The NLRP3 inflammasome: molecular activation and regulation to therapeutics

Identification and Validation of PKR as a Direct Target for the Novel Sulfonamide-Substituted Tetrahydroquinoline Nonselective Inhibitor of the NLRP3 Inflammasome

The NLRP3 inflammasome is a critical component of the innate immune system. The persistent abnormal activation of the NLRP3 inflammasome is implicated in numerous human diseases. Herein, sulfonamide-substituted tetrahydroquinoline derivative S-9 was identified as the most promising NLRP3 inhibitor, without obvious cytotoxicity. In vitro, S-9 inhibited the priming and activation stages of the NLRP3 inflammasome. Incidentally, we also observed that S-9 had inhibitory effects on the NLRC4 and AIM2 inflammasomes. To elucidate the multiple anti-inflammatory activities of S-9, photoaffinity probe P-2, which contained a photoaffinity label and a functional handle, was developed for target identification by chemical proteomics. We identified PKR as a novel target of S-9 in addition to NLRP3 by target fishing. Furthermore, S-9 exhibited a significant anti-neuroinflammatory effect in vivo. In summary, our findings show that S-9 is a promising lead compound targeting both PKR and NLRP3 that could emerge as a molecular tool for treating inflammasome-related diseases.

The Role of the Nrf2 Pathway in Airway Tissue Damage Due to Viral Respiratory Infections

Respiratory viruses constitute a significant cause of illness and death worldwide. Respiratory virus-associated injuries include oxidative stress, ferroptosis, inflammation, pyroptosis, apoptosis, fibrosis, autoimmunity, and vascular injury. Several studies have demonstrated the involvement of the nuclear factor erythroid 2-related factor 2 (Nrf2) in the pathophysiology of viral infection and associated complications. It has thus emerged as a pivotal player in cellular defense mechanisms against such damage. Here, we discuss the impact of Nrf2 activation on airway injuries induced by respiratory viruses, including viruses, coronaviruses, rhinoviruses, and respiratory syncytial viruses. The inhibition or deregulation of Nrf2 pathway activation induces airway tissue damage in the presence of viral respiratory infections. In contrast, Nrf2 pathway activation demonstrates protection against tissue and organ injuries. Clinical trials involving Nrf2 agonists are needed to define the effect of Nrf2 therapeutics on airway tissues and organs damaged by viral respiratory infections.

Immunoregulatory role of platelet derivatives in the macrophage-mediated immune response

Background

Macrophages are innate immune cells that display remarkable phenotypic heterogeneity and functional plasticity. Due to their involvement in the pathogenesis of several human conditions, macrophages are considered to be an attractive therapeutic target. In line with this, platelet derivatives have been successfully applied in many medical fields and as active participants in innate immunity, cooperation between platelets and macrophages is essential. In this context, the aim of this review is to compile the current evidence regarding the effects of platelet derivatives on the phenotype and functions of macrophages to identify the advantages and shortcomings for feasible future clinical applications.

Methods

A total of 669 articles were identified during the systematic literature search performed in PubMed and Web of Science databases.

Results

A total of 27 articles met the inclusion criteria. Based on published findings, platelet derivatives may play an important role in inducing a dynamic M1/M2 balance and promoting a timely M1-M2 shift. However, the differences in procedures regarding platelet derivatives and macrophages polarization and the occasional lack of information, makes reproducibility and comparison of results extremely challenging. Furthermore, understanding the differences between human macrophages and those derived from animal models, and taking into account the peculiarities of tissue resident macrophages and their ontogeny seem essential for the design of new therapeutic strategies.

Conclusion

Research on the combination of macrophages and platelet derivatives provides relevant information on the function and mechanisms of the immune response.

The vaginal immunoproteome for the prediction of spontaneous preterm birth: A retrospective longitudinal study

Background

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Most cases of preterm birth occur spontaneously and result from preterm labor with intact (spontaneous preterm labor [sPTL]) or ruptured (preterm prelabor rupture of membranes [PPROM]) membranes. The prediction of spontaneous preterm birth (sPTB) remains underpowered due to its syndromic nature and the dearth of independent analyses of the vaginal host immune response. Thus, we conducted the largest longitudinal investigation targeting vaginal immune mediators, referred to herein as the immunoproteome, in a population at high risk for sPTB.

Methods

Vaginal swabs were collected across gestation from pregnant women who ultimately underwent term birth, sPTL, or PPROM. Cytokines, chemokines, growth factors, and antimicrobial peptides in the samples were quantified via specific and sensitive immunoassays. Predictive models were constructed from immune mediator concentrations.

Results

Throughout uncomplicated gestation, the vaginal immunoproteome harbors a cytokine network with a homeostatic profile. Yet, the vaginal immunoproteome is skewed toward a pro-inflammatory state in pregnant women who ultimately experience sPTL and PPROM. Such an inflammatory profile includes increased monocyte chemoattractants, cytokines indicative of macrophage and T-cell activation, and reduced antimicrobial proteins/peptides. The vaginal immunoproteome has improved predictive value over maternal characteristics alone for identifying women at risk for early (<34 weeks) sPTB.

Conclusions

The vaginal immunoproteome undergoes homeostatic changes throughout gestation and deviations from this shift are associated with sPTB. Furthermore, the vaginal immunoproteome can be leveraged as a potential biomarker for early sPTB, a subset of sPTB associated with extremely adverse neonatal outcomes.

Funding

This research was conducted by the Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services (NICHD/NIH/DHHS) under contract HHSN275201300006C. ALT, KRT, and NGL were supported by the Wayne State University Perinatal Initiative in Maternal, Perinatal and Child Health.

Swaying the advantage: multifaceted functions of inflammasomes in adaptive immunity

Eukaryotic cells are equipped with cytoplasmic sensors that recognize diverse pathogen- or danger-associated molecular patterns. In cells of the myeloid lineage, activation of these sensors leads to the assembly of a multimeric protein complex, called the inflammasome, that culminates in the production of inflammatory cytokines and pyroptosis. Recently, investigation of the inflammasomes in lymphocytes led to the discovery of functional pathways that were initially believed to be confined to the innate arm of the immune system. Thus, the adapter protein apoptosis-associated speck-like protein containing a CARD (ASC) was documented to play a critical role in antigen uptake by dendritic cells, and regulation of T- and B-cell motility at several stages, and absent in melanoma 2 (AIM2) was found to act as a modulator of regulatory T-cell differentiation. Remarkably, NLRP3 was demonstrated to act as a transcription factor that controls Th2 cell polarization, and as a negative regulator of regulatory T-cell differentiation by limiting Foxp3 expression. In B lymphocytes, NLRP3 plays a role in the transcriptional network that regulates B-cell development and homing, and its activation is essential for germinal center formation and maturation of high-affinity antibody responses. Such recently discovered inflammasome-mediated functions in T and B lymphocytes offer multiple cross-talk opportunities for the innate and adaptive arms of the immune system. A better understanding of the dialog between inflammasomes and intracellular components could be beneficial for therapeutic purposes in restoring immune homeostasis and mitigating inflammation in a wide range of disorders.

Tmem30a protects against podocyte injury through suppression of pyroptosis

Podocytopathies, such as focal segmental glomerulosclerosis (FSGS), are characterized by podocyte injury and can easily progress to end-stage kidney disease. However, the mechanisms underlying podocyte injury remain unclear. We observed podocyte injury along with pyroptosis in patients with FSGS. Bioinformatic analysis of public datasets revealed that transmembrane protein 30a (Tmem30a) might be associated with FSGS. The expression of Temem30a and the podocyte-related protein, nephrin, were significantly downregulated in patients with FSGS, adriamycin (ADR)-induced mice, and podocyte-specific Tmem30a lox P /loxP ; NPHS2-Cre mice, whereas the expression of NLR family pyrin domain containing 3 (NLRP3) and ASC, two pyroptosis-related proteins, were significantly upregulated. Meanwhile, the pyroptosis inhibitor MCC950 and disulfiram (DSF) increased Tmem30a and podocyte-related proteins expression, and inhibited pyroptosis-related proteins expression in ADR-induced mouse podocytes and Tmem30a knockdown (KD) mouse podocytes. Therefore, Tmem30a might protect against podocyte injury by inhibiting pyroptosis, suggesting a potential therapeutic target for podocytopathies.

