The NLR family of innate immune and cell death sensors

Costunolide: Targeting endothelial cell PANoptosis to mitigate lung injury in acute pancreatitis mice

BACKGROUND

Acute pancreatitis (AP) presents several critical risks, among which acute lung injury (ALI) is one of the most severe complications. Previous research has highlighted the anti-inflammatory properties of costunolide (COS); however, its potential to prevent AP-associated ALI remains unexplored. Here, we hypothesize that COS can mitigate AP-induced lung injury by reducing endothelial cell PANoptosis-a form of programmed cell death.

PURPOSE

The work aimed to examine the therapeutic effect and mechanism of COS on lung injury in AP mice, with particular emphasis on its impact on endothelial cell PANoptosis.

STUDY DESIGN

The AP mouse model was created with partial pancreatic duct ligation followed by a single injection of caerulein, and the therapeutic benefits of varying dosages of COS on these AP mice were evaluated. Dexamethasone served as the positive control. The endothelial cell damage caused by CIRP served as an in vitro model to assess the impact of varying doses of COS on PANoptosis.

METHODS

Initially, the toxicological impact of varying doses of COS on the main organs of healthy mice was assessed, subsequently examining the inhibitory effects of COS on pancreatic and pulmonary damage, inflammatory response, and lung tissue PANoptosis in AP mice. Transcriptomic sequencing of pancreatic and pulmonary tissue was used to identify critical targets for COS intervention in AP. To investigate if CIRP activation can elicit PANoptosis and the inhibitory effects of COS in human umbilical vein endothelial cells, the regulatory impact of COS on ALDH2 was assessed via gene knockdown, western blot, and ELISA.

RESULTS

COS demonstrated substantial anti-inflammatory and lung-protective effects in AP mice. Notably, COS significantly downregulated the expression of PANoptosis markers in the lung tissue of AP mice. Cold-induced RNA-binding proteins (a damage-associated molecular pattern that increases during AP) cause increased production of PANoptosis markers in human umbilical vein endothelial cells, while COS exerted a dose-dependent inhibitory effect on these markers. Single-cell RNA sequencing and bulk transcriptomic analysis, Mendelian randomization, molecular docking and molecular dynamics simulation identified alcohol dehydrogenase 2 (ALDH2) as a possible target for COS intervention in AP-related ALI. Subsequent lentiviral transfection, ELISA,‌ and western blot assays confirmed that COS's PANoptosis-inhibitory effect in endothelial cells is partially dependent on ALDH2 activity and expression.

CONCLUSION

Our findings indicate that COS, a novel ALDH2 activator, may treat AP-associated ALI by inhibiting ZBP1-mediated PANoptosis in endothelial cells, thereby establishing a theoretical basis for the clinical use of COS and identifying an entirely novel target for AP-associated ALI treatment.

Distinct roles of the circMKNK2/miR-15a Axis in regulating chicken skeletal muscle development and glucose metabolism

Circular RNAs (circRNAs) have emerged as critical regulators of biological processes, but their roles in avian muscle development remain less explored. Here we characterize circMKNK2, a novel circRNA derived from the MKNK2 gene, which is highly expressed in slow-growing Silky chickens compared to fast-growing broilers. Functional studies demonstrate that circMKNK2 acts as a sponge for miR-15a, with overexpression inhibiting myoblast proliferation, differentiation, apoptosis, and glucose metabolism, while miR-15a knockdown produces similar effects except for enhanced glucose uptake. RNA-seq analysis identified 2189 differentially expressed genes regulated by circMKNK2 in chicken primary myoblasts, including key targets of the circMKNK2/miR-15a axis such as PIK3R1 (a core node regulating PI3K-Akt signaling), BHLHE41, KANK1, and ARHGAP20. Pathway analysis revealed modulation of myogenesis through Calcium signaling pathway, ECM-receptor interaction, Neuroactive ligand-receptor interaction and immune-related pathways (Toll-like receptor, cytokine-cytokine receptor interactions). Further analysis highlighted the circMKNK2/miR-15a axis's role in suppressing myogenesis through transcriptional regulation of key factors (e.g., SOX7, MAF) and metabolic reprogramming. Unlike pro-myogenic circRNAs, circMKNK2 uniquely inhibited muscle development and glucose metabolism, suggesting its involvement in breed-specific phenotypic differences. This study provides insights into circRNA-mediated regulation of muscle biology and offers potential targets for improving poultry production through genetic and metabolic modulation.

NLRs in tumor chemotherapy resistance: A double-edged sword

Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are a numerous family of cytoplasmic proteins. Members of this family not only function as innate immune sensors, but also serve as transcriptional regulators of major histocompatibility complex class II (MHC II) and major histocompatibility complex class I (MHC I) genes to activate adaptive immunity. Furthermore, NLRs are involved in mediating various signaling pathways, including the inflammasome. To date, extensive research has been conducted on the contradictory roles and mechanisms of NLRs in the occurrence, development, invasion, and metastasis of tumors within the tumor microenvironment (TME). The double-edged sword effect (either positive or negative role) of NLRs in the treatment of malignant tumors has attracted increasing attention in recent years, making these a promising bidirectional therapeutic target for such tumors. Rational utilization of the double-edged sword nature of NLRs can provide a feasible solution for improving the efficacy of malignant tumor treatment and overcoming chemotherapy resistance. This article provides a systematic review of the influence of the NLR family on chemosensitivity in different malignant tumors and the regulatory mechanisms of their upstream and downstream signaling pathways. In doing do, we aim to elucidate the dual role of NLRs in promoting and combating tumor chemotherapy resistance, and elucidate their application value in tumor chemotherapy resistance.

PANoptosis-related gene biomarkers in aortic dissection

INTRODUCTION

Programmed cell death of vascular smooth muscle cells (VSMCs) is critical in the pathogenesis of aortic dissection (AD), yet the role of PANoptosis-comprising pyroptosis, apoptosis, and necroptosis-remains unclear.

METHODS

We utilized the GSE213740 single-cell sequencing dataset to assess PANoptosis levels in VSMCs. Datasets GSE153434 and GSE147026 were employed to identify differentially expressed genes (DEGs) and perform weighted gene co-expression network analysis. PANoptosis gene sets were sourced from the GSEA website, with GSE52093 serving as the validation cohort. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Protein-Protein Interaction analyses were conducted, along with assessments of upstream regulators and immune cell infiltration. Validation was performed on aortic tissues from AD patients and mouse models.

RESULTS

The single-cell dataset revealed an increased PANoptosis score in VSMCs in AD. Nineteen PANoptosis-related DEGs (PANDEGs) were identified, contributing to VSMC differentiation, DNA damage response, and apoptosis. KEGG analysis highlighted the P53 and TGF-β pathways, with PANDEGs positively correlating with immune cell infiltration. Key PANDEGs GADD45B, CDKN1A, and SOD2 were validated, showing co-expression with α-SMA.

CONCLUSION

The increased PANoptosis score in VSMCs suggests that GADD45B, CDKN1A, and SOD2 play crucial roles in AD.

HCK regulates NLRP12-mediated PANoptosis

NOD-like receptors (NLRs) are a highly conserved family of cytosolic pattern recognition receptors that drive innate immune responses against pathogens, pathogen-associated molecular patterns, damage-associated molecular patterns, and homeostatic disruptions. Within the NLR family, NLRP12 was recently identified as a key regulator of PANoptosis, which is an innate immune, lytic cell death pathway initiated by innate immune sensors and driven by caspases and RIPKs through PANoptosome complexes. While NLRP12 activation is critical for maintaining homeostasis, aberrant activation has been implicated in a broad range of disorders, including cancers and metabolic, infectious, autoinflammatory, and hemolytic diseases. However, the molecular mechanisms of NLRP12 activation remain poorly understood. Here, we identified hematopoietic cell kinase (HCK) as a regulator of NLRP12-mediated PANoptosis. HCK expression was significantly upregulated in response to NLRP12-PANoptosome triggers. Moreover, Hck knockdown inhibited NLRP12-mediated PANoptosis. Computational analyses identified residues in the putative interaction interface between NLRP12 and HCK, suggesting that HCK likely binds NLRP12 in the region between its NACHT domain and pyrin domain (PYD); removal of the NLRP12 PYD abrogated this interaction in vitro. Overall, our work identifies HCK as a regulator of NLRP12-mediated PANoptosis, suggesting that it may serve as a potential therapeutic target for mitigating inflammation and pathology.

