Collagen induced arthritis as an experimental model for rheumatoid arthritis. Immunogenetics, pathogenesis and autoimmunity

An update of murine models and their methodologies in immune-mediated joint damage and pain research

Murine models have played an indispensable role in the understanding of rheumatic and musculoskeletal disorders (RMD), elucidating the genetic, endocrine and biomechanical pathways involved in joint pathology and associated pain. To date, the available models in RMD can be classified as induced or spontaneous, both incorporating transgenic alternatives that improve specific insights. It is worth noting that the selection of the most appropriate model together with the evaluation of their specific characteristics and technical capabilities are crucial when designing the experiments. Furthermore, it is also imperative to consistently adhere to the ethical standards concerning animal experimentation. Recognizing the inherent limitation that any model can entirely encapsulates the complexity of the pathophysiology of these conditions, the aim of this review is to provide an updated overview on the methodology of current murine models in major arthropathies and their immune-mediated pathways, addressing to basic, translational and pharmacological research in joint damage and pain.

Advancement in nanotechnology for treatment of rheumatoid arthritis: scope and potential applications

Rheumatoid arthritis is a hyperactive immune disorder that results in severe inflammation in synovial joints, cartilage, and bone deterioration, resulting in immobilization of joints. Traditional approaches for the treatment of rheumatoid arthritis are associated with some limiting factors such as suboptimal patient compliance, inability to control the progression of disorder, and safety concerns. Therefore, innovative drug delivery carriers for efficient therapeutic delivery at inflamed synovial sites with better safety assessment are urgently needed to address these issues. From this perspective, nanotechnology is an outstanding alternative to traditional drug delivery approaches, and it has shown great promise in developing novel carriers to treat rheumatoid arthritis. Considering the current research and future application of nanocarriers, it is believed that nanocarriers can be a crucial element in rheumatoid arthritis treatment. This paper covers all currently available pathophysiological aspects of rheumatoid arthritis and treatment options. Future research for the reduction of synovial inflammation should focus on developing multifunction nanoparticles capable of delivering therapeutic agents with improved safety, efficacy, and cost-effectiveness to be commercialized.

Sex differences in long-term effects of collagen-induced arthritis in middle-aged mice

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory disorder with high prevalence among middle-aged women. Collagen-induced arthritis (CIA) is the most widely used animal model of RA, however, sex differences and long-term effects of CIA in mice are poorly described in the literature. Aim: Therefore, the present study aimed to analyze the long-term effects of CIA on the joints of middle-aged mice of both sexes and to describe potential sex differences. Materials and methods: CIA was induced in middle-aged DBA/1J mice by immunization with bovine type II collagen and complete Freund's adjuvant. Saline was administered to control mice. Arthritis score assessment, plethysmometry, and thermal imaging of the joints were performed weekly for 15 weeks. Locomotor activity, micro-computed tomography, joint histology and biochemical analyses were performed at the end of the experiment. Results: Our results indicate a similar prevalence of arthritis in both sexes of mice-67% (8/12) of females and 89% (8/9) males with an earlier onset in males (day 14 vs. day 35). After the arthritis scores peaked on day 56 for males and day 63 for females, they steadily declined until the end of the experiment on day 105. A similar dynamics was observed in paw volume and temperature analyzing different aspects of joint inflammation. Long-term consequences including higher proteinuria (by 116%), loss of bone density (by 33.5%) and joint damage in terms of synovial hyperplasia as well as bone and cartilage erosions were more severe in CIA males compared to CIA females. There were no significant differences in locomotor activity between CIA mice and CTRL mice of any sex. Conclusion: This is the first study to describe the long-term effects of the CIA model in terms of sex differences in DBA/1J mice. Our results indicate sex differences in the dynamics, but not in the extent of arthritis. An earlier onset of arthritis and more severe consequences on joints, bones and kidneys were found in males. The underlying immune pathomechanisms responsible for the limited duration of the arthritis symptoms and the opposite sex difference in comparison to RA patients require further investigation.

Dopamine D2 receptor on CD4+ T cells is protective against inflammatory responses and signs in a mouse model of rheumatoid arthritis

BACKGROUND

Dopamine is a neurotransmitter and has been found to regulate lymphocytes by acting on dopamine receptors (DRs). CD4⁺ T cells express all the five subtypes of DRs, D1R to D5R. Although CD4⁺ T cells have been involved in pathogenesis of rheumatoid arthritis (RA), roles of DRs expressed on these cells in RA are poorly understood. This study determined whether D2R expressed on CD4⁺ T cells regulates inflammatory responses and signs in collagen type II (CII)-induced arthritis (CIA), a mouse model of RA.

METHODS

DBA/1 mice and C57BL/6 mice with global D1r or D2r deficiency (D1r^-/- or D2r^-/-) or CD4⁺ T cell-specific D2r deletion (D2r^fl/fl/CD4^Cre) were used to prepare CIA model by intradermal injection of CII. D2R agonist sumanirole was intraperitoneally administered in CIA mice. CD4⁺ T cells obtained from CIA mice were exposed to sumanirole or/and D2R antagonist L-741,626 in vitro. Arthritic symptoms were assessed by clinical arthritis scores. Flow cytometric assay measured frequencies of CD4⁺ T cell subsets (Th1, Th2, Th17 and Treg cells). Expression of specific transcription factors for the CD4⁺ T cell subsets was tested by Western blot. Cytokine production was estimated by quantitative PCR and ELISA.

RESULTS

CIA mice manifested a bias of CD4⁺ T cells towards Th1 and Th17 cells. D2r^-/- CIA mice showed a stronger bias towards Th1 and Th17 phenotypes than CIA mice, while D1r^-/- CIA mice did not show the changes. CD4⁺ T cell-specific D2r deletion exacerbated both the polarization towards Th1 and Th17 cells and the symptoms of arthritis. Sumanirole administration in CIA mice ameliorated the bias of CD4⁺ T cells towards Th1 and Th17 phenotypes as well as arthritic symptoms. Sumanirole treatment of in vitro CD4⁺ T cells obtained from CIA mice promoted the shift to Treg cells, and the effect of sumanirole was blocked by L-741,626.

CONCLUSIONS

D2R expressed on CD4⁺ T cells is protective against imbalance between pro-inflammatory and anti-inflammatory T cells and arthritic symptoms in CIA.

Clinical implications of tristetraprolin (TTP) modulation in the treatment of inflammatory diseases

Abnormal regulation of pro-inflammatory cytokine and chemokine mediators can contribute to the excess inflammation characteristic of many autoimmune diseases, such as rheumatoid arthritis, psoriasis, Crohn's disease, type 1 diabetes, and many others. The tristetraprolin (TTP) family consists of a small group of related RNA-binding proteins that bind to preferred AU-rich binding sites within the 3'-untranslated regions of specific mRNAs to promote mRNA deadenylation and decay. TTP deficient mice develop a severe systemic inflammatory syndrome consisting of arthritis, myeloid hyperplasia, dermatitis, autoimmunity and cachexia, due at least in part to the excess accumulation of proinflammatory chemokine and cytokine mRNAs and their encoded proteins. To investigate the possibility that increased TTP expression or activity might have a beneficial effect on inflammatory diseases, at least two mouse models have been developed that provide proof of principle that increasing TTP activity can promote the decay of pro-inflammatory and other relevant transcripts, and decrease the severity of mouse models of inflammatory disease. Animal studies of this type are summarized here, and we briefly review the prospects for harnessing these insights for the development of TTP-based anti-inflammatory treatments in humans.

Metabolomics reveals the intervention effect of Zhuang medicine Longzuantongbi granules on a collagen-induced arthritis rat model by using UPLC-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is known as "Fawang" in Zhuang medical theory. Longzuantongbi granules (LZTBG) is an in-hospital preparation used at the First Affiliated Hospital of the Guangxi University of Chinese Medicine. This medicine is based on traditional Zhuang medicine theory for the treatment of "Fawang", and has an effectiveness of over 86.67%. It comprises eight medicinal materials, including the main drug Toddalia asiatica (L.) Lam. and Kadsura coccinea (Lem.) A.C. Smith, the assisting drugs Alangium chinense (Lour.) Harms, Zanthoxylum nitidum (Roxb.) DC., Sinomenium acutum (Thunb.) Rehd.et Wils., Bauhinia championii (Benth.) Benth., Spatholobus suberectus Dunn, and Ficus hirta Vahl. All of these herbs are commonly used in Zhuang medicine.

AIM OF THE STUDY

This study aims to reveal the effect of LZTBG on collagen-induced arthritis (CIA) rats, to discover the potential efficacy-related biomarkers and explore the intervention mechanism of LZTBG from a molecular level, based on metabolomics.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were randomly assigned into a normal group, a CIA model group, a positive control (MTX) group and two different LZTBG treatment groups (5.4 g/kg/d and 2.7 g/kg/d). Body weight, arthritis index (AI), paw swelling, and hematoxylin and eosin (HE) staining experiments were used to evaluate the efficacy of the established model. A metabolomics method based on an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was established to analyze plasma taken from the rats, and to explore the interventional mechanism of LZTBG.