Underlying Mechanism of Lysosomal Membrane Permeabilization in CNS Injury: A Literature Review

Lysosomes play a crucial role in various intracellular pathways as their final destination. Various stressors, whether mild or severe, can induce lysosomal membrane permeabilization (LMP), resulting in the release of lysosomal enzymes into the cytoplasm. LMP not only plays a pivotal role in various cellular events but also significantly contributes to programmed cell death (PCD). Previous research has demonstrated the participation of LMP in central nervous system (CNS) injuries, including traumatic brain injury (TBI), spinal cord injury (SCI), subarachnoid hemorrhage (SAH), and hypoxic-ischemic encephalopathy (HIE). However, the mechanisms underlying LMP in CNS injuries are poorly understood. The occurrence of LMP leads to the activation of inflammatory pathways, increased levels of oxidative stress, and PCD. Herein, we present a comprehensive overview of the latest findings regarding LMP and highlight its functions in cellular events and PCDs (lysosome-dependent cell death, apoptosis, pyroptosis, ferroptosis, and autophagy). In addition, we consolidate the most recent insights into LMP in CNS injury by summarizing and exploring the latest advances. We also review potential therapeutic strategies that aim to preserve LMP or inhibit the release of enzymes from lysosomes to alleviate the consequences of LMP in CNS injury. A better understanding of the role that LMP plays in CNS injury may facilitate the development of strategic treatment options for CNS injury.

Inhibition of NLRP3 inflammasome activation by A20 through modulation of NEK7

The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.

Asprosin promotes vascular inflammation via TLR4-NFκB-mediated NLRP3 inflammasome activation in hypertension

Objective

and design Mild vascular inflammation promotes the pathogenesis of hypertension. Asprosin, a newly discovered adipokine, is closely associated with metabolic diseases. We hypothesized that asprosin might led to vascular inflammation in hypertension via NLRP3 inflammasome formation. This study shows the importance of asprosin in the vascular inflammation of hypertension.

Methods

Primary vascular smooth muscle cells (VSMCs) were obtained from the aorta of animals, including spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY), NLRP3-/- and wild-type mice. Studies were performed in VSMCs in vitro, as well as WKY and SHR in vivo.

Results

Asprosin expressions were up-regulated in VSMCs and media of arteries in SHR. Asprosin overexpression promoted NLRP3 inflammasome activation via Toll-like receptor 4 (TLR4), accompanied with activation of NFκB signaling pathway in VSMCs. Exogenous asprosin protein showed similar roles in promoting NLRP3 inflammasome activation. Knockdown of asprosin restrained NLRP3 inflammasome and p65-NFκB activation in VSMCs of SHR. NLRP3 inhibitor MCC950 or NFκB inhibitor BAY11-7082 attenuated asprosin-caused VSMC proliferation and migration. Asprosin-induced interleukin-1β production, proliferation and migration were attenuated in NLRP3-/- VSMCs. Local asprosin knockdown in common carotid artery of SHR attenuated inflammation and vascular remodeling.

Conclusions

Asprosin promoted NLRP3 inflammasome activation in VSMCs by TLR4-NFκB pathway, and thereby stimulates VSMCs proliferation, migration, and vascular remodeling of SHR.

Pyroptosis in Diabetic Peripheral Neuropathy and its Therapeutic Regulation

Pyroptosis is a pro-inflammatory form of cell death resulting from the activation of gasdermins (GSDMs) pore-forming proteins and the release of several pro-inflammatory factors. However, inflammasomes are the intracellular protein complexes that cleave gasdermin D (GSDMD), leading to the formation of robust cell membrane pores and the initiation of pyroptosis. Inflammasome activation and gasdermin-mediated membrane pore formation are the important intrinsic processes in the classical pyroptotic signaling pathway. Overactivation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome triggers pyroptosis and amplifies inflammation. Current evidence suggests that the overactivation of inflammasomes and pyroptosis may further induce the progression of cancers, nerve injury, inflammatory disorders and metabolic dysfunctions. Current evidence also indicates that pyroptosis-dependent cell death accelerates the progression of diabetes and its frequent consequences including diabetic peripheral neuropathy (DPN). Pyroptosis-mediated inflammatory reaction further exacerbates DPN-mediated CNS injury. Accumulating evidence shows that several molecular signaling mechanisms trigger pyroptosis in insulin-producing cells, further leading to the development of DPN. Numerous studies have suggested that certain natural compounds or drugs may possess promising pharmacological properties by modulating inflammasomes and pyroptosis, thereby offering potential preventive and practical therapeutic approaches for the treatment and management of DPN. This review elaborates on the underlying molecular mechanisms of pyroptosis and explores possible therapeutic strategies for regulating pyroptosis-regulated cell death in the pharmacological treatment of DPN.

Acute Lung Injury and the NLRP3 Inflammasome

Acute lung injury (ALI) manifests through harm to the capillary endothelium and alveolar epithelial cells, arising from a multitude of factors, leading to scattered interstitial alterations, pulmonary edema, and subsequent acute hypoxic respiratory insufficiency. Acute lung injury (ALI), along with its more serious counterpart, acute respiratory distress syndrome (ARDS), carry a fatality rate that hovers around 30-40%. Its principal pathological characteristic lies in the unchecked inflammatory reaction. Currently, the main strategies for treating ALI are alleviation of inflammation and prevention of respiratory failure. Concerning the etiology of ALI, NLRP3 Inflammasome is essential to the body's innate immune response. The composition of this inflammasome complex includes NLRP3, the pyroptosis mediator ASC, and pro-caspase-1. Recent research has reported that the inflammatory response centered on NLRP3 inflammasomes plays a key part in inflammation in ALI, and may hence be a prospective candidate for therapeutic intervention. In the review, we present an overview of the ailment characteristics of acute lung injury along with the constitution and operation of the NLRP3 inflammasome within this framework. We also explore therapeutic strategies targeting the NLRP3 inflammasome to combat acute lung injury.

Pyroptosis: A spoiler of peaceful coexistence between cells in degenerative bone and joint diseases

BACKGROUND

As people age, degenerative bone and joint diseases (DBJDs) become more prevalent. When middle-aged and elderly people are diagnosed with one or more disorders such as osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), it often signals the onset of prolonged pain and reduced functionality. Chronic inflammation has been identified as the underlying cause of various degenerative diseases, including DBJDs. Recently, excessive activation of pyroptosis, a form of programed cell death (PCD) mediated by inflammasomes, has emerged as a primary driver of harmful chronic inflammation. Consequently, pyroptosis has become a potential target for preventing and treating DBJDs.

AIM OF REVIEW

This review explored the physiological and pathological roles of the pyroptosis pathway in bone and joint development and its relation to DBJDs. Meanwhile, it elaborated the molecular mechanisms of pyroptosis within individual cell types in the bone marrow and joints, as well as the interplay among different cell types in the context of DBJDs. Furthermore, this review presented the latest compelling evidence supporting the idea of regulating the pyroptosis pathway for DBJDs treatment, and discussed the potential, limitations, and challenges of various therapeutic strategies involving pyroptosis regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In summary, an interesting identity for the unregulated pyroptosis pathway in the context of DBJDs was proposed in this review, which was undertaken as a spoiler of peaceful coexistence between cells in a degenerative environment. Over the extended course of DBJDs, pyroptosis pathway perpetuated its activity through crosstalk among pyroptosis cascades in different cell types, thus exacerbating the inflammatory environment throughout the entire bone marrow and joint degeneration environment. Correspondingly, pyroptosis regulation therapy emerged as a promising option for clinical treatment of DBJDs.

Role of NLRP3 inflammasome in nanoparticle adjuvant-mediated immune response

The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is pivotal in orchestrating the immune response induced by nanoparticle adjuvants. Understanding the intricate mechanisms underlying the activation of NLRP3 inflammasome by these adjuvants is crucial for deciphering their immunomodulatory properties. This review explores the involvement of the NLRP3 inflammasome in mediating immune responses triggered by nanoparticle adjuvants. It delves into the signaling pathways and cellular mechanisms involved in NLRP3 activation, highlighting its significance in modulating the efficacy and safety of nanoparticle-based adjuvants. A comprehensive grasp of the interplay between NLRP3 inflammasome and nanoparticle adjuvants holds promise for optimizing vaccine design and advancing immunotherapeutic strategies.

