Increased expression of MMP-9 and IL-8 are correlated with poor prognosis of Bladder Cancer

Background: Extracellular matrix homeostasis is strictly maintained by a coordinated balance between the expression of metalloproteinases (MMPs) and their inhibitors. The purpose of this study was to investigate whether the expression of MMP-9, MMP-2 and its specific inhibitors, are expressed in a reproducible, specific pattern and if the profiles are related to prognosis in Bladder Cancer (BC). Methods: MMP-9, MMP-2 and its specific inhibitors expression levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) in fresh-frozen malignant tissue collected from 40 patients with BC submitted to transurethral resection of bladder. The control group consisted of normal bladder tissue from five patients who had undergone retropubic prostatectomy to treat benign prostatic hyperplasia. Results: MMP-9 was overexpressed in 59.0 % of patients, and MMP-2, TIMP-1, TIMP-2, MMP-14, RECK and IL-8 was underexpressed in most of the patients. Regarding prognostic parameters we observed that high-grade tumors exhibited significantly higher levels of MMP-9 and IL-8 (p = 0.012, p = 0.003). Invasive tumors (pT1-pT2) had higher expression levels of MMP-9 than superficial tumors (pTa) (p = 0.026). The same was noted for IL-8 that was more expressed by invasive tumors (p = 0.015, p = 0.048). Most importantly tumor recurrence was related with higher levels of both MMP-9 (p = 0.003) and IL-8 (p = 0.005). Conclusion: We have demonstrated that the overexpression of MMP-9 and higher expression of IL-8 are related to unfavorable prognostic factors of urothelial bladder cancer and tumor recurrence and may be useful in the follow up of the patients.

Rho-kinase inhibition attenuates airway responsiveness, inflammation, matrix remodeling, and oxidative stress activation induced by chronic inflammation

Possa SS, Charafeddine HT, Righetti RF, da Silva PA, Almeida-Reis R, Saraiva-Romanholo BM, Perini A, Prado CM, Leick-Maldonado EA, Martins MA, Tiberio ID. Rho-kinase inhibition attenuates airway responsiveness, inflammation, matrix remodeling, and oxidative stress activation induced by chronic inflammation. Am J Physiol Lung Cell Mol Physiol 303: L939-L952, 2012. First published September 21, 2012; doi:10.1152/ajplung.00034.2012.-Several studies have demonstrated the importance of Rho-kinase in the modulation of smooth muscle contraction, airway hyperresponsiveness, and inflammation. However, the effects of repeated treatment with a specific inhibitor of this pathway have not been previously investigated. We evaluated the effects of repeated treatment with Y-27632, a highly selective Rho-kinase inhibitor, on airway hyperresponsiveness, oxidative stress activation, extracellular matrix remodeling, eosinophilic inflammation, and cytokine expression in an animal model of chronic airway inflammation. Guinea pigs were subjected to seven ovalbumin or saline exposures. The treatment with Y-27632 (1 mM) started at the fifth inhalation. Seventy-two hours after the seventh inhalation, the animals' pulmonary mechanics were evaluated, and exhaled nitric oxide (E-NO) was collected. The lungs were removed, and histological analysis was performed using morphometry. Treatment with Y-27632 in sensitized animals reduced E-NO concentrations, maximal responses of resistance, elastance of the respiratory system, eosinophil counts, collagen and elastic fiber contents, the numbers of cells positive for IL-2, IL-4, IL-5, IL-13, inducible nitric oxide synthase, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, transforming growth factor-beta, NF-kappa B, IFN-gamma, and 8-iso-prostaglandin F2 alpha contents compared with the untreated group (P < 0.05). We observed positive correlations among the functional responses and inflammation, remodeling, and oxidative stress pathway activation markers evaluated. In conclusion, Rho-kinase pathway activation contributes to the potentiation of the hyperresponsiveness, inflammation, the extracellular matrix remodeling process, and oxidative stress activation. These results suggest that Rho-kinase inhibitors represent potential pharmacological tools for the control of asthma.

