Diverse Activators of the NLRP3 Inflammasome Promote IL-1β Secretion by Triggering Necrosis

Sodium butyrate alleviates colitis by inhibiting mitochondrial ROS mediated macrophage pyroptosis

Inflammatory bowel disease (IBD) is a chronic inflammatory bowel disease with unclear causes and limited treatment options. Sodium butyrate (NaB), a byproduct of dietary fiber in the intestine, has demonstrated efficacy in treating inflammation. However, the precise anti-inflammatory mechanisms of NaB in colon inflammation remain largely unexplored. This study aims to investigate the effects of NaB on dextran sulfate sodium (DSS)-induced colitis in rats. The findings indicate that oral administration of NaB effectively prevent colitis and reduce levels of serum or colon inflammatory factors. Additionally, NaB demonstrated in vitro inhibition of RAW264.7 inflammation cytokines induced by LPS, along with suppression of the ERK and NF-κB signaling pathway activation. Moreover, NaB mitigated LPS and Nigericin-induced RAW264.7 pyroptosis by reducing indicators of mitochondrial damage, including increased mitochondrial membrane potential (JC-1) levels and decreased Mito-ROS production. NaB increases ZO-1 and Occludin expression in CaCo2 cells by inhibiting RAW264.7 pyroptosis. These results suggest that NaB could be utilized as a therapeutic agent or dietary supplement to alleviate colitis.

MiR-146a engineered extracellular vesicles derived from mesenchymal stromal cells more potently attenuate ischaemia-reperfusion injury in lung transplantation

BACKGROUND

The limited donor lung pool for lung transplantation (LTx) is largely due to concerns over ischaemia-reperfusion injury (IRI), a major cause of primary graft dysfunction (PGD). NLRP3 inflammasome activation is known to play a pivotal role in the onset of IRI. While human umbilical cord mesenchymal stromal cell-derived extracellular vesicles (hucMSC-EVs) have shown potential in reducing acute lung injury, their effects on NLRP3 activation in the context of LTx remain unclear.

METHODS

In this study, engineered hucMSC-EVs were delivered via nebulisation to mitigate IRI in rat LTx models. We utilised both a rat orthotopic LTx model and a cell cold preservation reperfusion model to evaluate the therapeutic efficacy of hucMSC-EVs. Bulk-RNA sequencing, single-cell sequencing analysis, immunofluorescence and Western blot techniques were employed to assess NLRP3 inflammasome activation and inflammation.

RESULTS

Nebulised hucMSC-EVs were efficiently internalised by alveolar macrophages (AMs), significantly reducing lung injury and improving oxygenation in the LTx models. Mechanistically, the engineered hucMSC-EVs, which enhance the expression of miR-146a, can more effectively suppress the activation of the NLRP3 inflammasome by targeting the IRAK1/TRAF6/NF-κB pathway, resulting in decreased levels of IL-1β, IL-18 and other inflammatory cytokines. These findings highlight the potential of miR-146a-modified EVs in modulating innate immune responses to alleviate IRI.

CONCLUSION

Our results demonstrate that nebulised delivery of engineered hucMSC-EVs effectively mitigates IRI in LTx by inhibiting NLRP3 inflammasome activation. This innovative approach presents a promising strategy for enhancing donor lung preservation and improving post-transplant outcomes in LTx.

HIGHLIGHTS

Nebulized Delivery of miR-146a Engineered hucMSC-EVs Mitigates Ischemia-Reperfusion Injury (IRI) in Lung Transplantation. This study demonstrates the therapeutic potential of nebulized, engineered human umbilical cord mesenchymal stromal cell-derived extracellular vesicles (hucMSC-EVs) modified with miR-146a to alleviate IRI in rat lung transplantation models. The treatment significantly improved lung oxygenation and reduced inflammation, highlighting the efficacy of this novel approach in enhancing donor lung preservation. Mechanistic Insights: Inhibition of NLRP3 Inflammasome Activation. Engineered hucMSC-EVs efficiently targeted alveolar macrophages and suppressed NLRP3 inflammasome activation through the IRAK1/TRAF6/NF-κB pathway. This modulation of innate immune responses played a crucial role in reducing IRI-induced lung injury and inflammation, offering a promising strategy to manage primary graft dysfunction in lung transplantation. Superior Efficacy of miR-146a-Modified EVs in Reducing Inflammatory Cytokines. The miR-146a modification enhanced the anti-inflammatory properties of hucMSC-EVs, leading to a more significant reduction in pro-inflammatory cytokines (IL-1β, IL-18, and TNF-α) compared to unmodified EVs. This targeted intervention presents a potential therapeutic avenue for improving lung transplant outcomes and mitigating IRI. Innovative Therapeutic Approach: Non-Invasive Nebulization for Direct Lung Delivery. The use of nebulized EVs for direct delivery to donor lungs represents a non-invasive and efficient method for lung-targeted therapy. This strategy could expand the applicability of MSC-EV-based treatments for improving lung transplantation outcomes, particularly in enhancing donor lung preservation during the procurement process.

The Emerging Role of Colchicine to Inhibit NOD-like Receptor Family, Pyrin Domain Containing 3 Inflammasome and Interleukin-1β Expression in In Vitro Models

While the beneficial effects of colchicine on inflammation and infarcted myocardium have been documented, its impact on cardiac fibroblast activation in the context of myocardial infarction (MI) remains unknown. This study aimed to investigate the effect of colchicine on the regulation of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation and Interleukin-1β (IL-1β) expression in fibroblasts. 3T3 fibroblasts were exposed to 600 μM CoCl2 for 24 h to simulate hypoxia, with normoxic cells as controls. Colchicine (1 μM) was administered for 24 h. ASC-NLRP3 colocalization and IL-1β expression were evaluated using immunofluorescence and flow cytometry, respectively. Data were analyzed using t-tests and one-way ANOVA with post hoc tests. Hypoxia treatment significantly induced apoptosis-associated speck-like protein containing a CARD (ASC)-NLRP3 colocalization (p < 0.05). Colchicine treatment of hypoxic 3T3 cells reduced ASC-NLRP3 colocalization, although this reduction was not statistically significant. Additionally, IL-1β expression was significantly inhibited in colchicine-treated hypoxic 3T3 cells compared to those treated with placebo (p < 0.05). The findings of this study indicate that colchicine treatment inhibits the activation of the NLRP3 inflammasome by disrupting the colocalization of ASC and NLRP3, thereby reducing IL-1β expression in CoCl2-treated 3T3 cells.

The vasoconstrictor adenosine 5'-tetraphosphate is a danger signal that induces IL-1β

BACKGROUND

The endogenous nucleotide adenosine 5'-tetraphosphate (Ap4) is a potent vasoconstrictor. Despite its structural similarity to the danger signal adenosine 5'-triphosphate (ATP), the immunomodulatory effects of Ap4 remain unclear.

METHODS

Modulation of interleukin (IL)-1β secretion by Ap4 was studied in both immune cells lines (THP-1, U937) and primary immune cells. Genetic and pharmacological approaches were used to characterize signaling. Cytokine production was measured using ELISA and multiplex assays, while cell viability was determined by MTT and LDH assays. Calcium influx and YO-PRO-1 uptake were assessed via microplate assays and flow cytometry, respectively. RNA sequencing and Western blotting were performed to analyze global gene expression and protein levels.

RESULTS

We demonstrate that Ap4 stimulates IL-1β release in primed immune cells without affecting the levels of other cytokines, suggesting specificity in its immunomodulatory actions. Mechanistically, Ap4-induced IL-1β release was partially modulated by the P2X7 receptor, a key mediator of inflammation. However, unlike canonical inflammasome activators, this process was independent of potassium efflux, the NLRP3 inflammasome, and caspase-1. Ap4 specifically increased LDH release in macrophages irrespective of priming. Furthermore, Ap4-mediated calcium influx, crucial for immune cell activation, predominantly occurred through P2Y receptors rather than P2X7 receptors. Transcriptomic analysis highlighted Ap4-induced upregulation of metallothioneins, implicating metal ion homeostasis in Ap4-mediated responses.

CONCLUSIONS

Collectively, our findings suggest Ap4 as a novel pro-inflammatory mediator capable of inducing IL-1β release in innate immune cells through distinct mechanisms from classical NLRP3 inflammasome activators, shedding light on its potential role in inflammatory diseases and vascular disorders.

