but not a simple angelic or demonic role. While inflammatory diseases such as sepsis are associated with uncontrollable pyroptosis, the potent immune response induced by pyroptosis can be exploited as a therapeutic target for anti-tumor therapy. Thus, a comprehensive review of the role of pyroptosis in disease is crucial for further research and clinical translation from bench to bedside. In this review, we summarize the recent advancements in understanding the role of pyroptosis in disease, covering the related development history, molecular mechanisms including canonical, non-canonical, caspase 3/8, and granzyme-mediated pathways, and its regulatory function in health and multiple diseases. Moreover, this review also provides updates on promising therapeutic strategies by applying novel small molecule inhibitors and traditional medicines to regulate pyroptosis. The present dilemmas and future directions in the landscape of pyroptosis are also discussed from a clinical perspective, providing clues for scientists to develop novel drugs targeting pyroptosis.

DNA 5mC and RNA m6A Collaborate to Upregulate Phosphoenolpyruvate Carboxykinase 2 for Kupffer Cell Activation

Both DNA 5-methylcytosine (5mC) and RNA N6-methyladenosine (m6A) modifications are reported to participate in cellular stress responses including inflammation. Phosphoenolpyruvate carboxykinase 2 (PCK2) is upregulated in Kupffer cells (KCs) to facilitate the proinflammatory phosphorylation signaling cascades upon LPS stimulation, yet the role of 5mC and m6A in PCK2 upregulation remain elusive. Here, we report that the significantly augmented PCK2 mRNA and protein levels are associated with global 5mC demethylation coupled with m6A hypermethylation in LPS-activated KCs. The suppression of 5mC demethylation or m6A hypermethylation significantly alleviates the upregulation of PCK2 and proinflammatory cytokines in LPS-challenged KCs. Further reciprocal tests indicate 5mC demethylation is upstream of m6A hypermethylation. Specifically, CpG islands in the promoters of PCK2 and RNA methyltransferase (METTL3 and METTL14) genes are demethylated, while the 3'UTR of PCK2 mRNA is m6A hypermethylated, in LPS-stimulated KCs. These modifications contribute to the transactivation of the PCK2 gene as well as increased PCK2 mRNA stability and protein production via a m6A-mediated mechanism with IGF2BP1 as the reader protein. These results indicate that DNA 5mC and RNA m6A collaborate to upregulate PCK2 expression, respectively, at the transcriptional and post-transcriptional levels during KC activation.

N6-methyladenosine (m6A) RNA modification in fibrosis and collagen-related diseases

Fibrosis is an abnormal tissue healing process characterized by the excessive accumulation of ECM components, such as COL I and COL III, in response to tissue injury or chronic inflammation. Recent advances in epitranscriptomics have underscored the importance of m6A modification in fibrosis. m6A, the most prevalent modification in eukaryotic RNA, is catalyzed by methyltransferases (e.g., METTL3), removed by demethylases (e.g., FTO), and recognized by reader proteins (e.g., YTHDF1/2). These modifications are crucial in regulating collagen metabolism and associated diseases. Understanding the role of m6A modification in fibrosis and other collagen-related conditions holds promise for developing targeted therapies. This review highlights the latest progress in this area.

hucMSC-Ex alleviates inflammatory bowel disease in mice by enhancing M2-type macrophage polarization via the METTL3-Slc37a2-YTHDF1 axis

Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Ex) have emerged as a new treatment strategy for inflammatory bowel disease (IBD) due to their immunoregulatory function. N6-methyladenosine (m6A) plays a crucial role in regulating intestinal immunity, especially in IBD where macrophages play an important role, although its mechanism is not yet fully understood. From this perspective, this research aimed to evaluate the effect of hucMSC-Ex on m6A modification of macrophages in IBD. In the process of alleviating inflammation, hucMSC-Ex promotes macrophage polarization toward the M2 type and regulates intracellular m6A levels by upregulating the expression of m6A "Writer" METTL3 and "Reader" YTHDF1. Solute Carrier Family 37 Member 2 (Slc37a2) was identified by Methylation RNA immunoprecipitation sequencing as the target molecule of the hucMSC-Ex. Mechanically, hucMSC-Ex promoted the binding of METTL3 to the Slc37a2 mRNA complex, and enhanced the binding of Slc37a2 to YTHDF1 to upregulate the intracellular expression of Slc37a2, thereby attenuating the pro-inflammatory function of macrophage. This study confirms the modulatory role of hucMSC-Ex on the m6A modification of macrophages in IBD, providing a new scientific basis for the treatment of IBD with hucMSC-Ex.

METTL3 silencing inhibits ferroptosis to suppress ovarian fibrosis in PCOS by upregulating m6A modification of GPX4

Methyltransferase-like 3 (METTL3) is extensively reported to be involved in organ fibrosis. Ovarian fibrosis is a main characteristic of polycystic ovary syndrome (PCOS). However, the reaction mechanism of METTL3 in PCOS is poorly investigated. This paper was intended to reveal the role and the mechanism of METTL3 in PCOS. Animal and cell models of PCOS were induced by dehydroepiandrosterone (DHEA). H&E staining was performed to detect the pathological alterations in ovary tissues. Masson staining, immunofluorescence, along with western blot measured fibrosis both in vitro and in vivo. To evaluate estrous cycle, vaginal smear was performed. Lipid peroxidation and ferroptosis were evaluated by MDA assay kits, GSH assay kits, immunohistochemistry, Prussian blue staining and western blot. qRT-PCR and western blot were adopted to estimate METTL3 and GPX4 expression. The m6A and hormone secretion levels were respectively assessed by m6A RNA Methylation Quantitative Kit and corresponding kits. The interaction between METTL3 and GPX4 was testified by immunoprecipitation. The fibrosis and ferroptosis were aggravated and m6A and METTL3 expression were increased in ovarian tissues of DHEA-induced PCOS mice. METTL3 silencing alleviated pathological changes, affected hormone secretion level, and repressed fibrosis, lipid peroxidation and ferroptosis in the ovarian tissues of PCOS mice. In vitro, DHEA stimulation increased m6A and METTL3 expression and induced ferroptosis and fibrosis. METTL3 knockdown promoted GPX4 expression in DHEA-induced granulosa cells by m6A modification and restrained DHEA-induced fibrosis, lipid peroxidation and ferroptosis in granulosa cells via elevating GPX4. METTL3 silence inhibited ovarian fibrosis in PCOS, which was mediated through suppressing ferroptosis by upregulating GPX4 in m6A-dependent manner.

Insights into RNA N6-methyladenosine and programmed cell death in atherosclerosis

N6-methyladenosine (m6A) modification stands out among various RNA modifications as the predominant form within eukaryotic cells, influencing numerous cellular processes implicated in disease development. m6A modification has gained increasing attention in the development of atherosclerosis and has become a research hotspot in recent years. Programmed cell death (PCD), encompassing apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis, plays a pivotal role in atherosclerosis pathogenesis. In this review, we delve into the intricate interplay between m6A modification and diverse PCD pathways, shedding light on their complex association during the onset and progression of atherosclerosis. Clarifying the relationship between m6A and PCD in atherosclerosis is of great significance to provide novel strategies for cardiovascular disease treatment.

M6A modification in cardiovascular disease: With a focus on programmed cell death

N6-methyladenosine (m6A) methylation is one of the most predominant internal RNA modifications in eukaryotes and has become a hot spot in the field of epigenetics in recent years. Cardiovascular diseases (CVDs) are a leading cause of death globally. Emerging evidence demonstrates that RNA modifications, such as the m6A modification, are associated with the development and progression of many diseases, including CVDs. An increasing body of studies has indicated that programmed cell death (PCD) plays a vital role in CVDs. However, the molecular mechanisms underlying m6A modification and PCD in CVDs remain poorly understood. Herein, elaborating on the highly complex connections between the m6A mechanisms and different PCD signaling pathways and clarifying the exact molecular mechanism of m6A modification mediating PCD have significant meaning in developing new strategies for the prevention and therapy of CVDs. There is great potential for clinical application.

