Apoptosis and p53 expression in rat adjuvant arthritis

Bioactive compounds and therapeutic role of Brassica oleracea L. seeds in rheumatoid arthritis rats via regulating inflammatory signalling pathways and antagonizing interleukin-1 receptor action

CONTEXT

Rheumatoid arthritis (RA) is a chronic, progressive autoimmune disease characterized by aggressive and systematic polyarthritis.

OBJECTIVE

The present study aimed to isolate and identify the phenolic constituents in Brassica oleracea L. (Brassicaceae) seeds methanolic extract and evaluates its effect against rheumatoid arthritis in rats referring to the new therapy; interleukin-1 receptor antagonist (IL-1RA).

MATERIALS AND METHODS

The GC/MS profiling of the plant was determined. Arthritis induction was done using complete Freund's adjuvant. Arthritis severity was assessed by percentage of edema and arthritis index. IL-1 receptor type I gene expression, interleukin-1β (IL-1β), oxidative stress markers, protein content, inflammatory mediators, prostaglandin-E2 (PGE2), genetic abnormalities and the histopathological features of ankle joint were evaluated.

RESULTS

For the first time twelve phenolic compounds had been isolated from the seeds extract. Treatment with extract and IL-1RA improved the tested parameters by variable degrees.

CONCLUSIONS

RA is an irreversible disease, where its severity increases with the time of induction. Brassica oleracea L. seeds extract is considered as a promising anti-arthritis agent. IL-1 RA may be considered as an unusual therapeutic agent for RA disease. More studies are needed to consider the seeds extract as a nutraceutical agent and to recommend IL-1RA as a new RA drug.

Anti-arthritic effect of chicken embryo tissue hydrolyzate against adjuvant arthritis in rats (X-ray microtomographic and histopathological analysis)

Finding new, safe strategies to prevent and control rheumatoid arthritis is an urgent task. Bioactive peptides and peptide-rich protein hydrolyzate represent a new trend in the development of functional foods and nutraceuticals. The resulting tissue hydrolyzate of the chicken embryo (CETH) has been evaluated for acute toxicity and tested against chronic arthritis induced by Freund's full adjuvant (modified Mycobacterium butyricum) in rats. The antiarthritic effect of CETH was studied on the 28th day of the experiment after 2 weeks of oral administration of CETH at doses of 60 and 120 mg/kg body weight. Arthritis was evaluated on the last day of the experiment on the injected animal paw using X-ray computerized microtomography and histopathology analysis methods. The CETH effect was compared with the non-steroidal anti-inflammatory drug diclofenac sodium (5 mg/kg). Oral administration of CETH was accompanied by effective dose-dependent correction of morphological changes caused by the adjuvant injection. CETH had relatively high recovery effects in terms of parameters for reducing inflammation, inhibition of osteolysis, reduction in the inflammatory reaction of periarticular tissues, and cartilage degeneration. This study presents for the first time that CETH may be a powerful potential nutraceutical agent or bioactive component in the treatment of rheumatoid arthritis.

Efficacy and safety of Ramucirumab and methotrexate co-therapy in rheumatoid arthritis experimental model: Involvement of angiogenic and immunomodulatory signaling

Rheumatoid arthritis (RA) is a chronic and progressive autoimmune inflammatory disease associated with irreversible joint destruction that leads to permanent motor disability and compromised quality of life. However, the main cause of RA is still unknown though stimulation of immune system and cells plays pivotal role in disease development and progression. Ramucirumab (RAM) is the monoclonal antibody against VEGF- receptor. This study aimed to investigate and evaluate the therapeutic effect of RAM with or without Methotrexate (MTX) against adjuvant-induced arthritis in rats. Complete Freund's adjuvant (CFA)-induced arthritic rats were treated for three consecutive weeks with MTX or RAM alone and MTX-RAM co-therapy. Arthritic score, gait score, ankle diameter, paw thickness, angiogenic, inflammatory cytokines, bone erosion markers, and apoptotic markers were assessed to evaluate the anti-arthritic effect. RAM monotherapy exhibited anti-inflammatory, anti-angiogenic and anti-apoptotic effects similar to MTX alone to treat RA in the current study. Furthermore, RAM alone had a protective effect on bone and cartilage health better than standard anti-rheumatic agent MTX. Interestingly, combined therapy of MTX and RAM produced significant differences in comparison with MTX or RAM monotherapy in all tested parameters. Moreover, the current study proved that MTX-RAM co-therapy has a synergistic effect.

