Advances in rheumatoid arthritis animal models

Pathological pathway analysis in an experimental rheumatoid arthritis model and the tissue repair effect of acupuncture at ST36

Rheumatoid arthritis (RA) is an autoimmune disease that generally affects the joints. In the face of inflammation-induced cartilage and bone damage, RA treatment remains insufficient. While research evidence indicates that acupuncture can exert anti-inflammatory and analgesic effects, improve the joint function of RA patients, and delay the disease, data on whether it can promote RA repair are lacking. Findings from the present work demonstrated that both the antigen-induced arthritis (AIA) and collagen-induced arthritis (CIA) models can simulate joint swelling of RA. The AIA model was more stable than the CIA model, with a higher incidence of successful arthritis modeling. Moreover, the AIA mice model could simulate the signal molecules and related pathological processes of the autoimmune response in RA, as well as major pathways related to RA and antigen immune response mechanisms. Manual acupuncture (MA) at Zusanli (ST36) significantly improved paw redness and swelling, pain, and inflammatory cell infiltration in the joints in AIA mice. The therapeutic effect of MA on AIA is achieved primarily through the regulation of steroid hormone biosynthesis, cell metabolism, and tissue repair processes. MA at ST36 can increase the gene contents of tissue repair growth factors, including PEG3, GADD45A, GDF5, FGF5, SOX2, and ATP6V1C2 in the inflammatory side joints of AIA mice, as well as the gene expression of the anti-inflammatory cytokine IL-10. In conclusion, acupuncture may alleviate RA in the joints via modulating the tissue healing process.

Differentiated embryonic chondrocyte expressed gene-1 is a central signaling component in the development of collagen-induced rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases and affects almost 1% of the population. Differentiated embryo-chondrocyte expressed gene-1 (DEC1) has been associated with both osteogenesis and osteoclastogenesis. RA condition is marked by inflammatory hyperplasia, and DEC1 is known to support inflammatory reactions and implicated in antiapoptosis and cell invasion. Here, our goal was to test the hypothesis that DEC1 enhances RA development induced by collagen-induced arthritis (CIA), a well-recognized protocol for developing RA animal models. DEC1^+/+ and DEC1^-/- mice were subjected to CIA protocol, and the development of RA condition was monitored. We found that CIA robustly induced RA phenotypes (e.g., synovial hyperplasia) and greatly increased the expression of proinflammatory cytokines such as TNF-α. However, these changes were detected in DEC1^+/+ but not DEC1^-/- mice. Interestingly, these very cytokines strongly induced DEC1, and such a dual role of DEC1, as an inducer for and being induced by proinflammatory cytokines, constitutes a DEC1-amplifying circuit for inflammation. Knockdown of DEC1 in human MH7A cells strongly decreased cell migration and invasion as well as the expression of genes related to RA phenotypes. The combination of DEC1-directed migration and invasion in vitro with synovial hyperplasia in vivo mechanistically establishes cellular bases on how DEC1 is involved in the development of RA phenotypes. In addition to inflammatory signaling, DEC1 functionally interacted with PI3KCA(p110α)/Akt/GSK3β, Wnt/β-catenin, and NFATc1. Such engagement in multiple signaling pathways suggests that DEC1 plays coordinated and integral roles in developing RA, one of the most common autoimmune diseases.

