Active leflunomide metabolite inhibits interleukin 1beta, tumour necrosis factor alpha, nitric oxide, and metalloproteinase-3 production in activated human synovial tissue cultures

Different modalities to manage rheumatoid arthritis: an A to Z story

Aim: To investigate different approaches to RA treatment that might lead to greater efficacy and better safety profiles. Methods: The Search strategy was based on medical subject headings, and screening and selection were based on inclusion/exclusion criteria. Results & discussion: Early therapy is critical for disease control and loss of bodily function. The most promising outcomes came from the development of disease-modifying anti-rheumatic drugs. Different foods have anti-inflammatory and antioxidant qualities that protect against the development of rheumatoid arthritis (RA). Some dietary patterns and supplements have been shown to have potential protective benefits against RA. Conclusion: Improvement in the quality of life of RA patients requires a tailored management approach based on the current patient medical data.

Metabolic syndrome and the decreased levels of uric acid by leflunomide favor redox imbalance in patients with rheumatoid arthritis

Oxidative stress plays a role in the pathophysiology of rheumatoid arthritis (RA). The aim of the present study was to verify the influence of metabolic syndrome (MetS) and disease-modifying antirheumatic drugs on nitrosative and oxidative biomarkers in patients with RA. A total of 177 patients with RA and 150 healthy volunteers participated in this study, which measured lipid hydroperoxides, advanced oxidation protein products (AOPP), nitric oxide metabolites (NOx), carbonyl protein, total radical-trapping antioxidant parameter (TRAP), uric acid (UA), and C-reactive protein (CRP). NOx and the NOx/TRAP ratio were significantly increased in RA, while no significant differences in lipid hydroperoxides, AOPP, UA, and TRAP levels were found between both groups. Treatment with leflunomide was associated with increased levels of carbonyl protein, and lowered levels in TRAP and UA, while the NOx/TRAP ratio further increased. NOx and the NOx/TRAP ratio were significantly higher in women than in men, while TRAP and UA were significantly lower in women. MetS was accompanied by increased AOPP and UA levels. RA was best predicted by increased NOx/TRAP ratio, CRP, and BMI. In conclusion, our data demonstrated that NOx and NOx/TRAP are strongly associated with RA physiopathology. Our findings suggest that inhibition of iNOS may become an interesting therapeutic approach for the treatment of RA. In addition, the presence of MetS and a decrease in levels of UA by leflunomide favor redox imbalance in RA patients. More studies are needed to evaluate the impact of antioxidant capacity reduction on RA progression.

Somatic antigens of tropical liver flukes ameliorate collagen-induced arthritis in wistar rats

Parasitic helminths polarize immune response of their vertebrate hosts towards anti-inflammatory Th2 type and therefore it is hypothesized that they may suppress the inflammatory conditions in autoimmune disorders. The present study was undertaken to investigate in vivo immunomodulatory and therapeutic potential of somatic antigens (Ag) of liver infecting digenetic trematodes [Fasciola gigantica (Fg) and Gigantocotyle explanatum (Ge)] in collagen-induced arthritic (CIA) Wistar rats. The CIA rats were administered subcutaneously with different doses (50 μg, 100 μg and 150 μg) of somatic antigens of Fg and Ge, daily for 21 days, the time period required to establish infection in natural host (Bubalus bubalis). Thereafter, the control, diseased and treated rats were compared for different parameters viz. hind paw thickness; serum interleukins, IL-4 and IL-10, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ); expression level of matrix metalloproteinases (MMPs) -2, -9, -13 and nitric oxide (NO) in knee joints and patellar morphology. The CIA rats treated with different antigens, Fg-Ag and Ge-Ag, show significant amelioration of the disease by down regulation of serum TNF-α and IFN-γ (p< 0.05) and upregulation of IL-4 and IL-10 cytokines (p< 0.05); inhibition (p< 0.05) of MMPs (-2,-9,-13) and NO in knee joints and improved patellar morphology with decreased synovial hypertrophy and reduced infiltration of ploymorphonuclear cells. The activity of pro as well as active MMPs (-2 and -9) and active MMP-13 in knee joints of CIA rats was very high compared to the control and treatment groups, suggesting the extent of collagen degradation in CIA rats. Interestingly, the highest dose (150 μg) of Ge-Ag almost wiped out MMP-13 expression. The overall findings suggest that the somatic proteins of Ge-Ag appeared to be therapeutically more effective than Fg-Ag, reflecting interspecific molecular differences which could contribute to the ability of these worms to successfully ameliorate the pathology of CIA.