Effect of electroacupuncture at the ST36 and GB39 acupoints on apoptosis by regulating the p53 signaling pathway in adjuvant arthritis rats

p53 and mouse double minute 2 homolog (MDM2) serve key regulatory roles in the apoptosis of synovial cells. The present study aimed to investigate the effects of electroacupuncture (EA) at the 'Zusanli' (ST36) and 'Xuanzhong' (GB39) acupoints on apoptosis in an adjuvant arthritis (AA) rat model. A total of 40 male Sprague‑Dawley rats were randomly divided into Control, AA, AA + EA and AA + sham EA groups (n=10 rats in each group). Rats in all the groups, with the exception of the control group, were injected with Complete™ Freund's adjuvant into the bilateral hindlimb footpad to establish the AA model. Rats in the AA + EA group were treated with EA at the ST36 and GB39 acupoints. Rats in the AA + sham EA group were treated with percutaneous electrical stimulation at a position of 5 mm away from the ST36 and GB39 acupoints. The arthritis index scores and hindlimb paw volumes of the rats in each group were recorded. Subsequently, pathological changes in the synovial tissue were evaluated by hematoxylin and eosin (H&E) staining, and the apoptotic rate of the synovial cells was detected by TUNEL staining. In addition, the expression levels of the apoptosis‑associated proteins, Bax, phorbol‑12‑myristate‑13‑acetate‑induced protein 1 (Noxa) and p53 upregulated modulator of apoptosis (PUMA), were determined by western blot analysis. The expression of both the gene and protein of p53 and MDM2 in synovial tissue was detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, respectively. The results indicated that the arthritis index scores and hindlimb paw volumes upon EA stimulation were significantly decreased compared with those of the AA group (P<0.05). H&E staining revealed that the synovial inflammation of EA stimulation was significantly decreased compared with the AA group (P<0.05). The TUNEL assay results indicated that the apoptotic rate of synovial cells in the AA + EA group was significantly increased compared with that in the AA group (P<0.05). Furthermore, an increased expression of proapoptotic proteins was confirmed by the increased expression levels of Bax, Noxa and PUMA in the AA + EA group. The results of RT‑qPCR and western blot analysis demonstrated that, compared with the AA group, EA stimulation led to a marked increase in p53 (P<0.05) and a significant decrease in MDM2 (P<0.05) gene and protein expression. Taken together, these results demonstrated that EA performed on the ST36 and GB39 acupoints led to a significant amelioration in AA injury of model rats, by regulating the p53 signaling pathway and inducing apoptosis.

p53 predominantly regulates IL-6 production and suppresses synovial inflammation in fibroblast-like synoviocytes and adjuvant-induced arthritis

Background

Dominant-negative somatic mutations of p53 has been identified in the synovium of patients with rheumatoid arthritis (RA), in which interleukin (IL)-6 has been established as a pivotal inflammatory cytokine. The aim of this study was to clarify the significance of p53 in the longstanding inflammation in RA by modulating IL-6.

Methods

We established adjuvant-induced arthritis (AIA) in Lewis rats and treated them with p53 activator, and then analyzed the histopathology of the synovium and IL-6 expression. Human fibroblast-like synoviocytes (FLS) were cultured and transfected with p53-siRNA or transduced with adenovirus (Ad)-p53, and then assessed with MTT, TUNEL staining, and luciferase assay. IL-1β, tumor necrosis factor (TNF)-α and IL-17 were used to stimulate FLS, and subsequent IL-6 expression as well as relevant signal pathways were explored.

Results

p53 significantly reduced synovitis as well as the IL-6 level in the AIA rats. It controlled cell cycle arrest and proliferation, but not apoptosis. Proinflammatory cytokines inhibited p53 expression in FLS, while p53 significantly suppressed the production of IL-6. Furthermore, IL-6 expression in p53-deficient FLS was profoundly reduced by NF-kappaB, p38, JNK, and ERK inhibitors.

Conclusion

Our findings reveal a novel function of p53 in controlling inflammatory responses and suggest that p53 abnormalities in RA could sustain and accelerate synovial inflammation mainly through IL-6. p53 may be a key modulator of IL-6 in the synovium and plays a pivotal role in suppressing inflammation by interaction with the signal pathways in RA-FLS. Interfering with the p53 pathway could therefore be an effective strategy to treat RA.

Synovial tissue hypoxia and inflammation in vivo

INTRODUCTION

Hypoxia is a microenvironmental feature in the inflamed joint, which promotes survival advantage for cells. The aim of this study was to examine the relationship of partial oxygen pressure in the synovial tissue (tPO(2)) in patients with inflammatory arthritis with macroscopic/microscopic inflammation and local levels of proinflammatory mediators.

METHODS

Patients with inflammatory arthritis underwent full clinical assessment and video arthroscopy to quantify macroscopic synovitis and measure synovial tPO(2) under direct visualisation. Cell specific markers (CD3 (T cells), CD68 (macrophages), Ki67 (cell proliferation) and terminal deoxynucleotidyl transferase dUTP nick end labelling (cell apoptosis)) were quantified by immunohistology. In vitro migration was assessed in primary and normal synoviocytes (synovial fibroblast cells (SFCs)) using a wound repair scratch assay. Levels of tumour necrosis factor alpha (TNFalpha), interleukin 1beta (IL1beta), interferon gamma (IFNgamma), IL6, macrophage inflammatory protein 3alpha (MIP3alpha) and IL8 were quantified, in matched serum and synovial fluid, by multiplex cytokine assay and ELISA.

RESULTS

The tPO(2) was 22.5 (range 3.2-54.1) mm Hg and correlated inversely with macroscopic synovitis (r=-0.421, p=0.02), sublining CD3 cells (-0.611, p<0.01) and sublining CD68 cells (r=-0.615, p<0.001). No relationship with cell proliferation or apoptosis was found. Primary and normal SFCs exposed to 1% and 3% oxygen (reflecting the median tPO(2) in vivo) induced cell migration. This was coupled with significantly higher levels of synovial fluid tumour necrosis factor alpha (TNFalpha), IL1beta, IFNgamma and MIP3alpha in patients with tPO(2) <20 mm Hg (all p values <0.05).

