m6A mRNA methylation controls T cell homeostasis by targeting the IL-7/STAT5/SOCS pathways.

N6-methyladenosine (m6A) is the most common and abundant messenger RNA modification, modulated by 'writers', 'erasers' and 'readers' of this mark. In vitro data have shown that m6A influences all fundamental aspects of mRNA metabolism, mainly mRNA stability, to determine stem cell fates. However, its in vivo physiological function in mammals and adult mammalian cells is still unknown. Here we show that the deletion of m6A 'writer' protein METTL3 in mouse T cells disrupts T cell homeostasis and differentiation. In a lymphopaenic mouse adoptive transfer model, naive Mettl3-deficient T cells failed to undergo homeostatic expansion and remained in the naive state for up to 12 weeks, thereby preventing colitis. Consistent with these observations, the mRNAs of SOCS family genes encoding the STAT signalling inhibitory proteins SOCS1, SOCS3 and CISH were marked by m6A, exhibited slower mRNA decay and showed increased mRNAs and levels of protein expression in Mettl3-deficient naive T cells. This increased SOCS family activity consequently inhibited IL-7-mediated STAT5 activation and T cell homeostatic proliferation and differentiation. We also found that m6A has important roles for inducible degradation of Socs mRNAs in response to IL-7 signalling in order to reprogram naive T cells for proliferation and differentiation. Our study elucidates for the first time, to our knowledge, the in vivo biological role of m6A modification in T-cell-mediated pathogenesis and reveals a novel mechanism of T cell homeostasis and signal-dependent induction of mRNA degradation.

[RNA m 6A Modification and Its Roles in Immune Function Regulation].

N 6-methyladenosine (m 6A) is the most prevalent post-transcriptional RNA modification in eukaryotic cells. m 6A methyltransferase complexes and demethylases are involved in the dynamic and reversible regulation of m 6A modification, while m 6A binding proteins could specifically identify m 6A modification and regulate RNA metabolism, including splicing, translocation, stability, and translation. m 6A is found to play a vital role in all the fundamental biological processes, including the regulation of the immune system, from normal development to diseases. The normal development and functioning of the immune system rely on the precise regulation of the relevant gene expression, and m 6A modification is crucial to the regulation. Herein, we reviewed the concept, the functions, and the mechanism of m 6A modification, concentrating on its role in immune system function modulation. Furthermore, we highlighted present obstacles and future research directions in the field, intending to provide a theoretical foundation and reference for future study on how m 6A modification is involved in immune regulation.

Regulatory T cells as a therapeutic target in acute myocardial infarction.

Acute myocardial infarction (AMI), mainly triggered by vascular occlusion or thrombosis, is the most prevalent cause of morbidity and mortality among all cardiovascular diseases. The devastating consequences of AMI are further aggravated by the intricate cellular processes involved in inflammation. In the past two decades, many studies have reported that regulatory T cells (Tregs), as the main immunoregulatory cells, play a crucial role in AMI progression. This review offers a comprehensive insight into the intricate relationship between Tregs and AMI development. Moreover, it explores emerging therapeutic strategies that focus on Tregs and their exosomes. Furthermore, we underscore the importance of employing noninvasive in vivo imaging techniques to advance the clinical applications of Tregs-based treatments in AMI. Although further research is essential to fully elucidate the molecular mechanisms underlying the effects of Tregs, therapies tailored to these cells hold immense potential for the treatment of patients with AMI.

Early detection of cardiac fibrosis in diabetic mice by targeting myocardiopathy and matrix metalloproteinase 2.