The effect of leflunomide on cold and vibratory sensation in patients with rheumatoid arthritis

Objective

To evaluate the prevalence and risk factors of peripheral neuropathy in patients with rheumatoid arthritis (RA) treated with leflunomide (LEF) by quantitative sensory testing (QST).

Method

A total of 94 patients were enrolledin this study, out of which 47 patients received LEF. The other 47 patients received alternative disease-modifying antirheumatic drugs and served as the control group. The demographic characteristics, laboratory findings, concomitant diseases, and medication history were evaluated at the time of QST. The cooling (CDT) and vibratory detection threshold (VDT) as the representative components of QST were measured.

Results

Age, gender, RA duration, ESR, and CRP did not show any significant differences between the two groups. VDT did not demonstrate any significant difference in both groups. However, CDT in LEF group was significantly higher than that of the control group (8.6±2.7 in LEF vs. 5.6±3.8 in control). The proportion of RA patients in the LEF group showing abnormally high CDT was over 2 times greater than that of the control group, but these findings were not statistically significant. Age, RA duration (or LEF medication in LEF group), ESR, and CRP did not show significant correlation with CDT in both groups. VDT significantly correlated with age in both groups.

Conclusion

LEF treatment in patients with RA may lead to abnormal CDT in QST. CDT value was not affected by age, RA duration, disease activity, or LEF duration. It remains to be determined whether QST may be a valuable non-invasive instrument to evaluate the early sensory changes in patients with RA taking LEF.

Inhibiting effects of Leflunomide metabolite on overexpression of CD147, MMP-2 and MMP-9 in PMA differentiated THP-1 cells

Recent studies have reported elevated expression of cluster of differentiation (CD) 147 on CD14(+) monocytes of the peripheral blood of patients with active rheumatoid arthritis and a correlation of CD147 expression with Disease Activity Score. Thus, CD147 may be a new target for treatment of rheumatoid arthritis. Leflunomide is a disease-modifying antirheumatic drug that is commonly used to treat rheumatoid arthritis. The effect of leflunomide in blocking the up-regulation of CD147 and in blocking the down-regulation of metalloproteinases (MMP)-2 and MMP-9 in active macrophages has not yet been established. In this study we investigated the effect of A771726, the active metabolite of leflunomide, on expression of CD147 and on the gelatinolytic activity of MMP-2 and MMP-9 in phorbol myristate acetate (PMA) differentiated THP-1 cells. The expression of CD147, MMP-2, and MMP-9 mRNAs were determined by real-time quantitative reverse transcription PCR, the levels of cellular surface expression of CD147 were determined by flow cytometry, and the gelatinolytic activity of MMP-2 and MMP-9 were determined by zymography. Our results showed that A771726 significantly inhibited the expression of CD147 on the cell surface of activated THP-1 cells in a dose-dependent manner (P<0.01), inhibited the expression of MMP-2 and MMP-9 mRNAs in a dose-dependent manner (P<0.01), and inhibited the gelatinolytic activity of MMP-2 and MMP-9 at concentration of 15 μg/ml and 45 μg/ml (P<0.01). Our results indicate that A771726, the active metabolite of leflunomide, inhibited CD147 expression at the protein level and inhibited gelatinolytic activity of MMP-2 and MMP-9 in PMA-differentiated THP-1 cells.

Influence of long-term leflunomide treatment on serum amyloid concentration in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic, inflammatory disease that requires intervention with disease-modifying antirheumatic drugs (DMARDs) to stop disease progression. Leflunomide (LEF) is a DMARD with anti-inflammatory and immunomodulatory properties. As its primary mode of action, LEF reversibly inhibits dihydroorotate dehydrogenase, a key enzyme in de novo biosynthesis of pyrimidine in cells. Serum amyloid A protein (SAA) is elevated in inflammatory states and high SAA levels indicate a risk of developing secondary amyloidosis. The aim of this study was to investigate the effects of long-term LEF treatment on SAA levels and disease activity in a group of RA patients. The study group consisted of 50 consecutive RA patients (43 F, 7 M) treated with leflunomide. All patients had a clinical evaluation and SAA measurements taken at two consecutive visits during months 0, 1, 3, 6 and 12. Mean SAA concentrations decreased significantly in the first months of LEF therapy (up to the 6th month) with a more pronounced effect in patients with higher SAA levels. However, by the 12(th) month of treatment, the mean SAA level did not differ significantly from the SAA level at the start of treatment. At the same time though, other clinical and laboratory parameters of RA activity indicated that the disease activity decreased. Results demonstrated that in patients with active RA LEF therapy provided a significant, long-term reduction of inflammatory activity, as measured by the classic parameters of disease activity. During the treatment, SAA concentrations decreased significantly, followed by a slight increase, in spite of a reduction in other classical indicators of inflammatory response.

