CARD8 polymorphisms among bacterial meningitis patients in North-West Ethiopia.

BACKGROUND: The severity of infectious disease outcomes is dependent on the virulence factors of the pathogen and the host immune response. CARD8 is a major regulator of the innate immune proinflammatory response and has been suggested to modulate the host response to common inflammatory diseases. In the present study, the C10X genetic polymorphism in the CARD8 gene was investigated in relation to bacterial meningitis. METHODS: A total of 400 clinically suspected meningitis patients hospitalized at the University of Gondar Hospital were enrolled in the study. Cerebrospinal fluid (CSF) and blood samples were collected for laboratory investigations. The collected CSF was cultured, and all the results obtained from the culture were confirmed using direct RT‒PCR. Genotyping of whole-blood samples was performed using a TaqMan assay. The results were compared with apparently healthy controls and with PCR-negative meningitis suspected patients. RESULTS: Of the included patients, 57% were men and the most common clinical signs and symptoms were fever (81%), headache (80%), neck stiffness (76%), nausea (68%), and vomiting (67%). Microbiology culture identified 7 patients with bacterial meningitis caused by Neisseria meningitidis (n = 4) and Streptococcus pneumoniae (n = 3). The RT-PCR revealed 39 positive samples for N. meningitidis (n = 10) and S. pneumoniae (n = 29). A total of 332 whole-blood samples were genotyped with the following results: 151 (45.5%) C10X heterozygotes, 59 (17.7%) C10X homozygotes and 122 (36.7%) wild genotypes. The polymorphic gene carriers among laboratory confirmed, clinically diagnosed meningitis and healthy controls were 23(46%), 246(40%), and 1526(39%), respectively with OR = 1.27 (0.7-2.3) and OR = 1.34 (0.76-2.4). The presence of the C10X polymorphism in the CARD8 gene was more prevalent in suspected meningitis patients than in healthy controls (OR 1.2; 1.00-1.5). Homozygote C10X polymorphic gene carriers were more susceptible to infectious disease. The presence of viable or active bacterial infection was found to be associated with the presence of heterozygous C10X carriers. CONCLUSIONS: A greater proportion of C10X in the CARD8 gene in confirmed bacterial meningitis patients and clinically diagnosed meningitis patients than in healthy controls. Homozygote C10X polymorphic gene carriers were more susceptible to infectious disease than heterozygote gene carriers and healthy controls.

Heterogeneity of Salmonella enterica lipopolysaccharide counteracts macrophage and antimicrobial peptide defenses.

Salmonella enterica is comprised of over 2,500 serovars, in which non-typhoidal serovars (NTS), Enteritidis (SE), and Typhimurium (STM) are the most clinically associated with human infections. Although NTS have similar genetic elements to cause disease, phenotypic variation including differences in lipopolysaccharide (LPS) composition may control immune evasion. Here, we demonstrate that macrophage host defenses and LL-37 antimicrobial efficacy against SE and STM are substantially altered by LPS heterogeneity. We found that SE evades macrophage killing by inhibiting phagocytosis while STM survives better intracellularly post-phagocytosis. SE-infected macrophages failed to activate the inflammasomes and subsequently produced less interleukin-1ß (IL-1ß), IL-18, and interferon λ. Inactivation of LPS biosynthesis genes altered LPS composition, and the SE LPS-altered mutants could no longer inhibit phagocytosis, inflammasome activation, and type II interferon signaling. In addition, SE and STM showed differential susceptibility to the antimicrobials LL-37 and colistin, and alteration of LPS structure substantially increased susceptibility to these molecules. Collectively, our findings highlight that modification of LPS composition by Salmonella increases resistance to host defenses and antibiotics.

S-acylation of NLRP3 provides a nigericin sensitive gating mechanism that controls access to the Golgi.

NLRP3 is an inflammasome seeding pattern recognition receptor activated in response to multiple danger signals which perturb intracellular homeostasis. Electrostatic interactions between the NLRP3 polybasic (PB) region and negatively charged lipids on the trans-Golgi network (TGN) have been proposed to recruit NLRP3 to the TGN. In this study, we demonstrate that membrane association of NLRP3 is critically dependant on S-acylation of a highly conserved cysteine residue (Cys-130), which traps NLRP3 in a dynamic S-acylation cycle at the Golgi, and a series of hydrophobic residues preceding Cys-130 which act in conjunction with the PB region to facilitate Cys-130 dependent Golgi enrichment. Due to segregation from Golgi localised thioesterase enzymes caused by a nigericin induced breakdown in Golgi organisation and function, NLRP3 becomes immobilised on the Golgi through reduced de-acylation of its Cys-130 lipid anchor, suggesting that disruptions in Golgi homeostasis are conveyed to NLRP3 through its acylation state. Thus, our work defines a nigericin sensitive S-acylation cycle that gates access of NLRP3 to the Golgi.

