Role of four and one half LIM domain protein FHL2 on intestinal anastomotic healing

Abstract

Four and one half LIM domain protein FHL2 participates in many cellular processes involved in tissue repair such as regulation of gene expression, cytoarchitecture, cell adhesion, migration and signal transduction. The repair process after wounding is initiated by the release of peptides and bioactive lipids. These molecules induce synthesis and deposition of a provisional extracellular matrix. Sphingosine-1-phosphate and lysophoshatidic acid trigger a signal transduction cascade mediating nuclear shuttling of FHL2. FHL2-deficient mice have impaired cutaneous wound healing. These results prompted us to study further the role of FHL2 in the context of anastomotic wound healing. Colonic anastomoses from Fhl2/C57Bl6 mice and FHL2-deficient mice were used as a model to investigate possible healing disorders. Anastomotic segments were removed 2-, 5- and 14 days after surgery and used for functional (anastomotic bursting pressure), histochemical (anastomotic healing score, cross polarisation microscopy) and molecular (collagen I and III) investigations. A total of 68 wild-type and 70 FHL2-deficient mice with intestinal anastomoses were evaluated prospectively. Anastomotic failure rate was higher in the FHL2 deficient group. Histological evaluation revealed severely impaired wound healing of FHL2 deficient mice anastomoses. They showed reduced mucosal and muscular continuity and granulation tissue deposition in the representative anastomosis compared with wild type mice at day 5 and 14 after surgery. At all time points, the mean anastomotic bursting pressure in Fhl2-deficient mice was significantly lower than in wild-type mice. Cross polarization microscopy highlighted significantly thinner collagen I/collagen III networks in the submucosa of FHL2 deficient mice. At the molecular level we found significant down-regulation of collagen III mRNA expression in FHL2-deficient mice during regeneration with a maximum at day 5 after wounding. In summary, our results showed that FHL2 signalling is mechanistically involved in regulating intestinal healing and thus may represent a new therapeutic target.