Leflunomide in the treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic and highly morbid disease affecting approximately 1% of the world's population. With the advent of disease-modifying antirheumatic drugs, patients are increasingly able to maintain control of their arthritis and prevent joint destruction. However, not all patients respond adequately to any single disease-modifying antirheumatic drug, and many newer parenteral therapies are cost prohibitive. Leflunomide, an inhibitor of pyrimidine biosynthesis, is the first oral disease-modifying antirheumatic drug to have been approved for rheumatoid arthritis in the USA in the last 15 years, and is now widely used in over 70 countries around the world. Leflunomide is efficacious when used as monotherapy or in combination with methotrexate to treat patients with rheumatoid arthritis, and is generally well tolerated. As clinical use increases, new ways to use leflunomide in order to minimize toxicity and maximize efficacy are being explored.

Aberrant reactive oxygen and nitrogen species generation in rheumatoid arthritis (RA): causes and consequences for immune function, cell survival, and therapeutic intervention

The infiltration and persistence of hematopoietic immune cells within the rheumatoid arthritis (RA) joint results in elevated levels of pro-inflammatory cytokines, increased reactive oxygen (ROS) and -nitrogen (RNS) species generation, that feeds a continuous self-perpetuating cycle of inflammation and destruction. Meanwhile, the controlled production of ROS is required for signaling within the normal physiological reaction to perceived "foreign matter" and for effective apoptosis. This review focuses on the signaling pathways responsible for the induction of the normal immune response and the contribution of ROS to this process. Evidence for defects in the ability of immune cells in RA to regulate the generation of ROS and the consequence for their immune function and for RA progression is considered. As the hypercellularity of the rheumatoid joint and the associated persistence of hematopoietic cells within the rheumatoid joint are symptomatic of unresponsiveness to apoptotic stimuli, the role of apoptotic signaling proteins (specifically Bcl-2 family members and the tumor suppressor p53) as regulators of ROS generation and apoptosis are considered, evaluating evidence for their aberrant expression and function in RA. We postulate that ROS generation is required for effective therapeutic intervention.

Multiparameter phospho-flow analysis of lymphocytes in early rheumatoid arthritis: implications for diagnosis and monitoring drug therapy

Background

The precise mechanisms involved in the initiation and progression of rheumatoid arthritis (RA) are not known. Early stages of RA often have non-specific symptoms, delaying diagnosis and therapy. Additionally, there are currently no established means to predict clinical responsiveness to therapy. Immune cell activation is a critical component therefore we examined the cellular activation of peripheral blood mononuclear cells (PBMCs) in the early stages of RA, in order to develop a novel diagnostic modality.

Methods and Findings

PBMCs were isolated from individuals diagnosed with early RA (ERA) (n = 38), longstanding RA (n = 10), osteoarthritis (OA) (n = 19) and from healthy individuals (n = 10). PBMCs were examined for activation of 15 signaling effectors, using phosphorylation status as a measure of activation in immunophenotyped cells, by flow cytometry (phospho-flow). CD3+CD4+, CD3+CD8+ and CD20+ cells isolated from patients with ERA, RA and OA exhibited activation of multiple phospho-epitopes. ERA patient PBMCs showed a bias towards phosphorylation-activation in the CD4+ and CD20+ compartments compared to OA PBMCs, where phospho-activation was primarily observed in CD8+ cells. The ratio of phospho (p)-AKT/p-p38 was significantly elevated in patients with ERA and may have diagnostic potential. The mean fluorescent intensity (MFI) levels for p-AKT and p-H3 in CD4+, CD8+ and CD20+ T cells correlated directly with physician global assessment scores (MDGA) and DAS (disease activity score). Stratification by medications revealed that patients receiving leflunomide, systemic steroids or anti-TNF therapy had significant reductions in phospho-specific activation compared with patients not receiving these therapies. Correlative trends between medication-associated reductions in the levels of phosphorylation of specific signaling effectors and lower disease activity were observed.

Conclusions

Phospho-flow analysis identified phosphorylation-activation of specific signaling effectors in the PB from patients with ERA. Notably, phosphorylation of these signaling effectors did not distinguish ERA from late RA, suggesting that the activation status of discrete cell populations is already established early in disease. However, when the ratio of MFI values for p-AKT and p-p38 is >1.5, there is a high likelihood of having a diagnosis of RA. Our results suggest that longitudinal sampling of patients undergoing therapy may result in phospho-signatures that are predictive of drug responsiveness.

