Anti-allodynic action of the disease-modifying anti-rheumatic drug iguratimod in a rat model of neuropathic pain

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

Autoimmune diseases are affected by complex pathophysiology involving multiple cell types, cytokines, antibodies and mimicking factors. Different drugs are used to improve these autoimmune responses, including nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, antibodies, and small molecule drugs (DMARDs), which are prevalent clinically in the treatment of rheumatoid arthritis (RA), etc. However, low cost-effectiveness, reduced efficacy, adverse effects, and patient non-response are unattractive factors driving the development of new drugs such as iguratimod. As a new disease-modifying antirheumatic drug, iguratimod has pharmacological activities such as regulating autoimmune disorders, inflammatory cytokines, regulating immune cell activation, differentiation and proliferation, improving bone metabolism, and inhibiting fibrosis. In recent years, clinical studies have found that iguratimod is effective in the treatment of RA, SLE, IGG4-RD, Sjogren 's syndrome, ankylosing spondylitis, interstitial lung disease, and other autoimmune diseases and rheumatic diseases. The amount of basic and clinical research on other autoimmune diseases is also increasing. Therefore, this review systematically reviews the latest relevant literature in recent years, reviews the research results in recent years, and summarizes the research progress of iguratimod in the treatment of related diseases. This review highlights the role of iguratimod in the protection of autoimmune and rheumatic bone and related immune diseases. It is believed that iguratimod's unique mode of action and its favorable patient response compared to other DMARDs make it a suitable antirheumatic and bone protective agent in the future.

Iguratimod Ameliorates the Severity of Secondary Progressive Multiple Sclerosis in Model Mice by Directly Inhibiting IL-6 Production and Th17 Cell Migration via Mitigation of Glial Inflammation

We previously reported a novel secondary progressive multiple sclerosis (SPMS) model, progressive experimental autoimmune encephalomyelitis (pEAE), in oligodendroglia-specific Cx47-inducible conditional knockout (Cx47 icKO) mice. Based on our prior study showing the efficacy of iguratimod (IGU), an antirheumatic drug, for acute EAE treatment, we aimed to elucidate the effect of IGU on the SPMS animal model. We induced pEAE by immunizing Cx47 icKO mice with myelin oligodendrocyte glycoprotein peptide 35-55. IGU was orally administered from 17 to 50 days post-immunization. We also prepared a primary mixed glial cell culture and measured cytokine levels in the culture supernatant after stimulation with designated cytokines (IL-1α, C1q, TNF-α) and lipopolysaccharide. A migration assay was performed to evaluate the effect of IGU on the migration ability of T cells toward mixed glial cell cultures. IGU treatment ameliorated the clinical signs of pEAE, decreased the demyelinated area, and attenuated glial inflammation on immunohistochemical analysis. Additionally, IGU decreased the intrathecal IL-6 level and infiltrating Th17 cells. The migration assay revealed reduced Th17 cell migration and IL-6 levels in the culture supernatant after IGU treatment. Collectively, IGU successfully mitigated the clinical signs of pEAE by suppressing Th17 migration through inhibition of IL-6 production by proinflammatory-activated glial cells.

Iguratimod reduces B-cell secretion of immunoglobulin to play a protective role in interstitial lung disease

OBJECTIVE

Our study aimed to investigate the effect of Iguratimod (IGU) on bleomycin (BLM)-induced interstitial lung disease (ILD).

METHODS

The pulmonary fibrosis model group mice were developed by intratracheal injection of BLM. Mice were divided into two groups at random: (1) Control group (BLM group) - endotracheal BLM (BLM, 3.5 mg/kg, Kayaku, Japan) plus an intraperitoneal injection of normal saline, and (2) BLM + IGU group - intratracheal BLM (same as the control group) + IGU intraperitoneal injection (50 mg/kg/d). The alveolar lavage fluid, histopathology/immunohistochemistry, imaging, and other tests were performed on days 7, 14, 21, and 28 after injection.

