Patterns of matrix metalloproteinases and transforming growth factor-beta 1 expression during peritoneal repair in chlorhexidine induced peritoneal fibrosis mice

SummaryBackground/PurposeRecovery from peritoneal fibrosis (PF) involves the digestion of accumulated collagens and remodeling. Matrix metalloproteinases (MMPs) may play an important role in repair. The role of MMP-13, an important component in the MMP cascade, in PF is still unclear. We examined the sequential expression of MMP synthesis during repair in a PF mouse.MethodsForty-eight mice at 8 weeks of age were given an intraperitoneal injection of 0.1% chlorhexidine gluconate (CG) for 3 weeks. Control mice were injected with the same dosages of 15% ethanol dissolved in saline. These mice were sacrificed, and anterior abdominal walls were obtained on days 21, 28, 35, 42, 49, and 56. Gene expressions of MMP-2 and -13, tissue inhibition of metalloproteinase-1 (TIMP-1) and -2, MT1-MMP, transforming growth factor-beta 1, and collagen types I and III were analyzed by real-time polymerase chain reaction. MMP-13 enzyme activity was also measured. In immunohistological evaluation, MMP-13 expressing cells were examined.ResultsThickening of the peritoneum and marked infiltration of monocytes were induced by CG, and the alterations remained until 7 days after cessation of CG. Then tissue repair rapidly advanced. Synthesis of collagen types I and III, MMP-2, TIMP-1 and -2, and transforming growth factor-beta 1 in the injured peritoneum was significantly increased until day 28. These increments were preceded by an increase of MMP-13 synthesis and activity after cessation of CG. Some infiltrating macrophages in the thickened peritoneum showed MMP-13 expression early after cessation of CG.ConclusionMMP-13 was synthesized by infiltrating monocytes early in the repair process in the CG-induced PF mouse. After cessation of stimulant, increase of MMP-13 synthesis may act as an inducer of an efficient degradation cascade in collagen-rich peritoneal tissue.背景腹膜纖維化的復原涉及膠原蛋白堆積的消化與其後的重塑，其中，基質金屬蛋白酶(MMPs)在組織修復期間可能佔有重要的角色。作為MMP級聯中的重要一環，MMP-13在腹膜纖維化上的角色仍然未明。本研究透過腹膜纖維化(PF)的小鼠，調查了在腹膜修復期間MMP生成的表現順序。方法研究材料為48隻年齡8週的小鼠，先接受每天共3週的0.1%葡萄糖酸氯己定(CG)腹膜內注射；另外對照組的注射則採用相同容量or劑量含15%乙醇的鹽水。其後陸續宰殺小鼠以取得第21、28、35、42、49及56天的前腹壁檢體，並採用實時PCR測量以下的基因表現：MMP-2-13、TIMP-1-2、MT1-MMP、TGF-β(1)、及I III型膠原蛋白。此外亦同時測量MMP-13之酵素活動，並對表現MMP-13的細胞作免疫組織學評估。結果在CG誘導下，可見腹膜增厚及單核球的明顯浸潤，直至停止CG後7天，其後可見組織修復的快速進行。在停止CG後的受損腹膜中，首先可見MMP-13生成與活動的增加，其後亦可見I III型膠原蛋白、MMP-2、TIMP-1-2、及TGF-β(1)生成的明顯增加，直至第28天。在停止CG後的早期，可見增厚腹膜中有若干巨噬細胞具MMP-13表現。結論在CG所致的PF小鼠中，腹膜修復早期已可見浸潤的單核球產生MMP-13。在停止刺激後，在富含膠原蛋白的腹膜環境中，MMP-13似乎可促使一個高效降解級聯的進行。