Rodent models of arthritis: relevance for human disease

Onosma bracteatum Wall Aqueous-Ethanolic Extract Suppresses Complete Freund's Adjuvant-Induced Arthritis in Rats via Regulation of TNF-α, IL-6, and C-Reactive Protein

Onosma bracteatum Wall (O. bracteatum) has been used traditionally for the management of arthritis; however, its therapeutic potential warrants further investigation. This study aimed to evaluate the anti-arthritic effects of the aqueous-ethanolic extract of O. bracteatum leaves (AeOB) in a rat model of complete Freund's adjuvant (CFA)-induced arthritis. Rats were treated with AeOB (250, 500, and 750 mg/kg), indomethacin (10 mg/kg), or a vehicle control from days 8 to 28 post-CFA injection. Arthritic score, paw diameter, and body weight were monitored at regular intervals. X-ray radiographs and histopathological analysis were performed to assess arthritic severity. Inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) were quantified by qPCR and icromatography. Phytochemical analysis of AeOB revealed alkaloids, flavonoids, phenols, tannins, Saponins, and glycosides. AeOB also exhibited antioxidant potential with an IC50 of 73.22 µg/mL in a DPPH assay. AeOB and diclofenac exhibited anti-inflammatory and anti-arthritic activities. Rats treated with AeOB at 750 mg/kg and indomethacin showed significantly reduced arthritic symptoms and joint inflammation versus the CFA control. The AeOB treatment downregulated TNF-α and IL-6 and decreased CRP levels compared with arthritic rats. Radiography and histopathology also showed improved prognosis. These findings demonstrate the anti-arthritic potential of AeOB leaves.

Expression of mBD4, mBD3 and CRAMP during type II collagen-induced arthritis/CIA and their association with inflammation and bone-remodeling markers

The aim of this study was to analyze the expression of mBD4, mBD3 and CRAMP in joint of mice with type II collagen-induced arthritis/CIA and to explore its possible association with IL-10, IL-4, IFN-γ, IL-17, MMP3, RANK/RANKL/OPG and histological parameters.

METHODS

CIA was induced in 44 DBA/1 J mice. The joints from mice were classified into the onset, peak and remission phase of CIA. Histological sections were stained with hematoxylin-eosin and safranin O. The expression of CRAMP, mBD-3, mBD-4, and MMP-3 was evaluated using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The expression of IL-10, IL-4, IFN-γ, IL-17, RANK/RANKL/OPG was analyzed by RT-PCR.

RESULTS

We observed that inflammation and immunostained cells for CRAMP increased in the peak and remission phases compared to the control group. In addition, increments in relative expressions of CRAMP were detected for the remission phase and in IL-4 and IL-17 in the peak phase compared to the control and onset phase. In addition, an increase in IL-10 in a peak phase compared to the control, as well as the relative expression of IFN-γ in remission phase was higher than in the onset phase. This was accompanied by an increase in cartilage damage in the peak phase compared to the control. Cells immunostained to MMP3 increased in the peak phase compared to the onset and control group, and relative expression of MMP3 was detected in the peak phase compared to the onset, remission, and control group. We observed that the relative expression of RANK and RANKL in the peak phase was higher than in control and onset phase. Finally, the relative expression of OPG in the peak phase compared to the onset, remission, and control group was detected. Regarding CRAMP behavior in the different phases studied, it was positively correlated with IL-4 and RANK, and showed a negative correlation with IFN-γ, IL-17, IL-10, RANKL, OPG and RANKL/OPG ratio in the control group. Also was positively correlated with IFN-γ, IL-17, IL-4, IL-10, as well as with RANK, RANKL, and OPG in the onset and peak phases of the CIA. In the peak phase, CRAMP showed a positive association with MMP3, and we observed a direct correlation between CRAMP and IFN-γ and RANKL/OPG ratio in remission phase. mBD3 correlates positively with IFN-γ, IL-17, IL-10, RANKL, OPG and RANKL/OPG ratio, and showed a negative correlation with CRAMP, MMP3, and RANK in the control group. Also, it was directly associated with IFN-γ, IL-17, IL-4, IL-10 and RANKL in the onset phase while it was inversely associated with CRAMP, MMP-3, RANK, RANKL, and OPG in the peak phase. Finally, mBD3 was inversely correlated with MMP3 in the remission phase and was directly associated with CRAMP, IFN-γ and RANKL/OPG ratio in this phase. mBD4 was directly associated with CRAMP, IFN-γ, IL-17, IL-4, IL-10, RANKL / OPG in the onset phase, and with CRAMP, IFN-γ, IL-17, IL-4, IL-10, MMP3, RANK, RANKL and OPG in the peak phase. Finally, mBD4 was positively associated with mBD3, IFN-γ, IL-17, IL-10, RANK, RANKL OPG and RANKL/OPG in the CIA remission phase.

CONCLUSIONS

Our results demonstrate that CRAMP plays an important role in CIA progress and suggest that its abundance is associated with local pro- and anti-inflammatory status. This makes us propose CRAMP as a possible contributor of bone reconstruction in the last stage of CIA.

