Role of NLRP3 and NLRP1 inflammasomes signaling pathways in pathogenesis of rheumatoid arthritis

Role of some inflammasomes in rheumatoid arthritis patients in Egypt

AIM

This study aims to demonstrate the role of some inflammasomes genes: NLRC4 (the NLR family, CARD domain-containing protein 4), NLRP1 (NLR family, pyrin domain-containing 1), ASC (Apoptosis-associated speck-like protein containing a CARD), and CASPASE-1 in the pathogenesis of Rheumatoid arthritis (RA) in Egyptian population.

MAIN METHODS

The expression level of NLRC4, NLRP1, ASC, and CASPASE-1 within PBMCs isolated from all RA subjects by quantitative real-time PCR. GAPDH gene was used as a reference gene. Measurement of serum level of IL-1β and IL-18 was performed using ELISA.

KEY FINDINGS

Results showed dysregulated inflammasomes expression that may participate in the pathogenesis of the inflammatory process of the disease.

SIGNIFICANCE

Understanding the role of inflammasomes in RA pathogenesis helps in finding promising therapy for the treatment and management of this disease.

Inflammasomes in rheumatoid arthritis: a pilot study

BACKGROUND

The inflammasome plays an important role in rheumatoid arthritis (RA), which has rarely been systematically reported. The aim of this study was to understand whether the levels of inflammasomes were related to the severity of RA disease, which might provide a stronger theoretical basis for RA treatment.

METHODS

The mRNA expression levels of some inflammasomes and associated molecules, including IL-1beta and IL-18, in peripheral blood mononuclear cells (PBMCs) from 30 RA patients (n = 30) and 16 healthy control (HC) individuals were determined by quantitative real-time polymerase chain reaction (qRT‒PCR), and the levels of plasma IL-1beta and IL-18 were also measured by enzyme-linked immunosorbent assay (ELISA). Moreover, the clinical characteristics and laboratory results of the patients were collected and analyzed in this study.

RESULTS

The relative mRNA expression levels of NLRP3, NLRC4, AIM2, caspase-1, and IL-1beta were significantly higher and those of NLRP1, NLRP2 and NLRC5 were notably lower in the HC group than in the RA group. Moreover, the plasma IL-1beta and IL-18 levels were markedly increased in the RA group. Additionally, the mRNA level of AIM2 was negatively correlated with disease activity score 28 (DAS28) by stepwise linear regression analysis. erythrocyte sedimentation rate (ESR) was positively correlated with DAS28 by multiple linear regression analysis in the RA group.

CONCLUSIONS

These findings imply the critical role of NLRP3, NLRC4, AIM2, caspase-1 and plasma IL-1beta and IL-18 in the pathogenesis of RA patients, which provides potential targets for the treatment of 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.

Association of caspase-1 gene polymorphisms with rheumatoid arthritis risk in a Chinese Han population

The goals of present research are to investigate if the genetic polymorphisms in the caspase-1 (CASP1) gene are associated with the risk of rheumatoid arthritis (RA) and the clinical characteristics of the illness in Han patients from China. Our team studied the CASP1 rs2409062 A/G polymorphisms in 1095 healthy controls and 805 RA patients, while the genotype was identified via a custom-by-design 48-Plex single nucleotide polymorphism (SNP) scan™ Kit. The mRNA expression levels of the CASP1 in 40 RA cases and 40 healthy controls were detected by qRT-PCR, while blood plasma levels of the CASP1 in 40 RA cases and 40 paired controls measured via ELISA. Our research showed that the CASP1 rs2409062 A/G polymorphisms were related to an elevated risk for RA. By stratified analysis, our team discovered a remarkably elevated RA risk in females sufferers, age ≥ 55, CRP-positive, or DAS28 < 3.20. In contrast to the control group, the mean level of CASP1 protein in the plasma of RA cases rised significantly. Moreover, RA cases displayed significantly greater levels of CASP1 mRNA versus the control group (P < 0.05). Those outcomes reveal that the CASP1 rs2409062 A/G gene polymorphisms are associated with an elevated risk for RA in a Chinese Han population.

