Diabetes exacerbated sepsis-induced intestinal injury by promoting M1 macrophage polarization via miR-3061/Snail1 signaling

Macrophage polarization in sepsis: Emerging role and clinical application prospect

Sepsis is a severe, potentially fatal condition defined by organ dysfunction due to excessive inflammation. Its complex pathogenesis and poor therapeutic outcomes pose significant challenges in treatment. Macrophages, with their high heterogeneity and plasticity, play crucial roles in both the innate and adaptive immune systems. They can polarize into M1-like macrophages, which promote pro-inflammatory responses, or M2-like macrophages, which mediate anti-inflammatory responses, positioning them as critical mediators in the immune response during sepsis.Macrophages are the main regulators of inflammatory responses, and their polarization is also regulated by inflammatory signaling pathways. This review highlights recent advances in the inflammatory signaling pathways involved in sepsis, mechanism of macrophage polarization mediated by inflammation-related signaling pathways in sepsis, and the role of signaling pathway mediated macrophage polarization in organ dysfunction involved in sepsis. We also explore the therapeutic potential of targeting macrophage polarization for immunotherapy, offering new perspectives on macrophage-targeted treatments for sepsis.

Research progress of non-coding RNA regulating the role of PANoptosis in diabetes mellitus and its complications

Diabetes is a chronic metabolic disease that is endemic worldwide and is characterized by persistent hyperglycemia accompanied by multiple severe complications, including cardiovascular disease, kidney dysfunction, neuropathy, and retinopathy. The pathogenesis of diabetes mellitus and its complications is multifactorial, involving various molecular and cellular pathways. In recent years, research has indicated that mechanisms of cell death play a significant role in the advancement of diabetes and its complications. PANoptosis is a complex phenomenon caused by three cell death pathways: programmed apoptosis, necroptosis and pyroptosis. The contribution of PANoptosis to diabetes and its complications remains incompletely understood. Non-coding RNA, an important molecule in gene expression regulation, has shown significant regulatory functions in a variety of diseases. This paper reviews the underlying mechanisms of diverse types of non-coding RNAs (including lncRNA, miRNA and circRNA) in regulating PANoptosis and their specific contributions in diabetes, aiming to explore how non-coding RNAs influence PANoptosis and their effects in diabetes.

The role of m6A methylation genes in predicting poor prognosis in sepsis: identifying key biomarkers and therapeutic targets

Sepsis is one of the leading causes of death among seriously ill patients worldwide, affecting more than 30 million people annually and accounting for 1-2% of hospitalizations. By analyzing gene expression omnibus (GEO) data set, our team explored the relationship between m6A methylation gene and poor prognosis of sepsis. The purpose of this present study is to examine new detection markers for patients with poor prognosis, provide theoretical basis for timely intervention and improve the survival rate of patients. First, GSE54514 transcriptome data were extracted from the GEO database 31 patients with sepsis related death and 72 sepsis survivors. Key genes were screened from differentially expressed genes (DEGs), least absolute shrinkage and selection operator (LSAAO) and random forest (RF). And then, METTL3, WTAP and RBM15 were further verified by quantitative reverse transcription PCR (qRT-PCR). The constructed nomogram model showed high accuracy in predicting death. These three genes are mainly involved in chemokine signaling pathway, differentiation of monocytes and T cells, and phagocytosis of immune cells. The analysis showed that a high m6A score subtype is linked to lower immunosuppression and higher survival rates in clinical samples, suggesting better immune responses and outcomes for these patients. Finally, the protective effect of METTL3 in sepsis was demonstrated in mouse sepsis model applied with METTL3 inhibitor, by conducting cell flow cytometry analysis, enzyme-linked immunosorbent assay (ELISA) and hematoxylin-eosin (HE) staining. In conclusion, these findings provide potential biomarkers and targets for early precision diagnosis and treatment.

miR-130a-3p enhances autophagy through the YY1/PI3K/AKT/mTOR signaling pathway to regulate macrophage polarization and alleviate diabetic retinopathy

AIMS/INTRODUCTION

Diabetic retinopathy (DR) is a common complication of diabetes that can lead to poor vision and blindness. This study aimed to explore the mechanism of action of miR-130a-3p in DR progression.

