Identification of TGFß signatures in six murine models mimicking different osteoarthritis clinical phenotypes.

OBJECTIVE: TGFß is a key player in cartilage homeostasis and OA pathology. However, few data are available on the role of TGFß signalling in the different OA phenotypes. Here, we analysed the TGFß pathway by transcriptomic analysis in six mouse models of OA. METHOD: We have brought together seven expert laboratories in OA pathophysiology and, used inter-laboratories standard operating procedures and quality controls to increase experimental reproducibility and decrease bias. As none of the available OA models covers the complexity and heterogeneity of the human disease, we used six different murine models of knee OA: from post-traumatic/mechanical models (meniscectomy (MNX), MNX and hypergravity (HG-MNX), MNX and high fat diet (HF-MNX), MNX and seipin knock-out (SP-MNX)) to aging-related OA and inflammatory OA (collagenase-induced OA (CIOA)). Four controls (MNX-sham, young, SP-sham, CIOA-sham) were added. OsteoArthritis Research Society International (OARSI)-based scoring of femoral condyles and ribonucleic acid (RNA) extraction from tibial plateau samples were done by single operators as well as the transcriptomic analysis of the TGFß family pathway by Custom TaqMan® Array Microfluidic Cards. RESULTS: The transcriptomic analysis revealed specific gene signatures in each of the six models; however, no gene was deregulated in all six OA models. Of interest, we found that the combinatorial Gdf5-Cd36-Ltbp4 signature might discriminate distinct subgroups of OA: Cd36 upregulation is a hallmark of MNX-related OA while Gdf5 and Ltbp4 upregulation is related to MNX-induced OA and CIOA. CONCLUSION: These findings stress the OA animal model heterogeneity and the need of caution when extrapolating results from one model to another.

Fibroblast Growth Factor 23 drives MMP13 expression in human osteoarthritic chondrocytes in a Klotho-independent manner.

OBJECTIVE: Fibroblast Growth Factor 23 (FGF23) may represent an attractive candidate that could participate to the osteoarthritic (OA)-induced phenotype switch of chondrocytes. To address this hypothesis, we investigated the expression of FGF23, its receptors (FGFRs) and co-receptor (Klotho) in human cartilage and studied the effects of rhFGF23 on OA chondrocytes. METHOD: Gene expression or protein levels were analysed by RT-PCR and immunohistochemistry. Collagenase 3 (MMP13) activity was measured by a fluorescent assay. MAPK signalling pathways were investigated by phosphoprotein array, immunoblotting and the use of selective inhibitors. RNA silencing was performed to confirm the respective contribution of FGFR1 and Klotho. RESULTS: We showed that the expression of FGF23, FGFR1 and Klotho was up-regulated at both mRNA and protein levels in OA chondrocytes when compared to healthy ones. These overexpressions were markedly elevated in the damaged regions of OA cartilage. When stimulated with rhFGF23, OA chondrocytes displayed an extended expression of FGF23 and of markers of hypertrophy such as MMP13, COL10A1, and VEGF. We demonstrated that FGF23 auto-stimulation was both FGFR1-and Klotho-dependent, whereas the expression of markers of hypertrophy was mainly dependent on FGFR1 alone. Finally, we showed that FGF23-induced MMP13 expression was strongly regulated by the MEK/ERK cascade and to a lesser extent, by the PI-3K/AKT pathway. CONCLUSION: These results demonstrate that FGF23 sustains differentiation of OA chondrocytes in a Klotho-independent manner.

Association between adiponectin and cartilage degradation in human osteoarthritis.

OBJECTIVE: Conflicting findings raise questions about the role of adiponectin in osteoarthritis (OA). The current study aimed to investigate in OA patients the association between the production of adiponectin and the grade of cartilage destruction, and to provide functional evidence for a potential role of adiponectin in OA. DESIGN: The expression of adiponectin was examined by immunohistochemistry in cartilage obtained from healthy individuals (n = 2; ages 56 and 41 years; 1 male and 1 female) and OA patients (n = 11; ages 64-79 years; 2 male and 9 female). The association between its production in chondrocytes and the grade of cartilage destruction was established on full-depth cartilage biopsies. The functional activity of adiponectin in OA cartilage was determined from the relation between the expression of adiponectin, its receptor, cartilage-specific components and factors involved in matrix degradation, and from the chondrocyte response to the full-length or the globular form of adiponectin. RESULTS: Adiponectin was not detected in healthy cartilage. Conversely, the adipokine was up-regulated in damaged tissue, but no strong association with the grade of cartilage destruction was found. We showed a positive correlation between adiponectin and mPGES or MMP-13 while AdipoR1 was related to the expression of type 2 collagen, aggrecan and Sox9. The full-length form of adiponectin but not the globular isoform, stimulated the production of PGE2 and MMP-13 activity in cultured human chondrocytes. CONCLUSIONS: The elevated level of adiponectin found in chondrocytes from OA patients might contribute to matrix remodelling during OA, the full-length isoform being the single active form.

