腹膜硬化モデルマウスにおけるTranilast(リザベン^[○!R])の腹膜硬化抑制効果についての検討  [in Japanese] Effect of Tranilast on chlorhexidine gluconate (CH)-induced sclerosing peritonitis in a mouse model  [in Japanese]

目的:長期の腹膜透析療法では,血管新生を伴う腹膜の線維性硬化が惹き起こされ,中皮細胞の脱落を起こし被嚢性腹膜硬化症を発症することがあるが,詳細な発症および進展機序は明らかではない.最近の研究では,その機序として種々の成長因子の関与が検討されている.今回,クロールヘキシジングルコネート(CH)腹膜硬化モデルマウスを用いてケミカルメディエーター遊離抑制薬であるTranilastの腹膜硬化抑制およびサイトカイン放出抑制効果について経時的に検討した.対象: C57BL/6JマウスにCHを週3回,3週間腹腔内に投与して腹膜硬化モデルをCH群,Tranilastを投与した群をCH+Tranilast群および15%エタノール生食投与した群をコントロール群とした.方法:CH群とCH+Tranilast群の腹膜の厚さの比較や抗ビメンチン抗体,抗cytokeratin Pan抗体および抗肝細胞増殖因子(HGF)抗体を用いて免疫組織化学的検討を行った.さらに,トランスフォーミング増殖因子-β1 (TGF-β1)およびIII型コラーゲンについてRT-PCRで半定量的に検討した.結果:CH群では経時的に腹膜は肥厚していたが,CH+Tranilast群では14日目まではCH群と比較して明らかに腹膜の肥厚が抑制され,表層にHGF陽性細胞を認めた.さらにCH+Tranilast群のTGF-β1およびIII型コラーゲンmRNA発現は,CH群に比べ抑制されていた.しかし,21日目には腹膜の肥厚は増悪傾向となり,III型コラーゲンmRNA発現も上昇していた.結論:TranilastはTGF-β1の抑制および中皮細胞の脱落を抑制することにより,腹膜の線維性肥厚の進展を遅延させる可能性が示唆された.

Objective: Encapsulating peritoneal sclerosis is a common complication in long-term peritoneal dialysis patients. Peritoneal fibrotic thickening is closely related to decreased ultrafiltration. Several growth factors might induce peritoneal fibrosis. Tranilast, an inhibitor of chemical mediator release, attenuates myocardial and skin fibrosis. The present study investigated whether Tranilast affects the development of peritoneal fibrosis and inhibits cytokine release in a CH-induced sclerosing peritonitis mouse model. Material: C57B06CrSlc mice were given intraperitoneal injections of 0.2ml/20g body weight (BW) of 0.1% chlorhexidine gluconate for 21 days every other day (CH group). Some CH mice were alternately administered 6mg/20g BW of Tranilast by intraperitoneal injection (CH+Tranilast group). These mice were sacrificed on days 7, 14 or 21 after the injection. Method: Parietal peritoneum was analyzed by light microscopy. Immunohistochemical staining was performed using anti-vimentin, anti-cytokeratin PAN and anti-hepatocyte growth factor (HGF) antibodies. The mRNA expressions of transforming growth factor-β1 (TGF-β1) and Type-III collagen were determined by semi-quantitative RT-PCR. Result: Thickening of the submesothelial compact zone gradually increased in the CH group. In the CH+Tranilast group, the increase of this zone was markedly suppressed until day 14 and HGF positive cells were observed in the superficial layer until day 14. Furthermore, mRNA expressions of TGF-β1 and Type-III collagen were suppressed in the CH+Tranilast group until day 14. But thickening of the submesothelial compact zone and mRNA expression of Type-III collagen increased at day 21. Conclusion: It appears that Tranilast might delay the development of peritoneal fibrosis by suppression of TGF-β1 and maintenance of peritoneal mesothelial cells in the CH-induced sclerosing peritonitis mouse model.