Synthesis of N,N'-bis(1,5-dimethyl-2-phenyl-1,2-dihydro-3-oxopyrazol-4-yl) sebacamide that ameliorate osteoarthritis symptoms and improve bone marrow matrix structure and cartilage alterations induced by monoiodoacetate in the rat model: "Suggested potent anti-inflammatory agent against COVID-19"

To assess the chondroprotective effect and influence of N,N′-bis(1,5-dimethyl-2-phenyl-1,2-dihydro-3-oxopyrazol-4-yl) sebacamide (dpdo) that was synthesized through the reaction of phenazone with sebacoyl chloride and screened for its biological activity especially as anti-arthritic and anti-inflammatory agent in a monoiodoacetate (MA)-induced experimental osteoarthritis (OA) model. Thirty male albino rats weighing “190–200 g” were divided randomly into three groups (10 each): control, MA-induced OA, and MA-induced OA + dpdo. In MA-induced OA rat, the tumor necrosis factor alpha, interleukin 6, C-reactive protein, rheumatoid factors, reactive oxygen species, as well as all the mitochondrial markers such as mitochondria membrane potential, swelling mitochondria, cytochrome c oxidase (complex IV), and serum oxidative/antioxidant status (malondialdehyde level and activities of myeloperoxidase and xanthine oxidase) are elevated. Also, the activity of succinate dehydrogenase (complex II), levels of ATP, the level of glutathione (GSH), and thiol were markedly diminished in the MA-induced OA group compared to the normal control rats. These findings showed that mitochondrial function is associated with OA pathophysiological alterations and high gene expressions of (IL-6, TNF-a, and IL-1b) and suggests a promising use of dpdo as potential ameliorative agents in the animal model of OA and could act as anti-inflammatory agent in case of severe infection with COVID-19. It is clearly appeared in improving the bone cortex and bone marrow in the treated group with the novel compound in histological and transmission electron microscopic sections which is a very important issue today in fighting severe infections that have significant effects on the blood indices and declining of blood corpuscles like COVID-19, in addition to declining the genotoxicity and inflammation induced by MA in male rats. The novel synthesized compound was highly effective in improving all the above mentioned parameters.

Regulation of neutrophil pro-inflammatory functions sheds new light on the pathogenesis of rheumatoid arthritis

For more than two centuries now, rheumatoid arthritis (RA) is under investigation intending to discover successful treatment. Despite decades of scientific advances, RA is still representing a challenge for contemporary medicine. Current drug therapies allow to improve significantly the quality of life of RA patients; however, they are still insufficient to reverse tissue injury and are often generating side-effects. The difficulty arises from the considerable fluctuation of the clinical course of RA among patients, making the predictive prognosis difficult. More and more studies underline the profound influence of the neutrophil multifaceted functions in the pathogenesis of RA. This renewed interest in the complexity of neutrophil functions in RA offers new exciting opportunities for valuable therapeutic targets as well as for safe and well-tolerated RA treatments. In this review, we aim to update the recent findings on the multiple facets of neutrophils in RA, in particular their impact in promoting the RA-based inflammation through the release of the cytokine-like S100A8/A9 protein complex, as well as the importance of NETosis in the disease progression and development. Furthermore, we delve into the complex question of neutrophil heterogeneity and plasticity and discuss the emerging role of miRNAs and epigenetic markers influencing the inflammatory response of neutrophils in RA and how they could constitute the starting point for novel attractive targets in RA therapy.

Succinate receptor deficiency attenuates arthritis by reducing dendritic cell traffic and expansion of Th17 cells in the lymph nodes

Rheumatoid arthritis is a chronic inflammatory disease that leads to significant changes in metabolic activity. Succinate, an intermediate of the tricarboxylic acid cycle, has emerged as a metabolic mediator of the innate immune response. However, the involvement of succinate in the generation of the adaptive immune response and establishment of autoimmune response has not been addressed thus far. Here we demonstrated that the succinate-sensing receptor (Sucnr1/GPR91) plays a critical role in the development of immune-mediated arthritis. We found that Sucnr1 acts as a chemotactic gradient sensor that guides dendritic cells (DCs) into the lymph nodes, orchestrating the expansion of the T helper (Th)17-cell population and the development of experimental antigen-induced arthritis. Sucnr1-/- mice show reduced articular hyperalgesia, neutrophil infiltration and inflammatory cytokines in the joint, and reduced frequency of Th17 cells in draining lymph nodes. Adoptive transfer of wild-type (WT) DCs into Sucnr1-/- mice restored the development of arthritis. Moreover, DC-depleted mice transferred with Sucnr1-/- DCs developed less arthritis than mice transferred with WT DCs. In contrast, succinate given together with the immunization boosted the recruitment of DCs and the frequency of Th17 cells in draining lymph nodes, increasing arthritis severity. Therefore, the blockade of Sucnr1 may represent a novel therapeutic target of arthritis.-Saraiva, A. L., Veras, F. P., Peres, R. S., Talbot, J., de Lima, K. A., Luiz, J. P., Carballido, J. M., Cunha, T. M., Cunha, F. Q., Ryffel, B., Alves-Filho, J. C. Succinate receptor deficiency attenuates arthritis by reducing dendritic cell traffic and expansion of Th17 cells in the lymph nodes.

Effect of Trichilia monadelpha (Meliaceae) extracts on bone histomorphology in complete Freund's adjuvant-induced arthritis

AIM

This study aimed to assess the effect of petroleum ether extract (PEE), ethyl acetate extract (EthE), and ethanol extract (EAE) of Trichilia monadelpha stem bark on bone histomorphology in arthritis.