The immune system in cardiovascular diseases: from basic mechanisms to therapeutic implications

Immune system plays a crucial role in the physiological and pathological regulation of the cardiovascular system. The exploration history and milestones of immune system in cardiovascular diseases (CVDs) have evolved from the initial discovery of chronic inflammation in atherosclerosis to large-scale clinical studies confirming the importance of anti-inflammatory therapy in treating CVDs. This progress has been facilitated by advancements in various technological approaches, including multi-omics analysis (single-cell sequencing, spatial transcriptome et al.) and significant improvements in immunotherapy techniques such as chimeric antigen receptor (CAR)-T cell therapy. Both innate and adaptive immunity holds a pivotal role in CVDs, involving Toll-like receptor (TLR) signaling pathway, nucleotide-binding oligomerization domain-containing proteins 1 and 2 (NOD1/2) signaling pathway, inflammasome signaling pathway, RNA and DNA sensing signaling pathway, as well as antibody-mediated and complement-dependent systems. Meanwhile, immune responses are simultaneously regulated by multi-level regulations in CVDs, including epigenetics (DNA, RNA, protein) and other key signaling pathways in CVDs, interactions among immune cells, and interactions between immune and cardiac or vascular cells. Remarkably, based on the progress in basic research on immune responses in the cardiovascular system, significant advancements have also been made in pre-clinical and clinical studies of immunotherapy. This review provides an overview of the role of immune system in the cardiovascular system, providing in-depth insights into the physiological and pathological regulation of immune responses in various CVDs, highlighting the impact of multi-level regulation of immune responses in CVDs. Finally, we also discuss pre-clinical and clinical strategies targeting the immune system and translational implications in CVDs.

PANoptosis as a Two-Edged Sword in Colorectal Cancer: A Pathogenic Mechanism and Therapeutic Opportunity

The examination of PANoptosis in colorectal cancer is particularly important, as many tumor cells can evade apoptotic cell death while continuing to proliferate through inflammatory mediators and creating an immunosuppressive environment. The PANoptosome functions as a regulatory complex that unites proteins governing pyroptotic, apoptotic, and necroptotic pathways, rather than allowing distinct death pathways to compete. The expression and functional status of key molecules within the PANoptosome, such as ZBP1, RIPK1, RIPK3, CASP8, and ASC, may influence tumor viability and immune detection. The tumorigenic impact of PANoptosis is complex and predominantly manifests through chronic inflammation, immune response modulation, and changes in the tumor microenvironment. PANoptosis also aids in the defense against colon cancer by directly eradicating tumor cells and modifying the cellular environment. The expression profile of PANoptosis components may possess prognostic and predictive significance. The therapeutic ramifications of PANoptosis in colorectal cancer are now being investigated through many avenues. It provides an opportunity to develop targeted therapeutic techniques. In contrast, it may also be pertinent in conjunction with immunotherapy, as PANoptosis signifies an immunogenic type of cell death and may consequently enhance the anti-tumor immune response. A thorough comprehension of how these parameters influence PANoptosis is crucial for practical implementation.

Chronic sleep deprivation promotes experimental autoimmune uveitis through STAT1 phosphorylation, ISG15 expression and enhanced pathogenicity of macrophages

Chronic sleep deprivation (CSD) is increasingly common in modern society and is linked to various diseases, including autoimmune conditions like experimental autoimmune uveitis (EAU), a severe ocular inflammation. The pathogenesis of EAU remains unclear, but poor sleep quality has been shown to exacerbate inflammation through immune modulation. To explore this relationship, we conducted a clinical study at the Ophthalmology Center of Renmin Hospital of Wuhan University (July 2023-July 2024), assessing sleep quality in uveitis patients using the Pittsburgh Sleep Quality Index (PSQI). Based on PSQI scores, patients were categorized into four groups, and their symptoms and characteristics were recorded. Simultaneously, a B10.RIII mouse model of CSD and EAU was developed. Western blotting assessed the phosphorylation of Signal Transducer and Activator of Transcription 1 (STAT1) and the expression of Interferon-Stimulated Gene 15 (ISG15) expression, while immunofluorescence and western blotting evaluated macrophage activity and cytokine secretion. Clinical results showed a strong correlation between poor sleep quality and worsened inflammatory symptoms. In mice, CSD increased STAT1 phosphorylation and ISG15 expression, enhancing macrophage activity and worsening ocular inflammation. Our findings suggest that CSD exacerbates EAU through STAT1 phosphorylation, ISG15 expression, and macrophage activation. The clinical data further support this mechanism, indicating that improving sleep quality could reduce the risk of autoimmune diseases and offering new insights into the connection between sleep and immune function.

Recent advances in structural studies of NLRP3 and NLRP1 inflammasome regulation

The NOD-like receptor (NLR) family comprises inflammasome sensors that are critical intracellular pattern recognition receptors of the innate immune system. The NLR family members NLRP3 and NLRP1 can be activated by a wide range of pathogenic, chemical, self-derived and stress-related stimuli. In recent years, remarkable progress in functional and structural studies of these two receptors have shed light on their complicated and entirely different activation and regulation mechanisms. This review focuses on recent structural studies of NLRP3 and NLRP1, emphasizing the regulatory steps mediated by various activation and inhibitory factors.

Caspases: structural and molecular mechanisms and functions in cell death, innate immunity, and disease

Caspases are critical regulators of cell death, development, innate immunity, host defense, and disease. Upon detection of pathogens, damage-associated molecular patterns, cytokines, or other homeostatic disruptions, innate immune sensors, such as NLRs, activate caspases to initiate distinct regulated cell death pathways, including non-lytic (apoptosis) and innate immune lytic (pyroptosis and PANoptosis) pathways. These cell death pathways are driven by specific caspases and distinguished by their unique molecular mechanisms, supramolecular complexes, and enzymatic properties. Traditionally, caspases are classified as either apoptotic (caspase-2, -3, -6, -7, -8, -9, and -10) or inflammatory (caspase-1, -4, -5, and -11). However, extensive data from the past decades have shown that apoptotic caspases can also drive lytic inflammatory cell death downstream of innate immune sensing and inflammatory responses, such as in the case of caspase-3, -6, -7, and -8. Therefore, more inclusive classification systems based on function, substrate specificity, or the presence of pro-domains have been proposed to better reflect the multifaceted roles of caspases. In this review, we categorize caspases into CARD-, DED-, and short/no pro-domain-containing groups and examine their critical functions in innate immunity and cell death, along with their structural and molecular mechanisms, including active site/exosite properties and substrates. Additionally, we highlight the emerging roles of caspases in cellular homeostasis and therapeutic targeting. Given the clinical relevance of caspases across multiple diseases, improved understanding of these proteins and their structure-function relationships is critical for developing effective treatment strategies.

In vitro assessment of the effect of Porphyra haitanensis polysaccharides on the intestinal flora of allergic mice

This study systematically investigated the modulatory effects of Porphyra haitanensis polysaccharides (PHP) and its two P. haitanensis polysaccharide components (PHP40 and PHP80) on gut microbiota in ovalbumin (OVA)-sensitized mice via in vitro fermentation. PHP40 and PHP80 exhibited sulfate contents of 5.94 ± 0.05 % and 11.72 ± 0.03 %, respectively, with galactose and glucose as dominant monosaccharides. The different polysaccharide components had different effects on the aforementioned changes in the species composition and structure of the gut microbiota in allergic mice, with distinct dominant microbial profiles across groups. PHP could promote Bacillus and Enterococcus proliferation while inhibiting Staphylococcus. PHP40 and PHP80 could promote Enterococcus and Enterobacter growth but suppressed Staphylococcus and Bacillus. Functional prediction indicated PHP significantly improved galactose metabolism and primary/secondary bile acid biosynthesis, potentially alleviating allergic responses.

Macrophage polarization in cancer and beyond: from inflammatory signaling pathways to potential therapeutic strategies

Macrophages are innate immune cells distributed throughout the body that play vital roles in organ development, tissue homeostasis, and immune surveillance. Macrophages acquire a binary M1/M2 polarized phenotype through signaling cascades upon sensing different signaling molecules in the environment, thereby playing a core role in a series of immune tasks, rendering precise regulation essential. M1/M2 macrophage phenotypes regulate inflammatory responses, while controlled activation of inflammatory signaling pathways is involved in regulating macrophage polarization. Among the relevant signaling pathways, we focus on the six well-characterized NF-κB, MAPK, JAK-STAT, PI3K/AKT, inflammasome, and cGAS-STING inflammatory pathways, and elucidate their roles and crosstalk in macrophage polarization. Furthermore, the effects of many environmental signals that influence macrophage polarization are investigated by modulating these pathways in vivo and in vitro. We thus detail the physiological and pathophysiological status of these six inflammatory signaling pathways and involvement in regulating macrophage polarization in cancer and beyond, as well as describe potential therapeutic approaches targeting these signaling pathways. In this review, the latest research advances in inflammatory signaling pathways regulating macrophage polarization are reviewed, as targeting these inflammatory signaling pathways provides suitable strategies to intervene in macrophage polarization and various tumor and non-tumor diseases.

Cell-Autonomous Immunity: From Cytosolic Sensing to Self-Defense

As an evolutionarily conserved and ubiquitous mechanism of host defense, non-immune cells in vertebrates possess the intrinsic ability to autonomously detect and combat intracellular pathogens. This process, termed cell-autonomous immunity, is distinct from classical innate immunity. In this review, we comprehensively examine the defense mechanisms employed by non-immune cells in response to intracellular pathogen invasion. We provide a detailed analysis of the cytosolic sensors that recognize aberrant nucleic acids, lipopolysaccharide (LPS), and other pathogen-associated molecular patterns (PAMPs). Specifically, we elucidate the molecular mechanisms underlying key signaling pathways, including the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mitochondrial antiviral signaling (MAVS) axis, and the guanylate-binding proteins (GBPs)-mediated pathway. Furthermore, we critically evaluate the involvement of these pathways in the pathogenesis of various diseases, including autoimmune disorders, inflammatory conditions, and malignancies, while highlighting their potential as therapeutic targets.