Early detection of myocardial fibrosis in diabetic cardiomyopathy (DCM) has significant clinical implications for diabetes management. In this study, we identified matrix metalloproteinase 2 (MMP2) as a potential biomarker for early fibrosis detection. Based on this finding, we designed a dual-targeting nanoparticle CHP-SPIO-ab MMP2 to specifically target myocardiopathy and MMP2, enabling sensitive fibrosis detection using magnetic resonance imaging (MRI). Our results demonstrate that collagen hyperplasia (early fiber formation) begins to develop in diabetic mice at 12 weeks old, with observable fibrosis occurring at 16 weeks old. Additionally, MMP2 expression significantly up-regulates around collagen starting from 12 weeks of age. T2 MRI analysis revealed significant T2% enhancement in the hearts of 12-week-old diabetic mice following administration of the CHP-SPIO-ab MMP2 probe, indicating noninvasive detection of fiber formation. Furthermore, after fibrosis treatment, a reduction in T2% signal was observed in the hearts of 16-week-old diabetic mice. These findings were supported by Sirius red and Prussian blue staining techniques. Overall, our study presents a promising strategy for early identification of myocardial fibrosis. STATEMENT OF SIGNIFICANCE: Myocardial damage typically exhibits irreversibility, underscoring the paramount importance of early fibrosis diagnosis. However, the clinical used T1 mapping for fibrosis detection still exhibits limitations in terms of sensitivity. Therefore, it is imperative to develop highly sensitive strategies for early cardiac fibrosis detection. Here, we investigated the development of myocardial fibrosis in diabetic mice, and designed a highly sensitive probe that specifically targets cardiomyopathy and high expression of MMP2 for the early diagnosis of fibrosis. The probe enables non-invasive detection of abnormalities through MRI imaging as soon as fiber deposition appear, which can be detected earlier than T1 mapping. This advancement holds great potential for clinical diagnosis of myocardial fibrosis using cardiac magnetic resonance.

Unraveling Estrogen and PCSK9's Roles in Lipid Metabolism Disorders among Ovariectomized Mice.

We explore the interaction between estrogen and PCSK9 and their collective impact on lipid metabolism, especially concerning the regulation of low-density lipoprotein receptor levels. Utilizing both animal and cellular models, including ovariectomized mice and HepG2 cell lines, we demonstrate that estrogen deficiency leads to a disruption in lipid metabolism, characterized by elevated levels of total cholesterol and LDL-C. The study commences with mice undergoing ovariectomy, followed by a diet regimen comprising either high-fat diet or normal feed for a four-week duration. Key assessments include analyzing lipid metabolism, measuring PCSK9 levels in the bloodstream, and evaluating hepatic low-density lipoprotein receptor expression. We will also conduct correlation analyses to understand the relationship between PCSK9 and various lipid profiles. Further, a subset of ovariectomized mice on high-fat diet will undergo treatment with either estrogen or PCSK9 inhibitor for two weeks, with a subsequent re-evaluation of the earlier mentioned parameters. Our findings reveal that estrogen inhibits PCSK9-mediated degradation of low-density lipoprotein receptor, a process crucial for maintaining lipid homeostasis. Through a series of experiments, including immunohistochemistry and western blot analysis, we establish that PCSK9 is involved in lipid metabolism disorders caused by estrogen deficiency and that estrogen regulates PCSK9 and low-density lipoprotein receptor at post-transcriptional level. The study provides a mechanism for the involvement of PCSK9 in elucidating the disorders of lipid metabolism caused by estrogen deficiency due to perimenopause and ovarian decline.

A lncRNA from an inflammatory bowel disease risk locus maintains intestinal host-commensal homeostasis.

Inflammatory bowel diseases (IBD) are known to have complex, genetically influenced etiologies, involving dysfunctional interactions between the intestinal immune system and the microbiome. Here, we characterized how the RNA transcript from an IBD-associated long non-coding RNA locus ("CARINH-Colitis Associated IRF1 antisense Regulator of Intestinal Homeostasis") protects against IBD. We show that CARINH and its neighboring gene coding for the transcription factor IRF1 together form a feedforward loop in host myeloid cells. The loop activation is sustained by microbial factors, and functions to maintain the intestinal host-commensal homeostasis via the induction of the anti-inflammatory factor IL-18BP and anti-microbial factors called guanylate-binding proteins (GBPs). Extending these mechanistic insights back to humans, we demonstrate that the function of the CARINH/IRF1 loop is conserved between mice and humans. Genetically, the T allele of rs2188962, the most probable causal variant of IBD within the CARINH locus from the human genetics study, impairs the inducible expression of the CARINH/IRF1 loop and thus increases genetic predisposition to IBD. Our study thus illustrates how an IBD-associated lncRNA maintains intestinal homeostasis and protects the host against colitis.

m6A modifications regulate intestinal immunity and rotavirus infection.