RESULTS

LZTBG showed a positive effect on the CIA model rats. Thirty-one differential metabolites were screened out, and combined with pathway analysis, 11 potential efficacy-related biomarkers were then mapped in the pathway. These included linoleic acid (LA), phosphatidylcholine (PC), lysophosphatidylcholine (LPC), arachidonic acid (AA), 12-HETE, alpha-linolenic acid (ALA), 13(S)-HOT, 2-oxobutanoate, 3-hydroxybutyric acid, L-Valine, and acetylcholine. Furthermore, it was found that these metabolites may exhibit an intervention effect by means of modulating pathways related to both lipid metabolism and amino acid metabolism to associated with inflammation.

CONCLUSION

LZTBG can effectively alleviate symptoms of RA, an effect that can primarily be attributed to the regulation of multiple pathways and multiple targets These results demonstrate that LC-MS/MS-based metabolomics is an advantageous technique for the investigation of the intervention effect and molecular mechanism of traditional compound medicine.

Angiotensin AT2 Receptor Stimulation Alleviates Collagen-Induced Arthritis by Upregulation of Regulatory T Cell Numbers

The angiotensin AT₂ receptor (AT₂R) is a main receptor of the protective arm of the renin-angiotensin system and exerts for instance anti-inflammatory effects. The impact of AT₂R stimulation on autoimmune diseases such as rheumatoid arthritis (RA) is not yet known. We investigated the therapeutic potential of AT₂R-stimulation with the selective non-peptide AT₂R agonist Compound 21 (C21) in collagen-induced arthritis (CIA), an animal model for inflammatory arthritis. Arthritis was induced by immunization of DBA/1J mice with collagen type II (CII). Prophylactic and therapeutic C21 treatment alleviates arthritis severity and incidence in CIA. Joint histology revealed significantly less infiltrates of IL-1 beta and IL-17A expressing cells and a well-preserved articular cartilage in C21- treated mice. In CIA, the number of CD4⁺CD25⁺FoxP3⁺ regulatory T (Treg) cells significantly increased upon C21 treatment compared to vehicle. T cell differentiation experiments demonstrated increased expression of FoxP3 mRNA, whereas IL-17A, STAT3 and IFN-gamma mRNA expression were reduced upon C21 treatment. In accordance with the mRNA data, C21 upregulated the percentage of CD4⁺FoxP3⁺ cells in Treg polarizing cultures compared to medium-treated controls, whereas the percentage of CD4⁺IL-17A⁺ and CD4⁺IFN-gamma⁺ T cells was suppressed. To conclude, C21 exerts beneficial effects on T cell-mediated experimental arthritis. We found that C21-induced AT₂R-stimulation promotes the expansion of CD4⁺ regulatory T cells and suppresses IL-17A production. Thus, AT₂R-stimulation may represent an attractive treatment strategy for arthritis.

Analysis of combined deficiency of interleukin-1 and -6 versus single deficiencies in TNF-mediated arthritis and systemic bone loss

Aims

Insufficient treatment response in rheumatoid arthritis (RA) patients requires novel treatment strategies to halt disease progression. The potential benefit of combination of cytokine-inhibitors in RA is still unclear and needs further investigation. To explore the impact of combined deficiency of two major cytokines, namely interleukin (IL)-1 and IL-6, in this study double deficient mice for IL-1αβ and IL-6 were investigated in different tumour necrosis factor (TNF)-driven inflammatory bone disorders, namely peripheral arthritis and sacroiliitis, as well as systemic bone loss.

Methods

Disease course, histopathological features of arthritis, and micro-CT (µCT) bone analysis of local and systemic bone loss were assessed in 15-week-old IL1^-/-IL6^-/-hTNFtg in comparison to IL1^-/-hTNFtg, IL6^-/-hTNFtg, and hTNFtg mice. µCT bone analysis of single deficient and wild-type mice was also performed.

Results

Combined deficiency of IL-1/IL-6 markedly ameliorated TNF-mediated arthritis and bilateral sacroiliitis, but without additive benefits compared to single IL-1 deficiency. This finding confirms the important role of IL-1 and the marginal role of IL-6 in TNF-driven pathways of local joint damage, but questions the efficacy of potential combinatorial therapies of IL-1 and IL-6 in treatment of RA. In contrast, combined deficiency of IL-1/IL-6 led to an additive protective effect on TNF-driven systemic bone loss compared to single IL-1 and IL-6 deficiency. This finding clearly indicates a common contribution of both IL-1 and IL-6 in TNF-driven systemic bone loss, and points to a discrepancy of cytokine dependency in local and systemic TNF-driven mechanisms of inflammatory arthritis.

Conclusion

Combinatorial treatments in RA might provide different benefits to inflammatory local arthritis and systemic comorbidities.

Cite this article: Bone Joint Res 2022;11(7):484–493.

Rheumatoid arthritis: Methods for two murine models

Rheumatoid arthritis is an incurable chronic inflammatory disease for which the pathophysiology is not fully understood, and treatment options are flawed. Thus, animal models are used to dissect disease pathogenesis and to develop improved therapeutics. However, accurately modeling all aspects of human rheumatoid arthritis in mice is not possible, and each model has pros and cons. Two useful murine models of rheumatoid arthritis are collagen induced arthritis and TNF induced arthritis. Both recapitulate the chronic inflammatory, erosive arthritis of human rheumatoid arthritis. Collagen induced arthritis has the added similarity to human rheumatoid arthritis of pathogenic autoantibodies, but can have variable degrees of arthritis severity, a challenge for experiments. In contrast, TNF induced arthritis tends to be uniform, but primarily models the innate arm of the immune response. Here we describe the benefits, limitations, and details for both models to help investigators select and implement an appropriate model to achieve the goals of their experiments.

Serum RANKL levels in Chinese patients with ankylosing spondylitis: a meta-analysis

Objective

We aimed to determine the association between serum receptor activator of nuclear factor-kappa B ligand (sRANKL) levels and ankylosing spondylitis (AS) in Chinese patients.

Methods

The PubMed, Cochrane Library, Embase, Chinese Biomedical Database, Web of Science, China National Knowledge Infrastructure, VIP, and Wan Fang databases were searched for studies conducted before October 1, 2020, without language restrictions. STATA version 12.0 and Revman version 5.3 were used to analyze the data. The standard mean differences (SMDs) and corresponding 95% confidence intervals (95% CIs) were calculated.

Results

Twelve clinical case–control studies, including 585 patients with AS and 423 healthy controls, were included. The combined SMD for sRANKL suggested that the sRANKL level was significantly higher in Chinese patients with AS than in healthy controls (SMD: 3.27, 95% CI 2.11–4.43, P < 0.00001). Serum RANKL-related factor osteoprotegerin (OPG) levels (SMD: 0.86, 95% CI 0.09–1.64, P < 0.03) were lower in the Chinese patients with AS than in healthy controls, and the RANKL/OPG ratio (SMD = 1.05, 95% CI 0.64–1.46, P < 0.00001) in Chinese patients with AS was approximately the same as that of healthy controls. Subgroup analysis indicated that patients from North and South China had higher sRANKL levels than controls; the sRANKL levels of patients from South China were higher in the subgroup with a Bath Ankylosing Spondylitis Functional Index (BASFI) of > 4 than those of patients in other subgroups. In terms of duration, patients with AS for > 8 years had higher sRANKL levels than health controls. Other subgroup analyses were conducted by region, language, source of control, age, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). In these subgroups, the sRANKL levels were significantly higher in the patients with AS than in healthy controls. The BASFI and BASDAI were sources of heterogeneity.

Conclusions

The sRANKL levels are higher in Chinese patients with AS, especially among those from South China. sRANKL levels may be positively correlated with the pathogenesis of AS among Chinese patients.

Origin and function of synovial macrophage subsets during inflammatory joint disease

Mononuclear phagocytes, including monocytes and macrophages, are a central component of the host's innate immune system designated to protect against invading pathogens. However, these cells do not only interact with various parts of the innate and adaptive immune system, but also fulfill indispensable duties during the control of tissue homeostasis and organ function. Moreover, macrophages are crucially involved in tissue remodeling and repair in response to damage. Simultaneously, mononuclear phagocytes might also contribute to the pathogenesis of various inflammatory and autoimmune diseases. In particular, their potential role in inflammatory joint diseases such as rheumatoid arthritis (RA) has drawn increasing attention and substantially shaped our general understanding of the role of monocytes and macrophages during health and disease. This review summarizes our current knowledge about the origin and function of mononuclear phagocytes within the joint and addresses their involvement in joint inflammation.