Role of NLRP3 Inflammasome in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by multi-articular, symmetrical and invasive arthritis resulting from immune system abnormalities involving T and B lymphocytes. Although significant progress has been made in the understanding of RA pathogenesis, the underlying mechanisms are not fully understood. Recent studies suggest that NLRP3 inflammasome, a regulator of inflammation, might play an important role in the development of RA. There have been increasing clinical and pre-clinical evidence showing the treatment of NLRP3/IL-1β in inflammatory diseases. To provide a foundation for the development of therapeutic strategies, we will briefly summarize the roles of NLRP3 inflammasome in RA and explore its potential clinical treatment.

The Role of Inflammasomes in Glomerulonephritis

The inflammasome is an immune multiprotein complex that activates pro-caspase 1 in response to inflammation-inducing stimuli and it leads to IL-1β and IL-18 proinflammatory cytokine production. NLRP1 and NLRP3 inflammasomes are the best characterized and they have been related to several autoimmune diseases. It is well known that the kidney expresses inflammasome genes, which can influence the development of some glomerulonephritis, such as lupus nephritis, ANCA glomerulonephritis, IgA nephropathy and anti-GBM nephropathy. Polymorphisms of these genes have also been described to play a role in autoimmune and kidney diseases. In this review, we describe the main characteristics, activation mechanisms, regulation and functions of the different inflammasomes. Moreover, we discuss the latest findings about the role of the inflammasome in several glomerulonephritis from three different points of view: in vitro, animal and human studies.

NOD-like receptors in autoimmune diseases

Autoimmune diseases are chronic immune diseases characterized by dysregulation of immune system, which ultimately results in a disruption in self-antigen tolerance. Cumulative data show that nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) play essential roles in various autoimmune diseases, such as inflammatory bowel disease (IBD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriasis, multiple sclerosis (MS), etc. NLR proteins, consisting of a C-terminal leucine-rich repeat (LRR), a central nucleotide-binding domain, and an N-terminal effector domain, form a group of pattern recognition receptors (PRRs) that mediate the immune response by specifically recognizing cellular pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) and triggering numerous signaling pathways, including RIP2 kinase, caspase-1, nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and so on. Based on their N-terminal domain, NLRs are divided into five subfamilies: NLRA, NLRB, NLRC, NLRP, and NLRX1. In this review, we briefly describe the structures and signaling pathways of NLRs, summarize the recent progress on NLR signaling in the occurrence and development of autoimmune diseases, as well as highlight numerous natural products and synthetic compounds targeting NLRs for the treatment of autoimmune diseases.

Sparstolonin B Exerts Therapeutic Effects on Collagen-Induced Arthritis by Inhibiting the NLRP3 Inflammasome and Reducing the Activity of α1,3-Fucosyltransferase

Objective. To explore the role of α1,3-fucosyltransferase in the mediation of rheumatoid arthritic inflammation, the protective effect of Sparstolonin B on rheumatoid arthritis (RA), and the mechanisms that regulate the NLRP3 inflammasome. Methods. Forty, weighing from 260-300 g, male Sprague-Dawley rats were randomly divided into the following groups: a sham operation group (Sham group), a rheumatoid arthritis model group (RA group), an RA+Sparstolonin B treatment group (RAS group), an RA+Iguratimod group (RAI group), and an RA+SsnB+NLRP3 inflammasome activator (Nigericin) group (RASN group); ten animals were allocated to each group. We determined the arthritis index for each group of rats, and pathological changes were evaluated by hematoxylin-eosin staining. We also used ELISAs to determine the serum levels of IL-17, IL-6, TNF-α, TGF-β, IL-18, and IL-1β. TUNEL staining was used to investigate apoptosis in synovial cells. IF was used to detect the release of ROS, ASC formation, and the expression levels of FucT-V and NLRP3. Western blotting was used to detect the protein expression levels of Bc1-2, Bax, TLR4, MYD88, NF-κB, pro-caspase-1, NLRP3, FucT-V, E-Selectin, and P-Selectin. We also performed in vitro experiments with Sparstolonin B and detected changes in 1,3-fucosyltransferase activity by ELISA. The pyroptosis-related phenotype, including ASC, was identified by immunofluorescence, while levels of NLRP-3, pro-IL-1, and pro-caspase-1 were detected by western blotting. Results. Sparstolonin B was showed to alleviate joint swelling in RA rats, inhibited inflammatory cell infiltration and the release of ROS, reduced damage caused by oxidative stress, and suppressed the rate of apoptosis in synovial cells. The administration of Sparstolonin B inhibited the secretion of IL-17 from Th17 cells and triggered the secretion of TGF-β from Treg cells, thus leading to the reduced expression of TLR4, MyD88, and NF-κB, and the suppression of TNF-α secretion. Moreover, Sparstolonin B downregulated the expression of NLRP3, inhibited ASC formation in vivo and in vitro, and reduced the levels of IL-18 and IL-1β. The expression levels of FucT-V, E-Selectin, and P-Selectin were also inhibited. Interestingly, these protective effects of Sparstolonin B could be blocked in RA rats by inhibiting the activation of the NLRP3 inflammasome. Conclusion. Sparstolonin B improved inflammatory responses and oxidative stress by inhibiting the NLRP3 inflammasome, inhibiting the expression of FucT-V and downregulating the TLR4/MYD88/NF-𝜅B signaling pathway in order to rescue RA.