Evidence for species differences in the regulation of MMPs by all-trans retinoic acid in cytokine-stimulated chondrocytes.

In inflammatory conditions, chondrocytes produce large amounts of matrix metalloproteases (MMP) and nitric oxide (NO) thought to contribute to joint degradation. We tested the ability of all-trans retinoic acid (ATRA, a retinoic acid receptor (RAR) agonist) to modulate these inflammatory genes in chondrocytes from humans or rats, chosen as representative of animal models of arthritis. All RAR subtypes and RXR-alpha or -beta were expressed at the mRNA level in both species, although IL-1beta (10 ng/ml) inhibited RAR subtypes more markedly in rat than in human cells. ATRA (300 or 1000 nM) inhibited IL-1-induced expression of iNOS and nitrites level in both species, although the NO pathway was induced maximally in rat cells. ATRA displayed controversial effects on MMPs between rat and human chondrocytes, especially for MMP-9 expression. The effects of ATRA were irrelevant to the nuclear translocation of AP-1. The present data underlines that retinoids have a species-dependent impact on IL-1-induced responses in chondrocytes, suggesting that extrapolation of their pharmacological properties from animal cells has a poor relevance to clinical situation.

Modulatory effect of rhein on IL-1alpha-induced responses in human chondrocytes: a comparative study between antibody microarrays and specific ELISAs.

The present work aimed to take advantage of the screening capacity of protein arrays to search for additional targets of rhein in interleukin (IL)-1-stimulated chondrocytes. Primary cultures of chondrocytes from osteoarthritic (OA) patients were stimulated for 24 and 48 h with 1 ng/ml of IL-1alpha, in the presence or absence of 10(-5) M of rhein. Culture supernatants were analyzed with arrays membranes consisting of 120 antibodies directed against cytokines, chemokines, and angiogenic or growth factors and were controlled for 8 proteins by specific immuno-enzymatic assays (ELISA). Protein arrays showed that several CC or CXC chemokines, the growth factor GM-CSF, the cytokines IL-6, IL-7 and IL-10 (but unexpectedly not IL-1beta or TNFalpha) and the adhesion molecule ICAM-1 were induced maximally by IL-1alpha. In IL-1-stimulated chondrocytes, rhein reduced slightly the production of MCP-1 and increased those of IL-1Ra, of the cytokine receptors sgp130, IL-6R, sTNFR I and R II, but also of some chemokines or ICAM-1. Specific ELISAs confirmed the effect of rhein on MCP-1, IL-1Ra, sgp130, IL-6R and sTNFR II but was discrepant for GROalpha and were always more sensitive than protein arrays to detect IL-1 effects such as IL-1Ra and TNFalpha release. The present data show that rhein modulated some IL-1-induced responses contributing possibly to its chondroprotective (IL-1Ra, MCP-1) or cytokine modifying (sTNFR II, sgp130) properties, but that protein arrays were poorly sensitive to check for IL-1- and/or rhein-induced changes.

Review article: moving towards common therapeutic goals in Crohn's disease and rheumatoid arthritis.