CONCLUSIONS

This is the first study to show a direct in vivo correlation between synovial tPO(2), inflammation and cell migration, thus it is proposed that hypoxia is a possible primary driver of inflammatory processes in the arthritic joint.

Fibroblast-like synoviocytes: key effector cells in rheumatoid arthritis

Rheumatoid arthritis (RA) remains a significant unmet medical need despite significant therapeutic advances. The pathogenesis of RA is complex and includes many cell types, including T cells, B cells, and macrophages. Fibroblast-like synoviocytes (FLS) in the synovial intimal lining also play a key role by producing cytokines that perpetuate inflammation and proteases that contribute to cartilage destruction. Rheumatoid FLS develop a unique aggressive phenotype that increases invasiveness into the extracellular matrix and further exacerbates joint damage. Recent advances in understanding the biology of FLS, including their regulation regulate innate immune responses and activation of intracellular signaling mechanisms that control their behavior, provide novel insights into disease mechanisms. New agents that target FLS could potentially complement the current therapies without major deleterious effect on adaptive immune responses.

Effect of total flavonoids of Chrysanthemum indicum on the apoptosis of synoviocytes in joint of adjuvant arthritis rats

Chrysanthemum is a traditional Chinese medicine used in China to treat inflammatory diseases. The total flavonoids Chrysanthemum indicum (TFC) were extracted from the dried bud of Chrysanthemum indicum. Our previous study had demonstrated that TFC was a new class of effective anti-inflammation, analgesia and immunoloregulation agents. In this study, we established an adjuvant arthritis (AA) model by injection of Freund's Complete Adjuvant (FCA) to investigate the effect of TFC on the apoptosis of synoviocytes in AA Rats. Synoviocytes isolated from knee joint of rats were treated with different doses of TFC in vitro. Synoviocytes proliferation was measured by MTT assay, and DNA fragmentations were evaluated on agarose gel electrophoresis. The levels of caspase-3 cleaved fragments were analyzed by Western blot. The annexin V stain assay was used to explore the inhibition of caspase-3 on the amelioration of synoviocytes apoptosis. The results showed that TFC inhibited the proliferation of synoviocytes. Electrophoresis showed higher ladders of DNA bands in the TFC group. Cleaved fragments of caspase-3 were increased significantly. Furthermore, the apoptotic synoviocytes were markedly decreased by the caspase-3 specific inhibitor. These results suggest that TFC could induce synoviocytes apoptosis and suppress proliferation of synoviocytes in adjuvant-induced arthritis rats.

Salubrious effect of Kalpaamruthaa, a modified indigenous preparation in adjuvant-induced arthritis in rats--a biochemical approach

BACKGROUND

Interactions between the phytochemicals and drugs and their combinations are capable of providing longer remissions and perhaps a complete cure for many diseases including rheumatoid arthritis (RA). In addition to articular manifestations in RA, extra-articular signs involving reticuloendothelial and hepatic systems are an indication of more severe disease and thus, have prognostic value.

OBJECTIVES

The present study was designed to illustrate the beneficial outcome of the drug Kalpaamruthaa (constituting Semecarpus anacardium nut milk extract, fresh dried powder of Emblica officinalis fruit and honey) in adjuvant-induced arthritic rat model with respect to the changes in extra-articular manifestation involving hematological and cellular constituents.

MATERIAL AND METHODS

Levels of hematological parameters, cellular constituents, activities of marker enzymes and the level of DNA damage were assessed in control, arthritis-induced, SA, KA and drug control treated rats.

RESULTS AND CONCLUSION

Significant decrease (p<0.005) in the levels of Hb, RBC, PCV, total protein, albumin, A/G ratio, plasma uric acid, urinary urea, uric acid, creatinine, FFA, HDL and significant increase (p<0.05) in the levels of WBC, platelet count, ESR, globulin, plasma creatinine, blood glucose, urea, AST, ALT, ALP, TC, FC, TG, PL, LDL and VLDL were observed in arthritic rats. No other significant change was observed in tissue DNA and RNA levels of control and experimental animals. On the contrary an increase in DNA damage was observed in arthritic rats when compared to control animals. The above said derangements were brought back to near normal levels upon SA and KA treatments and KA revealed a profound beneficial effect than SA. The enhanced effect of KA might be attributed to the combined effects of phytoconstituents such as flavonoids, tannins and other compounds such as vitamin C present in KA. Thus KA via this preliminary protective effect might contribute to the amelioration of the disease process.

Relationship between TNF-alpha and TUNEL-positive chondrocytes in antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND

Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end-labeling (TUNEL) staining is a widely accepted method for the detection of DNA fragmentation in nuclei of apoptotic cells. Tumor necrosis factor (TNF)-alpha is closely associated with changes in condylar cartilage and modulates apoptosis in various tissues including cartilage. The aim of this study was to investigate the relationship between apoptotic chondrocytes and TNF-alpha in a rabbit model of arthritis.