Ethanol Consumption Alters the Expression and Reactivity of Adrenomedullin in the Rat Mesenteric Arterial Bed

Aims: Adrenomedullin (AM) is a peptide that displays cardiovascular protective activity. We investigated the effects of chronic ethanol consumption on arterial blood pressure, vascular reactivity to AM and the expression of AM system components in the rat mesenteric arterial bed (MAB). Methods: Male Wistar rats were treated with ethanol (20% vol/vol) for 6 weeks. Systolic, diastolic and mean arterial blood pressure were monitored in conscious rats. Vascular reactivity experiments were performed on isolated rat MAB. Matrix metalloproteinase-2 (MMP-2) levels were determined by gelatin zymography. Nitrite and nitrate generation were measured by chemiluminescence. Protein and mRNA levels of pre-pro-AM, CRLR (calcitonin receptor-like receptor) and RAMP1, 2 and 3 (receptor activity-modifying proteins) were assessed by western blot and quantitative real-time polymerase chain reaction, respectively. Results: Ethanol consumption induced hypertension and decreased the relaxation induced by AM and acetylcholine in endothelium-intact rat MAB. Phenylephrine-induced contraction was increased in endothelium-intact MAB from ethanol-treated rats. Ethanol consumption did not alter basal levels of nitrate and nitrite, nor did it affect the expression of MMP-2 or the net MMP activity in the rat MAB. Ethanol consumption increased mRNA levels of pre-pro-AM and protein levels of AM in the rat MAB. Finally, no differences in protein levels or mRNA of CRLR and RAMP1, 2 and 3 were observed after treatment with ethanol. Conclusion: Our study demonstrates that ethanol consumption increases blood pressure and the expression of AM in the vasculature and reduces the relaxation induced by this peptide in the rat MAB.

Ethanol consumption increases the expression of endothelial nitric oxide synthase, inducible nitric oxide synthase and metalloproteinases in the rat kidney

Objectives The effects of longterm ethanol consumption on the levels of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS) and metalloproteinase-2 (MMP-2) were studied in rat kidney. Methods Male Wistar rats were treated with 20% ethanol (v/v) for 6 weeks. Nitrite and nitrate generation was measured by chemiluminescence. Protein and mRNA levels of eNOS and iNOS were assessed by immunohistochemistry and quantitative real-time polymerase chain reaction, respectively. MMP-2 activity was determined by gelatin zymography. Histopathological changes in kidneys and indices of renal function (creatinine and urea) and tissue injury (mitochondrial respiration) were also investigated. Results Chronic ethanol consumption did not alter malondialdehyde levels in the kidney. Ethanol consumption induced a significant increase in renal nitrite and nitrate levels. Treatment with ethanol increased mRNA expression of both eNOS and iNOS. Immunohistochemical assays showed increased immunostaining for eNOS and iNOS after treatment with ethanol. Kidneys from ethanol-treated rats showed increased activity of MMP-2. Histopathological investigation of kidneys from ethanol-treated animals revealed tubular necrosis. Indices of renal function and tissue injury were not altered in ethanol-treated rats. Conclusions Ethanol consumption increased renal metalloproteinase expression/activity, which was accompanied by histopathological changes in the kidney and elevated NO generation. Since iNOS-derived NO and MMPs contribute to progressive renal injury, the increased levels of NO and MMPs observed in ethanol-treated rats might contribute to progressive renal damage.