BACKGROUND: Crohn's disease (CD) and rheumatoid arthritis are chronic, progressive and disabling conditions that frequently lead to structural tissue damage. Based on strategies originally developed for rheumatoid arthritis, the treatment goal for CD has recently moved from exclusively controlling symptoms to both clinical remission and complete mucosal healing (deep remission), with the final aim of preventing bowel damage and disability. AIM: To review the similarities and differences in treatment goals between CD and rheumatoid arthritis. METHODS: This review examined manuscripts from 1982 to 2016 that discussed and/or proposed therapeutic goals with their supportive evidence in CD and rheumatoid arthritis. RESULTS: Proposed therapeutic strategies to improve outcomes in both rheumatoid arthritis and CD include: (i) evaluation of musculoskeletal or organ damage and disability, (ii) tight control, (iii) treat-to-target, (iv) early intervention and (v) disease modification. In contrast to rheumatoid arthritis, there is a paucity of disease-modification trials in CD. CONCLUSIONS: Novel therapeutic strategies in CD based on tight control of objective signs of inflammation are expected to change disease course and patients' lives by halting progression or, ideally, preventing the occurrence of bowel damage. Most of these strategies require validation in prospective studies, whereas several disease-modification trials have addressed these issues in rheumatoid arthritis over the last decade. The recent approval of new drugs in CD such as vedolizumab and ustekinumab should facilitate initiation of disease-modification trials in CD in the near future.

Elevated hepatocyte growth factor levels in osteoarthritis osteoblasts contribute to their altered response to bone morphogenetic protein-2 and reduced mineralization capacity.

PURPOSE: Clinical and in vitro studies suggest that subchondral bone sclerosis due to abnormal osteoblasts is involved in the progression of osteoarthritis (OA). Human osteoblasts isolated from sclerotic subchondral OA bone tissue show an altered phenotype, a decreased canonical Wnt/ß-catenin pathway, and a reduced mineralization in vitro as well as in vivo. These alterations were linked with an abnormal response to BMP-2. OA osteoblasts release factors such as the hepatocyte growth factor (HGF) that contribute to cartilage loss whereas chondrocytes do not express HGF. HGF can stimulate BMP-2 expression in human osteoblasts, however, the role of HGF and its effect in OA osteoblasts remains unknown. Here we investigated whether elevated endogenous HGF levels in OA osteoblasts are responsible for their altered response to BMP-2. METHODS: We prepared primary human subchondral osteoblasts using the sclerotic medial portion of the tibial plateaus of OA patients undergoing total knee arthroplasty, or from tibial plateaus of normal individuals obtained at autopsy. The expression of HGF was evaluated by qRT-PCR and the protein production by western blot analysis. HGF expression was reduced with siRNA technique whereas its activity was inhibited using the selective inhibitor PHA665752. Alkaline phosphatase activity (ALPase) and osteocalcin release were measured by substrate hydrolysis and EIA respectively. Canonical Wnt/ß-catenin signaling (cWnt) was evaluated both by target gene expression using the TOPflash TCF/lef luciferase reporter assay and western blot analysis of ß-catenin levels in response to Wnt3a stimulation. Mineralization in response to BMP-2 was evaluated by alizarin red staining. RESULTS: The expression of HGF was increased in OA osteoblasts compared to normal osteoblasts and was maintained during their in vitro differentiation. OA osteoblasts released more HGF than normal osteoblasts as assessed by western blot analysis. HGF stimulated the expression of TGF-ß1. BMP-2 dose-dependently (1 to 100 ng/ml) stimulated both ALPase and osteocalcin in normal osteoblasts whereas, it inhibited them in OA osteoblasts. HGF-siRNA treatments reversed this response in OA osteoblasts and restored the BMP-2 response. cWnt is reduced in OA osteoblasts compared to normal, and HGF-siRNA treatments increased cWnt in OA osteoblasts almost to normal. Smad1/5/8 phosphorylation in response to BMP-2, which is reduced in OA osteoblasts, was corrected when these cells were treated with PHA665752. The BMP-2-dependent mineralization of OA osteoblasts, which is also reduced compared to normal, was only partially restored by PHA665752 treatment whereas 28 days treatment with HGF reduced the mineralization of normal osteoblasts. CONCLUSION: OA osteoblasts expressed more HGF than normal osteoblasts. Increased endogenous HGF production in OA osteoblasts stimulated the expression of TGF-ß1 and reduced their response to BMP-2. Inhibiting HGF expression or HGF signaling restored the response to BMP-2 and Smad1/5/8 signaling. In addition, decreased HGF signaling partly corrects the abnormal mineralization of OA osteoblasts while increased HGF prevents the normal mineralization of normal osteoblasts. In summary, we hypothesize that sustained elevated HGF levels in OA osteoblasts drive their abnormal phenotype and is implicated in OA pathophysiology.