METHOD

Unilateral temporomandibular joint (TMJ) arthritis was induced in 20 adult New Zealand White rabbits. From 1 day to 6 weeks after the induction of arthritis, immunohistochemical analysis for TNF-alpha and TUNEL was performed.

RESULTS

In condylar cartilage, TNF-alpha-positive cells and TUNEL-positive cells were localized together. TNF-alpha-positive chondrocytes seemed to precede TUNEL-positive cells.

CONCLUSIONS

The results of the present study suggest that TNF-alpha may be involved in apoptosis and/or apoptotic necrosis of chondrocytes as TMJ arthritis progresses from the acute to chronic stage.

Anti-arthritic Effects of Ephedra sinica STAPF Herb-Acupuncture: Inhibition of Lipopolysaccharide-Induced Inflammation and Adjuvant-Induced Polyarthritis

Anti-inflammatory and anti-arthritic effects of water distillates of Ephedra sinica STAPF (ES), in herb-acupuncture, on the inflammatory responses of arthritis was investigated using phorbol 12-myristate 13-acetate (PMA)/lipopolysaccharide (LPS)-induced human macrophage and adjuvant-induced arthritic rat. The luciferase reporter vectors driven by the tumor necrosis factor (TNF)-alpha and cyclooxygenase-2 promoters were transiently transfected into U937 cells, which were then differentiated and stimulated by PMA and LPS, respectively, to develop an in vitro anti-inflammation assay system. The luciferase activities, observed in the activated U937 cells, were significantly inhibited by ES herb-acupuncture, compared to those of PD98509 and berberine. To evaluate ES herb-acupuncture as a novel anti-arthritic therapy, a polyarthritic rat model was developed using heat-killed Mycobacterium tuberculosis, and 50 mul of ES distillate was subcutaneously injected into the ST36 acupoint on each knee joint. While the articular indexes of arthritic rats were evidently decreased by ES herb-acupuncture, their body weights did not regain their initial levels. This may be due to the accelerating effects of ES on weight-loss and fat consumption. The mRNA expressions of TNF-alpha and interleukin (IL)-6 genes, which were closely stimulated in the arthritic rat joints, were found to be restored to the normal levels through the ES treatment. In the case of IL-1beta, the recovery was not significant but substantial. The anti-arthritic effect of ES herb-acupuncture was not found in the ES-treated/non-acupoint group. In conclusion, the ES herb-acupuncture into the ST36 acupoint was found to be effective in alleviating the inflammatory response and thus arthritic symptoms in adjuvant-induced arthritic rats.

Apoptosis as a mechanism of autoimmune inflammation in human knee joint

Apoptosis in the cartilage and synovial membrane of the knee joint in patients with rheumatoid arthritis was studied using the immunocytochemical TUNEL method. The degree of apoptosis correlated with the duration of inflammation. The process predominated in the chondroblast population, lymphocytic infiltration, and synovial membrane fibroblasts.

p53 is required for spontaneous autoantibody production in B6/lpr lupus mice

The p53 tumor suppressor molecule triggers a key pathway of apoptosis in injured cells, in part through induction of Fas. The importance of Fas as a receptor mediating apoptosis is highlighted by the lupus-like systemic autoimmunity seen in animals and humans with nonfunctional Fas molecules. We set out to see if the absence of p53, superimposed on the Fas defect of lpr mice, might further accelerate or exacerbate their systemic autoimmunity. We generated double mutant mice (p53(-/-) lpr) having defects in both p53- and Fas-dependent pathways, hypothesizing that animals with lesions in both Fas- and p53-dependent pathways would show reduced ability to delete autoreactive or injured cells, thereby producing more severe autoimmune disease. Surprisingly, these mice have lower autoantibody levels than the single mutant lpr mice. These studies suggest an unanticipated role for p53 in the progression of autoimmunity and the production of autoantibodies.

p53 expression in rheumatoid and psoriatic arthritis synovial tissue and association with joint damage

BACKGROUND

Overexpression and functional mutations of p53 have been found in the synovial tissue (ST) of patients with rheumatoid arthritis (RA), but their clinical significance remains unclear.

OBJECTIVE

To analyse p53 expression in the ST of patients with RA and psoriatic arthritis (PsA) and its association with joint damage.

METHODS

Synovial biopsy specimens were obtained by arthroscopy in 45 patients (27 RA, 18 PsA). Radiographs of hands, feet, and the joint undergoing arthroscopy were obtained to evaluate the presence of erosive disease. Synovial cell populations were analysed using CD4, CD8, CD138, CD20, and CD68 monoclonal antibodies (mAbs). The p53 protein was determined by immunohistology using DO7 mAb in 34 patients (18 RA, 16 PsA). In 11 patients with early RA, the association between p53 and 1 year progression of radiographic damage was analysed using the Larsen-Scott method.

RESULTS

The p53 protein was detected in 16/18 (89%) patients with RA and in 9/16 (56%) patients with PsA, but its expression in RA was significantly higher than in PsA. In RA, p53 expression was significantly associated with erosive disease, and its scores were higher in patients with radiological progression. CD68 expression was also associated with erosions and radiological progression in RA. No association was found between either p53 or CD68 and erosive disease in PsA.