IL-1beta, IL-6, and TNF gene polymorphisms do not affect the treatment outcome of rheumatoid arthritis patients with leflunomide

Leflunomide is an isoxazole derivative that is structurally and functionally unrelated to other known immunomodulatory drugs. Previous studies have revealed that therapy with leflunomide causes decreased production of mediators such as IL-1beta, IL-6, and TNF-alpha, which are involved in inflammatory process. The aim of the present study was to examine whether the polymorphisms in genes IL1B, IL6, and TNF may affect treatment outcomes in RA patients treated with leflunomide. The study was carried out on 129 patients (106 women, 23 men, mean age 52.9 +/- 11.03) diagnosed with RA and treated with leflunomide 20 mg daily. Clinical improvement was evaluated according to the American College of Rheumatology (ACR) 20% and 50% response criteria. There were no statistically significant associations between the studied genotypes and improvement of disease activity parameters. The results of the present study suggest that IL1beta, IL6, and TNF gene polymorphisms are not significant factors influencing the therapy outcome of RA patients with leflunomide.

Preliminary study on the immunologic background of good clinical outcome in rheumatoid arthritis patients after one month therapy with leflunomide

This preliminary study focuses on early peripheral cellular immune changes after 1 month therapy with leflunomide, in 18 patients with severe rheumatoid arthritis, previously treated with methotrexate. A good clinical outcome of disease was documented and we showed that a particular target of short-time leflunomide therapy in rheumatoid arthritis was the peripheral innate immune system (NK cells and the population of granulocytes developing phagocytosis and superoxide anion production when challenged ex vivo with zymosan particles). Meanwhile, the high inter-individual variability of adaptive immunity required data analysis in subgroups of patients. We showed that the abnormal increase of peripheral leukocytes counts, or the decrease towards normal values of the CD4:CD8 lymphocytes ratio, or the inhibition of uridine uptake by ex vivo activated lymphocytes were consistent with a positive clinical evolution, proved by the reduction of tender/swollen joints, morning stiffness duration or acute phase response. We emphasized that significant benefits of short-term leflunomide therapy were associated with functional suppression of peripheral B lymphocytes. Hence, the positive evolution of rheumatoid arthritis patients seemed to be specifically linked to early drug-induced changes of trafficking or uridine metabolism of mononuclear cells.

Hyaluronan suppresses IL-1beta-induced metalloproteinase activity from synovial tissue

Intraarticular injection of hyaluronan (viscosupplementation) is commonly used to treat knee pain from osteoarthritis. The therapeutic benefit might derive from hyaluronan inhibition of the activity of the cytokine-regulated catabolic enzymes that attack joint cartilage (matrix metalloproteinases). We tested the hypothesis that hyaluronan inhibited interleukin-1beta-induced matrix metalloproteinase activity secreted by explants of synovial tissue from patients with osteoarthritis and investigated the mechanism of the effect. Hyaluronan with a molecular mass of 12.8 MDa (number average) antagonized induced metalloproteinase activity in proportion to hyaluronan concentration in the clinically relevant range of 2 to 8 mg/mL. The effect was not attributable solely to molecular mass because 1.2-MDa hyaluronan produced comparable inhibition. Based on measurements involving hyaluronans of different average molecular masses, polydispersity and viscosity were similarly ruled out as primary responsible factors. The effect of hyaluronan on induced metalloproteinase activity was mediated partially by CD44, the principal cell surface receptor for hyaluronan. Hyaluronan inhibited interleukin-1beta-induced metalloproteinase production from osteoarthritic synovial tissue by a process that was not solely dependent on hyaluronan molecular mass but that was partly mediated by hyaluronan binding to CD44. The efficacy of viscosupplementation could be explained if hyaluronan also blocked catabolic enzyme activity in the joint.

Inhibitory effect of mizoribine on matrix metalloproteinase-1 production in synovial fibroblasts and THP-1 macrophages

To investigate the mechanism of antirheumatic action of mizoribine (MZR), we examined the expression of matrix metalloproteinase-1 (MMP-1) and MMP-3 utilizing THP-1 derived macrophage-like cells (THP-1 macrophages) and human synovial fibroblasts (SFs). The cells were respectively stimulated with lipopolysaccharide (LPS) and interleukin-1beta in the presence or absence of MZR in vitro. The concentrations of MMP-1 and MMP-3 in the supernatant were measured by enzyme-linked immunosorbent assay. The secretion of MMP-1 from SFs, as well as THP-1 macrophages, was inhibited by MZR in a dose-dependent manner. Furthermore, a quantitative real-time polymerase chain reaction revealed that MZR decreased the expression of MMP-1 messenger RNA. These findings may be an explanation for the clinical effect of MZR in patients with rheumatoid arthritis.

