Role of substance P and CGRP in gastric MALT lymphoma induced by Helicobacter heilmannii infection (1052.5)

Abstract

Recently, many neuroendocrine mediators have been reported to be related to the formation and enlargement of the neoplasm. From our electron microscopic analysis of the gastric MALT lymphoma, many unmyelinated nerve fiber‐like structures have been detected especially in the early stage of the tumor formation. Thus, the present study was undertaken to clarify the localization of choline acetyltransferase (ChAc), substance P, its receptor NK‐1R, CGRP and RAMP‐1, in the MALT lymphoma tissues. The effect of eradication of the bacilli as well as spantide II, a substance P antagonist, was also investigated. Materials and Methods The gastric, hepatic and pulmonary MALT lymphoma was formed by the per oral administration of homogenized gastric mucosa from Helicobacter heilmannii‐infected mice. The localization of ChAc, substance P, NK‐1R, CGRP and RAMP‐1 was observed by the indirect immunohistochemisty. The eradication treatment was performed by the combined administration of amoxicillin, chlarithromycin and lansoprazole for seven days. Results Substance P immunoreactivity (Ir) was observed in perivascular area within the tumor tissues, and the NK‐1R Ir was distributed mostly on the lymphoma cells. On the other hand, CGRP Ir was recognized in the area surrounding the MALT lymphoma. After the eradication treatment, the substance P Ir as well as CGRP Ir decreased in the reduced lymphoma tissues. Spantide II also induced the size of the tumor. In conclusion, the importance of substance P was shown in the maintenance and enlargement of the MALT lymphoma, having the clinical relevance.