MiR-495 targeting dvl-2 represses the inflammatory response of ankylosing spondylitis

Ankylosing spondylitis (AS) is a type of rheumatic inflammatory disease. miRNAs participate in the process of regulating inflammatory response and bone differentiation. Herein, we aimed to test the effect of miR-495 on AS. The serum and tissues were obtained from traumatic fracture (health) and AS patients. The human fibroblast-like synovial (HFLS) cells were extracted from AS tissues. The contents of inflammatory factors and dishevelled 2 (DVL-2) were examined using enzyme-linked immunosorbent assay (ELISA). The ossification factors were detected by immunohistochemistry assay. Osteoclast was assessed by tartaric acid acid phosphatase (TRAP) assay. The cell viability and luciferase activity were measured using cell counting kit-8 (CCK-8) and dual-luciferase reporter system. The levels of factors were evaluated using quantitative real-time PCR (qRT-PCR) and western blotting. DVL-2 was a target gene for miR-495, according to the MicroRNA.org website and luciferase activity assay. The expressions of miR-495 and DVL-2 were negative corrected in AS. miR-495 and si-DVL-2 did not affect the cell viability. miR-495 and si-DVL-2 obviously inhibited inflammatory response by down-regulating tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 levels, and facilitated bone differentiation by up-regulating osteoprotegerin (OPG) and receptor activator for nuclear factor-κB ligand (RANKL) levels in HFLS cells. Besides, miR-495 and si-DVL-2 increased the expression of wnt3a, runt-related transcription factor 2 (RUNX-2) and β-catenin and reduced the phosphorylation of β-catenin. Collectively, miR-495 depressed inflammatory response and promoted bone differentiation of HFLS cells, and this was accompanied by mediating wnt/β-catenin/Runx-2 pathway by targeting DVL-2.

Analysis of Polymorphisms in the Mediator Complex Subunit 13-like (Med13L) Gene in the Context of Immune Function and Development of Experimental Arthritis

The Mediator complex subunit 13-like (MED13L) protein is part of the multi-protein mediator complex and plays an important role in gene transcription. Polymorphisms in the MED13L gene have been linked to congenital heart anomalies and intellectual disabilities. Despite recent evidence of indirect links of MED13L to cytokine release and inflammation, impact of genetic variations in MED13L on immune cells remains unexplored. The B10.RIII and RIIIS/J mouse strains vary in susceptibility to induced experimental autoimmune disease models. From sequencing data of the two mouse strains, we identified six polymorphisms in the coding regions of Med13L. Using congenic mice, we studied the effect of these polymorphisms on immune cell development and function along with susceptibility to collagen-induced arthritis, an animal model for rheumatoid arthritis. Combining in vivo disease data, in vitro functional data, and computational analysis of the reported non-synonymous polymorphisms, we report that genetic polymorphisms in Med13L do not affect the immune phenotype in these mice and are predicted to be non-disease associated.

Integrin, alpha9 subunit blockade suppresses collagen-induced arthritis with minimal systemic immunomodulation

Integrin, alpha9 subunit (hereinafter, alpha9) has been identified as a novel putative therapeutic target for rheumatoid arthritis (RA). Support for this target comes from the observations that alpha9 is overexpressed both in the joints of RA patients and in animal models of arthritis. In the experimental models, the increase in alpha9 expression precedes the onset of arthritic symptoms. The current study presents data on the pharmacological profile of an anti-alpha9 antibody in a collagen-induced arthritis (CIA) mouse model. Administration of an alpha9-blocking antibody in CIA mice suppressed the development of arthritis and significantly decreased plasma level of activated fibroblast-like synoviocyte (FLS)-derived biomarkers without reducing the formation of anti-type II collagen antibodies. While anti-alpha9 antibody administration significantly suppress the accumulation of immune cells in arthritic joints it had no effect on immune cell number in the spleen. Furthermore, in non-arthritic mice, alpha9 had no inhibitory effect in either a mixed lymphocyte reaction (MLR) or in a delayed type hypersensitivity (DTH) reaction. These results suggest that blocking alpha9 exerts its anti-arthritic effect through suppression of FLS-activation via a non-immune mediated mechanism. Finally, therapeutic administration of anti-alpha9 antibody alleviated established arthritis in CIA mice. Our data provide evidence that alpha9 blockade is a promising therapy for joint inflammation with minimal systemic immunomodulation.

The combination of FK506 and an anti-CD147 mAb exerts potential therapeutic effects on a mouse model of collagen-induced arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, and excessive T lymphocyte activation plays a critical role in the development of inflammation. CD147 is an antigen related to T cell activation, CD147 blockade exerts beneficial effects on RA. FK506, also known as tacrolimus, exerts strong immunosuppressive effects by inhibiting T cell activation. In this study, RL73 (an anti-mouse CD147 functional-grade purified antibody) and FK506 were co-administered to mice with collagen-induced arthritis (CIA). As expected, the combination of these two drugs produced superior therapeutic effects than either drug alone and enabled the administration of each drug at a lower dose. Moreover, joint damage and destruction were significantly improved in mice injected with both FK506 and RL73 compared with mice injected with either agent alone. These effects might have been observed because the proportions of CD4 + T and CD8 + T cells in the mouse spleen of the combination regimen were clearly decreased compared with each monotherapy. In addition, the proportions of Th2 subsets in the mouse spleen and peripheral blood were clearly increased, and the serum levels of the cytokines interleukin 4 (IL-4) and IL-10 were markedly increased in mice treated with the combination therapy compared with the other groups of mice. The splenic total number of T lymphocytes also showed that the inhibition of T lymphocytes was the most obvious in the combined treatment group. Based on the results from the present study, combining FK506 and the anti-CD147 mAb might be a new practical therapeutic option for the treatment of RA.

Metabolic fingerprinting of joint tissue of collagen-induced arthritis (CIA) rat: In vitro, high resolution NMR (nuclear magnetic resonance) spectroscopy based analysis

Rheumatoid arthritis (RA) is a systemic autoimmune disease whose major characteristics persistent joint inflammation that results in joint destruction and failure of the function. Collagen-induced arthritis (CIA) rat is an autoimmune disease model and in many ways shares features with RA. The CIA is associated with systemic manifestations, including alterations in the metabolism. Nuclear magnetic resonance (NMR) spectroscopy-based metabolomics has been successfully applied to the perchloric acid extract of the joint tissue of CIA rat and control rat for the analysis of aqueous metabolites. GPC (Glycerophosphocholine), carnitine, acetate, and creatinine were important discriminators of CIA rats as compared to control rats. Level of lactate (significance; p = 0.004), alanine (p = 0.025), BCA (Branched-chain amino acids) (p = 0.006) and creatinine (p = 0.023) was significantly higher in CIA rats as compared to control rats. Choline (p = 0.038) and GPC (p = 0.009) were significantly reduced in CIA rats as compared to control rats. Choline to GPC correlation was good and negative (Pearson correlation = -0.63) for CIA rats as well as for control rats (Pearson correlation = -0.79). All these analyses collectively considered as metabolic fingerprinting of the joint tissue of CIA rat as compared to control rat. The metabolic fingerprinting of joint tissue of CIA rats was different as compared to control rats. The metabolic fingerprinting reflects inflammatory disease activity in CIA rats with synovitis, demonstrating that underlying inflammatory process drives significant changes in metabolism that can be measured in the joint tissue. Therefore, the outcome of this study may be helpful for understanding the mechanism of metabolic processes in RA. This may be also helpful for the development of advanced diagnostic methods and therapy for RA.

Daily oral administration of low-dose methotrexate has greater antirheumatic effects in collagen-induced arthritis rats

Objectives

Methotrexate (MTX) is administered once or thrice weekly to patients with rheumatoid arthritis (RA). Even though RA continually progresses, MTX is not administered daily. Therefore, we investigated whether the daily administration of a low dose of MTX inhibits the progression of arthritis in collagen‐induced arthritis (CIA) rats.

Methods

Methotrexate was orally administered once weekly, thrice weekly and once daily to CIA rats, and arthritis scores were measured.

Key findings

When the same dose of MTX was administered, the exacerbation of arthritis was inhibited significantly more in the once‐daily group than in the other groups. When the dose in the once‐daily group was reduced to one‐fourth that of the current standard dosing method, arthritis scores were markedly lower in the once‐daily group than in the once and thrice‐weekly groups.

Conclusions

The daily administration of a low dose of MTX not only maintained normal levels that estimated adverse effects but also suppressed the progression of arthritis significantly more than the current standard dosing method. The results indicate that the reconsideration of dosing schedules based on the characteristics of MTX will lead to more effective RA therapy than that currently used in clinical practice.

Ossicular Bone Damage and Hearing Loss in Rheumatoid Arthritis: A Correlated Functional and High Resolution Morphometric Study in Collagen-Induced Arthritic Mice

Globally, a body of comparative case-control studies suggests that rheumatoid arthritis (RA) patients are more prone to developing hearing loss (HL). However, experimental evidence that supports this hypothesis is still lacking because the human auditory organ is not readily accessible. The aim of this study was to determine the association between bone damage to the ossicles of the middle ear and HL, using a widely accepted murine model of collagen-induced arthritis (RA mice). Diarthrodial joints in the middle ear were examined with microcomputer tomography (microCT), and hearing function was assessed by auditory brainstem response (ABR). RA mice exhibited significantly decreased hearing sensitivity compared to age-matched controls. Additionally, a significant narrowing of the incudostapedial joint space and an increase in the porosity of the stapes were observed. The absolute latencies of all ABR waves were prolonged, but mean interpeak latencies were not statistically different. The observed bone defects in the middle ear that were accompanied by changes in ABR responses were consistent with conductive HL. This combination suggests that conductive impairment is at least part of the etiology of RA-induced HL in a murine model. Whether the inner ear sustains bone erosion or other pathology, and whether the cochlear nerve sustains pathology await subsequent studies. Considering the fact that certain anti-inflammatories are ototoxic in high doses, monitoring RA patients’ auditory function is advisable as part of the effort to ensure their well-being.