Therapeutic potential of targeted-gold nanospheres on collagen-induced arthritis in rats

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes functional disability due to bone destruction and severe joint pain. Current anti-rheumatic treatments develop severe complications and do not provide complete remission. Gold nanoparticles (AuNPs) have garnered attention because of their unique physical and chemical properties. In this study, we have evaluated the therapeutic effects of gold nanospheres (AuNSs) with two different ligands (targeted-nanoparticles) against collagen-induced arthritis (CIA) and compared the outcomes with conventional methotrexate (MTX) and biological (infliximab) treatments. Clinical evaluation was performed by radiographic and histological examinations. The bioaccumulation of AuNSs in vital organs was assessed. The mechanistic studies targeting pro-inflammatory/anti-inflammatory and angiogenic mediators' expressions were performed. Radiographic examination showed that the targeted AuNSs reduced joint space narrowing and bone erosion. Moreover, histopathological examination of rat ankle joints demonstrated that targeted AuNSs reduce bone and cartilage degeneration/inflammation. Gold nanospheres-conjugated with nucleus localized peptide (nuclear membrane-targeted) (AuNSs@NLS) has resolved bone destruction and inflammation compared to gold nanospheres-conjugated at polyethylene glycol (AuNSs@PEG). Although the AuNSs accumulated in different organs in both cases, they did not induce any toxicity or tissue damage. The two different targeted AuNSs significantly suppress inflammatory and angiogenic mediators' expression and induced anti-inflammatory cytokine production, but the AuNSs@NLS had superior therapeutic efficacy. In conclusion, these results suggested that nuclear membrane-targeted AuNSs effectively attenuated arthritis progression without systemic side effects.

Inhibition of Ras GTPases prevents Collagen-Induced Arthritis by Reducing the Generation of Pathogenic CD4+ T Cells and the Hyposialylation of Autoantibodies

OBJECTIVE

RasGTPases are master regulators of multiple intracellular signaling cascades. Perturbation of this pathway has been implicated in the pathogenesis of rheumatoid arthritis (RA). In this study we aimed to define the therapeutic potential of a novel RasGTPases inhibitor, farnesylthiosalicylate (FTS), in the preclinical mouse model of collagen-induced arthritis (CIA) and better delineate its immunomodulatory effects both ex vivo and in the mouse.

METHODS

We analyzed in vitro the immunomodulatory effects of FTS on various CD4⁺ T-cell functions such as activation, proliferation, T-helper polarization, and production of proinflammatory cytokines. Using the CIA model, we further determined the efficacy of FTS to inhibit clinical, histopathologic, and diverse immunological outcomes of arthritis.

RESULTS

FTS treatment of CD4⁺ T cells in vitro effectively targeted distinct kinases (extracellular signal-regulated kinase 1/2, p38, protein kinase B/AKT, and mammalian target of rapamycin), the production of interleukin (IL)-17A, IL-22, and granulocyte-macrophage colony-stimulating factor, and Th17 polarization. FTS therapy in the mouse CIA model significantly reduced clinical disease severity and joint inflammation/damage by histology. Importantly, FTS suppressed the in vivo induction of splenic IL-17⁺ IL-22⁺ Th17 cells and the secretion of proinflammatory cytokines. The production of pathogenic autoantibodies and their abnormal hyposialylation was significantly attenuated by FTS therapy. Importantly, in vivo generation of collagen type-II specific effector CD4⁺ T cells was likewise repressed by FTS therapy.

CONCLUSION

The RasGTPases inhibitor FTS attenuates the production of proinflammatory cytokines by in vitro-activated T cells and is a potent immunomodulatory compound in the CIA model, primarily targeting the generation of autoreactive Th17 cells and the production of autoantibodies and their subsequent pathogenic hyposialylation.

Understanding the Molecular Mechanisms Underlying the Pathogenesis of Arthritis Pain Using Animal Models

Arthritis, including osteoarthritis (OA) and rheumatoid arthritis (RA), is the leading cause of years lived with disability (YLD) worldwide. Although pain is the cardinal symptom of arthritis, which is directly related to function and quality of life, the elucidation of the mechanism underlying the pathogenesis of pain in arthritis has lagged behind other areas, such as inflammation control and regulation of autoimmunity. The lack of therapeutics for optimal pain management is partially responsible for the current epidemic of opioid and narcotic abuse. Recent advances in animal experimentation and molecular biology have led to significant progress in our understanding of arthritis pain. Despite the inherent problems in the extrapolation of data gained from animal pain studies to arthritis in human patients, the critical assessment of molecular mediators and translational studies would help to define the relevance of novel therapeutic targets for the treatment of arthritis pain. This review discusses biological and molecular mechanisms underlying the pathogenesis of arthritis pain determined in animal models of OA and RA, along with the methodologies used.