Suppression of the JAK/STAT pathway inhibits neuroinflammation in the line 61-PFF mouse model of Parkinson's disease

Parkinson's disease (PD) is characterized by neuroinflammation, progressive loss of dopaminergic neurons, and accumulation of α-synuclein (α-Syn) into insoluble aggregates called Lewy pathology. The Line 61 α-Syn mouse is an established preclinical model of PD; Thy-1 is used to promote human α-Syn expression, and features of sporadic PD develop at 9-18 months of age. To accelerate the PD phenotypes, we injected sonicated human α-Syn preformed fibrils (PFFs) into the striatum, which produced phospho-Syn (p-α-Syn) inclusions in the substantia nigra pars compacta and significantly increased MHC Class II-positive immune cells. Additionally, there was enhanced infiltration and activation of innate and adaptive immune cells in the midbrain. We then used this new model, Line 61-PFF, to investigate the effect of inhibiting the JAK/STAT signaling pathway, which is critical for regulation of innate and adaptive immune responses. After administration of the JAK1/2 inhibitor AZD1480, immunofluorescence staining showed a significant decrease in p-α-Syn inclusions and MHC Class II expression. Flow cytometry showed reduced infiltration of CD4+ T-cells, CD8+ T-cells, CD19+ B-cells, dendritic cells, macrophages, and endogenous microglia into the midbrain. Importantly, single-cell RNA-Sequencing analysis of CD45+ cells from the midbrain identified 9 microglia clusters, 5 monocyte/macrophage (MM) clusters, and 5 T-cell (T) clusters, in which potentially pathogenic MM4 and T3 clusters were associated with neuroinflammatory responses in Line 61-PFF mice. AZD1480 treatment reduced cell numbers and cluster-specific expression of the antigen-presentation genes H2-Eb1, H2-Aa, H2-Ab1, and Cd74 in the MM4 cluster and proinflammatory genes such as Tnf, Il1b, C1qa, and C1qc in the T3 cluster. Together, these results indicate that inhibiting the JAK/STAT pathway suppresses the activation and infiltration of innate and adaptive cells, reducing neuroinflammation in the Line 61-PFF mouse model.

The Role of m6A Methylation in Tumor Immunity and Immune-Associated Disorder

N6-methyladenosine (m6A) represents the most prevalent and significant internal modification in mRNA, with its critical role in gene expression regulation and cell fate determination increasingly recognized in recent research. The immune system, essential for defense against infections and maintaining internal stability through interactions with other bodily systems, is significantly influenced by m6A modification. This modification acts as a key post-transcriptional regulator of immune responses, though its effects on different immune cells vary across diseases. This review delineates the impact of m6A modification across major system-related cancers-including those of the respiratory, digestive, endocrine, nervous, urinary reproductive, musculoskeletal system malignancies, as well as acute myeloid leukemia and autoimmune diseases. We explore the pathogenic roles of m6A RNA modifications within the tumor immune microenvironment and the broader immune system, highlighting how RNA modification regulators interact with immune pathways during disease progression. Furthermore, we discuss how the expression patterns of these regulators can influence disease susceptibility to immunotherapy, facilitating the development of diagnostic and prognostic models and pioneering new therapeutic approaches. Overall, this review emphasizes the challenges and prospective directions of m6A-related immune regulation in various systemic diseases throughout the body.

Long non-coding RNA NEAT1 exacerbates NLRP3-mediated pyroptosis in allergic rhinitis through regulating the PTBP1/FOXP1 cascade

BACKGROUND

Allergic Rhinitis (AR) is a prevalent chronic non-infectious inflammation affecting the nasal mucosa. NLRP3-mediated pyroptosis of epithelial cells plays a pivotal role in AR pathogenesis. Herein, we evaluated the impact of the long non-coding RNA nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) on NLR family pyrin domain containing 3 (NLRP3)-mediated pyroptosis in AR.

METHODS

Nasal inflammation levels in ovalbumin (OVA)-induced AR mice were assessed using HE staining, and NLRP3 expression was evaluated through immunohistochemistry. ELISA was utilized to detect OVA-specific IgE, IL-6, IL-5, and inflammatory cytokines (IL-1β, IL-18). Human nasal epithelial cells (HNEpCs) stimulated with IL4/IL13 were used to analyze the mRNA and protein levels of associated genes utilizing RT-qPCR and western blot, respectively. Cell viability and pyroptosis were assessed by CCK-8 and flow cytometry. The targeting relationship between NEAT1, PTBP1 and FOXP1 were analyzed by RIP and RNA pull down assays. FISH and IF analysis were performed to assess the co-localization of NEAT1 and PTBP1.

RESULTS

In both the AR mouse and cellular models, increased levels of NEAT1, PTBP1 and FOXP1 were observed. AR mice exhibited elevated inflammatory infiltration and pyroptosis, evidenced by enhanced expressions of OVA-specific IgE, IL-6, and IL-5, NLRP3, Cleaved-caspase 1, GSDMD-N, IL-1β and IL-18. Functional assays revealed that knockdown of PTBP1 or NEAT1 inhibited pyroptosis while promoting the proliferation of IL4/IL13-treated HNEpCs. Mechanistically, NEAT1 directly interacted with PTBP1, thereby maintaining FOXP1 mRNA stability. Rescue assays demonstrated that FOXP1 upregulation reversed the inhibitory effects of silencing NEAT1 or PTBP1 on IL4/IL13-stimulated pyroptosis activation in HNEpCs.

CONCLUSION

NEAT1 acts as a RNA scaffold for PTBP1, activating the PTBP1/FOXP1 signaling cascade, subsequently triggering NLRP3-mediated pyroptosis in HNEpCs, and ultimately promoting AR progression. These findings highlight some new insights into the pathogenesis of AR.

Long noncoding RNA MALAT1 as a ceRNA drives mouse fibroblast activation via the miR-335-3p/P2ry2 axis

Fibrosis is a complex pathological process that can lead to the permanent loss of biological function, with P2ry2 playing a crucial role in this process. Long non-coding RNAs (lncRNAs) have been reported to play an critically important role in the fibrotic process. However, it remains unclear whether lncRNAs can regulate fibrosis through P2ry2. In this study, we detected the expression of the long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (lnc-MALAT1). We investigated the expression patterns of lnc-MALAT1 and P2ry2 in denervated skeletal muscle, a classical model of fibrosis. Additionally, we utilized a TGF-β-mediated fibrosis model in NIH/3T3 cells to examine the effects of lnc-MALAT1 and P2ry2 on fibroblast activation and the underlying regulatory mechanisms in vitro. Our results demonstrated that the expression levels of lnc-MALAT1 and P2ry2 were consistently elevated in denervated skeletal muscle, correlating with the degree of fibrosis. In vitro experiments confirmed the regulatory effect of lnc-MALAT1 on P2ry2. Furthermore, we identified miR-335-3p as a potential key molecule in the regulatory relationship of lnc-MALAT1/P2ry2. Dual luciferase reporter assays and AGO2-RIP verified the molecular sponging effect of lnc-MALAT1 on miR-335-3p. Additionally, we validated the regulation of the lnc-MALAT1/miR-335-3p/P2ry2 axis through experimental approaches. In conclusion, our study identified a crucial role of lnc-MALAT1/miR-335-3p/P2ry2 axis in fibroblast activation, providing a promising treatment option against the fibrosis.

Pharmacological mechanisms by which baicalin ameliorates cardiovascular disease

Baicalin is a flavonoid glycoside obtained from the dried root of Scutellaria baicalensis Georgi, which belongs to the Labiatae family. Accumulating evidence indicates that baicalin has favorable therapeutic effects on cardiovascular diseases. Previous studies have revealed the therapeutic effects of baicalin on atherosclerosis, myocardial ischemia/reperfusion injury, hypertension, and heart failure through anti-inflammatory, antioxidant, and lipid metabolism mechanisms. In recent years, some new ideas related to baicalin in ferroptosis, coagulation and fibrinolytic systems have been proposed, and new progress has been made in understanding the mechanism by which baicalin protects cardiomyocytes. However, many relevant underlying mechanisms remain unexplained, and much experimental data is lacking. Therefore, further research is needed to determine these mechanisms. In this review, we summarize the mechanisms of baicalin, which include its anti-inflammatory and antioxidant effects; inhibition of endothelial cell apoptosis; modulation of innate immunity; suppression of vascular smooth muscle cells proliferation, migration, and contraction; regulation of coagulation and fibrinolytic systems; inhibition of myocardial hypertrophy; prevention of myocardial fibrosis; and anti-apoptotic effects on cardiomyocytes.