From fat to fire: The lipid-inflammasome connection.

Inflammasomes are multiprotein complexes that play a crucial role in regulating immune responses by governing the activation of Caspase-1, the secretion of pro-inflammatory cytokines, and the induction of inflammatory cell death, pyroptosis. The inflammasomes are pivotal in effective host defense against a range of pathogens. Yet, overt activation of inflammasome signaling can be detrimental. The most well-studied NLRP3 inflammasome has the ability to detect a variety of stimuli including pathogen-associated molecular patterns, environmental irritants, and endogenous stimuli released from dying cells. Additionally, NLRP3 acts as a key sensor of cellular homeostasis and can be activated by disturbances in diverse metabolic pathways. Consequently, NLRP3 is considered a key player linking metabolic dysregulation to numerous inflammatory disorders such as gout, diabetes, and atherosclerosis. Recently, compelling studies have highlighted a connection between lipids and the regulation of NLRP3 inflammasome. Lipids are integral to cellular processes that serve not only in maintaining the structural integrity and subcellular compartmentalization, but also in contributing to physiological equilibrium. Certain lipid species are known to define NLRP3 subcellular localization, therefore directly influencing the site of inflammasome assembly and activation. For instance, phosphatidylinositol 4-phosphate plays a crucial role in NLRP3 localization to the trans Golgi network. Moreover, new evidence has demonstrated the roles of lipid biosynthesis and trafficking in activation of the NLRP3 inflammasome. This review summarizes and discusses these emerging and varied roles of lipid metabolism in inflammasome activation. A deeper understanding of lipid-inflammasome interactions may open new avenues for therapeutic interventions to prevent or treat chronic inflammatory and autoimmune conditions.

Role of caspase-11 non-canonical inflammasomes in retinal ischemia/reperfusion injury.

BACKGROUND: Retinal ischemia/reperfusion (IR) injury is a common pathological process in many ophthalmic diseases. Interleukin-1ß (IL-1ß) is an important inflammatory factor involved in the pathology of retinal IR injury, but the mechanism by which IL-1ß is regulated in such injury remains unclear. Caspase-11 non-canonical inflammasomes can regulate the synthesis and secretion of IL-1ß, but its role in retinal IR injury has not been elucidated. This study aimed to evaluate the role of caspase-11 non-canonical inflammasomes in retinal IR injury. METHODS: Retinal IR injury was induced in C57BL/6J mice by increasing the intraocular pressure to 110 mmHg for 60 min. The post-injury changes in retinal morphology and function and in IL-1ß expression were compared between caspase-11 gene knockout (caspase-11-/-) mice and wild-type (WT) mice. Morphological and functional changes were evaluated using hematoxylin-eosin staining and retinal whole mount staining and using electroretinography (ERG), respectively. IL-1ß expression in the retina was measured using enzyme-linked immunosorbent assay (ELISA). The levels of caspase-11-related protein were measured using western blot analysis. The location of caspase-11 in the retina was determined via immunofluorescence staining. Mouse type I astrocytes C8-D1A cells were used to validate the effects of caspase-11 simulation via hypoxia in vitro. Small-interfering RNA targeting caspase-11 was constructed. Cell viability was evaluated using the MTT assay. IL-1ß expression in supernatant and cell lysate was measured using ELISA. The levels of caspase-11-related protein were measured using western blot analysis. RESULTS: Retinal ganglion cell death and retinal edema were more ameliorated, and the ERG b-wave amplitude was better after retinal IR injury in caspase-11-/- mice than in WT mice. Further, caspase-11-/- mice showed lower protein expressions of IL-1ß, cleaved caspase-1, and gasdermin D (GSDMD) in the retina after retinal IR injury. Caspase-11 protein was expressed in retinal glial cells, and caspase-11 knockdown played a protective role against hypoxia in C8-D1A cells. The expression levels of IL-1ß, cleaved caspase-1, and GSDMD were inhibited after hypoxia in the si-caspase-11 constructed cells. CONCLUSIONS: Retinal IR injury activates caspase-11 non-canonical inflammasomes in glial cells of the retina. This results in increased protein levels of GSDMD and IL-1ß and leads to damage in the inner layer of the retina.