RESULTS

Lung function, including Compliance (Crs),Tissue damping (G), Static compliance (Cst), Inspiratory capacity (IC), Elastance (Ers), Tissue elastance (H) and Respiratory system resistance (Rrs) in mice, was improved by IGU. IGU reduced BLM-induced changes in pulmonary fibrosis and pulmonary inflammation, as shown in histological examination.Collagen production and inflammatory damage in the lungs caused by BLM were also reduced by IGU. IGU reduced the expression of immunoglobulin IgG and type I collagen in BLM-induced pulmonary fibrosis mice by inhibiting the production of B cells and immunoglobulin, and also delayed the deterioration of imaging changes.

CONCLUSION

IGU inhibits immunoglobulin secretion by B cells to relieve pulmonary inflammation and fibrosis. IGU also plays a protective role in the lung in ILD.

Iguratimod as a New Drug for Rheumatoid Arthritis: Current Landscape

Iguratimod (IGU) is a novel synthetic small molecule disease modified anti-rheumatic drug approved only in Japan and China up to date. IGU plays an important immunomodulatory role in the synovial tissue of rheumatoid arthritis by inhibiting the production of immunoglobulins and cytokines and regulating T lymphocyte subsets. IGU also regulates bone metabolism by stimulating bone formation while inhibiting osteoclast differentiation, migration, and bone resorption. In clinical trials, IGU was shown to be superior to placebo and not inferior to salazosulfapyridine. Combined therapy of IGU with other disease-modifying anti-rheumatic drugs showed significant improvements for disease activity. IGU has good efficacy and tolerance as an additional treatment for rheumatoid arthritis patients with inadequate response to methotrexate and biological disease-modifying anti-rheumatic drugs. In this review, we summarize current landscape on the mechanism of action of IGU and its clinical effectiveness and safety. It is expected that further translational studies on IGU will pave the road for wider application of IGU in the treatment of autoimmune diseases other than rheumatoid arthritis.

Iguratimod: a valuable remedy from the Asia Pacific region for ameliorating autoimmune diseases and protecting bone physiology

Autoimmune diseases are affected by complex pathophysiology involving several cell types, cytokines, antibodies, and mimicking factors. Different drugs are used to ameliorate these autoimmune reactions, including nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, antiantibodies, and small molecular drugs (DMARDs), and they are clinically in vogue for diseases such as rheumatoid arthritis (RA). Nevertheless, low cost-effectiveness, reduced efficacy, adverse effects, and patient nonresponse are unappealing factors driving the development of new drugs such as iguratimod. Iguratimod is primarily used to ameliorate RA in Japanese and Chinese clinics. However, its efficacy against other autoimmune ailments is also under intense investigation, and the number of investigations is becoming increasingly larger with each passing day. The articular structure comprises synovium, ligaments, and bone. The latter is more complex than the others since it regulates blood cells and autoimmunity in addition to providing skeletal support to the body. Therefore, its protection is also of prime importance in RA and other autoimmune diseases. Herein, we have highlighted the role of iguratimod in autoimmune diseases and bone protection. We suggest that iguratimod’s unique mode of action compared with that of other DMARDs and its good patient response makes it a suitable antirheumatic and bone-protecting drug.

Investigating the possible pain attenuating mechanisms of pregabalin in chronic constriction injury-induced neuropathic pain in rats

Aim of the study: The current study was aimed to investigate the neuropathic pain attenuating mechanism of pregabalin using chronic constriction injury (CCI) model in rats. Material and Methods: The sciatic nerve was ligated by placing four loose ligatures around it to induce neuropathic pain. The pain development in terms of cold allodynia, mechanical hyperalgesia, and heat hyperalgesia was assessed on the 7th and 14th day after surgery, using acetone drop, pinprick, and hot plate tests. On the 14th day after the injury, pain parameters were assessed 30 minutes after administration of pregabalin (30 mg/kg) and sodium nitroprusside (5 mg/kg) in CCI-subjected rats. Results: CCI led to induction of neuropathic pain, which was more prominent on 14th day in comparison to 7th day. A single administration of pregabalin and sodium nitroprusside on 14th day, markedly reduced pain parameters and increased serum nitrite levels. Pretreatment with L-NAME abolished neuropathic pain attenuating effects of pregabalin suggesting that pregabalin may increase the levels of nitric oxide to mitigate neuropathic pain. Pretreatment with naloxone significantly abrogated pain attenuating effects of pregabalin and sodium nitroprusside in CCI-subjected rats suggesting that pregabalin and nitric oxide-mediated analgesic action are mediated through release of endogenous opioids. Moreover, naloxone failed to modulate pregabalin-induced increase in nitric oxide levels suggesting that the opioid system does not control the nitric oxide levels, and opioids may be downstream modulators of nitric oxide. Conclusion: Pregabalin may increase the release of nitric oxide, which may increase the release of endogenous opioids to attenuate neuropathic pain in CCI subjected rats.