Inflammation in Fabry disease: stages, molecular pathways, and therapeutic implications

Fabry disease, a multisystem X-linked disorder caused by mutations in the alpha-galactosidase gene. This leads to the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (Lyso-Gb3), culminating in various clinical signs and symptoms that significantly impact quality of life. Although treatments such as enzyme replacement, oral chaperone, and emerging therapies like gene therapy exist; delayed diagnosis often curtails their effectiveness. Our review highlights the importance of delineating the stages of inflammation in Fabry disease to enhance the timing and efficacy of diagnosis and interventions, particularly before the progression to fibrosis, where treatment options are less effective. Inflammation is emerging as an important aspect of the pathogenesis of Fabry disease. This is thought to be predominantly mediated by the innate immune response, with growing evidence pointing towards the potential involvement of adaptive immune mechanisms that remain poorly understood. Highlighted by the fact that Fabry disease shares immune profiles with systemic autoinflammatory diseases, blurring the distinctions between these disorders and highlighting the need for a nuanced understanding of immune dynamics. This insight is crucial for developing targeted therapies and improving the administration of current treatments like enzyme replacement. Moreover, our review discusses the complex interplay between these inflammatory processes and current treatments, such as the challenges posed by anti-drug antibodies. These antibodies can attenuate the effectiveness of therapies, necessitating more refined approaches to mitigate their impact. By advancing our understanding of the molecular changes, inflammatory mediators and causative factors that drive inflammation in Fabry disease, we aim to clarify their role in the disease's progression. This improved understanding will help us see how these processes fit into the current landscape of Fabry disease. Additionally, it will guide the development of more effective diagnostic and therapeutic approaches, ultimately improving patient care.

Highly Effective Nobiletin-MPN in Yeast Microcapsules for Targeted Modulation of Oxidative Stress, NLRP3 Inflammasome Activation, and Immune Responses in Ulcerative Colitis

Inflammatory bowel disease (IBD) etiology is intricately linked to oxidative stress and inflammasome activation. Natural antioxidant nobiletin (NOB) contains excellent anti-inflammatory properties in alleviating intestinal injury. However, the insufficient water solubility and low bioavailability restrict its oral intervention for IBD. Herein, we constructed a highly efficient NOB-loaded yeast microcapsule (YM, NEFY) exhibiting marked therapeutic efficacy for dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) at a low oral dose of NOB (20 mg/kg). We utilized the metal polyphenol network (MPN) formed by self-assembly of epigallocatechin gallate (EGCG) and FeCl3 as the intermediate carrier to improve the encapsulation efficiency (EE) of NOB by 4.2 times. These microcapsules effectively alleviated the inflammatory reaction and oxidative stress of RAW264.7 macrophages induced by lipopolysaccharide (LPS). In vivo, NEFY with biocompatibility enabled the intestinal enrichment of NOB through controlled gastrointestinal release and macrophage targeting. In addition, NEFY could inhibit NLRP3 inflammasome and balance the macrophage polarization, which favors the complete intestinal mucosal barrier and recovery of colitis. Based on the oral targeted delivery platform of YM, this work proposes a novel strategy for developing and utilizing the natural flavone NOB to intervene in intestinal inflammation-related diseases.

Regulated cell death in hypoxic-ischaemic encephalopathy: recent development and mechanistic overview

Hypoxic-ischaemic encephalopathy (HIE) in termed infants remains a significant cause of morbidity and mortality worldwide despite the introduction of therapeutic hypothermia. Depending on the cell type, cellular context, metabolic predisposition and insult severity, cell death in the injured immature brain can be highly heterogenous. A continuum of cell death exists in the H/I-injured immature brain. Aside from apoptosis, emerging evidence supports the pathological activation of necroptosis, pyroptosis and ferroptosis as alternative regulated cell death (RCD) in HIE to trigger neuroinflammation and metabolic disturbances in addition to cell loss. Upregulation of autophagy and mitophagy in HIE represents an intrinsic neuroprotective strategy. Molecular crosstalk between RCD pathways implies one RCD mechanism may compensate for the loss of function of another. Moreover, mitochondrion was identified as the signalling "hub" where different RCD pathways converge. The highly-orchestrated nature of RCD makes them promising therapeutic targets. Better understanding of RCD mechanisms and crosstalk between RCD subtypes likely shed light on novel therapy development for HIE. The identification of a potential RCD converging node may open up the opportunity for simultaneous and synergistic inhibition of cell death in the immature brain.

ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 β (IL-1β) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1β production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.

Elevated NLRP3 Inflammasome Activation Is Associated with Motor Neuron Degeneration in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron degeneration in the central nervous system. Recent research has increasingly linked the activation of nucleotide oligomerization domain-like receptor protein 3 (NLRP3) inflammasome to ALS pathogenesis. NLRP3 activation triggers Caspase 1 (CASP 1) auto-activation, leading to the cleavage of Gasdermin D (GSDMD) and pore formation on the cellular membrane. This process facilitates cytokine secretion and ultimately results in pyroptotic cell death, highlighting the complex interplay of inflammation and neurodegeneration in ALS. This study aimed to characterize the NLRP3 inflammasome components and their colocalization with cellular markers using the wobbler mouse as an ALS animal model. Firstly, we checked the levels of miR-223-3p because of its association with NLRP3 inflammasome activity. The wobbler mice showed an increased expression of miR-223-3p in the ventral horn, spinal cord, and cerebellum tissues. Next, increased levels of NLRP3, pro-CASP 1, cleaved CASP 1 (c-CASP 1), full-length GSDMD, and cleaved GDSMD revealed NLRP3 inflammasome activation in wobbler spinal cords, but not in the cerebellum. Furthermore, we investigated the colocalization of the aforementioned proteins with neurons, microglia, and astrocyte markers in the spinal cord tissue. Evidently, the wobbler mice displayed microgliosis, astrogliosis, and motor neuron degeneration in this tissue. Additionally, we showed the upregulation of protein levels and the colocalization of NLRP3, c-CASP1, and GSDMD in neurons, as well as in microglia and astrocytes. Overall, this study demonstrated the involvement of NLRP3 inflammasome activation and pyroptotic cell death in the spinal cord tissue of wobbler mice, which could further exacerbate the motor neuron degeneration and neuroinflammation in this ALS mouse model.

Role of NLRP3 inflammasome in central nervous system diseases

The central nervous system (CNS) is the most delicate system in human body, with the most complex structure and function. It is vulnerable to trauma, infection, neurodegeneration and autoimmune diseases, and activates the immune system. An appropriate inflammatory response contributes to defence against invading microbes, whereas an excessive inflammatory response can aggravate tissue damage. The NLRP3 inflammasome was the first one studied in the brain. Once primed and activated, it completes the assembly of inflammasome (sensor NLRP3, adaptor ASC, and effector caspase-1), leading to caspase-1 activation and increased release of downstream inflammatory cytokines, as well as to pyroptosis. Cumulative studies have confirmed that NLRP3 plays an important role in regulating innate immunity and autoimmune diseases, and its inhibitors have shown good efficacy in animal models of various inflammatory diseases. In this review, we will briefly discuss the biological characteristics of NLRP3 inflammasome, summarize the recent advances and clinical impact of the NLRP3 inflammasome in infectious, inflammatory, immune, degenerative, genetic, and vascular diseases of CNS, and discuss the potential and challenges of NLRP3 as a therapeutic target for CNS diseases.

A Dynamic Protocol to Explore NLRP3 Inflammasome Activation in Cerebral Organoids

The NLRP3 inflammasome plays a crucial role in the inflammatory response, reacting to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). This response is essential for combating infections and restoring tissue homeostasis. However, chronic activation can lead to detrimental effects, particularly in neuropsychiatric and neurodegenerative diseases. Our study seeks to provide a method to effectively measure the NLRP3 inflammasome's activation within cerebral organoids (COs), providing insights into the underlying pathophysiology of these conditions and enabling future studies to investigate the development of targeted therapies.