Articular diffusion of meloxicam after a single oral dose: relationship to cyclo-oxygenase inhibition in synovial cells.

OBJECTIVE: To investigate the distribution of meloxicam in the human knee joint and to compare it with the inhibition of cyclo-oxygenase (COX) activity in synovial cells. DESIGN: Prospective pharmacokinetic study and in vitro laboratory investigation. PATIENTS AND PARTICIPANTS: 42 male and female patients aged 26 to 85 years hospitalised for rheumatic disease and requiring a diagnostic and/or therapeutic knee puncture. METHODS: After a single oral dose of meloxicam 15mg, synovial fluid and blood samples were collected once per patient at various intervals after administration. Meloxicam concentrations were determined by a validated high performance liquid chromatography assay, protein binding by equilibrium dialysis, and pharmacokinetic parameters were calculated by noncompartmental analysis from the mean drug concentration-time profiles. The inhibitory effect of meloxicam on COX activity was investigated separately in unstimulated or interleukin-1beta-stimulated human synovial cells from osteoarthritic patients. RESULTS: Meloxicam was found in synovial fluid at the earliest sampling time (1 hour). Peak concentrations were reached approximately 6 hours postdose in both plasma (842 microg/L) and synovial fluid (320 microg/L). A plateau was observed after the distribution phase (6 hours), corresponding to a constant ratio of drug concentration between synovial fluid and plasma of about 0.47. This ratio was higher in patients with acute inflammation (0.58) than in those with no inflammation (0.38). Meloxicam was extensively bound to protein, mainly to serum albumin. The area under the drug concentration-time curve (AUC) in plasma was more than 2.5 times that in synovial fluid. The AUC for free meloxicam was similar in plasma and synovial fluid. The 50% inhibitory concentrations (IC50) for basal and stimulated COX activity in human synovial cells were 33.7 nmol/L (11.8 microg/L) and 2.0 nmol/L (0.70 microg/L), respectively. The free concentration of meloxicam in synovial fluid was higher than the IC50 for stimulated COX activity from 6 to 36 hours postdose. CONCLUSION: On the basis of free synovial concentrations and the IC50 for stimulated COX activity, meloxicam is expected to have a long duration of action. Inhibition of COX activity is expected to be more marked in inflamed synovium compared with non-inflamed synovium.

Modulation of IL-1-induced cartilage injury by NO synthase inhibitors: a comparative study with rat chondrocytes and cartilage entities.

Nitric oxide (NO) is produced in diseased joints and may be a key mediator of IL-1 effects on cartilage. Therefore, we compared the potency of new [aminoguanidine (AG), S-methylisothiourea (SMT), S-aminoethylisothiourea (AETU)] and classical [Nomega-monomethyl-L-arginine (L-NMMA), Nomega-nitro-L-arginine methyl ester (L-NAME)] NO synthase (NOS) inhibitors on the inhibitory effect of recombinant human interleukin-1beta (rhIL-1beta) on rat cartilage anabolism. Three different culture systems were used: (1) isolated chondrocytes encapsulated in alginate beads; (2) patellae and (3) femoral head caps. Chondrocyte beads and cartilage entities were incubated in vitro for 48 h in the presence of rhIL-1beta with a daily change of incubation medium to obtain optimal responses on proteoglycan synthesis and NO production. Proteoglycan synthesis was assessed by incorporation of radiolabelled sodium sulphate [Na2(35)SO4] and NO production by cumulated nitrite release during the period of study. Chondrocytes and patellae, as well as femoral head caps, responded concentration-dependently to IL-1beta challenge (0 to 250 U ml(-1) and 0 to 15 U ml(-1) respectively) by a large increase in nitrite level and a marked suppression of proteoglycan synthesis. Above these concentrations of IL-1beta (2500 U ml(-1) and 30 U ml(-1) respectively), proteoglycan synthesis plateaued whereas nitrite release still increased thus suggesting different concentration-response curves. When studying the effect of NOS inhibitors (1 to 1000 microM) on NO production by cartilage cells stimulated with IL-1beta (25 U ml(-1) or 5 U ml(-1)), we observed that: (i) their ability to reduce nitrite level decreased from chondrocytes to cartilage samples, except for L-NMMA and AETU; (ii) they could be roughly classified in the following rank order of potency: AETU > L-NMMA > or = SMT > or = AG > or = L-NAME and (iii) AETU was cytotoxic when used in the millimolar range. When studying the effect of NOS inhibitors on proteoglycan synthesis by cartilage cells treated with IL-1beta, we observed that: (i) they had more marked effects on proteoglycan synthesis in chondrocytes than in cartilage samples; (ii) they could be roughly classified in the following rank order of potency: L-NAME > or = L-NMMA > > AG > SMT > > AETU and (iii) potentiation of the IL-1 effect by AETU was consistent with cytotoxicity in the millimolar range. D-isomers of L-arginine analog inhibitors (1000 microM) were unable to correct nitrite levels or proteoglycan synthesis in IL-1beta treated cells. L-arginine (5000 microM) tended to reverse the correcting effect of L-NMMA (1000 microM) on proteoglycan synthesis, thus suggesting a NO-related chondroprotective effect. However, data with L-NAME and SMT argued against a general inverse relationship between nitrite level and proteoglycan synthesis. Dexamethasone (0.1 to 100 microM) (i) failed to inhibit NO production in femoral head caps and chondrocytes beads whilst reducing it in patellae (50%) and (ii) did not affect or worsened the inhibitory effect of IL-1beta on proteoglycan synthesis. Such results suggested a corticosteroid-resistance of rat chondrocyte iNOS. Data from patellae supported a possible contribution of subchondral bone in NO production. In conclusion, our results suggest that (i) NO may account only partially for the suppressive effects of IL-1beta on proteoglycan synthesis, particularly in cartilage samples; (ii) the chondroprotective potency of NOS inhibitors can not be extrapolated from their effects on NO production by joint-derived cells and (iii) L-arginine analog inhibitors are more promising than S-substituted isothioureas for putative therapeutical uses.