The add-on effectiveness and safety of iguratimod in patients with rheumatoid arthritis who showed an inadequate response to tocilizumab

Objectives: To evaluate the effectiveness of add-on iguratimod (IGU) in patients with rheumatoid arthritis (RA) who showed an inadequate response to tocilizumab (TCZ), especially patients who were intolerant of an effective dose of methotrexate (MTX). Methods: Thirty-one patients with RA (22 women, age 62.4 years, disease duration 13.8 years, prior TCZ duration 35.7 months, 25 intravenous [8 mg/kg/4 weeks] and 6 subcutaneous [162 mg/2 weeks] TCZ treatments, concomitant MTX 8.5 mg/week [35.5%], and prednisolone (PSL) 4.3 mg/day [25.8%]) who showed an inadequate response to TCZ (disease activity score assessing 28 joints with C-reactive protein [DAS28-CRP] 2.9, clinical disease activity index [CDAI] 15.0, 28 secondary inadequate responders) were treated with additional IGU (final dose 41.7 mg/day) and enrolled in this 24-week, multicenter, retrospective study. Results: Twenty-nine patients (93.5%) continued the treatment for 24 weeks (one dropped out for pneumonia and one for digestive symptoms). The TCZ and the concomitant dose and rate of conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) (MTX, salazosulfapyridine [SASP], and tacrolimus [TAC]) were not significantly changed during this period. Outcome measures improved significantly, as follows: DAS28-CRP from 2.9 to 1.7 (p < .001); CDAI from 15.0 to 6.0 (p < .001); modified Health Assessment Questionnaire (mHAQ) from 0.8 to 0.6 (p < .05); and rheumatoid factor (RF) from 382.1 to 240.3 IU/mL (p < .001). Using the EULAR criteria, 64.5% achieved a moderate response, and 51.6% achieved ACR 20 at 24 weeks. Conclusion: Adding IGU to inadequate responders to TCZ may be a promising and safe complementary treatment option.

Novel disease-modifying anti-rheumatic drug iguratimod suppresses chronic experimental autoimmune encephalomyelitis by down-regulating activation of macrophages/microglia through an NF-κB pathway

We aimed to elucidate the effects of iguratimod, a widely used anti-rheumatic drug with no severe side effects, on chronic experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Iguratimod was orally administered to mice immunised with myelin oligodendrocyte glycoprotein peptide 35–55. Preventive administration of iguratimod from the time of immunisation was found to markedly reduce the clinical severity of acute and chronic EAE. Pathologically, iguratimod treatment significantly reduced demyelination and infiltration of CD3⁺ T, F4/80⁺, and CD169⁺ cells into the spinal cord, and suppressed macrophage/microglia activation in the parenchyma at the acute and chronic stages compared with vehicle treatment. Therapeutic administration of iguratimod after the onset of clinical symptoms significantly ameliorated the clinical severity of chronic EAE and reduced demyelination, T helper (Th)1/Th17 cell infiltration, macrophage/microglia activation, and nuclear factor (NF)-κB p65 and cyclooxygenase-2 expression in the spinal cord. In vitro, iguratimod treatment inhibited nuclear translocation of NF-κB p65 and down-regulated pro-inflammatory responses in macrophages and microglia. Our results suggest that iguratimod ameliorates acute and chronic EAE by suppressing inflammatory cell infiltration and immune cell activation, partly through inhibition of NF-κB p65, supporting the therapeutic potential of this drug for not only acute, but also chronic MS.