NLRP3 inflammasome activation contributes to the development of the pro-fibrotic phenotype of lung fibroblasts.

Idiopathic pulmonary fibrosis (IPF) is an irreversible progressive interstitial lung disease of unknown cause. The poorly understood pathophysiology of IPF poses substantial challenges to the development of effective anti-lung fibrotic drugs. The NLRP3 inflammasome, a key component of the innate immune system, has recently been linked to the pathogenesis of lung fibrosis. However, the specific contributions of NLRP3 inflammasomes to determination of the pro-fibrotic phenotype of lung fibroblasts, which play a central role in the production of extracellular matrix protein, remain to be investigated. Therefore, the present study was performed to elucidate the involvement of NLRP3 inflammasome signalling pathways in modulation of lung fibroblast proliferation and differentiation. We found that activation of NLRP3 inflammasomes increased in lung fibroblasts derived from individuals with pulmonary fibrosis and in normal lung fibroblasts stimulated with transforming growth factor ß and platelet-derived growth factor. Importantly, blockage of NLRP3 inflammasome signalling, either by gene silencing of NLRP3 or using pharmacological inhibitors of NLRP3, caspase-1, or IL-1 receptor, inhibited the proliferation, differentiation, and extracellular matrix protein synthesis of activated lung fibroblasts. Moreover, induction of the reactive oxygen species/thioredoxin-interacting protein axis, an upstream signalling pathway of NLRP3 inflammasomes, was essential for maintenance of the pro-fibrotic phenotype of lung fibroblasts. Interestingly, treatments with pharmacological inhibitors of NLRP3 inflammasomes prevented the progression of bleomycin-induced pulmonary fibrosis in mice. Collectively, these findings suggest that aberrant activation of NLRP3 inflammasomes is a critical event in the pathogenesis of IPF and that targeting NLRP3 inflammasomes may serve as a therapeutic strategy for IPF.

Can We Exploit Inflammasomes for Host-Directed Therapy in the Fight against Mycobacterium tuberculosis Infection?

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tb), is a major global health issue, with around 10 million new cases annually. Advances in TB immunology have improved our understanding of host signaling pathways, leading to innovative therapeutic strategies. Inflammasomes, protein complexes organized by cytosolic pattern recognition receptors (PRRs), play a crucial role in the immune response to M. tb by activating caspase 1, which matures proinflammatory cytokines IL1ß and IL18. While inflammation is necessary to fight infection, excessive or dysregulated inflammation can cause tissue damage, highlighting the need for precise inflammasome regulation. Drug-resistant TB strains have spurred research into adjunctive host-directed therapies (HDTs) that target inflammasome pathways to control inflammation. Canonical and non-canonical inflammasome pathways can trigger excessive inflammation, leading to immune system exhaustion and M. tb spread. Novel HDT interventions can leverage precision medicine by tailoring treatments to individual inflammasome responses. Studies show that medicinal plant derivatives like silybin, andrographolide, and micheliolide and small molecules such as OLT1177, INF39, CY-09, JJ002, Ac-YVAD-cmk, TAK-242, and MCC950 can modulate inflammasome activation. Molecular tools like gene silencing and knockouts may also be used for severe TB cases. This review explores these strategies as potential adjunctive HDTs in fighting TB.

FDA-approved cannabidiol [Epidiolex®] alleviates Gulf War Illness-linked cognitive and mood dysfunction, hyperalgesia, neuroinflammatory signaling, and declined neurogenesis.