Innate immune sensor NLRP3 drives PANoptosome formation and PANoptosis

Inflammasomes are multiprotein innate immune complexes formed in response to infections, tissue damage, or cellular stress that promote the maturation and release of IL-1β/IL-18 and are implicated in lytic cell death. The NLRP3 inflammasome is canonically activated by an initial priming event followed by an activation stimulus, leading to rapid cell death that occurs through caspase-1 (CASP1) and gasdermin D (GSDMD) activation, called pyroptosis. CASP1- and GSDMD-deficient cells are protected from the rapid LPS plus ATP-induced pyroptosis. However, innate immune responses physiologically occur over time, extending beyond minutes to hours and days. Therefore, in this study, we assessed lytic cell death beyond the early timepoints. While cells lacking the innate immune sensor NLRP3 were protected from cell death induced by the canonical NLRP3 trigger, LPS priming and ATP stimulation (LPS plus ATP), for extended time, CASP1- and GSDMD-deficient cells started to lyse in a time-dependent manner after 2 h. Nevertheless, robust IL-1β and IL-18 release was still dependent on CASP1 activation. These data suggested that NLRP3 engages an additional innate immune, lytic cell death pathway. Indeed, LPS plus ATP induced the activation of caspases and RIPKs associated with PANoptosis in WT cells, and cells deficient in PANoptosis machinery were protected from cell death for extended times. A PANoptosome complex containing NLRP3, ASC, CASP8, and RIPK3 was observed by microscopy in WT, as well as CASP1- or GSDMD-deficient, cells by 30 min post-stimulation. Overall, these findings highlight the central role of NLRP3 as a PANoptosome sensor. Given the physiological role of innate immune cell death, PANoptosis, in health and disease, our study emphasizes the importance of a comprehensive understanding of PANoptosomes, and their components, as therapeutic targets.

Genetic Variants in the NOD-like Receptor Signaling Pathway Are Associated with HIV-1/AIDS in a Northern Chinese Population

The NOD-like receptor (NLR) signaling pathway may influence human immunodeficiency virus (HIV) clearance and CD4+ T cell recovery through inflammatory responses, but its specific mechanism requires further investigation. A deeper understanding of genetic variations can provide new insights into the biological mechanisms underlying the occurrence and development of immunodeficiency syndrome (AIDS). By utilizing multiple bioinformatic analyses and functional annotations, we identified single-nucleotide polymorphisms (SNPs) in the NLR signaling pathway that may affect HIV-1 infection and AIDS progression. Then, a case-control study was performed to screen risk-related variants by genotyping candidate SNPs in a sample of 500 men who have sex with men (MSM) with HIV-1 and 500 healthy controls from the Han population in Northern China. The results revealed significant association between five SNPs (NLRP3 rs4612666, MAVS rs17857295, MAVS rs6084497, MAVS rs16989000, and JAK1 rs4244165) and HIV-1 infection. Interestingly, the gene-gene interaction model composed of five SNPs exhibited a cumulative effect on the disease. Specially, the increase in risk alleles carried by the samples elevated the risk of contracting HIV-1. In addition, three SNPs (IL1B rs1143623, STAT1 rs1467199 and STAT1 rs2066804) were associated with CD4+ T cell counts in patients with AIDS. Three SNPs (OAS1 rs1131454, NLRP3 rs10754558, and MAVS rs867335) were found to be related to the clinical staging of AIDS. This finding provides insights into the genetic variants in NLR signaling pathway genes in HIV-1 infection and AIDS progression among MSM in Northern China.

Overcoming tumor hypoxic bismuth-based ternary heterojunctions enable defect modulation-augmented tumor sonocatalytic immunotherapy

Inducing reactive oxygen species (ROS) via sonocatalysis to initiate inflammatory programmed cell death (PANoptosis) and immunogenic cell death (ICD) presents a promising strategy for activatable cancer immunotherapy. However, the limited ROS generation by sonosensitizers under ultrasound and the immunosuppressive tumor microenvironment hinder the efficiency of sono-immunotherapy. To overcome these challenges, a bismuth-based ternary heterojunction, Bi@Bi2O3-Pt-PEG (BBOP), was developed for sonocatalytic therapy aimed at activating immune responses. This system enhances ROS production during sonocatalysis and leverages dual therapeutic mechanisms by inducing PANoptosis and ICD to achieve improved anti-tumor efficacy. BBOP forms a Z-scheme heterojunction and Schottky contact through the formation of an intermediate Bi2O3 layer and the introduction of Pt. These structures significantly enhance sonocatalytic activity, while the Pt nanozyme exhibits catalase-like behavior, supplying oxygen for sonocatalysis, boosting ROS generation, and effectively relieving tumor hypoxia to reduce immune suppression. Further in vitro and in vivo experiments confirmed BBOP's ability to activate immune responses under ultrasound, inhibiting tumor growth and metastasis. RNA sequencing revealed the therapeutic biological mechanisms. The construction of this catalytic system not only provides insights for optimizing sonosensitizers but also offers a safer and more effective sono-immunotherapy activation strategy and theoretical basis for clinical cancer treatment.

Hyperosmotic stress-induced NLRP3 inflammasome activation via the mechanosensitive PIEZO1 channel in dry eye corneal epithelium

The activation of the NLRP3 inflammasome by hyperosmotic stress is a critical pathophysiological response in dry eye disease (DED), driving the chronic cycle of inflammation on the ocular surface. The specific mechanism underlying hyperosmotic mechanical stimulation activates the NLRP3 inflammasome remains unclear. This study provides evidence that PIEZO1, a mechanosensitive ion channel, functions as the primary receptor for corneal epithelial cells in sensing mechanical stimulation induced by tear hyperosmolarity. Inhibition of PIEZO1 significantly reduces NLRP3 inflammasome-associated pyroptosis in corneal epithelial cells. These findings suggest a therapeutic strategy targeting mechanosensitive ion channels to manage chronic ocular surface inflammation in DED patients. Structured Abstract.

PURPOSE

PIEZO1 modulates the inflammatory response by translating mechanical signals from osmotic pressure into biological processes. This study investigates the functional role of PIEZO1 in activating the NLRP3 inflammasome in corneal epithelial cells under hyperosmotic stress and evaluates its contribution to the pathogenesis of dry eye disease (DED).

METHODS

In the in vitro experiments, immortalized human corneal epithelial cells (HCECs) were cultured under hyperosmotic conditions (450mOsm). For in vivo studies, a dry eye disease mouse model was established by subcutaneous injection of scopolamine (SCOP) in C57BL/6 mice. After successfully inducing the dry eye model, corneal epithelial cell damage was assessed through corneal fluorescein staining scores and TUNEL assays. Protein expression levels were examined via western blotting and immunofluorescence staining, while mRNA expression was analyzed using quantitative RT-PCR. Activation of the NLRP3 inflammasome was evaluated by measuring IL-1β protein cleavage and the formation of ASC speckles.

RESULTS

In the DED model, activation of the NLRP3 inflammasome was detected in corneal epithelial cells, along with increased expression of PIEZO1. The PIEZO1-specific agonist Yoda1 induced upregulation of NLRP3 inflammasome-related gene expression and triggered NLRP3 inflammasome activation. Conversely, silencing PIEZO1 using siRNA or inhibiting its activity suppressed hyperosmotic stress-induced changes in NLRP3 inflammasome-related gene expression and activation. In vivo, PIEZO1 inhibition effectively prevented NLRP3 inflammasome activation in corneal epithelial cells and restored the damaged phenotype associated with dry eye disease.

CONCLUSION

Hyperosmotic stress-induced activation of the NLRP3 inflammasome in corneal epithelial cells is mediated through PIEZO1 activation. The identification of PIEZO1's role in this DED-related pathophysiological response highlights its potential as a therapeutic target for mitigating inflammation in clinical settings.

Unravelling the Role of PANoptosis in Liver Diseases: Mechanisms and Therapeutic Implications

PANoptosis is a multimodal form of cell death that involves inflammatory, apoptotic, and necroptotic pathways, playing a key role in the development of liver diseases. This article first outlines the definition and characteristics of PANoptosis, and then explores its mechanisms of action in different types of liver diseases, including acute liver injury, liver failure, metabolic dysfunction-associated fatty liver disease, and hepatocellular carcinoma. Furthermore, this article analyses the molecular regulatory network of PANoptosis and potential therapeutic targets. Finally, this article summarises the current research on PANoptosis in liver diseases and future research directions, and it reviews the role of the emerging cell death mechanism of PANoptosis in liver diseases.