The Complement System as a Therapeutic Target in Retinal Disease

The complement cascade is a vital system in the human body's defense against pathogens. During the natural aging process, it has been observed that this system is imperative for ensuring the integrity and homeostasis of the retina. While this system is critical for proper host defense and retinal integrity, it has also been found that dysregulation of this system may lead to certain retinal pathologies, including geographic atrophy and diabetic retinopathy. Targeting components of the complement system for retinal diseases has been an area of interest, and in vivo, ex vivo, and clinical trials have been conducted in this area. Following clinical trials, medications targeting the complement system for retinal disease have also become available. In this manuscript, we discuss the pathophysiology of complement dysfunction in the retina and specific pathologies. We then describe the results of cellular, animal, and clinical studies targeting the complement system for retinal diseases. We then provide an overview of complement inhibitors that have been approved by the Food and Drug Administration (FDA) for geographic atrophy. The complement system in retinal diseases continues to serve as an emerging therapeutic target, and further research in this field will provide additional insights into the mechanisms and considerations for treatment of retinal pathologies.

Estrogen receptor β activation alleviates inflammatory bowel disease by suppressing NLRP3-dependent IL-1β production in macrophages via downregulation of intracellular calcium level

INTRODUCTION

Although several estrogen receptor β (ERβ) agonists have been reported to alleviate IBD, the pivotal mechanism remains obscure.

OBJECTIVES

To examine the effects and mechanisms of ERβ activation on cytokine/chemokine networks in colitis mice.

METHODS

Dextran sulfate sodium salt (DSS) and trinitro-benzene-sulfonic acid (TNBS) were used to induce mouse colitis model. Multiple molecular biological methods were employed to evaluate the severity of mouse colitis and the level of cytokine and/or chemokine.

RESULTS

Bioinformatics analysis, ELISA and immunofluorescence results showed that the targeted cytokines and/or chemokines associated with ERβ expression and activation is IL-1β, and the anti-colitis effect of ERβ activation was significantly attenuated by the overexpression of AAV9-IL-1β. Immunofluorescence analysis indicated that ERβ activation led to most evident downregulation of IL-1β expression in colonic macrophages as compared to monocytes and neutrophils. Given the pivotal roles of NLRP3, NLRC4, and AIM2 inflammasome activation in the production of IL-1β, we examined the influence of ERβ activation on inflammasome activity. ELISA and WB results showed that ERβ activation selectively blocked the NLRP3 inflammasome assembly-mediated IL-1β secretion. The calcium-sensing receptor (CaSR) and calcium signaling play crucial roles in the assembly of the NLRP3 inflammasome. WB and immunofluorescence results showed that ERβ activation reduced intracellular CaSR expression and calcium signaling in colonic macrophages. Combination with CaSR overexpression plasmid reversed the suppressive effect of ERβ activation on NLRP3 inflammasome assembly, and counteracting the downregulation of IL-1β secretion.

CONCLUSION

Our research uncovers that the anti-colitis effect of ERβ activation is accomplished through the reduction of IL-1β levels in colonic tissue, achieved by specifically decreasing CaSR expression in macrophages to lower intracellular calcium levels and inhibit NLRP3 inflammasome assembly-mediated IL-1β production.

Intrathecal gastrodin alleviates allodynia in a rat spinal nerve ligation model through NLRP3 inflammasome inhibition

BACKGROUND

Gastrodin (GAS), a main bioactive component of the herbal plant, Gastrodia elata Blume, has shown to have beneficial effects on neuroinflammatory diseases such as Alzheimer's disease in animal studies and migraine in clinical studies. Inflammasome is a multimeric protein complex having a core of pattern recognition receptor and has been implicated in the development of neuroinflammatory diseases. Gastrodin has shown to modulate the activation of nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome. This study investigated the effects of GAS on the intensity of mechanical allodynia and associated changes in NLRP3 inflammasome expression at the spinal level using L5/6 spinal nerve ligation model (SNL) in rats.

METHODS

Intrathecal (IT) catheter implantation and SNL were used for drug administration and pain model in male Sprague-Dawley rats. The effect of gastrodin or MCC950 (NLRP3 inflammasome inhibitor) on mechanical allodynia was measured by von Frey test. Changes in NLRP3 inflammasome components and interleukin-1β (IL-1β) and cellular expression were examined in the spinal cord and dorsal root ganglion.

RESULTS

The expression of NLRP3 inflammasome components was found mostly in the neurons in the spinal cord and dorsal root ganglion. The protein and mRNA levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, and IL-1β were upregulated in SNL animals compared to Sham animals. IT administration of GAS significantly attenuated the expression of NLRP3 inflammasome and the intensity of SNL-induced mechanical allodynia. NLRP3 inflammasome inhibitor, MCC950, also attenuated the intensity of allodynia, but the effect is less strong and shorter than that of GAS.

CONCLUSIONS

Expression of NLRP3 inflammasome and IL-1β is greatly increased and mostly found in the neurons at the spinal level in SNL model, and IT gastrodin exerts a significant anti-allodynic effect in SNL model partly through suppressing the expression of NLRP3 inflammasome.

TBHQ Alleviates Particulate Matter-Induced Pyroptosis in Human Nasal Epithelial Cells

Pyroptosis represents a type of cell death mechanism notable for its cell membrane disruption and the subsequent release of proinflammatory cytokines. The Nod-like receptor family pyrin domain containing inflammasome 3 (NLRP3) plays a critical role in the pyroptosis mechanism associated with various diseases resulting from particulate matter (PM) exposure. Tert-butylhydroquinone (tBHQ) is a synthetic antioxidant commonly used in a variety of foods and products. The aim of this study is to examine the potential of tBHQ as a therapeutic agent for managing sinonasal diseases induced by PM exposure. The occurrence of NLRP3 inflammasome-dependent pyroptosis in RPMI 2650 cells treated with PM < 4 µm in size was confirmed using Western blot analysis and enzyme-linked immunosorbent assay results for the pyroptosis metabolites IL-1β and IL-18. In addition, the inhibitory effect of tBHQ on PM-induced pyroptosis was confirmed using Western blot and immunofluorescence techniques. The inhibition of tBHQ-mediated pyroptosis was abolished upon nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown, indicating its involvement in the antioxidant mechanism. tBHQ showed potential as a therapeutic agent for sinonasal diseases induced by PM because NLRP3 inflammasome activation was effectively suppressed via the Nrf2 pathway.

Exosomal HMGB3 released by glioma cells confers the activation of NLRP3 inflammasome and pyroptosis in tumor-associated macrophages

BACKGROUND

Previous evidences has highlighted the pivotal role of NOD-like receptor family pyrin domain-containing 3 (NLRP3)-mediated inflammasomes and pyroptosis activation in driving tumor malignancy and shaping the tumor microenvironment. Herein, we aimed to elucidate the impact of high-mobility group box 3 (HMGB3) released in glioma-derived exosomes on macrophage infiltration in gliomas, NLRP3 inflammasome activation and polarization.

METHODS

Transcripts and protein levels of HMGB3, and cytokines associated with macrophage phenotypes and pyroptosis were assessed in glioma tissues and cell lines (U251, LN229, T98G, A172) using qRT-PCR and/or Western blot analysis. Exosomes secreted from LN229 and NHA cells were isolated via differential ultracentrifugation and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and analysis of exosome-related markers. PKH67 staining was employed to examine exosomes uptake by THP-1 differentiated macrophages. Flow cytometry was utilized to assess macrophage pyroptotic rates and polarization-related markers.

RESULTS

HMGB3 expression was elevated in glioma tissues, serum samples and tumor cell lines. Kaplan-Meier curves revealed a positive correlation between higher HMGB3 expression and poor overall survival and recurrence-free survival. Moreover, glioma tissues with increased HMGB3 expression exhibited significant upregulation of M2 macrophages markers (CD68, CD206, Arg1) and NLRP3 inflammasome components (NLRP3, IL-1β, ASC), suggesting that HMGB3 was closely associated with macrophage infiltration and NLRP3 inflammasome activation. Notably, HMGB3 was found to be enriched in glioma cell- secreted exosomes and could be internalized by macrophages. Knockdown of HMGB3 in glioma cell exosomes could restrain M2 macrophage polarization, NLRP3 inflammasome activation and pyroptosis.

CONCLUSION

These findings suggested that glioma cells secreted exosomal HMGB3 could facilitate macrophage M2 polarization, pyroptosis and inflammatory infiltration, indicating HMGB3 might be a poor prognosis factor for glioma.

