Gut microbiota-dependent adaptor molecule recruits DNA methyltransferase to the TLR4 gene in colonic epithelial cells to suppress inflammatory reactions

Mechanisms underlying delirium in patients with critical illness

Delirium is an acute, global cognitive disorder syndrome, also known as acute brain syndrome, characterized by disturbance of attention and awareness and fluctuation of symptoms. Its incidence is high among critically ill patients. Once patients develop delirium, it increases the risk of unplanned extubation, prolongs hospital stay, increases the risk of nosocomial infection, post-intensive care syndrome-cognitive impairment, and even death. Therefore, it is of great importance to understand how delirium occurs and to reduce the incidence of delirium in critically ill patients. This paper reviews the potential pathophysiological mechanisms of delirium in critically ill patients, with the aim of better understanding its pathophysiological processes, guiding the formulation of effective prevention and treatment strategies, providing a basis for clinical medication.

Intervention in gut microbiota increases intestinal γ-aminobutyric acid and alleviates anxiety behavior: a possible mechanism via the action on intestinal epithelial cells

The role of the gut microbiota in the gut-brain axis has attracted attention in recent years. Some gut microbiota produces γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter in mammals, in vitro, but the correlation between gut microbiota composition and intestinal GABA concentration, as well as the action of intestinal GABA in vivo, are poorly understood. Herein, we found that the intestinal GABA concentration was increased in mice by the intervention of the gut microbiota with neomycin or Bifidobacterium bifidum TMC3115 (TMC3115). Administration of TMC3115 reduced anxiety without affecting serum levels of serotonin, corticosterone, or GABA. We further found that intestinal epithelial cells expressed GABA receptor subunits and mediated mitogen-activated protein kinase signaling upon GABA stimulation. In addition, administration of TMC3115 induced mitogen-activated protein kinase signaling in colonic epithelial cells but not in small intestinal epithelial cells in mice. These results indicate that GABA produced by the gut microbiota, mainly in the colon, may affect host behavioral characteristics via GABA receptors expressed in intestinal epithelial cells without being transferred to the blood. This study suggests a novel mechanism by which intestinal GABA exerts physiological effects, even in the presence of the blood-brain barrier.

Gut microbiota induced epigenetic modifications in the non-alcoholic fatty liver disease pathogenesis

Non-alcoholic fatty liver disease (NAFLD) represents a growing global health concern that can lead to liver disease and cancer. It is characterized by an excessive accumulation of fat in the liver, unrelated to excessive alcohol consumption. Studies indicate that the gut microbiota-host crosstalk may play a causal role in NAFLD pathogenesis, with epigenetic modification serving as a key mechanism for regulating this interaction. In this review, we explore how the interplay between gut microbiota and the host epigenome impacts the development of NAFLD. Specifically, we discuss how gut microbiota-derived factors, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), can modulate the DNA methylation and histone acetylation of genes associated with NAFLD, subsequently affecting lipid metabolism and immune homeostasis. Although the current literature suggests a link between gut microbiota and NAFLD development, our understanding of the molecular mechanisms and signaling pathways underlying this crosstalk remains limited. Therefore, more comprehensive epigenomic and multi-omic studies, including broader clinical and animal experiments, are needed to further explore the mechanisms linking the gut microbiota to NAFLD-associated genes. These studies are anticipated to improve microbial markers based on epigenetic strategies and provide novel insights into the pathogenesis of NAFLD, ultimately addressing a significant unmet clinical need.

Comprehensive modular analyses of scar subtypes illuminate underlying molecular mechanisms and potential therapeutic targets

Pathological scarring resulting from traumas and wounds, such as hypertrophic scars and keloids, pose significant aesthetic, functional and psychological challenges. This study provides a comprehensive transcriptomic analysis of these conditions, aiming to illuminate underlying molecular mechanisms and potential therapeutic targets. We employed a co-expression and module analysis tool to identify significant gene clusters associated with distinct pathophysiological processes and mechanisms, notably lipid metabolism, sebum production, cellular energy metabolism and skin barrier function. This examination yielded critical insights into several skin conditions including folliculitis, skin fibrosis, fibrosarcoma and congenital ichthyosis. Particular attention was paid to Module Cluster (MCluster) 3, encompassing genes like BLK, TRPV1 and GABRD, all displaying high expression and potential implications in immune modulation. Preliminary immunohistochemistry validation supported these findings, showing elevated expression of these genes in non-fibrotic samples rich in immune activity. The complex interplay of different cell types in scar formation, such as fibroblasts, myofibroblasts, keratinocytes and mast cells, was also explored, revealing promising therapeutic strategies. This study underscores the promise of targeted gene therapy for pathological scars, paving the way for more personalised therapeutic approaches. The results necessitate further research to fully ascertain the roles of these identified genes and pathways in skin disease pathogenesis and potential therapeutics. Nonetheless, our work forms a strong foundation for a new era of personalised medicine for patients suffering from pathological scarring.