BACKGROUND: Chronic Gulf War Illness (GWI) is characterized by cognitive and mood impairments, as well as persistent neuroinflammation and oxidative stress. This study aimed to investigate the efficacy of Epidiolex®, a Food and Drug Administration (FDA)-approved cannabidiol (CBD), in improving brain function in a rat model of chronic GWI. METHODS: Six months after exposure to low doses of GWI-related chemicals [pyridostigmine bromide, N,N-diethyl-meta-toluamide (DEET), and permethrin (PER)] along with moderate stress, rats with chronic GWI were administered either vehicle (VEH) or CBD (20 mg/kg, oral) for 16 weeks. Neurobehavioral tests were conducted on 11 weeks after treatment initiation to evaluate the performance of rats in tasks related to associative recognition memory, object location memory, pattern separation, and sucrose preference. The effect of CBD on hyperalgesia was also examined. The brain tissues were processed for immunohistochemical and molecular studies following behavioral tests. RESULTS: GWI rats treated with VEH exhibited impairments in all cognitive tasks and anhedonia, whereas CBD-treated GWI rats showed improvements in all cognitive tasks and no anhedonia. Additionally, CBD treatment alleviated hyperalgesia in GWI rats. Analysis of hippocampal tissues from VEH-treated rats revealed astrocyte hypertrophy and increased percentages of activated microglia presenting NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) complexes as well as elevated levels of proteins involved in NLRP3 inflammasome activation and Janus kinase/signal transducers and activators of the transcription (JAK/STAT) signaling. Furthermore, there were increased concentrations of proinflammatory and oxidative stress markers along with decreased neurogenesis. In contrast, the hippocampus from CBD-treated GWI rats displayed reduced levels of proteins mediating the activation of NLRP3 inflammasomes and JAK/STAT signaling, normalized concentrations of proinflammatory cytokines and oxidative stress markers, and improved neurogenesis. Notably, CBD treatment did not alter the concentration of endogenous cannabinoid anandamide in the hippocampus. CONCLUSIONS: The use of an FDA-approved CBD (Epidiolex®) has been shown to effectively alleviate cognitive and mood impairments as well as hyperalgesia associated with chronic GWI. Importantly, the improvements observed in rats with chronic GWI in this study were attributed to the ability of CBD to significantly suppress signaling pathways that perpetuate chronic neuroinflammation.

Amplifying protection against acute lung injury: Targeting both inflammasome and cGAS-STING pathway by Lonicerae Japonicae Flos-Forsythiae Fructus drug pair.

Objective: Acute lung injury (ALI) is characterized by inflammation and currently lacks an efficacious pharmacological intervention. The medicine combination of Lonicerae Japonicae Flos (LJF) and Forsythiae Fructus (FF) demonstrates combined properties in its anti-infective, anti-inflammatory, and therapeutic effects, particularly in alleviating respiratory symptoms. In previous studies, Chinese medicine has shown promising efficacy in lipopolysaccharides (LPS)-induced ALI. However, there have been no reports of LJF and FF pairing for lung injury. The aim of this study is to compare the efficacy of herb pair Lonicerae Japonicae Flos-Forsythiae Fructus (LF) with LJF or FF alone in the treatment of ALI, and to explore whether LJF and FF have a combined effect in the treatment of lung injury, along with the underlying mechanism involved. Methods: A total of 36 mice were divided into six groups (control, model, LJF, FF, LF, dexamethasone) based on the treatments they received after undergoing sham-operation/LPS tracheal instillation. H&E staining and pulmonary edema indexes were used to evaluate lung injury severity. Alveolar exudate cells (AECs) were counted based on cell count in bronchoalveolar lavage fluid (BALF), and neutrophil percentage in BALF was measured using flow cytometry. Myeloperoxidase (MPO) activity in BALF was measured using enzyme-linked immunosorbent assay (ELISA), while the production of IL-1ß, TNF-α, and IL-6 in the lung and secretion level of them in BALF were detected by quantitative polymerase chain reaction (qPCR) and ELISA. The effect of LJF, FF, and LF on the expression of Caspase-1 and IL-1ß proteins in bone marrow derived macrophages (BMDMs) supernatant was assessed using Western blot method under various inflammasome activation conditions. In addition, the concentration of IL-1ß and changes in lactatedehydrogenase (LDH) release levels in BMDMs supernatant after LJF, FF, and LF administration, respectively, were measured using ELISA. Furthermore, the effects of LJF, FF and LF on STING and IRF3 phosphorylation in BMDMs were detected by Western blot, and the mRNA changes of IFN-ß, TNF-α, IL-6 and CXCL10 in BMDMs were detected by qPCR. Results: LF significantly attenuated the damage to alveolar structures, pulmonary hemorrhage, and infiltration of inflammatory cells induced by LPS. This was evidenced by a decrease in lung index score and wet/dry weight ratio. Treatment with LF significantly reduced the total number of neutrophil infiltration by 75% as well as MPO activity by 88%. The efficacy of LF in reducing inflammatory factors IL-1ß, TNF-α, and IL-6 in the lungs surpasses that of LJF or FF, approaching the effectiveness of dexamethasone. In BMDMs, the co-administration of 0.2 mg/mL of LJF and FF demonstrated superior inhibitory effects on the expression of nigericin-stimulated Caspase-1 and IL-1ß, as well as the release levels of LDH, compared to individual treatments. Similarly, the combination of 0.5 mg/mL LJF and FF could better inhibit the phosphorylation levels of STING and IRF3 and the production of IFN-ß, TNF-α, IL-6, and CXCL10 in response to ISD stimulation. Conclusion: The combination of LJF and FF increases the therapeutic effect on LPS-induced ALI, which may be mechanistically related to the combined effect inhibition of cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) and NOD-like receptor family protein 3 (NLRP3) inflammasomes pathways by LJF and FF. Our study provides new medicine candidates for the clinical treatment of ALI.