Activation of NLRP3 inflammasome in a rat model of cerebral small vessel disease

Cerebral small vessel disease (CSVD) is increasingly being recognized as a leading contributor to cognitive impairment in the elderly. However, there is a lack of effective preventative or therapeutic options for CSVD. In this exploratory study, we investigated the interplay between neuroinflammation and CSVD pathogenesis as well as the cognitive performance, focusing on NLRP3 signaling as a new therapeutic target. Spontaneously hypertensive stroke-prone (SHRSP) rats served as a CSVD model. We found that SHRSP rats showed decline in learning and memory abilities using morris water maze test. Activated NLRP3 signaling and an increased expression of the downstream pro-inflammatory factors, including IL (interleukin)-6 and tumor necrosis factor α were determined. We also observed a remarkable increase in the production of pyroptosis executive protein gasdermin D, and elevated astrocytic and microglial activation. In addition, we identify several neuropathological hallmarks of CSVD, including blood-brain barrier breakdown, white matter damage, and endothelial dysfunction. These results were in correlation with the activation of NLRP3 inflammasome. Thus, our findings reveal that the NLRP3-mediated inflammatory pathway could play a central role in the pathogenesis of CSVD, presenting a novel target for potential CSVD treatment.

Ficolin-A/2 Aggravates Severe Lung Injury through Neutrophil Extracellular Traps Mediated by Gasdermin D-Induced Pyroptosis

Neutrophil extracellular traps (NETs) and pyroptosis are critical events in lung injury. This study investigated whether ficolin-A influenced NET formation through pyroptosis to exacerbate lipopolysaccharide (LPS)-induced lung injury. The expression of ficolin-A/2, NETs, and pyroptosis-related molecules was investigated in animal and cell models. Knockout and knockdown (recombinant protein) methods were used to elucidate regulatory mechanisms. The Pearson correlation coefficient was used to analyze the correlation between ficolins and pyroptosis- and NET-related markers in clinical samples. In this study, ficolin-2 (similar to ficolin-A) showed significant overexpression in patients with acute respiratory distress syndrome. In vivo, knockout of Fcna, but not Fcnb, attenuated lung inflammation and inhibited NET formation in the LPS-induced mouse model. DNase I further alleviated lung inflammation and NET formation in Fcna knockout mice. In vitro, neutrophils derived from Fcna-/- mice showed less pyroptosis and necroptosis than those from the control group after LPS stimulation. Additionally, GSDMD knockdown or Nod-like receptor protein 3 inhibitor reduced NET formation. Addition of recombinant ficolin-2 protein to human peripheral blood neutrophils promoted NET formation and pyroptosis after LPS stimulation, whereas Fcn2 knockdown had the opposite effect. Acute respiratory distress syndrome patients showed increased levels of pyroptosis- and NET-related markers, which were correlated positively with ficolin-2 levels. In conclusion, these results suggested that ficolin-A/2 exacerbated NET formation and LPS-induced lung injury via gasdermin D-mediated pyroptosis.

Paeoniflorin alleviates depression by inhibiting the activation of NLRP3 inflammasome via promoting mitochondrial autophagy

Depression ranks among the most common neuropsychiatric disorders globally. Current studies examining the roles of inflammation and mitochondrial autophagy in the antidepressant efficacy of paeoniflorin (PF) are sparse. This study aimed to elucidate PF's antidepressant mechanism by promoting autophagy and inhibiting NLRP3 inflammasome activation using chronic unpredictable mild stimulation (CUMS)-induced C57BL/6 mouse models in vivo and corticosterone (CORT)-induced HT22 cell models in vitro. Results demonstrated that PF enhanced the viability of HT22 cells following CORT exposure, restored mitochondrial membrane potential (MMP), reduced reactive oxygen species accumulation, increased LC3 fluorescence intensity, and suppressed inflammatory cytokine secretion and inflammation activation. Additionally, PF ameliorated depressive behaviors induced by CUMS and improved damage in hippocampal neurons. It also reduced the expression of NLRP3, ASC, Caspase-1, IL-1β, and the assembly of the NLRP3 inflammasome. Moreover, PF upregulated the expression of autophagy-related proteins in the hippocampus, facilitating the clearance of damaged mitochondria and enhancing autophagy. The role of autophagy in PF's antidepressant effects was further confirmed through the use of the autophagy inhibitor 3-methyladenine (3-MA), which reduced the efficacy of PF. In conclusion, PF effectively improved depressive behaviors in CUMS-induced mice and reduced NLRP3-mediated inflammation both in vivo and in vitro, likely via the induction of autophagy.

Pyroptosis of Vascular Smooth Muscle Cells as a Potential New Target for Preventing Vascular Diseases

Vascular remodeling is the adaptive response of the vessel wall to physiological and pathophysiological changes, closely linked to vascular diseases. Vascular smooth muscle cells (VSMCs) play a crucial role in this process. Pyroptosis, a form of programmed cell death characterized by excessive release of inflammatory factors, can cause phenotypic transformation of VSMCs, leading to their proliferation, migration, and calcification-all of which accelerate vascular remodeling. Inhibition of VSMC pyroptosis can delay this process. This review summarizes the impact of pyroptosis on VSMCs and the pathogenic role of VSMC pyroptosis in vascular remodeling. We also discuss inhibitors of key proteins in pyroptosis pathways and their effects on VSMC pyroptosis. These findings enhance our understanding of the pathogenesis of vascular remodeling and provide a foundation for the development of novel medications that target the control of VSMC pyroptosis as a potential treatment strategy for vascular diseases.

Pharmacological evaluation of newly synthesized benzimidazole derivative for anti-Alzheimer potential

Backgound: Alzheimer disease (AD) is a disastrous disease characterized by accretion of amyloid-beta plaques, neurofibrillary tangles inducing oxidative stress, loss of neuronal functions and continuous progression of cognitive impairment leading to severe dementia.

Material and Methods: The newly synthesized benzimidazole derivative 4-chloro-3-(2-phenyl-1H-benzimidazole-1-sulfonyl) benzoic acid (CB) was evaluated for its anti-Alzheimer activity using in silico, in vivo, in vitro and molecular techniques (ELISA, WB & IHC).

Results: In-silico studies revealed that CB has atomic contact energy values of -3.9 to -8.9 kcal/mol against selected targets. In vitro assay showed that CB caused acetylcholinesterase (AChE) and diphenyl-1-picrylhydrazyl inhibition. In-vivo findings revealed improvement in dementia as observed in the morris water maze test and Ymaze test. Amyloid-beta disaggregation, increased level of anti-oxidants, decreased expressions of inflammatory markers and enhanced cellular architecture were found in the cortex and hippocampus of treated rats in the histopathological examination, immunohistochemistry analysis, enzyme-linked immunosorbent assay and western blot analysis.

Conclusions: This study revealed that CB possess different binding affinities with the Alzheimer-related targets and it possess anti-Alzheimer activity, mediated via AChE and amyloid-beta inhibition, anti-oxidant and anti-inflammatory pathways.

Gastrointestinal mucositis: a sign of a (systemic) inflammatory response

PURPOSE OF REVIEW

Gastrointestinal mucositis (GIM) is a significant complication of cancer therapy. Whilst inflammation is a central feature of GIM, studies attempting to mitigate mucosal damage via this mechanism are scarce. This review describes the relation between GIM, local and systemic inflammation, and the microbiome and its metabolites, and explores recent research on therapeutics that target this relationship.

RECENT FINDINGS

Recent literature underscores the pivotal role of inflammation in GIM, elucidating its bidirectional relation with disturbance of the gut microbiota composition and intestinal permeability. These events cause a heightened risk of bloodstream infections and lead to systemic inflammation. While studies investigating risk prediction models or therapeutics targeting GIM-related inflammation remain scarce, results have shown promise in finding biomarkers and alleviating GIM and its accompanying clinical symptoms.

SUMMARY

The findings underscore the important role of inflammation and the microbiome in GIM. Understanding the inflammatory pathways driving GIM is crucial for developing effective treatments. Further research is needed using genomics, epigenomics, and microbiomics to explore better risk prediction models or therapeutic strategies aimed at mitigating GIM-related inflammation.

