Neuroimmune cross-talk in Helicobacter pylori infection: analysis of substance P and vasoactive intestinal peptide expression in gastric enteric nervous system.

It is suggested that different neuropeptides are actively involved in the pathogenesis of Helicobacter pylori (H. pylori)-induced gastritis acting as important effectors of the neuroimmune complex interactions, but the available data is limited and contradictory. The aim of this study was to determine whether the chronic infection generates changes in substance P (SP) and vasoactive intestinal peptide (VIP) gastric level and to evaluate the dependence of these potential effects on the degree of bacterial colonization or the severity of the inflammatory infiltrate. Therefore, immunohistochemical tests were performed to examine SP and VIP expression in mucosal nerve endings and myenteric neurons. Both SP and VIP levels were significantly higher in gastric samples of patients infected with H. pylori compared to uninfected individuals, confirming that these neuropeptides are neuroimmune modulators involved in the pathogenesis of H. pylori infection. Although their expression did not correlate with the intensity of mucosal inflammation nor with the bacterial density, we observed a strong association between SP neuronal level and the degree of myenteric ganglionitis, which in turn correlated with the severity of mucosal T-cell infiltration. These findings suggest that the mechanisms of neuroimmune cross-talk depend on some other factors that remain to be determined.