Gasdermine E-Dependent Mitochondrial Pyroptotic Pathway in Dermatomyositis: A Possible Mechanism of Perifascicular Atrophy

Different mechanisms have been proposed to explain the pathological basis of perifascicular atrophy (PFA), a pathognomonic histologic feature of dermatomyositis (DM); however, the detailed mechanisms remain to be elucidated. There is mitochondrial dysfunction in PFA and expression of mitochondrial apoptosis molecules has been reported in DM. Overexpression of gasdermin E (GSDME) can turn mitochondrial apoptosis to mitochondrial pyroptosis, a newly characterized form of programmed cell death. We determined the expression of proteins involved in the caspase-3- and GSDME-dependent mitochondrial pyroptotic pathway, including BAX, BAK, cytochrome C, caspase-9, caspase-3, GSDME, and IL-1α, in biopsied muscles from DM and control patients. Immunohistochemical analysis showed that those markers were expressed in most fibers in PFA in DM. GSDME-positive and IL-1α-positive staining was mainly localized around punched-out vacuoles or sarcolemma. These markers were significantly upregulated at the protein and mRNA levels in DM versus controls. Our results suggest that caspase-3- and GSDME-dependent mitochondrial pyroptosis are involved in the pathogenetic mechanisms of PFA in DM and that targeting GSDME-dependent mitochondrial pyroptosis may be an effective therapeutic approach for this condition.

To protect or adversely affect? The dichotomous role of the NLRP1 inflammasome in human disease

NLRP1 is an inflammasome forming pattern recognition receptor (PRR). When activated by pathogen- and damage- associated molecular patterns (PAMPS/DAMPS), NLRP1 inflammasome formation leads to inflammation through the production of proinflammatory cytokines IL-18 and IL-1β. As with other inflammasome forming NLR family members, NLRP1 also regulates cell death processes, termed pyroptosis. The domain structure of NLRP1 differs between mice and humans, making it possible for the function of the inflammasome to differ between species and adds complexity to the study of this NLR family member. In humans, mutations in both coding and non-coding regions of the NLRP1 gene are linked to a variety of diseases. Likewise, interruption of NLRP1 inhibitors or changes in the prevalence of NLRP1 activators can also impact disease pathobiology. Adding to its complexity, the NLRP1 inflammasome plays a dichotomous role in human diseases, functioning to either attenuate or augment miscellaneous biological processes in a tissue specific manner. For example, NLRP1 plays a protective role in the gastrointestinal tract by modulating the microbiome composition; however, it augments neurological disorders, cardio-pulmonary diseases, and cancer through promoting inflammation. Thus, it is critical that the role of NLRP1 in each of these disease processes be robustly defined. In this review, we summarize the current research landscape to provide a better understanding of the mechanisms associated with NLRP1 function and dysfunction in human disease pathobiology. We propose that a better understanding of these mechanisms will ultimately result in improved insight into immune system dysfunction and therapeutic strategies targeting inflammasome function in multiple human diseases.

Pien Tze Huang alleviate the joint inflammation in collagen-induced arthritis mice

Background

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovitis. Pien Tze Huang (PZH) is a Chinese patent medicine with anti-inflammatory and immunomodulatory effects. However, whether PZH could be used in RA therapy is still unknown. Therefore, this study aimed to explore the therapeutic effect and the potential mechanism of PZH on collagen-induced arthritis (CIA) mice.