EZH2-H3K27me3-Mediated Epigenetic Silencing of DKK1 Induces Nucleus Pulposus Cell Pyroptosis in Intervertebral Disc Degeneration by Activating NLRP3 and NAIP/NLRC4.

Nucleus pulposus (NP) cell pyroptosis is crucial for intervertebral disc degeneration (IDD). However, the precise mechanisms underlying pyroptosis in IDD remain elusive. Therefore, this study aimed to investigate how dickkopf-1 (DKK1) influences NP cell pyroptosis and delineate the regulatory mechanisms of IDD. Behavioral tests and histological examinations were conducted in rat IDD models to assess the effect of DKK1 on the structure and function of intervertebral discs. Detected pyroptosis levels using Hoechst 33,342/propidium iodide (PI) double staining, and determined pyroptosis-related protein expression via western blotting. The cellular mechanisms of DKK1 in pyroptosis were explored in interleukin (IL)-1ß-induced NP cells transfected with or without DKK1 overexpression plasmids (oe-DKK1). In addition, IL-1ß-treated NP cells transfected with sh-EZH2 and/or sh-DKK1 were utilized to clarify the interplay between the enhancer of zeste homologue 2 (EZH2) and DKK1 in pyroptosis. Additionally, the epigenetic regulation of DKK1 by EZH2 was explored in NP cells treated with the EZH2 inhibitors GSK126/DZNep. DKK1 expression decreased in IDD rats. Transfection with oe-DKK1 reduced pro-inflammatory factors and extracellular matrix markers in IDD rats. In IL-1ß-induced NP cells, DKK1 overexpression suppressed pyroptosis and inhibited the NLRP3 and NAIP/NLRC4 inflammasome activation. EZH2 knockdown increased DKK1 expression and reduced pyroptosis-related proteins. Conversely, DKK1 downregulation reversed the inhibitory effects of EZH2 knockdown on pyroptosis. Furthermore, EZH2 suppressed DKK1 expression via H3K27 methylation at the DKK1 promoter. EZH2 negatively regulates DKK1 expression via H3K27me3 methylation, promoting NP cell pyroptosis in IDD patients. This regulatory effect involves the activation of NLRP3 and NAIP/NLRC4 inflammasomes.

Deciphering the intricate dynamics of inflammasome regulation in visceral and post-kala-azar dermal leishmaniasis: A meta-analysis of consistencies.

Post Kala-azar dermal leishmaniasis (PKDL) arises as a significant dermal sequel following Visceral leishmaniasis (VL) caused by protozoan parasite Leishmania donovani (LD). PKDL acts as a significant constrain for VL elimination serving as a crucial reservoir for LD. PKDL patients exhibit depigmented macular and papular lesions on their skin, which results in social discrimination due to loss of natural skin color. Inflammatory reactions, prevalent in both VL and PKDL, potentially lead to tissue damage in areas harboring the parasite. Disruption of the immune-inflammasomal network not only facilitates LD persistence but also leads to the skin hypopigmentation seen in PKDL, impacting social well-being. Activation of inflammasomal markers like STAT1, NLRP1, NLRP3, AIM2, CASP11, and NLRP12 have been identified as a common host-defense mechanism across various Leishmania infections. Conversely, Leishmania modulates inflammasome activation to sustain its presence within the host. Nevertheless, in specific instances of Leishmania infection, inflammasome activation can worsen disease pathology by promoting parasite proliferation and persistence. This study encompasses recent transcriptomic analyses conducted between 2016 and 2023 on human and murine subjects afflicted with VL/PKDL, elucidating significant alterations in inflammasomal markers in both conditions. It offers a comprehensive understanding how these markers contribute in disease progression, drawing upon available literature for logical analysis. Furthermore, our analysis identifies validated miRNA network that could potentially disrupt this crucial immune-inflammasomal network, thereby offering a plausible explanation on how secreted LD-factors could enable membrane-bound LD, isolated from the host cytoplasm, to modulate cytoplasmic inflammasomal markers. Insights from this study could guide the development of host-directed therapeutics to impede transmission and address hypopigmentation, thereby mitigating the social stigma associated with PKDL.

