Effect of eosinphil granule proteins on beta-adrenergic receptor

研究了嗜酸性粒细胞过氧化物酶(EPO)+过氧化氢(H_2O_2)对β-肾上腺素能受体数量的影响。用Sephadex G-50和CM-Sepharose柱层析从高嗜酸性粒细胞综合征患者的嗜酸性粒细胞中提取人EPO。豚鼠肺膜部分先与EPO预孵育，再与H_2O_2孵育2小时。结合实验测定β-肾上腺素能受体的数量。3~10U/mlEPO和10 U/ml4&gt；M H_2O_2可显著减少β-肾上腺素能受体的数目，10U/mlEPO和10~(-6)&gt；M H_2O_2也能显著减少β-受体数目。用促红细胞生成素(EPO)预先孵育S 49细胞15分钟，再用10℃~(-4)M H_2O_2孵育45分钟。细胞离心，悬浮于含黄嘌呤的培养液中，用10^-lt；-4&gt；M异丙肾上腺素刺激产生胞内环磷酸腺苷(CAMP)。胞内环磷酸腺苷产生wap…0.1-1U/mlEPO和10^~(-1)~(-3)~(-GT)H_2O_2对细胞的抑制作用更明显，且抑制程度与EPO浓度有关。1U/mlFPO和10^lt；-3&gt；M H_2O_2对cAMP生成的抑制作用为91%，EPO对cAMP的生成也有抑制作用。EPO或H_2O_2单独作用不能抑制cAMP的产生。EPO+H_2O_2体系对S49细胞的β-肾上腺素能受体数目无明显影响，但使其对异丙肾上腺素的亲和力降低。EPO+H_2O_2对10^-lt；-5&gt；M forsklin刺激的cAMP产生也有抑制作用，但异丙肾上腺素刺激的抑制程度大于Forsklin刺激。主要碱性蛋白和嗜酸性粒细胞阳离子蛋白对β-肾上腺素能受体数目和cAMP产生均无明显抑制作用。较少

Effect of eosinophil peroxidase (EPO) + H_2O_2 on beta-adrenergic receptor number was studied. Human EPO was obtained from eosinophils of hypereosinophilic syndrome patients by sequential chromatograph on Sephadex G-50 and CM-Sepharose column. Guinea pig lung membrane fraction was first preincubated with EPO, then incubated with H_2O_2 for 2 hours. The number of beta-adrenergic receptor was measured by binding assay. The number of beta adrenergic receptor was significantly decreased by 3-10 U/ml EPO and 10^<-4>M H_2O_2. Beta-receptor number was also decreased by 10 U/ml EPO and 10^<-6>M H_2O_2.Next effect of EPC on beta-adrenergic receptor-adenylate cyclase system was studied. S 49 cells were preincubated with EPO for 15 minutes, and then incubated with 10^<-4>M H_2O_2 for 45 minutes. The cells were centrifuged, resuspended in culture medium including xanthine, then stimulated by 10^<-4>M isoproterenol to generate intracellular cyclic AMP (CAMP). Intracellular cyclic AMP production wap … More significantly inhibited by the pretreatment with 0.1-1 U/ml EPO and 10^<-3>M H_2O_2, and the degree of inhibition was EPO concentration dependent. CAMP production was inhibited by 91 % by pretreatment with 1 U/ml FPO and 10^<-3>M H_2O_2. CAMP production was also inhibited when 10^<-4>M or 10^<-5>M H_2O_2 was applied with EPO. EPO or H_2O_2 alone did not inhidited CAMP production. The number of beta-adrener gic receptor on S49 cells did not change by EPO + H_2O_2 system, however, the affinity of beta-adrenergic receptor to isoproterenol was decreased. CAMP production stimulated by 10^<-5>M forskolin was also inhibited by EPO + H_2O_2, however, the degree of inhibition was greater in isoproterenol stimulation than in forskolin stimulation.Major basic protein and eosinophil cationic protein did not have significant suppressive effects either on beta-adrenergic receptor number or on CAMP production.These results suggest that EPO is one of the factors that induce betaadrenergic hyporesponsiveness in patients with bronchial asthma. Less