Cyclo-oxygenase isoenzymes. How recent findings affect thinking about nonsteroidal anti-inflammatory drugs.

The discovery of at least 2 cyclo-oxygenase (COX) isoenzymes, referred to as COX-1 and COX-2, has updated our knowledge of nonsteroidal anti-inflammatory drugs (NSAIDs). This has lead investigators to reconsider what can be awaited from this class of drugs. The 2 COX isoenzymes share structural and enzymatic similarities, but are specifically regulated at the molecular level and may be distinguished apart in their functions, although some physiological overlap between them does occur. The major goal in developing selective COX inhibitors is to improve NSAID tolerability. Classic NSAIDs preferentially inhibit COX-1 in vitro, but it appears hazardous to judge their gastrointestinal (GI) safety profile from these data. New compounds with a high selectivity for COX-2, especially those that are non-acidic, may be better tolerated in the GI tract. While these compounds also might have a potential use in various diseases such as colorectal cancer and neurodegenerative diseases of the Alzheimer type, the possible appearance of adverse effects, perhaps renally-related, must be taken into consideration. Finally, well-designed large clinical trials are required to adequately estimate both the promising therapeutic advantages that may be offered by highly selective NSAIDs, and the potential drawbacks that may be inherent with prolonged COX-2 inhibition.

Evaluation of the effect of three surface treatments on the biocompatibility of 316L stainless steel using human differentiated cells.

AISI 316L stainless steel (SS) is widely used in orthopaedic implantology, although biological complications may result from its insufficient mechanical and tribological properties. In order to improve the wear and corrosion resistance as well as the hardness of 316L SS, three surface treatments, derived from those applied in mechanical engineering industries, were investigated: (1) glow discharge nitrogen implantation, (2) carbon-doped stainless steel coating sputtering and (3) low temperature plasma nitriding. Surface characterization according to the different heat treatments showed that corrosion and wear resistance were strongly improved, especially by ion implantation or carbon-doped SS coating sputtering. In the same way, microhardness was significantly increased after the three treatments. The effect of such treatments on the biocompatibility of 316L SS was studied with human osteoblast and fibroblast cultures. Basic and specific features of the cells showed that ion-implanted and carbon-doped stainless steels were biocompatible, whereas dramatic cellular reactions were noted when contacted with nitrided stainless steel. A hypothesis is given to explain this observation but further experiments are needed to optimize the nitriding process. Nitrogen implantation and carbon-doped layer deposition could be efficient means for improving the physical properties of stainless steel without affecting its biocompatibility. Such surface treatments may have relevance for increasing the life time of 316L biomedical devices.