Identification of protein expression signatures in gastric carcinomas using clustering analysis

Background and Aim: The identification of gastric carcinomas (GC) has traditionally been based on histomorphology. Recently, DNA microarrays have successfully been used to identify tumors through clustering of the expression profiles. Random forest clustering is widely used for tissue microarrays and other immunohistochemical data, because it handles highly-skewed tumor marker expressions well, and weighs the contribution of each marker according to its relatedness with other tumor markers. In the present study, we e identified biologically- and clinically-meaningful groups of GC by hierarchical clustering analysis of immunohistochemical protein expression. Methods: We selected 28 proteins (p16, p27, p21, cyclin D1, cyclin A, cyclin B1, pRb, p53, c-met, c-erbB-2, vascular endothelial growth factor, transforming growth factor [TGF]-beta I, TGF-beta II, MutS homolog-2, bcl-2, bax, bak, bcl-x, adenomatous polyposis coli, clathrin, E-cadherin, beta-catenin, mucin (MUC) 1, MUC2, MUC5AC, MUC6, matrix metalloproteinase [ MMP]-2, and MMP-9) to be investigated by immunohistochemistry in 482 GC. The analyses of the data were done using a random forest-clustering method. Results: Proteins related to cell cycle, growth factor, cell motility, cell adhesion, apoptosis, and matrix remodeling were highly expressed in GC. We identified protein expressions associated with poor survival in diffuse-type GC. Conclusions: Based on the expression analysis of 28 proteins, we identified two groups of GC that could not be explained by any clinicopathological variables, and a subgroup of long-surviving diffuse-type GC patients with a distinct molecular profile. These results provide not only a new molecular basis for understanding the biological properties of GC, but also better prediction of survival than the classic pathological grouping.

Adjunct effect of the antimicrobial photodynamic therapy to an association of non-surgical and surgical periodontal treatment in modulation of gene expression

Background: This study has evaluated the effect of antimicrobial photodynamic therapy (aPDT) used in conjunction with non-surgical and surgical periodontal treatment (PT) in modulating gene expression during periodontal wound healing. Methods: Fifteen patients with chronic periodontitis, presenting bilaterally lower molars with class III furcation lesions and scheduled for extraction, were selected. In initial therapy, scaling and root planing (SRP) was performed in the Control Group (CG), while SRP + aPDT were performed in the Test Group (TG). 45 days later, flap surgery plus SRP, and flap surgery plus SRP + aPDT were performed in the CG and TG, respectively. At 21 days post-surgery, the newly formed granulation tissue was collected, and Real-time PCR evaluated the expression of the genes: tumor necrosis factor-?, interleukin-1?, interleukin-4, interleukin-10, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2), osteoprotegerin (OPG), receptor activator of nuclear factor- ?B ligand (RANKL), type I collagen, alkaline phosphatase, osteopontin, osteocalcin, and bone sialoprotein. Results: There were statistically significant differences between the groups in relation to mRNA levels for MMP-2 (TG = 3.26 ± 0.89; CG = 4.23 ± 0.97; p = 0.01), TIMP-2/MMP-2 ratio (TG = 0.91 ± 0.34; CG = 0.73 ± 0.32; p = 0.04), OPG (TG = 0.84 ± 0.45; CG = 0.30 ± 0.26; p = 0.001), and OPG/RANKL ratio (TG = 0.60 ± 0.86; CG = 0.23 ± 0.16; p = 0.04), favoring the TG. Conclusion: The present data suggest that the aPDT associated to nonsurgical and surgical periodontal therapy may modulate the extracellular matrix and bone remodeling by up regulating the TIMP- 2/MMP-2 and OPG/RANKL mRNA ratio, but the clinical relevance needs to be evaluated in further studies.

Matrix metalloproteinases and angiogenic factors: predictors of survival after radical prostatectomy for clinically organ-confined prostate cancer?