ADP as a novel stimulus for NLRP3-inflammasome activation in mice fails to translate to humans

The NLRP3-inflammasome is a cytosolic multiprotein complex that triggers an inflammatory response to certain danger signals. Recently adenosine diphosphate (ADP) was found to activate the NLRP3-inflammasome in murine macrophages via the P2Y1 receptor. Blockade of this signaling pathway reduced disease severity in a murine colitis-model. However, the role of the ADP/P2Y1-axis has not yet been studied in humans. This present study confirmed ADP-dependent NLRP3-inflammasome activation in murine macrophages, but found no evidence for a role of ADP in inflammasome activation in humans. We investigated the THP1 cell line as well as primary monocytes and further looked at macrophages. Although all cells express the three human ADP-receptors P2Y1, P2Y12 and P2Y13, independent of priming, neither increased ASC-speck formation could be detected with flow cytometry nor additional IL-1β release be found in the culture supernatant of ADP stimulated cells. We now show for the first time that the responsiveness of monocytes and macrophages to ADP as well as the regulation of its purinergic receptors is very much dependent on the species. Therefore the signaling pathway found to contribute to colitis in mice is likely not applicable to humans.

GSNOR negatively regulates the NLRP3 inflammasome via S-nitrosation of MAPK14

Hyperactivation of the NLRP3 inflammasome has been implicated in the pathogenesis of numerous diseases. However, the precise molecular mechanisms that modulate the transcriptional regulation of NLRP3 remain largely unknown. In this study, we demonstrated that S-nitrosoglutathione reductase (GSNOR) deficiency in macrophages leads to significant increases in the Nlrp3 and Il-1β expression levels and interleukin-1β (IL-1β) secretion in response to NLRP3 inflammasome stimulation. Furthermore, in vivo experiments utilizing Gsnor-/- mice revealed increased disease severity in both lipopolysaccharide (LPS)-induced septic shock and dextran sodium sulfate (DSS)-induced colitis models. Additionally, we showed that both LPS-induced septic shock and DSS-induced colitis were ameliorated in Gsnor-/- Nlrp3-/- double-knockout (DKO) mice. Mechanistically, GSNOR deficiency increases the S-nitrosation of mitogen-activated protein kinase 14 (MAPK14) at the Cys211 residue and augments MAPK14 kinase activity, thereby promoting Nlrp3 and Il-1β transcription and stimulating NLRP3 inflammasome activity. Our findings suggested that GSNOR is a regulator of the NLRP3 inflammasome and that reducing the level of S-nitrosylated MAPK14 may constitute an effective strategy for alleviating diseases associated with NLRP3-mediated inflammation.

Pepsin-mediated inflammation in laryngopharyngeal reflux via the ROS/NLRP3/IL-1β signaling pathway

BACKGROUND

Laryngopharyngeal reflux (LPR) is one of the most common disorders in otorhinolaryngology, affecting up to 10% of outpatients visiting otolaryngology departments. In addition, 50% of hoarseness cases are related to LPR. Pepsin reflux-induced aseptic inflammation is a major trigger of LPR; however, the underlying mechanisms are unclear. The nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome has become an important bridge between stimulation and sterile inflammation and is activated by intracellular reactive oxygen species (ROS) in response to danger signals, leading to an inflammatory cascade. In this study, we aimed to determine whether pepsin causes LPR-associated inflammatory injury via mediating inflammasome activation and explore the potential mechanism.

METHODS

We evaluated NLRP3 inflammasome expression and ROS in the laryngeal mucosa using immunofluorescence and immunohistochemistry. Laryngeal epithelial cells were exposed to pepsin and analyzed using flow cytometry, western blotting, and real-time quantitative PCR to determine ROS, NLRP3, and pro-inflammatorycytokine levels.

RESULTS

Pepsin expression was positively correlated with ROS as well as caspase-1 and IL-1β levels in laryngeal tissues. Intracellular ROS levels were elevated by increased pepsin concentrations, which were attenuated by apocynin (APO)-a ROS inhibitor-in vitro. Furthermore, pepsin significantly induced the mRNA and protein expression of thioredoxin-interacting protein, NLRP3, caspase-1, and IL-1β in a dose-dependent manner. APO and the NLRP3 inhibitor, MCC950, inhibited NLRP3 inflammasome formation and suppressed laryngeal epithelial cell damage.

CONCLUSION

Our findings verified that pepsin could regulate the NLRP3/IL-1β signaling pathway through ROS activation and further induce inflammatory injury in LPR. Targeting the ROS/NLRP3 inflammasome signaling pathway may help treat patients with LPR disease.

IL-17 Control of Cutaneous Immune Homeostasis

IL-17 is widely recognized for its roles in host defense and inflammatory disorders. However, it has become clear that IL-17 is also an essential regulator of barrier tissue physiology. Steady-state microbe sensing at the skin surface induces low-level IL-17 expression that enhances epithelial integrity and resists pathogens without causing overt inflammation. Recent reports describe novel protective roles for IL-17 in wound healing and counteracting physiologic stress; however, chronic amplification of these beneficial responses contributes to skin pathologies as diverse as fibrosis, cancer, and autoinflammation. In this paper, we discuss the context-specific roles of IL-17 in skin health and disease and therapeutic opportunities.

The interplay between mitochondrial dysfunction and NLRP3 inflammasome in multiple sclerosis: Therapeutic implications and animal model studies

Multiple sclerosis (MS) is a complex autoimmune disorder that impacts the central nervous system (CNS), resulting in inflammation, demyelination, and neurodegeneration. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome, a multiprotein complex of the innate immune system, serves an essential role in the pathogenesis of MS by regulating the production of pro-inflammatory cytokines (IL-1β & IL-18) and the induction of pyroptotic cell death. Mitochondrial dysfunction is one of the main potential factors that can trigger NLRP3 inflammasome activation and lead to inflammation and axonal damage in MS. This highlights the importance of understanding how mitochondrial dynamics modulate NLRP3 inflammasome activity and contribute to the inflammatory and neurodegenerative features of MS. The lack of a comprehensive understanding of the pathogenesis of MS and the urge for the introduction of new therapeutic strategies led us to review the therapeutic potential of targeting the interplay between mitochondrial dysfunction and the NLRP3 inflammasome in MS. This paper also evaluates the natural and synthetic compounds that can improve mitochondrial function and/or inhibit the NLRP3 inflammasome, thereby providing neuroprotection. Moreover, it summarizes the evidence from animal models of MS that demonstrate the beneficial effects of these compounds on reducing inflammation, demyelination, and neurodegeneration. Finally, this review advocates for a deeper investigation into the molecular crosstalk between mitochondrial dynamics and the NLRP3 inflammasome as a means to refine therapeutic targets for MS.

Human pluripotent stem cell (hPSC)-derived microglia for the study of brain disorders. A comprehensive review of existing protocols

Microglia, resident immune cells of the brain that originate from the yolk sac, play a critical role in maintaining brain homeostasis by monitoring and phagocytosing pathogens and cellular debris in the central nervous system (CNS). While they share characteristics with myeloid cells, they are distinct from macrophages. In response to injury, microglia release pro-inflammatory factors and contribute to brain homeostasis through activities such as synapse pruning and neurogenesis. To better understand their role in neurological disorders, the generation of in vitro models of human microglia has become essential. These models, derived from patient-specific induced pluripotent stem cells (iPSCs), provide a controlled environment to study the molecular and cellular mechanisms underlying microglia-mediated neuroinflammation and neurodegeneration. The incorporation or generation of microglia into three-dimensional (3D) organoid cultures provides a more physiologically relevant environment that offers further opportunities to study microglial dynamics and disease modeling. This review describes several protocols that have been recently developed for the generation of human-induced microglia. Importantly, it highlights the promise of these in vitro models in advancing our understanding of brain disorders and facilitating personalized drug screening.

Polyunsaturated fatty acid-derived lipid mediator Resolvin D1 alleviates sepsis-induced disseminated intravascular coagulation via Caspase-1/Gasdermin D pyroptotic pathway

BACKGROUND & AIMS

Sepsis-induced disseminated intravascular coagulation (DIC) is characterised by abnormal blood clotting resulting from severe infection, contributing to organ dysfunction in sepsis. Resolvin D1 (RvD1) is an endogenous lipid mediator, synthesised from the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) through enzymatic processes involving 15-LOX and 5-LOX. RvD1 is recognised for its protective properties against various inflammatory conditions. This study aims to investigate its potential to modulate coagulation dysfunction in sepsis and to evaluate coagulation disorders in septic patients.