N6-methyladenosine (m6A) is an abundant mRNA modification and affects many biological processes. However, how m6A levels are regulated during physiological or pathological processes such as virus infections, and the in vivo function of m6A in the intestinal immune defense against virus infections are largely unknown. Here, we uncover a novel antiviral function of m6A modification during rotavirus (RV) infection in small bowel intestinal epithelial cells (IECs). We found that rotavirus infection induced global m6A modifications on mRNA transcripts by down-regulating the m6a eraser ALKBH5. Mice lacking the m6A writer enzymes METTL3 in IECs (Mettl3ΔIEC) were resistant to RV infection and showed increased expression of interferons (IFNs) and IFN-stimulated genes (ISGs). Using RNA-sequencing and m6A RNA immuno-precipitation (RIP)-sequencing, we identified IRF7, a master regulator of IFN responses, as one of the primary m6A targets during virus infection. In the absence of METTL3, IECs showed increased Irf7 mRNA stability and enhanced type I and III IFN expression. Deficiency in IRF7 attenuated the elevated expression of IFNs and ISGs and restored susceptibility to RV infection in Mettl3ΔIEC mice. Moreover, the global m6A modification on mRNA transcripts declined with age in mice, with a significant drop from 2 weeks to 3 weeks post birth, which likely has broad implications for the development of intestinal immune system against enteric viruses early in life. Collectively, we demonstrated a novel host m6A-IRF7-IFN antiviral signaling cascade that restricts rotavirus infection in vivo.

Novel Insights Into the Potential Mechanisms of N6-Methyladenosine RNA Modification on Sepsis-Induced Cardiovascular Dysfunction: An Update Summary on Direct and Indirect Evidences.

Sepsis is a life-threatening organ dysfunction caused by a host's dysfunctional response to infection. As is known to all, septic heart disease occurs because pathogens invading the blood stimulate the activation of endothelial cells, causing a large number of white blood cells to accumulate and trigger an immune response. However, in severe sepsis, the hematopoietic system is inhibited, and there will also be a decline in white blood cells, at which time the autoimmune system will also be suppressed. During the immune response, a large number of inflammatory factors are released into cells to participate in the inflammatory process, which ultimately damages cardiac myocytes and leads to impaired cardiac function. N6-methyladenosine (m6A) is a common RNA modification in mRNA and non-coding RNA that affects RNA splicing, translation, stability, and epigenetic effects of some non-coding RNAs. A large number of emerging evidences demonstrated m6A modification had been involved in multiple biological processes, especially for sepsis and immune disorders. Unfortunately, there are limited results provided to analyze the association between m6A modification and sepsis-induced cardiovascular dysfunction (SICD). In this review, we firstly summarized current evidences on how m6A mediates the pathophysiological process in cardiac development and cardiomyopathy to emphasize the importance of RNA methylation in maintaining heart biogenesis and homeostasis. Then, we clarified the participants of m6A modification in extended inflammatory responses and immune system activation, which are the dominant and initial changes secondary to sepsis attack. After that, we deeply analyzed the top causes of SICD and identified the activation of inflammatory cytokines, endothelial cell dysfunction, and mitochondrial failure. Thus, the highlight of this review is that we systematically collected all the related potential mechanisms between m6A modification and SICD causes. Although there is lack of direct evidences on SICD, indirect evidences had been demonstrated case by case on every particular molecular mechanism and signal transduction, which require further explorations into the potential links among the listed mechanisms. This provides novel insights into the understanding of SICD.

