Evaluation of expression of neuroglobin, cytoglobin and neurolysin in the intestinal segment in hirschsprung disease

Aim: Hirschsprung's disease (HD) is a developmental disorder characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the distal bowel. According to the widely accepted theory, the fundamental pathology of the disease aganglionosis- is associated with a disruption in neural crest cell migration, which is expected to occur between the 4th and 12th weeks of gestation. An alternative etiological theory suggests that although the cranio-caudal migration of ganglion cells occurs normally, these cells fail to develop or survive due to an inadequate microenvironment. The aim of this study is to contribute novel findings to the existing literature by evaluating the expression of neuroglobin (Ngb), cytoglobin (Cygb) and neurolysin (Nln) in intestinal segments of patients with HD, which has not been previously explored. Material and Method: Pathological specimens from 12 patients who underwent surgery at our center and were histopathologically diagnosed with HD, as well as 12 patients operated for non-HD related conditions (control group), were retrospectively analyzed. The tissues were stained using immunohistochemical methods to assess and compare the expression levels of Ngb, Cygb, and Nln in the intestinal wall. Results: A statistically significant difference was identified in the staining intensity of Ngb within the plexus when comparing the aganglionic zone and the control group. In the subgroup analysis of HD, a statistically significant difference in Ngb staining intensity was also observed between the ganglionic and aganglionic zones. Furthermore, when comparing the Cygb staining intensity at the ganglion level between the ganglionic and aganglionic zones of HD, as well as between the HD aganglionic zone and the control group, statistically significant differences were found. In contrast, immunohistochemical staining with Nln revealed no detectable staining in the tissues, and thus no meaningful results could be obtained. Conclusion: In this study evaluating the etiology of HD, the reduced expression of endopeptidases is interpreted as a consequence of either disruptions in the pathways required for expression or decreased levels due to increased consumption. The study was conducted using histochemical staining, which also serves as a diagnostic method in HD. We identified statistically significant differences in expression levels among the study groups. Accordingly, evaluating endopeptidase expression levels using this method may represent a valuable diagnostic tool for HD. Keywords: Hirschsprung's disease, immunohistochemical, neuroglobin, cytoglobin, neurolysin