RTD-1 therapeutically normalizes synovial gene signatures in rat autoimmune arthritis and suppresses proinflammatory mediators in RA synovial fibroblasts

Rhesus theta defensin-1 (RTD-1), a macrocyclic immunomodulatory host defense peptide from Old World monkeys, is therapeutic in pristane-induced arthritis (PIA) in rats, a model of rheumatoid arthritis (RA). RNA-sequence (RNA-Seq) analysis was used to interrogate the changes in gene expression in PIA rats, which identified 617 differentially expressed genes (DEGs) in PIA synovial tissue of diseased rats. Upstream regulator analysis showed upregulation of gene expression pathways regulated by TNF, IL1B, IL6, proinflammatory cytokines, and matrix metalloproteases (MMPs) involved in RA. In contrast, ligand-dependent nuclear receptors like the liver X-receptors NR1H2 and NR1H3 and peroxisome proliferator-activated receptor gamma (PPARG) were downregulated in arthritic synovia. Daily RTD-1 treatment of PIA rats for 1-5 days following disease presentation modulated 340 of the 617 disease genes, and synovial gene expression in PIA rats treated 5 days with RTD-1 closely resembled the gene signature of naive synovium. Systemic RTD-1 inhibited proinflammatory upstream regulators such as TNF, IL1, and IL6 and activated antiarthritic ligand-dependent nuclear receptor pathways, including PPARG, NR1H2, and NR1H3, that were suppressed in untreated PIA rats. RTD-1 also inhibited proinflammatory responses in IL-1β-stimulated human RA fibroblast-like synoviocytes (FLS) in vitro and diminished expression of human orthologs of disease genes that are induced in rat PIA synovium. Thus, the antiarthritic mechanisms of systemic RTD-1 include homeostatic regulation of arthritogenic gene networks in a manner that correlates temporally with clinical resolution of rat PIA.

Selective Sexual Dimorphisms in Musculoskeletal and Cardiopulmonary Pathologic Manifestations and Mortality Incidence in the Tumor Necrosis Factor-Transgenic Mouse Model of Rheumatoid Arthritis

OBJECTIVE

To examine and quantify the sexual dimorphism in pathologic features manifested in the musculoskeletal and cardiopulmonary systems and incidence of mortality in the tumor necrosis factor-transgenic (TNF-Tg; Tg3647 strain) mouse model of inflammatory erosive arthritis.

METHODS

Kaplan-Meier survival estimates were determined in male and female Tg3647 mice and sex-matched wild-type (WT) littermate mice. Longitudinal and cross-sectional pathologic outcomes in the musculoskeletal and cardiopulmonary systems were assessed via ultrasound, micro-computed tomography, grip strength measurements, histologic and serologic analyses, flow cytometry, and skeletal muscle physiologic measures.

RESULTS

Compared to male Tg3647 mice (n = 30), female Tg3647 mice (n = 34) had significantly shorter lifespans (P < 0.001) and exhibited the following pathologic features (n = 4-6 per group; P < 0.05 versus male Tg3647 littermates): gross deficits in body mass and muscle weight, early-onset inflammatory arthritis with severity of end-stage arthritis that was as severe as that seen in male transgenic mice, and early onset and increased severity of inflammatory interstitial lung disease (ILD). Histologically, the ILD observed in Tg3647 mice was characterized by inflammatory cell accumulation and pulmonary arteriole thickening, which was concomitant with the presence of right ventricular hypertrophy, a feature that was also more severe in the female compared to male Tg3647 mice (P < 0.05). No sexual dimorphisms in TNF-induced deficient grip strength, axial skeletal growth, or bone loss were found. Globally, the extent of the pathologic changes observed in female Tg3647 mice was greater than that observed in male Tg3647 mice when each group was compared to their sex-matched WT littermates.