Exosomes derived from FN14-overexpressing BMSCs activate the NF-κB signaling pathway to induce PANoptosis in osteosarcoma

Despite advances in treatment, the prognosis of osteosarcoma (OS) patients is unsatisfactory, and searching for possible targets is substantial. Fibroblast growth factor inducible type 14 (FN14), a plasma membrane protein, is involved in wound healing, angiogenesis, proliferation, apoptosis, and inflammation. However, its implication in OS development and progression has not been completely characterized. Herein, we explored the cell-to-cell communication of bone marrow mesenchymal stem cells (BMSCs) and OS cells mediated by FN14 in the tumor microenvironment of OS. To assess the interplay between FN14 expression levels and patient survival, FN14 expression was measured in both normal and OS tissues. The FN14 overexpressing BMSCs (OE) were constructed using lentivirus, and exosomes (EXO) were extracted. The uptake of FN14-containing EXO by OS cells was analyzed via flow cytometry and in vivo fluorescence imaging. In addition, high-throughput sequencing was performed to analyze the mechanisms by which EXO inhibits OS cell growth. Finally, the therapeutic effect of OE-EXO was evaluated in a mouse model of OS xenografts. The results showcased reduced FN14 expression in human and mouse OS tissues, suggesting its role may be involved in the malignant progression of OS. The FN14 expression was higher in BMSCs relative to OS cells, and FN14 was secreted and excreted by EXO. The OS cell progression was suppressed after the uptake of FN14-derived EXO from BMSCs. In addition, RNA sequencing revealed that FN14 in EXO activated NF-κB signaling, triggering PANoptosis in OS cells. In vivo, OE-EXO injection inhibited tumor growth in OS xenografts and significantly improved the long-term survival of mice. Our findings suggest that FN14 carried by EXO from BMSCs activates the NF-κB pathway to trigger PANoptosis in OS cells, providing a potential therapeutic strategy to inhibit OS progression.

Mechanistic insights into the anticancer, anti-inflammatory, and antioxidant effects of yellowfin tuna collagen peptides using network pharmacology

Marine-derived collagen peptides have been acknowledged for their therapeutic potential, especially in cancer therapy and inflammation management. The aim of this study was to investigate the molecular mechanisms that contribute to the anticancer, anti-inflammatory and antioxidant properties of yellowfin tuna collagen peptides (YFTCP) utilizing a network pharmacology approach. The YFTCP was extracted from the bones of yellowfin tuna (Thunnus albacares) and subsequently hydrolyzed with trypsin. Seventeen peptides were discovered using liquid chromatography in conjunction with high-resolution mass spectrometry (LC-HRMS). A network pharmacology method was utilized to investigate the interactions between the discovered peptides and their biological targets. Additionally, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to identify pertinent biological pathways involved in the anticancer, antioxidant, and anti-inflammatory effects of these peptides. GO analysis revealed key associations between YFTCP and critical cancer- and inflammation-related genes encoding proteins such as CCND1, SRC, AKT1, IL-1β, TNF, and PPARG, which exhibited significant interactions. These proteins are essential for the regulation of the cell cycle, the development of tumors, and the response to inflammatory stimuli. The KEGG analysis also revealed that YFTCP was involved in a number of critical pathways, such as endocrine resistance, cancer pathways, Kaposi sarcoma-associated herpesvirus infection, proteoglycans in cancer, and human cytomegalovirus infection. These findings highlight the potential use of YFTCP as a multifaceted therapeutic agent, indicating their role in regulating important biological pathways associated with cancer development and inflammation. This study provides new valuable insights into the pharmacological properties of YFTCP, paving the way for future studies and drug development focused on these bioactive peptides.

Dendritic cell maturation in cancer

Dendritic cells (DCs) are specialized antigen-presenting cells that are present at low abundance in the circulation and tissues; they serve as crucial immune sentinels by continually sampling their environment, migrating to secondary lymphoid organs and shaping adaptive immune responses through antigen presentation. Owing to their ability to orchestrate tolerogenic or immunogenic responses to a specific antigen, DCs have a pivotal role in antitumour immunity and the response to immune checkpoint blockade and other immunotherapeutic approaches. The multifaceted functions of DCs are acquired through a complex, multistage process called maturation. Although the role of inflammatory triggers in driving DC maturation was established decades ago, less is known about DC maturation in non-inflammatory contexts, such as during homeostasis and in cancer. The advent of single-cell technologies has enabled an unbiased, high-dimensional characterization of various DC states, including mature DCs. This approach has clarified the molecular programmes associated with DC maturation and also revealed how cancers exploit these pathways to subvert immune surveillance. In this Review, we discuss the mechanisms by which cancer disrupts DC maturation and highlight emerging therapeutic opportunities to modulate DC states. These insights could inform the development of DC-centric immunotherapies, expanding the arsenal of strategies to enhance antitumour immunity.

Liver injury in sepsis: manifestations, mechanisms and emerging therapeutic strategies

Sepsis is defined as a condition related to infection that manifests with multiorgan dysfunction, representing a life-threatening state. Consequently, severe complications frequently occur, with liver injury being one of the most prevalent serious complications of sepsis. Liver dysfunction during sepsis serves as an independent predictor of mortality. This review provides a comprehensive overview of current research on sepsis-induced liver injury (SILI), encompassing the clinical manifestations, diagnostic criteria, pathogenesis and therapeutic strategies associated with this condition. SILI may manifest as hypoxic hepatitis due to ischemia and shock, cholestasis resulting from abnormal bile metabolism, or bile duct sclerosis. The pathophysiology of sepsis involves intricate interactions among the inflammatory response, oxidative stress, and cell death. All of these factors complicate treatment and represent potential targets for therapeutic intervention. Furthermore, this review addresses the limitations inherent in conventional therapies currently employed for managing SILI and emphasizes the potential of novel targeted strategies aimed at addressing the fundamental mechanisms underlying this condition.

Role of triggering receptor expressed on myeloid cells 1/2 in secondary injury after cerebral hemorrhage

Intracerebral hemorrhage (ICH) is a common severe emergency in neurosurgery, causing tremendous economic pressure on families and society and devastating effects on patients both physically and psychologically, especially among patients with poor functional outcomes. ICH is often accompanied by decreased consciousness and limb dysfunction. This seriously affects patients' ability to live independently. Although rapid advances in neurosurgery have greatly improved patient survival, there remains insufficient evidence that surgical treatment significantly improves long-term outcomes. With in-depth pathophysiological studies after ICH, increasing evidence has shown that secondary injury after ICH is related to long-term prognosis and that the key to secondary injury is various immune-mediated neuroinflammatory reactions after ICH. In basic and clinical studies of various systemic inflammatory diseases, triggering receptor expressed on myeloid cells 1/2 (TREM-1/2), and the TREM receptor family is closely related to the inflammatory response. Various inflammatory diseases can be upregulated and downregulated through receptor intervention. How the TREM receptor functions after ICH, the types of results from intervention, and whether the outcomes can improve secondary brain injury and the long-term prognosis of patients are unknown. An analysis of relevant research results from basic and clinical trials revealed that the inhibition of TREM-1 and the activation of TREM-2 can alleviate the neuroinflammatory immune response, significantly improve the long-term prognosis of neurological function in patients with cerebral hemorrhage, and thus improve the ability of patients to live independently.

Cell death in acute lung injury: caspase-regulated apoptosis, pyroptosis, necroptosis, and PANoptosis

There has been abundant research on the variety of programmed cell death pathways. Apoptosis, pyroptosis, and necroptosis under the action of the caspase family are essential for the innate immune response. Caspases are classified into inflammatory caspase-1/4/5/11, apoptotic caspase-3/6/7, and caspase-2/8/9/10. Although necroptosis is not caspase-dependent to transmit cell death signals, it can cross-link with pyroptosis and apoptosis signals under the regulation of caspase-8. An increasing number of studies have reiterated the involvement of the caspase family in acute lung injuries caused by bacterial and viral infections, blood transfusion, and ventilation, which is influenced by noxious stimuli that activate or inhibit caspase engagement pathways, leading to subsequent lung injury. This article reviews the role of caspases implicated in diverse programmed cell death mechanisms in acute lung injury and the status of research on relevant inhibitors against essential target proteins of the described cell death mechanisms. The findings of this review may help in delineating novel therapeutic targets for acute lung injury.