MZ B cells migrate in a T-bet dependent manner and might contribute to the remission of collagen-induced arthritis by the secretion of IL-10

In mice, marginal zone (MZ) B cells are found principally in the MZ of the spleen and characterized as CD23-negative cells, primarily express polyreactive BCRs, high levels of complement receptor-2 and TLRs. Collagen-induced arthritis (CIA) is a commonly used animal model of human rheumatoid arthritis, considered as a Th1-mediated disease. Although the importance of MZ B cells in the initiation of CIA is well established, their role in remission is unexplored. Besides, playing a central role in Th1 cell development, T-box transcription factor (T-bet) has important functions in B cells. T-bet is regulated by IFN-γ and through the BCR and TLR9, the signals that have an impact on regulatory IL-10 production. In this work, we aimed to analyze the contribution of T-bet to the function of IL-10-positive MZ B cells. We demonstrate that during the remission phase of CIA, MZ B cells express an elevated level of T-bet and confirm the existence of IL-10/T-bet coexpressing cells. Moreover, we show that T-bet-expressing MZ B cells migrate toward CXCR3 ligand and secrete IL-10 by inflammatory stimuli. Our data suggest that T-bet might contribute to the remission of CIA by facilitating the regulatory potential of IL-10-positive MZ B cells.

Head-to-head comparison of protocol modifications for the generation of collagen-induced arthritis in a specific-pathogen free facility using DBA/1 mice

Collagen-induced arthritis (CIA) is a widely used mouse model for studying inflammatory arthritis (IA). However, CIA induction protocols differ between laboratories, and direct comparison between protocol variations has not been reported. To address this issue, DBA/1 mice housed in conventional and specific-pathogen free (SPF) facilities were administered various combinations of two doses of collagen type II (CII) in complete (CFA) or incomplete Freund's adjuvant (IFA); some mice were also injected with lipopolysaccharide (LPS) and/or additional CII at specific intervals. Mice were evaluated for IA over the subsequent 2 months. Depending directly on the combination of CII, CFA, IFA, and LPS used, the incidence of IA ranged between 20%-100%, and severity extended from mild to severe even in an SPF environment. Our results demonstrate for the first time in head-to-head comparisons that specific variations in the use of CII, CFA, IFA, and LPS can induce a range of arthritic disease intensity and severity in an SPF facility. Thus, distinct experimental settings can be designed for robust assessment of factors that either exacerbate or inhibit arthritis pathogenesis. Furthermore, by achieving 100% incidence in an SPF facility, the protocols provide a practical and humane benefit by reducing the number of mice necessary for experimental assessment.

Changes in Soluble CD18 in Murine Autoimmune Arthritis and Rheumatoid Arthritis Reflect Disease Establishment and Treatment Response

INTRODUCTION

In rheumatoid arthritis (RA) immune activation and presence of autoantibodies may precede clinical onset of disease, and joint destruction can progress despite remission. However, the underlying temporal changes of such immune system abnormalities in the inflammatory response during treat-to-target strategies remain poorly understood. We have previously reported low levels of the soluble form of CD18 (sCD18) in plasma from patients with chronic RA and spondyloarthritis. Here, we study the changes of sCD18 before and during treatment of early RA and following arthritis induction in murine models of rheumatoid arthritis.

METHODS

The level of sCD18 was analyzed with a time-resolved immunoflourometric assay in 1) plasma from early treatment naïve RA patients during a treat-to-target strategy (the OPERA cohort), 2) plasma from chronic RA patients, 3) serum from SKG and CIA mice following arthritis induction, and 4) supernatants from synovial fluid mononuclear cells (SFMCs) and peripheral blood mononuclear cells (PBMCs) from 6 RA patients cultured with TNFα or adalimumab.

RESULTS

Plasma levels of sCD18 were decreased in chronic RA patients compared with early RA patients and in early RA patients compared with healthy controls. After 12 months of treatment the levels in early RA patients were similar to healthy controls. This normalization of plasma sCD18 levels was more pronounced in patients with very early disease who achieved an early ACR response. Plasma sCD18 levels were associated with radiographic progression. Correspondingly, the serum level of sCD18 was decreased in SKG mice 6 weeks after arthritis induction compared with healthy littermates. The sCD18 levels in both SKG and CIA mice exhibited a biphasic course after arthritis induction with an initial increase above baseline followed by a decline. Shedding of CD18 from RA SFMC and RA PBMC cultures was increased by TNFα and decreased by adalimumab.

CONCLUSIONS

The plasma sCD18 levels were altered in patients with RA, in mice with autoimmune arthritis and in cell cultures treated with TNFα and adalimumab. Decreased levels of plasma sCD18 could reflect autoimmunity in transition from early to chronic disease and normalization in response to treatment could reflect autoimmunity in remission.

Old and new therapeutics for Rheumatoid Arthritis: in vivo models and drug development

Development of novel drugs for treatment of chronic inflammatory diseases is to a large extent dependent on the availability of good experimental in vivo models in order to perform preclinical tests of new drugs and for the identification of novel drug targets. Here, we review a number of existing rodent models for Rheumatoid Arthritis in the context of how these models have been utilized for developing established therapy in Rheumatoid Arthritis and, furthermore, the present use of animal models for studies of novel drug candidates. We have studied the literature in the field for the use of in vivo models during development of anti-rheumatic drugs; from Methotrexate to various antibody treatments, to novel drugs that are, or have recently been, in clinical trials. For novel drugs, we have explored websites for clinical trials. Although a single Rheumatoid Arthritis in vivo model cannot mirror the complexity of disease development, there exist a number of good animal models for Rheumatoid Arthritis, each defining some parts in disease development, which are useful for studies of drug response. We find that many of the established drugs were not tested in in vivo models before being used in the clinic, but rather animal models have been subsequently used to find mechanisms for efficacy. Finally, we report a number of novel drugs, tested in preclinical in vivo models, presently in clinical trials.

Experimental models of arthritis in which pathogenesis is dependent on TNF expression

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease characterized by joint damage as well as systemic manifestations. The exact cause of RA is not known. Both genetic and environmental factors are believed to contribute to the development of this disease. Increased expression of tumor necrosis factor (TNF) has been implicated in the pathogenesis of RA. Currently, the use of anti-TNF drugs is one of the most effective strategies for the treatment of RA, although therapeutic response is not observed in all patients. Furthermore, due to non-redundant protective functions of TNF, systemic anti-TNF therapy is often associated with unwanted side effects such as increased frequency of infectious diseases. Development of experimental models of arthritis in mice is necessary for studies on the mechanisms of pathogenesis of this disease and can be useful for comparative evaluation of various anti-TNF drugs. Here we provide an overview of the field and present our own data with two experimental models of autoimmune arthritis - collagen-induced arthritis and antibody-induced arthritis in C57Bl/6 and BALB/c mice, as well as in tnf-humanized mice generated on C57Bl/6 background. We show that TNF-deficient mice are resistant to the development of collagen-induced arthritis, and the use of anti-TNF therapy significantly reduces the disease symptoms. We also generated and evaluated a fluorescent detector of TNF overexpression in vivo. Overall, we have developed an experimental platform for studying the mechanisms of action of existing and newly developed anti-TNF drugs for the treatment of rheumatoid arthritis.

Anti-citrullinated-protein-antibody-specific intravenous immunoglobulin attenuates collagen-induced arthritis in mice

Administration of intravenous immunoglobulin (IVIg) is a recognized safe and efficient immunomodulation therapy for many autoimmune diseases. Anti-idiotypic antibody binding to pathogenic autoantibodies was proposed as one of the mechanisms attributed to the protective activity of IVIg in autoimmunity. The aim of this study was to fractionate the anti-anti-citrullinated protein anti-idiotypic-antibodies (anti-ACPA) from an IVIg preparation and to test it as a treatment for collagen-induced arthritis in mice. IVIg was loaded onto an ACPA column. The eluted fraction was defined as ACPA-specific-IVIg (ACPA-sIVIg). Collagen-induced-arthritis (CIA) was induced in mice. Mice were treated weekly with ACPA-sIVIg, low-dose-IVIg, high-dose-IVIg and phosphate-buffered saline (PBS). Sera-ACPA titres, anti-collagen anitbodies and cytokine levels were analysed by enzyme-linked immunosorbent assay (ELISA); antibody-forming-cell activity by enzyme-linked imunospot (ELISPOT) assay; and expansion of regulatory T cell (Treg ) population by fluorescence activated cell sorter (FACS). ACPA-sIVIg inhibited ACPA binding to citrullinated-peptides (CCP) in vitro 100 times more efficiently than the IVIg compound. ACPA-sIVIg was significantly more effective than the IVIg-preparation in attenuating the development of collagen-induced arthritis. Splenocytes from CIA mice treated with ACPA-sIVIg reduced the ACPA and anti-collagen-antibody titres, including the number of anti-collagen and ACPA antibody-forming cells. In parallel, splenocytes from ACPA-sIVIg treated mice secreted higher levels of anti-inflammatory cytokines and lower proinflammatory cytokines. The ACPA-sIVIg inhibitory potential was accompanied with expansion of the Treg population. Low-dose IVIg did not affect the humoral and cellular response in the CIA mice in comparison to the PBS-treated mice. Based on our results, IVIg may be considered as a safe compound for treating patients with rheumatoid arthritis by neutralizing pathogenic autoantibodies, reducing proinflammatory cytokines and expanding the Treg population.

