Selective antagonism of adenosine A2A receptor reduces hypobaric hypoxia-induced neuroinflammation by inhibiting cGAS-STING pathway.

Abstract

High altitude with insufficient oxygen supply poses a great threat to public health. Short- or long-term hypobaric hypoxia (HY) exposure significantly impairs cognitive function. Adenosine receptors with four subtypes participate in the pathogenesis of multiple neurodegenerative diseases. However, the functions of adenosine receptors in HY-induced cognitive impairment are poorly explored. A mouse model of HY-induced cognitive impairment was established using a hypobaric chamber to simulated hypoxia conditions equal to an altitude of 7000 m for 14 days. The levels of adenosine receptors (ADORA1, ADORA2A, ADORA2B and ADORA3) in the hippocampus of cognitively impaired mice was detected by Quantitative Real-time Polymerase Chain Reaction (qPCR) and Western blot. The ADORA2A antagonist KW6002 was administered from day 4 to day 14 of HY exposure. Neurobehavioral function assessments, histopathological staining, evans blue extravasation and transmission electron microscopy were used to evaluate the therapeutic effects of KW6002 in vivo. RNA-seq, qPCR, ELISA, immunofluorescence, and western blots were performed to investigate the underlying mechanism of adenosine A2A receptor in HY-induced cognitive impairment. Adenosine A2A receptor was uniquely upregulated after HY exposure, while the other three subtypes (ADORA1, ADORA2B and ADORA3) were barely influenced. Selective antagonism of ADORA2A by KW6002 strongly attenuated mice neurological deficits and histopathological injuries. Furthermore, KW6002 enhanced the integrity of blood-brain barrier (BBB), mitigated oxidative stress and neuroinflammation. KW6002 potently inhibited the production of endogenous cAMP and cascading mitochondrial protein levels of EPAC1 and VDAC1, which alleviated the release of the mtDNA to cytoplasm via mitochondrial permeability transition pore (MPTP). Less cytosolic mtDNA accumulation after KW6002 treatment attenuated HY-induced activation of cGAS-STING inflammatory signaling pathway. ADORA2A activation mediates HY cognitive impairment, which is achieved by activating EPAC1 and VDAC1 to mediate mtDNA release and cGAS-STING signaling pathway to drive neuroinflammation cascade.