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

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.

Antibiotic‐induced dysbiosis of the microbiota impairs gut neuromuscular function in juvenile mice

“…Contractility studies were performed as previously described (Giron et al, ; Brun et al, ; Zoppellaro et al, ). Segments (1 cm in length) of mouse distal ileum, proximal to the ileocaecal junction, were isolated and mounted along the longitudinal axis in organ baths containing 10 mL of oxygenated (95% O 2 and 5% CO 2 ) and heated (37°C) Krebs solution (in mM: NaCl 118, NaHCO 3 25, C 6 H 12 O 6 11, KCl 4.7, CaCl 2 ∙2H 2 O 2.5, MgSO 4 ∙1.2, K 2 HPO 4 1.2).…”

“…After 45 min equilibration, ileal segments were stretched passively to an initial tension of 0.5 g and brought to their optimal point of length‐tension relationship using 1 μM carbachol (Brun et al, ; Zoppellaro et al, ). Ileal segments were treated with carbachol to study cholinergic effects or with 60 mM KCl solution to elicit depolarization‐induced contraction.…”

“…Immunofluorescence was performed on distal ileum frozen tissues (0.5 cm segments) embedded in optimal cutting temperature (OCT) Mounting Medium and sectioned (7 μm‐thick) with a cryostat‐microtome (Leica CM 1850 UV, Milan, Italy). The sections were mounted onto Superfrost Plus slides and analysed by immunohistochemistry as previously described (Zoppellaro et al, ; Antonioli et al, ; Antonioli et al, ). Briefly, ileal sections from CNTR and ABX mice were fixed for 15 min with 4% paraformaldehyde in PBS, washed in Tris‐buffer saline (TBS) and incubated with 0.05 M NH 4 Cl.…”

Purinergic signalling in the gastrointestinal tract and related organs in health and disease

“…Allergic diarrhoea, in a model of food allergy, was accompanied by chronic inflammation and mast cell hyperplasia in the colon [434], and it was suggested that sustained alteration in purinergic neurotransmission contributed to the disturbed motility characterised by this condition. Herpes simplex virus type-1 infects the enteric nervous system and affects gut motor function; contractions mediated by adenosine acting via A 1 or A 2A receptors on smooth muscle and A 2A and A 3 receptors in the myenteric plexus were impaired in virus-infected rats [764].…”

NTPDase and 5′-nucleotidase activities in synaptosomes of rabbits experimentally infected with BoHV-5

“…Furthermore, viral infections alter or can be modulated by different components of the purinergic system, for example, NTPDase-6 (CD39L2) is required for foot-and-mouth disease virus replication (Piccone et al 2009), and uridine triphosphate (UTP) through interaction with purinergic receptors P2Y4 increases the production of antibodies against the rabies virus (Iwaki et al 2014). Furthermore, infection by herpes simplex virus may influence the adenosine metabolism by increasing adenosine deaminase and 5′-nucleotidase levels (Zoppellaro et al 2013), and adenosine deaminase inhibitors have been implicated in the in vitro reduction of HSV-1 replication (Williams and Lerner 1975). In addition, several studies have shown altered ectonucleotidase activity and expression associated with various pathologies (Trams and Lauter 1978;Glass et al 1996;Nagy et al 1997;Braun et al 1998;Lunkes et al 2004;Nedeljkovic et al 2006;Lavrnja et al 2009;Gandelman et al 2010).…”