Efeitos da inibição da enzima conversora de angiotensina na osteoartrite experimental em ratos

Abstract

The aim of this study was to evaluate the effects of inhibition of angiotensin converting enzyme (ACE) on the pathophysiological response of articular tissues during osteoarthritis (OA). OA was induced with sodium monoiodoacetate (MIA) in Wistar rats and, 7 days later, treatment with captopril (80 mg/kg, daily, gavage) was conducted for 21 days. On day 28, rats were euthanized to obtain joint lavage (total leukocyte count and ELISA) and knee samples for histopathological and immunohistochemical evaluation. Inhibition of ACE did not increase MIA-induced hyperalgesia. Treatment with captopril led to reduced OARSI score, prevented chondrocyte death and loss of proteoglycans, reduced repair tissue, and influenced IL-10 expression in joint cartilage and repair tissue. In addition, reduction of MIA-induced bone changes was observed, there was less fibrous tissue in the bone of the treated animals, which was related to reduction of osteoclasts in the areas of bone resorption and increased expression of IL-10. There was a reduction in the number of leukocytes migrated from synovium and TNF levels, as well as an increase in IL-6 and TGF-β with captopril treatment. In contrast, synovial hyperplasia induced by MIA did not reduce. Similarly to MIA, Ang II injection in the rat knee promoted hyperalgesia, joint edema and increased the number of leukocytes in the joint cavity. Daily injection of Ang II in rat knee for 14 days also triggered mild cationic depletion, chondrocyte disorganization in ECM and chondrocyte death. In order to investigate whether the chondroprotective effects of captopril on OA is related to the inhibition of ACE and consequent reduction of Ang II in the chondrocytes, a primary culture of chondrocytes obtained from the joints of neonatal Wistar rats was performed. Cells were stimulated with MIA or AngII and treated with captopril or enalapril to assess cell viability (MTT), proteoglycan content (Alcian Blue) and mRNA expression by quantitative PCR (AT1R, AT2R, MasR, ACE, ACE2, TGF-β, MMP-13, Col2A1, Aggrecan and Beta-actin). In vitro, chondrocyte stimulation with MIA (6 x 10-6 M) or Ang II (10-5 M) for 36 hours reduced cell viability, which was prevented by treatment with captopril (10-9 M), as well as enalapril (10-9 M). After 14 days, the observed effect was similar for MIA but not for Ang II, as no significant differences were observed between groups. MIA and Ang II stimuli also triggered a reduction in proteoglycan content (percentage of labeled area, 14 days after stimulation) that was restored after captopril treatment. Such a phenotype of RAS modulation by captopril seems to proceed from the ACE / AngII / AT2R axis, since MIA reduced the expression of AT2R mRNA, an effect that was reversed by captopril. Captopril treatment in MIA-stimulated cells also induced reduction of MasR expression and increased mRNA expression of ACE, TGF-β and collagen type II. This work underlines the importance of the local RAS knee, inhibition of ACE with captopril in MIA led to attenuation of cartilage lesions, subchondral bone and normalized recruitment of leukocytes from synovium. We have also seen that Ang II joint injection replicates some of the effects induced by MIA and that captopril protects chondrocytes in vitro after MIA or Ang II stimulation. In conclusion, these data indicate that Ang II is involved in the pathophysiology of OA and uses captopril as a promising therapeutic strategy for knee OA.