Prevention of renal ischemia/reperfusion-induced injury in rats by leflunomide

OBJECTIVE

There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of leflunomide, an isoxazole derivative and a unique immunomodulatory agent, in I/R-induced renal injury in rats.

METHODS

Forty female Sprague-Dawley rats were divided equally into four groups: (I) control (only leflunomide 10 mg/kg, intragastrically treated); (II) sham operated (only unilateral nephrectomy); (III) I/R; and (IV) leflunomide (10 mg/kg for two doses prior to experiment) plus I/R groups. In groups III and IV, after unilateral nephrectomy, the rats were subjected to 60 min of left renal pedicle occlusion, followed by 6 h of reperfusion. At the end of the reperfusion period, rats were killed and kidneys and blood were removed. Catalase, myeloperoxidase and xanthine oxidase activities, and malondialdehyde, nitric oxide and protein carbonyl levels were determined in renal tissue. Serum creatinine, blood urea nitrogen and aspartate aminotransferase were measured for the evaluation of renal function. In histopathological examination, renal damage was scored 0-3.

RESULTS

Group III animals demonstrated severe deterioration of renal function, renal morphology and a significant renal oxidative stress. Pretreatment of animals with leflunomide markedly attenuated renal dysfunction, morphological alterations, reduced elevated oxidative stress products levels and restored the depleted renal antioxidant enzyme.

CONCLUSION

The findings imply that oxygen radicals play a causal role in I/R-induced renal injury, and leflunomide exerts renoprotective effects probably by the radical scavenging and antioxidant activities with immunomodulatory effect.

Hepatic damage in biliary-obstructed rats is ameliorated by leflunomide treatment

Cholestasis, or impaired bile flow, occurs in a wide variety of liver diseases and causes hepatic damage by retention and accumulation of toxic hydrophobic bile salts inducing persistent inflammation and oxidative stress. In the present research, we studied the effect of leflunomide, a novel immunosuppressive and anti-inflammatory agent against autoimmune disease, on hepatic damage produced by double ligature of the extrahepatic biliary duct in Wistar Albino rats. Cholestasis was done by double ligature and section of the extrahepatic biliary duct (BDL). Leflunomide was given i.g. 10 mg/kg/day. The severity of cholestasis and hepatic injury was determined by changes in the plasma enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and levels of direct bilirubin. Malondialdehyde (MDA), protein carbonyl (PC), nitric oxide (NO), catalase (CAT) and superoxide dismutase (SOD) were determined to the oxidative status in the liver tissue. Myeloperoxidase (MPO) activity and levels of tissue hydroxyproline (HPR) were determined to neutrophil activation and collagen accumulation, respectively. Further, histological changes were studied. Treatment with leflunomide markedly reduced serum transaminase activities as compared to BDL rats. At the same time leflunomide significantly inhibited increases in liver MDA, PC and NO levels and also attenuated the depletion of CAT and SOD in the liver after bile duct ligation. Similarly, increase in tissue MPO activity and HPR due to BDL was also attenuated by leflunomide treatment. These findings were supported by histopathological findings. These findings suggested that leflunomide can attenuate hepatic damage in extrahepatic cholestasis by prevention of oxidative stress and inflammatory process.

Protective effects of leflunomide against ischemia-reperfusion injury of the rat liver

Hepatic ischemia-reperfusion (I/R) injury may be developed in some conditions, such as trauma, major hepatic resection, hemorrhagic shock or liver transplantation. I/R injury of the liver causes hepatocellular damage that may lead to hepatic failure. A considerable body of evidence indicates that reactive oxygen species (ROS) and inflammation may contribute to hepatocellular injury in liver I/R. Leflunomide is an isoxazole derivative, and a unique immunomodulatory agent. In the present study, we examined the effects of leflunomide on the neutrophil activation with oxidative stress and some antioxidant enzymes in the reperfusion following I/R in the rat liver. Thirty-two rats divided into four groups: group 1 (control); was given leflunomide 10 mg/kg, i.g.; group 2 (SHAM), animals were only laparotomized; group 3 (liver I/R), and group 4 (liver I/R + Leflunomide). In group 4, rats were pretreated with leflunomide (10 mg/kg, i.g.) two doses prior to experiment. In groups 3 and 4, occluding the hepatic pedicel for 60 min induced ischemia and reperfusion was allowed thereafter for 60 min. At the end of the reperfusion period, rats were sacrificed. superoxide dismutase, catalase, nitric oxide, xanthine oxidase, malondialdehyde, protein carbonyl and myeloperoxidase levels were determined in hepatic tissue as well as histological examination with H and E staining. Group 3 animals demonstrated severe deterioration of liver morphology and a significant liver oxidative stress. Pretreatment of animals with leflunomide markedly attenuated morphological alterations and neutrophil activation, reduced elevated oxidative stress products levels and restored the depleted hepatic antioxidant enzyme. The findings imply that ROS play a causal role in I/R-induced hepatic injury, and leflunomide exerts hepatoprotective effects probably by the anti-inflammatory effect with radical scavenging and antioxidant activities.