Mechanism of effect and therapeutic potential of NLRP3 inflammasome in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury that can trigger various neuropathological conditions, resulting in neuronal damage and release of various pro-inflammatory mediators, leading to neurological dysfunction. Currently, surgical decompression, drugs and rehabilitation are primarily used to relieve symptoms and improve endogenous repair mechanisms; however, they cannot directly promote nerve regeneration and functional recovery. SCI can be divided into primary and secondary injuries. Secondary injury is key to determining the severity of injury, whereas inflammation and cell death are important pathological mechanisms in the process of secondary SCI. The activation of the inflammasome complex is thought to be a necessary step in neuro-inflammation and a key trigger for neuronal death. The NLRP3 inflammasome is a cytoplasmic multiprotein complex that is considered an important factor in the development of SCI. Once the NLRP3 inflammasome is activated after SCI, NLRP3 nucleates the assembly of an inflammasome, leading to caspase 1-mediated proteolytic activation of the interleukin-1β (IL-1β) family of cytokines, and induces an inflammatory, pyroptotic cell death. Inhibition of inflammasomes can effectively inhibit inflammation and cell death in the body and promote the recovery of nerve function after SCI. Therefore, inhibition of NLRP3 inflammasome activation may be a promising approach for the treatment of SCI. In this review, we describe the current understanding of NLRP3 inflammasome activation in SCI pathogenesis and its subsequent impact on SCI and summarize drugs and other potential inhibitors based on NLRP3 inflammasome regulation. The objective of this study was to emphasize the role of the NLRP3 inflammasome in SCI, and provide a new therapeutic strategy and theoretical basis for targeting the NLRP3 inflammasome as a therapy for SCI.

Interleukin 1β receptor and synaptic dysfunction in recurrent brain infection with Herpes simplex virus type-1

Several experimental evidence suggests a link between brain Herpes simplex virus type-1 infection and the occurrence of Alzheimer's disease. However, the molecular mechanisms underlying this association are not completely understood. Among the molecular mediators of synaptic and cognitive dysfunction occurring after Herpes simplex virus type-1 infection and reactivation in the brain neuroinflammatory cytokines seem to occupy a central role. Here, we specifically reviewed literature reports dealing with the impact of neuroinflammation on synaptic dysfunction observed after recurrent Herpes simplex virus type-1 reactivation in the brain, highlighting the role of interleukins and, in particular, interleukin 1β as a possible target against Herpes simplex virus type-1-induced neuronal dysfunctions.

NLRP3 Inflammasome Upregulates PD-L1 in Ovarian Cancer and Contributes to an Immunosuppressive Microenvironment

Introduction

The NLRP3 inflammasome has been implicated in the initiation of inflammation and tumorigenesis; however, its role in epithelial ovarian cancer (EOC) remains unclear.

Methods

This study employed high-throughput sequencing data, ELISA, clone formation assay, Western blot, and flow cytometric analysis to investigate the specific role of the NLRP3 inflammasome in EOC.

Results

NLRP3 was highly expressed in human EOC tissues and correlated with an unfavorable prognosis. Activation of the NLRP3 inflammasome by LPS and ATP promoted EOC cell proliferation and increased IL-1 and PD-L1 levels. MCC950, a NLRP3 inflammasome blocker, reduced IL-1 and PD-L1 levels and diminished tumor-immune suppressive cells, such as myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and PD-1+ CD4+ T cells, in a murine model of ovarian cancer. This intervention also suppressed tumor growth.

Conclusion

Our investigation revealed the pro-tumorigenic role of the NLRP3 inflammasome and its regulation of PD-L1 expression in EOC. Blockade of the NLRP3 inflammasome led to reduced PD-L1 expression, fewer immunosuppressive cells, and suppressed tumor growth. These findings suggest that targeting the NLRP3 inflammasome-PD-L1 axis could be a novel treatment approach for ovarian cancer.

Poly(allylamine)/tripolyphosphate nanocomplex coacervate as a NLRP3-dependent systemic adjuvant for vaccine development

Nanotechnology plays a crucial role in vaccine development. It allows the design of functional nanoparticles (NPs) that can act both as antigen carriers and as adjuvants to enhance the immune response. The present study aims to evaluate complex coacervate-like NPs composed of poly(allylamine hydrochloride) (PAH) and tripolyphosphate (TPP) as a safe vehicle and adjuvant for systemic vaccines. We investigated the activation of different antigen-presenting cells (APCs) with NPs and their adjuvanticity in Balbc/c and different KO mice that were intraperitoneally immunized with NP-OVA. We found that NPs increased the expression of CD86 and MHCII and promoted the production and secretion of interleukin-1β (IL-1β) and IL-18 through the inflammasome NLRP3 when macrophages and dendritic cells were co-incubated with LPS and NPs. We evidenced an unconventional IL-1β release through the autophagosome pathway. The inhibition of autophagy with 3-methyladenine reduced the LPS/NPs-induced IL-1β secretion. Additionally, our findings showed that the systemic administration of mice with NP-OVA triggered a significant induction of serum OVA-specific IgG and IgG2a, an increased secretion of IFN-γ by spleen cells, and high frequencies of LT CD4 + IFN-γ + and LT CD8 + IFN-γ + . Our findings show that NPs promoted the inflammasome activation of innate cells with Th1-dependent adjuvant properties, making them valuable for formulating novel preventive or therapeutic vaccines for infectious and non-infectious diseases.

Type I IFN drives unconventional IL-1β secretion in lupus monocytes

Opsonization of red blood cells that retain mitochondria (Mito+ RBCs), a feature of systemic lupus erythematosus (SLE), triggers type I interferon (IFN) production in macrophages. We report that monocytes (Mos) co-produce IFN and mature interleukin-1β (mIL-1β) upon Mito+ RBC opsonization. IFN expression depended on cyclic GMP-AMP synthase (cGAS) and RIG-I-like receptors' (RLRs) sensing of Mito+ RBC-derived mitochondrial DNA (mtDNA) and mtRNA, respectively. Interleukin-1β (IL-1β) production was initiated by the RLR antiviral signaling adaptor (MAVS) pathway recognition of Mito+ RBC-derived mtRNA. This led to the cytosolic release of Mo mtDNA, which activated the inflammasome. Importantly, mIL-1β secretion was independent of gasdermin D (GSDMD) and pyroptosis but relied on IFN-inducible myxovirus-resistant protein 1 (MxA), which facilitated the incorporation of mIL-1β into a trans-Golgi network (TGN)-mediated secretory pathway. RBC internalization identified a subset of blood Mo expressing IFN-stimulated genes (ISGs) that released mIL-1β and expanded in SLE patients with active disease.

Portulaca Oleracea L. Phenolic Amide Methyl (3,4,5-Trimethoxybenzoyl) Valylprolinate Attenuates Diethylhexyl Phthalate-Induced Human Umbilical Vein Endothelial Cells' Inflammation Through NLRP3 and NF-κB Pathways

Twelve polyphenol derivatives were obtained in a protective activity-guided isolation from the Portulaca oleracea L. extract on a cell model of human umbilical vein endothelial cells (HUVECs) under diethylhexyl phthalate (DEHP) exposure. Among them, methyl (3,4,5-trimethoxybenzoyl) valylprolinate (PP-10) performed the most protective activity and inhibited DEHP exposure-induced HUVECs' apoptosis. PP-10 also inhibited the DEHP-induced inflammatory cytokines (TNF-α, IL-6, IL-1β, and IL-8) and adhesion molecule (ICAM-1 andVCAM-1) overexpression. Furthermore, DEHP-induced NLRP3 inflammasomes' and NF-κB signaling pathway activation was significantly inhibited after the PP-10 treatments. Of note, the current results suggest the potential application of Portulaca oleracea L. and PP-10 in the prevention of DEHP-induced inflammatory damages in HUVECs.

Microglial NLRP3 inflammasome-mediated neuroinflammation and therapeutic strategies in depression

Previous studies have demonstrated a bidirectional relationship between inflammation and depression. Activation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and NLR family pyrin domain-containing 3 (NLRP3) inflammasomes is closely related to the pathogenesis of various neurological diseases. In patients with major depressive disorder, NLRP3 inflammasome levels are significantly elevated. Understanding the role that NLRP3 inflammasome-mediated neuroinflammation plays in the pathogenesis of depression may be beneficial for future therapeutic strategies. In this review, we aimed to elucidate the mechanisms that lead to the activation of the NLRP3 inflammasome in depression as well as to provide insight into therapeutic strategies that target the NLRP3 inflammasome. Moreover, we outlined various therapeutic strategies that target the NLRP3 inflammasome, including NLRP3 inflammatory pathway inhibitors, natural compounds, and other therapeutic compounds that have been shown to be effective in treating depression. Additionally, we summarized the application of NLRP3 inflammasome inhibitors in clinical trials related to depression. Currently, there is a scarcity of clinical trials dedicated to investigating the applications of NLRP3 inflammasome inhibitors in depression treatment. The modulation of NLRP3 inflammasomes in microglia holds promise for the management of depression. Further investigations are necessary to ascertain the efficacy and safety of these therapeutic approaches as potential novel antidepressant treatments.