The Role of Helper T Cells in Psoriasis.

Psoriasis is a complex, chronic relapsing and inflammatory skin disorder with a prevalence of approximately 2% in the general population worldwide. Psoriasis can be triggered by infections, physical injury and certain drugs. The most common type of psoriasis is psoriasis vulgaris, which primarily features dry, well-demarcated, raised red lesions with adherent silvery scales on the skin and joints. Over the past few decades, scientific research has helped us reveal that innate and adaptive immune cells contribute to the chronic inflammatory pathological process of psoriasis. In particular, dysfunctional helper T cells (Th1, Th17, Th22, and Treg cells) are indispensable factors in psoriasis development. When stimulated by certain triggers, antigen-presenting cells (APCs) can release pro-inflammatory factors (IL-23, IFN-α and IL-12), which further activate naive T cells and polarize them into distinct helper T cell subsets that produce numerous cytokines, such as TNF, IFN-γ, IL-17 and IL-22, which act on keratinocytes to amplify psoriatic inflammation. In this review, we describe the function of helper T cells in psoriasis and summarize currently targeted anti-psoriatic therapies.

Pooled CRISPR screening identifies m6A as a positive regulator of macrophage activation.

m6A RNA modification is implicated in multiple cellular responses. However, its function in the innate immune cells is poorly understood. Here, we identified major m6A "writers" as the top candidate genes regulating macrophage activation by LPS in an RNA binding protein focused CRISPR screening. We have confirmed that Mettl3-deficient macrophages exhibited reduced TNF-α production upon LPS stimulation in vitro. Consistently, Mettl3 flox/flox;Lyzm-Cre mice displayed increased susceptibility to bacterial infection and showed faster tumor growth. Mechanistically, the transcripts of the Irakm gene encoding a negative regulator of TLR4 signaling were highly decorated by m6A modification. METTL3 deficiency led to the loss of m6A modification on Irakm mRNA and slowed down its degradation, resulting in a higher level of IRAKM, which ultimately suppressed TLR signaling-mediated macrophage activation. Our findings demonstrate a previously unknown role for METTL3-mediated m6A modification in innate immune responses and implicate the m6A machinery as a potential cancer immunotherapy target.

RNA m6A modification and its function in diseases.

N6-methyladenosine (m6A) is the most common post-transcriptional RNA modification throughout the transcriptome, affecting fundamental aspects of RNA metabolism. m6A modification could be installed by m6A "writers" composed of core catalytic components (METTL3/METTL14/WTAP) and newly defined regulators and removed by m6A "erasers" (FTO and ALKBH5). The function of m6A is executed by m6A "readers" that bind to m6A directly (YTH domain-containing proteins, eIF3 and IGF2BPs) or indirectly (HNRNPA2B1). In the past few years, advances in m6A modulators ("writers," "erasers," and "readers") have remarkably renewed our understanding of the function and regulation of m6A in different cells under normal or disease conditions. However, the mechanism and the regulatory network of m6A are still largely unknown. Moreover, investigations of the m6A physiological roles in human diseases are limited. In this review, we summarize the recent advances in m6A research and highlight the functional relevance and importance of m6A modification in in vitro cell lines, in physiological contexts, and in cancers.

Long-term consumption of caffeine-free high sucrose cola beverages aggravates the pathogenesis of EAE in mice.