MATERIALS AND METHODS

In this study, we administered a single intraperitoneal injection of 100 mg/kg streptozotocin (STZ) to construct a DR mouse model, and induced a human monocyte cell line (THP-1) to differentiate into M0 macrophages, after which the M0 macrophages were cultured with 30 mM high glucose (HG) as a model of inflammation. The relative gene and protein levels were validated by RT-qPCR and western blotting. Macrophage polarization and retinal damage in the mice were tested using ELISA, MDC staining, immunofluorescence staining, and HE staining.

RESULTS

The results revealed that the expression of miR-130a-3p was low in M1 macrophages, whereas the expression of miR-130a-3p was high in M2 macrophages, and the level of miR-130a-3p was reduced after HG treatment of macrophages. The overexpression of miR-130a-3p attenuated HG- or STZ-induced inflammation, promoted macrophage autophagy, inhibited M1 polarization of macrophages, and attenuated the progression of DR. In addition, YY1 was the downstream target gene of miR-130a-3p, and overexpression of miR-130a-3p inhibited YY1 expression. However, overexpression of YY1 weakened the effect of miR-130a-3p mimic. After further treatment with the PI3K/Akt/mTOR pathway activator 740 Y-P, the effect of YY1 knockdown was weakened, macrophage autophagy was inhibited, and M1 polarization and inflammation were promoted.

CONCLUSION

miR-130a-3p inhibited the activation of the PI3K/Akt/mTOR pathway by downregulating YY1 expression, thus facilitating macrophage autophagy, inhibiting M1 polarization and the inflammatory response of macrophages, and finally attenuating the progression of DR. The results of this study provide theoretical support for the use of miR-130a-3p as a new target for the treatment of DR.

Cardamonin protects against diabetic cardiomyopathy by activating macrophage NRF2 signaling through molecular interaction with KEAP1

Diabetic cardiomyopathy (DCM) contributes to a large proportion of heart failure incidents in the diabetic population, but effective therapeutic approaches are rare. Cardamonin (CAD), a flavonoid found in Alpinia, possesses anti-inflammatory and anti-oxidative activities. Here we report a profound protective effect of CAD on DCM in a mouse model of type 2 diabetes induced by streptozotocin and a high-fat diet, in which gavage with CAD improved hyperglycemia and glucose intolerance and mitigated diabetic cardiac injuries including cardiac dysfunction, hypertrophy, apoptotic cell death and infiltration of inflammatory cells, especially M1 polarized macrophages. To verify whether CAD could protect against cardiomyocyte injury through inhibiting macrophage M1 polarization, M1 polarized macrophages were treated with CAD, followed by washing out and co-culturing with cardiomyocytes, showing that CAD remarkably inhibited macrophage M1 polarization and the following cardiomyocyte injury, along with activation of the nuclear factor erythroid 2-related factor 2 (NRF2) antioxidant signaling pathway. Molecular docking and surface plasmon resonance assays found Kelch-like ECH-associated protein 1 (KEAP1) as the molecular target of CAD. Both CAD and the Kelch domain inhibitor Ki696 promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 (NRF2). This work may provide CAD as a novel NRF2 activator in future interventions for DCM.

METTL3-mediated TIM1 promotes macrophage M1 polarization and inflammation through IGF2BP2-dependent manner

Macrophage polarization and inflammation may play an important role in the development of sepsis. T-cell immunoglobulin mucin 1 (TIM1) has been demonstrated to promote macrophage inflammatory responses. However, whether TIM1 regulates macrophage polarization and inflammation to affect sepsis development remains unclear. Human monocytic leukemia cell line was induced into macrophages, followed by stimulated with LPS and IL-4 to induce M1 polarization and M2 polarization. The expression levels of TIM1, methyltransferase 3 (METTL3), and insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) were examined by qRT-PCR and western blot. IL-6, IL-1β, and TNF-α levels were tested by ELISA. CD86+cell rate was analyzed by flow cytometry. The m6A methylation level of TIM1 was assessed by MeRIP assay. The interaction of between TIM1 and METTL3 or IGF2BP2 was assessed by dual-luciferase reporter assay and RIP assay. TIM1 knockdown repressed LPS-induced macrophage M1 polarization and inflammation. In terms of mechanism, METTL3 promoted TIM1 expression through m6A modification, and this modification could be recognized by IGF2BP2. Besides, knockdown of METTL3/IGF2BP2 suppressed LPS-induced macrophage M1 polarization and inflammation, while this effect could be eliminated by TIM1 overexpression. METTL3/IGF2BP2/TIM1 axis promoted macrophage M1 polarization and inflammation, which might provide potential target for sepsis treatment.