The aim of the present study was to investigate whether biomarkers improve the prediction of recurrence-free, disease-specific, and overall survival in patients with clinically localized prostate cancer. A tissue microarray was constructed from prostate specimens of 278 patients who underwent open radical retropubic prostatectomy for clinically localized prostate cancer. For immunohistochemical studies, antibodies were used against matrix metalloproteinase (MMP)-2, MMP-3, MMP-7, MMP-9, MMP-13, and MMP-19, as well as against vascular endothelial growth factor, hypoxia-induced factor 1 , basic fibroblast growth factor, and cluster of differentiation 31. Univariate and multivariable analyses were performed to evaluate the potential predictors of overall, disease-specific, and recurrence-free survival. In univariate analysis of patients with clinically organ-confined prostate cancer, only higher expression levels of MMP-9 (hazard ratio [0.6], 95% CI 0.45-0.8) had a protective effect in terms of overall survival. This positive effect of high MMP-9 expression was also observed for recurrence-free (HR 0.88, 95% CI 0.78-0.99) and disease-specific survival (HR 0.5, 95% CI 0.36-0.73). In multivariable analysis, none of these potential markers was found to be an independent prognostic factor of survival. Of all MMPs and angiogenic factors tested, MMP-9 expression has the potential as a prognostic marker in patients undergoing radical prostatectomy for clinically organ-confined cases of prostate cancer.

The immunomodulator FTY720 and its phosphorylated derivative activate the Smad signalling cascade and upregulate connective tissue growth factor and collagen type IV expression in renal mesangial cells

1.--The immunomodulating agent FTY720 is a substrate for the sphingosine kinase and the phosphorylated form is able to bind to sphingosine 1-phosphate (S1P) receptors. In this study, we show that exposure of renal mesangial cells to phospho-FTY720 leads to a rapid and transient activation of several protein kinase cascades, including the mitogen- and stress-activated protein kinases. The nonphosphorylated FTY720 also increased MAPK phosphorylation, but with a reduced potency and a more delayed time course. In addition, phospho-FTY720 and FTY720 are able to increase phosphorylation of Smad proteins which are classical members of the transforming growth factor-beta (TGF-beta) signalling device, thus suggesting a crosstalk between FTY720 and TGF-beta signalling. 2.--Pretreatment with the S1P(3) receptor antagonist suramin inhibits FTY720 and phospho-FTY720-induced Smad phosphorylation, whereas pertussis toxin pretreatment, which blocks G(i/0) proteins, has no effect on Smad phosphorylation. 3.--Since TGF-beta is a potent profibrotic cytokine in mesangial cells and upregulates the connective tissue growth factor (CTGF) and collagen as important hallmarks in the fibrotic sequelae, we investigated whether FTY720 and phospho-FTY720 are able to mimic these effects of TGF-beta. Indeed, FTY720 and phospho-FTY720 markedly upregulate CTGF and collagen type IV protein expressions. In addition, the tissue inhibitor of metalloproteinase-1 is transcriptionally activated by FTY720, whereas cytokine-induced matrix metalloproteinase-9 is down-regulated by FTY720. 4.--Depletion of the TGF-beta receptor type II by the siRNA transfection technique blocks not only Smad phosphorylation but also CTGF upregulation. Similarly, Smad-4 depletion by siRNA transfection also abrogates CTGF upregulation induced by FTY720 and phospho-FTY720. 5.--In summary, our data show that FTY720 and phospho-FTY720 not only activate the Smad signalling cascade in mesangial cells, but also upregulate the expression of CTGF and collagen. These findings suggest that FTY720 may have additional effects besides the established immunomodulatory action and, importantly, a profibrotic activity has to be considered in future experimental approaches.

Differential gene and protein expression in abluminal sprouting and intraluminal splitting forms of angiogenesis