Anti-inflammatory effects of leflunomide in combination with methotrexate on co-culture of T lymphocytes and synovial macrophages from rheumatoid arthritis patients

OBJECTIVES

To investigate the anti-inflammatory effects of the active leflunomide metabolite A771726 (Lef-M) in combination with methotrexate (MTX) on synovial macrophages (SM) from rheumatoid arthritis (RA) patients co-cultured with an activated T cell line (Jurkat cell line).

METHODS

Pro-inflammatory cytokines (TNFalpha, IL1beta, IL6), adhesion molecule ICAM-1, cyclooxygenase isoenzymes (COX1, COX2), and the nuclear factor kappaB (NF-kappaB) complex were analysed on SM co-cultured with a T cell line, as intracellular protein expression by immunocytochemistry (ICC) and western blot analysis, as extracellular protein expression by ELISA assay, and as mRNA expression by reverse transcriptase-multiplex PCR (RT-MPCR) after treatment with Lef-M (1, 10, 30 micromol/l) alone or in combination with MTX (50 ng/ml).

RESULTS

The most significant intracellular decrease in cytokines was observed by ICC in SM treated with the combination of Lef-M (1, 10, 30 micromol/l) and MTX (50 ng/ml) versus untreated SM (TNFalpha 29%, 37%, 49%, IL1beta 56%, 43%, 50%, and IL6 59%, 62%, 71%, respectively). Furthermore, a significant decrease was confirmed concerning cytokine levels evaluated by ELISA in the medium of SM treated with the combination Lef-M+MTX (TNFalpha 40%, 41%, 44%; IL1beta 10%, 20%, 60%; IL6 37%, 41%, 49%, respectively). Western blot and RT-PCR analysis confirmed these results. Concordant decreased expression was observed for ICAM-1, COX1, COX2, and the NF-kappaB complex after Lef-M+MTX treatment.

CONCLUSIONS

The combination of MTX and Lef-M shows additive inhibitory effects on the production of inflammatory mediators from SM co-cultured with a T cell line. These observations might support the positive results obtained in RA clinical studies by combination therapy.

Neuropathie axonale sévère et léflunomide

INTRODUCTION

Leflunomide is a new drug for the treatment of rheumatoid arthritis. Its mechanism of action is based on lymphocyte inhibition. We report the cases of two patients treated with leflunomide who developed severe sensory-motor axonal polyneuropathy.

OBSERVATION

Two women (61- and 70-year-old) presented with a sensory-motor axonal polyneuropathy beginning 5 months after onset of leflunomide treatment. Etiologic investigations were negative. The symptoms rapidly improved after withdrawing leflunomide.

DISCUSSION

The analysis of drug watch data found twelve patients with leflunomide-related neuropathy. Ten of them were more than 60 years old. The mean delay for onset of neuropathy was 9 months. The neuropathy improved after treatment withdrawal in seven patients.

CONCLUSION

We consider these data strongly suggest that leflunomide is a cause of axonal sensory-motor neuropathy. The prevalence of such adverse events is still unknown.

Curcumin synergistically potentiates the growth-inhibitory and pro-apoptotic effects of celecoxib in osteoarthritis synovial adherent cells

OBJECTIVES

Osteoarthritis (OA) is the Western world's leading cause of disability. Cyclo-oxygenase-2 (COX-2) inhibitors are efficient anti-inflammatory agents commonly used in the treatment of osteoarthritis. However, recent studies have shown that their long-term use may be limited due to cardiovascular toxicity. The anti-inflammatory efficacy of the phytochemical curcumin has been demonstrated in several in vitro and animal models. This study was undertaken to investigate whether curcumin augments the growth-inhibitory and pro-apoptotic effects of celecoxib in OA synovial adherent cells.

