双阴性T细胞活化自然杀伤细胞促进小鼠暴发型肝炎的发生发展

Double negative T cells contribute to the outcome of murine fulminant viral hepatitis via promoting natural killer cell activation

目的检测双阴性T(double negative T,DNT)细胞对自然杀伤(natural killer,NK)细胞功 能的影响,初步探讨其在3型鼠肝炎病毒(murine hepatitis vims strain 3,MHV-3)诱导的小鼠暴发型肝炎 (fulminant viral hepatitis,FVH)模型中发挥的作用。方法通过腹腔注射MHV-3感染BALB/cJ小鼠诱 导FVH,尾静脉转移过继FVH小鼠脾脏DNT细胞,观察小鼠生存时间和肝脏组织病理学改变,流式细胞术检测小鼠肝脏NK细胞CD69表达情况。磁珠分选肝脏DNT细胞和NK细胞,共培养24h后,检测NK细胞CD69、胞内干扰素-γ(interferon-γ,IFN-γ)和肿瘤坏死因子-α(tumor necrosis factor,TNF-α)的表 达水平,利用乳酸脱氢酶释放实验检测NK细胞对原代肝细胞的杀伤作用。结果转移过继DNT细胞,FVH小鼠生存时间缩短,在三天内全部死亡。转移过继组小鼠肝脏NK细胞CD69表达比例较对照组显 著升高[(80.60±5.56)%比(4.53±4.82)%,P<0.05]。肝脏DNT细胞和NK细胞以10: 1比例共培养,NK细胞CD69表达比例较NK单独培养显著增加[(23.1±3.7)%比(4. 53±4.82)%<0.05], TNF-α表达水平升高[(8.9 ±2.3)%比(3.0 ±0.2)%,P<0.05],NK细胞对原代肝细胞的杀伤活性明 显增强[(7. 6±0.5)%比(3.7±0.4)%,P<0. 05]。结论DNT细胞可促进NK细胞活化和TNF-α表 达,增强NK细胞对肝细胞的杀伤作用,可能为DNT细胞参与FVH发生发展的机制之一。

Objective To explore the effect of double negative T( DNT) cells on natural killer (NK) cells and its contribution to the pathogenesis of fulminant viral hepatitis( FVH) induced by murine hepatitis virus strain 3 ( MHV-3). Methods The model of FVH was established by intraperitoneal injection of MHV-3 into BALB/cJ mice. Splenic DNT cells were adoptively transferred into BALB/cJ mice with FVH. The expression of CD69 in NK cells was analyzed by flow cytometry. Hepatic DNT cells and NK cells were cocultured for 24 h. The expressions of C 1)69,IFN-γ,and TNF-a were determined by flow cytometry. The cytotoxic capacity of hepatic NK cells against hepatocytes was examined by non-radioactive cytotoxicity assay. Results After adoptive transfer of DNT cells into Balb/cJ mice with FVH,all of the mice died within 3 days. Compared to the control mice,the expression of CD69 in hepatic NK cells of the adoptive mice was increased significantly[ (80. 60 ± 5. 56)% vs. (4.53 ±4.82)%,P <0.05]. Compared to untreated control,the expressions of CD69 and TNF-α in NK cells were remarkably increased,(23. 1 ±3. 7 % ) vs. (4. 53 ±4. 82) %< 0. 05 ;( 8. 9 ± 2. 3 ) % vs. (3. 0 ±0. 2)%,P <0. 05],after coculturing with DNT cells. In addition,the cytotoxic capacity of hepatic NK cells against hepatocytes was enhanced [(7. 6 ± 0. 5 % ) vs. ( 3. 7 ± 0? 4) %,P < 0. 05 ].Conclusion DNT cells could activate NK cells and enhance the production of TNF-α and the cytotoxic capacity of NK cells,which might eventually contribute to the pathogenesis of FVH.