Adenosine-Mediated Enteric Neuromuscular Function Is Affected during Herpes Simplex Virus Type 1 Infection of Rat Enteric Nervous System

Chiara Zoppellaro,Veronica Macchi,Maria Cecilia Giron,Anna Bin,Ignazio Castagliuolo,Serena Banzato,Paola Brun

doi:10.1371/journal.pone.0072648

Abstract

Adenosine plays an important role in regulating intestinal motility and inflammatory processes. Previous studies in rodent models have demonstrated that adenosine metabolism and signalling are altered during chronic intestinal inflammatory diseases. However, the involvement of the adenosinergic system in the pathophysiology of gut dysmotility associated to a primary neurodysfunction is still unclear. Recently, we showed that the neurotropic Herpes simplex virus type-1 (HSV-1), orally inoculated to rodents, infects the rat enteric nervous system (ENS) and affects gut motor function without signs of systemic infection. In this study we examined whether changes in purinergic metabolism and signaling occur during permanent HSV-1 infection of rat ENS. Using isolated organ bath assays, we found that contraction mediated by adenosine engagement of A1 or A2A receptors was impaired at 1 and 6 weeks post-viral administration. Immunofluorescence studies revealed that viral infection of ENS led to a marked redistribution of adenosine receptors: A1 and A2B receptors were confined to the muscle layers whereas A2A and A3 receptors were expressed mainly in the myenteric plexus. Viral-induced ENS neurodysfunction influenced adenosine metabolism by increasing adenosine deaminase and CD73 levels in longitudinal muscle-myenteric plexus with no sign of frank inflammation. This study provides the first evidence for involvement of the adenosinergic system during HSV-1 infection of the ENS. As such, this may represent a valid therapeutic target for modulating gut contractility associated to a primary neurodysfunction.

Highlights

Gastrointestinal neuromuscular diseases (GINMD), including chronic idiopathic intestinal pseudo-obstruction and irritable bowel syndrome, are a clinically heterogeneous group of diseases presumed to result from morpho-functional alterations of the enteric nervous system (ENS), in the absence of evident structural or biochemical abnormalities
Reagents Purified rabbit anti-human adenosine deaminase (ADA) polyclonal antibody was purchased from SantaCruz Biotechnology Inc., rabbit anti-rat A1 receptor (A1R), rabbit anticanine A2AR, rabbit anti-human A2BR, and rabbit anti-rat A3R polyclonal antibodies were from AlphaDiagnostic International (San Antonio, USA), and mouse anti-rat CD73 was from BD Biosciences (Milan, Italy)
Was still detectable in myenteric ganglia, viral DNA copy number was reduced as compared to the first week after intragastric administration

Summary

Introduction

Gastrointestinal neuromuscular diseases (GINMD), including chronic idiopathic intestinal pseudo-obstruction and irritable bowel syndrome, are a clinically heterogeneous group of diseases presumed to result from morpho-functional alterations of the enteric nervous system (ENS), in the absence of evident structural or biochemical abnormalities. These disorders are characterized by motor impairments and abnormal visceral perception and secretion, with high morbidity and occasional fatal outcome [1,2]. HSV-1 shedding from the oropharyngeal mucosa occurs in chronically infected human subjects facilitating virus passage to the gastrointestinal tract mucosa where it infects the nodose and celiac ganglia

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