Osteoarticular Expression of Musashi-1 in an Experimental Model of Arthritis

Background. Collagen-induced arthritis (CIA), a murine experimental disease model induced by immunization with type II collagen (CII), is used to evaluate novel therapeutic strategies for rheumatoid arthritis. Adult stem cell marker Musashi-1 (Msi1) plays an important role in regulating the maintenance and differentiation of stem/precursor cells. The objectives of this investigation were to perform a morphological study of the experimental CIA model, evaluate the effect of TNFα-blocker (etanercept) treatment, and determine the immunohistochemical expression of Msi1 protein. Methods. CIA was induced in 50 male DBA1/J mice for analyses of tissue and serum cytokine; clinical and morphological lesions in limbs; and immunohistochemical expression of Msi1. Results. Clinically, TNFα-blocker treatment attenuated CIA on day 32 after immunization (P < 0.001). Msi1 protein expression was significantly higher in joints damaged by CIA than in those with no lesions (P < 0.0001) and was related to the severity of the lesions (Spearman's rho = 0.775, P = 0.0001). Conclusions. Treatment with etanercept attenuates osteoarticular lesions in the murine CIA model. Osteoarticular expression of Msi1 protein is increased in joints with CIA-induced lesion and absent in nonlesioned joints, suggesting that this protein is expressed when the lesion is produced in order to favor tissue repair.

Animal models of rheumatoid arthritis: How informative are they?

Animal models of arthritis are widely used to de-convolute disease pathways and to identify novel drug targets and therapeutic approaches. However, the high attrition rates of drugs in Phase II/III rates means that a relatively small number of drugs reach the market, despite showing efficacy in pre-clinical models. There is also increasing awareness of the ethical issues surrounding the use of animal models of disease and it is timely, therefore, to review the relevance and translatability of animal models of arthritis. In this paper we review the most commonly used animal models in terms of their pathological similarities to human rheumatoid arthritis as well as their response to drug therapy. In general, the ability of animal models to predict efficacy of biologics in man has been good. However, the predictive power of animal models for small molecules has been variable, probably because of differences in the levels of target knockdown achievable in vivo.

Non-invasive in vivo imaging of arthritis in a collagen-induced murine model with phosphatidylserine-binding near-infrared (NIR) dye

Introduction

Development of non-invasive molecular imaging techniques that are based on cellular changes in inflammation has been of active interest for arthritis diagnosis. This technology will allow real-time detection of tissue damage and facilitate earlier treatment of the disease, thus representing an improvement over X-rays, which detect bone damage at the advanced stage. Tracing apoptosis, an event occurring in inflammation, has been a strategy used. PSVue 794 is a low-molecular-weight, near-infrared (NIR)-emitting complex of bis(zinc²⁺-dipicolylamine) (Zn-DPA) that binds to phosphatidylserine (PS), a plasma membrane anionic phospholipid that becomes flipped externally upon cell death by apoptosis. In this study, we evaluated the capacity of PSVue 794 to act as an in vivo probe for non-invasive molecular imaging assessment of rheumatoid arthritis (RA) via metabolic function in murine collagen-induced arthritis, a widely adopted animal model for RA.

Methods

Male DBA/1 strain mice were treated twice with chicken collagen type II in Freund’s adjuvant. Their arthritis development was determined by measuring footpad thickness and confirmed with X-ray analysis and histology. In vivo imaging was performed with the NIR dye and the LI-COR Odyssey Image System. The level of emission was compared among mice with different disease severity, non-arthritic mice and arthritic mice injected with a control dye without the Zn-DPA targeting moiety.

Results

Fluorescent emission correlated reliably with the degree of footpad swelling and the manifestation of arthritis. Ex vivo examination showed emission was from the joint. Specificity of binding was confirmed by the lack of emission when arthritic mice were given the control dye. Furthermore, the PS-binding protein annexin V displaced the NIR dye from binding, and the difference in emission was numerically measurable on a scale.

Conclusions

This report introduces an economical alternative method for assessing arthritis non-invasively in murine models. Inflammation in feet and ankles can be measured longitudinally using the PSVue 794 probe for cell death and with a commonly available multipurpose imager. This technique provides metabolic and functional information that anatomical measurement of footpad swelling or visual determination of arthritic index cannot. It also may decrease the number of animals required per experiment because tissue damage will not necessarily require evaluation by harvesting joints for histology.

CXCL13 antibody for the treatment of autoimmune disorders

BACKGROUND

Homeostatic B Cell-Attracting chemokine 1 (BCA-1) otherwise known as CXCL13 is constitutively expressed in secondary lymphoid organs by follicular dendritic cells (FDC) and macrophages. It is the only known ligand for the CXCR5 receptor, which is expressed on mature B cells, follicular helper T cells (Tfh), Th17 cells and regulatory T (Treg) cells. Aberrant expression of CXCL13 within ectopic germinal centers has been linked to the development of autoimmune disorders (e.g. Rheumatoid Arthritis, Multiple Sclerosis, Systemic Lupus Erythematosis). We, therefore, hypothesized that antibody-mediated disruption of the CXCL13 signaling pathway would interfere with the formation of ectopic lymphoid follicles in the target organs and inhibit autoimmune disease progression. This work describes pre-clinical development of human anti-CXCL13 antibody MAb 5261 and includes therapeutic efficacy data of its mouse counterpart in murine models of autoimmunity.

RESULTS

We developed a human IgG1 monoclonal antibody, MAb 5261 that specifically binds to human, rodent and primate CXCL13 with an affinity of approximately 5 nM and is capable of neutralizing the activity of CXCL13 from these various species in in vitro functional assays. For in vivo studies we have engineered a chimeric antibody to contain the same human heavy and light chain variable genes along with mouse constant regions. Treatment with this antibody led to a reduction in the number of germinal centers in mice immunized with 4-Hydroxy-3-nitrophenylacetyl hapten conjugated to Keyhole Limpet Hemocyanin (NP-KLH) and, in adoptive transfer studies, interfered with the trafficking of B cells to the B cell areas of mouse spleen. Furthermore, this mouse anti-CXCL13 antibody demonstrated efficacy in a mouse model of Rheumatoid arthritis (Collagen-Induced Arthritis (CIA)) and Th17-mediated murine model of Multiple Sclerosis (passively-induced Experimental Autoimmune Encephalomyelitis (EAE)).

CONCLUSIONS

We developed a novel therapeutic antibody targeting CXCL13-mediated signaling pathway for the treatment of autoimmune disorders.

Skewing dendritic cell differentiation towards a tolerogenic state for recovery of tolerance in rheumatoid arthritis

To date, the available options to treat autoimmune diseases such as rheumatoid arthritis (RA) include traditional corticoids and biological drugs, which are not exempt of adverse effects. The development of cellular therapies based on dendritic cells with tolerogenic functions (TolDCs) has opened a new possibility to efficiently eradicate symptoms and control the immune response in the field of autoimmunity. TolDCs are an attractive tool for antigen-specific immunotherapy to restore self-tolerance in RA and other autoimmune disorders. A promising strategy is to inject autologous self-antigen-loaded TolDCs, which are able to delete or reprogram autoreactive T cells. Different protocols for the generation of stable human TolDCs have been established and the therapeutic effect of TolDCs has been investigated in multiple rodent models of arthritis. Pilot studies in humans confirmed that TolDC application is safe, encouraging clinical trials using self-antigen-loaded TolDCs in RA patients. Although an abundance of molecular regulators of DC functions has been discovered in the last decade, no master regulator of tolerogenicity has been identified yet. Further research is required to define biomarkers or key regulators of tolerogenicity that might facilitate the induction and monitoring of TolDCs.

Collagen II antibody-induced arthritis in Tg1278TNFko mice: optimization of a novel model to assess treatments targeting human TNFα in rheumatoid arthritis

Background

Novel molecules that specifically target human TNFα in rheumatoid arthritis pose problems for preclinical assessment of efficacy. In this study collagen antibody-induced arthritis (CAIA) has been induced in human TNFα transgenic mice to provide a novel model that has been optimised for the evaluation of molecules targeting human TNFα.

Methods

Tg1278TNFko mice lack murine TNFα and are heterozygous for multiple copies of the human TNFα transgene that is expressed under normal physiological control. To establish CAIA, a collagen II monoclonal antibody cocktail (CAb) at 2, 4 or 8 mg was injected i.p. on Day 0 followed by a lipopolysaccharide (LPS) boost (10 or 100 μg) i.p. on Day 1 or Day 4. Animals were assessed for arthritis symptoms using a clinical score, cytokine levels (human TNFα, IL-1β and IL-6) in sera and joints, and histopathology. The dependence of the model on human TNFα was determined by dosing animals with etanercept.

