Research progress on the clinical application and mechanism of iguratimod in the treatment of autoimmune diseases and rheumatic diseases

Systemic Lupus Erythematosus Exacerbates Hip Arthritis by Promoting Chondrocyte Pyroptosis in the Femoral Head via Activating the NF-κB Pathway

Systemic lupus erythematosus (SLE) is an autoimmune disease characterised by chronic inflammation and immune dysregulation, significantly impacting multiple organ systems, including the joints. While SLE is known to contribute to musculoskeletal complications, its role in hip arthritis development and the underlying mechanisms remain poorly understood. This study aims to investigate the relationship between SLE and hip arthritis progression using MRL/lpr mice, which exhibit early-onset SLE, compared with MRL/MpJ control mice at 14 weeks of age. Through comprehensive histological, immunohistochemical and molecular analyses, we evaluated articular cartilage (AC) degeneration, extracellular matrix (ECM) metabolism, inflammatory responses, and chondrocyte pyroptosis. Our results demonstrated that MRL/lpr mice developed an accelerated hip arthritis-like phenotype, manifesting as enhanced AC degeneration, impaired chondrocyte proliferation, heightened apoptosis and promoted inflammatory cytokine production. Notably, SLE markedly stimulated chondrocyte pyroptosis by increasing pyroptosis-related proteins, including NLRP3, ASC, CASPASE-1 and GSDMD, via activating the NF-κB pathway. These findings establish a novel mechanistic link between SLE and hip arthritis progression, demonstrating that SLE promotes chondrocyte pyroptosis to exacerbate AC degeneration via NF-κB activation, highlighting chondrocyte pyroptosis as a key driver of SLE-associated hip arthritis and a potential therapeutic target for mitigating SLE-induced joint manifestations.

Systemic Lupus Erythematosus Stimulates Chondrocyte Pyroptosis to Aggravate Arthritis via Suppression of NRF-2/KEAP-1 and NF-κB Pathway

Purpose

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by diverse clinical manifestations, including joint symptoms. Arthritis represents one of the earliest manifestations of SLE, profoundly affecting the quality of life for affected individuals, yet the underlying mechanisms of SLE-associated arthritis remain insufficiently investigated. The study aimed to investigate the impact of SLE exacerbation on arthritis using the MRL/lpr mouse model, which closely mimics human SLE manifestations.

Methods

In the present study, we evaluated the impact of SLE onset on knee joint degeneration by comparing arthritic phenotype and complex molecular alterations between 6 female 14-week-old MRL/lpr mice, which manifest SLE, and MRL/MpJ mice, which remain unaffected.

Results

Our results demonstrated that MRL/lpr mice exhibited a more severe arthritic phenotype compared to MRL/MpJ mice, characterized by elevated Osteoarthritis Research Society International (OARSI) scores (P < 0.01), disrupted extracellular matrix metabolism, impaired chondrocyte proliferation and increased apoptosis. Notably, inflammatory cytokines proteins such as IL-1β and TNF-α (both P < 0.01), IL-18 and IL-6 (both P < 0.05), were significantly increased in articular cartilage of MRL/lpr mice, accompanied by increased expression of calcitonin gene-related peptide (CGRP) (P < 0.05), NETRIN-1, and NESTIN (both P < 0.01), indicating that SLE promotes inflammation response and sensory nerve ingrowth in the knee joint, contributing to the progression of arthritis. Mechanistic analysis revealed that SLE exacerbation intensified chondrocyte pyroptosis by upregulating pyroptotic-related proteins, including NLRP3, CASPASE-1, and gasdermin D (all P < 0.01), through the regulation of the nuclear factor erythroid 2-related factor (NRF-2)/KEAP-1 and nuclear factor kappa-B (NF-κB) pathway.

Conclusion

Collectively, our findings underscore the mechanistic connection between chondrocyte pyroptosis and arthritis exacerbation in SLE, suggesting potential therapeutic targets for mitigating arthritis progression in the context of SLE.