CONCLUSIONS

These results suggest that p53 ST overexpression and association with joint damage is characteristic of RA rather than PsA, and that p53 ST expression might be a prognostic marker of joint damage in RA.

Potential role of heme oxygenase-1 in the progression of rat adjuvant arthritis

Rat adjuvant arthritis is an experimental model widely used to evaluate etiopathogenetic mechanisms in chronic inflammation. We have examined the participation of heme oxygenase-1 (HO-1) in this experimental arthritis. In this study, an increased nitric oxide (NO) production in the paw preceded the upregulation of HO-1, whereas selective inhibition of inducible NO synthase (iNOS) after the onset of arthritis decreased HO-1 expression, suggesting that the induction of this enzyme may depend on NO produced by iNOS. Therapeutic administration of the HO-1 inhibitor tin protoporphyrin IX was able to control the symptoms of arthritis. This agent significantly decreased leukocyte infiltration, hyperplastic synovitis, erosion of articular cartilage and osteolysis, as well as the production of inflammatory mediators. In this experimental model, HO-1 can be involved in vascular endothelial growth factor production and angiogenesis. These results support a role for HO-1 in mediating the progression of the disease in this model of chronic arthritis.

Gene therapy in animal models of rheumatoid arthritis: are we ready for the patients?

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the synovial joints, with progressive destruction of cartilage and bone. Anti-tumour necrosis factor-α therapies (e.g. soluble tumour necrosis factor receptors) ameliorate disease in 60–70% of patients with RA. However, the need for repeated systemic administration of relatively high doses in order to achieve constant therapeutic levels in the joints, and the reported side effects are downsides to this systemic approach. Several gene therapeutic approaches have been developed to ameliorate disease in animal models of arthritis either by restoring the cytokine balance or by genetic synovectomy. In this review we summarize strategies to improve transduction of synovial cells, to achieve stable transgene expression using integrating viruses such as adeno-associated viruses, and to achieve transcriptionally regulated expression so that drug release can meet the variable demands imposed by the intermittent course of RA. Evidence from animal models convincingly supports the application of gene therapy in RA, and the feasibility of gene therapy was recently demonstrated in phase I clinical trials.

Tumour necrosis factor-alpha and apoptosis in the rat temporomandibular joint

The purpose of this investigation was to investigate the roles that tumour necrosis factor-alpha (TNF-alpha) and apoptosis play during acute inflammation of the temporomandibular joint (TMJ). Adult male Sprague-Dawley rats were injected with complete Freund's adjuvant (CFA) into the TMJ or kept as uninjected controls. The TMJ tissues were removed 2 days post-injection to mimic conditions of acute inflammation and analysed for changes in expression of TNF-alpha, the receptor TNF-R1, caspase-3 and -8, and apoptosis. Concentrations of TNF-alpha, TNF-R1, caspase-3 and -8, and apoptosis were significantly elevated in CFA-injected animals compared to uninjected controls. Tissue incubation with TNF-alpha caused a significant increase in caspase-3 and -8. Also, levels of apoptosis were significantly increased during inflammation, which could be inhibited by the addition of either anti-TNF-alpha neutralising antibody or caspase inhibitors. TNF-alpha may play a significant role in the onset of acute CFA-induced TMJ inflammation, and activation of apoptosis signalling pathways may be involved.

p53 in rheumatoid arthritis synovial fibroblasts at sites of invasion

OBJECTIVE

To analyse the functional response of p53 in rheumatoid arthritis synovial fibroblasts (RASF) in vitro and in vivo and to investigate whether activation of p53 modulates the destructive process of RASF.

METHODS

RASF and controls grown on chamber slides were either directly examined with DO7 anti-p53 antibodies by immunofluorescence or irradiated with 10 Gy x rays and analysed time dependently for the expression of p53. The percentage of positive cells was evaluated by a quantitative scoring system. RASF and normal (N) SF cultured in vitro were co-implanted with human cartilage in SCID mice for 60 days. Consecutively, the invasion score was evaluated, and the number of p53 positive cells was determined at the sites of invasion by immunohistochemistry. In addition, synovial tissues from RA, osteoarthritis, and normal synovia were stained with DO7 antibodies.

RESULTS

In vitro the rate of expression of p53 in RASF was low (<5%), but transiently inducible by ionising irradiation (50%). In vitro low p53 expressing RASF disclosed, when invading articular cartilage, a nuclear p53 signal in 20% of the cells, indicating the induction of p53 in a distinct population of RASF during the invasive process.

CONCLUSIONS

These data suggest an inductive p53 response at sites of cartilage invasion during the destructive process driven by activated RASF.

Regulation of p53 by macrophage migration inhibitory factor in inflammatory arthritis

OBJECTIVE

To study the capacity of macrophage migration inhibitory factor (MIF) to regulate proliferation, apoptosis, and p53 in an animal model of rheumatoid arthritis (RA) and in fibroblast-like synoviocytes (FLS) from humans with RA.

METHODS

Antigen-induced arthritis (AIA) was induced in MIF(-/-) mice and littermate controls. FLS were obtained from patients with RA. Western blotting and immunohistochemistry were used to measure p53 in cells and tissues. Apoptosis was detected in cells by flow cytometry using TUNEL and annexin V/propidium iodide labeling. Apoptosis in tissue was detected using TUNEL. Proliferation was assessed in cultured cells and tissue by (3)H-thymidine incorporation and Ki-67 immunostaining, respectively.

