Gasdermin-E Mediated Pyroptosis—A Novel Mechanism Regulating Migration, Invasion and Release of Inflammatory Cytokines in Rheumatoid Arthritis Fibroblast-like Synoviocytes

Flexible microneedles incorporating gold nanorods and tacrolimus for effective synergistic photothermal-chemotherapy of rheumatoid arthritis

Transdermal drug delivery systems for rheumatoid arthritis (RA) have garnered substantial attention due to their great potential to overcome limitations observed in conventional oral or injection strategies, including limited selectivity and adverse effects on extra-articular tissues. Microneedles (MNs) appear to be highly desirable carriers for transdermal drug delivery of RA. However, microneedles typically are unable to keep up with the flexibility of joints, which decreases the effectiveness of administration. In this study, we developed a flexible microneedles (FMNs) delivery system. And gelatin was employed for the fabrication of flexible backings for microneedles owing to its excellent ductility and biocompatibility. We achieved synergisticphotothermal-chemotherapy of RA by incorporating the chemical drug Tacrolimus (TAC) and the photothermal agent gold nanorods (AuNRs) into dissolving microneedles. Results showed a high mechanical strength of the proposed FMNs. In the animal model of adjuvant-induced arthritis (AA), it is indicated that the prepared FMNs inhibited the expression of related inflammatory cytokines such as IL-1ß and TNF-α while enhancing bone repair and other related factors. Thus, the combination therapy of FMNs-mediated hyperthermia and chemotherapy can serve as a novel and synergistic treatment option for RA.

Pyroptosis in Skeleton Diseases: A Potential Therapeutic Target Based on Inflammatory Cell Death

Skeletal disorders, including fractures, osteoporosis, osteoarthritis, rheumatoid arthritis, and spinal degenerative conditions, along with associated spinal cord injuries, significantly impair daily life and impose a substantial burden. Many of these conditions are notably linked to inflammation, with some classified as inflammatory diseases. Pyroptosis, a newly recognized form of inflammatory cell death, is primarily triggered by inflammasomes and executed by caspases, leading to inflammation and cell death through gasdermin proteins. Emerging research underscores the pivotal role of pyroptosis in skeletal disorders. This review explores the pyroptosis signaling pathways and their involvement in skeletal diseases, the modulation of pyroptosis by other signals in these conditions, and the current evidence supporting the therapeutic potential of targeting pyroptosis in treating skeletal disorders, aiming to offer novel insights for their management.

Circular RNA hsa_circ_0000175 Serves as a Potential Biomarker for Rheumatoid Arthritis via miR-31-5p/GSDME Axis

Rheumatoid arthritis (RA) is a common inflammatory autoimmune disease characterized by synovial inflammation and joint damage. Previous studies have shown that pyroptosis plays an important role in the pathogenesis of RA. In this study, the effects of circular RNA hsa_circ0000175 on pyroptosis and inflammation of RA were evaluated. Serum levels of circ_0000175 and miR-31-5p were determined by RT-qPCR, and the correlation between them was evaluated by Spearman correlation analysis. Fibroblast-like synoviocytes (FLSs) were extracted and prepared for in vitro study. The subcellular localization of circ_0000175 was detected by FISH assay. Pyroptosis and inflammatory cytokines interleukin (IL)-1β, IL-18 and IL-6 were measured by flow cytometry and ELISA, respectively. RNA pull-down and luciferase reporter assays verified the interaction between circ_0000175 and miR-31-5p. Western blot was used to detect the differential expression of pyroptosis-related factors (GSDME-N, GSDMD-N, cleaved caspase-1 and cleaved caspase-3). Circ_0000175 level was increased but miR-31-5p expression was decreased in PBMCs of RA patients and LPS/ATP-treated FLSs, companied with negative correlation. Moreover, miR-31-5p was a target of circ_0000175 in RA-FLSs. Silencing of circ_0000175 or overexpression of miR-31-5p significantly alleviated LPS/ATP-induced pyroptosis in FLSs through both caspase-1/GSDMD and caspase-3/GSDME pathways. Additionally, GSDME was identified as the target of miR-31-5p. The inhibitory effects of circ_0000175 depletion on pyroptosis and inflammation in RA-FLSs treated with LPS/ATP were strengthened by GSDME knockdown. Circ_0000175 can induce pyroptosis and trigger inflammatory response during the occurrence of RA through the miR-31-5p/GSDME axis, which provides a novel therapeutic target for RA treatment.