METHODS

OA synovial adherent cells were prepared from human synovial tissue collected during total knee replacement surgery. The cells were exposed to different concentrations of celecoxib (0-40 mum), curcumin (0-20 mum) and their combination. Flow cytometric analysis was used to measure the percentage of cells with a subdiploid DNA content, the hallmark of apoptosis. COX-2 activity was assessed by measuring production of prostaglandin E(2) by enzyme-linked immunoassay.

RESULTS

A synergistic effect was observed in inhibition of cell growth when the cells were exposed to various concentrations of celecoxib combined with curcumin. The inhibitory effect of the combination on cell growth was associated with an increased induction of apoptosis. The synergistic effect was mediated through a mechanism that involves inhibition of COX-2 activity.

CONCLUSIONS

This effect may enable the use of celecoxib at lower and safer concentrations, and may pave the way for a novel combination treatment in osteoarthritis and other rheumatological disorders.

Synovial proinflammatory cytokines and their correlation with matrix metalloproteinase-3 expression in Behçet's disease. Does interleukin-1beta play a major role in Behçet's synovitis?

The objective of this study has been the well established fact that proinflammatory cytokines and metalloproteinases play a crucial role in the pathogenesis of chronic arthritis as well as the development of pannus, with the eventual erosive changes. Among the proinflammatory cytokines, interleukin-18 (IL-18) has been shown to contribute to the pathogenesis of chronic synovitis by increasing the secretion of interleukin-1beta (IL-1beta) and the tumor necrosis factor-alpha (TNF-alpha) and also stimulating angiogenesis. The aim of this study is to investigate the synovial IL-18, IL-1beta, TNF-alpha and matrix metalloproteinase-3 (MMP-3) levels in patients with Behçet's disease (BD), and compare them with the levels of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). 30 patients with BD, 20 with RA, and 20 with OA were included in the study. The synovial levels of IL-18, IL-1beta, TNF-alpha and MMP-3 were detected using the two-step sandwich ELISA method. The synovial IL-18, TNF-alpha and MMP-3 levels were significantly higher in RA patients than patients with BD (P=0.004, 0.019, 0.025, respectively) and with OA (P=0.004, 0.045, 0.032, respectively). There were no differences, with respect to the cytokine levels, when patients with BD were compared with those with OA. Patients with RA and BD had higher IL-1beta levels than patients with OA (P=0.017, 0.013, respectively). However, no such difference was found for IL-1beta between BD and RA patients. Among patients with RA, positive correlations were found between TNF-alpha and MMP-3 (r=0.683, P=0.001). Our results showed that MMP-3 and proinflammatory cytokines, except IL-1beta, were expressed in relatively small quantities in Behçet's synovitis. Detection of the lower levels of these cytokines and metalloproteinases might explain the non-erosive character of Behçet's arthritis. We suggest that IL-1beta may be involved in the pathogenesis of Behçet's synovitis.

Leflunomide reduces nitric oxide production in patients with active rheumatoid arthritis

OBJECTIVES

Leflunomide is an immunomodulatory agent that was recently approved for the treatment of rheumatoid arthritis (RA). The mechanism of action is not fully understood. Nitric oxide (NO) plays an important role in the pathogenesis of RA. Leflunomide has been shown to cause cell specific inhibition of inducible nitric oxide synthase (iNOS) activation in animal models. We carried out this study to determine if there was alteration in NO production in patients with RA.

METHODS

An 8-week open label study was carried out on patients with adult onset active RA. We measured levels of nitrite and citrulline spectrophotometrically as surrogate markers of NO production. Within-patient serum levels of nitrite and citrulline were compared with leflunomide therapy at three points of time (at 0, 4 and 8 weeks of therapy).

RESULTS

Thirty-three patients with active RA were enrolled for this study. These patients were a subset of 63 individuals who are studied for clinical efficacy of leflunomide. Three patients were lost to follow-up. Median nitrite levels were 817.2 (nmol/ml) at the start of therapy and this declined to 440.9 nmol/ml and 301.1 nmol/ml at 4 and 8 weeks of therapy. Median citrulline levels were 649.3 nmol/ml at the start of the study, which declined to 549.2 nmol/ml and 485.4 nmol/ml at 4 and 8 weeks, respectively. Statistically significant decrease in median values for serum nitrite and citrulline levels was documented after 4 weeks of leflunomide therapy (p<0.01), which was sustained at 8 weeks (p<0.01), although there was no further fall between 4 and 8 weeks (p>0.1).

CONCLUSIONS

Leflunomide inhibits nitric oxide production in patients with active RA. Inhibition of NO synthesis may be one of the mechanisms responsible for the immunomodulatory activity of leflunomide.