RESULTS

MIF inhibited p53 expression in human RA FLS. Levels of p53 were correspondingly increased in MIF(-/-) mouse tissues and cells. Spontaneous and sodium nitroprusside-induced apoptosis were significantly increased in MIF(-/-) cells. In vitro exposure of FLS to MIF reduced apoptosis and significantly induced FLS proliferation. Synoviocyte proliferation in MIF(-/-) mice was correspondingly reduced. A decrease in the severity of AIA in MIF(-/-) mice was associated with an increase in p53 and apoptosis in synovium. Evidence of in situ proliferation was scant in this model, and no difference in in situ proliferation was detectable in MIF(-/-) mice compared with wild-type mice.

CONCLUSION

These results indicate a role for MIF in the regulation of p53 expression and p53-mediated events in the inflamed synovium and support the hypothesis that MIF is of critical importance in the pathogenesis of RA.

Cell characterization of mononuclear and giant cells constituting pigmented villonodular synovitis

The aim of this study was to determine the histologic and cellular characteristics of 2 cell types, mononuclear cells (Mos) and multinuclear giant cells (GCs), that predominantly constitute pigmented villonodular synovitis (PVS). Synovial tissues examined in this study were obtained from 10 patients with PVS. Five methods were used for cell analysis: (1) enzyme-histochemistry for tartrate-resistant acid phosphatase (TRAP); (2) immunohistochemistry using antibodies for CD68, macrophage colony-stimulating factor (M-CSF), MIB-1, p53, p21, p16, and cathepsin-L (cath L); (3) TdT-mediated deoxyuridine triphosphate-biotin terminal end labeling (TUNEL) as a measure of apoptosis; (4) fluorescence-based polymerase chain reaction single-strand conformation polymorphism analyses (FPCR-SSCP) to detect p53 gene mutations; and (5) in situ hybridization using gene-specific oligoprobes for matrix metalloproteinase (MMP)-2, MMP-9, receptor activator of nuclear factor kappaB ligand (RANKL), and calcitonin receptor (CTR). Both Mos and GCs were shown to express the macrophage/histiocyte marker CD68. In GCs, TRAP and CTR, both of which are known as characteristic phenotype markers of osteoclasts, were expressed. M-CSF and RANKL, which are together essential for osteoclast differentiation, were expressed in both Mos and GCs. Mos were shown to express MIB-1, but GCs were not. Although proliferation-suppressor proteins p53, p21, and p16 were expressed in both Mos and GCs, little apoptotic phenomenon of lining Mos was detected by TUNEL. In our study, p53 gene mutations for exons 5, 7, and 8 in PVS synovial tissues were not detected by FPCR-SSCP analysis. Furthermore, both types of cells demonstrated the proteolytic enzymes MMP-2 and MMP-9 mRNA, and cath L protein. These results suggest that PVS has a hyperplastic property consisting of the CD68-positive monocytic cell lineage with differentiation of osteoclastic giant cells from monocyte and probably controlled against proliferation by wild-type p53, p21, and p16.

Therapeutic Effects of Hominis placenta Injection into an Acupuncture Point on the Inflammatory Responses in Subchondral Bone Region of Adjuvant-Induced Polyarthritic Rat

Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovial membrane in the joint, which leads to the progressive destruction of articular cartilage, ligament and bone. Several cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), and interleukin 6 (IL-6) have been implicated in the pathological mechanisms of synovial tissue proliferation, joint destruction and programmed cell death in rheumatoid joint. In the Korean traditional medicine, Hominis placenta (HP) as an herbal component of herb-acupuncture has been widely used to treat chronic inflammatory diseases such as RA. To study the therapeutic effects of HP injection into the ST36 acupoint (HP herb-acupuncture) on the inflammatory responses of a subchondral region of rheumatoid joint, the polyarthritis-induced Sprague-Dawley (SD) rat was developed as a rheumatoid arthritis model by the intradermal injection of dried cells of Mycobacterium tuberculosis emulsified in squalene to the base of tail. After the onset stage (11 d after adjuvant injection) of polyarthritis, a fixed volume of HP extract was daily injected to Zusanli (ST36) acupoint on the rat's leg for 2 weeks. The body weight, paw volume of the knee joint and articular index were exploited as an assessment method addressing arthritic symptoms, and the expression profiles of TNF-alpha, IL-1beta and IL-6 at the subchondral bone of the joint were analyzed using an immunohistochemistry. After the treatment of arthritic rats with HP, the body weights and paw volumes of arthritic rats were almost restored to the levels of normal rats whereas the evaluation by the articular index was not remarkable. The TNF-alpha, IL-1beta and IL-6 positive cells in the immunohistological sections of subchondral bone region of the joint significantly decreased in HP-treated (ST36 acupoint) arthritic group as compared with those in non-treated or HP-treated (non-acupoint) ones, which was coincident with the behavioral studies. In conclusion, the HP herb-acupuncture was found to be effective to alleviate the arthritic symptoms in adjuvant-induced arthritis rats as regards the body weight, joint appearance and the expression profiles of inflammatory cytokines.