Ubiquitin Ligases in Control: Regulating NLRP3 Inflammasome Activation

Ubiquitin ligases play pivotal roles in the regulation of NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, a critical process in innate immunity and inflammatory responses. This review explores the intricate mechanisms by which various E3 ubiquitin ligases exert both positive and negative influences on NLRP3 inflammasome activity through diverse post-translational modifications. Negative regulation of NLRP3 inflammasome assembly is mediated by several E3 ligases, including F-box and leucine-rich repeat protein 2 (FBXL2), tripartite motif-containing protein 31 (TRIM31), and Casitas B-lineage lymphoma b (Cbl-b), which induce K48-linked ubiquitination of NLRP3, targeting it for proteasomal degradation. Membrane-associated RING-CH 7 (MARCH7) similarly promotes K48-linked ubiquitination leading to autophagic degradation, while RING finger protein (RNF125) induces K63-linked ubiquitination to modulate NLRP3 function. Ariadne homolog 2 (ARIH2) targets the nucleotide-binding domain (NBD) domain of NLRP3, inhibiting its activation, and tripartite motif-containing protein (TRIM65) employs dual K48 and K63-linked ubiquitination to suppress inflammasome assembly. Conversely, Pellino2 exemplifies a positive regulator, promoting NLRP3 inflammasome activation through K63-linked ubiquitination. Additionally, ubiquitin ligases influence other components critical for inflammasome function. TNF receptor-associated factor 3 (TRAF3) mediates K63 polyubiquitination of apoptosis-associated speck-like protein containing a CARD (ASC), facilitating its degradation, while E3 ligases regulate caspase-1 activation and DEAH-box helicase 33 (DHX33)-NLRP3 complex formation through specific ubiquitination events. Beyond direct inflammasome regulation, ubiquitin ligases impact broader innate immune signaling pathways, modulating pattern-recognition receptor responses and dendritic cell maturation. Furthermore, they intricately control NOD1/NOD2 signaling through K63-linked polyubiquitination of receptor-interacting protein 2 (RIP2), crucial for nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we explore how various pathogens, including bacteria, viruses, and parasites, have evolved sophisticated strategies to hijack the host ubiquitination machinery, manipulating NLRP3 inflammasome activation to evade immune responses. This comprehensive analysis provides insights into the molecular mechanisms underlying inflammasome regulation and their implications for inflammatory diseases, offering potential avenues for therapeutic interventions targeting the NLRP3 inflammasome. In conclusion, ubiquitin ligases emerge as key regulators of NLRP3 inflammasome activation, exhibiting a complex array of functions that finely tune immune responses. Understanding these regulatory mechanisms not only sheds light on fundamental aspects of inflammation but also offers potential therapeutic avenues for inflammatory disorders and infectious diseases.

Zika virus inhibits cell death by inhibiting the expression of NLRP3 and A20

Zika virus (ZIKV) is associated with microcephaly in neonates and neurological disorders in adults. Chronic ZIKV infection has been identified in the testes, indicating that the virus can lead to prolonged illness, yet its pathogenesis remains poorly understood. Here, we found that ZIKV infection does not induce significant cell death in mouse macrophages despite the critical role that cell death plays in the antiviral immune response. Furthermore, we discovered that ZIKV infection impairs the activation of the NLPR3-dependent inflammasome and inhibits apoptosis. Consequently, we investigated the regulatory mechanism of the NLRP3 inflammasome and apoptosis in the context of ZIKV infection. Our results revealed significant reductions in the protein expression levels of NLRP3 and A20, attributable to post-transcriptional or translational effects during ZIKV infection. These findings suggest that ZIKV infection may disrupt cell death pathways, leading to its pathogenicity.IMPORTANCEZika virus (ZIKV), first isolated from a nonhuman primate in Africa in 1947, was relatively understudied until 2016. By then, ZIKV had already been reported in more than 20 countries and territories. The infection poses a significant risk, as it is associated with microcephaly in infants and neurological disorders in adults; however, the underlying mechanisms responsible for these severe outcomes remain unclear. In this study, we demonstrate that ZIKV infection significantly reduces the expression of NLRP3 and A20 proteins through post-transcriptional or translational processes, which leads to inhibited cell death. These findings are critical because cell death plays a vital role in the host's antiviral immune response. Our findings highlight how ZIKV infection compromises essential cell death pathways, raising serious concerns about its pathogenesis. A comprehensive understanding of this disruption is vital for developing targeted interventions to mitigate the virus' impact on public health.

Portimine A toxin causes skin inflammation through ZAKα-dependent NLRP1 inflammasome activation

In 2020-2021, a "mysterious illness" struck Senegalese fishermen, causing severe acute dermatitis in over one thousand individuals following exposure through drift-net fishing activity. Here, by performing deep analysis of the environmental samples we reveal the presence of the marine dinoflagellate Vulcanodinium rugosum and its associated cyclic imine toxins. Specifically, we show that the toxin PortimineA, strongly enriched in environmental samples, impedes ribosome function in human keratinocytes, which subsequently activates the stress kinases ZAKα and P38 and promotes the nucleation of the human NLRP1 inflammasome, leading to the release of IL-1β/IL-18 pro-inflammatory cytokines and cell death. Furthermore, cell-based models highlight that naturally occurring mutations in the P38-targeted sites of human NLRP1 are unable to respond to PortimineA exposure. Finally, the development and use of human organotypic skins and zebrafish models of PortimineA exposure demonstrate that the ZAKα-NLRP1 axis drives skin necrosis and inflammation. Our results exemplify the threats to human health caused by emerging environmental toxins and identify ZAKα and NRLP1 as important pharmacological targets to mitigate PortimineA toxicity.

ChNLRC4, a cytoplasmic pattern recognition receptor, activates the pyroptosis signaling pathway in Mollusca

NLR inflammasomes recognize pathogen-associated molecular patterns (PAMPs), triggering Caspase-1 activation and leading to gasdermin D (GSDMD)-mediated pyroptosis, a crucial immune response in mammals. The functional GSDME-mediated pyroptosis has been reported in invertebrates, yet the existence of an NLR-Caspase-GSDME axis mediating pyroptosis signaling cascades remains unclear. In this study, we reported an NLRC4 homolog named ChNLRC4, a pattern recognition receptor from the oyster Crassostrea hongkongensis that is able to bind to LPS and Lys-type PGN through its LRR domain. ChNLRC4 interacted with ChCaspase-1 through CARD-CARD domain homotypic interactions and enhanced ChCaspase-1 activity. Additionally, overexpression of ChNLRC4 promoted ChCaspase-1-mediated cleavage of ChGSDME, leading to pyroptosis in HEK293T cells. Furthermore, knockdown of chnlrc4 resulted in a significant reduction in the death rate of hemocytes, immune infiltration of hemocytes, cilium shedding, and bacterial clearance. Collectively, this study provides insight into the role of NLR within the pyroptosis signaling pathway in oysters.

Regulation of pattern recognition receptor signaling by palmitoylation

Pattern recognition receptors (PRRs), consisting of Toll-like receptors, RIG-I-like receptors, cytosolic DNA sensors, and NOD-like receptors, sense exogenous pathogenic molecules and endogenous damage signals to maintain physiological homeostasis. Upon activation, PRRs stimulate the sensitization of nuclear factor κB, mitogen-activated protein kinase, TANK-binding kinase 1-interferon (IFN) regulatory factor, and inflammasome signaling pathways to produce inflammatory factors and IFNs to activate Janus kinase/signal transducer and activator of transcription signaling pathways, resulting in anti-infection, antitumor, and other specific immune responses. Palmitoylation is a crucial type of post-translational modification that reversibly alters the localization, stability, and biological activity of target molecules. Here, we discuss the available knowledge on the biological roles and underlying mechanisms linked to protein palmitoylation in modulating PRRs and their downstream signaling pathways under physiological and pathological conditions. Moreover, recent advances in the use of palmitoylation as an attractive therapeutic target for disorders caused by the dysregulation of PRRs were summarized.

Innate Immune Sensors and Cell Death-Frontiers Coordinating Homeostasis, Immunity, and Inflammation in Skin

The skin provides a life-sustaining interface between the body and the external environment. A dynamic communication among immune and non-immune cells in the skin is essential to ensure body homeostasis. Dysregulated cellular communication can lead to the manifestation of inflammatory skin conditions. In this review, we will focus on the following two key frontiers in the skin: innate immune sensors and cell death, as well as their cellular crosstalk in the context of skin homeostasis and inflammation. This review will highlight the recent advancements and mechanisms of how these pathways integrate signals and orchestrate skin immunity, focusing on inflammatory skin diseases and skin infections in mice and humans.

Tumor microenvironment regulation by reactive oxygen species-mediated inflammasome activation

Tumor microenvironment (TME) is composed of diverse cell types whose interactions, both direct and indirect, significantly influence tumorigenesis and therapeutic outcomes. Within TME, reactive oxygen species (ROS) are produced by various cells and exhibit a dual role: moderate ROS levels promote tumor initiation and progression, whereas excessive levels induce cancer cell death, influencing the efficacy of anticancer therapies. Inflammasomes, cytosolic multiprotein complexes, are pivotal in multiple stages of tumorigenesis and play a crucial role in establishing the inflammatory TME. By releasing cytokines such as IL-1β and IL-18, inflammasomes contribute to immune cell recruitment and sustain a chronic inflammatory state that supports tumor growth. ROS are critical regulators of inflammasome activation, with the impact of ROS-mediated activation differing across cell types, leading to distinct influences on tumor progression and therapeutic responses. This review explores how ROS drive inflammasome activation in various TME-associated cells and the reciprocal ROS generation induced by inflammasomes, examining their multifaceted impact on tumorigenesis and therapeutic efficacy. By elucidating the complex interplay between ROS and inflammasomes in TME, we provide insights into potential therapeutic approaches that could modulate cancer progression and enhance treatment outcomes.