In adult skeletal muscle, abluminal sprouting or longitudinal splitting of capillaries can be initiated separately by muscle overload and elevated microcirculation shear stress respectively. In the present study, gene and protein expression patterns associated with the different forms of angiogenesis were examined using a targeted gene array (Superarray), validated by quantitative RT (reverse transcription)-PCR and immunoblots. Sprouting angiogenesis induced large changes in expression levels in genes associated with extracellular matrix remodelling, such as MMP-2 (matrix metalloproteinase-2), TIMP (tissue inhibitor of metalloproteinases), SPARC (secreted protein, acidic and rich in cysteine) and thrombospondin. Changes in neuropilin, midkine and restin levels, which may underpin changes in endothelial morphology, were seen during splitting angiogenesis. Up-regulation of VEGF (vascular endothelial growth factor), Flk-1, angiopoietin-2 and PECAM-1 (platelet/endothelial cell adhesion molecule-1) was seen in both forms of angiogenesis, representing a common angiogenic response of endothelial cells. In conclusion, the present study demonstrates that general angiogenic signals from growth factors can be influenced by the local microenvironment resulting in differing forms of capillary growth to produce a co-ordinated expansion of the vascular bed.

Temporal expression of inflammatory mediators in brain basilar artery vasculitis and cerebrospinal fluid of rabbits with coccidioidal meningitis

Strokes due to transmural vasculitis associated with coccidioidal meningitis result in significant morbidity and mortality. The immunological and inflammatory processes responsible are poorly understood. To determine the inflammatory mediators, i.e. cytokines, chemokines, iNOS, matrix metalloproteinase-9 (MMP-9), that possibly contribute to vasculitis, temporal mRNA expression in brain basilar artery samples and MMP-9 protein in the CSF of male NZW rabbits infected intracisternally with 6.5 x 10(4) arthroconidia of Coccidioides immitis were assessed. Five infected and 3 sham-injected rabbits at each time point were euthanized 4, 9, 14 and 20 days post infection. All infected rabbits had neurological abnormalities and severe vasculitis in the basilar arteries on days 9-20. In basilar arteries of infected animals versus controls, mRNAs encoding for IL-6, iNOS, IFN-gamma, IL-2, MCP-1, IL-1beta, IL-10, TNF-alpha, CCR-1, MMP-9, TGF-beta, as well as MMP-9 protein in CSF, were found to be significantly up-regulated. Thus, this study identified inflammatory mediators associated with CNS vasculitis and meningitis due to C. immitis infection. Assessment of the individual contribution of each mediator to vasculitis may offer novel approaches to the treatment of coccidioidal CNS infection. This study also provides unique methodology for immunology studies in a rabbit model.

Basement membrane remodeling in skeletal muscles of patients with limb ischemia involves regulation of matrix metalloproteinases and tissue inhibitor of matrix metalloproteinases

BACKGROUND/AIM: Because the pericapillary basement membrane in skeletal muscles of patients with chronic critical limb ischemia (CLI) is thickened, we determined the expression patterns of genes involved in collagen metabolism, using samples from 9 CLI patients, 4 patients with acute limb ischemia and 4 healthy controls. METHODS: Gene array analysis, quantitative RT-PCR and semiquantitative grading of immunohistochemical reactivity were performed to determine mRNA/cDNA and protein concentrations. RESULTS: In CLI patients compared to controls, cDNA levels of matrix metalloproteinase (MMP)-9 and MMP-19 were higher, collagen type IV chains A1 and A2, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 were similar and MMP-2 were lower. On the protein level, MMP-2, MMP-9, MMP-19 and TIMP-1 were more abundantly expressed. In skeletal muscles from patients with acute limb ischemia, cDNA and protein levels of MMP-9, MMP-19, collagen type IV chains, TIMP-1 and TIMP-2 were high. MMP-2 was elevated at the protein but decreased on the cDNA level. CONCLUSION: Expression of basement membrane components in skeletal muscles of CLI and acute limb ischemia patients is altered, possibly contributing to the pathogenesis of peripheral arterial disease.

