ACE2、TMPRSS2表达与小鼠COVID-19易感年龄及潜在靶器官关系的探讨

Study on the relationship between the expression of ACE2 and TMPRSS2 and the susceptible age and potential target organs of COVID-19 in mice

目的通过检测血管紧张素转换酶2(ACE2)、跨膜丝氨酸蛋白酶2(TMPRSS2)在小鼠不同年龄阶段(新生期、幼龄期、成年期和老龄期)及不同组织(肺、小肠和心脏)中基因和蛋白的表达水平,探讨小鼠新型冠状病毒肺炎(COVID-19)的易感年龄与潜在靶器官。方法借助生物信息学分析网站(Uniprot)分析ACE2、TMPRSS2在不同物种间保守性;RT-qPCR检测小鼠不同年龄组和不同组织中ACE2、TMPRSS2 mRNA表达水平;Western blot检测小鼠不同年龄组与不同组织中ACE2、TMPRSS2蛋白表达水平。结果①人、小鼠间ACE2同源性达82.1%、TMPRSS2同源性达78.4%;②与新生组比较,幼龄组、成年组和老龄组小鼠肺和小肠组织中ACE2、TMPRSS2 mRNA表达水平均升高(P<0.05);与新生组比较,幼龄组和成年组小鼠心脏组织中ACE2、TMPRSS2 mRNA表达水平升高(P<0.05),而老龄组的表达水平下降(P<0.05);③同龄组小鼠肺、小肠和心脏组织中ACE2、TMPRSS2 mRNA表达水平差异有统计学意义(P<0.05),且在肺组织中表达水平最高;④ACE2与TMPRSS2蛋白表达水平变化与mRNA具有一致性。结论随着年龄增长,小鼠肺和小肠组织中ACE2、TMPRSS2表达也随之增加,这可能意味着高龄是小鼠乃至人感染新型冠状肺炎病毒(SARS-CoV-2)的独立危险因素之一;此外,同一年龄组小鼠肺组织中ACE2、TMPRSS2的高表达提示了肺部可能是SARS-CoV-2入侵机体的主要靶器官。

Objective In this study,we detected angiotensin-converting enzyme 2(ACE2)and transmembrane protease,serine 2(TMPRSS2)expression of different ages(newborn,juvenile stage,adulthood and aged mice)and different tissues(lung,heart and small intestine)in mice to reveal the potential age and target organ that were susceptible to corona virus disease 2019(COVID-19)infection.Methods The conservatism of TMPRSS2 and ACE2 among different species was analyzed by online bioinformatics analysis website(Uniprot).Real-time Quantitative PCR was used to analyze relative expression of ACE2 and TMPRSS2 mRNA at different ages and different tissues in mice.Western blot was used to analyze relative expression of ACE2 and TMPRSS2 protein at different ages and different tissues in mice.Results①The homology of ACE2 between human and mice was 82.1%,and the homology of TMPRSS2 was 78.4%;②Compared with 1-3 day old(newborn group)mice,the expression levels of ACE2 and TMPRSS2 mRNA in lung and small intestine tissues of 1-month old(young group),3-month old(adult group)and 18-month old(old group)mice increased(P<0.05);compared with newborn mice,ACE2 and TMPRSS2 mRNA expression in heart tissues of young and adult mice increased(P<0.05),and TMPRSS2 and ACE2 mRNA expression in elderly group decreased(P<0.05);③Differences in ACE2 and TMPRSS2 mRNA expression levels in different tissues of mice of the same age group were statistically significant,and the highest expression levels were in lung tissue(P<0.05);④The tendency of ACE2 and TMPRSS2 protein and gene expression was consistent.Conclusion With the increase of age,the expression of ACE2 and TMPRSS2 in lung and small intestine of mice also increased,which may mean that advanced age is one of the independent risk factors for infection of Severe Acute Respiratory Syndrome Coronavirus 2(SARS-CoV-2)in mice and even humans.In addition,the high expression of ACE2 and TMPRSS2 in the lung tissue of the same age mice group may suggest that the lung is the main target organ for SARS-CoV-2 invasion.