Neutrophil Extracellular Traps Induce Pyroptosis of Rheumatoid Arthritis Fibroblast-Like Synoviocytes via the NF-κB/Caspase 3/GSDME Pathway

Rheumatoid arthritis (RA) is an enduring, progressive autoimmune disorder. Abnormal activation of fibroblast-like synoviocytes (FLSs) has been proposed as the initiating factor for inflammation of the synovium and bone destruction. Neutrophil extracellular traps (NETs), which are web-like structures composed of DNA, histones, and granule proteins, are involved in the development of RA in multiple aspects. Pyroptosis, gasdermin-mediated inflammatory programmed cell death, plays a vital function in the etiopathogenesis of RA. However, the exact mechanism underlying NETs-induced pyroptosis in FLSs of RA and its impact on cellular pathogenic behavior remain undefined. In this study, we demonstrated that gasdermin E (GSDME) expression was upregulated in RA plasma and synoviums, which was positively correlated with the elevated cell-free DNA (cfDNA) and citrullinated histone 3 (Cit H3) levels in the plasma. Additionally, in vitro experiments have shown that NETs triggered caspase 3/GSDME-mediated pyroptosis in RA-FLSs, characterized by decreased cell viability, cell membrane blebbing, and rupture, as well as increased levels of pyroptosis-related proteins and pro-inflammatory cytokines. Again, silencing GSDME significantly inhibited pyroptosis and suppressed the migration, invasion, and secretion of pro-inflammatory cytokines in RA-FLSs. Furthermore, we also found that the nuclear factor-kappa B (NF-κB) pathway, serving as an upstream mechanism, was involved in FLS pyroptosis. In conclusion, our investigation indicated that NETs could induce RA-FLS pyroptosis and facilitate phenotypic transformation through targeting the NF-κB/caspase 3/GSDME axis. This is the first to explore the crucial role of NETs-induced FLS pyroptosis in the progression of RA, providing novel targets for the clinical management of refractory RA.

New Potentiality of Bioactive Substances: Regulating the NLRP3 Inflammasome in Autoimmune Diseases

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an essential component of the human innate immune system, and is closely associated with adaptive immunity. In most cases, the activation of the NLRP3 inflammasome requires priming and activating, which are influenced by various ion flux signals and regulated by various enzymes. Aberrant functions of intracellular NLRP3 inflammasomes promote the occurrence and development of autoimmune diseases, with the majority of studies currently focused on rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. In recent years, a number of bioactive substances have shown new potentiality for regulating the NLRP3 inflammasome in autoimmune diseases. This review provides a concise overview of the composition, functions, and regulation of the NLRP3 inflammasome. Additionally, we focus on the newly discovered bioactive substances for regulating the NLRP3 inflammasome in autoimmune diseases in the past three years.

Curcumin Co-Encapsulation Potentiates Anti-Arthritic Efficacy of Meloxicam Biodegradable Nanoparticles in Adjuvant-Induced Arthritis Animal Model

This study aimed to evaluate the anti-arthritic activity of curcumin and meloxicam co-loaded PLGA nanoparticles in adjuvant-induced arthritic rats. PLGA nanoparticles encapsulating curcumin (nCur) and meloxicam (nMlx) alone and in combination (nCur/Mlx) were used to characterize zeta size and potential, polydispersity index, encapsulation efficiency (%), compound-polymer interactions (FT-IR analysis), and surface morphology (SEM imaging). In vivo, Complete Freund's adjuvant-induced arthritic rats were intraperitoneally (i.p.) administered with curcumin, meloxicam, curcumin plus meloxicam, nCur, nMlx, and nCur/Mlx for 28 consecutive days. Results showed that nCur, nMlx, and nCur/Mlx significantly (p ≤ 0.05) reduced paw swelling and arthritic score, restored body weight and the immune organ index (thymus and spleen), as well as attenuated serum inflammatory markers (RF, CRP, and PGE2) and oxidative stress parameters (MDA, SOD, and CAT) in adjuvant-induced arthritic rats compared to free compounds. In addition, mono- and dual-compound-loaded nanoparticles significantly (p ≤ 0.05) down-regulated pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), up-regulated anti-inflammatory cytokines (IL-4, IL-10, and IFN-γ), and modulated OPG and RANKL expressions in paw tissue. The aforementioned results were further confirmed through radiological and histopathological examinations. Furthermore, the anti-arthritic effect of nCur/Mlx was notably (p ≤ 0.05) enhanced compared to nCur or nMlx alone. In conclusion, the co-nanoencapsulation of curcumin could potentiate the anti-arthritic activity of meloxicam and could provide a novel therapeutic approach for the formulation of nanocarrier pharmaceutical products for the management of arthritis.

Can pyroptosis be a new target in rheumatoid arthritis treatment?

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease of undefined etiology, with persistent synovial inflammation and destruction of articular cartilage and bone. Current clinical drugs for RA mainly include non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, disease modifying anti-rheumatic drugs (DMARDs) and so on, which can relieve patients' joint symptoms. If we want to have a complete cure for RA, there are still some limitations of these drugs. Therefore, we need to explore new mechanisms of RA to prevent and treat RA radically. Pyroptosis is a newly discovered programmed cell death (PCD) in recent years, which is characterized by the appearance of holes in cell membranes, cell swelling and rupture, and the release of intracellular pro-inflammatory factors into the extracellular space, resulting in a strong inflammatory response. The nature of pyroptosis is pro-inflammatory, and whether it is participating in the development of RA has attracted a wide interest among scholars. This review describes the discovery and mechanism of pyroptosis, the main therapeutic strategies for RA, and the role of pyroptosis in the mechanism of RA development. From the perspective of pyroptosis, the study of new mechanisms of RA may provide a potential target for the treatment of RA and the development of new drugs in the clinics.