Extracts of Lindera obtusiloba induce antifibrotic effects in hepatic stellate cells via suppression of a TGF-beta-mediated profibrotic gene expression pattern

Liver fibrosis is characterized by high expression of the key profibrogenic cytokine transforming growth factor (TGF)-beta and the natural tissue inhibitor of metalloproteinases (TIMP)-1, leading to substantial accumulation of extracellular matrix. Liver fibrosis originates from various chronic liver diseases, such as chronic viral hepatitis that, to date, cannot be treated sufficiently. Thus, novel therapeutics, for example, those derived from Oriental medicine, have gained growing attention. In Korea, extracts prepared from Lindera obtusiloba are used for centuries for treatment of inflammation, improvement of blood circulation and prevention of liver damage, but experimental evidence of their efficacy is lacking. We studied direct antifibrotic effects in activated hepatic stellate cells (HSCs), the main target cell in the fibrotic liver. L. obtusiloba extract (135 mug/ml) reduced the de novo DNA synthesis of activated rat and human HSCs by about 90%, which was not accompanied by cytotoxicity of HSC, primary hepatocytes and HepG2 cells, pointing to induction of cellular quiescence. As determined by quantitative polymerase chain reaction, simultaneous treatment of HSCs with TGF-beta and L. obtusiloba extract resulted in reduction of TIMP-1 expression to baseline level, disruption of the autocrine loop of TGF-beta autoinduction and increased expression of fibrolytic matrix metalloproteinase (MMP)-3. In addition, L. obtusiloba reduced gelatinolytic activity of HSC by interfering with profibrogenic MMP-2 activity. Since L. obtusiloba extract prevented intracellular oxidative stress experimentally induced by tert-butylhydroperoxide, we concluded that the direct antifibrotic effect of L. obtusiloba extract might be mediated by antioxidant activity. Thus, L. obtusiloba, traditionally used in Oriental medicine, may complement treatment of chronic liver disease.

α1 and α2 Integrins Mediate Invasive Activity of Mouse Mammary Carcinoma Cells through Regulation of Stromelysin-1 Expression

Tumor cell invasion relies on cell migration and extracellular matrix proteolysis. We investigated the contribution of different integrins to the invasive activity of mouse mammary carcinoma cells. Antibodies against integrin subunits α6 and β1, but not against α1 and α2, inhibited cell locomotion on a reconstituted basement membrane in two-dimensional cell migration assays, whereas antibodies against β1, but not against α6 or α2, interfered with cell adhesion to basement membrane constituents. Blocking antibodies against α1 integrins impaired only cell adhesion to type IV collagen. Antibodies against α1, α2, α6, and β1, but not α5, integrin subunits reduced invasion of a reconstituted basement membrane. Integrins α1 and α2, which contributed only marginally to motility and adhesion, regulated proteinase production. Antibodies against α1 and α2, but not α6 and β1, integrin subunits inhibited both transcription and protein expression of the matrix metalloproteinase stromelysin-1. Inhibition of tumor cell invasion by antibodies against α1 and α2 was reversed by addition of recombinant stromelysin-1. In contrast, stromelysin-1 could not rescue invasion inhibited by anti-α6 antibodies. Our data indicate that α1 and α2 integrins confer invasive behavior by regulating stromelysin-1 expression, whereas α6 integrins regulate cell motility. These results provide new insights into the specific functions of integrins during tumor cell invasion.

Expression of the Recessive Glomerulosclerosis Gene Mpv17 Regulates MMP-2 Expression in Fibroblasts, the Kidney, and the Inner Ear of Mice

The recessive mouse mutant Mpv17 is characterized by the development of early-onset glomerulosclerosis, concomitant hypertension, and structural alterations of the inner ear. The primary cause of the disease is the loss of function of the Mpv17 protein, a peroxisomal gene product involved in reactive oxygen metabolism. In our search of a common mediator exerting effects on several aspects of the phenotype, we discovered that the absence of the Mpv17 gene product causes a strong increase in matrix metalloproteinase 2 (MMP-2) expression. This was seen in the kidney and cochlea of Mpv17-negative mice as well as in tissue culture cells derived from these animals. When these cells were transfected with the human Mpv17 homolog, an inverse causal relationship between Mpv17 and MMP-2 expression was established. These results indicate that the Mpv17 protein plays a crucial role in the regulation of MMP-2 and suggest that enhanced MMP-2 expression might mediate the mechanisms leading to glomerulosclerosis, inner ear disease, and hypertension in this model.