The role of the glycome in symbiotic host-microbe interactions

Glycosylation plays a crucial role in many aspects of cell biology, including cellular and organismal integrity, structure-and-function of many glycosylated molecules in the cell, signal transduction, development, cancer, and in a number of diseases. Besides, at the inter-organismal level of interaction, a variety of glycosylated molecules are involved in the host-microbiota recognition and initiation of downstream signalling cascades depending on the outcomes of the glycome-mediated ascertainment. The role of glycosylation in host-microbe interactions is better elaborated within the context of virulence and pathogenicity in bacterial infection processes but the symbiotic host-microbe relationships also involve substantive glycome-mediated interactions. The works in the latter field have been reviewed to a much lesser extent, and the main aim of this mini-review is to compensate for this deficiency and summarise the role of glycomics in host-microbe symbiotic interactions.

RBM14 promotes DNA end resection during homologous recombination repair

DNA double-strand break (DSB) repair by homologous recombination (HR) is crucial for the maintenance of genome stability and integrity. In this study, we aim to identify novel RNA binding proteins (RBPs) involved in HR repair because little is known about RBP function in HR. For this purpose, we carry out pulldown assays using a synthetic ssDNA/dsDNA structure coated with replication protein A (RPA) to mimic resected DNA, a crucial intermediate in HR-mediated DSB repair. Using this approach, we identify RNA-binding motif protein 14 (RBM14) as a potential binding partner. We further show that RBM14 interacts with an essential HR repair factor, CtIP. RBM14 is crucial for CtIP recruitment to DSB sites and for subsequent RPA coating and RAD51 replacement, facilitating efficient HR repair. Moreover, inhibition of RBM14 expression sensitizes cancer cells to X-ray irradiation. Together, our results demonstrate that RBM14 promotes DNA end resection to ensure HR repair and may serve as a potential target for cancer therapy.

DNMT1-mediated DNA methylation in toll-like receptor 4 (TLR4) inactivates NF-κB signal pathway-triggered pyroptotic cell death and cellular inflammation to ameliorate lipopolysaccharides (LPS)-induced osteomyelitis

Toll-like receptor 4 (TLR4) plays a critical role in various human diseases, and was associated with pyroptotic cell death and inflammatory responses. DNA methylation, which has stable and reversible properties, has been reported to alter the expression of target genes, including TLR4. However, the role of methylated TLR4 in osteomyelitis (OM) and the underlying molecular mechanisms remain unclear. RNA sequencing was used to identify differentially expressed genes and associated signaling pathways. RT-qPCR, Western blot, emzyme-linked immunosorbent assay (ELISA), cell counting kit-8 (CCK-8) and LDH assay kit were used to detect mRNA and protein expression of relevant genes, cell viability and the LDH activity, respectively. TLR4 methylation was detected by methylation-specific PCR (MSP) and verified by Chromatin immunoprecipitation (ChIP). Here, we found that DNA methyltransferase-1 (DNMT1)-mediated TLR4 demethylation significantly suppressed lipopolysaccharides (LPS)-induced pyroptosis and inflammatory response by inhibiting the TLR4/nuclear transcription factor-kappa B (NF-κB) axis. First, we confirmed TLR4 as the study target by mRNA transcriptome sequencing analysis, and TLR4 was observably high-expressed in both OM patients and LPS-treated osteoblastic MC3T3-E1. Then, we found that downregulation of DNMT1 blocked TLR4 promoter methylation modification, resulting in upregulation of TLR4. Simultaneously, functional experiments indicated that suppression of TLR4 or overexpression of DNMT1 promoted cell proliferation and inhibited cell pyroptosis and inflammation in LPS-induced MC3T3-E1, while upregulation of TLR4 restored the effects of DNMT1 silencing on OM progression. In addition, TLR4 elevated phosphorylation of IκB-α and NF-κB p65 in the NF-κB signal pathway, and inhibition of TLR4 or the NF-κB inhibitor PDTC reversed the influence of inhibition of DNMT1. In conclusion, our study demonstrated that DNMT1-mediated TLR4 DNA methylation alleviated LPS-induced OM by inhibiting the NF-κB signaling pathway.

Gut microbes influence the development of central nervous system disorders through epigenetic inheritance

Central nervous system (CNS) disorders, such as depression, anxiety, and Alzheimer's disease (AD), affect quality of life of patients and pose significant economic and social burdens worldwide. Due to their obscure and complex pathogeneses, current therapies for these diseases have limited efficacy. Over the past decade, the gut microbiome has been shown to exhibit direct and indirect influences on the structure and function of the CNS, affecting multiple pathological pathways. In addition to the direct interactions between the gut microbiota and CNS, the gut microbiota and their metabolites can regulate epigenetic processes, including DNA methylation, histone modification, and regulation of non-coding RNAs. In this review, we discuss the tripartite relationship among gut microbiota, epigenetic inheritance, and CNS disorders. We suggest that gut microbes and their metabolites influence the pathogenesis of CNS disorders at the epigenetic level, which may inform the development of effective therapeutic strategies for CNS disorders.