METHODS

Sepsis models were established by intraperitoneal injection LPS (20 mg/kg) or cecal ligation and puncture (CLP) followed by injection of RvD1 (10 μg/kg) or saline. The impact of RvD1 on coagulation dysfunction was assessed by clotting time and coagulation indicators such as TAT, D-dimer, PAI-1, and fibrinogen. The activity of the coagulation system in vivo was observed by evaluating dynamic microcirculation, platelets and thrombin in mice using intravital microscopy. The effect of RvD1 on pyroptosis was investigated by measuring NOD-like receptor protein 3 (NLRP3), Caspase-1, Caspase-11, and Gasdermin D (GSDMD) levels via western blot. Caspase-1 knockout mice, GSDMD knockout mice and bone marrow-derived macrophages (BMDMs) were used to elucidate the underlying mechanisms. Lastly, the concentration of RvD1 in plasma from septic patients was quantified to explore its relationship with coagulation and pyroptosis.

RESULTS

RvD1 significantly attenuated coagulation dysfunction in septic mice induced by LPS and CLP, and inhibited Caspase-1/GSDMD-dependent pyroptosis in septic mice and bone marrow-derived macrophages. In septic patients, the plasma concentrations of RvD1 was negatively correlated with both coagulation-related indicators and markers of GSDMD activation.

CONCLUSION

The results suggest that RvD1 can improve coagulation dysfunction in sepsis by regulating the Caspase-1/GSDMD pyroptotic pathway. Additionally, the concentration of RvD1 in septic patient plasma is related to prognosis and DIC development. RvD1 could be a potential biomarker and a promising therapeutic alternative in sepsis-induced DIC.

MDSC-targeting gold nanoparticles enhance PD-1 tumor immunotherapy by inhibiting NLRP3 inflammasomes

Myeloid-derived suppressor cells (MDSCs) play a crucial role in the immune escape mechanisms that limit the efficacy of immunotherapeutic strategies. In the tumor microenvironment, NLRP3 inflammasome-driven Interleukin-1β (IL-1β) production serves to dampen antitumor immune responses, promoting tumor growth, progression, and immunosuppression. In this study, we revealed that gold nanoparticles (Au NPs) with a size of 30 nm disrupted NLRP3 inflammasome, but not other inflammasomes, in bone marrow-derived macrophages through abrogating NLRP3-NEK7 interactions mediated by reactive oxygen species (ROS). Density functional theory (DFT) calculations provided insights into the mechanism underlying the exceptional ROS scavenging capabilities of Au NPs. Additionally, when coupled with H6, a small peptide targeting MDSCs, Au NPs demonstrated the capacity to effectively reduce IL-1β levels and diminish the MDSCs population in tumor microenvironment, leading to enhanced T cell activation and increased immunotherapeutic efficacy in mouse tumor models that are sensitive and resistant to PD-1 inhibition. Our findings unraveled a novel approach wherein peptide-modified Au NPs relieved the suppressive impact of the tumor microenvironment by inhibiting MDSCs-mediated IL-1β release, which is the first time reported the employing a nanostrategy at modulating MDSCs to reverse the immunosuppressive microenvironment and may hold promise as a potential therapeutic agent for cancer immunotherapy.

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Co-exposure of microcystin and nitrite enhanced spermatogenic disorders: The role of mtROS-mediated pyroptosis and apoptosis

Microcystins (MCs) and nitrites are coexisted in the environment and have reproductive toxicity. The combined toxic effect and mechanism of MCs and nitrite on spermatogenesis remain largely unclear. In the present study, co-exposure to microcystin-leucine arginine (MC-LR) and sodium nitrite (NaNO2) aggravated testicular damage of Balb/c mice and mitochondrial impairment of spermatogonia, Sertoli cells, and sperm. Furthermore, MC-LR and NaNO2 reduced sperm density with a synergistic effect. In addition, MC-LR and NaNO2 synergistically induced oxidative stress in the reproductive system by decreasing superoxide dismutase (SOD) activity and glutathione (GSH) levels and increasing levels of mitochondrial reactive oxygen species (mtROS) and reactive oxygen species (ROS). More importantly, mitoquidone mesylate (MitoQ), an inhibitor of mtROS, blocked MC-LR and NaNO2-induced spermatogonia and Sertoli cell apoptosis by inhibiting high expression of Bax, Fadd, Caspase-8, and cleaved-Caspase-3. On the other hand, MitoQ suppressed pyroptosis of Sertoli cells by inhibiting the expression of NLRP3, N-GSDMD, and cleaved-Caspase-1. Additionally, MitoQ alleviated co-exposure-induced sperm density reduction and organ index disorders in F1 generation mice. Together, co-exposure of MC-LR and NaNO2 can enhance spermatogenic disorders by mitochondrial oxidative impairment-mediated germ cell death. This study emphasizes the potential risks of MC-LR and NaNO2 on reproduction in realistic environments and highlights new insights into the cause and treatment of spermatogenic disorders.

Mechanisms and functions of protein S-acylation

Over the past two decades, protein S-acylation (often referred to as S-palmitoylation) has emerged as an important regulator of vital signalling pathways. S-Acylation is a reversible post-translational modification that involves the attachment of a fatty acid to a protein. Maintenance of the equilibrium between protein S-acylation and deacylation has demonstrated profound effects on various cellular processes, including innate immunity, inflammation, glucose metabolism and fat metabolism, as well as on brain and heart function. This Review provides an overview of current understanding of S-acylation and deacylation enzymes, their spatiotemporal regulation by sophisticated multilayered mechanisms, and their influence on protein function, cellular processes and physiological pathways. Furthermore, we examine how disruptions in protein S-acylation are associated with a broad spectrum of diseases from cancer to autoinflammatory disorders and neurological conditions.

Exosomes derived from mesenchymal stem cells attenuate NLRP3-related pyroptosis in autoimmune premature ovarian insufficiency via the NF-κB pathway

RESEARCH QUESTION

What is the effect of exosomes derived from bone marrow mesenchymal stem cells (MSC-Exos) on the pyroptosis and recovery of granulosa cells in autoimmune premature ovarian insufficiency (POI)?

DESIGN

In vitro, KGN cells were exposed to interferon-gamma to simulate immune injury. Samples were collected after a 48 h incubation with MSC-Exos (30 μg/ml). The cell viability, secretion of oestrogen and expression of key molecules in pyroptosis and the nuclear factor kappa B (NF-κB) pathway were tested. In vivo, the BALB/c mouse model of autoimmune POI model induced by zona pellucida glycoprotein 3 was used. Fertility testing and sample collection were applied 4 weeks after the ovarian subcapsular injection of MSC-Exos (150 μg for each ovary). Hormone concentration measurements, follicle counting and pyroptotic pathway analyses were conducted for each group.

RESULTS

In vitro, MSC-Exos significantly promoted the proliferation rate and secretion of oestrogen, while at the same time suppressing apoptosis and pyroptosis. In vivo, exosomal treatment normalized the irregular oestrous cycles, rescued the follicular loss and increased the pregnancy rate and number of offspring in POI mice. Elevated serum concentrations of oestrogen and anti-Müllerian hormone, as well as decreased concentrations of FSH and interleukin-1β, were shown. Furthermore, MSC-Exos down-regulated the expression of the NLRP3/Casp1/GSDMD pathway and inhibited activation of the NF-κB pathway.

CONCLUSIONS

These findings demonstrate for the first time that MSC-Exos exert a significant effect on restoring ovarian function in autoimmune POI in vivo and in vitro by suppressing the NLRP3/Casp1/GSDMD pathway and pyroptosis. The NF-κB pathway may contribute to the regulation of NLRP3-related pyroptosis.

