Up-regulated FHL1 Expression Maybe Involved in the Prognosis of Hirschsprung's Disease

BACKGROUND In a subset of patients with Hirschsprung's disease (HSCR), gastrointestinal motor dysfunction persisted long after surgical correction. Gastrointestinal motility is achieved through the coordinated activity of the enteric nervous system, interstitial cells of Cajal, and smooth muscle (SMC) cells. Inhibition of four-and-a-half LIM protein-1 (Fhl1) expression by siRNA significantly decreases pulmonary artery SMCs migration and proliferation. Furthermore when up-expressing FHL1 in atrial myocytes, K (+) current density markedly increases, therefore changing myocytes' response to an electrical stimulus. However whether FHL1 in colon SMCs (the final effector organ) influences intestinal motility in HSCR patients has not been clarified. METHODS FHL1 mRNA and protein expressions were analyzed in 32 HSCR colons and 4 normal colons. RESULTS Smooth muscle layers were thicken and disorganized in HSCR. FHL1 was expressed in the ganglion cells of the myenteric plexus, submucosa, as well as in the longitudinal and circular muscle layer of the ganglionic colon. FHL1 mRNA relative expression level in aganglionic colons was 1.06 ± 0.49 (ganglionic colon relative expression level was 1) (P=0.44). FHL1 protein gray level relative to GAPDH in normal colons was 0.83 ± 0.09. FHL1 expression level in ganglionic colon (1.66 ± 0.30) or aganglionic colon (1.81 ± 0.35) was significantly higher than that in normal colons (P=0.045 and P=0.041, respectively). Meanwhile, we found FHL1 expression in aganglionic colon was slightly stronger than that in ganglionic colon (P=0.036). CONCLUSION These data suggested that up-regulated FHL1 in smooth muscle in HSCR might be associated with intestinal wall remodeling in HSCR and might be one of the risk factors for gastrointestinal motor dysfunction.