Results

Tg1278TNFko animals treated with 2, 4 or 8 mg CAb on Day 0, with 100μg LPS on Day 4, had more severe arthritis and earlier symptoms than wild type animals at all doses of CAb tested. Subsequently it was found that the transgenic model did not require LPS at all for arthritis development but a lower dose of LPS (10 μg) was found necessary for reproducible and robust disease (close to 100% incidence, well-synchronised, with high arthritis scores). Furthermore the LPS challenge could be brought forward to Day 1 so that its’ actions to facilitate disease could be separated temporally from the arthritis phase (beginning about Day 4). Etanercept, administered immediately after the serum spike of cytokines associated with LPS had subsided, was able to dose-dependently inhibit arthritis development and this was associated with a marked protection of the joints histologically on Day 14. Etanercept was also able to reverse the signs of arthritis when given therapeutically allowing animals to be matched for disease burden before dosing begins.

Conclusions

The features of CAIA in Tg1278TNFko animals make the model well-suited to testing the next generation of therapeutics that will target human TNFα in rheumatoid arthritis.

Synthetic polymer as an adjuvant in collagen-induced arthritis

Collagen-induced arthritis (CIA), the classical animal model for experimental arthritis, resembles human rheumatoid arthritis in several aspects. However, the most widely used method of inducing CIA utilizes Freund's adjuvants, which can skew the elicited immune responses and also pose toxicity problems. This unit describes a new method of inducing CIA using a well defined stimuli-responsive synthetic polymer, poly-N-isopropylacrylamide-based adjuvant, mixed with the joint cartilage protein collagen type II (CII). PNiPAAm as an adjuvant is biodegradable and biocompatible, and does not skew immune responses. Thus, it is helpful in the development of arthritis models for studying antigen and tissue -specific autoimmune responses in an unbiased manner. This model is valuable for analyzing disease pathways, positional identification of genes regulating arthritis, validation of existing therapies, and exploring new therapeutic targets. Furthermore, this newly developed PNiPAAm adjuvant allows investigation of disease induction using specific autoantigens in several autoimmune diseases independently of toll-like receptors, as well as optimization of vaccine delivery systems for infectious diseases.

Attenuation of Collagen-Induced Arthritis in rat by nicotinic alpha7 receptor partial agonist GTS-21

This research was performed to observe the effect of GTS-21 on Collagen Induced Arthritis (CIA). CIA model was used and after the onset of arthritis, the rats were divided into three groups based on their clinical symptoms score. Two groups were intraperitoneally (IP) injected daily with GTS-21 (1 mg/kg, 2.5 mg/kg) for a week, whereas phosphate buffered saline (PBS) was used for the control group. Cytokine titers, radiological, and histological examinations were performed at different time points after treatment with GTS-21. Compared with those of the control, the levels of TNF-α, IL-1, and IL-6 in the serum were significantly reduced after GTS-21 management. In addition, radiological results show that bone degradation was inhibited as well. Moreover, the hematoxylin and eosin (H&E) staining indicated that the histological score was significantly alleviated in the therapeutic group. Tartrate-resistant acid phosphatase (TRAP) stain-positive cells were also detected in the destruction of the articular cartilage, which was significantly reduced compared with the control group. This study provides the first evidence on the effect of GTS-21 as a potential treatment for RA.

Pristane-induced lupus as a model of human lupus arthritis: evolvement of autoantibodies, internal organ and joint inflammation

OBJECTIVE

Arthritis is frequently seen in human lupus, but rarely in lupus models. Pristane-induced lupus (PIL) can be induced in various mouse strains such as BALB/c and C57BL/6. We herein characterize clinical and histological features of arthritis in the context of systemic lupus and provide a prudent comparison with models of rheumatoid arthritis (RA).

METHODS

A total of 57 BALB/c mice received pristane (PIL group) and were analyzed for serum autoantibodies (anti-chromatin-, -histone, -Sm, -dsDNA), as well as for clinical features and histopathology of joints, lungs and kidneys. Joint pathology was quantified by image analysis and tissue cytometry. Ten C57BL/6 mice (Bl/6-PIL) and historical groups of two different RA models were analyzed accordingly.

RESULTS

In BALB/c PIL, clinical arthritis started at three months, occurred finally in 79% of PIL (but not in controls, p<0.001) and correlated with areas of inflammation, erosion, cartilage damage, osteoclast numbers and total severity score (for all: r>0.7, p<0.001). After eight months, 58% of PIL (but no controls, p<0.001) had mild-erosive arthritis. In contrast to RA, the most frequent inflammatory cell type of the pannus was granulocytes (17.7%), PIL had lower numbers of osteoclasts, erosions rarely affected both layers of the cortical bone and there was no progression to complete joint destruction (even after one year of observation). Serum autoantibodies (auto-abs) preceded arthritis and became significantly elevated in all PIL; affected joints showed increased deposits of IgG (and IgM) within the inflammatory tissue, indicative of an ab-mediated process. PIL mice with arthritis also showed signs of pulmonary (100%) and renal (46%) lupus. In contrast to BALB/c, Bl/6-PIL mice did not develop any signs of arthritis.

CONCLUSION

PIL in BALB/c mice is characterized by severe organ involvement, typical autoabs and by a mild-erosive arthritis with similarities to, but also with distinct differences from, RA. PIL may help to study arthritis along with other key features of systemic lupus erythematosus after therapeutic interventions or in knock-out models based on a BALB/c but not on a C57BL/6 background.

Exploitation of the IDO Pathway in the Therapy of Rheumatoid Arthritis

Indoleamine 2,3-dioxygenase (IDO) is the first and rate-limiting step along the kynurenine pathway and is thought to play a key role in immune homeostasis through depletion of tryptophan and accumulation of kynurenines. In this review we summarize recent research into the possibility of harnessing the IDO pathway for the therapy of rheumatoid arthritis. Inhibition of IDO activity, or knockout of the gene encoding IDO, was shown to cause an increase in the severity of collagen-induced arthritis, an animal model of rheumatoid arthritis. The increased severity of disease was associated with elevated numbers of pathogenic Th1 and Th17 cells in the joints and draining lymph nodes. In another study, analysis of the kinetics of expression of downstream kynurenine pathway enzymes during the course of arthritis revealed a potential role for tryptophan metabolites in resolution of arthritis. Furthermore, the therapeutic administration of L-kynurenine or [3,4-dimethoxycinnamonyl]-anthranilic acid (a synthetic derivative of 3-hydroxy-anthranilic acid) significantly reduced both clinical and histological progression of experimental arthritis. These findings raise the possibility of exploiting the IDO pathway for the therapy of autoimmune disease.

Characterization of chemically defined poly-N-isopropylacrylamide based copolymeric adjuvants

PNiPAAm is a thermo-responsive polymer with an adjuvant activity. To identify the minimal chemical structure present within PNiPAAm responsible for its adjuvant property, three different constituent polymers with specific functional groups were synthesized through free radical reaction and tested their adjuvant potential along with PNiPAAm. Among them, polymer with isopropyl attached to an amide showed maximal adjuvant activity in rodents followed by polymer with amide or ketone functional groups. However, secondary amine containing polymer did not show any adjuvant activity. In addition, to improve the adjuvant properties of PNiPAAm, we incorporated an affinity ligand, boronate. At first, we synthesized and characterized the dual responsive copolymers PNiPAAm-co-VPBA and PNiPAAm-co-VPBA-co-DMAEMA. Biocompatibility of these copolymers was confirmed both in vitro and in vivo. Mice injected with these copolymers mixed with collagen (CII) developed significant levels of anti-CII antibodies comprising of all the major IgG subclasses and an increased T cell activation. At the injection site, massive infiltration of immune cells was observed. However, only PNiPAAm-co-VPBA-co-DMAEMA-CII induced arthritis in mice after injection of 0.5M fructose confirming the importance of effective release of CII from the polymer for its adjuvant activity. Thus, a fine balance of hydrophobicity and hydrophilicity promotes adjuvant properties and continuous release of antigen, in this case CII, from polymer is essential for its adjuvant activity.

Possible roles of IL-12-family cytokines in rheumatoid arthritis

The IL-12 family members, IL-12, IL-23, IL-27 and IL-35, are heterodimeric cytokines that share subunits and have important roles in autoimmunity. As well as their structural relationship the IL-12 family cytokines share some biological characteristics but have functional differences. These cytokines contribute to immune-mediated inflammation and our improved knowledge of their actions has led to alteration of the T(H)1-T(H)2 paradigm. In rheumatoid arthritis (RA), leukocyte migration, bone erosions and angiogenesis are modulated by an IL-23-IL-17 cascade, which can be negated in part by IL-12, IL-27 and IL-35 function. However, the IL-12 family members are a relatively new area of research and data have been generated mostly at the preclinical stage. Further studies in patients with RA are, therefore, required to determine whether these cytokines are valid targets for RA therapy.