The roles of chemokines following intracerebral hemorrhage in animal models and humans

Intracerebral hemorrhage (ICH) is one common yet devastating stroke subtype, imposing considerable burdens on families and society. Current guidelines are limited to symptomatic treatments after ICH, and the death rate remains significant in the acute stage. Thus, it is crucial to promote research to develop new targets on brain injury after ICH. In response to hematoma formation, amounts of chemokines are released in the brain, triggering the infiltration of resident immune cells in the brain and the chemotaxis of peripheral immune cells via the broken blood-brain barrier. During the past decades, mounting studies have focused on the roles of chemokines and their receptors in ICH injury. This review summarizes the latest advances in the study of chemokine functions in the ICH. First, we provide an overview of ICH epidemiology and underlying injury mechanisms in the pathogenesis of ICH. Second, we introduce the biology of chemokines and their receptors in brief. Third, we outline the roles of chemokines in ICH according to subgroups, including CCL2, CCL3, CCL5, CCL12, CCL17, CXCL8, CXCL12, and CX3CL1. Finally, we summarize current drug usage targeting chemokines in ICH and other cardio-cerebrovascular diseases. This review discusses the expressions of these chemokines and receptors under normal or hemorrhagic conditions and cell-specific sources. Above all, we highlight the related data of these chemokines in the progression and outcomes of the ICH disease in preclinical and clinical studies and point to therapeutic opportunities targeting chemokines productions and interactions in treating ICH, such as accelerating hematoma absorption and alleviating brain edema.

Targeting inflammasome-dependent mechanisms as an emerging pharmacological approach for osteoarthritis therapy

Arthritic diseases have attracted enormous scientific interest because of increased worldwide prevalence and represent a significant socioeconomic burden. Osteoarthritis (OA) is the most prevalent form of arthritis. It is a disorder of the diarthrodial joints, characterized by degeneration and loss of articular cartilage associated with adjacent subchondral bone changes. Chronic and unresolving inflammation has been identified as a critical factor driving joint degeneration and pain in OA. Despite numerous attempts at therapeutic intervention, no effective disease-modifying agents targeting OA inflammation are available to the patients. Inflammasomes are protein complexes known to play a critical role in the inflammatory pathology of several diseases, and their roles in OA pathogenesis have become evident over the last decade. In this sense, it is relevant to evaluate the vital role of inflammasomes as potential modulators of pathogenic features in OA. This review will provide an overview and perspectives on why understanding inflammasome activation is critical for identifying effective OA therapies. We elaborate on the contribution of extracellular mediators from the circulatory system and synovial fluid as well as intracellular activators within the synovial fibroblasts and articular chondrocytes toward invoking the inflammasome in OA. We further discuss the merits of emerging inflammasome targeting therapies and speculate on the potential strategies for inflammasome blockade for OA therapy.

Pyroptosis in inflammatory bone diseases: Molecular insights and targeting strategies

Inflammatory bone diseases include osteoarthritis (OA) and rheumatoid arthritis (RA), which can cause severe bone damage in a chronic inflammation state, putting tremendous pressure on the patients' families and government agencies regarding medical costs. In addition, the complexity of osteoimmunology makes research on these diseases difficult. Hence, it is urgent to determine the potential mechanisms and find effective drugs to target inflammatory bone diseases to reduce the negative effects of these diseases. Recently, pyroptosis, a gasdermin-induced necrotic cell death featuring secretion of pro-inflammatory cytokines and lysis, has become widely known. Based on the effect of pyroptosis on immunity, this process has gradually emerged as a vital component in the etiopathogenesis of inflammatory bone diseases. Herein, we review the characteristics and mechanisms of pyroptosis and then focus on its clinical significance in inflammatory bone diseases. In addition, we summarize the current research progress of drugs targeting pyroptosis to enhance the therapeutic efficacy of inflammatory bone diseases and provide new insights for future directions.

How Pyroptosis Contributes to Inflammation and Fibroblast-Macrophage Cross-Talk in Rheumatoid Arthritis

About thirty years ago, a new form of pro-inflammatory lytic cell death was observed and termed pyroptosis. Only in 2015, gasdermins were defined as molecules that create pores at the plasma membrane and drive pyroptosis. Today, we know that gasdermin-mediated death is an important antimicrobial defence mechanism in bacteria, yeast and mammals as it destroys the intracellular niche for pathogen replication. However, excessive and uncontrolled cell death also contributes to immunopathology in several chronic inflammatory diseases, including arthritis. In this review, we discuss recent findings where pyroptosis contributes to tissue damage and inflammation with a main focus on injury-induced and autoimmune arthritis. We also review novel functions and regulatory mechanisms of the pyroptotic executors gasdermins. Finally, we discuss possible models of how pyroptosis may contribute to the cross-talk between fibroblast and macrophages, and also how this cross-talk may regulate inflammation by modulating inflammasome activation and pyroptosis induction.