CONCLUSION

These findings indicate that TNF selectively drives the early onset of arthritis and progression of pathologic changes in the cardiopulmonary system in female Tg3647 mice. These results in the Tg3647 mouse identify it as a suitable model to better understand the mechanisms underlying sexual dimorphism and cardiopulmonary disease in the setting of inflammatory arthritis and other connective tissue diseases.

Terpenes as possible drugs for the mitigation of arthritic symptoms - A systematic review

BACKGROUND

Arthritis is a syndrome associated with exacerbated inflammation, joint destruction and chronic pain and disability. Chronic treatment of arthritis is associated with several side effects and high abandonment. Therefore, there has been an ongoing search for alternative treatments to overcome these problems.

PURPOSE

Natural products, which are already widely used for their biological, cosmetic and pharmacotechnic properties, are a possible source for new drugs. Terpenes, a large class of organic compounds produced mainly by plants and trees, are a promising natural product and have already been shown to be effective in treating chronic pain, particularly of an inflammatory origin.

STUDY DESIGN AND METHODS

This review identifies the main terpenes with anti-arthritic activity reported in the last 10 years. A survey was conducted between December 2017 and June 2018 in the PUBMED, SCOPUS and Science Direct databases using combinations of the descriptors terpenes, arthritis and inflammation.

RESULTS

The results showed that terpenes have promising biological effects in relation to the treatment of arthritis, with the 24 terpenes identified in our survey being effective in the modulation of inflammatory mediators important to the physiopathology of arthritis, such as IL-6, IL-17, TNF-α, NFκB, and COX-2, among others. It is important to note that most of the studies used animal models, which limits, at least in part, the direct translation to humans of the experimental evidence produced by the studies.

CONCLUSION

Together, our finds suggest that terpenes can modulate the immuno-regulatory and destructive tissue events that underlie the clinical presentation and the progression of arthritis and are worthy of further clinical investigation.

Applications and potential mechanisms of herbal medicines for rheumatoid arthritis treatment: a systematic review

In this review, we systematically discuss the role of traditional Chinese medicine (TCM) in rheumatoid arthritis (RA) disease treatment. TCM classifies the subtypes of RA through its own theoretical method, which is beneficial for more accurate diagnosis and treatment with Chinese herbal medicines (CHMs) that are more suitable for different syndromes. TCM mainly uses a flexible combination of CHMs to play an important role in RA treatment. The main components of these extracts can be subdivided into alkaloids, flavonoids, triterpenes, saponins and other compounds. Using a platform of transgenic and induced arthritis models, we explore the potential mechanisms of TCM against RA with the help of omics analysis techniques and methods. These mechanisms are mainly CHM and its extracts can inhibit RA patients and experimental animal models, including synovitis, vascular proliferation and bone injury; this involves many biological signal exchange targets and pathways. In conclusion, the role of TCM in RA treatment mainly involves reducing the expression and secretion of pro-inflammatory factors, thus decreasing the degree of abnormal immune response.

In this review, we systematically discuss the role of traditional Chinese medicine (TCM) in rheumatoid arthritis (RA) disease treatment.