Assessment of collagen-induced arthritis using cyanine 5.5 conjugated with hydrophobically modified glycol chitosan nanoparticles: correlation with 18F-fluorodeoxyglucose positron emission tomography data

OBJECTIVE

To evaluate the potential and correlation between near-infrared fluorescence (NIRF) imaging using cyanine 5.5 conjugated with hydrophobically modified glycol chitosan nanoparticles (HGC-Cy5.5) and (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) imaging of collagen-induced arthritis (CIA).

MATERIALS AND METHODS

We used 10 CIA and 3 normal mice. Nine days after the injecting collagen twice, microPET imaging was performed 40 minutes after the intravenous injection of 9.3 MBq (18)F-FDG in 200 µL PBS. One day later, NIRF imaging was performed two hours after the intravenous injection of HGC-cy5.5 (5 mg/kg). We assessed the correlation between these two modalities in the knees and ankles of CIA mice.

RESULTS

The mean standardized uptake values of (18)F-FDG for knees and ankles were 1.68 ± 0.76 and 0.79 ± 0.71, respectively, for CIA mice; and 0.57 ± 0.17 and 0.54 ± 0.20 respectively for control mice. From the NIRF images, the total photon counts per 30 mm(2) for knees and ankles were 2.32 ± 1.54 × 10(5) and 2.75 ± 1.51 × 10(5), respectively, for CIA mice, and 1.22 ± 0.27 × 10(5) and 0.88 ± 0.24 × 10(5), respectively, for control mice. These two modalities showed a moderate correlation for knees (r = 0.604, p = 0.005) and ankles (r = 0.464, p = 0.039). Moreover, both HGC-Cy5.5 (p = 0.002) and (18)F-FDG-PET (p = 0.005) imaging also showed statistically significant differences between CIA and normal mice.

CONCLUSION

NIRF imaging using HGC-Cy5.5 was moderately correlated with (18)F-FDG-PET imaging in the CIA model. As such, HGC-Cy5.5 imaging can be used for the early detection of rheumatoid arthritis.

Mapping pathogenesis of arthritis through small animal models

Animal models have been used for a number of decades to study arthritis and have contributed greatly to unravelling mechanisms of pathogenesis and validating new targets for treatment. All animal models have sets of limitations and over the years there has been natural refinement of existing models as well as creation of new ones. The success of genetic modification in mice has fuelled an exponential increase in the use of murine models for arthritis research and has significantly increased our understanding of disease processes. This review focuses on those rodent models of RA and OA that have current utility and are widely used by the research community. We highlight the subtle but important differences in existing models by positioning them on a pathogenesis map whereby model selection is determined by the specific aspect of disease to be studied. We discuss the evolving challenges in in vivo arthritis studies and our perceived gaps for future new model development. The document includes technical and cost implications of performing the described models, and the ethical considerations of such approaches.

Discovery of the macrocycle (9E)-15-(2-(pyrrolidin-1-yl)ethoxy)-7,12,25-trioxa-19,21,24-triaza-tetracyclo[18.3.1.1(2,5).1(14,18)]hexacosa-1(24),2,4,9,14(26),15,17,20,22-nonaene (SB1578), a potent inhibitor of janus kinase 2/fms-like tyrosine kinase-3 (JAK2/FLT3) for the treatment of rheumatoid arthritis

Herein, we describe the synthesis and SAR of a series of small molecule macrocycles that selectively inhibit JAK2 kinase within the JAK family and FLT3 kinase. Following a multiparameter optimization of a key aryl ring of the previously described SB1518 (pacritinib), the highly soluble 14l was selected as the optimal compound. Oral efficacy in the murine collagen-induced arthritis (CIA) model for rheumatoid arthritis (RA) supported 14l as a potential treatment for autoimmune diseases and inflammatory disorders such as psoriasis and RA. Compound 14l (SB1578) was progressed into development and is currently undergoing phase 1 clinical trials in healthy volunteers.

Dosing time-dependency of the arthritis-inhibiting effect of tacrolimus in mice

Stiffness and cytokine in blood levels show 24-h rhythms in rheumatoid arthritis (RA) patients. We previously revealed that higher therapeutic effects were obtained in RA patients and RA model animals when the dosing time of methotrexate was chosen according to the 24-h rhythms to cytokine. In this study, we examined whether a dosing time-dependency of the therapeutic effect of tacrolimus (TAC) could be detected in collagen-induced arthritis (CIA) and MRL/lpr mice. To measure the levels of cytokines and serum amyloid A (SAA), blood was collected from CIA mice at different times. TAC was administered at two different dosing times based on these findings and its effects on arthritis and toxicity were examined. Plasma tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), and SAA concentrations showed obvious 24-h rhythms with higher levels during the light phase and lower levels during the dark phase after RA crisis. The arthritis score and leukocyte counts were significantly lower in the group treated at 2 h after the light was turned on (HALO) than in the control and 14 HALO-treated groups. Our findings suggest that choosing an optimal dosing time could lead to the effective treatment of RA by TAC.

In vivo fluorescence imaging of E-selectin: quantitative detection of endothelial activation in a mouse model of arthritis

OBJECTIVE

In vivo optical imaging can delineate at the macroscopic level processes that are occurring at the cellular and molecular levels. E-selectin, a leukocyte adhesion molecule expressed on endothelium, is induced by tumor necrosis factor α (TNFα) and other cytokines involved in the pathogenesis of rheumatoid arthritis (RA). Collagen-induced arthritis (CIA) in mice is widely used to study the disease mechanisms and identify new treatments for RA. The purpose of this study was to demonstrate E-selectin-targeted fluorescence imaging in vivo in a mouse model of paw edema generated by local injection of TNFα as well as in mice with CIA.

METHODS

Animals with either CIA or TNFα-induced paw edema were injected with anti-E-selectin or control antibodies labeled with a DyLight 750-nm near-infrared (NIR) probe. In vivo imaging studies were undertaken using an NIR optical imaging system, and images were coregistered with plain radiographic images.

RESULTS

The mean fluorescence intensity measured over the time-course of TNFα-induced edema demonstrated a 1.97-fold increase (P<0.001) in signal in inflamed paws at 8 hours following injection of anti-E-selectin antibody, as compared to that in the isotype control. In the CIA model, a 2.34-fold increase in E-selectin-targeted signal was demonstrated (P<0.01). Furthermore, significant E-selectin-targeted signal was observed in the paws of animals immunized with collagen that did not display overt signs of arthritis.

CONCLUSION

E-selectin-targeted fluorescence in vivo imaging is a quantifiable method of detecting endothelial activation in arthritis and can potentially be applied to the quantification of disease and the investigation of the effects of new therapies. Importantly, this approach may also be useful for the detection of subclinical disease in RA.

Nonsteroidal anti-inflammatory drugs increase TNF production in rheumatoid synovial membrane cultures and whole blood

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase activity and hence PG production. However, the ability of NSAIDs to ameliorate pain and tenderness does not prevent disease progression in rheumatoid arthritis, a disease whose pathogenesis is linked to the presence of proinflammatory cytokines, such as TNF-alpha. To understand this observation, we have examined the effect of NSAIDs on the production of clinically validated proinflammatory cytokines. We show that a variety of NSAIDs superinduce production of TNF from human peripheral blood monocytes and rheumatoid synovial membrane cultures. A randomized, double-blinded, crossover, placebo-controlled trial in healthy human volunteers also revealed that the NSAID drug celecoxib increased LPS-induced TNF production in whole blood. NSAID-mediated increases in TNF are reversed by either the addition of exogenous PGE(2) or by a PGE(2) EP2 receptor agonist, revealing that PGE(2) signaling via its EP2 receptor provides a valuable mechanism for controlling excess TNF production. Thus, by reducing the level of PGE(2), NSAIDs can increase TNF production and may exacerbate the proinflammatory environment both within the rheumatoid arthritis joint and the systemic environment.

Therapeutic index of methotrexate depends on circadian cycling of tumour necrosis factor-α in collagen-induced arthritic rats and mice

Objectives

Rheumatoid arthritis is an autoimmune disorder of unknown aetiology. Morning stiffness, a characteristic feature of rheumatoid arthritis, shows a 24-h rhythm. Noticing this rhythm, we hypothesized the presence of a similar rhythm for a rheumatoid arthritis indicator, in addition to dosing-time dependency of the anti-rheumatic effect of methotrexate in arthritis induced by collagen in rats and mice, which reflect the symptomatology of rheumatoid arthritis patients.

Methods

To measure tumour necrosis factor (TNF)-α concentration, blood was taken at different times (2, 6, 10, 14, 18 or 22 h after the light was turned on (HALO)) in collagen-induced arthritic mice. Methotrexate was administered at two different dosing times based on these findings to estimate arthritis.

Key findings

The arthritis score was significantly lower in the 22 HALO-treated group than in the control and 10 HALO-treated groups in collagen-induced arthritic rats and mice. Plasma TNF-α concentrations showed obvious 24-h rhythms, with higher levels at light phase and lower levels at dark phase after rheumatoid arthritis crisis. Arthritis was relieved after administration of methotrexate during the dark phase in synchronization with the 24-h rhythm.