Steatotic liver disease induced by TCPOBOP-activated hepatic constitutive androstane receptor: primary and secondary gene responses with links to disease progression

Constitutive androstane receptor (CAR, Nr1i3), a liver nuclear receptor and xenobiotic sensor, induces drug, steroid, and lipid metabolizing enzymes, stimulates liver hypertrophy and hyperplasia, and ultimately, hepatocellular carcinogenesis. The mechanisms linking early CAR responses to later disease development are poorly understood. Here we show that exposure of CD-1 mice to TCPOBOP (1,4-bis[2-(3,5-dichloropyridyloxy)]benzene), a halogenated xenochemical and selective CAR agonist ligand, induces pericentral steatosis marked by hepatic accumulation of cholesterol and neutral lipid, and elevated circulating alanine aminotransferase, indicating hepatocyte damage. TCPOBOP-induced steatosis was weaker in the pericentral region but stronger in the periportal region in females compared with males. Early (1 day) TCPOBOP transcriptional responses were enriched for CAR-bound primary response genes, and for lipogenesis and xenobiotic metabolism and oxidative stress protection pathways; late (2 weeks) TCPOBOP responses included many CAR binding-independent secondary response genes, with enrichment for macrophage activation, immune response, and cytokine and reactive oxygen species production. Late upstream regulators specific to TCPOBOP-exposed male liver were linked to proinflammatory responses and hepatocellular carcinoma progression. TCPOBOP administered weekly to male mice using a high corn oil vehicle induced carbohydrate-responsive transcription factor (MLXIPL)-regulated target genes, dysregulated mitochondrial respiratory and translation regulatory pathways, and induced more advanced liver pathology. Overall, TCPOBOP exposure recapitulates histological and gene expression changes characteristic of emerging steatotic liver disease, including secondary gene responses in liver nonparenchymal cells indicative of transition to a more advanced disease state. Upstream regulators of both the early and late TCPOBOP response genes include novel biomarkers for foreign chemical-induced metabolic dysfunction-associated steatotic liver disease.

Glycolytic enzyme PGK1 promotes M1 macrophage polarization and induces pyroptosis of acute lung injury via regulation of NLRP3

Acute lung injury (ALI) is characterized by an unregulated inflammatory reaction, often leading to severe morbidity and ultimately death. Excessive inflammation caused by M1 macrophage polarization and pyroptosis has been revealed to have a critical role in ALI. Recent study suggests that glycolytic reprogramming is important in the regulation of macrophage polarization and pyroptosis. However, the particular processes underlying ALI have yet to be identified. In this study, we established a Lipopolysaccharide(LPS)-induced ALI model and demonstrated that blocking glycolysis by using 2-Deoxy-D-glucose(2-DG) significantly downregulated the expression of M1 macrophage markers and pyroptosis-related genes, which was consistent with the in vitro results. Furthermore, our research has revealed that Phosphoglycerate Kinase 1(PGK1), an essential enzyme in the glycolysis pathway, interacts with NOD-, LRR- and pyrin domain-containing protein 3(NLRP3). We discovered that LPS stimulation improves the combination of PGK1 and NLRP3 both in vivo and in vitro. Interestingly, the absence of PGK1 reduces the phosphorylation level of NLRP3. Based on in vitro studies with mice bone marrow-derived macrophages (BMDMs), we further confirmed that siPGK1 plays a protective role by inhibiting macrophage pyroptosis and M1 macrophage polarization. The PGK1 inhibitor NG52 suppresses the occurrence of excessive inflammation in ALI. In general, it is plausible to consider a therapeutic strategy that focuses on modulating the relationship between PGK1 and NLRP3 as a means to mitigate the activation of inflammatory macrophages in ALI.

Spatial multiomics of arterial regions from cardiac allograft vasculopathy rejected grafts reveal novel insights into the pathogenesis of chronic antibody-mediated rejection

Cardiac allograft vasculopathy (CAV) causes late graft failure and mortality after heart transplantation. Donor-specific antibodies (DSAs) lead to chronic endothelial cell injury, inflammation, and arterial intimal thickening. In this study, GeoMx digital spatial profiling was used to analyze arterial areas of interest (AOIs) from CAV+DSA+ rejected cardiac allografts (N = 3; 22 AOIs total). AOIs were categorized based on CAV neointimal thickening and underwent whole transcriptome and protein profiling. By comparing our transcriptomic data with that of healthy control vessels of rapid autopsy myocardial tissue, we pinpointed specific pathways and transcripts indicative of heightened inflammatory profiles in CAV lesions. Moreover, we identified protein and transcriptomic signatures distinguishing CAV lesions exhibiting low and high neointimal lesions. AOIs with low neointima showed increased markers for activated inflammatory infiltrates, endothelial cell activation transcripts, and gene modules involved in metalloproteinase activation and TP53 regulation of caspases. Inflammatory and apoptotic proteins correlated with inflammatory modules in low neointima AOIs. High neointima AOIs exhibited elevated TGFβ-regulated transcripts and modules enriched for platelet activation/aggregation. Proteins associated with growth factors/survival correlated with modules enriched for proliferation/repair in high neointima AOIs. Our findings reveal novel insight into immunological mechanisms mediating CAV pathogenesis.

Specific deletion of Mettl3 in IECs triggers the development of spontaneous colitis and dysbiosis of T lymphocytes in mice

The enzymatic core component of m6A writer complex, Mettl3, plays a crucial role in facilitating the development and progress of gastric and colorectal cancer (CRC). However, its underlying mechanism in regulating intestinal inflammation remains unclear and poorly investigated. First, the characteristics of Mettl3 expression in inflammatory bowel diseases (IBD) patients were examined. Afterward, we generated the mice line with intestinal epithelial cells (IECs)-specific deletion of Mettl3 verified by various experiments. We continuously recorded and compared the physiological status including survival rate etc. between the two groups. Subsequently, we took advantage of staining assays to analyze mucosal damage and immune infiltration of Mettl3WT and Mettl3KO primary IECs. Bulk RNA sequencing was used to pursuit the differential expression of genes (DEGs) and associated signaling pathways after losing Mettl3. Pyroptosis-related proteins were to determine whether cell death was caused by pyroptosis. Eventually, CyTOF was performed to probe the difference of CD45+ cells, especially CD3e+ T-cell clusters after losing Mettl3. In IBD patients, Mettl3 was highly expressed in the inner-nucleus of IECs while significantly decreased upon acute intestinal inflammation. IECs-specific deletion of Mettl3 KO mice triggered a wasting phenotype and developed spontaneous colitis. The survival rate, body weight, and intestinal length observed from 2 to 8 weeks of Mettl3KO mice were significantly lower than Mettl3WT mice. The degree of mucosal damage and immune infiltration in Mettl3KO were even more serious than in their WT littermate. Bulk RNA sequencing demonstrated that DEGs were dramatically enriched in NOD-signaling pathways due to the loss of Mettl3. The colonic epithelium was more prone to pyroptosis after losing Mettl3. Subsequently, CyTOF revealed that T cells have altered significantly in Mettl3KO. Furthermore, there was abnormal proliferation of CD4+ T and markedly exhaustion of CD8 + T in Mettl3KO mice. In severe IBD patients, Mettl3 is located in the inner-nucleus of IECs and declined when intestinal inflammation occurs. Subsequently, Mettl3 prevented mice from developing colitis.

