Distribution Of Interstitial Cells Of Cajal And The Gap Junction Protein Connexin43 In Hirschsprung's Disease

The pathophysiology of Hirschsprung' s disease ( HD) is not understood fully. Interstitial cells of Cajal (ICCs) are pacemaker cells of the gastrointestinal tract, which are localized between the nerve and the smooth muscle cells. ICCs is connected by Gap junctions to each other and to the smooth muscle cells. C - kit immunohistochemistry is valuable for the study of the distribution of ICCs with light microscopy in the gut. Connexin43 is regarded as the major Gap junction protein in human.ObjectiveThe current study examines the distribution of ICCs and express of the Gap junction protein Connexin43 by double immunostaining using anti c - kit and an-tiConnexin43 polyclonal antibodies, and investigates the role of ICCs and the Gap junction protein Connexin43 in the pathogenesis of Hirschsprung' s diseaseMethodsTissues were obtained from 11 patients with histologically proven HD ( aging from 5 months to 2. 5 years; male Sand female 3) at the time corrective sur-gery( Soave pull - through). Of whom, 9 cases were classified into common type and 2 into long segment. The distribution of the ICCs and connexin43 in agangli-onic, transitional and dilated segments of HD was studied using SABC double immunohistochemistry approach.ResultsC - kit + ICCs were observed at the inner part of the circular muscle and a-round the myenteric plexus between the two muscle layers . ICCs were fusiform with two long main processes along the longitudinal axis, the nucleus usually were clear. The expression of c - kit + was present in the cytoplasm and the processes of ICCs and its color is blue. In the circular muscular layer, ICCs run parallel to the muscle fibers. In the ganglionic portion of HD, ICCs were abundant within the circular muscle layer and formed a dense cellular network structure. They were also located around the myenteric plexus level, the myenteric plexus were clearly demarcated by ICCs. In the aganglionic segment of HD bowel , ICCs were sparse and only a few ICCs localized around the myenteric plexus region. The number of c - kit+ ICCs was remarkably reduced or even disap-peared in aganglionic segment of bowel in HD. Statistics showed the significant difference of ICCs between the aganglionic and ganglionic bowel segments ( p < 0.001). Immunoreactivity to antiConnexin43 was distributed within the circular and longitudinal smooth muscle layers and in the myenteric plexus region. On double staining the Connexin43 expression was present in the cell body and processes of the c - kit - positive ICCs. The color of expression of Connexin43 is red . The cellular network of ICCs is connected by gap junctions to each other and to the smooth muscle cells. In the ganglionic portion of HD, immunoreactiv-ity to antiConnexin43 was densely and homogeneously distributed as c - kit im-munopositivity. Strong Connexin43 immunoreactivity also was seen at the myenteric plexus region. In the aganglionic part of HD , the Connexin43 staining was obviously weak in the cell bodies of few ICCs, in the smooth muscle layers and in the myenteric plexus region.ConclusionResults of our study show the abnormal distribution of ICCs and the Cap junction protein Connexin43. The lack of ICCs and Connexin43 may lead to theabnormal spontaneous electrical activity and conduction in aganglionic segments and aggravate the incidence of HD.