Methods

Male DBA/1J mice were used to establish an animal model of CIA and then treated with different doses of PZH for 4 weeks. The therapeutic effect of PZH on CIA mice was evaluated by arthritis score, pathological staining, and detecting the levels of inflammatory factors in serum and joints. To investigate its possible mechanism, the activity of NF-κB signaling pathway, NLRP3 inflammasome and the level of A20 were detected.

Results

The results showed that PZH could alleviate the erythema and swelling of hind paws of CIA mice, improve the pathological conditions of joint and decrease the production of IL-1β, IL-6 and IL-17 in serum and joints. Furthermore, PZH could significantly inhibit the activity of NF-κB signaling pathway and NLRP3 inflammasome in the ankle joint of CIA mice compared with the model group. It also increased the level of A20 in the ankle joint of CIA mice.

Conclusion

This study indicated that PZH could alleviate the joint inflammation of CIA mice, and the mechanism might be related to the regulation of NF-κB signaling pathway and NLRP3 inflammasome.

Dexmedetomidine inhibits the invasion, migration, and inflammation of rheumatoid arthritis fibroblast-like synoviocytes by reducing the expression of NLRC5

Rheumatoid arthritis (RA) is a chronic, autoimmune disease characterized by inflammatory synovitis, but its pathogenesis remains unclear. NLRC5 is a newly discovered member of the NLR family that is effective in regulating autoimmunity, inflammatory responses, and cell death processes. Dexmedetomidine (DEX) has been reported to have a variety of pharmacological effects, including anti-inflammatory and analgesic effects. However, the role of DEX in RA has not been explored. In adjuvant-induced arthritis (AA) rat models, DEX (10 μg/kg and 20 μg/kg) reduced the pathological score, the arthritis score, paw swelling volume, and the serum levels of IL-1β, IL-6, IL-17A, and TNF-α. Moreover, by using Western blot and real-time quantitative PCR (RT-qPCR), it was demonstrated that DEX can inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9 and P-P65 in the synovial tissue of AA rats. In human rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs), DEX (250 nM and 500 nM) was found to inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65 following stimulation with TNF-α. Moreover, DEX can inhibit the invasion and migration of RA-FLSs stimulated by TNF-α. Finally, the expression of NLRC5 in RA-FLSs and AA rat models was also reduced by DEX. After silencing NLRC5 in RA-FLSs, the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65, as well as the invasion and migration of cells, were significantly reduced. These results indicate that DEX inhibits the invasion, migration, and inflammation of RA-FLSs by reducing the expression of NLRC5 and inhibiting the NF-κB activation.

Inflammasomes and autoimmune and rheumatic diseases: A comprehensive review

Inflammasomes are a multi-protein platform forming a part of the innate immune system. Inflammasomes are at standby status and can be activated when needed. Inflammasome activation is an important mechanism for the production of active interleukin (IL)-1β and IL-18, which have important roles to instruct adaptive immunity. Active forms of inflammasomes trigger a series of inflammatory cascades and lead to the differentiation and polarization of naïve T cells and secretion of various cytokines, which can induce various kinds of autoimmune and rheumatic diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), gout, Sjögren's syndrome, Behçet's disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and IgA vasculitis (former Henoch-Schönlein purpura ). In this review, we summarize studies published on inflammasomes and review their roles in various autoimmune diseases. Understanding of the role of inflammasomes may facilitate the diagnosis of autoimmune diseases and the development of tailored therapies in the future.

TNF-α/calreticulin dual signaling induced NLRP3 inflammasome activation associated with HuR nucleocytoplasmic shuttling in rheumatoid arthritis

OBJECTIVE

The present study was undertaken to validate whether TNF-α and calreticulin (CRT) serve as dual signaling to activate nucleotide-binding oligomerization domain-, leucine-rich repeat- and pyrin domain-containing 3 (NLRP3) inflammasome in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) and HUVECs. The effect of human antigen R (HuR) in NLRP3 inflammasome activation was also explored in RA FLS.

METHODS

Immunofluorescence was used to determine the expression of NLRP3 and adaptor protein apoptosis associated speck-like protein containing a CARD (ASC) in RA synovial tissue and HuR location in RA FLS. Western blot and quantitative real-time PCR were employed to measure the priming effect of NLRP3 inflammasome in cells and HuR expression in synovial tissue. The concentrations of IL-1β and IL-18 were detected by enzyme linked immunosorbent assay. Immunohistochemistry was used to visualize the expression of HuR in synovial tissue. HuR knockdown in RA FLS was achieved by siRNA-mediated gene silencing.

