SARS-CoV-2受体基因Ace2和Axl在小鼠多种组织中定位与表达

Expressions and localizations of SARS-CoV-2receptor genes Ace2and Axl in multiple tissues of mice

目的采用原位杂交技术分析正常生理、病毒感染、细菌感染条件下介导SARS-CoV-2进入细胞的受体基因Ace2、Axl在小鼠多种组织中的定位及表达情况,为COVID-19相关研究提供理论依据。方法21只雄性C57BL/6小鼠,其中3只经麻醉、心脏灌注后获取骨骼肌、心、肝、脑、肺、肾、舌、胃、小肠、大肠、皮肤、鼻腔组织,采用原位杂交技术检测Ace2、Axl mRNA定位及表达情况。其余18只小鼠分为病毒感染组、细菌感染组、对照组各6只,病毒感染组分别于第1、3、5天腹腔注射1g/L Poly(I:C)0.2mg,制备病毒感染小鼠模型;细菌感染组分别于第1、3、5天腹腔注射0.1g/L脂多糖0.02mg,制备细菌感染小鼠模型;对照组注射等体积PBS。于第6天(末次注射后24h)对3组小鼠麻醉、心脏灌注后获取各部位组织,采用原位杂交技术检测Ace2、Axl mRNA定位及表达情况。结果Ace2mRNA在骨骼肌、胃、肝脏、大脑皮层组织无表达,在胆管细胞及肺、大肠组织低表达,在鼻腔上皮、肾脏、心脏、舌、皮肤、小肠上皮组织及脑室周围神经前体细胞高表达;Axl mRNA几乎在所有被检测组织中均高表达。细菌感染组心脏组织Ace2mRNA阳性细胞数[(733±107)个/mm^(2)]高于病毒感染组[(369±99)个/mm^(2)]、对照组[(320±107)个/mm^(2)](P<0.05),病毒感染组与对照组比较差异无统计学意义(P>0.05);细菌感染组心脏、骨骼肌组织Axl mRNA阳性细胞数[(2026±255)、(530±65)个/mm^(2)]均高于病毒感染组[(933±112)、(431±50)个/mm^(2)]、对照组[(687±76)、(333±40)个/mm^(2)](P<0.05),病毒感染组均高于对照组(P<0.05);3组小肠组织Ace2、Axl mRNA阳性细胞平均光密度值及肺、肝脏组织Axl mRNA阳性细胞数比较差异均无统计学意义(P>0.05)。结论小鼠Ace2主要表达于心脏、毛囊、肾脏、舌、小肠等组织,Axl广泛表达于各种组织;细菌感染时心脏组织Ace2、Axl及骨骼肌组织Axl表达上调,病毒感染时心脏、骨骼肌组织Axl表达上调。

Objective To investigate the expressions and localizations of SARS-CoV-2receptor genes Ace2and Axl in multiple organs and tissues of mice under normal status,viral infection and bacterial inflammation by in situ hybridization(ISH),and to provide novel insights into the researches on COVID-19.Methods Three from 21male C57BL/6mice were obtained the skeletal muscle,heart,liver,brain,lung,kidney,tongue,stomach,large intestine,small intestine,skin and nasal cavity tissue after heart perfusion under anesthesia,and their expressions and localizations of Ace2and Axl mRNAs were detected by ISH.The other 18mice were divided into viral infection group,bacterial inflammation group and control group,with 6mice in each group.By day 1,3,and 5,viral infection group was intraperitonelly injected with 0.2mg of 1g/L Poly(I:C)to prepare viral infection models,bacterial inflammation group was intraperitonelly injected with 0.02mg of 0.1g/L lipopolysaccharide to prepare bacterial inflammation models,and control group was injected with equal volume of PBS.The mice were sacrificed by day 6(24hafter final injection)to harvest tissues of each organ,and the expressions and localizations of Ace2and Axl mRNA were detected by ISH.Results Ace2mRNA was not detected in the skeletal muscle,stomach,liver and brain neurons,while it was lowly expressed in the bile duct,lung and large intestine,and was highly expressed in the nasal epithelium,kidney,heart,tongue,skin,small intestinal epithelium and neural progenitor cells.Axl mRNA was highly expressed in almost all tissues.The number of Ace2mRNA positive cells in the heart tissue was larger in bacterial inflammation group[(733±107)/mm^(2)]than that in viral infection group[(369±99)/mm^(2)]and control group[(320±107)/mm^(2)](P<0.05),and showed no significant difference between viral inflammation group and control group(P>0.05).The numbers of Axl mRNA positive cells in the heart and skeletal muscle tissues were larger in bacterial inflammation group[(2026±255),(530±65)/mm^(2)]than those in viral infection group[(933±112),(431±50)/mm^(2)]and control group[(687±76),(333±40)/mm^(2)](P<0.05),and higher in viral infection group than those in control group(P<0.05).There were no significant differences in the average optical densities of Ace2and Axl mRNA in small instestine as well as the numbers of Axl mRNA positive cells in the lung and liver among three groups(P>0.05).Conclusions Ace2is mainly expressed in the heart,hair follicle,kidney,tongue and small intestine,and Axl is broadly expressed in multiple tissues.Bacterial infection leads to an increase of Ace2and Axl in the heart and Axl in the skeletal muscle tissues,while viral infection upregulates the Axl expression in the heart and skeletal muscle tissues.