Cytocompatibility of Ti-6Al-4V and Ti-5Al-2.5Fe alloys according to three surface treatments, using human fibroblasts and osteoblasts.

Titanium alloys are well known for their superior mechanical properties as well as for their good biocompatibility, making them desirable as surgical implant materials. However, these alloys have been proven to behave poorly in friction since wear particles were often detected in tissues and organs associated with titanium implants. In this paper, three surface treatments were investigated in order to improve the wear resistance and the hardness of Ti-6Al-4V and Ti-5Al-2.5Fe: (a) glow discharge nitrogen implantation (10(17) atoms cm-2), (b) plasma nitriding by plasma diffusion treatment (PDT) and (c) deposition of TiN layer by plasma-assisted chemical vapour deposition (PACVD) additionally to PDT. Surface characterization after the different treatments showed considerable improvement in surface hardness, especially after the two nitriding processes. Moreover, the good corrosion resistance of untreated alloys was maintained. A cell culture model using human cells was chosen to study the effect of such treatments on the cytocompatibility of these materials. The results showed that Ti-5Al-2.5Fe alloy was as cytocompatible as the Ti-6Al-4V alloy and the same surface treatment led to identical biological consequences on both alloys. Nitrogen implantation did not modify at all the cellular behaviour observed on untreated samples. After the two nitriding treatments, cell proliferation and viability appeared to be significantly reduced and the scanning electron microscopy study revealed somewhat irregular surface states. However, osteoblast phenotype expression and protein synthesis capacity were not affected. PDT and PACVD may be interesting alternatives to the physical vapour deposition technique.

Pro- and anti-inflammatory properties of human recombinant IL-1 beta during experimental arthritis in rats: 1. Dependence on dose and severity threshold.

The effects of human recombinant interleukin-1 beta (HrIL-1 beta) were investigated in arthritic rats sensitized with type II collagen (CII) and muramyl dipeptide (MDP). When administered subcutaneously (sc) daily during established arthritis, low (0.02 micrograms) and medium (0.2 micrograms) HrIL-1 beta doses exerted paradoxical beneficial properties on paws with moderate and severe inflammation, respectively. In contrast, the highest dose (2 micrograms) had a pejorative effect on developing arthritis. In addition, HrIL-1 beta attenuated paw volume and deterioration of the joints as assessed radiologically. Hence, paw inflammation response to IL-1 exposure depended on the dosage and the severity of previous arthritis prior to the IL-1 challenge. Some of these paradoxical activities may be due to the capacity of IL-1 to induce its own inhibitors or feedback loops thus counterbalancing its phlogistic properties.

Pro- and anti-inflammatory properties of human recombinant IL-1 beta during experimental arthritis in rats: 2. Period-dependent effect.

The systemic effects of human recombinant Interleukin-1 beta (HrIL-1 beta) on hindpaw edema were determined in arthritis induced by human native type II collagen (CII) with muramyl dipeptide (MDP) both injected on day 0. Daily treatment with HrIL-1 beta (0.2 microgram sc) pretreatment, from D-1 (the day before MDP and CII were injected) to D3 significantly delayed the secondary inflammation in the uninjected left hindpaw, whereas the same treatment from D6 to D10 at the end of the "primary" inflammation, enhanced the volume of the left hindpaw. Treatment from D13 to D17 did not affect the "secondary" edema in the left hindpaw. Thus, HrIL 1 beta administration produces pro- or anti-inflammatory effects on a developing polyarthritis depending on when treatment is started and is most effective as an anti-inflammatory molecule when started at the peak of the the inflammatory reaction, as previously described. In view of these early findings, we have compared the effect of adding HrIL-1 beta along with MDP in the sensitization procedure on the time-course of CII-induced arthritis. No adjuvant effect of HrIL-1 beta was observed. On the contrary, HrIL-1 beta significantly decreased the signs of inflammation in the injected hindpaw during the secondary inflammation. In addition, the immune response to type II collagen was less in the group receiving HrIL-1 beta, maybe because of nonspecific increase of antigen clearance. On the other hand, the MDP sensitization procedure enhanced the incidence of CII arthritis and significantly worsened the clinical parameters in both primary and secondary inflammations.

Assay of circulating hyaluronic acid in the rat: study of diurnal variation and effect of anesthesia.