Streptococcal cell wall arthritis: kinetics of immune cell activation in inflammatory arthritis

The streptococcal cell wall model of arthritis in Lewis rats consists of an acute, non-T-cell-dependent initiation phase, followed by a remission and then a chronic, inflammatory T-cell-dependent phase. In this report, we define pertinent changes in the cognate and noncognate immune system of the Lewis rats during various phases of the disease. We examined changes in the population size of various cell types using lineage-specific markers in three different tissues (blood, spleen, and lymph nodes) over 28 days. Our results indicate that the T cell and monocyte populations were significantly altered in PG-PS-treated rats and the activation status of these cells parallel initiation, remission, and chronic phases of joint inflammation. Activation of B cells also increases in certain tissues in the chronic phase of the disease. In summary, our results confirm the involvement of both innate and cognate immunity in the development of arthritis and demonstrate that monocytes, in addition to T cells, play a substantive role in the induction and maintenance of the inflammatory process in this rat model.

The genetics of the target tissue in rheumatoid arthritis

The genetic mechanisms that are complementary in predisposing and then establishing disease are yet to be fully elucidated. During a lifetime, the genetic composition of the host is not only hereditary but undergoes rearrangements, integrations, and more subtle single-base pair alterations. These changes can be inconsequential or lead to aberrant and deleterious pathologic changes. In a complex multifactorial disease such as RA, the relative roles of the dynamic versus germline elements of the disease have yet to be fully determined. Further studies of large populations are likely to segregate out factors affecting specific ethnic, clinical, and genetic subgroups.

Regulation of joint destruction and inflammation by p53 in collagen-induced arthritis

The role of the tumor suppressor p53 as a key regulator of inflammation was examined in murine collagen-induced arthritis (CIA), a model of rheumatoid arthritis. Wild-type DBA/1 mice develop progressive arthritis in this model, in which p53 expression and apoptosis are evident in the synovial cells. In contrast, the joints of p53(-/-) DBA/1 animals with CIA showed increased severity of arthritis using clinical and histological scoring methods with almost no apoptosis. Consistent with this, collagenase-3 expression and cytokine production (interleukin-1 and interleukin-6) in the joints of p53(-/-) mice with CIA were significantly greater than in wild-type mice. Anti-collagen antibody titers, however, were not different. Therefore, p53 expression occurs during inflammation and acts to suppress local inflammatory responses. Because mutations in p53 have been described in the synovial membrane of rheumatoid arthritis patients, the loss of p53 function in synoviocytes or other cells in the joint because of dominant-negative mutations might contribute to invasion and destruction of the joint in this disease.

Differential expression pattern of the antiapoptotic proteins, Bcl-2 and FLIP, in experimental arthritis

OBJECTIVE

To examine the relationship between apoptosis and the expression of antiapoptotic proteins in the pathogenesis of experimental inflammatory arthritis.

METHODS

Clinical and histologic assessment of adjuvant-induced arthritis (AIA) was performed over a 42-day period. The induction of apoptosis was measured by TUNEL analysis, and the antiapoptotic proteins, Bcl-2 and FLIP, were examined by immunohistochemistry with the use of monospecific antibodies. The percentage of Bcl-2- and FLIP-positive cells was correlated with histologic markers of AIA.

RESULTS

Arthritis developed by day 14 following adjuvant injection. Few TUNEL-positive cells were observed between days 0 and 21, indicating that apoptosis did not occur at these time points. An increase in the number of TUNEL-positive cells was observed at day 28, particularly outside sites of cartilage or bone erosion, which dramatically declined by day 35. Immunohistochemical analyses of Bcl-2 and FLIP revealed that the synovium was positive for Bcl-2 and FLIP on day 0. On day 14, Bcl-2 was present at the sites of early erosions and correlated with the erosion and inflammation scores. FLIP was also highly expressed at sites of erosion and was localized to the pannus starting on day 21. Although TUNEL positivity peaked at day 28, a time point in which Bcl-2 and FLIP were present, the areas that displayed intense positivity for expression of Bcl-2 and FLIP were TUNEL negative. In addition, the number of neutrophils in the synovial lining and pannus significantly decreased from day 28 to day 35, suggesting that the cells undergoing apoptosis were neutrophils. Furthermore, at day 42 when TUNEL-positive cells were absent, Bcl-2 expression was diminished, while FLIP remained highly expressed in the pannus.

CONCLUSION

The overall percentage of TUNEL-positive cells in the ankle was <1% except on days 28 and 35 post-adjuvant injection, suggesting that in AIA, similar to rheumatoid arthritis, a lack of apoptosis may contribute to disease progression. Furthermore, Bcl-2 and FLIP are temporally and differentially expressed during the pathogenesis of AIA. Inhibition of these molecules may augment synovial apoptosis and ameliorate the disease.

Inhibitor of nuclear factor kappaB kinase beta is a key regulator of synovial inflammation

OBJECTIVE

Inhibitor of nuclear factor kappaB kinase beta (IkappaB kinase beta, or IKKbeta) has emerged as a key regulator of the transcription factor nuclear factor kappaB (NF-kappaB). Since IKKbeta could have both pro- and antiinflammatory activity, we examined whether its constitutive activation was sufficient to cause a chronic inflammatory disease such as rheumatoid arthritis.

