新型冠状病毒感染相关蛋白ACE2和TMPRSS2在人结膜组织中的表达及意义

Distribution of COVID-19 transmission-related receptors ACE2 and TMPRSS2 in human conjunctival tissue and its significance

目的探讨新型冠状病毒肺炎(COVID-19)病毒感染相关蛋白血管紧张素转换酶2(ACE2)和跨膜丝氨酸蛋白酶2(TMPRSS2)在人眼部结膜组织中的表达及其临床意义。方法收集2019年6月至2020年6月于西安市人民医院眼科手术切除的人体结膜组织标本50例,包括正常结膜组织10例、结膜乳头状瘤组织15例、结膜色素痣组织15例和结膜囊肿10例,并收集10例因外伤摘除眼球的角膜组织作为对照。采用免疫组织化学法对不同眼表组织标本中ACE2和TMPRSS2阳性表达进行定位,并对其表达强度进行比较。结果ACE2和TMPRSS2均表达于正常结膜上皮细胞、结膜乳头状瘤上皮细胞、结膜色素痣上皮细胞和结膜囊肿囊壁细胞中,ACE2主要表达于结膜上皮的表层细胞和中间层细胞,在基底层细胞和杯状细胞不表达,TMPRSS2表达于全层细胞,二者在结膜组织中的阳性表达率均为100%;ACE2和TMPRSS2在正常结膜组织、结膜乳头状瘤、结膜色素痣和结膜囊肿中的表达强度比较,差异均无统计学意义(均P>0.05);ACE2和TMPRSS2在角膜组织中均为弱阳性表达,二者在不同结膜组织中中度阳性和强阳性表达例数增多。ACE2和TMPRSS2在正常结膜组织、结膜乳头状瘤、结膜色素痣和结膜囊肿中不同强度等级表达例数与角膜组织比较,差异均有统计学意义(ACE2:Z=-3.473、-4.183、-3.970、-3.873,均P<0.01;TMPRSS2:Z=-4.119、-4.472、-4.443、-4.147,均P<0.001)。结论COVID-19病毒感染相关受体蛋白ACE2和TMPRSS2表达于眼表结膜组织中,为COVID-19经眼表的感染途径提供了组织学证据。

Objective To investigate the expression of coronavirus disease 2019(COVID-19)transmission-related receptors angiotensin-converting enzyme 2(ACE2)and transmembrane serine protease 2(TMPRSS2)in human conjunctival tissue and its clinical significance.Methods Fifty human conjunctival tissue specimens from 50 patients including 10 normal conjunctival tissues,15 conjunctival papilloma tissues,15 conjunctival nevus tissues and 10 conjunctival cyst tissues were collected from June 2019 to June 2020 at Xi'an People's Hospital.Ten corneal tissue samples from 10 patients with eyes removed due to trauma were collected as control.The distribution of ACE2 and TMPRSS2 in different corneal tissues was detected by the immunohistochemistry.The expression of ACE2 and TMPRSS2 was scored and compared.Reuse of the human samples and the research protocol was approved by an Ethics Committee of Xi'an People's Hospital(No.20190022).Written informed consent was obtained from each patient.Results ACE2 and TMPRSS2 were both expressed in normal conjunctival epithelium,epithelial cells in conjunctiva papilloma and conjunctival nevus,and cells in conjunctiva cyst wall.ACE2 was mainly distributed in the superficial and intermediate cells of conjunctival epithelium,but not in the basal cells and goblet cells.TMPRSS2 was found in different layers of cells.The positive expression rates of ACE2 and TMPRSS2 in conjunctiva were both 100%.There was no significant difference in the expression intensity of ACE2 and TMPRSS2 among normal conjunctival tissue,conjunctival papilloma,conjunctival nevus and conjunctival cyst(all at P>0.05).Weakly expressed in corneal tissues,ACE2 and TMPRSS2 were more moderately and strongly expressed in conjunctival tissues.There were significant differences in the number of differently graded ACE2 and TMPRSS2 expression between normal conjunctival tissues,conjunctival papilloma,conjunctival nevus,conjunctival cyst and corneal tissues(ACE2:Z=-3.473,-4.183,-3.970,-3.873,all at P<0.01;TMPRSS2:Z=-4.119,-4.472,-4.443,-4.147,all at P<0.001).Conclusions COVID-19 transmission-related receptors ACE2 and TMPRSS2 are expressed in human conjunctival tissue,which provides organological evidence for ocular surface transmission of COVID-19.