Emerging role of galectin 3 in neuroinflammation and neurodegeneration

Neuroinflammation and neurodegeneration are key processes that mediate the development and progression of neurological diseases. However, the mechanisms modulating these processes in different diseases remain incompletely understood. Advances in single cell based multi-omic analyses have helped to identify distinct molecular signatures such as Lgals3 that is associated with neuroinflammation and neurodegeneration in the central nervous system (CNS). Lgals3 encodes galectin-3 (Gal3), a β-galactoside and glycan binding glycoprotein that is frequently upregulated by reactive microglia/macrophages in the CNS during various neurological diseases. While Gal3 has previously been associated with non-CNS inflammatory and fibrotic diseases, recent studies highlight Gal3 as a prominent regulator of inflammation and neuroaxonal damage in the CNS during diseases such as multiple sclerosis, Alzheimer's disease, and Parkinson's disease. In this review, we summarize the pleiotropic functions of Gal3 and discuss evidence that demonstrates its detrimental role in neuroinflammation and neurodegeneration during different neurological diseases. We also consider the challenges of translating preclinical observations into targeting Gal3 in the human CNS.

Exploring the potential molecular intersection of stroke and major depression disorder

Stroke and major depression disorder are common neurological diseases, and a large number of clinical studies have shown that there is a close relationship between the two diseases, but whether the two diseases are linked at the genetic level needs to be further explored. The purpose of this study was to explore the comorbidity mechanism of stroke and major depression by using bioinformatics technology and animal experiments. From the GEO database, we gathered transcriptome data of stroke and depression mice (GSE104036, GSE131712, GSE81672, and GSE146845) and identified comorbid gene set through edgR and WGCNA analyses. Further analysis revealed that these genes were enriched in pathways associated with cell death. Programmed cell death gene sets (PCDGs) are generated from genes related to apoptosis, necroptosis, pyroptosis and autophagy. The intersection of PCDGs and comorbid gene set resulted in two hub genes, Mlkl and Nlrp3. Single-cell sequencing analysis indicated that Mlkl and Nlrp3 are mainly influential on endothelial cells and microglia, suggesting that the impairment of these two cell types may be a factor in the relationship between stroke and major depression. This was experimentally confirmed by RT-PCR and immunofluorescence staining. Our research revealed that two specific genes, namely, Mlkl and Nlrp3, play crucial roles in the complex mechanism that links stroke and major depression. Additionally, we have predicted six possible therapeutic agents and the outcomes of docking simulations of target proteins and drug molecules.

Developing an in vitro model of haematoma for study of intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a devastating neurovascular attack with limited treatment options. Alternative, pre-clinical modelling approaches are required to identify and trial therapeutic drug compounds. In this study we have used alginate hydrogels to model blood insult in vitro. Human whole blood was mixed with alginate and encapsulated into hydrogel beads. Beads were then incorporated in a second layer of alginate containing hyaluronic acid/chitosan nanoparticles to mimic the mechanical properties of brain tissue and create a model haematoma. Beads and model haematomas were characterised to profile size, volume, mechanical properties, release capacity and storage stability over time. Beads and model haematomas stimulate a pro-inflammatory phenotype in human monocytic and macrophage-like cells, however have no pathogenic effect on brain endothelial and neuronal cell survival or function. In conclusion, we have developed an effective strategy to model ICH in vitro, to investigate the human immune response to blood insult.

Antioxidant and Anti-Inflammatory Properties of Hydrolyzed Royal Jelly Peptide in Human Dermal Fibroblasts: Implications for Skin Health and Care Applications

Hydrolyzed royal jelly peptide (RJP) has garnered attention for its health-promoting functions. However, the potential applications of RJP in skincare have not been fully explored. In this study, we prepared RJP through the enzymatic hydrolysis of royal jelly protein with trypsin and investigated its antioxidant and anti-inflammatory properties on primary human dermal fibroblasts (HDFs). Our results demonstrate that RJP effectively inhibits oxidative damage induced by H2O2 and lipid peroxidation triggered by AAPH and t-BuOOH in HDFs. This effect may be attributed to the ability of RJP to enhance the level of glutathione and the activities of catalase and glutathione peroxidase 4, as well as its excellent iron chelating capacity. Furthermore, RJP modulates the NLRP3 inflammasome-mediated inflammatory response in HDFs, suppressing the mRNA expressions of NLRP3 and IL-1β in the primer stage induced by LPS and the release of mature IL-1β induced by ATP, monosodium urate, or nigericin in the activation stage. RJP also represses the expressions of COX2 and iNOS induced by LPS. Finally, we reveal that RJP exhibits superior antioxidant and anti-inflammatory properties over unhydrolyzed royal jelly protein. These findings suggest that RJP exerts protective effects on skin cells through antioxidative and anti-inflammatory mechanisms, indicating its promise for potential therapeutic avenues for managing oxidative stress and inflammation-related skin disorders.

Extracellular ATP contributes to the reactive oxygen species burst and exaggerated mitochondrial damage in D-galactosamine and lipopolysaccharide-induced fulminant hepatitis

Fulminant hepatitis (FH) is a severe clinical syndrome leading to hepatic failure and even mortality. D-galactosamine (D-GalN) plus lipopolysaccharide (LPS) challenge is commonly used to establish an FH mouse model, but the mechanism underlying D-GalN/LPS-induced liver injury is incompletely understood. Previously, it has been reported that extracellular ATP that can be released under cytotoxic and inflammatory stresses serves as a damage signal to induce potassium ion efflux and trigger the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome activation through binding to P2X7 receptor. In this study, we tried to investigate whether it contributed to the fulminant hepatitis (FH) induced by D-GalN plus LPS. In an in vitro cellular model, D-GalN plus extracellular ATP, instead of D-GalN alone, induced pyroptosis and apoptosis, accompanied by mitochondrial reactive oxygen species (ROS) burst, and the oligomerization of Drp1, Bcl-2, and Bak, as well as the loss of mitochondrial membrane potential in LPS-primed macrophages, well reproducing the events induced by D-GalN and LPS in vivo. Moreover, these events in the cellular model were markedly suppressed by both A-804598 (an ATP receptor P2X7R inhibitor) and glibenclamide (an ATP-sensitive potassium ion channel inhibitor); in the FH mouse model, administration of A-804598 significantly mitigated D-GalN/LPS-induced hepatic injury, mitochondrial damage, and the activation of apoptosis and pyroptosis signaling, corroborating the contribution of extracellular ATP to the cell death. Collectively, our data suggest that extracellular ATP acts as an autologous damage-associated molecular pattern to augment mitochondrial damage, hepatic cell death, and liver injury in D-GalN/LPS-induced FH mouse model.

Cancer-derived exosomal Alu RNA promotes colorectal cancer progression

Inflammation plays a crucial role in cancer progression, but the relevance of the inflammasome remains unclear. Alu RNA was the first endogenous nucleic acid shown to activate the NLRP3 (nucleotide-binding domain leucine-rich repeat containing 3) inflammasome. Here, we showed that Alu RNA can induce epithelial-to-mesenchymal transition (EMT) through NLRP3 inflammasome activation and IL-1β release in colorectal cancer (CRC) cells. Alu RNA is stored, transported and transferred to CRC cells by exosomes. Exosomal Alu RNA promotes tumorigenesis by inducing invasion, metastasis and EMT via NLRP3 inflammasome activation. Consistent with these data, we found that significantly increased Alu RNA expression correlates with the induction of NLRP3 priming in human CRC patients. Furthermore, the level of Alu RNA in circulating exosomes correlates with CRC progression in a preclinical model. These findings reveal the direct involvement of Alu RNA in cancer pathogenesis, and its presence in CRC cell-derived exosomes could be used as a noninvasive diagnostic biomarker.

Potassium ion efflux induces exaggerated mitochondrial damage and non-pyroptotic necrosis when energy metabolism is blocked

Damage-associated molecular patterns (DAMPs) such as extracellular ATP and nigericin (a bacterial toxin) not only act as potassium ion (K+) efflux inducers to activate NLRP3 inflammasome, leading to pyroptosis, but also induce cell death independently of NLRP3 expression. However, the roles of energy metabolism in determining NLRP3-dependent pyroptosis and -independent necrosis upon K+ efflux are incompletely understood. Here we established cellular models by pharmacological blockade of energy metabolism, followed by stimulation with a K+ efflux inducer (ATP or nigericin). Two energy metabolic inhibitors, namely CPI-613 that targets α-ketoglutarate dehydrogenase and pyruvate dehydrogenase (a rate-limiting enzyme) and 2-deoxy-d-glucose (2-DG) that targets hexokinase, are recruited in this study, and Nlrp3 gene knockout macrophages were used. Our data showed that CPI-613 and 2-DG dose-dependently inhibited NLRP3 inflammasome activation, but profoundly increased cell death in the presence of ATP or nigericin. The cell death was K+ efflux-induced but NLRP3-independent, which was associated with abrupt reactive oxygen species (ROS) production, reduction of mitochondrial membrane potential, and oligomerization of mitochondrial proteins, all indicating mitochondrial damage. Notably, the cell death induced by K+ efflux and blockade of energy metabolism was distinct from pyroptosis, apoptosis, necroptosis or ferroptosis. Furthermore, fructose 1,6-bisphosphate, a high-energy intermediate of glycolysis, significantly suppressed CPI-613+nigericin-induced mitochondrial damage and cell death. Collectively, our data show that energy deficiency diverts NLRP3 inflammasome activation-dependent pyroptosis to Nlrp3-independent necrosis upon K+ efflux inducers, which can be dampened by high-energy intermediate, highlighting a critical role of energy metabolism in cell survival and death under inflammatory conditions.