DAMP-ing IBD: Extinguish the Fire and Prevent Smoldering.

In inflammatory bowel diseases (IBD), the most promising therapies targeting cytokines or immune cell trafficking demonstrate around 40% efficacy. As IBD is a multifactorial inflammation of the intestinal tract, a single-target approach is unlikely to solve this problem, necessitating an alternative strategy that addresses its variability. One approach often overlooked by the pharmaceutically driven therapeutic options is to address the impact of environmental factors. This is somewhat surprising considering that IBD is increasingly viewed as a condition heavily influenced by such factors, including diet, stress, and environmental pollution-often referred to as the "Western lifestyle". In IBD, intestinal responses result from a complex interplay among the genetic background of the patient, molecules, cells, and the local inflammatory microenvironment where danger- and microbe-associated molecular patterns (D/MAMPs) provide an adjuvant-rich environment. Through activating DAMP receptors, this array of pro-inflammatory factors can stimulate, for example, the NLRP3 inflammasome-a major amplifier of the inflammatory response in IBD, and various immune cells via non-specific bystander activation of myeloid cells (e.g., macrophages) and lymphocytes (e.g., tissue-resident memory T cells). Current single-target biological treatment approaches can dampen the immune response, but without reducing exposure to environmental factors of IBD, e.g., by changing diet (reducing ultra-processed foods), the adjuvant-rich landscape is never resolved and continues to drive intestinal mucosal dysregulation. Thus, such treatment approaches are not enough to put out the inflammatory fire. The resultant smoldering, low-grade inflammation diminishes physiological resilience of the intestinal (micro)environment, perpetuating the state of chronic disease. Therefore, our hypothesis posits that successful interventions for IBD must address the complexity of the disease by simultaneously targeting all modifiable aspects: innate immunity cytokines and microbiota, adaptive immunity cells and cytokines, and factors that relate to the (micro)environment. Thus the disease can be comprehensively treated across the nano-, meso-, and microscales, rather than with a focus on single targets. A broader perspective on IBD treatment that also includes options to adapt the DAMPing (micro)environment is warranted.

Anoectochilus roxburghii polysaccharide reduces D-GalN/LPS-induced acute liver injury by regulating the activation of multiple inflammasomes.

BACKGROUND: Acute liver injury (ALI) is a serious syndrome with a high mortality rate due to viral infection, toxic exposure, and autoimmunity, and its severity can range from mildly elevated liver enzymes to severe liver failure. Activation of the nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome is closely associated with the development of ALI, and the search for an inhibitor targeting this pathway may be a novel therapeutic option. Anoectochilus roxburghii polysaccharide (ARP) is a biologically active ingredient extracted from Anoectochilus roxburghii with immunomodulatory, antioxidant, and anti-inflammatory bioactivities and pharmacological effects. In this study, we focused on D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced acute liver injury by ARP through inhibition of NLRP3 inflammasome. METHODS: An inflammasome activation model was established in bone marrow-derived macrophages (BMDMs) to investigate the effects of ARP on caspase-1 cleavage, IL-1ß secretion, and ASC oligomerization in inflammasomes under different agonists. We used the D-GalN/LPS-induced acute liver injury model in mice, intraperitoneally injected ARP or MCC950, and collected liver tissues, serum, and intraperitoneal lavage fluid for pathological and biochemical indexes. RESULTS: ARP effectively inhibited the activation of the NLRP3 inflammasome and had an inhibitory effect on non-classical NLRP3, AIM2, and NLRC4 inflammasomes. It also effectively inhibited the oligomerization of apoptosis-associated speck-like protein (ASC) from a variety of inflammatory vesicles. Meanwhile, ARP has good therapeutic effects on acute liver injury induced by D-GaIN/LPS. CONCLUSION: The inhibitory effect of ARP on a wide range of inflammasomes, as well as its excellent protection against acute liver injury, suggests that ARP may be a candidate for acute liver injury.

Unanticipated Loss of Inflammasomes in Birds.