Epidemiological data provide strong evidence of dramatically increasing incidences of many autoimmune diseases in the past few decades, mainly in western and westernized countries. Recent studies clearly revealed that 'Western diet' increases the risk of autoimmune diseases at least partially via disrupting intestinal tight junctions and altering the construction and metabolites of microbiota. However, the role of high sucrose cola beverages (HSCBs), which are one of the main sources of added sugar in the western diet, is barely known. Recently, a population study showed that regular consumption of sugar-sweetened beverages is associated with increased risk of seropositive rheumatoid arthritis in women, which provokes interest in the genuine effects of these beverages on the pathogenesis of autoimmune diseases and the underlying mechanisms. Here we showed that long-term consumption of caffeine-free HSCBs aggravated the pathogenesis of experimental autoimmune encephalomyelitis in mice in a microbiota-dependent manner. Further investigation revealed that HSCBs altered community structure of microbiota and increased Th17 cells. High sucrose consumption had similar detrimental effects while caffeine contamination limited the infiltrated pathogenic immune cells and counteracted these effects. These results uncovered a deleterious role of decaffeinated HSCBs in aggravating the pathogenesis of experimental autoimmune encephalomyelitis in mice.

mTOR inhibition potentiates cytotoxicity of Vγ4 γδ T cells via up-regulating NKG2D and TNF-α.

γδ T cells play a critical role in early anti-tumor immunity and perform cytotoxicity via NKG2D for recognition and multiple cytotoxic factors for tumor killing. Recent studies have demonstrated pivotal roles of mTOR-mediated metabolism in the maturation, differentiation, and effector function of diverse immune cells, including DCs, NK cells, CD4+ T cell subsets, and CD8+ T cells, but the role of mTOR signaling in γδ T cells is barely known. Here, we showed that suppressing mTOR signaling in in vitro-expanded Vγ4 γδ T cells via the mechanistic inhibitor rapamycin enhanced their cytotoxicity against multiple tumor cell lines, and these cells performed better tumor-suppressing effects upon adoptive therapy. Further investigation revealed that elevated cytotoxicity was a result of up-regulation of NKG2D and TNF-α. Moreover, rapamycin treatment significantly decreased the expression of CISH and increased pSTAT5. The inhibition of STAT5 pathways via siRNA interference or a specific inhibitor eliminated the up-regulation of NKG2D and TNF-α in rapamycin-treated Vγ4 γδ T cells. These results uncovered an important role of mTOR signaling in the cytotoxic effector function of γδ T cells and provided a potential strategy to improve γδ T cell-based cancer immunotherapy.

The DNA-sensing AIM2 inflammasome controls radiation-induced cell death and tissue injury.

Acute exposure to ionizing radiation induces massive cell death and severe damage to tissues containing actively proliferating cells, including bone marrow and the gastrointestinal tract. However, the cellular and molecular mechanisms underlying this pathology remain controversial. Here, we show that mice deficient in the double-stranded DNA sensor AIM2 are protected from both subtotal body irradiation-induced gastrointestinal syndrome and total body irradiation-induced hematopoietic failure. AIM2 mediates the caspase-1-dependent death of intestinal epithelial cells and bone marrow cells in response to double-strand DNA breaks caused by ionizing radiation and chemotherapeutic agents. Mechanistically, we found that AIM2 senses radiation-induced DNA damage in the nucleus to mediate inflammasome activation and cell death. Our results suggest that AIM2 may be a new therapeutic target for ionizing radiation exposure.

[Rapid detection of Listeria monocytogenes by immunomagnetic separation combined with selective medium].

Listeria monocytogenes is a pathogenic bacterium, therefore, it is essential for food safety monitoring to establish a rapid and specific detecting method. In this study, immunomagnetic beads and selective medium were combined to detect Listeria monocytogenes at different concentrations (10(1)-10(5) CFU/mL). Other three types of Listeria spp., Staphylococcus aureus and Vibrio parahaemolyticus were also detected to conduct the cross-reaction analysis. Meanwhile, contaminated milk samples were prepared to explore the limit of detection of immunomagnetic beads combining with selective medium. Results showed that Listeria monocytogenes with the concentration of 10(3) CFU/mL and above was successfully detected. Milk samples were detected within 6 hours, with a detection limit of 0.7 CFU/mL. The method developed is capable of detecting milk samples within 30 h, which is 38 h faster compared with national standard method with the same sensitivity.