Complex Role of Capsaicin-Sensitive Afferents in the Collagen Antibody-Induced Autoimmune Arthritis of the Mouse

Capsaicin-sensitive afferents have complex regulatory functions in the joints orchestrated via neuropeptides. This study aimed to determine their role in the collagen-antibody induced rheumatoid arthritis model. Capsaicin-sensitive nerves were defunctionalized by the capsaicin receptor agonist resiniferatoxin in C57Bl/6 mice. Arthritis was induced by the ArithroMab antibody cocktail and adjuvant. Arthritis was monitored by measuring body weight, joint edema by plethysmometry, arthritis severity by clinical scoring, mechanonociceptive threshold by plantar esthesiometry, thermonociceptive threshold by hot plate, cold tolerance by paw withdrawal latency from 0 °C water. Grasping ability was determined by the wire-grid grip test. Bone structure was evaluated by in vivo micro-CT and histology. Arthritic animals developed a modest joint edema, mechanical and cold hyperalgesia, weight loss, and a diminished grasping function, while thermal hyperalgesia is absent in the model. Desensitised mice displayed reduced arthritis severity, edema, and mechanical hyperalgesia, however, cold hyperalgesia was significantly greater in this group. Arthritic controls displayed a transient decrease of bone volume and an increased porosity, while bone density and trabecularity increased in desensitised mice. The activation of capsaicin-sensitive afferents increases joint inflammation and mechanical hyperalgesia, but decreases cold allodynia. It also affects inflammatory bone structural changes by promoting bone resorption.

Modeling Sex Differences in Anti-inflammatory Effects of Dexamethasone in Arthritic Rats

PURPOSE

Collagen-induced arthritic (CIA) rats are used commonly for preclinical pharmacologic research into rheumatoid arthritis (RA). Dexamethasone (DEX), a potent corticosteroid (CS), remains an important component in combination therapy for RA. Although sex differences in RA and CS pharmacokinetics/pharmacodynamics (PK/PD) have been documented in humans, there has been no such comprehensive evaluation of sex differences in CIA rats.

METHODS

Paw size measurements were obtained for males and females from four groups of animals: healthy controls, non-drug treated arthritic animals, and both 0.225 and 2.25 mg/kg DEX-treated arthritic animals. A turnover model for disease progression, minimal PBPK model for drug concentrations, and inhibitory indirect response model were applied using population PK/PD modeling.

RESULTS

The clearances of DEX were 43% greater in males, but other PK parameters were similar. The temporal profiles of paw swelling exhibited earlier progression, peak edema times, and disease remission in females. DEX suppressed paw edema well in both males and females with similar capacity (I_max) values (=1.0), but DEX potency was less in females with higher IC₅₀ values (0.101 versus 0.015 ng/mL).

CONCLUSIONS

The pharmacology of DEX was well characterized in CIA rats. This study addresses knowledge gaps about sex differences and can be a guide for more mechanistic assessment of sex, drug, and disease differences in RA.

A Microdialysis in Adjuvant Arthritic Rats for Pharmacokinetics⁻Pharmacodynamics Modeling Study of Geniposide with Determination of Drug Concentration and Efficacy Levels in Dialysate

Microdialysis, a sampling method for pharmacokinetics–pharmacodynamics (PK–PD) modeling in preclinical and clinical studies, is a convenient in vivo sampling technique. Geniposide (GE), an iridoid glycoside compound, is the major active ingredient of Gardenia jasminoides Ellis fruit which has an anti-inflammatory effect. In this study, an articular cavity microdialysis sampling system for adjuvant arthritic (AA) rats was established to study the effect of GE on the release of prostaglandin E₂ (PGE₂) in AA rats induced by Freund’s complete adjuvant (FCA). An UHPLC-MS/MS method was developed to determine the concentrations of GE and PGE₂ in the dialysate. Through the determination of drug concentrations and PGE₂ efficacy levels in the dialysate, the developed methods were successfully applied to set up concentration–time and effect–time profiles followed by PK–PD modeling of GE’s effect on decreasing PGE₂ release after oral administration of GE. The effect was well described by the developed PK–PD modeling, indicating that GE may play an anti-inflammatory role via decreasing AA-induced elevated PGE₂ levels. In the selection of suitable endogenous small molecules as effect markers, the establishment of AA rat joint-cavity microdialysis is an attractive technique for rational PK–PD studies.