The role of RNA methylation in tumor immunity and its potential in immunotherapy

RNA methylation, a prevalent post-transcriptional modification, has garnered considerable attention in research circles. It exerts regulatory control over diverse biological functions by modulating RNA splicing, translation, transport, and stability. Notably, studies have illuminated the substantial impact of RNA methylation on tumor immunity. The primary types of RNA methylation encompass N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N7-methylguanosine (m7G), and 3-methylcytidine (m3C). Compelling evidence underscores the involvement of RNA methylation in regulating the tumor microenvironment (TME). By affecting RNA translation and stability through the "writers", "erasers" and "readers", RNA methylation exerts influence over the dysregulation of immune cells and immune factors. Consequently, RNA methylation plays a pivotal role in modulating tumor immunity and mediating various biological behaviors, encompassing proliferation, invasion, metastasis, etc. In this review, we discussed the mechanisms and functions of several RNA methylations, providing a comprehensive overview of their biological roles and underlying mechanisms within the tumor microenvironment and among immunocytes. By exploring how these RNA modifications mediate tumor immune evasion, we also examine their potential applications in immunotherapy. This review aims to provide novel insights and strategies for identifying novel targets in RNA methylation and advancing cancer immunotherapy efficacy.

Disulfiram Improves Fat Graft Retention by Modulating Macrophage Polarization With Inhibition of NLRP3 Inflammasome-Mediated Pyroptosis

BACKGROUND

Macrophage-mediated inflammatory response in the early post-grafting period restricts fat graft retention. Pyroptosis is a novel type of programmed cell death that extensively participates in inflammatory pathologies.

OBJECTIVES

This study sought to determine whether macrophage pyroptosis was activated during the inflammatory phase after fat grafting and to investigate the efficacy of a pyroptosis inhibitor, disulfiram (DSF), in fat graft retention.

METHODS

We established a C57BL/6 mice fat grafting model and then analyzed macrophage pyroptosis. DSF (50 mg/kg, every other day) was intraperitoneally injected starting 1 hour before fat grafting and continued for 14 days. An in vitro co-culture system was established in which mouse RAW264.7 macrophages were co-cultured with apoptotic adipocytes to further validate the findings of the in vivo studies and to explore the underlying mechanisms.

RESULTS

Here we reported that macrophage pyroptosis was activated in both fat grafts and in vitro co-culture models. DSF was found to be a potent pyroptosis inhibitor, promoting M2 macrophage polarization. In addition, DSF was demonstrated to enhance vascularization and graft retention.

CONCLUSIONS

Our results suggested that pyroptosis plays a crucial role in the inflammatory cascade within fat grafts. DSF, being a clinically available drug, could be translated into a clinically effective drug for improving fat graft survival by inhibiting macrophage pyroptosis, therefore inducing M2 macrophage polarization and promoting neovascularization.

N6-methyladenosine-dependent signaling in colorectal cancer: Functions and clinical potential

Colorectal cancer (CRC) ranks as the third most prevalent malignancy worldwide. Despite the gradual expansion of therapeutic options for CRC, its clinical management remains a formidable challenge. And, because of the current dearth of technical means for early CRC screening, most patients are diagnosed at an advanced stage. Therefore, it is imperative to develop novel diagnostic and therapeutic tools for this disease. N6-methyladenosine (m6A), the predominant RNA modification in eukaryotes, can be recognized by m6A-specific methylated reading proteins to modulate gene expression. Studies have revealed that CRC disrupts m6A homeostasis through various mechanisms, thereby sustaining aberrant signal transduction and promoting its own progression. Consequently, m6A-based diagnostic and therapeutic strategies have garnered widespread attention. Although utilizing m6A as a biomarker and drug target has demonstrated promising feasibility, existing observations primarily stem from preclinical models; henceforth necessitating further investigation and resolution of numerous outstanding issues.

Determining toxicity of europium oxide nanoparticles in immune cell components and hematopoiesis in dominant organs in mice: Role of lysosomal fluid interaction

Extensive application of rare earth element oxide nanoparticles (REE NPs) has raised a concern over the possible toxic health effects after human exposure. Once entering the body, REE NPs are primarily processed by phagocytes in particular macrophages and undergo biotic phosphate complexation in lysosomal compartment. Such biotransformation affects the target organs and in vivo fate of REE NPs after escaping the lysosomes. However, the immunomodulatory effects of intraphagolysosomal dissolved REE NPs remains insufficient. Here, europium oxide (Eu2O3) NPs were pre-incubated with phagolysosomal simulant fluid (PSF) to mimic the biotransformation of europium oxide (p-Eu2O3) NPs under acid phagolysosome conditions. We investigated the alteration in immune cell components and the hematopoiesis disturbance on adult mice after intravenous administration of Eu2O3 NPs and p-Eu2O3 NPs. Our results indicated that the liver and spleen were the main target organs for Eu2O3 NPs and p-Eu2O3 NPs. Eu2O3 NPs had a much higher accumulative potential in organs than p-Eu2O3 NPs. Eu2O3 NPs induced more alterations in immune cells in the spleen, while p-Eu2O3 NPs caused stronger response in the liver. Regarding hematopoietic disruption, Eu2O3 NPs reduced platelets (PLTs) in peripheral blood, which might be related to the inhibited erythrocyte differentiation in the spleen. By contrast, p-Eu2O3 NPs did not cause significant disturbance in peripheral PLTs. Our study demonstrated that the preincubation with PSF led to a distinct response in the immune system compared to the pristine REE NPs, suggesting that the potentially toxic effects induced by the release of NPs after phagocytosis should not be neglected, especially when evaluating the safety of NPs application in vivo.

Suppression of the JAK/STAT Pathway Inhibits Neuroinflammation in the Line 61-PFF Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is characterized by neuroinflammation, progressive loss of dopaminergic neurons, and accumulation of a-synuclein (a-Syn) into insoluble aggregates called Lewy pathology. The Line 61 a-Syn mouse is an established preclinical model of PD; Thy-1 is used to promote human a-Syn expression, and features of sporadic PD develop at 9-18 months of age. To accelerate the PD phenotypes, we injected sonicated human a-Syn preformed fibrils (PFFs) into the striatum, which produced phospho-Syn (p-a-Syn) inclusions in the substantia nigra pars compacta and significantly increased MHC Class II-positive immune cells. Additionally, there was enhanced infiltration and activation of innate and adaptive immune cells in the midbrain. We then used this new model, Line 61-PFF, to investigate the effect of inhibiting the JAK/STAT signaling pathway, which is critical for regulation of innate and adaptive immune responses. After administration of the JAK1/2 inhibitor AZD1480, immunofluorescence staining showed a significant decrease in p-a-Syn inclusions and MHC Class II expression. Flow cytometry showed reduced infiltration of CD4+ T-cells, CD8+ T-cells, CD19+ B-cells, dendritic cells, macrophages, and endogenous microglia into the midbrain. Importantly, single-cell RNA-Sequencing analysis of CD45+ cells from the midbrain identified 9 microglia clusters, 5 monocyte/macrophage (MM) clusters, and 5 T-cell (T) clusters, in which potentially pathogenic MM4 and T3 clusters were associated with neuroinflammatory responses in Line 61-PFF mice. AZD1480 treatment reduced cell numbers and cluster-specific expression of the antigen-presentation genes H2-Eb1, H2-Aa, H2-Ab1, and Cd74 in the MM4 cluster and proinflammatory genes such as Tnf, Il1b, C1qa, and C1qc in the T3 cluster. Together, these results indicate that inhibiting the JAK/STAT pathway suppresses the activation and infiltration of innate and adaptive cells, reducing neuroinflammation in the Line 61-PFF mouse model.