Serum hyaluronic acid (HA) may provide a good marker for the severity of joint disease in the rat since a positive correlation was observed in experimental models of arthritis. However, little is known about its physiological variation in rats. In the present work, we do not find any circadian rhythm of HA in healthy Sprague-Dawley rats in contrast to that observed in humans, whose serum levels vary during daytime. Furthermore, the influence of blood sampling conditions on HA concentrations was evaluated in conscious animals and by using different anesthetics. The greater reproducibility for the assay of HA is observed with the intracardiac puncture under ether inhalation. Blood sample collection in the absence of anesthesia leads to a significant increase in serum levels of HA, which could be attributed partly to enhanced joint movements generated by psychological stress.

The role of 3D-microscopy in the study of chondrocyte-matrix interaction (alginate bead or sponge, rat femoral head cap, human osteoarthritic cartilage) and pharmacological application.

The potentialities of a new non-invasive optical scanning microscopy technique were evaluated through 3D analysis of chondrocyte-matrix interactions. Five different 2D or 3D culture systems were used: (1) MonoLayer (ML) of human chondrosarcoma cell line; (2) rat or human chondrocytes encapsulated in Alginate Bead (AB); (3) human chondrocytes encapsulated in Alginate Sponge (AS); (4) Rat Femoral Head Cap (RFHC); (5) slices of knee human Osteoarthritic Cartilage (HOAC). Chondrocytes ML, AB, RFHC were incubated for 24 h in vitro in the presence of recombinant human interleukin1-beta (rhIL1-beta) and the effects on cytoskeleton organisation (F-actin filament), Focal Adhesion Kinase (FAK) expression (tyrosine kinase), collagenase B expression (metalloprotease) were studied. Furthermore, the production of intracellular IL1-beta by LPS- or rhIL1-beta-stimulated chondrocytes was shown to be partly suppressed by rhein (active metabolite of diacerhein) in all culture systems. This high resolution light microscopy gave complementary information that could be important for a better understanding of the interaction of chondrocytes with the extracellular matrix in a variety of culture devices.

[Non-steroidal anti-inflammatory agents with selective inhibitory activity on cyclooxygenase-2. Interest and future prospects]. / Les anti-inflammatoires non stéroïdiens inhibiteurs sélectifs de la cyclooxygénase. 2. Intérêt et perspectives.

INTRODUCTION: Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the production of primary prostanoids by blocking the access of arachidonic acid to the active site of the cyclooxygenases (COXs). Because the prostanoids produced by COX-1 appear to play a physiological role (protection of the gastric mucosa, platelet aggregation, vascular homeostasis, maintenance of renal sodium-water balance) while those produced by COX-2 seem mainly to intervene in the inflammatory response and in certain processes associated with cell proliferation, the hypothesis has been put forward that the NSAIDs that are selective COX-2 inhibitors should theoretically be capable of maintaining NSAID therapeutic properties but also have fewer adverse side effects due to the maintenance of prostaglandin production at normal physiological levels. CURRENT KNOWLEDGE AND KEY POINTS: The hypothesis of COX isoenzyme selectivity has led to a proposed classification for COX inhibitors: 1) COX-1 selective inhibitors (low-dosage aspirin); 2) COX non-selective inhibitors (the majority of classified NSAIDs, which when administered over the long term, e.g., in cases of rheumatoid arthritis, cause duodenal ulcers in 20% of cases and gastric hemorrhage in 1-4% of cases/year); 3) COX-2 preferential inhibitors (meloxicam and nimesulide, which have fewer gastric side effects than standard NSAIDs, but which are not risk-free at high doses); 4) COX-2 selective inhibitors (celecoxib and rofecoxib). Preliminary clinical studies have shown that COX-2 selective inhibitors are as efficient as standard NSAIDs and have fewer adverse digestive side effects, thereby confirming the interest of this proposed classification. In the UK, the aforementioned studies have led to the commercialization of rofecoxib for the treatment of pain and osteoarthritis, while celecoxib has been introduced in medical practice in the USA and other countries for the treatment of rheumatoid arthritis and osteoarthritis. FUTURE PROSPECTS AND PROJECTS: Various epidemiological and laboratory studies have indicated that NSAIDs may be able to reduce the risk of cancer (colorectal cancer in particular) and Alzheimer's disease due to their inhibitory activity on COXs, especially COX-2. The therapeutic contribution of COX-2 specific inhibitors has to be more fully evaluated, particularly as these agents could delay the healing of duodenal ulcers and interfere with several COX-2-induced physiological functions. It is therefore suggested that until further information becomes available, this new class of NSAIDs should be used with caution in certain patient populations.