Iguratimod improves bleomycin-induced pulmonary inflammation and fibrosis by regulating macrophage polarization through inhibiting the TLR4/NF-κB pathway

Introduction

Pulmonary fibrosis (PF) is a fatal pathological subtype of interstitial lung disease, frequently manifests as a pulmonary complication of connective tissue disease. Iguratimod (IGU) is a new class of anti-rheumatic drugs used in the treatment of rheumatoid arthritis (RA). Studies have reported that RA patients treated with IGU have better lung function, and IGU effectively ameliorates PF. However, the mechanism by which IGU improves PF is still unclear. This study aims to elucidate the therapeutic efficacy and mechanisms of IGU in PF through in vivo and in vitro investigations, so as to provide a new treatment method for PF.

Methods

In our research, bleomycin (BLM)-induced PF of mice were used to observe the therapeutic effect of different concentrations of IGU. And the effects of IGU on macrophage polarization and activation pathway TLR4/NF-κB in lung tissue were analyzed. In addition, Raw264.7 macrophages were induced to M1 and M2 polarization in vitro, and the effects of IGU on Raw264.7 macrophage polarization and related pathways were observed.

Results

In our study, database analysis suggested that macrophage polarization-relative genes and pathways as well as TLR4 activation played important roles in BLM-induced PF in mice. Besides, we found that IGU effectively ameliorated BLM-induced PF and epithelial-mesenchymal transition in mice, and inhibited the polarization of M1/M2 macrophages at different stages of PF. Moreover, In vitro studies further demonstrated that IGU suppressed M1 polarization of Raw264.7 and its activation pathway TLR4/NF-κB.

Discussion

In summary, IGU inhibits the activation of macrophages and M1 polarization through inhibiting the TLR4/NF-κB pathway, thereby improving BLM-induced pulmonary inflammation and fibrosis in mice. It is suggested that IGU may be a new therapeutic option for interstitial pulmonary fibrosis.

Advances in chimeric antigen receptor T cell therapy for autoimmune and autoinflammatory diseases and their complications

Chimeric antigen receptor T (CAR-T) cells are genetically engineered T cells expressing transmembrane chimeric antigen receptors with specific targeting abilities. As an emerging immunotherapy, the use of CAR-T cells has made significant breakthroughs in cancer treatment, particularly for hematological malignancies. The success of CAR-T cell therapy in blood cancers highlights its potential for other conditions in which the clearance of pathological cells is therapeutic, such as liver diseases, infectious diseases, heart failure, and diabetes. Given the limitations of current therapies for autoimmune diseases, researchers have actively explored the potential therapeutic value of CAR-T cells and their derivatives in the field of autoimmune diseases. This review focuses on the research progress and current challenges of CAR-T cells in autoimmune diseases with the aim of providing a theoretical basis for the precise treatment of autoimmune diseases. In the future, CAR-T cells may present new therapeutic modalities and ultimately provide hope for patients with autoimmune diseases.

The role of hypoxic microenvironment in autoimmune diseases

The hypoxic microenvironment, characterized by significantly reduced oxygen levels within tissues, has emerged as a critical factor in the pathogenesis and progression of various autoimmune diseases (AIDs). Central to this process is the hypoxia-inducible factor-1 (HIF-1), which orchestrates a wide array of cellular responses under low oxygen conditions. This review delves into the multifaceted roles of the hypoxic microenvironment in modulating immune cell function, particularly highlighting its impact on immune activation, metabolic reprogramming, and angiogenesis. Specific focus is given to the mechanisms by which hypoxia contributes to the development and exacerbation of diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), and dermatomyositis (DM). In these conditions, the hypoxic microenvironment not only disrupts immune tolerance but also enhances inflammatory responses and promotes tissue damage. The review also discusses emerging therapeutic strategies aimed at targeting the hypoxic pathways, including the application of HIF-1α inhibitors, mTOR inhibitors, and other modulators of the hypoxic response. By providing a comprehensive overview of the interplay between hypoxia and immune dysfunction in AIDs, this review offers new perspectives on the underlying mechanisms of these diseases and highlights potential avenues for therapeutic intervention.