Experimental animal models for rheumatoid arthritis

Rheumatoid Arthritis (RA) is an autoimmune systemic disorder of unknown etiology and is characterized by chronic inflammation and synovial infiltration of immune cells. RA is associated with decreased life expectancy and quality of life. The research on RA is greatly simplified by animal models that help us to investigate the complex system involving inflammation, immunological tolerance and autoimmunity. The animal models of RA with a proven track record of predictability for efficacy in humans include: collagen type II induced arthritis in rats as well as mice, adjuvant induced arthritis in rats and antigen induced arthritis in several species. The development of novel treatments for RA requires the interplay between clinical observations and studies in animal models. However, each model features a different mechanism driving the disease expression; the benefits of each should be evaluated carefully in making the appropriate choice for the scientific problem to be investigated. In this review article, we focus on animal models of arthritis induced in various species along with the genetic models. The review also discussed the similarity and dissimilarities with respect to human RA.

Cholinergic modulation of the immune system presents new approaches for treating inflammation

The nervous system and immune system have broad and overlapping distributions in the body, and interactions of these ubiquitous systems are central to the field of neuroimmunology. Over the past two decades, there has been explosive growth in our understanding of neuroanatomical, cellular, and molecular mechanisms that mediate central modulation of immune functions through the autonomic nervous system. A major catalyst for growth in this field was the discovery that vagal nerve stimulation (VNS) caused a prominent attenuation of the systemic inflammatory response evoked by endotoxin in experimental animals. This effect was mediated by acetylcholine (ACh) stimulation of nicotinic receptors on splenic macrophages. Hence, the circuit was dubbed the "cholinergic anti-inflammatory pathway". Subsequent work identified the α7 nicotinic ACh receptor (α7nAChR) as the crucial target for attenuation of pro-inflammatory cytokine release from macrophages and dendritic cells. Further investigation made the important discovery that cholinergic T cells within the spleen and not cholinergic nerve cells were the source of ACh that stimulated α7 receptors on splenic macrophages. Given the important role that inflammation plays in numerous disease processes, cholinergic anti-inflammatory mechanisms are under intensive investigation from a basic science perspective and in translational studies of animal models of diseases such as inflammatory bowel disease and rheumatoid arthritis. This basic work has already fostered several clinical trials examining the efficacy of VNS and cholinergic therapeutics in human inflammatory diseases. This review provides an overview of basic and translational aspects of the cholinergic anti-inflammatory response and relevant pharmacology of drugs acting at the α7nAChR.

NAMPT Is an Essential Regulator of RA-Mediated Periodontal Inflammation

Recent studies have indicated a potential correlation between rheumatoid arthritis (RA) and periodontal inflammation. We undertook this study to verify whether RA mediates periodontitis-like phenotypes in experimental mouse models of RA and to explore the role of nicotinamide phosphoribosyltransferase (NAMPT) in periodontal inflammation during RA pathogenesis. Periodontal inflammation and alveolar bone loss have been reported in mice with collagen-induced arthritis (CIA) and in genetically modified tumor necrosis factor–α (TNF-α) transgenic (TG) mouse models. Among the adipokines examined in our study, NAMPT expression was markedly upregulated in the periodontal ligament (PDL) tissues in RA mouse models and in human PDL cells stimulated by the proinflammatory cytokines, interleukin (IL) 1β and TNF-α. When NAMPT was overexpressed with the Nampt-synthesizing adenovirus vector (Ad- Nampt), the PDL cells exhibited an increased expression of cytokines (IL6), chemokines (IL8 and chemokine [C-C motif] ligand 5 [CCL5]), inflammatory mediators (cyclooxygenase 2 [COX-2]), and matrix-degrading enzymes (matrix metalloproteinase [MMP] 1 and MMP3). Inhibition of NAMPT by the intracellular NAMPT (iNAMPT) inhibitor, FK866, or by the sirtuin inhibitor, nicotinamide, in PDL cells led to inhibition of the IL1β or Ad- Nampt–induced upregulation of catabolic factors, whereas treatment with recombinant NAMPT protein or blockade of extracellular NAMPT (eNAMPT) with blocking antibody did not. Moreover, NAMPT inhibition by the intraperitoneal or intragingival injection of FK866 in CIA mice inhibited periodontal tissue damage, under conditions of RA. Thus, our results verified the co-occurrence of RA and periodontal inflammation using experimental mouse models of RA, suggesting that iNAMPT in PDL cells plays a pivotal role in the pathogenesis of RA-mediated periodontal inflammation by regulating the expression levels of catabolic genes, such as IL6, IL8, CCL5, COX-2, MMP1, and MMP3.