METHODS

Percentage inhibition of edema and arthritic scores in complete Freund's adjuvant-induced (0.1 ml of 5 mg/ml¹ of heat-killed Mycobacterium tuberculosis in paraffin oil-injected subplantar into the right hind paw) arthritic Sprague-Dawley rats treated with PEE, EthE, or EAE (10,30, and 100 mg/kg¹, respectively), dexamethasone (0.3-3.0 mg/kg¹), or methotrexate (0.1-1.0 mg/kg¹) over a 28-day period were estimated. Rat paws were radiographed and scored. Body weights were taken and paw tissues were harvested for histopathological studies.

RESULTS

The extracts significantly (P ≤ 0.01-0.0001) and dose dependently reduced the polyarthritic phase of arthritis. EAE and PEE significantly (P ≤ 0.01-0.0001) minimized edema spread from acute arthritic phase (days 0-10) to polyarthritic phase (days 10-28). EthE improved which deteriorated body weight in arthritis. All extracts significantly (P ≤ 0.05-0.01) improved arthritic score; reducing erythema, swelling and joint rigidity, and also significantly (P ≤ 0.05-0.01) reduced hyperplasia, pannus formation, and exudation of inflammatory cells into synovial spaces.

CONCLUSION

The stem bark extracts of T. monadelpha reduce bone tissue damage and resorption associated with adjuvant-induced arthritis, hence could be useful in managing arthritis in humans.

Adjuvant-induced mono-arthritis potentiates cerebral hemorrhage in the spontaneously hypertensive rats

AIMS

Patients with rheumatoid arthritis (RA), have a higher incidence of hypertension and stroke than the normal population. Currently there exists no animal model to study the pathogenic interactions of hemorrhagic stroke (HS) subsequent to chronic inflammation and hypertension. We have created and defined a hypertensive-mono-arthritic animal model who demonstrate gros signs of cerebral hemorrhage in presence of mono-arthritis.

MAIN METHODS

Spontaneously hypertensive rats (SHR) were fed either a high salt diet (4% NaCl; HSD) or Purina chow (RD) from weaning. Complete Freund's adjuvant (CFA) was injected into the left hind paw at 21-28weeks (control groups received saline (SAL)). Degree of inflammation, joint swelling, weight and blood pressure were monitored for 21days. Animals were then sacrificed and their brain and left hind paw evaluated.

KEY FINDINGS

All groups were hypertensive throughout the experimental period (>180mmHg systolic), irrespective of diet. Both CFA groups produced significant local inflammatory response in their injected paw with associated joint degradation and cellular infiltrates. Systemic plasma TNF-α levels were significantly elevated in CFA groups, with significant increase in TNF-α at 7 and 14days, compared to SAL groups. Cerebral hemorrhage was visualized in the CFA groups but not SAL controls, with a higher severity in HSD-CFA group.

SIGNIFICANCE

The mono-arthritic hypertensive animals are capable of developing HS upon induction of inflammatory insult. The HSD appears to exacerbate the inflammatory response and influence degree of the hemorrhage. Our novel, multi-disease model may provide an appropriate platform to study the pathogenesis of HS among arthritic patients.

HU-444, a Novel, Potent Anti-Inflammatory, Nonpsychotropic Cannabinoid

Cannabidiol (CBD) is a component of cannabis, which does not cause the typical marijuana-type effects, but has a high potential for use in several therapeutic areas. In contrast to Δ(9)-tetrahydrocannabinol (Δ(9)-THC), it binds very weakly to the CB1 and CB2 cannabinoid receptors. It has potent activity in both in vitro and in vivo anti-inflammatory assays. Thus, it lowers the formation of tumor necrosis factor (TNF)-α, a proinflammatory cytokine, and was found to be an oral antiarthritic therapeutic in murine collagen-induced arthritis in vivo. However, in acidic media, it can cyclize to the psychoactive Δ(9)-THC. We report the synthesis of a novel CBD derivative, HU-444, which cannot be converted by acid cyclization into a Δ(9)-THC-like compound. In vitro HU-444 had anti-inflammatory activity (decrease of reactive oxygen intermediates and inhibition of TNF-α production by macrophages); in vivo it led to suppression of production of TNF-α and amelioration of liver damage as well as lowering of mouse collagen-induced arthritis. HU-444 did not cause Δ(9)-THC-like effects in mice. We believe that HU-444 represents a potential novel drug for rheumatoid arthritis and other inflammatory diseases.

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.

Evaluation of anti-inflammatory activity of methanolic extract of leaves of Bougainvillea spectabilis in experimental animal models

BACKGROUND

Bougainvillea spectabilis (BS) (family Nyctaginaceae) is said to possess hypoglycemic and anti-inflammatory activities in experimental animals. We had set forward to examine the potential anti-inflammatory activities of BS in experimental models of inflammation.

MATERIALS AND METHODS

Fresh dried leaves from the flowering plant of BS were collected from the local area during the flowering season and air dried (215.00 g). Methanol was extracted, and the solvent was removed on a rotary evaporator under reduced pressure. The extract was freeze-dried (lyophilized) and the yield was 8 g. This was used as an emulsion prepared in propylene glycol and orally administered (20 and 50 mg/kg). Acute anti-inflammatory activity of BS was evaluated using carrageenan and dextran whereas chronic anti-inflammatory (immunoregulatory) activity was evaluated by Freund's adjuvant-induced arthritis model.

RESULTS

BS (20 mg/kg and 50 mg/kg) had shown significant anti-inflammatory effects 20.6% and 67.6%, respectively, on carrageenan-induced acute inflammatory models. In dextran-induced edema, the effect was 30% and 66%, respectively. The standard drug indomethacin (87.3% and 91.5%, respectively) showed better inhibitory response in both models. In arthritic model 50 mg/kg of BS showed significant chronic anti-inflammatory effect (38.46%) in comparison to the standard drug dexamethasone (84.6%).