METTL3-deficiency m6A-dependently degrades MALAT1 to suppress NLRP3-mediated pyroptotic cell death and inflammation in Mycobacterium tuberculosis (H37Ra strain)-infected mouse macrophages

Mycobacterium tuberculosis (Mtb)-infected macrophages aggravated the development of pulmonary tuberculosis, but its detailed molecular mechanisms are still largely unknown. Here, the mouse primary peritoneal macrophages were infected with the attenuated strain of Mtb H37Ra, and we firstly verified that targeting a novel METTL3/N6-Methyladenosine (m6A)/LncRNA MALAT1/miR-125b/TLR4 axis was effective to suppress pyroptotic cell death in the Mtb-infected macrophages. Specifically, through performing Real-Time qPCR and Western Blot analysis, we validated that METTL3, LncRNA MALAT1 and TLR4 were elevated, whereas miR-125b and the anti-oxidant agents (Nrf2 and HO-1) were downregulated in Mtb-infected mouse macrophages. In addition, functional experiments confirmed that both ROS scavenger NAC and METTL3-ablation downregulated NLRP3, GSDMD-C, cleaved Caspase-1 and ASC to restrain pyroptotic cell death and decreased the expression levels of IL-1β, IL-18, IL-6 and TNF-α to restrain inflammatory cytokines expression in Mtb-infected macrophages. Next, METTL3-ablation induced m6A-demethylation and instability in LncRNA MALAT1, and low-expressed LncRNA MALAT1 caused TLR4 downregulation through sponging miR-125b, resulting in the inactivation of NLRP3 inflammasome. Finally, silencing of METTL3-induced protective effects in Mtb-infected macrophages were all abrogated by overexpressing LncRNA MALAT1 and downregulating miR-125b. Thus, we concluded that targeting METTL3-mediated m6A modifications suppressed Mtb-induced pyroptotic cell death in mouse macrophages, and the downstream LncRNA MALAT1/miR-125b/TLR4 axis played critical role in this process.

N6-methyladenosine in myeloid cells: a novel regulatory factor for inflammation-related diseases

N6-methyladenosine (m6A) is one of the most abundant epitranscriptomic modifications on eukaryotic mRNA. Evidence has highlighted that m6A is altered in response to inflammation-related factors and it is closely associated with various inflammation-related diseases. Multiple subpopulations of myeloid cells, such as macrophages, dendritic cells, and granulocytes, are crucial for the regulating of immune process in inflammation-related diseases. Recent studies have revealed that m6A plays an important regulatory role in the functional of multiple myeloid cells. In this review, we comprehensively summarize the function of m6A modification in myeloid cells from the perspective of myeloid cell production, activation, polarization, and migration. Furthermore, we discuss how m6A-mediated myeloid cell function affects the progression of inflammation-related diseases, including autoimmune diseases, chronic metabolic diseases, and malignant tumors. Finally, we discuss the challenges encountered in the study of m6A in myeloid cells, intended to provide a new direction for the study of the pathogenesis of inflammation-related diseases.

N6-Methyladenosine Demethylase ALKBH5 Promotes Pyroptosis by Modulating PTBP1 mRNA Stability in LPS-Induced Myocardial Dysfunction

Objective

This study aims to investigate the mechanism by which alkB homolog 5 (ALKBH5) regulates polypyrimidine tract-binding protein 1 (PTBP1) to mediate cardiomyocyte pyroptosis in sepsis-induced myocardial injury.

Methods

Lipopolysaccharide (LPS)-exposed H9C2 cell and rat models were established to mimic septic myocardial injury both in vitro and in vivo. The mRNA and protein levels of ALKBH5 and PTBP1 in the LPS-induced cell and septic rat models were detected. CCK-8 and flow cytometry were applied to detect cell viability and pyroptosis. H&E staining was used to observe myocardial tissue damage in rats, and immunohistochemistry to analyze the expression of pyroptosis and inflammation-related proteins in rat tissues.

Results

Elevated expressions of both ALKBH5 and PTBP1 were found in the myocardial tissues of LPS-induced septic rats. ALKBH5 knockdown could restore the cell viability and cell pyroptosis inhibited by LPS, while ALKBH5 promoted PTBP1 mRNA stability by affecting its N6-methyladenosine (m6A) modification. In vivo experiments showed that PTBP1 knockdown could largely reverse the antiproliferative and pro-pyroptosis effects of ALKBH5 in LPS-exposed H9C2 cells. ALKBH5 knockdown in in vivo experiments was found to suppress the expressions of pyroptosis biomarkers and attenuate myocardial injury in septic rats.

Conclusions

ALKBH5 promoted mRNA stability and the expression of PTBP1 through m6A modification to induce pyroptosis in cardiomyocytes and ultimately aggravate sepsis-induced myocardial dysfunction.

Obesity phenotype induced by high-fat diet promotes diethylnitrosamine (DEN)-induced precancerous lesions by M1 macrophage polarization in mice liver

Liver precancerous lesions are the key to improving the efficacy of cancer treatment because of the extremely poor prognosis of HCC patients in moderate and late stages. Obesity-related HCC progression is closely related to the inflammatory microenvironment, in which macrophages are one of the major constituents. In the present study, we ask whether obesity promotes diethylnitrosamine (DEN)-induced precancerous lesions by M1 macrophage polarization. First, an association between obesity and liver precancerous lesions was determined by histopathological observations, immunochemistry and immunoblotting. The characteristics of early precancerous lesions (trabecular thickening) appeared earlier eight weeks in obese mice than in normal diet mice after DEN induction. The glutathione S-transferase placental-1 (Gstp 1) and alpha-fetoprotein (AFP) expression in obese mice after DEN induction was higher than that in the same period after DEN injection in normal diet mice. Furthermore, there was a significant increase in the total macrophage number (F4/80+) of DEN and M1 macrophage number (CD86+F4/80+) in obese mice compared with that in normal diet mice. Besides, the expressions of four pro-inflammatory factors in DEN-induced obese mice were significantly higher compared with that in normal diet mice. Additionally, angiogenesis was revealed by immunostaining assay to be associated with the inflammatory response. All the results demonstrate that obesity promotes DEN-induced precancerous lesions by inducing M1 macrophage polarization and angiogenesis.

Unveiling the flames: macrophage pyroptosis and its crucial role in liver diseases

Macrophages play a critical role in innate immunity, with approximately 90% of the total macrophage population in the human body residing in the liver. This population encompasses both resident and infiltrating macrophages. Recent studies highlight the pivotal role of liver macrophages in various aspects such as liver inflammation, regeneration, and immune regulation. A novel pro-inflammatory programmed cell death, pyroptosis, initially identified in macrophages, has garnered substantial attention since its discovery. Studies investigating pyroptosis and inflammation progression have particularly centered around macrophages. In liver diseases, pyroptosis plays an important role in driving the inflammatory response, facilitating the fibrotic process, and promoting tumor progression. Notably, the role of macrophage pyroptosis cannot be understated. This review primarily focuses on the role of macrophage pyroptosis in liver diseases. Additionally, it underscores the therapeutic potential inherent in targeting macrophage pyroptosis.

The role of N6-methyladenosine in macrophage polarization: A novel treatment strategy for non-alcoholic steatohepatitis

RNA methylation modifications, as a widespread type of modification in eukaryotic cells, especially N6-methyladenosine (m6A), are associated with many activities in organisms, including macrophage polarization and progression of non-alcoholic steatohepatitis (NASH). Macrophages in the liver are of diverse origin and complex phenotype, exhibiting different functions in development of NASH. In the review, we discuss the functions of m6A and m6A-related enzymes in macrophage polarization. Furthermore, we retrospect the role of macrophage polarization in NASH. Finally, we discuss the prospects of m6A in macrophages and NASH, and provide guidance for the treatment of NASH.

Invertebrate Immunity, Natural Transplantation Immunity, Somatic and Germ Cell Parasitism, and Transposon Defense

While the vertebrate immune system consists of innate and adaptive branches, invertebrates only have innate immunity. This feature makes them an ideal model system for studying the cellular and molecular mechanisms of innate immunity sensu stricto without reciprocal interferences from adaptive immunity. Although invertebrate immunity is evolutionarily older and a precursor of vertebrate immunity, it is far from simple. Despite lacking lymphocytes and functional immunoglobulin, the invertebrate immune system has many sophisticated mechanisms and features, such as long-term immune memory, which, for decades, have been exclusively attributed to adaptive immunity. In this review, we describe the cellular and molecular aspects of invertebrate immunity, including the epigenetic foundation of innate memory, the transgenerational inheritance of immunity, genetic immunity against invading transposons, the mechanisms of self-recognition, natural transplantation, and germ/somatic cell parasitism.