Régulation de l'expression de PPARγ dans l'arthrose

L’arthrose (OA) est une maladie dégénérative très répondue touchant les articulations. Elle est caractérisée par la destruction progressive du cartilage articulaire, l’inflammation de la membrane synoviale et le remodelage de l’os sous chondral. L’étiologie de cette maladie n’est pas encore bien définie. Plusieurs études ont été menées pour élucider les mécanismes moléculaires et cellulaires impliqués dans le développement de l’OA. Les effets protecteurs du récepteur activé par les proliférateurs de peroxysomes gamma (PPARγ) dans l'OA sont bien documentés. Il a été démontré que PPARγ possède des propriétés anti-inflammatoires et anti-cataboliques. Aussi, plusieurs stimuli ont été impliqués dans la régulation de l’expression de PPARγ dans différents types cellulaires. Cependant, les mécanismes exacts responsables de cette régulation ainsi que le profil de l’expression de ce récepteur au cours de la progression de l’OA ne sont pas bien connus. Dans la première partie de nos travaux, nous avons essayé d’élucider les mécanismes impliqués dans l’altération de l’expression de PPARγ dans cette maladie. Nos résultats ont confirmé l’implication de l’interleukine-1β (IL-1β), une cytokine pro-inflammatoire, dans la réduction de l’expression de PPARγ au niveau des chondrocytes du cartilage articulaire. Cet effet coïncide avec l'induction de l’expression du facteur de transcription à réponse précoce de type 1 (Egr-1). En plus, la diminution de l'expression de PPARγ a été associée au recrutement d'Egr-1 et la réduction concomitante de la liaison de Sp1 au niveau du promoteur de PPARγ. Dans la deuxième partie de nos travaux, nous avons évalué le profil d’expression de ce récepteur dans le cartilage au cours de la progression de cette maladie. Le cochon d’inde avec OA spontanée et le chien avec OA induite par rupture du ligament croisé antérieur (ACLT) deux modèles animaux d’OA ont été utilisés pour suivre l’expression des trois isoformes de PPARs : PPAR alpha (α), PPAR béta (β) et PPAR gamma (γ) ainsi que la prostaglandine D synthase hématopoïétique (H-PGDS) et la prostaglandine D synthase de type lipocaline (L-PGDS) deux enzymes impliquées dans la production de l’agoniste naturel de PPARγ, la 15-Deoxy-delta(12,14)-prostaglandine J(2) (15d-PGJ2). Nos résultats ont démontré des changements dans l’expression de PPARγ et la L-PGDS. En revanche, l’expression de PPARα, PPARβ et H-PGDS est restée stable au fil du temps. La diminution de l’expression de PPARγ dans le cartilage articulaire semble contribuer au développement de l’OA dans les deux modèles animaux. En effet, le traitement des chondrocytes par de siRNA dirigé contre PPARγ a favorisé la production des médiateurs arthrosiques tels que l'oxyde nitrique (NO) et la métalloprotéase matricielle de type 13 (MMP-13), confirmant ainsi le rôle anti-arthrosique de ce récepteur. Contrairement à ce dernier, le niveau d'expression de la L-PGDS a augmenté au cours de la progression de cette maladie. La surexpression de la L-PGDS au niveau des chondrocytes humains a été associée à la diminution de la production de ces médiateurs arthrosiques, suggérant son implication dans un processus de tentative de réparation. En conclusion, l’ensemble de nos résultats suggèrent que la modulation du niveau d’expression de PPARγ, de la L-PGDS et d’Egr-1 au niveau du cartilage articulaire pourrait constituer une voie thérapeutique potentielle dans le traitement de l’OA et probablement d’autres formes d'arthrite.