CONCLUSION

Our data indicate that the methanol extract of BS (50 mg/kg) leaves has significant anti-inflammatory and immunoregulatory activity. Further studies involving isolation of active principles will help to pinpoint the mechanisms contributing to the observed activities of BS.

The role of glia in the spinal cord in neuropathic and inflammatory pain

Chronic pain, both inflammatory and neuropathic, is a debilitating condition in which the pain experience persists after the painful stimulus has resolved. The efficacy of current treatment strategies using opioids, NSAIDS and anticonvulsants is limited by the extensive side effects observed in patients, underlining the necessity for novel therapeutic targets. Preclinical models of chronic pain have recently provided evidence for a critical role played by glial cells in the mechanisms underlying the chronicity of pain, both at the site of damage in the periphery and in the dorsal horn of the spinal cord. Here microglia and astrocytes respond to the increased input from the periphery and change morphology, increase in number and release pro-nociceptive mediators such as ATP, cytokines and chemokines. These gliotransmitters can sensitise neurons by activation of their cognate receptors thereby contributing to central sensitization which is fundamental for the generation of allodynia, hyperalgesia and spontaneous pain.

Anti-Inflammatory Effect of Ebosin on Rat Collagen-Induced Arthritis through Suppressing Production of Interleukin-1β, Interleukin-6 and Tumor Necrosis Factor-α

Reumatoid arthritis (RA) is an autoimmune disease which has been studied experimentally using a wide variety of animal models including collagen-induced arthritis (CIA). Using this CIA model we studied the therapeutic effects and mechanism of action of Ebosin, a novel exopolysaccharide produced by Streptomyces sp. 139, on arthritis. Ebosin at 200, 400 and 600 mg/kg/day was orally administered to rats respectively between day 10 and 30 after immunization with chicken type II collagen. With the treatment arthritic progression was remarkably suppressed. Levels of anti-type II collagen-specific antibody, IL-1β and TNF-α were significantly lower in the Ebosin-treated CIA rats compared with the untreated controls. In cultured fibroblast-like synoviocytes (FLS), remarkable suppression of IL-1β, TNF-α and IL-6 production was detected at both protein and mRNA levels after Ebosin administration. Ebosin also resulted in lower activities of IL-1β-converting enzyme and TNF-α-converting enzyme in FLS. Based on these results, it is concluded that development and progression of rat CIA can be significantly suppressed by orally-administrated Ebosin. The therapeutic effect may be attributed to its inhibition in the production of IL-1β, TNF-α and IL-6 in the CIA rats.

Oral treatment with Hev b 13 prevents experimental arthritis in mice

Hev b 13 is an allergenic esterase obtained from the rubber tree Hevea brasiliensis, which has been shown recently to induce human monocytes to release interleukin (IL)-10 in vitro, and to exert a potent anti-inflammatory effect in vivo. Moreover, Hev b 13 has been shown to reduce clinical signs of inflammation and also histological damage to the distal colon of mice with 2,4,6-trinitrobenze sulphonic acid (TNBS)-induced colitis after its oral administration. The aim of this study was to investigate the effect of Hev b 13 on human mononuclear cells, as well as its therapeutic use in the methylated bovine serum albumin (mBSA) model of antigen-induced arthritis. Five days before the intra-articular challenge, and daily thereafter for 8 days, Hev b 13 was administered by oral gavage. In mice treated with a dose of 0·5 mg/kg of Hev b 13, the severity of oedema, leucocyte infiltration, pannus formation and cartilage erosion were reduced significantly. These findings underscore the anti-inflammatory activity suggested previously for Hev b 13, an activity speculated to be related to its interaction with monocytes/macrophages and the consequent stimulation of IL-10 release and reduction of tumour necrosis factor (TNF) release. The study also opens a wide range of possible applications in the field of immune-mediated inflammatory diseases.

Fatty acid amide hydrolase blockade attenuates the development of collagen-induced arthritis and related thermal hyperalgesia in mice

Fatty acid amide hydrolase (FAAH) is the primary degradative enzyme of the endocannabinoid anandamide (N-arachidonoylethanolamine), which activates cannabinoid CB(1) and CB(2) receptors. FAAH disruption reduces nociception in a variety of acute rodent models of inflammatory pain. The present study investigated whether these actions extend to the chronic, collagen-induced arthritis (CIA) model. We investigated the anti-arthritic and anti-hyperalgesic effects of genetic deletion or pharmacological inhibition of FAAH in the CIA model. FAAH (-/-) mice, and FAAH-NS mice that express FAAH exclusively in nervous tissue, displayed decreased severity of CIA and associated hyperalgesia. These phenotypic anti-arthritic effects were prevented by repeated daily injections of the CB(2) receptor antagonist, SR144528, but not the CB(1) receptor antagonist rimonabant. Similarly, repeated administration of the FAAH inhibitor URB597 reduced CIA severity, and acute administration of rimonabant, but not SR144528, blocked the anti-hyperalgesic effects of prolonged FAAH inhibition, suggesting that prolonged CB(2) receptor activation reduces the severity of CIA, whereas acute CB(1) receptor activation reduces CIA-induced hyperalgesia. In contrast, acute administration of URB597 elicited a CB(1) receptor-dependent anti-hyperalgesic effect. The observed anti-arthritic and anti-hyperalgesic properties of FAAH inhibition, coupled with a lack of apparent behavioral alterations, suggest that endocannabinoid modulating enzymes offer a promising therapeutic target for the development of novel pharmacological approaches to treat rheumatoid arthritis and associated hyperalgesia.