Suppressive effect of leflunomide metabolite (A77 1726) on metalloproteinase production in IL-1beta stimulated rheumatoid synovial fibroblasts

Leflunomide, an isoxazol derivative structurally unrelated to other immunomodulatory drugs, has proven to be efficacious in the treatment of rheumatoid arthritis (RA). This study was conducted to elucidate the mechanism by which leflunomide mediated antirheumatic effects. We investigated the effects of A77 1726, leflunomide's active metabolite, on mitogen-activated protein kinase (MAPK) activation in IL-1beta-stimulated rheumatoid synovial fibroblasts. The effects of A77 1726 on the secretion of matrix metalloproteinases (MMPs) from rheumatoid synovial fibroblasts were also examined. A77 1726 partially suppressed IL-1beta-induced ERK1/2 and p38 kinase activation. In contrast, A77 1726 efficiently suppressed IL-1beta-stimulated JNK1/2 kinase activation. Although no suppressive effect was demonstrated on MMP-2, A77 1726 markedly inhibited MMP-1, 3, and 13 secretions from IL-1beta-stimulated rheumatoid synovial fibroblasts. Tissue inhibitor of metalloproteinases-1 (TIMP-1) was constitutively produced from rheumatoid synovial fibroblasts and the suppressive effects of A77 1726 on TIMP-1 production were minimal. Our results suggest that the suppression of the MAPK signalling pathway and MMP synthesis in rheumatoid synovial fibroblasts is a possible mechanism for the inhibitory activity of leflunomide against rheumatoid arthritis.

Increased intercellular communication through gap junctions may contribute to progression of osteoarthritis

Our aim was to support the hypothesis of a specific association between gap junctions in synovial tissue and the presence of osteoarthritis, as evidenced by differences between osteoarthritis and non-osteoarthritis synovia in the number of gap junctions, the amount of gap-junction protein, and the amount of enzymatic activity produced through a pathway mediated by gap-junction intercellular communication. An average of 4.41 gap junctions were found per 100 cells counted in the osteoarthritis synovia, compared with 1.00 in the controls. The amount of the gap-junction protein connexin 43 in synovial lining cells was approximately 50% greater in patients with osteoarthritis. Synovial lining cells from patients with osteoarthritis produced matrix metalloproteinases constitutively and, at higher levels, in response to stimulation by interleukin-1 beta. In both cases, intercellular communication through gap junctions was shown to be critical to the ability of the cells to secrete matrix metalloproteinases. Overall, the results indicated that gap junctions between synovial lining cells were altered significantly in patients with osteoarthritis, as a consequence of the disease process or as part of the causal chain. In either case, gap junctions seem to be a rational therapeutic target.

The active metabolite of leflunomide, A77 1726, increases the production of IL-1 receptor antagonist in human synovial fibroblasts and articular chondrocytes

Leflunomide is an immunomodulatory agent used for the treatment of rheumatoid arthritis. In this study, we investigated the effect of A77 1726 – the active metabolite of leflunomide – on the production of IL-1 receptor antagonist (IL-1Ra) by human synovial fibroblasts and articular chondrocytes. Cells were incubated with A77 1726 alone or in combination with proinflammatory cytokines. IL-1Ra production was determined by ELISA. A77 1726 alone had no effect, but in the presence of IL-1β or tumour necrosis factor-α it markedly enhanced the secretion of IL-1Ra in synovial fibroblasts and chondrocytes. The effect of A77 1726 was greatest at 100 μmol/l. In synovial fibroblasts and de-differentiated chondrocytes, A77 1726 also increased IL-1β-induced IL-1Ra production in cell lysates. Freshly isolated chondrocytes contained no significant amounts of intracellular IL-1Ra. A77 1726 is a known inhibitor of pyrimidine synthesis and cyclo-oxygenase (COX)-2 activity. Addition of exogenous uridine did not significantly modify the effect of A77 1726 on IL-1Ra production, suggesting that it was not mediated by inhibition of pyrimidine synthesis. Indomethacin increased IL-1β-induced IL-1Ra secretion in synovial fibroblasts and de-differentiated chondrocytes, suggesting that inhibition of COX-2 may indeed enhance IL-1β-induced IL-1Ra production. However, the stimulatory effect of indomethacin was consistently less effective than that of A77 1726. A77 1726 increases IL-1Ra production by synovial fibroblasts and chondrocytes in the presence of proinflammatory cytokines, and thus it may possess chondroprotective effects. The effect of A77 1726 may be partially mediated by inhibition of COX-2, but other mechanisms likely concur to stimulate IL-1Ra production.