TNFα modulates PANX1 activation to promote ATP release and enhance P2RX7-mediated antitumor immune responses after chemotherapy in colorectal cancer

ATP and its receptor P2RX7 exert a pivotal effect on antitumor immunity during chemotherapy-induced immunogenic cell death (ICD). Here, we demonstrated that TNFα-mediated PANX1 cleavage was essential for ATP release in response to chemotherapy in colorectal cancer (CRC). TNFα promoted PANX1 cleavage via a caspase 8/3-dependent pathway to enhance cancer cell immunogenicity, leading to dendritic cell maturation and T-cell activation. Blockade of the ATP receptor P2RX7 by the systemic administration of small molecules significantly attenuated the therapeutic efficacy of chemotherapy and decreased the infiltration of immune cells. In contrast, administration of an ATP mimic markedly increased the therapeutic efficacy of chemotherapy and enhanced the infiltration of immune cells in vivo. High PANX1 expression was positively correlated with the recruitment of DCs and T cells within the tumor microenvironment and was associated with favorable survival outcomes in CRC patients who received adjuvant chemotherapy. Furthermore, a loss-of-function P2RX7 mutation was associated with reduced infiltration of CD8+ immune cells and poor survival outcomes in patients. Taken together, these results reveal that TNFα-mediated PANX1 cleavage promotes ATP-P2RX7 signaling and is a key determinant of chemotherapy-induced antitumor immunity.

Pyroptosis in septic lung injury: Interactions with other types of cell death

Sepsis is a life-threatening systemic inflammatory response syndrome caused by the host imbalanced response to infection. Lung injury is the most common complication of sepsis and one of the leading causes of patient death. Pyroptosis is a specific programmed cell death characterized by the release of inflammatory cytokines. Appropriate pyroptosis can reduce tissue damage and exert a protective effect against infection during sepsis. However, overactivated pyroptosis results in massive cell death, leading to septic shock, multiple organ dysfunction syndrome, and even an increased risk of secondary infection. Recent studies suggest that pyroptosis can interact with and cross-regulate other types of cell death programs to establish a complex network of cell death, which participates in the occurrence and development of septic lung injury. This review will focus on the interactions between pyroptosis and other types of cell death, including apoptosis, necroptosis, PANoptosis, NETosis, autophagy, and ferroptosis, to summarize the role of pyroptosis in sepsis-induced lung injury, and will discuss the potential therapeutic strategies of targeting pyroptosis during sepsis treatment.

Sertraline associated with gold nanoparticles reduce cellular toxicity and induce sex-specific responses in behavior and neuroinflammation biomarkers in a mouse model of anxiety

This study aimed to evaluate the effects of sertraline associated with gold nanoparticles (AuNPs) in vitro cell viability and in vivo behavior and inflammatory biomarkers in a mouse model of anxiety. Sertraline associated with AuNPs were synthesized and characterized. For the in vitro study, NIH3T3 and HT-22 cells were treated with different doses of sertraline, AuNPs, and sertraline + AuNPs and their viability was evaluated using the MTT assay. For the in vivo study, pregnant Swiss mice were administered a single dose of lipopolysaccharide (LPS) on the ninth day of gestation. The female and male offspring were divided into five treatment groups on PND 60 and administered chronic treatment for 28 days. The animals were subjected to behavioral testing and were subsequently euthanized. Their brains were collected and analyzed for inflammatory biomarkers. Sertraline associated with AuNPs exhibited significant changes in surface characteristics and increased diameters. Different doses of sertraline + AuNPs showed higher cell viability in NIH3T3 and HT-22 cells compared with sertraline alone. The offspring of LPS-treated dams exhibited anxiety-like behavior and neuroinflammatory biomarker changes during adulthood, which were ameliorated via sertraline + AuNPs treatment. The treatment response was sex-dependent and brain region-specific. These results suggest that AuNPs, which demonstrate potential to bind to other molecules, low toxicity, and reduced inflammation, can be synergistically used with sertraline to improve drug efficacy and safety by decreasing neuroinflammation and sertraline toxicity.

A detailed molecular network map and model of the NLRP3 inflammasome

The NLRP3 inflammasome is a key regulator of inflammation that responds to a broad range of stimuli. The exact mechanism of activation has not been determined, but there is a consensus on cellular potassium efflux as a major common denominator. Once NLRP3 is activated, it forms high-order complexes together with NEK7 that trigger aggregation of ASC into specks. Typically, there is only one speck per cell, consistent with the proposal that specks form - or end up at - the centrosome. ASC polymerisation in turn triggers caspase-1 activation, leading to maturation and release of IL-1β and pyroptosis, i.e., highly inflammatory cell death. Several gain-of-function mutations in the NLRP3 inflammasome have been suggested to induce spontaneous activation of NLRP3 and hence contribute to development and disease severity in numerous autoinflammatory and autoimmune diseases. Consequently, the NLRP3 inflammasome is of significant clinical interest, and recent attention has drastically improved our insight in the range of involved triggers and mechanisms of signal transduction. However, despite recent progress in knowledge, a clear and comprehensive overview of how these mechanisms interplay to shape the system level function is missing from the literature. Here, we provide such an overview as a resource to researchers working in or entering the field, as well as a computational model that allows for evaluating and explaining the function of the NLRP3 inflammasome system from the current molecular knowledge. We present a detailed reconstruction of the molecular network surrounding the NLRP3 inflammasome, which account for each specific reaction and the known regulatory constraints on each event as well as the mechanisms of drug action and impact of genetics when known. Furthermore, an executable model from this network reconstruction is generated with the aim to be used to explain NLRP3 activation from priming and activation to the maturation and release of IL-1β and IL-18. Finally, we test this detailed mechanistic model against data on the effect of different modes of inhibition of NLRP3 assembly. While the exact mechanisms of NLRP3 activation remains elusive, the literature indicates that the different stimuli converge on a single activation mechanism that is additionally controlled by distinct (positive or negative) priming and licensing events through covalent modifications of the NLRP3 molecule. Taken together, we present a compilation of the literature knowledge on the molecular mechanisms on NLRP3 activation, a detailed mechanistic model of NLRP3 activation, and explore the convergence of diverse NLRP3 activation stimuli into a single input mechanism.

Kurarinone exerts anti-inflammatory effect via reducing ROS production, suppressing NLRP3 inflammasome, and protecting against LPS-induced sepsis

Kurarinone, a major lavandulyl flavanone found in the roots of Sophora flavescens aiton, has been reported to exhibit anti-inflammatory and anti-oxidative activities in lipopolysaccharide (LPS)-induced macrophages; however, the effects of kurarinone on the activation of NLRP3 inflammasome and the protective effects against sepsis have not been well investigated. In this study, we aimed to investigate the impacts of kurarinone on NLRP3 inflammasome activation in lipopolysaccharide (LPS)-induced macrophages and its protective effects against sepsis in vivo. Secretion of pro-inflammatory cytokines, activation of MAPKs and NF-κB signaling pathways, formation of NLRP3 inflammasome, and production of reactive oxygen species (ROS) by LPS-induced macrophages were examined; additionally, in vivo LPS-induced endotoxemia model was used to investigate the protective effects of kurarinone in sepsis-induced damages. Our experimental results demonstrated that kurarinone inhibited the expression of iNOS and COX-2, suppressed the phosphorylation of MAPKs, attenuated the production of TNF-α, IL-6, nitric oxide (NO) and ROS, repressed the activation of the NLRP3 inflammasome, and impeded the maturation and secretion of IL-1β and caspase-1. Furthermore, the administration of kurarinone attenuated the infiltration of neutrophils in the lung, kidneys and liver, reduced the expression of organ damage markers, and increased the survival rate in LPS-challenged mice. Collectively, our study demonstrated that kurarinone can protect against LPS-induced sepsis damage and exert anti-inflammatory effects via inhibiting MAPK/NF-κB pathways, attenuating NLRP3 inflammasome formation, and preventing intracellular ROS accumulation, suggesting that kurarinone might have potential for treating sepsis and inflammation-related diseases.

Construction of PANoptosis signature: Novel target discovery for prostate cancer immunotherapy

PANoptosis pathway gene sets encompassing pyroptosis, apoptosis, and necroptosis were identified from the MSigDB database. We analyzed the perturbations and crosstalk in the PANoptosis pathway in prostate adenocarcinoma (PRAD), including gene mutation, transcription, methylation, and clinical features. By constructing a PANoptosis signature, we accurately predicted the prognosis and immunotherapeutic response of PRAD patients. We further explored the molecular features and immunological roles of the signature, dividing patients into high- and low-score groups. Notably, the high-score group correlated with better survival outcomes and immunotherapeutic responses, as well as a higher mutation frequency and enrichment score in the PANoptosis and HALLMARK pathways. The PANoptosis signature also enhanced overall antitumor immunity, promoted immune cell infiltration, upregulated immune checkpoint regulators, and revealed the cold tumor characteristics of PRAD. We also identified potential drug targets based on the PANoptosis signature. These findings lead the way in identifying novel prognostic markers and therapeutic targets for patients with PRAD.