Anti-Arthritic Activity of Schistosoma mansoni and Trichinella spiralis Derived-Antigens in Adjuvant Arthritis in Rats: Role of FOXP3+ Treg Cells

A growing body of evidence supports the concept of helminths therapy in a variety of autoimmune diseases. Here, we aimed to investigate the protective effects of autoclaved Schistosoma mansoni antigen (ASMA) and Trichinella spiralis antigen (ATSA) on the clinical and immunopathological features of rheumatoid arthritis (RA). Adjuvant arthritis was induced by subcutaneous and intradermal injections of complete Freund’s adjuvant into the plantar surface of the right hind paw and the root of the tail, respectively. Rats were randomly assigned to serve as normal control, untreated arthritis, ASMA or ATSA-treated arthritis groups. Antigens were given by intradermal injection in two doses, two weeks apart. The development, progression of arthritic features, and the impact on animals’ gait and body weight were followed up for 4 weeks. The associated changes in serum cytokines (IL-17, IFN-γ and IL-10), joints’ histopathology and immunohistochemistry of Foxp3⁺ T regulatory cells (Tregs) were evaluated at the end of the study. Treatment with either ASMA or ATSA attenuated the progression of clinical features of polyarthritis, improved gait and body weight gain, reduced the elevated serum IL-17 and further increased both IFN-γ and IL-10. Histopathologically, this was associated with a remarkable regression of paws’ inflammation that was limited only to the subcutaneous tissue, and a significant increase in the number of Foxp 3+ cells versus the untreated arthritis group. In conclusion, both Schistosoma mansoni and Trichinella spiralis derived antigens exerted protective effect against adjuvant arthritis with better effect achieved by ASMA treatment. This anti-arthritic activity is attributed to upregulation of the Foxp3⁺ Tregs, with subsequent favorable modulation of both pro- and anti-inflammatory cytokines. The use of autoclaved parasitic antigens excludes the deleterious effects of imposing helminthic infection by using live parasites, which may pave the way to a new therapeutic modality in treating RA.

Suppression of collagen-induced arthritis with a serine proteinase inhibitor (serpin) derived from myxoma virus

Many viruses encode virulence factors to facilitate their own survival by modulating a host's inflammatory response. One of these factors, secreted from cells infected with myxoma virus, is the serine proteinase inhibitor (serpin) Serp-1. Because Serp-1 had demonstrated anti-inflammatory properties in arterial injury models and viral infections, it was cloned and evaluated for therapeutic efficacy in collagen-induced arthritis (CIA). Clinical severity was significantly lower in the Serp-1 protocols (p<0.0001) and blinded radiographs indicated that the Serp-1 group had significantly less erosions than the controls (p<0.01). Delayed-type hypersensitivity was lower in the Serp-1 group but antibody titers to type II collagen were not significantly altered. Recipients had minimal histopathologic synovial changes and did not develop neutralizing antibodies to Serp-1. These results indicate that Serp-1 impedes the pathogenesis of CIA and suggests that the therapeutic potential of serine proteinase inhibitors in inflammatory joint diseases, such as rheumatoid arthritis, should be investigated further.