Helminth parasites and the modulation of joint inflammation

There is an urgent need to develop better therapeutics for autoimmune and autoinflammatory diseases, of which musculoskeletal disorders such as rheumatoid arthritis are particularly prevalent and debilitating. Helminth parasites are accomplished masters at modifying their hosts' immune activity, and so attention has focused on rodent-helminth model systems to uncover the workings of the mammalian immune response to metazoan parasites, with the hope of revealing molecules and/or mechanisms that can be translated into better treatments for human autoimmune and idiopathic disorders. Substantial proof-of-principal data supporting the concept that infection with helminth parasites can reduce the severity of concomitant disease has been amassed from models of mucosal inflammation. Indeed, infection with helminth parasites has been tried as a therapy in inflammatory bowel disease, and there are case reports relating to other conditions (e.g., autism); however, the impact of infection with parasitic helminths on musculoskeletal diseases has not been extensively studied. Here, we present the view that such a strategy should be applied to the amelioration of joint inflammation and review the literature that supports this contention.

Hydrodynamic delivery of chitosan-folate-DNA nanoparticles in rats with adjuvant-induced arthritis

50 kDa chitosan was conjugated with folate, a specific tissue-targeting ligand. Nanoparticles such as chitosan-DNA and folate-chitosan-DNA were prepared by coacervation process. The hydrodynamic intravenous injection of nanoparticles was performed in the right posterior paw in normal and arthritic rats. Our results demonstrated that the fluorescence intensity of DsRed detected was 5 to 12 times more in the right soleus muscle and in the right gastro muscle than other tissue sections. β-galactosidase gene expression with X-gal substrate and folate-chitosan-plasmid nanoparticles showed best coloration in the soleus muscle. Treated arthritic animals also showed a significant decrease in paw swelling and IL-1β and PGE₂ concentration in serum compared to untreated rats. This study demonstrated that a nonviral gene therapeutic approach using hydrodynamic delivery could help transfect more efficiently folate-chitosan-DNA nanoparticles in vitro/in vivo and could decrease inflammation in arthritic rats.

Nimesulide improves the disease modifying anti-rheumatic profile of methotrexate in mice with collagen-induced arthritis

Methotrexate is a disease modifying anti-rheumatic drug that is widely used for the treatment of rheumatoid arthritis. Nimesulide is a non-steroidal anti-inflammatory drug which is frequently used as adjuvant therapy for symptomatic alleviation of rheumatoid arthritis. In this study, we have evaluated the potential influence of nimesulide on the disease modifying anti-rheumatic properties of methotrexate using the collagen-induced arthritis model. Mice were immunized with collagen type II for the induction of arthritis and treated with methotrexate (2.5mg/kg) twice a week, nimesulide (20mg/kg) every other day or a combination of both drugs. Treatment started one week after the onset of arthritis until day 40. An arthritic index was used to compare the severity of arthritis between different treatments. In addition, articular hyperalgesia, joint stiffness, radiological deterioration and intra-articular leucocytic infiltration were evaluated. Methotrexate alone showed modest but significant analgesic and anti-inflammatory effects, and the effects of nimesulide were comparable. On the other hand, nimesulide significantly improved the disease modifying anti-rheumatic profile of methotrexate in terms of arthritic index and joint mobility. Furthermore, although nimesulide failed to show any radiological evidence of articular protection, it significantly improved methotrexate-induced joint protection as judged by X-ray analysis.

Protective effect of eotaxin-2 inhibition in adjuvant-induced arthritis

Eotaxin-2 is a potent chemoattractant for eosinophils, basophils and T helper type 2 (Th2) lymphocytes. The eotaxin-2/CCL24 receptor CCR3 is expressed in human brain, skin, endothelium and macrophages. The aim of the current study was to evaluate the protective effect of a monoclonal anti-eotaxin-2 antibody on the development of adjuvant-induced arthritis in rats (AIA). Adjuvant arthritis was induced in Lewis rats by intradermal injection of incomplete Freund's adjuvant +Mycobacterium tuberculosis. Rats were treated by intraperitoneal (i.p.) injection with three monoclonal antibodies against eotaxin-2 (G7, G8, D8) three times per week. Controls were treated with total mouse immunoglobulin G (IgG), methotrexate (MTX) or phosphate-buffered saline (PBS). Arthritis severity was evaluated by measuring ankle swelling, arthritic score, whole animal mobility and body weight. Sample joints were obtained for pathological evaluation and postmortem X-ray of ankle joints was performed to document erosions. Significant inhibition of arthritis was observed in rats treated with anti-eotaxin-2 antibodies compared to those treated with immunoglobulin or PBS. Inhibition was manifest in ankle diameter, arthritic score and mobility score. The antibody marked D8 showed the greatest efficacy. The effect was observed both in animals treated before the appearance of arthritis and in those where treatment was begun after development of joint inflammation. Combined treatment with D8 and MTX caused additional protection. Significant reduction of inflammation in D8-treated animals was also demonstrated in pathological and X-ray examinations. Inhibition of eotaxin-2 by monoclonal antibodies has a significant protective effect in adjuvant arthritis. These results may introduce a novel therapeutic target in rheumatoid arthritis and additional inflammatory joint disorders.