Macrophages in the inflammatory response to endotoxic shock

BACKGROUND

Endotoxic shock, particularly prevalent in intensive care units, represents a significant medical challenge. Endotoxin, upon invading the host, triggers intricate interactions with the innate immune system, particularly macrophages. This activation leads to the production of inflammatory mediators such as tumor necrosis factor-alpha, interleukin-6, and interleukin-1-beta, as well as aberrant activation of the nuclear factor-kappa-B and mitogen-activated protein kinase signaling pathways.

OBJECTIVE

This review delves into the intricate inflammatory cascades underpinning endotoxic shock, with a particular focus on the pivotal role of macrophages. It aims to elucidate the clinical implications of these processes and offer insights into potential therapeutic strategies.

RESULTS

Macrophages, central to immune regulation, manifest in two distinct subsets: M1 (classically activated subtype) macrophages and M2 (alternatively activated subtype) macrophages. The former exhibit an inflammatory phenotype, while the latter adopt an anti-inflammatory role. By modulating the inflammatory response in patients with endotoxic shock, these macrophages play a crucial role in restoring immune balance and facilitating recovery.

CONCLUSION

Macrophages undergo dynamic changes within the immune system, orchestrating essential processes for maintaining tissue homeostasis. A deeper comprehension of the mechanisms governing macrophage-mediated inflammation lays the groundwork for an anti-inflammatory, targeted approach to treating endotoxic shock. This understanding can significantly contribute to the development of more effective therapeutic interventions.

Qi Huang Fang improves intestinal barrier function and intestinal microbes in septic mice through NLRP3 inflammasome-mediated cellular pyroptosis

OBJECTIVE

Sepsis has a high incidence, morbidity, and mortality rate and is a great threat to human safety. Gut health plays an important role in sepsis development. Qi Huang Fang (QHF) contains astragalus, rhubarb, zhishi, and atractylodes. It is used to treat syndromes of obstructive qi and deficiency of righteousness. This study aimed to investigate whether QHF improves intestinal barrier function and microorganisms in mice through NLRP3 inflammatory vesicle-mediated cellular focal death.

METHODS

A mouse model of sepsis was constructed by cecal ligation and puncture (CLP) of specific pathogen-free (SPF)-grade C57BL/6 mice after continuous gavage of low, medium, and high doses of astragalus formula or probiotics for 4 weeks. Twenty-four hours postoperatively, the mechanism of action of QHF in alleviating septic intestinal dysfunction and restoring intestinal microecology, thereby alleviating intestinal injury, was evaluated by pathological observation, immunohistochemistry, western blotting, ELISA, and 16S rDNA high-throughput sequencing.

RESULTS

Different doses of QHF and probiotics ameliorated intestinal injury and reduced colonic apoptosis in mice to varying degrees (P < 0.05). Meanwhile, different doses of QHF and probiotics were able to reduce the serum levels of IL-6, IL-1β, and TNF-α (P < 0.05); down-regulate the protein expression of NLRP3, caspase-1, and caspase-11 (P < 0.05); and up-regulate the protein expression of zonula occluden-1 (ZO-1) and occludin (P < 0.05), which improved the intestinal barrier function in mice. In addition, QHF decreased the relative abundance of harmful bacteria (Firmicutes, Muribaculaceae, Campilobacterota, Helicobacter, and Alistipes) and increased the relative abundance of beneficial bacteria (Bacteroidetes and Actinobacteria) (P < 0.05).

CONCLUSION

QHF improves intestinal barrier function and gut microbiology in mice via NLRP3 inflammasome-mediated cellular pyroptosis.