DAMPs, PAMPs, NLRs, RIGs, CLRs and TLRs - Understanding the Alphabet Soup in the Context of Bone Biology

PURPOSE OF REVIEW

The purpose of this review is to summarize the current understanding of cell-autonomous innate immune pathways that contribute to bone homeostasis and disease.

RECENT FINDINGS

Germ-line encoded pattern recognition receptors (PRRs) are the first line of defense against danger and infections. In the bone microenvironment, PRRs and downstream signaling pathways, that mount immune defense, interface intimately with the core cellular processes in bone cells to alter bone formation and resorption. The role of PRR engagement on bone remodeling has been best described as a result of activated macrophages secreting effector molecules that reshape the characteristics of bone-resident cells. However, it is being increasingly recognized that local bone resident-cells like osteoclasts and osteoblasts possess an arsenal of PRRs. The engagement of these PRRs by stimuli in the bone niche can drive cell-autonomous (aka cell-intrinsic) responses that, in turn, impact bone-remodeling dramatically, irrespective of immune cell effectors. Indeed, this vital role for cell-autonomous innate immune responses is evident in how reduced PRR activity within osteoclast progenitors correlates with their reduced differentiation and abnormal bone remodeling. Further, cell-intrinsic PRR activity has now been shown to influence the behavior of osteoblasts, osteocytes and other local immune/non-immune cell populations. However, distinct PRR families have varying impact on bone homeostasis and inflammation, emphasizing the importance of investigating these different nodes of innate immune signaling in bone cells to better identify how they synergistically and/or antagonistically regulate bone remodeling in the course of an immune response. Innate immune sensing within bone resident cells is a critical determinant for bone remodeling in health and disease.

Role of inflammasomes and neuroinflammation in epilepsy

Epilepsy is a brain disorder characterized by recurrent seizures, which are brief episodes of abnormal electrical activity in the brain and involuntary movement that can lead to physical injury and loss of consciousness. Seizures are canonically accompanied by increased inflammatory cytokine production that promotes neuroinflammation, brain pathology, and seizure propagation. Understanding the source of pro-inflammatory cytokines which promote seizure pathogenesis could be a gateway to precision epilepsy drug design. This review discusses the inflammasome in epilepsy including its role in seizure propagation and negative impacts on brain health. The inflammasome is a multiprotein complex that coordinates IL-1β and IL-18 production in response to tissue damage, cellular stress, and infection. Clinical evidence for inflammasome signaling in epileptogenesis is reviewed followed by a discussion of emerging strategies to modulate inflammasome activity in epilepsy.

MAP Kinase Signaling at the Crossroads of Inflammasome Activation

Inflammasomes are crucial mediators of both antimicrobial host defense and inflammatory pathology, requiring stringent regulation at multiple levels. This review explores the pivotal role of mitogen-activated protein kinase (MAPK) signaling in modulating inflammasome activation through various regulatory mechanisms. We detail recent advances in understanding MAPK-mediated regulation of NLRP3 inflammasome priming, licensing and activation, with emphasis on MAPK-induced activator protein-1 (AP-1) signaling in NLRP3 priming, ERK1 and JNK in NLRP3 licensing, and TAK1 in connecting death receptor signaling to NLRP3 inflammasome activation. Furthermore, we discuss novel insights into MAPK signaling in human NLRP1 inflammasome activation, focusing on the MAP3K member ZAKα as a key kinase linking ribosomal stress to inflammasome activation. Lastly, we review recent work elucidating how Bacillus anthracis lethal toxin (LeTx) manipulates host MAPK signaling to induce macrophage apoptosis as an immune evasion strategy, and the counteraction of this effect through genotype-specific Nlrp1b inflammasome activation in certain rodent strains.

A comprehensive review of sensors of radiation-induced damage, radiation-induced proximal events, and cell death

Radiation, a universal component of Earth's environment, is categorized into non-ionizing and ionizing forms. While non-ionizing radiation is relatively harmless, ionizing radiation possesses sufficient energy to ionize atoms and disrupt DNA, leading to cell damage, mutation, cancer, and cell death. The extensive use of radionuclides and ionizing radiation in nuclear technology and medical applications has sparked global concern for their capacity to cause acute and chronic illnesses. Ionizing radiation induces DNA damage either directly through strand breaks and base change or indirectly by generating reactive oxygen species (ROS) and reactive nitrogen species (RNS) via radiolysis of water. This damage triggers a complex cellular response involving recognition of DNA damage, cell cycle arrest, DNA repair mechanisms, release of pro-inflammatory cytokines, and cell death. This review focuses on the mechanisms of radiation-induced cellular damage, recognition of DNA damage and subsequent activation of repair processes, and the critical role of the innate immune response in resolution of the injury. Emphasis is placed on pattern recognition receptors (PRRs) and related receptors that detect damage-associated molecular patterns (DAMPs) and initiate downstream signaling pathways. Radiation-induced cell death pathways are discussed in detail. Understanding these processes is crucial for developing strategies to mitigate the harmful effects of radiation and improve therapeutic outcomes.

Growth Hormone, Hypothalamic Inflammation, and Aging

While inflammation is a crucial response in injury repair and tissue regeneration, chronic inflammation is a prevalent feature in various chronic, non-communicable diseases such as obesity, diabetes, and cancer and in cardiovascular and neurodegenerative diseases. Long-term inflammation considerably affects disease prevalence, quality of life, and longevity. Our research indicates that the growth hormone/insulin-like growth factor 1 (GH/IGF-1) axis is a pivotal regulator of inflammation in some tissues, including the hypothalamus, which is a key player in systemic metabolism regulation. Moreover, the GH/IGF-1 axis is strongly linked to longevity, as GH- or GH receptor-deficient mice live approximately twice as long as wild-type animals and exhibit protection against aging-induced inflammation. Conversely, GH excess leads to increased neuroinflammation and reduced longevity. Our review studies the associations between the GH/IGF-1 axis, inflammation, and aging, with a particular focus on evidence suggesting that GH receptor signaling directly induces hypothalamic inflammation. This finding underscores the significant impact of changes in the GH axis on metabolism and on the predisposition to chronic, non-communicable diseases.

Platelet's plea to Immunologists: Please do not forget me

Platelets are non-nucleated mammalian cells originating from the cytoplasmic expulsion of the megakaryocytes. Megakaryocytes develop during hematopoiesis through megakaryopoiesis, whereas platelets develop from megakaryocytes through thrombopoiesis. Since their first discovery, platelets have been studied as critical cells controlling hemostasis or blood coagulation. However, coagulation and innate immune response are evolutionarily linked processes. Therefore, it has become critical to investigate the immunological functions of platelets to maintain immune homeostasis. Advances in immunology and platelet biology research have explored different critical roles of platelets, including phagocytosis, release of different immune mediators, and controlling functions of different immune cells by direct interaction and immune mediators. The current article discusses platelet's development and their critical role as innate immune cells, which express different pattern recognition receptors (PRRs), recognizing different pathogen or microbe-associated molecular patterns (PAMPs or MAMPs) and death/damage-associated molecular patterns (DAMPs) and their direct interactions with innate and adaptive immune cells to maintain immune homeostasis.

Fexuprazan safeguards the esophagus from hydrochloric acid-induced damage by suppressing NLRP1/Caspase-1/GSDMD pyroptotic pathway

Introduction

Proton pump inhibitors (PPIs) and potassium-competitive acid blockers (P-CABs) are widely used to manage gastric acid-related disorders by inhibiting hydrochloric acid (HCl) secretion from parietal cells in the stomach. Although PPIs are known to have anti-inflammatory properties beyond their role in inhibiting gastric acid secretion, research on P-CABs is lacking. In this study, we aimed to investigate whether all available P-CABs exhibit anti-inflammatory effects in gastroesophageal reflux-induced esophagitis and to elucidate the underlying mechanisms.

Methods

Het-1A cells, normal esophageal epithelial cells, were treated with HCl (pH 4) for 30 min. Esomeprazole, a representative PPI, and three currently marketed P-CABs (vonoprazan, tegoprazan, and fexuprazan) were used for pretreatment. Total RNA sequencing was performed using Het-1A cells pretreated with 1% DMSO or fexuprazan, followed by exposure to HCl. Pyroptosis was measured using lactate dehydrogenase (LDH) release and Annexin V-FITC/PI staining. Western blotting, qRT-PCR, and ELISA were used to determine the expression of the related genes.

Results

Pretreatment with esomeprazole, vonoprazan, tegoprazan, and fexuprazan significantly inhibited the HCl-induced pro-inflammatory cytokines, including IL-6, IL-8, IL-1β, and TNF-α. Fexuprazan and vonoprazan significantly attenuated the HCl-induced pyroptosis rate, as assessed by elevated LDH release and Annexin V-FITC/PI staining, whereas esomeprazole and tegoprazan did not. RNA sequencing revealed that NOD-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) was significantly reduced in Het-1A cells pretreated with fexuprazan compared to those treated with DMSO. Fexuprazan and vonoprazan markedly reduced the HCl-induced transcriptional and translational expression of genes involved in the pyroptosis pathway, including NLRP1, Caspase-1, gasdermin D, and IL-1β. Notably, fexuprazan reduced the HCl-induced increase in pyroptosis and IL-1β using siRNA, even in the presence of NLRP1 knockdown. Fexuprazan, tested on inflammatory THP-1 macrophage cells, significantly reduced NLRP1 expression and inhibited lipopolysaccharide-induced pyroptosis.

