Adenosine A2A receptor agonist ameliorates EAE and correlates with Th1 cytokine‐induced blood brain barrier dysfunction via suppression of MLCK signaling pathway

Abstract

IntroductionMultiple sclerosis (MS) disease activity is associated with blood‐brain barrier (BBB) disruption, which is mediated by inflammatory cytokines released by CD4+ lymphocytes. To assess the effects of adenosine A2A receptors on BBB permeability in vitro and in vivo.MethodsA2A receptor expression was detected by immunostaining in experimental autoimmune encephalomyelitis (EAE) C57BL/6 mice immunized with myelin oligodendrocyte glycoprotein (MOG)35–55, and human MS brain. F‐actin and the tight junction protein Claudin‐5 were assessed in endothelial cells treated with an A2A receptor specific agonist (CGS‐21680) after Th1 cytokine stimulation. EAE mice were divided into control and CGS‐21680 (50 µg/kg, i.p., daily) groups. Disease scores were recorded daily to evaluate neurological impairment. The effects of A2A receptor on inflammation and demyelination were assessed after euthanasia by immunostaining or histology; BBB permeability was measured by sodium fluoride (Na‐F) and FITC‐dextran amounts.ResultsEndothelial A2A receptor was detected in demyelination areas of MS brain samples. In EAE lesions, A2A receptor was expressed in the endothelium in association with immune cell infiltration. Treatment with CGS‐21680 counteracted the effects of Th1 cytokines on endothelial cells in vitro, preventing the reduction of tight junction protein expression and stress fiber formation. The effects of A2A receptor activation were correlated with MLCK phosphorylation signaling repression. In EAE, A2A receptor agonist decreased BBB permeability and inhibited EAE neurologic deficiency in mice.ConclusionsA2A receptor activation at EAE onset helps reduce the effects of Th1 stimulation on BBB permeability, indicating that A2A receptor mediates BBB function in CNS demyelinated disease.

The peripheral immune response after stroke—A double edge sword for blood‐brain barrier integrity

“…Th1 cells promote BBB permeability by secreting proinflammatory cytokines (IL‐2, IFN‐γ, and TNF‐α) and mediating a cellular immune response . IFN‐γ activates the small GTPase RhoA and increases the expression of Rho‐associated kinase (ROCK), which in turn phosphorylates and activates MLC . TNF‐α stimulates NF‐kβ to increase myosin light chain kinase (MLCK) transcription, which further correlates with increased MLCK protein levels, MLC hyper‐phosphorylation, and paracellular permeability.…”

Anti-IL-6 receptor antibody improves pain symptoms in mice with experimental autoimmune encephalomyelitis

“…Notably, MR16-1 could be detected in the CSF of EAE mice, and the CFS:serum ratio of MR16-1 concentration was greater in EAE mice than in normal mice. Because the blood-brain barrier function is disrupted in EAE mice (Liu et al, 2018), it may be easier for MR16-1 to reach the CNS in EAE mice. Therefore, it is possible that the analgesic effect of MR16-1 was exerted through inhibiting IL-6-dependent central mechanisms in the CNS.…”

The Adenosinergic Signaling: A Complex but Promising Therapeutic Target for Alzheimer’s Disease

“…In neuronal cells, adenosine regulates survival and neurotransmitter release ( Cunha et al, 2008 ). In glial cells, it is involved in the control of differentiation ( Coppi et al, 2013 , 2015 ), reactivity ( Newell et al, 2015 ; Madeira et al, 2016 ; Liu et al, 2018 ), proliferation ( George et al, 2015 ), and neurotransmitter uptake ( Matos et al, 2012a , b , 2013 ; Cristóvão-Ferreira et al, 2013 ). The role of the physiological increased adenosine tone has been interpreted as involved in neuronal homeostasis, representing a sort of link between energy metabolism and neuronal excitability.…”