Salvianolic Acid B Alleviates Liver Injury by Regulating Lactate-Mediated Histone Lactylation in Macrophages

Salvianolic acid B (Sal B) is the primary water-soluble bioactive constituent derived from the roots of Salvia miltiorrhiza Bunge. This research was designed to reveal the potential mechanism of Sal B anti-liver injury from the perspective of macrophages. In our lipopolysaccharide-induced M1 macrophage model, Sal B showed a clear dose-dependent gradient of inhibition of the macrophage trend of the M1 type. Moreover, Sal B downregulated the expression of lactate dehydrogenase A (LDHA), while the overexpression of LDHA impaired Sal B's effect of inhibiting the trend of macrophage M1 polarization. Additionally, this study revealed that Sal B exhibited inhibitory effects on the lactylation process of histone H3 lysine 18 (H3K18la). In a ChIP-qPCR analysis, Sal B was observed to drive a reduction in H3K18la levels in the promoter region of the LDHA, NLRP3, and IL-1β genes. Furthermore, our in vivo experiments showed that Sal B has a good effect on alleviating CCl4-induced liver injury. An examination of liver tissues and the Kupffer cells isolated from those tissues proved that Sal B affects the M1 polarization of macrophages and the level of histone lactylation. Together, our data reveal that Sal B has a potential mechanism of inhibiting the histone lactylation of macrophages by downregulating the level of LDHA in the treatment of liver injury.

Mitochondrial-mediated nuclear remodeling and macrophage polarizations: A key switch from liver fibrosis to HCC progression

Liver fibrosis is a significant health burden worldwide and has emerged as the leading cause of Hepatocellular carcinoma (HCC) incidence. Mitochondria are the dynamic organelles that regulate the differentiation, survival, and polarization of macrophages. Nuclear-DNA-associated proteins, micro-RNAs, as well as macrophage polarization are essential for maintaining intracellular and extra-cellular homeostasis in the liver parenchyma. Dysregulated mitochondrial coding genes (ETS complexes I, II, III, IV, and V), non-coding RNAs (mitomiRs), and nuclear alteration lead to the production of reactive oxygen species (ROS) and inflammation which are implicated in the transition of liver fibrosis into HCC. Recent findings indicated the protecting effect of E74-like factor 3/peroxisome proliferator-activated receptor-γ (Elf-3/PPAR-γ). HDAR-y inhibits the deacetylation of PPAR-y and maintains the PPAR-y pathway. Elf-3 plays a tumor suppressive role through epithelial-mesenchymal transition-related gene and zinc finger E-box binding homeobox 2 (ZEB-2) domain. Additionally, the development of HCC includes the PI3K/Akt/mTOR and transforming Growth Factor β (TGF-β) pathway that promotes the Epithelial-mesenchymal transition (EMT) through Smad/Snail/Slug signaling cascade. In contrast, the TLR2/NOX2/autophagy axis promotes M2 polarization in HCC. Thus, a thorough understanding of the mitochondrial and nuclear reciprocal relationship related to macrophage polarization could provide new research opportunities concerning diseases with a significant impact on liver parenchyma towards developing liver fibrosis or liver cancer. Moreover, this knowledge can be used to develop new therapeutic strategies to treat liver diseases.

m6A methylation modification and immune cell infiltration: implications for targeting the catalytic subunit m6A-METTL complex in gastrointestinal cancer immunotherapy

N6-methyladenosine (m6A) methylation modification is a ubiquitous RNA modification involved in the regulation of various cellular processes, including regulation of RNA stability, metabolism, splicing and translation. Gastrointestinal (GI) cancers are some of the world's most common and fatal cancers. Emerging evidence has shown that m6A modification is dynamically regulated by a complex network of enzymes and that the catalytic subunit m6A-METTL complex (MAC)-METTL3/14, a core component of m6A methyltransferases, participates in the development and progression of GI cancers. Furthermore, it has been shown that METTL3/14 modulates immune cell infiltration in an m6A-dependent manner in TIME (Tumor immune microenvironment), thereby altering the response of cancer cells to ICIs (Immune checkpoint inhibitors). Immunotherapy has emerged as a promising approach for treating GI cancers. Moreover, targeting the expression of METTL3/14 and its downstream genes may improve patient response to immunotherapy. Therefore, understanding the role of MAC in the pathogenesis of GI cancers and its impact on immune cell infiltration may provide new insights into the development of effective therapeutic strategies for GI cancers.

Emerging role of m6A modification in fibrotic diseases and its potential therapeutic effect

Fibrosis can occur in a variety of organs such as the heart, lung, liver and kidney, and its pathological changes are mainly manifested by an increase in fibrous connective tissue and a decrease in parenchymal cells in organ tissues, and continuous progression can lead to structural damage and organ hypofunction, or even failure, seriously threatening human health and life. N6-methyladenosine (m6A) modification, as one of the most common types of internal modifications of RNA in eukaryotes, exerts a multifunctional role in physiological and pathological processes by regulating the metabolism of RNA. With the in-depth understanding and research of fibrosis, we found that m6A modification plays an important role in fibrosis, and m6A regulators can further participate in the pathophysiological process of fibrosis by regulating the function of specific cells. In our review, we summarized the latest research advances in m6A modification in fibrosis, as well as the specific functions of different m6A regulators. In addition, we focused on the mechanisms and roles of m6A modification in cardiac fibrosis, liver fibrosis, pulmonary fibrosis, renal fibrosis, retinal fibrosis and oral submucosal fibrosis, with the aim of providing new insights and references for finding potential therapeutic targets for fibrosis. Finally, we discussed the prospects and challenges of targeted m6A modification in the treatment of fibrotic diseases.

Isovitexin alleviates hepatic fibrosis by regulating miR-21-mediated PI3K/Akt signaling and glutathione metabolic pathway: based on transcriptomics and metabolomics

BACKGROUND

Effective drugs for the treatment of hepatic fibrosis have not yet been identified. Isovitexin (IVT) is a promising hepatoprotective agent owing to its efficacy against acute liver injury. However, the role of IVT in liver fibrosis has not been reported.

PURPOSE

To explore the effect of IVT on liver fibrosis both in vitro and in vivo.

STUDY DESIGN AND METHODS

A mouse model of liver fibrosis induced by carbon tetrachloride (CCl4) and two types of hepatic stellate cell models induced by platelet-derived growth factor-BB (PDGF-BB) were established to evaluate the effect of IVT on hepatic fibrosis. Transcriptomics and metabolomics were used to predict the underlying targets of IVT and were validated by a combination of in vitro and in vivo experiments. Exploration of miRNA and N6-methyladenosine (m6A) modifications was also carried out to detect the key upstream targets of the above targets.

RESULTS

IVT reduced collagen deposition and hepatic stellate cell activation to alleviate liver fibrosis. The transcriptomics and metabolomics analyses showed that phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling and the glutathione (GSH) metabolic pathway may be the main regulatory processes of IVT in hepatic fibrosis. Both the in vitro and in vivo experiments confirmed the inhibitory effect of IVT on the PTEN-PI3K-Akt-mTOR axis and activation of the GSH metabolic pathway. A miR-21 mimic inhibited the effects of IVT on these two pathways, suggesting that miR-21 is the hub for IVT regulation of PI3K-Akt signaling and the GSH metabolic pathway. IVT also increased pri-miR-21 level and reduced the m6A enrichment of pri-miR-21, demonstrating that IVT may regulate pri-miR-21 through m6A modification, thereby affecting the maturation of miR-21.

CONCLUSION

This study is the first to propose a protective effect of IVT against liver fibrosis. The mechanism of IVT against hepatic fibrosis is based on the regulation of miR-21, targeting PTEN-Akt signaling and the GSH metabolic pathway, which is also a novel discovery.

Do RNA modifications contribute to modulation of immune responses in allergic diseases?