An unconventional mechanism of IL-1β secretion that requires Type I IFN in lupus monocytes

Systemic Lupus Erythematosus (SLE) is characterized by autoreactive B cell activation, upregulation of Type I Interferon (IFN) and widespread inflammation. Mitochondrial nucleic acids (NAs) are increasingly recognized as triggers of IFN 1 . Thus, defective removal of mitochondria from mature red blood cells (Mito + RBCs), a feature of SLE, contributes to IFN production by myeloid cells 2 . Here we identify blood monocytes (Mo) that have internalized RBCs and co-express IFN-stimulated genes (ISGs) and interleukin-1β (IL-1β) in SLE patients with active disease. We show that ISG expression requires the interaction between Mito + RBC-derived mitochondrial DNA (mtDNA) and cGAS, while IL-1β production entails Mito + RBC-derived mitochondrial RNA (mtRNA) triggering of RIG-I-like receptors (RLRs). This leads to the cytosolic release of Mo-derived mtDNA that activates the NLRP3 inflammasome. Importantly, IL-1β release depends on the IFN-inducible myxovirus resistant protein 1 (MxA), which enables the translocation of this cytokine into a trans-Golgi network (TGN)-mediated unconventional secretory pathway. Our study highlights a novel and synergistic pathway involving IFN and the NLRP3 inflammasome in SLE.

BC-1215 inhibits ATP-induced IL-1β secretion via the FBXL2-mediated ubiquitination and degradation of not only NLRP3, but also pro-IL-1β in LPS-primed THP-1 cells

BC-1215, bis-pyridinyl benzyl ethanediamine, is an inhibitor of F-box only protein 3 (FBXO3) and exerts anti-inflammatory effects. BC-1215 inhibits interactions between FBXO3-F-box and the leucine rich repeat protein 2 (FBXL2), leading to the upregulation of FBXL2 expression, FBXL2-mediated ubiquitination and the degradation of tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) or NOD-, LRR- and the pyrin domain-containing protein 3 (NLRP3), which subsequently results in the down-regulation of inflammatory cytokine production. In the current study, we investigated the issue of whether or how BC-1215 suppresses the ATP-induced secretion of IL-1β in LPS-primed human macrophage-like cells, THP-1 cells. Our result show that pre-treatment with BC-1215 attenuated the ATP-induced secretion of IL-1β in LPS-primed THP-1 cells. Treatment of the LPS-primed THP-1 cells with BC-1215 resulted in a decrease in the level of NLRP3 and pro-IL-1β at the protein level, but not at the mRNA level. In addition, treatment with MG-132, but not leupeptin, inhibited the BC-1215-induced degradation of NLRP3 and pro-IL-1β proteins, and restored their levels, suggesting that BC-1215 decreases the stability of NLRP3 and pro-IL-1β at the protein level via proteasome-dependent degradation. Our results also show that FBXL2, which is increased by BC-1215, bound to and ubiquitinated NLRP3 and pro-IL-1β, but not pro-caspase-1. These collective results indicate that treatment with BC-1215, an inhibitor of FBXO3, inhibits ATP-induced IL-1β secretion via the FBXL2-mediated ubiquitination and degradation of pro-IL-1β as well as NLRP3 in LPS-primed THP-1 cells, suggesting that FBXO3 is a potential therapeutic target for developing agents against inflammatory diseases.

NLRP3 Inflammasome-Mediated Neuroinflammation and Related Mitochondrial Impairment in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder caused by the loss of dopamine neurons in the substantia nigra and the formation of Lewy bodies, which are mainly composed of alpha-synuclein fibrils. Alpha-synuclein plays a vital role in the neuroinflammation mediated by the nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in PD. A better understanding of the NLRP3 inflammasome-mediated neuroinflammation and the related mitochondrial impairment during PD progression may facilitate the development of promising therapies for PD. This review focuses on the molecular mechanisms underlying NLRP3 inflammasome activation, comprising priming and protein complex assembly, as well as the role of mitochondrial impairment and its subsequent inflammatory effects on the progression of neurodegeneration in PD. In addition, the therapeutic strategies targeting the NLRP3 inflammasome for PD treatment are discussed, including the inhibitors of NLRP3 inflammatory pathways, mitochondria-focused treatments, microRNAs, and other therapeutic compounds.

Oligomeric states of ASC specks regulate inflammatory responses by inflammasome in the extracellular space

Inflammasomes are multi-protein complexes and play a crucial role in host defense against pathogens. Downstream inflammatory responses through inflammasomes are known to be related to the oligomerization degree of ASC specks, but the detailed mechanism still remains unexplored. Here, we demonstrate that oligomerization degrees of ASC specks regulate the caspase-1 activation in the extracellular space. A protein binder specific for a pyrin domain (PYD) of ASC (ASCPYD) was developed, and structural analysis revealed that the protein binder effectively inhibits the interaction between PYDs, disassembling ASC specks into low oligomeric states. ASC specks with a low oligomerization degree were shown to enhance the activation of caspase-1 by recruiting and processing more premature caspase-1 through interactions between CARD of caspase-1 (caspase-1CARD) and CARD of ASC (ASCCARD). These findings can provide insight into controlling the inflammasome-mediated inflammatory process as well as the development of inflammasome-targeting drugs.

Blocking the Hormone Receptors Modulates NLRP3 in LPS-Primed Breast Cancer Cells

NOD-like receptor protein 3 (NLRP3) may contribute to the growth and propagation of breast cancer (BC). The effect of estrogen receptor-α (ER-α), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) on NLRP3 activation in BC remains unknown. Additionally, our knowledge of the effect of blocking these receptors on NLRP3 expression is limited. We used GEPIA, UALCAN, and the Human Protein Atlas for transcriptomic profiling of NLRP3 in BC. Lipopolysaccharide (LPS) and adenosine 5'-triphosphate (ATP) were used to activate NLRP3 in luminal A MCF-7 and in TNBC MDA-MB-231 and HCC1806 cells. Tamoxifen (Tx), mifepristone (mife), and trastuzumab (Tmab) were used to block ER-α, PR, and HER2, respectively, on inflammasome activation in LPS-primed MCF7 cells. The transcript level of NLRP3 was correlated with ER-ɑ encoding gene ESR1 in luminal A (ER-α⁺, PR⁺) and TNBC tumors. NLRP3 protein expression was higher in untreated and LPS/ATP-treated MDA-MB-231 cells than in MCF7 cells. LPS/ATP-mediated NLRP3 activation reduced cell proliferation and recovery of wound healing in both BC cell lines. LPS/ATP treatment prevented spheroid formation in MDA-MB-231 cells but did not affect MCF7. HGF, IL-3, IL-8, M-CSF, MCP-1, and SCGF-b cytokines were secreted in both MDA-MB-231 and MCF7 cells in response to LPS/ATP treatment. Tx (ER-α inhibition) promoted NLRP3 activation and increased migration and sphere formation after LPS treatment of MCF7 cells. Tx-mediated activation of NLRP3 was associated with increased secretion of IL-8 and SCGF-b compared to LPS-only-treated MCF7 cells. In contrast, Tmab (Her2 inhibition) had a limited effect on NLRP3 activation in LPS-treated MCF7 cells. Mife (PR inhibition) opposed NLRP3 activation in LPS-primed MCF7 cells. We have found that Tx increased the expression of NLRP3 in LPS-primed MCF7. These data suggest a link between blocking ER-α and activation of NLRP3, which was associated with increased aggressiveness of the ER-α⁺ BC cells.

The capsaicinoid nonivamide suppresses the inflammatory response and attenuates the progression of steatosis in a NAFLD-rat model

Nonalcoholic fatty liver disease (NAFLD) is relatively associated with comorbidities in obesity and metabolic inflammation. Low-grade inflammation following the high-fat diet (HFD)-induced NAFLD can promote the development of nonalcoholic steatohepatitis (NASH) through particularly liver-resident immune cell recruitment and hepatic nuclear factor kappa B (NF-κB) pathway. Therefore, inflammatory intervention may contribute to NASH reduction. Pelargonic acid vanillylamide (PAVA) or nonivamide is one of the pungent capsaicinoids of Capsicum species and has been found in chili peppers. Our previous study demonstrated that PAVA improved hepatic function, decreased oxidative stress and reduced apoptotic cell death but the insight role of PAVA on NAFLD is still unclear. Thus, this study aimed to investigate the underlying anti-inflammatory mechanism of PAVA in an NAFLD-rat model. Male Sprague Dawley rats were fed with normal diet or HFD for 16 weeks. Then high-fat rats were given vehicle or PAVA (1 mg/kg/day) for another 4 weeks. We found that PAVA alleviated hepatic inflammation associated with the reducing toll-like receptor 4/NF-κB pathway, showing significantly lower recruitment of cluster of differentiation 44. PAVA also maintained activity of insulin signaling pathway, and attenuated NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome formation. NAFLD progresses to NASH through transforming growth factor (TGF-β1), and also recovery to simple stage followed by PAVA suppresses pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, interleukin-6, and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway. Therefore, our findings suggest that PAVA provides a novel therapeutic approach for NAFLD and slows the progression to NASH.