An ethanol extract of Piper betle Linn. mediates its anti-inflammatory activity via down-regulation of nitric oxide

The leaves of Piper betle (locally known as Paan) have long been in use in the Indian indigenous system of medicine for the relief of pain; however, the underlying molecular mechanisms of this effect have not been elucidated. The anti-inflammatory and immunomodulatory effects of an ethanolic extract of the leaves of P. betle (100 mg kg−1; PB) were demonstrated in a complete Freund's adjuvant-induced model of arthritis in rats with dexamethasone (0.1 mg kg−1) as the positive control. At non-toxic concentrations of PB (5–25 μg mL−1), a dose-dependent decrease in extracellular production of nitric oxide in murine peritoneal macrophages was measured by the Griess assay and corroborated by flow cytometry using the nitric oxide specific probe, 4,5-diaminofluorescein-2 diacetate. This decreased generation of reactive nitrogen species was mediated by PB progressively down-regulating transcription of inducible nitric oxide synthase in macrophages, and concomitantly causing a dose-dependent decrease in the expression of interleukin-12 p40, indicating the ability of PB to down-regulate T-helper 1 pro-inflammatory responses. Taken together, the anti-inflammatory and anti-arthrotic activity of PB is attributable to its ability to down-regulate the generation of reactive nitrogen species, thus meriting further pharmacological investigation.

Antiinflammatory glucocorticoid receptor ligand with reduced side effects exhibits an altered protein-protein interaction profile

Glucocorticoids are commonly used antiinflammatory agents whose use is limited by side effects. We have developed a series of glucocorticoid receptor (GR) ligands that retain the strong antiinflammatory activity of conventional glucocorticoids with reduced side effects. We present a compound, LGD5552, that binds the receptor efficiently and strongly represses inflammatory gene expression. LGD5552 bound to GR activates gene expression somewhat differently than glucocorticoids. It activates some genes with an efficacy similar to that of the glucocorticoids. However, other glucocorticoid-activated genes are not regulated by LGD5552. These differences may be because of the more efficient binding of corepressor in the presence of LGD5552, compared with glucocorticoid agonists. This class of nonsteroidal, GR-dependent antiinflammatory drugs may offer a safer alternative to steroidal glucocorticoids in the treatment of inflammatory disease.

Remission of collagen-induced arthritis is associated with high levels of transforming growth factor-beta expression in the joint

Immunization of genetically susceptible strains of mice with heterologous type II collagen leads to the induction of a self-limiting polyarthritis that begins to subside around 10 days after onset of clinical disease. The aims of this study were to compare pro- and anti-inflammatory cytokine expression in the joints during the course of arthritis in order to identify cytokines involved in spontaneous remission of arthritis. DBA/1 mice were immunized with type II collagen and an immunohistochemical analysis of expression of proinflammatory cytokines [tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6] and anti-inflammatory cytokines [IL-10, IL-1ra, transforming growth factor (TGF)-beta1, TGF-beta2 and TGF-beta3] in joints was carried out over the course of the disease. Both pro- and anti-inflammatory cytokines were found to be expressed in early arthritis. However, around 10 days after onset of arthritis, the level of expression of proinflammatory cytokines declined while the level of expression of anti-inflammatory cytokines, particularly TGF-beta1 and TGF-beta2, increased. Surprisingly, TNF-alpha continued to be expressed at low levels during the period of disease remission (30 days after onset). Blockade of TNF-alpha during the period of disease remission had no effect on TGF-beta expression. This study confirms that the level of inflammation in arthritis correlates strongly with the balance of pro- and anti-inflammatory cytokine expression in the joints. Of the anti-inflammatory cytokines studied, TGF-beta1 and TGF-beta2 predominate during the time of disease remission, suggesting that these cytokines are involved in regulating disease activity.

Analysing the effect of novel therapies on cytokine expression in experimental arthritis

Type II collagen-induced arthritis (CIA) is an animal model of rheumatoid arthritis that has been used extensively to address questions of disease pathogenesis and to validate novel therapeutic targets. Susceptibility to CIA is strongly associated with major histocompatibility complex class II genes, and the development of arthritis is accompanied by a robust T- and B-cell response to type II collagen. The main pathological features of CIA include proliferative synovitis with infiltration of inflammatory cells, pannus formation, cartilage degradation, erosion of bone and fibrosis. Pro-inflammatory cytokines, such as tumour necrosis factor alpha and interleukin-1beta, are expressed in the arthritic joints in both murine CIA and human rheumatoid arthritis, and blockade of these molecules results in amelioration of disease. Hence, there is a great deal of interest in the development of small-molecular-weight inhibitors of pro-inflammatory cytokines. There is also interest in the development and testing of drugs with the capacity to modulate the immune pathways involved in driving the inflammatory response in arthritis. For these reasons, there is a need to monitor the effect of novel treatments on cytokine expression in vivo. In this review, we outline the various techniques used to detect cytokines in experimental arthritis and describe how these techniques have been used to quantify changes in cytokine expression following therapeutic intervention.