Inflammasomes are multiprotein complexes that form in response to ligands originating from pathogens as well as alterations of normal cell physiology caused by infection or tissue damage. These structures engage a robust inflammatory immune response that eradicates environmental microbes before they cause disease, and slow the growth of bona fide pathogens. Despite their undeniable utility in immunity, inflammasomes are radically reduced in birds. Perhaps most surprising is that, within all birds, NLRP3 is retained, while its signaling adapter ASC is lost, suggesting that NLRP3 signals via a novel unknown adapter. Crocodilian reptiles and turtles, which share a more recent common ancestor with birds, retain many of the lost inflammasome components, indicating that the deletion of inflammasomes occurred after birds diverged from crocodiles. Some bird lineages have even more extensive inflammasome loss, with songbirds continuing to pare down their inflammasomes until only NLRP3 and CARD8 remain. Remarkably, songbirds have lost caspase-1 but retain the downstream targets of caspase-1: IL-1ß, IL-18, and the YVAD-linker encoding gasdermin A. This suggests that inflammasomes can signal through alternative proteases to activate cytokine maturation and pyroptosis in songbirds. These observations may reveal new contexts of activation that may be relevant to mammalian inflammasomes and may suggest new avenues of research to uncover the enigmatic nature of the poorly understood NLRP3 inflammasome.

From inflammatory signaling to neuronal damage: Exploring NLR inflammasomes in ageing neurological disorders.

The persistence of neuronal degeneration and damage is a major obstacle in ageing medicine. Nucleotide-binding oligomerization domain (NOD)-like receptors detect environmental stressors and trigger the maturation and secretion of pro-inflammatory cytokines that can cause neuronal damage and accelerate cell death. NLR (NOD-like receptors) inflammasomes are protein complexes that contain NOD-like receptors. Studying the role of NLR inflammasomes in ageing-related neurological disorders can provide valuable insights into the mechanisms of neurodegeneration. This includes investigating their activation of inflammasomes, transcription, and capacity to promote or inhibit inflammatory signaling, as well as exploring strategies to regulate NLR inflammasomes levels. This review summarizes the use of NLR inflammasomes in guiding neuronal degeneration and injury during the ageing process, covering several neurological disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, stroke, and peripheral neuropathies. To improve the quality of life and slow the progression of neurological damage, NLR-based treatment strategies, including inhibitor-related therapies and physical therapy, are presented. Additionally, important connections between age-related neurological disorders and NLR inflammasomes are highlighted to guide future research and facilitate the development of new treatment options.

A novel role of AIM2 inflammasome-mediated pyroptosis in radiofrequency ablation of hepatocellular carcinoma.

INTRODUCTION AND OBJECTIVES: The absence of melanoma 2 (AIM2) protein triggers the activation of the inflammasome cascade. It is unclear whether AIM2 plays a role in hepatocellular carcinoma (HCC) and radiofrequency ablation (RFA), which uses radiofrequency waves to treat tumors. In this study, we investigated if RFA could induce pyroptosis, also called cell inflammatory necrosis, in HCC through AIM2-inflammasome signaling in vivo and in vitro. MATERIALS AND METHODS: BALB/c nude mice were used to generate HepG2 or SMMC-7721 cell-derived tumor xenografts. HCC cells with knockdown or overexpression of AIM2 were created using short hairpin RNA (shRNA) and expression vector transfection, respectively, for functional and mechanistic studies. Downstream effects were examined using flow cytometry, qRT-PCR, ELISAs, and other molecular assays. RESULTS: RFA significantly suppressed tumor growth in HCC cell xenografts. Flow cytometry analysis revealed that RFA could induce pyroptosis. Furthermore, AIM2, NLRP3, caspase-1, γ-H2AX, and DNA-PKc had significantly greater expression levels in liver tissues from mice treated with RFA compared with those of the controls. Additionally, interleukin (IL)-1ß and IL-18 expression levels were significantly higher in the HCC cell-derived xenograft mice treated with RFA compared with those without RFA. Notably, a significantly greater effect was achieved in the RFA complete ablation group versus the partial ablation group. Knockdown or overexpression of AIM2 in HCC cells demonstrated that AIM2 exerted a role in RFA-induced pyroptosis. CONCLUSIONS: RFA can suppress HCC tumor growth by inducing pyroptosis via AIM2. Therefore, therapeutically intervening with AIM2-mediated inflammasome signaling may help improve RFA treatment outcomes for HCC patients.