Lacrimal Gland Epithelial Cells Shape Immune Responses through the Modulation of Inflammasomes and Lipid Metabolism

Lacrimal gland inflammation triggers dry eye disease through impaired tear secretion by the epithelium. As aberrant inflammasome activation occurs in autoimmune disorders including Sjögren's syndrome, we analyzed the inflammasome pathway during acute and chronic inflammation and investigated its potential regulators. Bacterial infection was mimicked by the intraglandular injection of lipopolysaccharide (LPS) and nigericin, known to activate the NLRP3 inflammasome. Acute injury of the lacrimal gland was induced by interleukin (IL)-1α injection. Chronic inflammation was studied using two Sjögren's syndrome models: diseased NOD.H2^b compared to healthy BALBc mice and Thrombospondin-1-null (TSP-1^-/-) compared to TSP-1^WTC57BL/6J mice. Inflammasome activation was investigated by immunostaining using the R26^ASC-citrine reporter mouse, by Western blotting, and by RNAseq. LPS/Nigericin, IL-1α and chronic inflammation induced inflammasomes in lacrimal gland epithelial cells. Acute and chronic inflammation of the lacrimal gland upregulated multiple inflammasome sensors, caspases 1/4, and interleukins Il1b and Il18. We also found increased IL-1β maturation in Sjögren's syndrome models compared with healthy control lacrimal glands. Using RNA-seq data of regenerating lacrimal glands, we found that lipogenic genes were upregulated during the resolution of inflammation following acute injury. In chronically inflamed NOD.H2^b lacrimal glands, an altered lipid metabolism was associated with disease progression: genes for cholesterol metabolism were upregulated, while genes involved in mitochondrial metabolism and fatty acid synthesis were downregulated, including peroxisome proliferator-activated receptor alpha (PPARα)/sterol regulatory element-binding 1 (SREBP-1)-dependent signaling. We conclude that epithelial cells can promote immune responses by forming inflammasomes, and that sustained inflammasome activation, together with an altered lipid metabolism, are key players of Sjögren's syndrome-like pathogenesis in the NOD.H2^b mouse lacrimal gland by promoting epithelial dysfunction and inflammation.

Combination of immune checkpoint inhibitors with radiation therapy in cancer: A hammer breaking the wall of resistance

Immuno-oncology is an emerging field in the treatment of oncological diseases, that is based on recruitment of the host immune system to attack the tumor. Radiation exposure may help to unlock the potential of the immune activating agents by enhancing the antigen release and presentation, attraction of immunocompetent cells to the inflammation site, and eliminating the tumor cells by phagocytosis, thereby leading to an overall enhancement of the immune response. Numerous preclinical studies in mouse models of glioma, murine melanoma, extracranial cancer, or colorectal cancer have contributed to determination of the optimal radiotherapy fractionation, as well as the radio- and immunotherapy sequencing strategies for maximizing the antitumor activity of the treatment regimen. At the same time, efficacy of combined radio- and immunotherapy has been actively investigated in clinical trials of metastatic melanoma, non-small-cell lung cancer and renal cell carcinoma. The present review summarizes the current advancements and challenges related to the aforementioned treatment approach.

Dimethyl Itaconate Attenuates CFA-Induced Inflammatory Pain via the NLRP3/ IL-1β Signaling Pathway

Itaconate plays a prominent role in anti-inflammatory effects and has gradually been ushered as a promising drug candidate for treating inflammatory diseases. However, its significance and underlying mechanism for inflammatory pain remain unexplored. In the current study, we investigated the effects and mechanisms of Dimethyl Itaconate (DI, a derivative of itaconate) on Complete Freund’s adjuvant (CFA)-induced inflammatory pain in a rodent model. Here, we demonstrated that DI significantly reduced mechanical allodynia and thermal hyperalgesia. The DI-attenuated neuroinflammation was evident with the amelioration of infiltrative macrophages in peripheral sites of the hind paw and the dorsal root ganglion. Concurrently, DI hindered the central microglia activation in the spinal cord. Mechanistically, DI inhibited the expression of pro-inflammatory factors interleukin (IL)-1β and tumor necrosis factor alpha (TNF-α) and upregulated anti-inflammatory factor IL-10. The analgesic mechanism of DI was related to the downregulation of the nod-like receptor protein 3 (NLRP3) inflammasome complex and IL-1β secretion. This study suggested possible novel evidence for prospective itaconate utilization in the management of inflammatory pain.

The two pore potassium channel THIK-1 regulates NLRP3 inflammasome activation

The NLRP3 (NLR family, pyrin domain containing 3) inflammasome is a multi-protein complex responsible for the activation of caspase-1 and the subsequent cleavage and activation of the potent proinflammatory cytokines IL-1β and IL-18, and pyroptotic cell death. NLRP3 is implicated as a driver of inflammation in a range of disorders including neurodegenerative diseases, type 2 diabetes, and atherosclerosis. A commonly reported mechanism contributing to NLRP3 inflammasome activation is potassium ion (K+ ) efflux across the plasma membrane. Identification of K+ channels involved in NLRP3 activation remains incomplete. Here, we investigated the role of the K+ channel THIK-1 in NLRP3 activation. Both pharmacological inhibitors and cells from THIK-1 knockout (KO) mice were used to assess THIK-1 contribution to macrophage NLRP3 activation in vitro. Pharmacological inhibition of THIK-1 inhibited caspase-1 activation and IL-1β release from mouse bone-marrow-derived macrophages (BMDMs), mixed glia, and microglia in response to NLRP3 agonists. Similarly, BMDMs and microglia from THIK-1 KO mice had reduced NLRP3-dependent IL-1β release in response to P2X7 receptor activation with ATP. Overall, these data suggest that THIK-1 is a regulator of NLRP3 inflammasome activation in response to ATP and identify THIK-1 as a potential therapeutic target for inflammatory disease.

IL-1α and IL-36 Family Cytokines Can Undergo Processing and Activation by Diverse Allergen-Associated Proteases

Inflammation driven by environmental allergens is an important source of morbidity in diseases such as asthma and eczema. How common allergens promote inflammation is still poorly understood, but previous studies have implicated the protease activity associated with many allergens as an important component of the pro-inflammatory properties of these agents. The IL-1 family cytokine, IL-33, has recently been shown to undergo processing and activation by proteases associated with multiple common allergens. However, it remains unclear whether the sensing of exogenous protease activity—as a proxy for the detection of invasive microbes, allergens and parasitic worms—is a general property of IL-1 family cytokines. In common with the majority of IL-1 family members, cytokines within the IL-36 sub-family (IL-36α, IL-36β and IL-36γ) are expressed as inactive precursors that require proteolysis within their N-termini for activation. Here we show that proteases associated with multiple common allergens of plant, insect, fungal and bacterial origin (including: Aspergillus fumigatus, ragweed, rye, house dust mite, cockroach and Bacillus licheniformis) are capable of processing and activating IL-36 family cytokines, with IL-36β being particularly susceptible to activation by multiple allergens. Furthermore, extracts from several allergens also processed and enhanced IL-1α activity. This suggests that multiple IL-1 family cytokines may serve as sentinels for exogenous proteases, coupling detection of such activity to unleashing the pro-inflammatory activity of these cytokines. Taken together with previous data on the diversity of proteases capable of activating IL-1 family cytokines, this suggests that members of this cytokine family may function as ‘activity recognition receptors’ for aberrant protease activity associated with infection, tissue injury or programmed necrosis.

IL-1 family cytokines serve as 'activity recognition receptors' for aberrant protease activity indicative of danger

Members of the extended IL-1 cytokine family play key roles as instigators of inflammation in numerous infectious and sterile injury contexts and are highly enriched at barrier surfaces such as the skin, lungs and intestinal mucosa. Because IL-1 family cytokines do not possess conventional ER-golgi trafficking and secretory signals, these cytokines are typically released into the extracellular space due to tissue damage resulting in necrosis, or pathogen detection resulting in pyroptosis. The latter feature, in combination with other factors, suggests that IL-1 family cytokines serve as canonical damage-associated molecular patterns (DAMPs), which instigate inflammation in response to tissue damage. However, IL-1 family cytokines also require a proteolytic activation step and diverse intracellular, extracellular and non-self proteases have been identified that are capable of processing and activating members of this family. This suggests that IL-1 family members function as sentinels for aberrant protease activity, which is frequently associated with infection or tissue damage. Here, we overview the diversity of proteases implicated in the activation of IL-1 family cytokines and suggest that this ancient cytokine family may have evolved to complement 'pattern recognition receptors', by serving as 'activity recognition receptors' enabling the detection of aberrant enzyme activity indicative of 'danger'.