Macrophage plasticity: signaling pathways, tissue repair, and regeneration

Macrophages are versatile immune cells with remarkable plasticity, enabling them to adapt to diverse tissue microenvironments and perform various functions. Traditionally categorized into classically activated (M1) and alternatively activated (M2) phenotypes, recent advances have revealed a spectrum of macrophage activation states that extend beyond this dichotomy. The complex interplay of signaling pathways, transcriptional regulators, and epigenetic modifications orchestrates macrophage polarization, allowing them to respond to various stimuli dynamically. Here, we provide a comprehensive overview of the signaling cascades governing macrophage plasticity, focusing on the roles of Toll-like receptors, signal transducer and activator of transcription proteins, nuclear receptors, and microRNAs. We also discuss the emerging concepts of macrophage metabolic reprogramming and trained immunity, contributing to their functional adaptability. Macrophage plasticity plays a pivotal role in tissue repair and regeneration, with macrophages coordinating inflammation, angiogenesis, and matrix remodeling to restore tissue homeostasis. By harnessing the potential of macrophage plasticity, novel therapeutic strategies targeting macrophage polarization could be developed for various diseases, including chronic wounds, fibrotic disorders, and inflammatory conditions. Ultimately, a deeper understanding of the molecular mechanisms underpinning macrophage plasticity will pave the way for innovative regenerative medicine and tissue engineering approaches.

CircSOD2: Disruption of intestinal mucosal barrier function in ulcerative colitis by regulating the miR-378g/Snail1 axis

BACKGROUND AND AIM

Circular RNA (circRNA) has been found to mediate ulcerative colitis (UC) progression by regulating intestinal mucosal barrier function. However, the role of circSOD2 in UC process and its underlying molecular mechanism still need to be further elucidated.

METHODS

Lipopolysaccharide (LPS)-induced Caco2 cells were used to mimic UC cell models. CircSOD2, miR-378g, and Snail1 levels were determined by quantitative real-time PCR. Cell viability was detected using MTT assay, and inflammatory cytokine levels were measured using ELISA. The intestinal mucosal barrier function was evaluated by testing transepithelial electrical resistance and fluorescein isothiocyanate (FITC)-dextran permeability. Snail1 and tight junction-related markers (Zo-1 and Claudin2) protein levels were examined using western blot. The interaction between miR-378g and circSOD2 or Snail1 was confirmed by dual-luciferase reporter assay. Dextran sulfate sodium (DSS) was used to induce UC rat models in vivo.

RESULTS

CircSOD2 was overexpressed in UC patients, and its knockdown significantly increased cell viability, transepithelial electrical resistance, and tight junction-related protein expression, while reduced inflammation cytokine levels and the permeability of FITC-dextran in LPS-induced Caco2 cells. In terms of mechanism, circSOD2 sponged miR-378g to positively regulate Snail1 expression. MiR-378g inhibitor reversed the effect of circSOD2 knockdown on intestinal mucosal barrier injury and Snail1 expression in LPS-induced Caco2 cells. In DSS-induced UC rat models, circSOD2 knockdown also could repair the intestinal mucosal barrier injury through regulating miR-378g/Snail1 axis.

CONCLUSION

CircSOD2 could destroy intestinal mucosal barrier function in LPS-induced Caco2 cells and DSS-induced UC rats by miR-378g/Snail1 axis.

BPOZ-2-deficient mice exhibit aggravated inflammation-associated tissue damage after acute dextran sodium sulfate or diethylnitrosamine exposure

An excessive inflammatory response plays an important role in pathological tissue damage associated with pathogen infection and tumorigenesis. Blood POZ-containing gene type 2 (BPOZ-2), an adaptor protein for the E3 ubiquitin ligase scaffold protein CUL3, is a negative regulator of the inflammatory response. In this study, we investigated the pathophysiological functions of BPOZ-2 in dextran sodium sulfate (DSS)-induced colon injury and diethylnitrosamine (DEN)-induced liver damage. Our results indicated that BPOZ-2 deficiency increased IL-1β induction after DSS and DEN treatment. In addition, BPOZ-2-deficient mice were more susceptible to DSS-induced colitis. Notably, BPOZ-2 deficiency aggravated DEN-induced acute liver injury. These results revealed that BPOZ-2 protected against pathological tissue damage with a dysregulated inflammatory response.