Advances in the study of artemisinin and its derivatives for the treatment of rheumatic skeletal disorders, autoimmune inflammatory diseases, and autoimmune disorders: a comprehensive review

Artemisinin and its derivatives are widely recognized as first-line treatments for malaria worldwide. Recent studies have demonstrated that artemisinin-based antimalarial drugs, such as artesunate, dihydroartemisinin, and artemether, not only possess excellent antimalarial properties but also exhibit antitumor, antifungal, and immunomodulatory effects. Researchers globally have synthesized artemisinin derivatives like SM735, SM905, and SM934, which offer advantages such as low toxicity, high bioavailability, and potential immunosuppressive properties. These compounds induce immunosuppression by inhibiting the activation of pathogenic T cells, suppressing B cell activation and antibody production, and enhancing the differentiation of regulatory T cells. This review summarized the mechanisms by which artemisinin and its analogs modulate excessive inflammation and immune responses in rheumatic and skeletal diseases, autoimmune inflammatory diseases, and autoimmune disorders, through pathways including TNF, Toll-like receptors, IL-6, RANKL, MAPK, PI3K/AKT/mTOR, JAK/STAT, and NRF2/GPX4. Notably, in the context of the NF-κB pathway, artemisinin not only inhibits NF-κB expression by disrupting upstream cascades and/or directly binding to NF-κB but also downregulates multiple downstream genes controlled by NF-κB, including inflammatory chemokines and their receptors. These downstream targets regulate various immune cell functions, apoptosis, proliferation, signal transduction, and antioxidant responses, ultimately intervening in systemic autoimmune diseases and autoimmune responses in organs such as the kidneys, nervous system, skin, liver, and biliary system by modulating immune dysregulation and inflammatory responses. Ongoing multicenter randomized clinical trials are investigating the effects of these compounds on rheumatic, inflammatory, and autoimmune diseases, with the aim of translating promising preclinical data into clinical applications.

A systematic review and meta-analysis of the efficacy and safety of iguratimod in the treatment of inflammatory arthritis and degenerative arthritis

Objective

To assess the efficacy and safety of iguratimod (IGU) in the treatment of inflammatory arthritis and degenerative arthritis.

Methods

Initially, randomized controlled trials (RCTs) on using IGU in treating inflammatory arthritis and degenerative arthritis were systematically gathered from various databases up to February 2024. Subsequently, two researchers independently screened the literature, extracted data, assessed the risk of bias in included studies, and conducted a meta-analysis using RevMan 5.4 software.

Results

Fifty-four RCTs involving three inflammatory arthritis were included, including ankylosing spondylitis (AS), osteoarthritis (OA), and rheumatoid arthritis (RA). For AS, the meta-analysis results showed that IGU may decrease BASDAI (SMD -1.68 [-2.32, -1.03], P < 0.00001) and BASFI (WMD -1.29 [-1.47, -1.11], P < 0.00001); IGU may also decrease inflammatory factor [ESR: (WMD -10.33 [-14.96, -5.70], P < 0.0001); CRP: (WMD -10.11 [-14.55, -5.66], P < 0.00001); TNF-α: (WMD -6.22 [-7.97, -4.47], P < 0.00001)]. For OA, the meta-analysis results showed that IGU may decrease VAS (WMD -2.20 [-2.38, -2.01], P < 0.00001) and WOMAC (WMD -7.27 [-12.31, -2.24], P = 0.005); IGU may also decrease IL-6 (WMD -8.72 [-10.00, -7.45], P < 0.00001). For RA, the meta-analysis results showed that IGU may improve RA remission rate [ACR20: (RR 1.18 [1.02, 1.35], P = 0.02); ACR50: (RR 1.32 [1.05, 1.64], P = 0.02); ACR70: (RR 1.44 [1.02, 2.04], P = 0.04)] and decrease DAS28 (WMD -0.92 [-1.20, -0.63], P < 0.00001); IGU may also decrease inflammatory factors [CRP: (SMD -1.36 [-1.75, -0.96], P < 0.00001); ESR: (WMD -9.09 [-11.80, -6.38], P < 0.00001); RF: (SMD -1.21 [-1.69, -0.73], P < 0.00001)]. Regarding safety, adding IGU will not increase the incidence of adverse events.