Conclusion

Our findings reveal that all p-CABs exhibit anti-inflammatory properties, while fexuprazan inhibits inflammation and pyroptosis of esophageal cells caused by the gastric acid. Therefore, it is presumed to have additional benefits in gastroesophageal reflux disease in addition to suppressing gastric acid secretion.

Porcine Epidemic Diarrhea Virus Infection of Porcine Intestinal Epithelial Cells Causes Mitochondrial DNA Release and the Activation of the NLRP3 Inflammasome to Mediate Interleukin-1β Secretion

Porcine epidemic diarrhea virus (PEDV) induces enteritis and diarrhea in piglets. Mitochondrial DNA (mtDNA) contributes to virus-induced inflammatory responses; however, the involvement of inflammasomes in PEDV infection responses remains unclear. We investigated the mechanism underlying inflammasome-mediated interleukin (IL)-1β secretion during the PEDV infection of porcine intestinal epithelial (IPEC-J2) cells. IL-1β production and caspase-1 activity were assessed by quantitative PCR and enzyme-linked immunosorbent assay. NLRP3 inflammasome activation was assessed using immunoprecipitation experiments. Mitochondrial damage was evaluated by analyzing the mitochondrial membrane potential and ATP levels and by the flow cytometry examination of mitochondrial reactive oxygen species (mtROS). Mitochondria and mtDNA localization were observed using immunofluorescence. The inhibition of mtROS and mtDNA production allowed NLRP3 inflammasome and IL-1β expression detection and the evaluation of the pathway underlying NLRP3 inflammasome activation in PEDV-infected IPEC-J2 cells. IPEC-J2 cells upregulated IL-1β upon PEDV infection, where mature IL-1β secretion depended on caspase-1 activity, triggered NLRP3 inflammasome expression and assembly, and caused mitochondrial dysfunction, leading to mtDNA release and NLRP3 inflammasome activation, while mtROS contributed to NF-κB pathway activation, enhancing IL-1β secretion. This is the first demonstration of the mechanism underlying mtDNA release and NLRP3 inflammasome activation facilitating IL-1β secretion from PEDV-infected IPEC-J2 cells. These data enhance our understanding of the inflammatory mechanisms triggered by PEDV.

Levin T. Evolutionary Dynamics of Proinflammatory Caspases in Primates and Rodents

Caspase-1 and related proteases are key players in inflammation and innate immunity. Here, we characterize the evolutionary history of caspase-1 and its close relatives across 19 primates and 21 rodents, focusing on differences that may cause discrepancies between humans and animal studies. While caspase-1 has been retained in all these taxa, other members of the caspase-1 subfamily (caspase-4, caspase-5, caspase-11, and caspase-12 and CARD16, 17, and 18) each have unique evolutionary trajectories. Caspase-4 is found across simian primates, whereas we identified multiple pseudogenization and gene loss events in caspase-5, caspase-11, and the CARDs. Because caspase-4 and caspase-11 are both key players in the noncanonical inflammasome pathway, we expected that these proteins would be likely to evolve rapidly. Instead, we found that these two proteins are largely conserved, whereas caspase-4's close paralog, caspase-5, showed significant indications of positive selection, as did primate caspase-1. Caspase-12 is a nonfunctional pseudogene in humans. We find this extends across most primates, although many rodents and some primates retain an intact, and likely functional, caspase-12. In mouse laboratory lines, we found that 50% of common strains carry nonsynonymous variants that may impact the functions of caspase-11 and caspase-12 and therefore recommend specific strains to be used (and avoided). Finally, unlike rodents, primate caspases have undergone repeated rounds of gene conversion, duplication, and loss leading to a highly dynamic proinflammatory caspase repertoire. Thus, we uncovered many differences in the evolution of primate and rodent proinflammatory caspases and discuss the potential implications of this history for caspase gene functions.

Inflammasomes in Intestinal Disease: Mechanisms of Activation and Therapeutic Strategies

NOD-like receptors (NLRs) are a family of cytosolic pattern recognition receptors (PRRs) implicated in the innate immune sensing of pathogens and damage signals. NLRs act as sensors in multi-protein complexes called inflammasomes. Inflammasome activity is necessary for the maintenance of intestinal homeostasis, although their aberrant activation contributes to the pathogenesis of several gastrointestinal diseases. In this review, we summarize the main features of the predominant types of inflammasomes involved in gastrointestinal immune responses and their implications in intestinal disease, including Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), celiac disease, and Colorectal Cancer (CRC). In addition, we report therapeutic discoveries that target the inflammasome pathway, highlighting promising novel therapeutic strategies in the treatment of intestinal diseases. Collectively, our understanding of the mechanisms of intestinal inflammasome activation and their interactions with other immune pathways appear to be not fully elucidated. Moreover, the clinical relevance of the efficacy of inflammasome inhibitors has not been evaluated. Despite these limitations, a greater understanding of the effectiveness, specificity, and reliability of pharmacological and natural inhibitors that target inflammasome components could be an opportunity to develop new therapeutic options for the treatment of intestinal disease.

Distinct Inflammatory Programs Underlie the Intramuscular Lipid Nanoparticle Response

Developments in mRNA/lipid nanoparticle (LNP) technology have advanced the fields of vaccinology and gene therapy, raising questions about immunogenicity. While some mRNA/LNPs generate an adjuvant-like environment in muscle tissue, other mRNA/LNPs are distinct in their capacity for multiple rounds of therapeutic delivery. We evaluate the adjuvancy of components of mRNA/LNPs by phenotyping cellular infiltrate at injection sites, tracking uptake by immune cells, and assessing the inflammatory state. Delivery of 9 common, but chemically distinct, LNPs to muscle revealed two classes of inflammatory gene expression programs: inflammatory (Class A) and noninflammatory (Class B). We find that intramuscular injection with Class A, but not Class B, empty LNPs (eLNPs) induce robust neutrophil infiltration into muscle within 2 h and a diverse myeloid population within 24 h. Single-cell RNA sequencing revealed SM-102-mediated expression of inflammatory chemokines by myeloid infiltrates within muscle 1 day after injection. Surprisingly, we found direct transfection of muscle infiltrating myeloid cells and splenocytes 24 h after intramuscular mRNA/LNP administration. Transfected myeloid cells within the muscle exhibit an activated phenotype 24 h after injection. Similarly, directly transfected splenic lymphocytes and dendritic cells (DCs) are differentially activated by Class A or Class B containing mRNA/LNP. Within the splenic DC compartment, type II conventional DCs (cDC2s) are directly transfected and activated by Class A mRNA/LNP. Together, we show that mRNA and LNPs work synergistically to provide the necessary innate immune stimuli required for effective vaccination. Importantly, this work provides a design framework for vaccines and therapeutics alike.

Comprehensive analysis of adverse outcome pathway, potency, human exposure supports carcinogenicity of polyhexamethylene guanidine phosphate in lung cancer

In this study, we investigated the potential mechanisms by which polyhexamethylene guanidine phosphate (PHMG-p), a known respiratory irritant, may contribute to lung cancer development. Using the adverse outcome pathway (AOP) framework, we analyzed established databases (such as AOP-Wiki) and employed AI tools (AOP-helpFinder) to identify key events (KEs) associated with lung carcinogenesis. Our analysis indicates that chronic inhalation of PHMG-p triggers a non-genotoxic pathway, characterized by cell membrane disruption, inflammation, and oxidative stress, with a point of departure (POD) of 0.0018 mg/m³, suggesting carcinogenic potential. Additionally, a human exposure assessment revealed that most claimants were exposed to PHMG-p levels exceeding the estimated inhalation reference concentration (RfC) of 0.018 µg/m³. While downstream KEs, such as DNA damage, mutation, and cell proliferation, require further investigation, our findings, supported by the AOP framework and potency and exposure assessments, strongly suggest that PHMG-p exposure could induce lung cancer in individuals affected by humidifier disinfectants. These results underscore the importance of a comprehensive risk assessment approach for evaluating the carcinogenicity of PHMG-p.

Inflammasome complex genes with clinical relevance suggest potential as therapeutic targets for anti-tumor drugs in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a challenging malignancy characterized by intricate biology and clinical characteristics. Despite advancements in treatment strategies, the molecular mechanisms underlying ccRCC initiation, progression, and therapeutic resistance remain elusive. Inflammasomes, multi-protein complexes involved in innate immunity and inflammation, have emerged as potential regulators in cancers. However, their involvement and mechanisms in ccRCC remain poorly understood. In this study, we conducted a systematic investigation into the expression patterns and clinical significance of inflammasome complexes in ccRCC. We found the perturbation of inflammasome complexes genes was related to patient's prognosis and other clinical characteristics. By developing an Inflammasome Complexes (IFC) score and identifying IFC subtypes with distinct clinical characteristics and oncogenic roles, our study suggested that inflammasome activation could impact tumorigenesis and modulate the tumor immune landscape, particularly its positive correlations with immunosuppressive macrophages. Furthermore, our study revealed the potential of inflammasome complex genes as predictive markers for patient responses to various anti-tumor drugs, including Osimertinib, Ulixertinib, Telomerase Inhibitor IX, and GSK2578215A. These findings have significant clinical implications and offer opportunities for guiding treatment strategies and improving patient outcomes of ccRCC.