RNA modifications have emerged as a fundamental mechanism of post-transcriptional gene regulation, playing vital roles in cellular physiology and the development of various diseases. While the investigation of RNA modifications has seen significant advancements, the exploration of their implication in allergic diseases has been comparatively overlooked. Allergic reactions, including hay fever, asthma, eczema and food allergies, result from hypersensitive immune responses, affecting a considerable population worldwide. Despite the high prevalence, the molecular mechanisms underlying these responses remain partially understood. The potential role of RNA modifications in modulating the hypersensitive immune responses has yet to be fully elucidated. This mini-review seeks to shed light on potential connections between RNA modifications and allergy, highlighting recent findings and potential future research directions. By expanding our understanding of the complex interplay between RNA modifications and allergic responses, we hope to unlock new avenues for allergy diagnosis, prognosis, and therapeutic intervention.

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.

The role and mechanisms of macrophage polarization and hepatocyte pyroptosis in acute liver failure

Acute liver failure (ALF) is a severe liver disease caused by disruptions in the body's immune microenvironment. In the early stages of ALF, Kupffer cells (KCs) become depleted and recruit monocytes derived from the bone marrow or abdomen to replace the depleted macrophages entering the liver. These monocytes differentiate into mature macrophages, which are activated in the immune microenvironment of the liver and polarized to perform various functions. Macrophage polarization can occur in two directions: pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages. Controlling the ratio and direction of M1 and M2 in ALF can help reduce liver injury. However, the liver damage caused by pyroptosis should not be underestimated, as it is a caspase-dependent form of cell death. Inhibiting pyroptosis has been shown to effectively reduce liver damage induced by ALF. Furthermore, macrophage polarization and pyroptosis share common binding sites, signaling pathways, and outcomes. In the review, we describe the role of macrophage polarization and pyroptosis in the pathogenesis of ALF. Additionally, we preliminarily explore the relationship between macrophage polarization and pyroptosis, as well as their effects on ALF.

[METTL3 inhibitor STM2457 improves metabolic dysfunction-associated fatty liver disease by regulating mitochondrial function in mice]

OBJECTIVE

To investigate the effect of methyltransferase-like 3 (METTL3) inhibitor STM2457 in metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

C57BL/6J mouse models of MAFLD induced by high-fat diet feeding for 16 weeks were treated with intraperitoneal injections of STM2457 (50 mg/kg) for 2 weeks. The changes in m6A modification level in the liver tissue of the mice were determined with dot-blot hybridization, and the hepatic levels of triglyceride (TG), alanine aminotransferase (ALT) and glutathione aminotransferase (AST) were detected. The histological changes of the liver and changes in insulin resistance and metabolic profile of the mice were evaluated using HE staining, insulin tolerance tests and metabolic cages; transmission electron microscopy (TEM) was employed to examine the changes in mitochondrial morphology. In a HepG2 cell model of steatosis induced by treatment with sodium oleate/sodium palmitate for 48 h, the protective effect of STM2457 (1 μmol/L) on mitochondrial function was assessed by measuring mitochondrial membrane potential using a fluorescence probe (JC-1).

RESULTS

The mouse models of MAFLD showed significant elevation of m6A modification level in the liver tissues and obviously upregulated mRNA expression of METT3 (P<0.05). Treatment with STM2457 significantly reduced body weight and liver lipid deposition and m6A modification levels, increased glucose tolerance and insulin sensitivity, lowered hepatic TG and serum ALT and AST levels, and increased respiratory entropy (RQ) in the mouse models (all P<0.05). HepG2 cells with steatosis exhibited obvious mitochondrial swelling with decreased mitochondrial membrane potential, but the STM2457-treated cells maintained a normal mitochondrial morphology with a higher membrane potential (P<0.05).

CONCLUSION

The METTL3 inhibitor STM2457 improves MAFLD by reducing high-fat diet-induced mitochondrial damage in mice.

Malat1 promotes macrophage-associated inflammation by increasing PPAR-γ methylation through binding to EZH2 in acute myocardial infarction

The inflammatory microenvironment of macrophage plays an important role in acute myocardial infarction (AMI), but the regulatory mechanism is unknown. Here, we aimed to investigate the role of Malat1 on inflammation microenvironment of macrophage in AMI. Our study found that Malat1 expression was increased in AMI, which mainly expressed in macrophages. Malat1 inhibition improved collagen deposition and inflammation in infarcted heart. In vitro, Malat1 inhibition evidently reduced macrophage-associated inflammation. The results from ribonucleic acid pull-down (RNA pull-down) and RNA Immunoprecipitation (RIP) assay demonstrated that Malat1 directly binds to EZH2. Malat1 and EZH2 complex could increase histone H3K27me3 expression and further inhibit the production of PPAR-γ. In vivo, inhibition of Malat1 also leaded to the down-regulation of both EZH2 and H3K27me3, as well as up-regulation of PPAR-γ in infarcted heart. Therefore, these findings demonstrate a novel mechanism of Malat1 on inflammation microenvironment of macrophage in AMI, which provide a new target for its treatment.

Remimazolam relieved the injury of hypoxia/reperfusion treated human embryo liver cell line through the targeting METTL3 mediated m6A modification of P53

Background

This study was performed to explore the role of Re in liver IRI progression. Hypoxia and reperfusion (H/R) treated human embryo liver cell line (L-02) was used to establish a liver IRI model.

Materials and methods

Cell behaviors were detected using CCK-8, flow cytometry and TUNEL staining assays. The m6A content was detected using m6A dot blot assay. RT-qPCR and western blot assays were used to assessed the relative mRNA and protein levels. MeRIP assay was conducted to determine the m6A levels of P53. The relationship between METTL3 and P53 was demonstrated using RIP and dual-luciferase reporter assays.

Results

The results showed that Re treatment significantly decreased the cell apoptosis and promoted the cell viability in the H/R treated L-02 cells. Besides, H/R treatment increased the METTL3 and m6A levels in the L-02 cells, and Re treatment decreased them. Additionally, METTL3 overexpression reversed the role of Re in the H/R treated L-02 cells. Mechanistically, METTL3 overexpression enhanced the m6A levels and mRNA stability and expressions of P53. The combination of METTL3 and P53 was further confirmed.

Conclusion

In conclusion, this study demonstrated that Re treatment relieved the H/R induced injury in the L-02 cells through decreasing the METTL3 levels. METTL3 enhanced the mRNA stability and expressions of P53 through m6A modification. Re-METTL3-P53 axis might a new direction for the treatment of liver IRI in the future.

Programmed Cell Death in Liver Fibrosis

Programmed cell death (PCD) is a comprehensive term that encompasses various forms of cell death, such as apoptosis, necroptosis, pyroptosis, ferroptosis, and autophagy, which play a crucial role in the pathogenesis of liver fibrosis. PCD facilitates the elimination of aberrant cells, particularly activated hepatic stellate cells (HSCs), which are the primary producers of extracellular matrix (ECM). The removal of HSCs may impede ECM synthesis, thereby mitigating liver fibrosis. As such, PCD has emerged as a promising therapeutic target for the development of novel drugs to treat liver fibrosis. Numerous studies have been conducted to investigate the underlying mechanisms of PCD in the elimination of activated HSCs and other aberrant liver cells in fibrotic liver tissue, including hepatocytes, hepatic sinusoid endothelial cells (LSECs), and Kupffer cells (KCs). The induction of PCD, the interplay between different forms of PCD, and the potential harm or benefit of PCD in liver fibrosis are topics of ongoing research. Evidences suggest that PCD is a complex process with dual effects on liver fibrosis. The purpose of this review is to summarize the most recent advances in PCD and liver fibrosis research.