Identifying Potential Gene Defect Patterns Related to COVID-19 Based on Pharmacological and Bioinformatics Analysis for Lung Adenocarcinoma

Background

Coronavirus disease 2019 (COVID-19) greatly affects cancer patients, especially those with lung cancer. This study aimed to identify potential drug targets for lung adenocarcinoma (LUAD) patients with COVID-19.

Methods

LUAD samples were obtained from public databases. Differentially expressed genes (DEGs) related to COVID-19 were screened. Protein–protein interactions among COVID-19-related genes, the traditional Chinese medicine (TCM) and TCM target genes were analyzed by CytoScape. The correlation between tumor microenvironment and COVID-19 target genes were assessed by Pearson correlation analysis. Unsupervised consensus clustering was conducted to categorize molecular subtypes.

Results

We filtered 26 COVID-19 target genes related to TCM for LUAD. Interleukin (IL)-17 signaling pathway and tumor necrosis factor (TNF) signaling pathway were significantly enriched in these 26 genes. A strong correlation was found between COVID-19 target genes and tumor microenvironment (TME), cell death. Importantly, interleukin-1beta (IL1B) was identified as a core gene in the protein–protein interactions (PPI) network. Based on the 26 target genes, two molecular subtypes showing distinct overall survival, TME and response to target therapy were developed.

Conclusions

This study explored 26 COVID-19 target genes, which could serve as potential therapeutic drug targets for LUAD. IL1B was verified as a critical target for developing new molecular drugs. Furthermore, two novel molecular subtypes showed the potential to guide personalized therapies in clinical practice.

Study of the immunologic response of marine-derived collagen and gelatin extracts for tissue engineering applications

The host immunologic response to a specific material is a critical aspect when considering it for clinical implementation. Collagen and gelatin extracted from marine sources have been proposed as biomaterials for tissue engineering applications, but there is a lack of information in the literature about their immunogenicity. In this work, we evaluated the immune response to collagen and/or gelatin from blue shark and codfish, previously extracted and characterized. After endotoxin evaluation, bone marrow-derived macrophages were exposed to the materials and a panel of pro- and anti-inflammatory cytokines were evaluated both for protein quantification and gene expression. Then, the impact of those materials in the host was evaluated through peritoneal injection in C57BL/6 mice. The results suggested shark collagen as the less immunogenic material, inducing low expression of pro-inflammatory cytokines as well as inducible nitric oxide synthase (encoded by Nos2) and high expression of Arginase 1 (encoded by Arg1). Although shark gelatin appeared to be the material with higher pro-inflammatory expression, it also presents a high expression of IL-10 (anti-inflammatory cytokine) and Arginase (both markers for M2-like macrophages). When injected in the peritoneal cavity of mice, our materials demonstrated a transient recruitment of neutrophil, being almost non-existent after 24 hours of injection. Based on these findings, the studied collagenous materials can be considered interesting biomaterial candidates for regenerative medicine as they may induce an activation of the M2-like macrophage population, which is involved in suppressing the inflammatory processes promoting tissue remodeling. STATEMENT OF SIGNIFICANCE: Marine-origin biomaterials are emerging in the biomedical arena, namely the ones based in marine-derived collagen/gelatin proposed as cell templates for tissue regeneration. Nevertheless, although the major cause of implant rejection in clinical practice is the host's negative immune response, there is a lack of information in the literature about the immunological impact of these marine collagenous materials. This work aims to contribute with knowledge about the immunologic response to collagen/gelatin extracted from blue shark and codfish skins. The results demonstrated that despite some differences observed, all the materials can induce a macrophage phenotype related with anti-inflammation resolution and then act as immuno-modulators and anti-inflammatory inducible materials.

C1q/tumour necrosis factor-related protein-9 aggravates lipopolysaccharide-induced inflammation via promoting NLRP3 inflammasome activation

The NLRP3 inflammasome plays a vital role in inflammation by increasing the maturation of interleukin-1β (IL-1β) and promoting pyroptosis. Given that C1q/tumour necrosis factor-related protein-9 (CTRP9) has been shown to be involved in diverse inflammatory diseases, we sought to assess the underlying impact of CTRP9 on NLRP3 inflammasome activation. In vitro, macrophages isolated from murine peritonea were stimulated with exogenous CTRP9, followed by lipopolysaccharide (LPS) and adenosine 5'-triphosphate (ATP). We demonstrated that CTRP9 markedly augmented the activation of the NLRP3 inflammasome, as shown by increased mature IL-1β secretion, triggering ASC speck formation and promoting pyroptosis. Mechanistically, CTRP9 increased the levels of NADPH oxidase 2 (NOX2)-derived reactive oxygen species (ROS). Suppressing ROS with N-acetylcysteine (NAC) or interfering with NOX2 by small interfering RNA weakened the promoting effect of CTRP9 on the NLRP3 inflammasome. Furthermore, NLRP3 inflammasome activation, pyroptosis and secretion of mature IL-1β were significantly decreased in macrophages from CTRP9-KO mice compared to those from WT mice with the same treatment. In vivo, we established a sepsis model by intraperitoneal injection of LPS into WT and CTRP9-KO mice. CTRP9 knockout improved the survival rates of the septic mice and attenuated NLRP3 inflammasome-mediated inflammation. In conclusion, our study indicates that CTRP9 aggravates LPS-induced inflammation by promoting NLRP3 inflammasome activation via the NOX2/ROS pathway. CTRP9 could be a promising target for NLRP3 inflammasome-driven inflammatory diseases.

Chloride Channel and Inflammation-Mediated Pathogenesis of Osteoarthritis

Articular cartilage allows the human body to buffer and absorb stress during normal exercise. It is mainly composed of cartilage cells and the extracellular matrix and is surrounded by the extracellular microenvironment formed by synovial fluid and various factors in it. Studies have shown that chondrocytes are the metabolic center of articular cartilage. Under physiological conditions, the extracellular matrix is in a dynamic balance of anabolism and catabolism, and various factors and physical and chemical conditions in the extracellular microenvironment are also in a steady state. This homeostasis depends on the normal function of proteins represented by various ion channels on chondrocytes. In mammalian chondrocyte species, ion channels are mainly divided into two categories: cation channels and anion channels. Anion channels such as chloride channels have become hot research topics in recent years. These channels play an extremely important role in various physiological processes. Recently, a growing body of evidence has shown that many pathological processes, abnormal concentration of mechanical stress and chloride channel dysfunction in articular cartilage lead to microenvironment disorders, matrix and bone metabolism imbalances, which cause partial aseptic inflammation. These pathological processes initiate extracellular matrix degradation, abnormal chondrocyte death, hyperplasia of inflammatory synovium and bony. Osteoarthritis (OA) is a common clinical disease in orthopedics. Its typical manifestations are joint inflammation and pain caused by articular cartilage degeneration, but its pathogenesis has not been fully elucidated. Focusing on the physiological functions and pathological changes of chloride channels and pathophysiology of aseptic inflammation furthers the understanding of OA pathogenesis and provides possible targets for subsequent medication development.

T cell apoptosis characterizes severe Covid-19 disease

Severe SARS-CoV-2 infections are characterized by lymphopenia, but the mechanisms involved are still elusive. Based on our knowledge of HIV pathophysiology, we hypothesized that SARS-CoV-2 infection-mediated lymphopenia could also be related to T cell apoptosis. By comparing intensive care unit (ICU) and non-ICU COVID-19 patients with age-matched healthy donors, we found a strong positive correlation between plasma levels of soluble FasL (sFasL) and T cell surface expression of Fas/CD95 with the propensity of T cells to die and CD4 T cell counts. Plasma levels of sFasL and T cell death are correlated with CXCL10 which is part of the signature of 4 biomarkers of disease severity (ROC, 0.98). We also found that members of the Bcl-2 family had modulated in the T cells of COVID-19 patients. More importantly, we demonstrated that the pan-caspase inhibitor, Q-VD, prevents T cell death by apoptosis and enhances Th1 transcripts. Altogether, our results are compatible with a model in which T-cell apoptosis accounts for T lymphopenia in individuals with severe COVID-19. Therefore, a strategy aimed at blocking caspase activation could be beneficial for preventing immunodeficiency in COVID-19 patients.

ALDOA maintains NLRP3 inflammasome activation by controlling AMPK activation

ABBREVIATIONS

ALDOA: aldolase A; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATG5: autophagy related 5; ATP: adenosine triphosphate; BMDMs: bone marrow-derived macrophages; CALCOCO2: calcium binding and coiled-coil domain 2; CASP1: caspase 1; CQ: chloroquine; FOXO3: forkhead box O3; IL1B: interleukin 1 beta; LPS: lipopolysaccharide; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MT: mutant; mtDNA: mitochondrial DNA; MTORC1: mechanistic target of rapamycin kinase complex 1; mtROS: mitochondrial reactive oxygen species; NLRP3: NLR family, pyrin domain containing 3; OPTN: optineurin; PBS: phosphate-buffered saline; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; SN: supernatant; SQSTM1/p62: sequestosome 1; STK11/LKB1: serine/threonine kinase 11; TOMM20: translocase of outer mitochondrial membrane 20; ULK1: unc-51 like autophagy activating kinase 1; v-ATPase: vacuolar type H+-ATPase; WT: wild-type.