METHODS

Normal Lewis rats were evaluated for paw swelling by plethysmometry and histologic assessment after intraarticular injection of an adenoviral construct encoding the IKKbeta wild-type gene (Ad.IKKbeta-wt); controls received an adenoviral construct encoding green fluorescent protein (Ad.GFP). The rats were killed after 7 days. Additionally, rats were killed 48 hours after intraarticular injection of Ad.IKKbeta-wt or Ad.GFP for studies of IKK activity and NF-kappaB binding. For studies of the effects of inhibition of IKKbeta activity, Lewis rats were immunized with Mycobacterium tuberculosis in mineral oil. The ankle joints were injected on day 12 with an adenoviral construct encoding IKKbeta K-->M (dominant negative, IKKbeta-dn) or Ad.GFP. We evaluated paw swelling and NF-kappaB expression on day 25.

RESULTS

Intraarticular gene transfer of IKKbeta-wt into the joints of normal rats resulted in significant paw swelling and histologic evidence of synovial inflammation. Increased IKK activity was detectable in the IKKbeta-wt-injected ankle joints, coincident with enhanced NF-kappaB DNA binding activity. Intraarticular gene transfer of IKKbeta-dn significantly ameliorated the severity of adjuvant arthritis, accompanied by a significant decrease in NF-kappaB DNA expression in the joints of Ad.IKKbeta-dn-treated animals.

CONCLUSION

IKKbeta plays a key role in rodent synovial inflammation. Intraarticular gene therapy to inhibit IKKbeta activity represents an attractive strategy for the treatment of chronic arthritis.

Gene transfer of p53 to arthritic joints stimulates synovial apoptosis and inhibits inflammation

Rheumatoid arthritis (RA) is an autoimmune disease that primarily affects joints. During the pathogenesis of rheumatoid arthritis, the synovial lining becomes dramatically thickened and hyperplastic. This highly aggressive tissue invades and destroys articular cartilage and bone. Several lines of evidence suggest that the proliferation of the synovial tissue may be due to disruption in the control of the cell cycle or apoptotic pathways. In particular, mutations in the tumor suppressor protein p53 have been found in synovial tissue from RA joints. We have examined the effects of overexpression of p53 by adenoviral infection in synovial cells in culture and in synovial tissue in vivo in a rabbit model of arthritis. Here we demonstrate that p53 overexpression resulted in significant apoptosis in human and rabbit synovial cells in culture. Furthermore, intraarticular injection of Ad-p53 resulted in extensive and rapid induction of synovial apoptosis in the rabbit knee without affecting cartilage metabolism. Interestingly, a significant reduction in the leukocytic infiltrate was observed within 24 h postinfection of Ad.p53. These results suggest that intraarticular gene transfer of p53 is able to induce synovial apoptosis as well as reduce inflammation and thus may be useful clinically for the treatment of RA.

Is early rheumatoid arthritis the same disease process as late rheumatoid arthritis?

Thoughts on treatment for the early control of synovitis have stimulated research on pathobiological events at the site of inflammation in patients with early rheumatoid arthritis. Several studies have thus been conducted to examine synovial biopsy samples at various stages of the disease. The most important conclusion from these studies is that all features of chronic synovial inflammation can be observed in so-called early rheumatoid arthritis. This suggests that no arguments exist for the effect of therapeutic intervention on synovitis varying in different phases of rheumatoid arthritis. In end-stage rheumatoid arthritis, factors that are secondary to the disease may contribute to the perpetuation of synovial inflammation. Mutations in key regulatory genes could play a role in the autonomous progression of the disease. In addition, it is conceivable that the release of bone and cartilage fragments might elicit an inflammatory response in patients with destructive rheumatoid arthritis.

Rheumatoid arthritis viewed using a headache paradigm

Results and new hypotheses in animal models often stimulate development of new paradigms in how we view rheumatoid arthritis (RA). The complexity of RA does, however, eventually lead to the rejection of these hypotheses. Here, it is argued that the large number of so-far described animal models, when taken together, also reveals a complex disease. Fortunately, detailed study of each of the animal models will reveal this complexity, and may also be helpful in elucidating the complexity of the human disease. Benoist and Mathis [1] recently contributed a new animal model in which an autoimmune response to a ubiquitous antigen leads to an antibody-mediated inflammatory attack in the joints. It is argued that this new model, as with other animal models, is unlikely to explain RA, but it will add to the tools available to reveal the complexity of RA.

p53 in rheumatoid arthritis: friend or foe?

The knowledge of transcription factors and proto-oncogenes has influenced the understanding of cell regulation, cell cycle, and apoptotic cell death in rheumatoid arthritis (RA) synovium. In addition, the development of normal synovial fibroblasts into transformed-appearing aggressive synovial fibroblasts may be triggered by the lack of antiproliferative factors, such as p53, p53-associated molecules, other tumor suppressors, as well as by upregulation of anti-apoptotic genes. Therefore, data derived from experiments such as those performed by Tak and colleagues in this issue of Arthritis Research not only enrich the intensive discussion addressing the impact of p53 on RA pathophysiology, they also may facilitate development of novel therapeutic approaches including p53-targeted gene therapy.