Emerging role of METTL3 in inflammatory diseases: mechanisms and therapeutic applications

Despite improvements in modern medical therapies, inflammatory diseases, such as atherosclerosis, diabetes, non-alcoholic fatty liver, chronic kidney diseases, and autoimmune diseases have high incidence rates, still threaten human health, and represent a huge financial burden. N6-methyladenosine (m6A) modification of RNA contributes to the pathogenesis of various diseases. As the most widely discussed m6A methyltransferase, the pathogenic role of METTL3 in inflammatory diseases has become a research hotspot, but there has been no comprehensive review of the topic. Here, we summarize the expression changes, modified target genes, and pathogenesis related to METTL3 in cardiovascular, metabolic, degenerative, immune, and infectious diseases, as well as tumors. In addition to epithelial cells, endothelial cells, and fibroblasts, METTL3 also regulates the function of inflammation-related immune cells, including macrophages, neutrophils, dendritic cells, Th17 cells, and NK cells. Regarding therapeutic applications, METTL3 serves as a target for the treatment of inflammatory diseases with natural plant drug components, such as emodin, cinnamaldehyde, total flavonoids of Abelmoschus manihot, and resveratrol. This review focuses on recent advances in the initiation, development, and therapeutic application of METTL3 in inflammatory diseases. Knowledge of the specific regulatory mechanisms involving METTL3 can help to deepen understanding of inflammatory diseases and lay the foundation for the development of precisely targeted drugs to address inflammatory processes.

N6-methyladenosine RNA methylation in liver diseases: from mechanism to treatment

Epigenetic modification occurring in RNA has become the hotspot of the field. N6-methyladenosine (m6A) methylation is the most abundant RNA internal modification mainly occurring at the consensus motif DR (m6A) CH (D = A/G/U, R = A/G, H = A/C/U) in the 3'-UTR particularly the region near stop codons. The life cycle of m6A methylation includes "writers," "erasers," and "readers", which are responsible for the addition, removal, and recognition of m6A, respectively. m6A modification has been reported changing RNA secondary structure or modulating the stability, localization, transport, and translation of mRNAs to play crucial roles in various physiological and pathological conditions. Liver, as the largest metabolic and digestive organ, modulates vital physiological functions, and its dysfunction gives rise to the occurrence of various diseases. Despite the advanced intervening measures, mortality due to liver diseases is continuously high. Recent studies have explored the roles of m6A RNA methylation in the pathogenesis of liver diseases, providing new insights for studying the molecular mechanism of liver diseases. In the review, we extensively summarize the life cycle of m6A methylation, as well as its function and relevant mechanisms in liver fibrosis (LF), nonalcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), hepatitis virus infection, and hepatocellular carcinoma (HCC), and eventually we explore the potential of m6A as a treatment option for these liver diseases.

Combined exposure to benzo(a)pyrene and dibutyl phthalate aggravates pro-inflammatory macrophage polarization in spleen via pyroptosis involving cathepsin B

Humans are often simultaneously exposed to benzo(a)pyrene (BaP) and dibutyl phthalate (DBP) through consumption of food and water. Yet, direct evidence of the link between BaP and DBP co-exposure and the risk of splenic injury is lacking. In the present study, we established the rats and primary splenic macrophages models to evaluate the effects of BaP or/and DBP exposure on spleen and underlying mechanisms. Compared to the single exposure or control groups, the co-exposure group showed more severe spleen damage and higher production of pro-inflammatory cytokines. Co-exposure to BaP and DBP resulted in a 1.79-fold, 2.11-fold and 1.9-fold increase in the M1 macrophage markers iNOS, NLRP3 (pyroptosis marker protein) and cathepsin B (CTSB), respectively, and a 0.8-fold decrease in the M2 macrophage marker Arg1 in vivo. The more prominent effects in perturbation of imbalance in M1/M2 polarization (iNOS, 2.25-fold; Arg1, 0.55-fold), pyroptosis (NLRP3, 1.43-fold), and excess CTSB (1.07-fold) in macrophages caused by BaP and DBP co-exposure in vitro were also found. Notably, MCC950 (the NLRP3-specific inhibitor) treatment attenuated the pro-inflammatory macrophage polarization and following pro-inflammatory cytokine production triggered by BaP and DBP co-exposure. Furthermore, CA-074Me (the CTSB-specific inhibitor) suppressed the macrophages pyroptosis, pro-inflammatory macrophage polarization, and secretion of pro-inflammatory cytokine induced by BaP and DBP co-exposure. In conclusion, this study indicates co-exposure to BaP and DBP poses a higher risk of spleen injury. Pro-inflammatory macrophage polarization regulated by pyroptosis involving CTSB underlies the spleen injury caused by BaP and DBP co-exposure.

RNA methylations in hepatic fibrosis, a gradually emerging new treatment strategy

BACKGROUND

Hepatic fibrosis (HF) is a pathological process caused by excessive accumulation of extracellular matrix caused by a series of causes, leading to the formation of fiber scar. RNA methylation is a newly discovered epigenetic modification that exists widely in eukaryotes and prokaryotes and plays a crucial role in the pathogenesis of many diseases.

RESULTS

The occurrence and development of HF are regulated by many factors, including excessive deposition of extracellular matrix, activation of hepatic stellate cells, inflammation, and oxidative stress. RNA methylations of different species have become a crucial regulatory mode of transcript expression, And participate in the pathogenesis of tumors, nervous system diseases, autoimmune diseases, and other diseases. In addition, there are five common types of RNA methylation, but only m6A plays a crucial regulatory role in HF. The pathophysiological regulation of m6A on HF is achieved by the combination of the methylated transferase, demethylated enzyme, and methylated reading protein.

CONCLUSIONS

RNA methylated methyltransferase, demethylase, and reading protein extensively affect the pathological mechanism of HF, which may be a new therapeutic and diagnostic target, representing a new class of therapeutic strategies.

Role of m6A modification in immune microenvironment of digestive system tumors

Digestive system tumors are huge health problem worldwide, largely attributable to poor dietary choices. The role of RNA modifications in cancer development is an emerging field of research. RNA modifications are associated with the growth and development of various immune cells, which, in turn, regulate the immune response. The majority of RNA modifications are methylation modifications, and the most common type is the N6-methyladenosine (m6A) modification. Here, we reviewed the molecular mechanism of m6A in the immune cells and the role of m6A in the digestive system tumors. However, further studies are required to better understand the role of RNA methylation in human cancers for designing diagnostic and treatment strategies and predicting the prognosis of patients.

The interplay between N6-methyladenosine and precancerous liver disease: molecular functions and mechanisms

N6-methyladenosine(m⁶A) is one of the most abundant modifications of mammalian cellular RNAs. m⁶A regulates various biological functions in epitranscriptomic ways, including RNA stability, decay, splicing, translation and nuclear export. Recent studies have indicated the growing importance of m⁶A modification in precancerous disease, influencing viral replication, immune escape, and carcinogenesis. Here, we review the role of m⁶A modification in HBV/HCV infection, NAFLD and liver fibrosis, and its function in liver disease pathogenesis. Our review will provide a new sight for the innovative treatment strategy for precancerous liver disease.

Crosstalk between Thyroid Carcinoma and Tumor-Correlated Immune Cells in the Tumor Microenvironment

Thyroid cancer (TC) is the most common malignancy in the endocrine system. Although most TC can achieve a desirable prognosis, some refractory thyroid carcinomas, including radioiodine-refractory differentiated thyroid cancer, as well as anaplastic thyroid carcinoma, face a myriad of difficulties in clinical treatment. These types of tumors contribute to the majority of TC deaths due to limited initial therapy, recurrence, and metastasis of the tumor and tumor resistance to current clinically targeted drugs, which ultimately lead to treatment failure. At present, a growing number of studies have demonstrated crosstalk between TC and tumor-associated immune cells, which affects tumor deterioration and metastasis through distinct signal transduction or receptor activation. Current immunotherapy focuses primarily on cutting off the interaction between tumor cells and immune cells. Since the advent of immunotherapy, scholars have discovered targets for TC immunotherapy, which also provides new strategies for TC treatment. This review methodically and intensively summarizes the current understanding and mechanism of the crosstalk between distinct types of TC and immune cells, as well as potential immunotherapy strategies and clinical research results in the area of the tumor immune microenvironment. We aim to explore the current research advances to formulate better individualized treatment strategies for TC patients and to provide clues and references for the study of potential immune checkpoints and the development of immunotherapy technologies.