RESULTS

Higher expression of NLRP3 and ASC in RA synovial tissue than those in osteoarthritis was detected. The staining of NLRP3, ASC and cleaved IL-1β were observed in FLS and vascular endothelial cells in RA synovium. Expression of NLRP3 and pro-IL-1β in RA FLS and HUVECs treated with TNF-α was increased. The pro-IL-18 expression was also enhanced in HUVECs, but not in RA FLS. TNF-α/CRT dual stimulation of cells gave rise to caspase-1 p20 expression and the secretion of IL-1β. The secreted IL-18 was also elevated in HUVECs but not in RA FLS. HuR expression was significantly elevated in RA synovial tissue. TNF-α initiated the nucleocytoplasmic shuttling of HuR in both FLS and HUVECs. The knockdown of HuR in FLS incubated with TNF-α led to reduced caspase-1 p20 protein expression and further resulted in decreased secretion of IL-1β in the presence of CRT.

CONCLUSIONS

TNF-α/CRT dual signaling induced NLRP3 inflammasome activation, which could be suppressed by HuR knockdown presumably due to the block of HuR translocating from nucleus to cytoplasma.

NLRP3: A promising therapeutic target for autoimmune diseases

NLRP3, a member of nucleotide-binding domain-(NOD) like receptor family, can be found in large varieties of immune and non-immune cells. Upon activation, the NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1 would assemble into a multimeric protein, called the NLRP3 inflammasome. Then the inflammasome promotes inflammation (through specific cleavage and production of bioactive IL-1β and IL-18) and pyroptotic cell death. Previous studies have indicated the importance of NLRP3 in regulating innate immunity. Recently, numerous studies have revealed their significance in autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc) and inflammatory bowel disease (IBD). In this review, we will briefly discuss the biological features of NLRP3 and summarize the recent progression of the involvement of NLRP3 in the development and pathogenesis of autoimmune diseases, as well as its clinical implications and therapeutic potential.

Downregulated NLRP3 and NLRP1 inflammasomes signaling pathways in the development and progression of type 1 diabetes mellitus

BACKGROUND

NLRP3 and NLRP1 inflammasomes signaling pathways may play an important role in the development and progression of type 1 diabetes mellitus (T1DM). However, relative research is rare.

METHODS

The blood mononuclear cells (PBMCs) and granulocytes (GCs) were collected from T1DM patients. The mRNA and protein expression levels were detected by qRT-PCR and Western blotting, respectively. The NLRP3/NLRP1was knocked down by transfected with siRNA, or ovexpressed by infected with lentiviral vectors in PBMCs and GCs from non obese diabetic (NOD) mice, respectively. The occurrence of diabetes was evaluated and the intraperitoneal glucose tolerance was tested in NOD mice with IL-1 receptor-associated kinase-M deficiency (IRAK-M^-/-). The pancreas and lymphonodus of IRAK-M^-/- NOD mice were also collected for detection of NLRP3/NLRP1 expression.

RESULTS

NLRP3, NLRP1, Caspase-1and IL-1β were significantly downregulated in the PBMCs and GCs of patients with T1DM, and NLRP3 and NLRP1 were markedly downregulated in T1DM patients with DKA compared to that with ND and CC. Further study indicated that IL-1β mRNA expression level was positively correlated with the expression levels of NLRP3, NLRP1 and Caspase-1. Besides, NLRP3/NLRP1 knockdown decreased the expression levels of Caspase-1 and IL-1β; whereas NLRP3/NLRP1 overexpression increased the expression levels of Caspase-1 and IL-1β in vitro. IRAK-M^-/- NOD mice had early onset and rapid progression of T1DM, and weak glucose tolerance, which was regarded as an early T1D mouse model. The mRNA expression levels of NLRP3, NLRP1, Caspase-1and IL-1β in the pancreas and lymphonodus of IRAK-M^-/- NOD mice were significantly higher compared to that of IRAK-M^+/+ NOD mice.

CONCLUSION

NLRP3 and NLRP1 inflammasomes signaling pathways were associated with the development and progression of T1DM, which response as protective factors in the early stage of T1DM.