Lack of Annexin A1 Exacerbates Inflammatory Response in Acute Endometritis Model

Annexin A1 (AnxA1) is a glucocorticoid-inducible protein and an important endogenous modulator of inflammation. However, its effect in the endometrial microenvironment is poorly explained. This study aimed to evaluate the role of endogenous AnxA1 in an endometritis mouse model induced by lipopolysaccharide (LPS). Female C57BL/6 wild-type (WT) and AnxA1-/- mice were divided into two groups: SHAM and LPS. To induce endometritis, mice received a vaginal infusion of 50 μL of LPS (1 mg/mL) dissolved in phosphate-buffered saline. After 24 h, the mice were euthanized, and blood and uteri samples were collected. The endometrium inflammatory scores were significantly increased in the LPS-treated group. AnxA1-/- mice from the LPS group demonstrated a significant increase in the number of degranulated mast cell levels compared to AnxA1-/- SHAM mice. The Western blotting analysis revealed that a lack of AnxA1 promoted the upregulation of NLRP3 and pro-IL-1β in the acute endometritis animal model compared to WT LPS animals. LPS-induced endometritis increased the number of blood peripheral leukocytes in both WT and AnxA1-/- mice compared with SHAM group mice (p < 0.001). AnxA1-/- mice also showed increased plasma levels of IL-1β (p < 0.01), IL-6, IL-10, IL-17, and TNF-α (p < 0.05) following LPS-induced endometritis. In conclusion, a lack of endogenous AnxA1 exacerbated the inflammatory response in an endometritis model via NLRP3 dysregulation, increased uterine mast cell activation, and plasma pro-inflammatory cytokine release.

Clinical Characteristics of Cryopyrin-Associated Periodic Syndrome and Long-Term Real-World Efficacy and Tolerability of Canakinumab in Japan: Results of a Nationwide Survey

OBJECTIVE

We assess the clinical characteristics of patients with cryopyrin-associated periodic syndrome (CAPS) in Japan and evaluate the real-world efficacy and safety of interleukin-1 (IL-1) inhibitors, primarily canakinumab.

METHODS

Clinical information was collected retrospectively, and serum concentrations of canakinumab and cytokines were analyzed.

RESULTS

A total of 101 patients were included, with 86 and 15 carrying heterozygous germline and somatic mosaic mutations, respectively. We identified 39 mutation types, and the common CAPS-associated symptoms corresponded with those in previous reports. Six patients (5.9% of all patients) died, with four of the deaths caused by CAPS-associated symptoms. Notably, 73.7% of patients (100%, 79.6%, and 44.4% of familial cold autoinflammatory syndrome, Muckle-Wells syndrome, and chronic infantile neurological cutaneous articular syndrome/neonatal onset multisystem inflammatory disease, respectively) achieved complete remission with canakinumab, and early therapeutic intervention was associated with better auditory outcomes. In some patients, canakinumab treatment stabilized the progression of epiphysial overgrowth and improved height gain, visual acuity, and renal function. However, 23.7% of patients did not achieve inflammatory remission with crucial deterioration of organ damage, with two dying while receiving high-dose canakinumab treatment. Serological analysis of canakinumab and cytokine concentrations revealed that the poor response was not related to canakinumab shortage. Four inflammatory nonremitters developed inflammatory bowel disease (IBD)-unclassified during canakinumab treatment. Dual biologic therapy with canakinumab and anti-tumor necrosis factor-α agents was effective for IBD- and CAPS-associated symptoms not resolved by canakinumab monotherapy.

CONCLUSION

This study provides one of the largest epidemiologic data sets for CAPS. Although early initiation of anti-IL-1 treatment with canakinumab is beneficial for improving disease prognosis, some patients do not achieve remission despite a high serum concentration of canakinumab. Moreover, IBD may develop in CAPS after canakinumab treatment.

Intestinal microbiota via NLRP3 inflammasome dependent neuronal pyroptosis mediates anxiety-like behaviour in mice exposed to 3.5 GHz radiofrequency radiation

The rapid development of 5G communication technology has increased public concern about the potential adverse effects on human health. Till now, the impacts of radiofrequency radiation (RFR) from 5G communication on the central nervous system and gut-brain axis are still unclear. Therefore, we investigated the effects of 3.5 GHz (a frequency commonly used in 5G communication) RFR on neurobehavior, gut microbiota, and gut-brain axis metabolites in mice. The results showed that exposure to 3.5 GHz RFR at 50 W/m2 for 1 h over 35 d induced anxiety-like behaviour in mice, accompanied by NLRP3-dependent neuronal pyroptosis in CA3 region of the dorsal hippocampus. In addition, the microbial composition was widely divergent between the sham and RFR groups. 3.5 GHz RFR also caused changes in metabolites of feces, serum, and brain. The differential metabolites were mainly enriched in glycerophospholipid metabolism, tryptophan metabolism, and arginine biosynthesis. Further correlation analysis showed that gut microbiota dysbiosis was associated with differential metabolites. Based on the above results, we speculate that dysfunctional intestinal flora and metabolites may be involved in RFR-induced anxiety-like behaviour in mice through neuronal pyroptosis in the brain. The findings provide novel insights into the mechanism of 5G RFR-induced neurotoxicity.

hP-MSCs attenuate severe acute pancreatitis in mice via inhibiting NLRP3 inflammasome-mediated acinar cell pyroptosis

BACKGROUND

Severe acute pancreatitis (SAP) is a serious gastrointestinal disease that is facilitated by pancreatic acinar cell death. The protective role of human placental mesenchymal stem cells (hP-MSCs) in SAP has been demonstrated in our previous studies. However, the underlying mechanisms of this therapy remain unclear. Herein, we investigated the regularity of acinar cell pyroptosis during SAP and investigated whether the protective effect of hP-MSCs was associated with the inhibition of acinar cell pyroptosis.

METHODS

A mouse model of SAP was established by the retrograde injection of sodium taurocholate (NaTC) solution in the pancreatic duct. For the hP-MSCs group, hP-MSCs were injected via the tail vein and were monitored in vivo. Transmission electron microscopy (TEM) was used to observe the pyroptosis-associated ultramorphology of acinar cells. Immunofluorescence and Western blotting were subsequently used to assess the localization and expression of pyroptosis-associated proteins in acinar cells. Systemic inflammation and local injury-associated parameters were evaluated.

RESULTS

Acinar cell pyroptosis was observed during SAP, and the expression of pyroptosis-associated proteins initially increased, peaked at 24 h, and subsequently showed a decreasing trend. hP-MSCs effectively attenuated systemic inflammation and local injury in the SAP model mice. Importantly, hP-MSCs decreased the expression of pyroptosis-associated proteins and the activity of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in acinar cells.

CONCLUSIONS

Our study demonstrates the regularity and important role of acinar cell pyroptosis during SAP. hP-MSCs attenuate inflammation and inhibit acinar cell pyroptosis via suppressing NLRP3 inflammasome activation, thereby exerting a protective effect against SAP.

Cellular Alterations in Immune Checkpoint Inhibitor Therapy-Related Cardiac Dysfunction

PURPOSE OF REVIEW

Immune checkpoint inhibitor (ICI) therapy has emerged as a pivotal advancement in cancer treatment, but the widespread adoption has given rise to a growing number of reports detailing significant cardiovascular toxicity. This review concentrates on elucidating the mechanisms behind ICI-related cardiovascular complications, emphasizing preclinical and mechanistic data.

RECENT FINDINGS

Accumulating evidence indicates a more significant role of immune checkpoints in maintaining cardiac integrity than previously understood, and new key scientific data are available to improve our understanding of ICI-related cardiovascular toxicity, including hidden cardiotoxicity. New avenues for innovative concepts are hypothesized, and opportunities to leverage the knowledge from ICI-therapy for pioneering approaches in related scientific domains can be derived from the latest scientific projects. Cardiotoxicity from ICI therapy is a paramount challenge for cardio-oncology. Understanding the underlying effects builds the foundation for tailored cardioprotective approaches in the growing collective at risk for severe cardiovascular complications.

Pyroptosis in sepsis induced organ dysfunction

As an uncontrolled inflammatory response to infection, sepsis and sepsis induced organ dysfunction are great threats to the lives of septic patients. Unfortunately, the pathogenesis of sepsis is complex and multifactorial, which still needs to be elucidated. Pyroptosis is a newly discovered atypical form of inflammatory programmed cell death, which depends on the Caspase-1 dependent classical pathway or the non-classical Caspase-11 (mouse) or Caspase-4/5 (human) dependent pathway. Many studies have shown that pyroptosis is related to sepsis. The Gasdermin proteins are the key molecules in the membrane pores formation in pyroptosis. After cut by inflammatory caspase, the Gasdermin N-terminal fragments with perforation activity are released to cause pyroptosis. Pyroptosis is closely related to the occurrence and development of sepsis induced organ dysfunction. In this review, we summarized the molecular mechanism of pyroptosis, the key role of pyroptosis in sepsis and sepsis induced organ dysfunction, with the aim to bring new diagnostic biomarkers and potential therapeutic targets to improve sepsis clinical treatments.