Conclusion

IGU might emerge as a promising and secure therapeutic modality for addressing AS, OA, and RA.

Systematic Review Registration

Identifier PROSPERO: CRD42021289249.

Transdermal delivery of iguratimod and colchicine ethosome by dissolving microneedle patch for the treatment of recurrent gout

This study introduces a novel approach of repetitive modeling to simulate the pathological process of recurrent gout attacks in humans. This methodology addresses the instability issues present in rat models of gout, providing a more accurate representation of the damage recurrent gout episodes inflict on human skeletal systems. A soluble nanoneedle system encapsulating colchicine and iguratimod ethosomal formulations was developed. This system aims to modulate inflammatory cytokines and inhibit osteoclast activity, thereby treating inflammatory pain and bone damage associated with recurrent gout. Additionally, a comprehensive evaluation of the microneedles' appearance, morphology, mechanical properties, and penetration capability confirmed their effectiveness in penetrating the stratum corneum. Dissolution tests and skin irritation assessments demonstrated that these microneedles dissolve rapidly without irritating the skin. In vitro permeation studies indicated that transdermal drug delivery via these microneedles is more efficient and incurs lower drug loss compared to traditional topical applications. In vivo pharmacodynamic assessments conducted in animal models revealed significant analgesic and anti-inflammatory effects when both types of microneedles were used together. Further analyses, including X-ray imaging, hematoxylin and eosin (H&E) staining, Safranin-O/fast green staining, tartrate-resistant acid phosphatase staining, and quantification of osteoclasts, confirmed the bone-protective effects of the microneedle combination. In conclusion, the findings of this research underscore the potential of this novel therapeutic approach for clinical application in the treatment of recurrent gout.

Roles of the Caspase-11 Non-Canonical Inflammasome in Rheumatic Diseases

Inflammasomes are intracellular multiprotein complexes that activate inflammatory signaling pathways. Inflammasomes comprise two major classes: canonical inflammasomes, which were discovered first and are activated in response to a variety of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), and non-canonical inflammasomes, which were discovered recently and are only activated in response to intracellular lipopolysaccharide (LPS). Although a larger number of studies have successfully demonstrated that canonical inflammasomes, particularly the NLRP3 inflammasome, play roles in various rheumatic diseases, including rheumatoid arthritis (RA), infectious arthritis (IR), gouty arthritis (GA), osteoarthritis (OA), systemic lupus erythematosus (SLE), psoriatic arthritis (PA), ankylosing spondylitis (AS), and Sjögren's syndrome (SjS), the regulatory roles of non-canonical inflammasomes, such as mouse caspase-11 and human caspase-4 non-canonical inflammasomes, in these diseases are still largely unknown. Interestingly, an increasing number of studies have reported possible roles for non-canonical inflammasomes in the pathogenesis of various mouse models of rheumatic disease. This review comprehensively summarizes and discusses recent emerging studies demonstrating the regulatory roles of non-canonical inflammasomes, particularly focusing on the caspase-11 non-canonical inflammasome, in the pathogenesis and progression of various types of rheumatic diseases and provides new insights into strategies for developing potential therapeutics to prevent and treat rheumatic diseases as well as associated diseases by targeting non-canonical inflammasomes.