Platelet transcription factors license the pro-inflammatory cytokine response of human monocytes.

In humans, blood Classical CD14+ monocytes contribute to host defense by secreting large amounts of pro-inflammatory cytokines. Their aberrant activity causes hyper-inflammation and life-threatening cytokine storms, while dysfunctional monocytes are associated with 'immunoparalysis', a state of immune hypo responsiveness and reduced pro-inflammatory gene expression, predisposing individuals to opportunistic infections. Understanding how monocyte functions are regulated is critical to prevent these harmful outcomes. We reveal platelets' vital role in the pro-inflammatory cytokine responses of human monocytes. Naturally low platelet counts in patients with immune thrombocytopenia or removal of platelets from healthy monocytes result in monocyte immunoparalysis, marked by impaired cytokine response to immune challenge and weakened host defense transcriptional programs. Remarkably, supplementing monocytes with fresh platelets reverses these conditions. We discovered that platelets serve as reservoirs of key cytokine transcription regulators, such as NF-κB and MAPK p38, and pinpointed the enrichment of platelet NF-κB2 in human monocytes by proteomics. Platelets proportionally restore impaired cytokine production in human monocytes lacking MAPK p38α, NF-κB p65, and NF-κB2. We uncovered a vesicle-mediated platelet-monocyte-propagation of inflammatory transcription regulators, positioning platelets as central checkpoints in monocyte inflammation.

Autophagy-mediated activation of the AIM2 inflammasome enhances M1 polarization of microglia and exacerbates retinal neovascularization.

Retinopathy of prematurity (ROP) is a retinal neovascularization (RNV) disease that is characterized by abnormal blood vessel development in the retina. Importantly, the etiology of ROP remains understudied. We re-analyzed previously published single-cell data and discovered a strong correlation between microglia and RNV diseases, particularly ROP. Subsequently, we found that reactive oxygen species reduced autophagy-dependent protein degradation of absent in melanoma 2 (AIM2) in hypoxic BV2 cells, leading to increased AIM2 protein accumulation. Furthermore, we engineered AIM2 knockout mice and observed that the RNV was significantly reduced compared to wild-type mice. In vitro vascular function assays also demonstrated diminished angiogenic capabilities following AIM2 knockdown in hypoxic BV2 cells. Mechanistically, AIM2 enhanced the M1-type polarization of microglia via the ASC/CASP1/IL-1ß pathway, resulting in RNV. Notably, the administration of recombinant protein IL-1ß exacerbated angiogenesis, while its inhibition ameliorated the condition. Taken together, our study provides a novel therapeutic target for ROP and offers insight into the interaction between pyroptosis and autophagy.

miR-483-5p-Containing exosomes treatment ameliorated deep vein thrombosis­induced inflammatory response.

Peripheral vascular condition, known as deep vein thrombosis (DVT), is a common ailment that may lead to deadly pulmonary embolism. Inflammation is closely connected to venous thrombosis, which results in blood stasis, leading to ischemia and hypoxia, as indicated by research. The objective of this research was to investigate the mechanism by which exosomes derived from adipose stem cells (ADSCs) prevent deep vein thrombosis. Our data showed that Exo-483 effectively reduced the thrombus weight in DVT rats by intravenous injection. Exo-483 decreased the expression of tissue factor (TF) protein, the influx of inflammatory cells into the thrombosed vein wall, and the levels of cytokines in the serum. Furthermore, Exo-483 suppressed the expression of Mitogen-activated protein kinase 1 (MAPK1) and decreased the expression of NLRP3 inflammasomes. In an oxygen-glucose deprivation (OGD) cell model, the tube-forming and migratory abilities of primary human umbilical vein endothelial cells (HUVEC) and EA.hy926 cells were suppressed by Exo-483 pretreatment.Exo-483 is also linked to regulating Dynamin-related protein 1 (DRP1) production downstream of MAPK1.By decreasing the mitochondrial localization and phosphorylation at the S616 site of DRP1, it diminishes the expression of NLRP3 inflammasomes. Moreover, according to Bioinformatics analysis, miR-483-5p was anticipated to target MAPK1. The research conducted by our team revealed that the miR-483-5p exosome derived from ADSCs exhibited anti-inflammatory properties through the modulation of downstream DRP1-NLRP3 expression by targeting MAPK1.The findings of this research propose that miR-483-5p may be regarded as an innovative treatment target for DVT.