The Pivotal Role of Macrophages in the Pathogenesis of Pancreatic Diseases

The pancreas is an organ with both exocrine and endocrine functions, comprising a highly organized and complex tissue microenvironment composed of diverse cellular and non-cellular components. The impairment of microenvironmental homeostasis, mediated by the dysregulation of cell-to-cell crosstalk, can lead to pancreatic diseases such as pancreatitis, diabetes, and pancreatic cancer. Macrophages, key immune effector cells, can dynamically modulate their polarization status between pro-inflammatory (M1) and anti-inflammatory (M2) modes, critically influencing the homeostasis of the pancreatic microenvironment and thus playing a pivotal role in the pathogenesis of the pancreatic disease. This review aims to summarize current findings and provide detailed mechanistic insights into how alterations mediated by macrophage polarization contribute to the pathogenesis of pancreatic disorders. By analyzing current research comprehensively, this article endeavors to deepen our mechanistic understanding of regulatory molecules that affect macrophage polarity and the intricate crosstalk that regulates pancreatic function within the microenvironment, thereby facilitating the development of innovative therapeutic strategies that target perturbations in the pancreatic microenvironment.

Immunotherapy in the context of sepsis-induced immunological dysregulation

Sepsis is a clinical syndrome caused by uncontrollable immune dysregulation triggered by pathogen infection, characterized by high incidence, mortality rates, and disease burden. Current treatments primarily focus on symptomatic relief, lacking specific therapeutic interventions. The core mechanism of sepsis is believed to be an imbalance in the host's immune response, characterized by early excessive inflammation followed by late immune suppression, triggered by pathogen invasion. This suggests that we can develop immunotherapeutic treatment strategies by targeting and modulating the components and immunological functions of the host's innate and adaptive immune systems. Therefore, this paper reviews the mechanisms of immune dysregulation in sepsis and, based on this foundation, discusses the current state of immunotherapy applications in sepsis animal models and clinical trials.

Intestinal Piezo1 aggravates intestinal barrier dysfunction during sepsis by mediating Ca2+ influx

INTRODUCTION

Intestinal barrier dysfunction is a pivotal factor in sepsis progression. The mechanosensitive ion channel Piezo1 is associated with barrier function; however, its role in sepsis-induced intestinal barrier dysfunction remains poorly understood.

METHODS

The application of cecal ligation and puncture (CLP) modeling was performed on both mice of the wild-type (WT) variety and those with Villin-Piezo1flox/flox genetic makeup to assess the barrier function using in vivo FITC-dextran permeability measurements and immunofluorescence microscopy analysis of tight junctions (TJs) and apoptosis levels. In vitro, Caco-2 monolayers were subjected to TNF-α incubation. Moreover, to modulate Piezo1 activation, GsMTx4 was applied to inhibit Piezo1 activation. The barrier function, intracellular calcium levels, and mitochondrial function were monitored using calcium imaging and immunofluorescence techniques.

RESULTS

In the intestinal tissues of CLP-induced septic mice, Piezo1 protein levels were notably elevated compared with those in normal mice. Piezo1 has been implicated in the sepsis-mediated disruption of TJs, apoptosis of intestinal epithelial cells, elevated intestinal mucosal permeability, and systemic inflammation in WT mice, whereas these effects were absent in Villin-Piezo1flox/flox CLP mice. In Caco-2 cells, TNF-α prompted calcium influx, an effect reversed by GsMTx4 treatment. Elevated calcium concentrations are correlated with increased accumulation of reactive oxygen species, diminished mitochondrial membrane potential, and TJ disruption.

CONCLUSIONS

Thus, Piezo1 is a potential contributor to sepsis-induced intestinal barrier dysfunction, influencing apoptosis and TJ modification through calcium influx-mediated mitochondrial dysfunction.