Animal models of rheumatoid arthritis and their relevance to human disease

Rodent models of rheumatoid arthritis (RA) are useful tools to study the pathogenic process of RA. Among the most widely used models of RA are the streptococcal cell wall (SCW) arthritis model and the collagen-induced arthritis (CIA). Both innate and adaptive immune mechanisms are involved in these rodent models. While no models perfectly duplicate the condition of human RA, they are easily reproducible, well defined and have proven useful for development of new therapies for arthritis, as exemplified by cytokine blockade therapies. Besides SCW and CIA models, there are numerous others including transgenic models such as K/BxN, induced models such as adjuvant-induced and pristane models, and spontaneous models in certain mouse strains, that have been used to help understand some of the underlying mechanisms. This review provides an update and analysis of RA models in mice and rats. The array of models has provided rheumatologists and immunologists a means to understand the multifactorial disease in humans, to identify new drug targets, and to test new therapies.

A novel synthetic, nonpsychoactive cannabinoid acid (HU-320) with antiinflammatory properties in murine collagen-induced arthritis

OBJECTIVE

To explore the antiarthritic potential of a novel synthetic cannabinoid acid, Hebrew University-320 (HU-320), in the DBA/1 mouse model of arthritis, and to investigate in vitro antiinflammatory and immunosuppressive effects of HU-320 on macrophages and lymphocytes.

METHODS

DBA/1 mice were immunized with bovine type II collagen (CII) to induce arthritis and then injected intraperitoneally daily with HU-320. The effects of treatment on arthritic changes in hind feet were assessed clinically and histologically, and draining lymph node responses to CII were assayed. Murine splenic and human blood lymphocytes were cultured to study the effect of HU-320 on polyclonal mitogenic stimulation. Macrophage cultures were set up to evaluate in vitro effects of HU-320 on production of tumor necrosis factor alpha (TNF alpha) and reactive oxygen intermediates (ROIs). The effect of HU-320 administration on lipopolysaccharide-induced serum TNF levels was assayed using C57BL/6 mice. Bioactive TNF production was measured using BALB/c clone 7 target cells. Evaluation of HU-320 psychoactivity was performed using established laboratory tests on Sabra mice.

RESULTS

Systemic daily administration of 1 and 2 mg/kg HU-320 ameliorated established CII-induced arthritis. Hind foot joints of treated mice were protected from pathologic damage. CII-specific and polyclonal responses of murine and human lymphocytes were down-modulated. HU-320 inhibited production of TNF from mouse macrophages and of ROIs from RAW 264.7 cells and suppressed the rise in serum TNF level following endotoxin challenge. HU-320 administration yielded no adverse psychotropic effects in mice.

CONCLUSION

Our studies show that the novel synthetic cannabinoid acid HU-320 has strong antiinflammatory and immunosuppressive properties while demonstrating no psychoactive effects. The profound suppressive effects on cellular immune responses and on the production of proinflammatory mediators all indicate its usefulness as a novel nonpsychoactive, synthetic antiinflammatory product.

Heterogeneous requirement of IkappaB kinase 2 for inflammatory cytokine and matrix metalloproteinase production in rheumatoid arthritis: implications for therapy

OBJECTIVE

To investigate the potential role of IkappaB kinase 1 (IKK-1) and IKK-2 in the regulation of nuclear factor kappaB (NF-kappaB) activation and the expression of tumor necrosis factor alpha (TNFalpha), as well as interleukin-1beta (IL-1beta), IL-6, IL-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMPs), in rheumatoid arthritis (RA).

METHODS

Recombinant adenoviruses expressing beta-galactosidase, dominant-negative IKK-1 and IKK-2, or IkappaBalpha were used to infect ex vivo RA synovial membrane cultures and synovial fibroblasts obtained from patients with RA undergoing joint replacement surgery, or human dermal fibroblasts, human umbilical vein endothelial cells (HUVECs), and monocyte-derived macrophages from healthy volunteers. Then, their effect on the spontaneous or stimulus-induced release of inflammatory cytokines, VEGF, and MMPs from RA synovial membrane cells was examined.

RESULTS

IKK-2 was not required for lipopolysaccharide (LPS)-induced NF-kappaB activation or TNFalpha, IL-6, or IL-8 production in macrophages, but was essential for this process in response to CD40 ligand, TNFalpha, and IL-1. In synovial fibroblasts, dermal fibroblasts, and HUVECs, IKK-2 was also required for LPS-induced NF-kappaB activation and IL-6 or IL-8 production. In RA synovial membrane cells, IKK-2 inhibition had no effect on spontaneous TNFalpha production but significantly reduced IL-1beta, IL-6, IL-8, VEGF, and MMPs 1, 2, 3, and 13.

CONCLUSION

Our study demonstrates that IKK-2 is not essential for TNFalpha production in RA. However, because IKK-2 regulates the expression of other inflammatory cytokines (IL-1beta, IL-6, and IL-8), VEGF, and MMPs 1, 2, 3, and 13, which are involved in the inflammatory, angiogenic, and destructive processes in the RA joint, it may still be a good therapeutic target.

Inhibition of adjuvant-induced arthritis by systemic tissue inhibitor of metalloproteinases 4 gene delivery

OBJECTIVE

An imbalance in the matrix metalloproteinase:tissue inhibitor of metalloproteinases (MMP:TIMP) ratio in favor of MMP appears to be an important determinant of tissue damage in arthritis. We undertook this study to explore whether reversal of this imbalance in favor of TIMP would alter this process and to examine the mechanism of this alteration.

METHODS

We administered human TIMP-4 by electroporation-mediated intramuscular injection of naked DNA using the rat adjuvant-induced arthritis (AIA) model.