[Inducible cyclooxygenase. New relationships between non-steroidal anti-inflammatory agents and inhibition of synthesis of prostaglandins]. / Cyclooxygénase inductible. Du nouveau sur les relations entre anti-inflammatoires non stéroïdiens et inhibition de la synthèse des prostaglandines.

After a brief history of the main discoveries concerning the research on arachidonic acid and its biologically active derivatives, recent findings related to the identification of 2 isoenzymes of the prostaglandin-H synthase (PGHS) are reviewed. These isoenzymes play different roles within the body, since PGHS-1 is involved in homeostasis when PGHS-2 is mainly expressed during the inflammatory reaction. Non-steroidal anti-inflammatory drugs classically inhibit the biosynthesis of prostaglandins but this inhibitory effect depends on the considered isoenzyme. This discovery may have pharmacological and clinical impact but, at the present time, research is focused more on new pharmacological targets than on improving drug prescription.

[Non-steroidal anti-inflammatory drugs with selectivity for cyclooxygenase-2 in Alzheimer's disease. Rationale and perspectives]. / Anti-inflammatoires non stéroïdiens sélectifs de la cyclooxygénase-2 pour la maladie d'Alzheimer. Justification et perspectives.

POSSIBLE INFLAMMATORY MECHANISMS: Alzheimer's disease (AD) is a degenerative disease of the brain including possibly inflammatory mechanisms, as illustrated by the presence of activated microglial cells in the periphery of senile plaques and neurofibrillary tangles and the subsequent release of proinflammatory mediators with neurotoxic potency. RATIONALE FOR NSAID USE: Although not firmly demonstrated, the rationale for the prescription of non steroidal anti-inflammatory drugs (NSAIDS) as neuroprotective agents in AD lies on epidemiological data having shown a reduced risk of developing AD in patients on long-term therapy with NSAIDs (non selective cyclo-oxygenase [COX] inhibitors). RATIONALE FOR THE USE OF SELECTIVE COX-2 INHIBITORS: The rationale for the prescription of selective COX-2 inhibitors as neuroprotective drugs in AD lies on: Epidemiological data having shown a reduced risk of developing AD in patients treated with anti-inflammatory doses of classical NSAIDs (inhibition of COX-1 and COX-2) but not with antithrombotic doses of aspirin (selective inhibition of COX-1), Cellular experiments, Demonstration of a better gastro-intestinal (GI) safety profile with selective COX-2 inhibitors than with classical NSAIDs in short-term studies, allowing a possible long-term use in AD. BEFORE PRESCRIBING: COX-2 may have an ambivalent functionality in the brain since the basal production of prostaglandins through COX-2 may participate in neuronal homeostasis whereas the expression of COX-2 is associated with brain development. Classical NSAIDs are ineffective in reducing the formation of senile plaque and neurofibrillary tangles in AD, which is consistent with an ability to reduce inflammation associated with activation of microglia but illustrates their failure to suppress the degenerative process. Prophylactic use of selective COX-2 NSAIDs can be considered on the basis of their good GI safety after 6 months of marketing in United States but need to be confirmed for a longer time. CURRENT TRIALS: Clinical studies focusing on both the prevention and the slowing down of early AD are under way with two recently launched selective COX-2 inhibitors, celecoxib and rofecoxib.

[Familial articular chondrocalcinosis: study of an Alsatian family]. / Les chondrocalcinoses articulaires familiales: étude d'une famille alsacienne.

Familial articular chondrocalcinosis is a chronic articular disease characterized by acute intermittent attacks of arthritis, presence of calcium pyrophosphate dihydrate crystal in synovial fluid, cartilage and periarticular soft tissue and by x rays calcium deposition in articular cartilage. A family originating from Alsace, with an autosomal dominant transmission has been studied. As in English and Argentinean families, a linkage to the short arm of chromosome 5p has been found. These results suggest that a defective gene at this location may be related to the chondrocalcinosis in these families.