MicroRNA-483-3p Inhibitor Ameliorates Sepsis-Induced Intestinal Injury by Attenuating Cell Apoptosis and Cytotoxicity Via Regulating HIPK2

Sepsis is a life-threatening syndrome that can result in multi-organ dysfunction. MicroRNA (miR)-483-3p was previously demonstrated to be upregulated in sepsis patients; however, its specific functions in sepsis-triggered intestinal injury remain unclarified. Human intestinal epithelial NCM460 cell line was stimulated with lipopolysaccharide (LPS) to mimic sepsis-induced intestinal injury in vitro. Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining was utilized for examining cell apoptosis. Western blotting and real time quantitative polymerase chain reaction (RT-qPCR) were used for detecting molecular protein and RNA levels. LPS-induced cytotoxicity was determined by measuring concentrations of lactate dehydrogenase (LDH), diamine oxidase (DAO) and fatty acid binding protein 2 (FABP2). Luciferase reporter assay was utilized for verifying the interaction between miR-483-3p and homeodomain interacting protein kinase 2 (HIPK2). Inhibiting miR-483-3p alleviates LPS-triggered NCM460 cell apoptosis and cytotoxicity. miR-483-3p targeted HIPK2 in LPS-stimulated NCM460 cells. Knockdown of HIPK2 reversed the above effects mediated by miR-483-3p inhibitor. Inhibiting miR-483-3p ameliorates LPS-triggered apoptosis and cytotoxicity by targeting HIPK2.

Long-term administration of probiotics prevents gastrointestinal mucosal barrier dysfunction in septic mice partly by upregulating the 5-HT degradation pathway

Sepsis can impair gastrointestinal (GI) barrier integrity. Oral probiotics (PT) can maintain the balance of GI microflora and improve GI function. 5-Hydroxytryptamine (5-HT) is a key promoter of GI injury caused by sepsis. However, the mechanism by which PT attenuates sepsis by regulating 5-HT is not fully understood. In this study, C57BL6 mice were intragastric administrated with normal saline (NC) or PT once a day for 4 weeks before cecal ligation and puncture (CLP). Compared with NC-CLP mice, PT-CLP mice had lower clinical score, higher body temperature. The survival rate of PT-CLP mice was significantly improved. The levels of inflammatory cytokines and 5-HT were obviously decreased in PT-CLP mice, and GI peristalsis and barrier function were enhanced. Moreover, sepsis downregulated the expression of tight junction proteins, while PT pretreatment could maintain them at the level of sham operation group. Furthermore, PT pretreatment increased the expression of serotonin transporter and monoamine oxidase A. PT administration could inhibit NF-κB activity, and activate ERK activity. In conclusion, long-term supplementation of PT before CLP can prevent sepsis-induced GI mucosal barrier dysfunction in mice, which may be partially mediated by upregulating the 5-HT degradation pathway via activating ERK signaling.

NAD+ Precursors and Intestinal Inflammation: Therapeutic Insights Involving Gut Microbiota

The oxidized form of nicotinamide adenine dinucleotide (NAD+) is a critical metabolite for living cells. NAD+ may act either as a cofactor for many cellular reactions as well as a coenzyme for different NAD+-consuming enzymes involved in the physiological homeostasis of different organs and systems. In mammals, NAD+ is synthesized from either tryptophan or other vitamin B3 intermediates that act as NAD+ precursors. Recent research suggests that NAD+ precursors play a crucial role in maintaining the integrity of the gut barrier. Indeed, its deficiency has been associated with enhanced gut inflammation and leakage, and dysbiosis. Conversely, NAD+-increasing therapies may confer protection against intestinal inflammation in experimental conditions and human patients, with accumulating evidence indicating that such favorable effects could be, at least in part, mediated by concomitant changes in the composition of intestinal microbiota. However, the mechanisms by which NAD+-based treatments affect the microbiota are still poorly understood. In this context, we have focused specifically on the impact of NAD+ deficiency on intestinal inflammation and dysbiosis in animal and human models. We have further explored the relationship between NAD+ and improved host intestinal metabolism and immunity and the composition of microbiota in vivo. Overall, this comprehensive review aims to provide a new perspective on the effect of NAD+-increasing strategies on host intestinal physiology.