RESULTS

Intramuscular naked TIMP-4 gene administration resulted in high circulating TIMP-4 levels and completely abolished arthritis development in the rat AIA model. This inhibition was associated with significantly decreased MMP activity in the joint tissue as well as with significantly decreased serum and tissue tumor necrosis factor alpha levels and serum interleukin-1alpha levels compared with animals with arthritis. The mutation of cysteine at position 1 of TIMP-4 failed to block the development of AIA.

CONCLUSION

Our data indicate that TIMP-4 is a potent antiinflammatory agent, and that its antiarthritis function may be mediated by MMPs. Arthritis-inhibiting effects of TIMP-4 may suggest a unique application of this gene therapy method for arthritis.

Immunization of rats with homologous type XI collagen leads to chronic and relapsing arthritis with different genetics and joint pathology than arthritis induced with homologous type II collagen

The most commonly used animal model for rheumatoid arthritis (RA) is collagen-induced arthritis (CIA), induced by immunization with type II collagen (CII), a cartilage restricted protein. In this work we show that type XI collagen (CXI), which is a minor component in cartilage, induces a different form of erosive and chronic relapsing polyarthritis in rats. Using a series of inbred rat strains involving various genetic backgrounds (DA, LEW, E3), and congenic MHC regions (a, u, f, n, c, d), we found that CXI induced arthritis (C(XI)IA) is associated with the RT1f haplotype in contrast to CII induced arthritis (C(II)IA), which is associated with the RT1a and RT1u haplotypes. The C(XI)IA follows a chronic disease course affecting peripheral joints with both progression and relapses, which appear not to cease (occurring >800 days). Susceptible strains showed a sustained antibody response to CXI with time indicating that the autoimmune response was self-perpetuated. Microscopic analysis of the joints at different stages demonstrated the severe destruction of bone and cartilage by pannus tissue consisting of activated macrophages and T cells. The main difference to joints from rats with C(II)IA was larger numbers of infiltrating lymphocytes and these tended to form follicle-like aggregates. Surprisingly, males were more susceptible to C(XI)IA than females whereas the opposite has been observed in other rat arthritis models, including C(II)IA. Taken together, C(XI)IA is a chronic relapsing and erosive polyarthritis that is MHC associated, which in fact fulfills the criteria for diagnosis of RA. Thus the C(XI)IA model will be useful as a novel and relevant animal model for RA.

Chronic relapsing homologous collagen-induced arthritis in DBA/1 mice as a model for testing disease-modifying and remission-inducing therapies

OBJECTIVE

To test whether the chronic relapsing arthritis induced by immunizing DBA/1 mice with homologous type II collagen is a valuable model for testing disease-modifying antiarthritic drugs.

METHODS

Six-week-old male DBA/1 mice were immunized with murine type II collagen in Freund's complete adjuvant, resulting in a chronic relapsing polyarthritis in >80% of the mice 4 weeks after immunization. At the onset of clinical arthritis, mice were treated for 4 weeks with different treatments, including anti-tumor necrosis factor (anti-TNF) and antiinterleukin-12 (anti-IL-12) antibodies, salbutamol, or indomethacin. Alternatively, treatment was administered as a pulse at the beginning of clinical arthritis. Pulse treatments tested included anti-CD3 in combination with anti-TNF, anti-TNF alone, and anti-CD4, either alone or in combination with anti-TNF. After 4 weeks of arthritis, mice were killed and hind paws were assessed histologically for joint damage.

RESULTS

Anti-TNF and salbutamol both suppressed clinical arthritis more effectively than indomethacin and, moreover, protected the joints from damage, whereas indomethacin did not. Anti-IL-12 treatment initiated after the onset of clinical symptoms accelerated disease. Pulse therapy with anti-CD3 plus anti-TNF was found to induce remission, clinically as well as histologically, whereas a pulse with either anti-CD4, anti-TNF, or the combination of anti-CD4 plus anti-TNF was less effective.

CONCLUSION

Chronic relapsing homologous collagen-induced arthritis is a valuable model for identifying remission-inducing antiarthritic drugs and has predictive value with respect to their joint-protective potency.

Therapeutic efficacy of a novel membrane-targeted complement regulator in antigen-induced arthritis in the rat

OBJECTIVE

Complement system activation is strongly implicated as a factor in the pathogenesis of chronic synovitis in human rheumatoid arthritis. The objective of this study was to explore the therapeutic potential and local retention of a novel membrane-targeting complement regulatory protein, derived from human complement receptor 1, in the experimental setting of rat antigen-induced arthritis.

METHODS

Sensitized animals were treated at the time of arthritis induction with a single intraarticular (IA) dose of the membrane-targeting regulator APT070, a non-membrane-targeting control regulator (APT898), or vehicle control, and disease was assessed clinically and histologically. In addition, immunocytochemical analysis was performed on sections from normal rat knee joints at various time points after IA injection with APT070.

RESULTS

Animals treated with APT070 showed a dose-dependent therapeutic effect, with significantly milder clinical and histologic disease compared with both other treatment groups (P < 0.008 at the higher dose) and minimal evidence of erosive disease at study end in the active treatment group. Immunoperoxidase and immunofluorescence studies demonstrated local retention of APT070 on cell surface membranes within the normal joint up to 48 hours after IA injection.

CONCLUSION

These results show that IA complement inhibition represents an effective therapeutic strategy in experimental arthritis, by demonstrating that the exogenous delivery of a membrane-targeting complement regulator can result in prolonged synovial cell surface binding and significant clinical benefit in vivo. Complement inhibitory strategies of this type should be considered as novel therapies in human inflammatory arthritis.