Conclusions

Our findings suggest that choosing an optimal dosing time associated with the 24-h cycling of TNF-α could lead to effective treatment of rheumatoid arthritis by methotrexate.

Proteasome inhibition as a novel therapy in treating rheumatoid arthritis

Rheumatoid arthritis (RA) is an erosive joint disease affecting about 1% of the population. The joint destruction is primarily mediated by special cells called fibroblast-like synoviocytes (FLS), which undergo an expansion forming a pannus that destroys the joint. Apoptosis has been rarely detected in the synovial lining. This has lead to the identification of pro-survival factors that are expressed in FLS at the sites of the pannus including mutant p53, hrd1, sentrin, and NF-kappaB. Current anti-inflammatory modalities only bring upon temporary relief and do not treat the pannus. Therefore, the FLS remain intact, joint destruction proceeds, patients relapse and eventually become resistant to all forms of therapy. To date, surgical removal of the pannus remains the only option to help delay further joint destruction. Therefore, we believe the future should hold a less invasive approach using a class of novel drugs called proteasome inhibitors to attenuate the growth of the FLS. We suggest the use of a novel proteasome inhibitor PS-341 to treat RA patients. PS-341 has been shown to induce apoptosis in many cancer cell lines and has lead to successful outcomes in phase II and III clinical trials of multiple myeloma. Moreover, PS-341 has been shown to sensitize a variety of cell lines to chemotherapeutic drugs, some of which are used as conventional therapy in RA. We hypothesize that PS-341 alone and/or in combination with conventional RA therapies could induce apoptosis in FLS in vitro and in vivo thereby treating the pannus. Prior to clinical use extensive research examining the effects of PS-341 in animal models of arthritis would be essential in order to understand the effects proteasome inhibition in disease biology. Overall, the purpose of our hypothesis is to suggest a realistic and alternative treatment for patients with refractory and non-refractory arthritic disease.

TNFalpha blockade in human diseases: mechanisms and future directions

Tumor necrosis factor-alpha (TNFalpha) antagonists have shown remarkable efficacy in a variety of immune-mediated inflammatory diseases (IMIDs). Therapeutic scope and limitations of these agents are reviewed in a recently published article in the Journal. In spite of their therapeutic popularity, little is known about their modes of action in vivo and factors that limit their scope of therapeutic use. Intriguingly, while all TNFalpha antagonists including blocking antibodies and soluble receptors are effective in certain IMIDs, only anti-TNFalpha antibodies are effective in other IMIDs. Early efforts at understanding how TNFalpha antagonists act in IMIDs centered on their ability to neutralize soluble TNFalpha or to block TNF receptors from binding to their ligands. Subsequent studies suggested a role of complement-mediated lysis or antibody-dependent cell cytotoxicity in their therapeutic effects. More recent models postulate that TNFalpha blockers may act by affecting intracellular signaling, with the end result being a hastened cell cycle arrest, apoptosis, suppression of cytokine production, or improved Treg cell function. TNFalpha antagonists can also modulate the functions of myofibroblasts and osteoclasts, which might explain how TNFalpha antagonists reduce tissue damage in chronic IMIDs. Focusing on the human therapeutic experience, this analytical review will review the biology of mechanisms of action, the limiting factors contributing to disease restriction in therapeutic efficacy, and the mechanism and frequency of treatment-limiting adverse responses of TNFalpha antagonists. It is hoped that the overview will address the needs of clinicians to decide on optimal use, spur clinical innovation, and incite translational researchers to set priorities for in vivo human investigations.

Key regulatory molecules of cartilage destruction in rheumatoid arthritis: an in vitro study

Background

Rheumatoid arthritis (RA) is a chronic, inflammatory and systemic autoimmune disease that leads to progressive cartilage destruction. Advances in the treatment of RA-related destruction of cartilage require profound insights into the molecular mechanisms involved in cartilage degradation. Until now, comprehensive data about the molecular RA-related dysfunction of chondrocytes have been limited. Hence, the objective of this study was to establish a standardized in vitro model to profile the key regulatory molecules of RA-related destruction of cartilage that are expressed by human chondrocytes.

Methods

Human chondrocytes were cultured three-dimensionally for 14 days in alginate beads and subsequently stimulated for 48 hours with supernatants from SV40 T-antigen immortalized human synovial fibroblasts (SF) derived from a normal donor (NDSF) and from a patient with RA (RASF), respectively. To identify RA-related factors released from SF, supernatants of RASF and NDSF were analyzed with antibody-based protein membrane arrays. Stimulated cartilage-like cultures were used for subsequent gene expression profiling with oligonucleotide microarrays. Affymetrix GeneChip Operating Software and Robust Multi-array Analysis (RMA) were used to identify differentially expressed genes. Expression of selected genes was verified by real-time RT-PCR.

Results

Antibody-based protein membrane arrays of synovial fibroblast supernatants identified RA-related soluble mediators (IL-6, CCL2, CXCL1–3, CXCL8) released from RASF. Genome-wide microarray analysis of RASF-stimulated chondrocytes disclosed a distinct expression profile related to cartilage destruction involving marker genes of inflammation (adenosine A2A receptor, cyclooxygenase-2), the NF-κB signaling pathway (toll-like receptor 2, spermine synthase, receptor-interacting serine-threonine kinase 2), cytokines/chemokines and receptors (CXCL1–3, CXCL8, CCL20, CXCR4, IL-1β, IL-6), cartilage degradation (matrix metalloproteinase (MMP)-10, MMP-12) and suppressed matrix synthesis (cartilage oligomeric matrix protein, chondroitin sulfate proteoglycan 2).

Conclusion

Differential transcriptome profiling of stimulated human chondrocytes revealed a disturbed catabolic–anabolic homeostasis of chondrocyte function and disclosed relevant pharmacological target genes of cartilage destruction. This study provides comprehensive insight into molecular regulatory processes induced in human chondrocytes during RA-related destruction of cartilage. The established model may serve as a human in vitro disease model of RA-related destruction of cartilage and may help to elucidate the molecular effects of anti-rheumatic drugs on human chondrocyte gene expression.

Collagen antibody-induced arthritis

Collagen antibody-induced arthritis (CAIA) is a simple mouse model of rheumatoid arthritis that can be used to address questions of pathogenic mechanisms and to screen candidate therapeutic agents. Arthritis is stimulated by the administration of a cocktail of monoclonal antibodies that are directed to conserved auto-antigenic epitopes in collagen type II, followed by endotoxin. The antibody-induced arthritis model offers several key advantages over the classic collagen-induced arthritis (CIA) model. These include rapid disease onset, high uptake rate, synchronicity, and the capacity to use genetically modified mice, such as transgenics and knockouts. This protocol takes 1-2 weeks to be completed.

Type II collagen autoimmunity in a mouse model of human rheumatoid arthritis

Type II collagen (CII) is expressed exclusively in the joint articular. Although the relationship between anti-CII immunity and human rheumatoid arthritis (RA) has been studied for a long time, definitive conclusions have not been reached. CII, as an autoantigen, has been studied extensively in small animal models, such as mice, and the collagen-induced arthritis (CIA) model has increased our understanding of the pathogenesis of human RA. In the present report, we summarize the available information on anti-CII immunity and discuss recent updates regarding pathogenesis in the CIA model, including the role of Th17 cells.

Pharmacokinetics and pharmacodynamics of DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)), a potent and selective inhibitor of tumor necrosis factor alpha-converting enzyme in rodents, dogs, chimpanzees, and humans

DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)) is a potent and selective inhibitor of tumor necrosis factor (TNF)-alpha-converting enzyme (TACE). It significantly inhibits lipopolysaccharide-induced soluble TNF-alpha production in blood from rodents, chimpanzee, and human, with IC(50) values ranging from 17 to 100 nM. In rodent models of endotoxemia, DPC 333 inhibited the production of TNF-alpha in a dose-dependent manner, with an oral ED(50) ranging from 1.1 to 6.1 mg/kg. Oral dosing of DPC 333 at 5.5 mg/kg daily for 2 weeks in a rat collagen antibody-induced arthritis model suppressed the maximal response by approximately 50%. DPC 333 was distributed widely to tissues including the synovium, the site of action for antiarthritic drugs. Pharmacokinetic and pharmacodynamic studies in chimpanzee revealed a systemic clearance of 0.4 l/h/kg, a V(ss) of 0.6 l/kg, an oral bioavailability of 17%, and an ex vivo IC(50) for the suppression of TNF-alpha production of 55 nM (n = 1). In a phase I clinical trial with male volunteers after single escalating doses of oral DPC 333, the terminal half-life was between 3 and 6 h and the ex vivo IC(50) for suppressing TNF-alpha production was 113 nM. Measurement of the suppression of TNF-alpha production ex vivo may serve as a good biomarker in evaluating the therapeutic efficacy of TACE inhibitors. Overall, the pharmacological profiles of DPC 333 support the notion that suppression of TNF-alpha with TACE inhibitors like DPC 333 may provide a novel approach in the treatment of various inflammatory diseases including rheumatoid arthritis, via control of excessive TNF-alpha production.