异常腺苷A2A受体信号为选择性保护氧诱导视网膜病变的新干预靶点

Retinopathy of prematurity (ROP) is caused by oxygen-induced damage to developing retinal vasculatures and has become a major cause of childhood blindness in many parts of the world. Inspired by the clinical observation of the reduced severity of ROP in premature infants after caffeine treatment for sleep apnea, we recently made a novel discovery that genetic and pharmacological inactivation of the adenosine A2A receptor (A2AR) (by non-selective adenosine antagonist caffeine or A2AR antagonist KW6002) attenuated oxygen-induced retinopathy (OIR) without affecting normal development of retinal vascularization. Based on these findings, we proposed that abnormal retinal A2AR signaling may be selectively targeted for treating ROP without server unwanted effect on normal retinal development. Equipped with a series of cell-type specific A2AR knockout models with selective deletion of A2ARs in bone marrow, astrocytes, macrophages and retinal neurons and coupled with mouse OIR model and rat 50/10 oxygen oscillation model of ROP, we will first establish the critical role of the A2AR signaling in bone marrow cells, astrocytes, microglial cells and retinal neurons as well as the molecular signaling pathway (cAMP-CXCR4/SDF-1 and cAMP-Csk-IFN-γ) in differentially controlling normal developmental retinal vasculatures and oxygen-induced pathological angiogenesis and retinopathy. Then, we will identify the effective therapeutic window (i.e. hyperoxic or hypoxic phases) as well as their cellular bases (retinal neuronal apoptosis and astrocytic function) for caffeine and KW6002 to confer protection against OIR. Lastly, we will critically evaluate combined caffeine-KW6002 and KW6002-anti-VEGF treatment to identify therapeutic strategies with maximal synergistic effect on ROP pathological with minimal effect on physiological development of retinal vasculatures. The information derived from this study will not only elucidate the cellular and molecular mechanism underlying selective control pathological angiogenesis by targeting abnormal A2AR signaling, but also provide the proof-of-principle evidence to translate the novel caffeine- and A2AR antagonist-based therapies for prevention and treatment of ROP.

早产儿视网膜病变(ROP)以视网膜血管病理增生为特征，是儿童致盲的主要原因。临床显示：早产儿接受腺苷受体非特异拮抗剂咖啡因治疗呼吸暂停随访视网膜血管病变减弱，我们研究发现：咖啡因治疗或腺苷A2A受体失活减轻氧诱导视网膜病变(OIR)，不影响正常血管发育。我们提出异常A2A受体信号为抑制视网膜病理性血管生成而不干扰血管正常发育的新靶点。本研究利用星形胶质、巨噬细胞，视网膜神经元等细胞特异A2A受体敲除和小鼠OIR/大鼠50-10%氧模型，阐明：1.咖啡因和A2A受体拮抗剂KW6002抑制视网膜病理血管增生不影响正常血管发育的细胞和分子机制；2.咖啡因和KW6002对OIR保护作用有效时间窗及高氧和低氧阶段的细胞机制；3.通过KW6002和咖啡因/抗VEGF联用，阐明A2A受体信号和非A2A受体信号协同调控ROP的分子基础。结合咖啡因临床安全性，确立异常A2A受体信号新干预靶点有转化医学前景。

早产儿视网膜病变(ROP)以视网膜血管病理增生为特征，是儿童致盲的主要原因。临床观察显示：早产儿接受腺苷受体非特异拮抗剂咖啡因治疗呼吸暂停随访发现视网膜血管病变减弱；我们前期研究发现：咖啡因治疗或腺苷A2A受体敲除减轻氧诱导视网膜病变(OIR)，但不影响正常血管发育。本课题解决的关键科学问题是：腺苷A2A受体选择性调控氧诱导视网膜血管病变的细胞和分子机制。利用细胞特异（星形胶质、巨噬、内皮和视网膜神经元）A2A受体敲除，结合单细胞测序，shRNAi，药理学和小鼠OIR模型，我们阐明：1.咖啡因和A2A受体拮抗剂KW6002主要作用于高氧期以抑制视网膜血管病变不影响正常血管发育；2. 在高氧期，咖啡因/KW6002对OIR的保护主要通过逆转高氧对视网膜细胞增殖的抑制实现；在低氧期，与增加内皮尖端细胞数和星形胶质细胞完整性相关；3. 神经细胞和小胶质细胞(而非星型胶质细胞)A2A受体敲除减轻缺氧期病理血管增生；单细胞测序显示A2A受体作用于神经细胞逆转高氧诱导的视网膜细胞基因变化；因此神经/胶质对血管内皮细胞的交互作用是调控视网膜血管病变的重要机制;4.在高氧期A2A受体阻断可通过调控TGF-β -ID1信号通路逆转高氧对细胞增殖的抑制作用，增加内皮尖端细胞而保护血管；5. KW6002和咖啡因和内皮尖端细胞关键分子ADM（但非VEGF）协同调控OIR的血管病变；6.高氧诱导的视网膜损伤，OPA1功能异常导致的视网膜神经节细胞损伤和脑神经退行性疾病具有相似病理生理机制（线粒体功能损伤）并同受A2A受体阻断保护。综上，（不同于针对缺氧期抗VEGF）我们确立A2A受体信号作用高氧期实现治疗ROP早期干预思路和靶点，阐明A2A受体通过逆转高氧对视网膜细胞增殖的抑制和神经/胶质对血管内皮细胞的间接调控的新颖机制。结合咖啡因（已治疗新生儿呼吸暂停）和KW6002（2019年获US FDA批准用于治疗帕金森氏病）的临床安全性， A2A受体拮抗剂用于治疗ROP具有极大的转化医学前景。