A disease resistance protein triggers oligomerization of its NLR helper into a hexameric resistosome to mediate innate immunity

NRCs are essential helper NLR (nucleotide-binding domain and leucine-rich repeat) proteins that execute immune responses triggered by sensor NLRs. The resting state of NbNRC2 was recently shown to be a homodimer, but the sensor-activated state remains unclear. Using cryo-EM, we determined the structure of sensor-activated NbNRC2, which forms a hexameric inflammasome-like resistosome. Mutagenesis of the oligomerization interface abolished immune signaling, confirming the functional significance of the NbNRC2 resistosome. Comparative structural analyses between the resting state homodimer and sensor-activated homohexamer revealed substantial rearrangements, providing insights into NLR activation mechanisms. Furthermore, structural comparisons between NbNRC2 hexamer and previously reported CC-NLR pentameric assemblies revealed features allowing an additional protomer integration. Using the NbNRC2 hexamer structure, we assessed the recently released AlphaFold 3 for predicting activated CC-NLR oligomers, revealing high-confidence modeling of NbNRC2 and other CC-NLR amino-terminal α1 helices, a region proven difficult to resolve structurally. Overall, our work sheds light on NLR activation mechanisms and expands understanding of NLR structural diversity.

Weighted gene co-expression network analysis and single-cell sequence analysis uncover immune landscape and reveal hub genes of necroptosis in macrophages in myocardial ischaemia-reperfusion injury

Myocardial ischaemia-reperfusion injury (MIRI) caused by the treatment of acute myocardial infarction (AMI) is the primary cause of severe ventricular remodelling, heart failure (HF), and high mortality. In recent studies, research on the role of necroptosis in MIRI has focused on cardiomyocytes, but new biomarkers and immunocyte mechanisms of necroptosis are rarely studied. In the present study, weighted gene co-expression network analysis (WGCNA) algorithms were used to establish a weighted gene co-expression network, and Casp1, Hpse, Myd88, Ripk1, and Tpm3 were identified as biological markers of necroptosis using least absolute shrinkage, selection operator (LASSO) regression and support vector machine (SVM) feature selection algorithms. The role and discriminatory power of these five genes in MIRI had never been studied. Single-cell and cell-talk analyses showed that hub genes of necroptosis were focused on macrophages, which mediate the functions of monocytes, fibroblasts, haematopoietic stem cells, and cardiomyocytes, primarily through the TNF/TNFRSF1A interaction. The polarisation and functional activation of macrophages were affected by the MIF signalling network (MIF CD74/CXCR4 and MIF CD74/CD44) of other cells. The results of the immune infiltration assay showed that the five genes involved in necroptosis were significantly related to the infiltration and functional activity of M2 macrophages. TWS-119 is predicted to be a molecular drug that targets key MIRI genes. A mouse model was established to confirm the expression of five hub genes, and ventricular remodelling increased with time after ischaemia-reperfusion injury (IRI). Therefore, Casp1, Hpse, Myd88, Ripk1, and Tpm3 may be key genes regulating necroptosis and polarisation in macrophages, and causing ventricular remodelling.

Prognostic value of neutrophil to lymphocyte ratio for patients with bladder cancer undergoing radical cystectomy: a systematic review and meta-analysis

Objectives

This study evaluated the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) for survival outcomes in bladder cancer patients treated with radical cystectomy.

Methods

Studies assessing NLR's prognostic significance for bladder cancer after radical cystectomy were identified from PubMed, Embase, Web of Science, and Cochrane databases until April 2024. Survival outcomes analyzed included overall survival (OS), disease-free survival (DFS), relapse-free survival (RFS), cancer-specific survival (CSS), and progression-free survival (PFS).

Results

The meta-analysis comprised 15 cohort studies with 8,448 patients. Multivariate analysis showed significantly shorter OS, CSS, DFS, and RFS in the high NLR group compared to the low NLR group. However, no significant difference in PFS was observed between the groups.

Conclusions

NLR serves as an independent prognostic indicator for bladder cancer patients undergoing radical cystectomy, with elevated NLR associated with poorer survival. Further large-scale, prospective studies are warranted to validate the relationship between NLR and prognosis in bladder cancer.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024549573.

Beyond Inflammation: Role of Pyroptosis Pathway Activation by Gram-Negative Bacteria and Their Outer Membrane Vesicles (OMVs) in the Interaction with the Host Cell

Pyroptosis is a gasdermin-mediated pro-inflammatory programmed cell death that, during microbial infections, aims to restrict the spreading of bacteria. Nevertheless, excessive pyroptosis activation leads to inflammation levels that are detrimental to the host. Pathogen-associated molecular patterns (PAMPs) present in bacteria and outer membrane vesicles (OMVs) can trigger pyroptosis pathways in different cell types with different outcomes. Moreover, some pathogens have evolved virulence factors that directly interfere with pyroptosis pathways, like Yersinia pestis YopM and Shigella flexneri IpaH7.8. Other virulence factors, such as those of Neisseria meningitidis, Neisseria gonorrhoeae, Salmonella enterica, and Helicobacter pylori affect pyroptosis pathways indirectly with important differences between pathogenic and commensal species of the same family. These pathogens deserve special attention because of the increasing antimicrobial resistance of S. flexneri and N. gonorrhoeae, the high prevalence of S. enterica and H. pylori, and the life-threatening diseases caused by N. meningitidis and Y. pestis. While inflammation due to macrophage pyroptosis has been extensively addressed, the effects of activation of pyroptosis pathways on modulation of cell cytoskeleton and cell-cell junctions in epithelia and endothelia and on the bacterial crossing of epithelial and endothelial barriers have only been partly investigated. Another important point is the diverse consequences of pyroptosis pathways on calcium influx, like activation of calcium-dependent enzymes and mitochondria dysregulation. This review will discuss the pyroptotic pathways activated by Gram-negative bacteria and their OMVs, analyzing the differences between pathogens and commensal bacteria. Particular attention will also be paid to the experimental models adopted and the main results obtained in the different models. Finally, strategies adopted by pathogens to modulate these pathways will be discussed with a perspective on the use of pyroptosis inhibitors as adjuvants in the treatment of infections.

The Role of Inflammasome-Associated Innate Immune Receptors in Cancer

Dysregulated activation of the innate immune system is a critical driver of chronic inflammation that is associated with at least 30% of all cancers. Innate immunity can also exert tumour-promoting effects (e.g. proliferation) directly on cancer cells in an intrinsic manner. Conversely, innate immunity can influence adaptive immunity-based anti-tumour immune responses via Ag-presenting dendritic cells that activate natural killer and cytotoxic T cells to eradicate tumours. While adaptive anti-tumour immunity has underpinned immunotherapy approaches with immune checkpoint inhibitors and chimeric Ag receptor-T cells, the clinical utility of innate immunity in cancer is underexplored. Innate immune responses are governed by pattern recognition receptors, which comprise several families, including Toll-like, nucleotide-binding oligomerization domain-containing (NOD)-like and absent-in-melanoma 2 (AIM2)-like receptors. Notably, a subset of NOD-like and AIM2-like receptors can form large multiprotein "inflammasome" complexes which control maturation of biologically active IL-1β and IL-18 cytokines. Over the last decade, it has emerged that inflammasomes can coordinate contrasting pro- and anti-tumour responses in cancer and non-cancer (e.g. immune, stromal) cells. Considering the importance of inflammasomes to the net output of innate immune responses, here we provide an overview and discuss recent advancements on the diverse role of inflammasomes in cancer that have underpinned their potential targeting in diverse malignancies.

Activation of the helper NRC4 immune receptor forms a hexameric resistosome

Innate immune responses to microbial pathogens are regulated by intracellular receptors known as nucleotide-binding leucine-rich repeat receptors (NLRs) in both the plant and animal kingdoms. Across plant innate immune systems, "helper" NLRs (hNLRs) work in coordination with "sensor" NLRs (sNLRs) to modulate disease resistance signaling pathways. Activation mechanisms of hNLRs based on structures are unknown. Our research reveals that the hNLR, known as NLR required for cell death 4 (NRC4), assembles into a hexameric resistosome upon activation by the sNLR Bs2 and the pathogenic effector AvrBs2. This conformational change triggers immune responses by facilitating the influx of calcium ions (Ca2+) into the cytosol. The activation mimic alleles of NRC2, NRC3, or NRC4 alone did not induce Ca2+ influx and cell death in animal cells, suggesting that unknown plant-specific factors regulate NRCs' activation in plants. These findings significantly advance our understanding of the regulatory mechanisms governing plant immune responses.