Genetic targeting of Card19 is linked to disrupted NINJ1 expression, impaired cell lysis, and increased susceptibility to Yersinia infection

Cell death plays a critical role in inflammatory responses. During pyroptosis, inflammatory caspases cleave Gasdermin D (GSDMD) to release an N-terminal fragment that generates plasma membrane pores that mediate cell lysis and IL-1 cytokine release. Terminal cell lysis and IL-1β release following caspase activation can be uncoupled in certain cell types or in response to particular stimuli, a state termed hyperactivation. However, the factors and mechanisms that regulate terminal cell lysis downstream of GSDMD cleavage remain poorly understood. In the course of studies to define regulation of pyroptosis during Yersinia infection, we identified a line of Card19-deficient mice (Card19lxcn) whose macrophages were protected from cell lysis and showed reduced apoptosis and pyroptosis, yet had wild-type levels of caspase activation, IL-1 secretion, and GSDMD cleavage. Unexpectedly, CARD19, a mitochondrial CARD-containing protein, was not directly responsible for this, as an independently-generated CRISPR/Cas9 Card19 knockout mouse line (Card19Null) showed no defect in macrophage cell lysis. Notably, Card19 is located on chromosome 13, immediately adjacent to Ninj1, which was recently found to regulate cell lysis downstream of GSDMD activation. RNA-seq and western blotting revealed that Card19lxcn BMDMs have significantly reduced NINJ1 expression, and reconstitution of Ninj1 in Card19lxcn immortalized BMDMs restored their ability to undergo cell lysis in response to caspase-dependent cell death stimuli. Card19lxcn mice exhibited increased susceptibility to Yersinia infection, whereas independently-generated Card19Null mice did not, demonstrating that cell lysis itself plays a key role in protection against bacterial infection, and that the increased infection susceptibility of Card19lxcn mice is attributable to loss of NINJ1. Our findings identify genetic targeting of Card19 being responsible for off-target effects on the adjacent gene Ninj1, disrupting the ability of macrophages to undergo plasma membrane rupture downstream of gasdermin cleavage and impacting host survival and bacterial control during Yersinia infection.

Selenomethionine alleviates LPS-induced JNK/NLRP3 inflammasome-dependent necroptosis by modulating miR-15a and oxidative stress in chicken lungs

Selenium (Se) was involved in many physiological processes in humans and animals. microRNAs (miRNAs) also played important roles in lung diseases. However, the regulatory mechanism of miRNA in chicken lungs and the mechanism of lipopolysaccharide (LPS)-induced pneumonia remained unclear. To further study these mechanisms, we established a supplement of selenomethionine (SeMet) and/or LPS-treated chicken model and a cell model of LPS and/or high and low expression of miR-15a in chicken hepatocellular carcinoma (LMH) cells. We detected the expression of some selenoproteins, p-c-Jun N-terminal kinase (JNK), nod-like receptor protein 3 (NLRP3), caspase1, receptor-interacting serine-threonine kinase 1 (RIPK1), receptor-interacting serine-threonine kinase 3 (RIPK3), mixed lineage kinase domain-like pseudokinase (MLKL), miR-15a and oxidative stress kits. Additionally, we observed the morphology of lungs by H.E. staining in vitro. The results indicated that necroptosis occurred in LPS-treated chicken and LMH cells. Moreover, LPS stimulation inhibited miR-15a, and increased the expression of JNK, NLRP3, caspase1, RIPK1, RIPK3, MLKL. We also found that LPS treatment not only increased the content of H2O2 and MDA in the lungs but also increased the activities of iNOS and CAT and the content of GSH decreased. Conclusion: SeMet could reduce the oxidative damage and activate NLRP3 inflammasome reaction by stimulating miR-15a/JNK, thus reduced the pulmonary necroptosis induced by LPS.

Nicardipine Inhibits Priming of the NLRP3 Inflammasome via Suppressing LPS-Induced TLR4 Expression

The Nod-like receptor protein 3 (NLRP3) inflammasome is a multi-protein complex composed of NLRP3, pro-caspase-1, and apoptosis-associated speck-like protein that contains a caspase recruitment domain (ASC). After NLRP3 priming by lipopolysaccharide (LPS), the ligand of toll-like receptor 4 (TLR4), activation of the NLRP3 inflammasome triggers caspase-1 maturation, leading to pyroptosis and release of interleukin-1beta (IL-1beta). Expression of TLR4 modulates LPS-triggered inflammatory cascades as well as the NLRP3 signaling. L-type calcium channel antagonists are widely used as anti-hypertensive drugs and also exert anti-inflammatory effects through inhibiting release of cytokines including IL-1beta. However, few studies reveal effects of L-type calcium channel antagonists on the NLRP3 inflammasome. In this study, we investigated the effects of nicardipine and verapamil, both L-type calcium channel antagonists, on the NLRP3 inflammasome using differentiated THP-1 cells. Pyroptosis or levels of IL-1beta and caspase-1 were assayed by flow cytometry or enzyme-linked immunosorbent assay, respectively. ASC oligomerization was assayed by immunofluorescence microscopy. Expression of NLRP3 or TLR4 was assayed by polymerase chain reaction and immunoblotting. Nuclear factor-kappaB (NF-kappaB) pathway was also studied. Our results showed that pyroptosis and IL-1beta release were attenuated by nicardipine, but not verapamil. Nicardipine also mitigated caspase-1 activation, inhibited ASC oligomerization, and reduced NLRP3 expression. Furthermore, nicardipine downregulated phosphorylation or nuclear translocation of NF-kappaB p65, consistent with the inhibitory effect of nicardipine on LPS-induced TLR4 expression. In conclusion, nicardipine exerted anti-inflammatory effects through inhibiting NLRP3 inflammasome pathway. Nicardipine may mitigate NLRP3 priming via inhibiting NF-kappaB activation, mediated by suppressing LPS-induced TLR4 expression.

Decoding Cell Death: From a Veritable Library of Babel to Vade Mecum?

Programmed cell death (PCD) is a requisite feature of development and homeostasis but can also be indicative of infections, injuries, and pathologies. In concordance with these heterogeneous contexts, an array of disparate effector responses occur downstream of cell death and its clearance-spanning tissue morphogenesis, homeostatic turnover, host defense, active dampening of inflammation, and tissue repair. This raises a fundamental question of how a single contextually appropriate response ensues after an event of PCD. To explore how complex inputs may together tailor the specificity of the resulting effector response, here we consider (a) the varying contexts during which different cell death modalities are observed, (b) the nature of the information that can be passed on by cell corpses, and (c) the ways by which efferocyte populations synthesize signals from dying cells with those from the surrounding microenvironment.

The Antisocial Network: Cross Talk Between Cell Death Programs in Host Defense

Nearly all animal cells contain proteins evolved to trigger the destruction of the cell in which they reside. The activation of these proteins occurs via sequential programs, and much effort has been expended in delineating the molecular mechanisms underlying the resulting processes of programmed cell death (PCD). These efforts have led to the definition of apoptosis as a form of nonimmunogenic PCD that is required for normal development and tissue homeostasis, and of pyroptosis and necroptosis as forms of PCD initiated by pathogen infection that are associated with inflammation and immune activation. While this paradigm has served the field well, numerous recent studies have highlighted cross talk between these programs, challenging the idea that apoptosis, pyroptosis, and necroptosis are linear pathways with defined immunological outputs. Here, we discuss the emerging idea of cell death as a signaling network, considering connections between cell death pathways both as we observe them now and in their evolutionary origins. We also discuss the engagement and subversion of cell death pathways by pathogens, as well as the key immunological outcomes of these processes.

SARS-CoV-2, SARS-CoV-1, and HIV-1 derived ssRNA sequences activate the NLRP3 inflammasome in human macrophages through a non-classical pathway

Macrophages promote an early host response to infection by releasing pro-inflammatory cytokines such as interleukin-1β (IL-1β), TNF, and IL-6. The bioactivity of IL-1β is classically dependent on NLRP3 inflammasome activation, which culminates in caspase-1 activation and pyroptosis. Recent studies suggest a role for NLRP3 inflammasome activation in lung inflammation and fibrosis in both COVID-19 and SARS, and there is evidence of NLRP3 involvement in HIV-1 disease. Here, we show that GU-rich single-stranded RNA (GU-rich RNA) derived from SARS-CoV-2, SARS-CoV-1, and HIV-1 trigger a TLR8-dependent pro-inflammatory cytokine response from human macrophages in the absence of pyroptosis, with GU-rich RNA from the SARS-CoV-2 spike protein triggering the greatest inflammatory response. Using genetic and pharmacological inhibition, we show that the induction of mature IL-1β is through a non-classical pathway dependent on caspase-1, caspase-8, the NLRP3 inflammasome, potassium efflux, and autophagy while being independent of TRIF (TICAM1), vitamin D3, and pyroptosis.