Adenosinergic System Involvement in Ischemic Stroke Patients' Lymphocytes.

Silvia Pasquini,Ilaria Casetta,Stefania Merighi,Stefania Gessi,Pier Andrea Borea,Michele Laudisi,Katia Varani,Fabrizio Vincenzi

doi:10.3390/cells9051072

Abstract

Adenosine modulates many physiological processes through the interaction with adenosine receptors (ARs) named as A1, A2A, A2B, and A3ARs. During ischemic stroke, adenosine mediates neuroprotective and anti-inflammatory effects through ARs activation. One of the dominant pathways generating extracellular adenosine involves the dephosphorylation of ATP by ecto-nucleotidases CD39 and CD73, which efficiently hydrolyze extracellular ATP to adenosine. The aim of the study is to assess the presence of ARs in lymphocytes from ischemic stroke patients compared to healthy subjects and to analyze changes in CD39 and CD73 expression in CD4+ and CD8+ lymphocytes. Saturation binding experiments revealed that A2AARs affinity and density were significantly increased in ischemic stroke patients whilst no differences were found in A1, A2B, and A3ARs. These results were also confirmed in reverse transcription (RT)-polymerase chain reaction (PCR) assays where A2AAR mRNA levels of ischemic stroke patients were higher than in control subjects. In flow cytometry experiments, the percentage of CD73+ cells was significantly decreased in lymphocytes and in T-lymphocyte subclasses CD4+ and CD8+ obtained from ischemic stroke patients in comparison with healthy individuals. These data corroborate the importance of the adenosinergic system in ischemic stroke and could open the way to more targeted therapeutic approaches and biomarker development for ischemic stroke.

Highlights

Adenosine is one of the most important nucleosides in the human body, derived from the backbone of adenosine triphosphate (ATP) and strictly implicated in the regulation of a large number of physiological and pathological signals [1,2]
A2A adenosine receptors (ARs) mRNA Expression is Up-Regulated in Lymphocytes of Ischemic Stroke Patients
Saturation binding experiments allowed to determine the density, expressed as Bmax, and the ARsexpressed mRNA expression was in evaluated quantitative assay in lymphocytes affinity, as KD, of ARs ischemicby stroke patients’reverse transcription (RT)-polymerase chain reaction (PCR)

Summary

Introduction

Adenosine is one of the most important nucleosides in the human body, derived from the backbone of adenosine triphosphate (ATP) and strictly implicated in the regulation of a large number of physiological and pathological signals [1,2]. Ischemic stroke is a complex pathology characterized by the sudden loss of blood circulation to an area of the brain and results in a corresponding loss of neurologic function [5]. The extracellular concentration of adenosine increases during ischemia with values in the range of 1000 nM in the first 20 min and return to basal values after about 4 hours [7]. Adenosine seems to have a role as an endogenous mediator of neuroprotection in the homeostatic response to changes occurring during ischemia [9]. ARs could be interesting targets for therapeutic implementation in the treatment of stroke given the rise in adenosine concentration after ischemia [10]. ARs reproduce in the periphery a similar dysfunction present in the brain suggesting that the receptor alteration, measurable, could underlie disease mechanisms [11,12]

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