Sex- and disease-specific inflammasome signatures in circulating blood leukocytes of patients with abdominal aortic aneurysm

Male sex is a risk factor for abdominal aortic aneurysm (AAA). Within the AAA adventitia, infiltrating leukocytes express high levels of inflammasome components. To further elucidate the role of inflammatory cells in the pathogenesis of AAA, we here addressed expression and functionality of inflammasome components in peripheral blood mononuclear cells (PBMC) of AAA patients in association with sex. PBMC and plasma were isolated from 100 vascular patients, including 34 pairs of AAA patients and age/sex-matched non-AAA patients. Male PBMC were found to express significantly higher mRNA levels of AIM2, NLRP3, ASC (PYCARD), CASP1, CASP5, and IL1B (all P < 0.0001) than female PBMC. Within the male patients, PBMC of AAA patients displayed increased mRNA levels of NLRP3 (P = 0.044), CASP1 (P = 0.032) and IL1B (P = 0.0004) compared to matched non-AAA PBMC, whereas there was no difference between female AAA and non-AAA patients. The relative protein level of NLRP3 was significantly lower in PBMC lysates from all AAA patients than in matched controls (P = 0.038), whereas AIM2 and active Caspase-1 (p10) protein levels were significantly increased (P = 0.014 and P = 0.049). ELISA revealed significantly increased IL-1α (mean = 6.34 vs 0.01 pg/ml) and IL-1β plasma levels (mean = 12.07 vs. 0.04 pg/ml) in AAA patients. The data indicate that male PBMC display a systemic proinflammatory state with primed inflammasomes that may contribute to AAA-pathogenesis. The AAA-specific inflammasome activation pattern suggests differential regulation of the sensors AIM2 and NLRP3 in inflammatory cells of AAA patients.

Zisheng Shenqi decoction ameliorates monosodium urate crystal-induced gouty arthritis in rats through anti-inflammatory and anti-oxidative effects

Based on traditional Chinese medicinal theories on gouty arthritis, Zisheng Shenqi decoction (ZSD), a novel Chinese medicinal formula, was developed due to its multiple functions, including reinforcing renal function, promoting blood circulation and relieving pain. In the present study, the effect of ZSD on monosodium urate (MSU) crystal-induced gouty arthritis in rats was investigated and the underlying mechanisms were examined. The data from these investigations showed that the injection of MSU crystals into the ankle joint cavity caused significant elevations in ankle swelling and inflammatory cell infiltration into the synovium, whereas these abnormal changes were markedly suppressed by oral administration of ZSD (40 mg/kg) for 7 days. Mechanically, ZSD treatment prevented MSU crystal-induced inflammatory responses, as evidenced by downregulation in the expression levels of NACHT domain, leucine-rich repeat and pyrin domain containing protein (NALP) 1 and NALP6 inflammasomes, decreased serum levels of tumor necrosis factor-α and interleukin-1β, and inhibited activation of nuclear factor-κB. In addition, ZSD administration markedly enhanced the anti-oxidant status in MSU crystal-induced rats by the increase in the activities of superoxide dismutase and glutathione peroxidase, and the levels of reduced glutathione. These results indicated that ZSD effectively prevented MSU crystal-induced gouty arthritis via modulating multiple anti-oxidative and anti-inflammatory pathways, suggesting a promising herbal formula for the prevention and treatment of gouty arthritis.

NLRP3 Inflammasome Plays an Important Role in the Pathogenesis of Collagen-Induced Arthritis

Objective. To investigate the relationship between NLRP3 and the pathogenesis of collagen-induced arthritis. Methods. We used the collagen-induced arthritis (CIA) mouse model. The mice were divided into two groups: the model group (CIA, n = 16) and the control group (Normal, n = 8). The mice were sacrificed seven weeks after immunization. The arthritis score and imaging evaluation (X-rays, Micro-CT, and MRI) were performed. Synovial tissue NLRP3 expression and peripheral blood cytokine levels were analyzed. Results. The arthritis score (6.00 ± 2.52), imaging score (4.63 ± 0.92), and synovial tissue NLRP3 expression (4.00 ± 2.03) significantly increased in the CIA mice. The expression of synovial NLRP3 was positively correlated with arthritis clinical and radiographic scores (r = 0.792 and r = 0.669, resp.). Conclusions. The synovial NLRP3 expression increased at the early onset of RA. Synovial NLRP3 expression level was correlated with the clinical arthritis severity and extent of radiological destruction, suggesting that NLRP3 is involved in the pathogenesis of RA.