PNEC和GABA在肺神经内分泌肿瘤中的作用

Role of PNEC and GABA in pulmonary neuroendocrine tumors

目的探讨肺神经内分泌细胞(PNEC)和γ-氨基丁酸(GABA)在肺神经内分泌肿瘤(PNET)患者中的作用。方法收集2018年10月-2022年1月解放军总医院第八医学中心呼吸与危重症医学部胸外科收治的29例PNET患者的病理标本,采用HE染色观察形态学特征,免疫组织化学染色观察突触素(Syn)、嗜铬粒蛋白A(CgA)、CD56、Ki-67、CD86和CD163的表达水平,双抗体免疫荧光共染检测不同类型PNET中降钙素基因相关肽(CGRP)和谷氨酸脱羧酶(GAD)65/67的表达情况,并分析GAD65/67阳性PNEC与巨噬细胞极化的相关性。结果HE染色结果显示,4种类型的PNET组织均具有神经内分泌特征——玫瑰花样结构和器官嵌套或栅栏状图案,但各有差异;有丝分裂细胞占比由低到高为典型类癌(TC)、不典型类癌(AC)、大细胞神经内分泌癌(LCNEC)、小细胞肺癌(SCLC)。免疫组织化学染色结果显示,类癌(TC和AC)的Syn、CgA阳性表达率及Syn、CgA、CD56阳性程度均明显高于LCNEC和SCLC(P<0.05)。4类PNET的Ki-67指数分别为:TC<5%,AC5%~20%,LCNEC和SCLC均>75%。类癌的PNEC数量明显高于LCNEC、SCLC和瘤旁组织(P<0.05);LCNEC和SCLC的PNEC数量与瘤旁组织比较差异无统计学意义(P>0.05)。免疫荧光染色结果显示,95%的PNEC共表达GAD65/67;类癌GAD65/67阳性细胞数明显增多于LCNEC、SCLC和瘤旁组织(P<0.05);LCNEC和SCLC的GAD65/67阳性细胞数与瘤旁组织比较差异无统计学意义(P>0.05)。免疫组织化学染色结果还显示,瘤旁组织中CD86阳性M1巨噬细胞明显多于CD163阳性M2巨噬细胞(P<0.05);而在AC、LCNEC和SCLC中,M2巨噬细胞均明显多于M1巨噬细胞(P<0.01)。相关性分析显示,PNET中GAD65/67阳性PNEC细胞数与肿瘤间质中CD163阳性M2巨噬细胞数呈负相关(r=-0.6336,P=0.0174)。结论PNEC是肺组织中GABA的主要来源,在肺中发挥免疫调节作用,可能参与PNET的进展。

Objective To investigate the role of pulmonary neuroendocrine cells(PNEC)andγ‐aminobutyric acid(GABA)in patients with pulmonary neuroendocrine tumors(PNET).Methods The pathological specimens of 29 cases of PNET treated in the eighth Medical Center of Chinese PLA General Hospital from October 2018 to January 2022 were collected.The morphological characteristics were observed by HE staining,and the expression levels of synaptophysin(Syn),chromogranin A(CgA),CD56,Ki-67,CD86 and CD163 were observed by immunohistochemical staining.Calcitonin gene-related peptide(CGRP)and glutamic acid decarboxylase(GAD)65/67 in different types of PNETs were detected by double antibody immunofluorescence co-staining,and the correlation between GAD65/67 positive PNEC and macrophage polarization was analyzed.Results The results of HE staining showed that all four types of PNET tissues had neuroendocrine(NE)characteristics:rosette structure and organ nesting or palisade pattern,but they were different,and the proportion of mitotic cells from low to high was typical carcinoid(TC),atypical carcinoid(AC),large cell neuroendocrine carcinoma(LCNEC)and small cell lung cancer(SCLC).The results of immunohistochemical staining showed that the positive expression rate of Syn and CgA and the positive degree of Syn,CgA and CD56 in carcinoid(TC and AC)were significantly higher than those in LCNEC and SCLC(P<0.05).The Ki-67 indices of the four types of PNET are:TC<5%,AC 5%-20%,LCNEC and SCLC>75%respectively.The number of PNEC in carcinoid was significantly higher than that in LCNEC,SCLC and paratumoral tissues(P<0.05),but there was no significant difference in the number of PNEC between LCNEC and SCLC and para-tumor tissues(P>0.05).The results of immunofluorescence staining showed that the number of GAD65/67 positive cells co-expressing GAD65/67 in 95%PNEC was significantly higher than that in LCNEC,SCLC and para-tumor tissues(P<0.05),but there was no significant difference between LCNEC and SCLC GAD65/67 positive cells and para-tumor tissues(P>0.05).The results of immunohistochemical staining also showed that the number of CD86 positive M1 macrophages was significantly higher than that of CD163 positive M2 macrophages in para-tumor tissues(P<0.05),while M2 macrophages were significantly more than M1 macrophages in AC,LCNEC and SCLC(P<0.01).Correlation analysis showed that the number of GAD65/67 positive PNEC cells in PNET was negatively correlated with the number of CD163 positive M2 macrophages in tumor stroma(r=-0.6336,P=0.0174).Conclusions PNEC is the main source of GABA in lung tissue and plays an immunomodulatory role in the lung,which may be involved in the progression of PNET.