中华急诊医学杂志  2022, Vol. 31 Issue (5): 628-635   DOI: 10.3760/cma.j.issn.1671-0282.2022.05.012
一氧化碳释放分子2调控T淋巴细胞分化介导抗炎保护失血性休克大鼠肠屏障
牛庆晟1 , 张瑞2 , 陈磊1 , 王晓红3     
1. 宁夏医科大学临床医学院,银川 750004;
2. 宁夏颅脑疾病重点实验室,银川 750004;
3. 宁夏医科大学总医院重症医学科,银川 750004
摘要: 目的 探讨一氧化碳释放分子2(carbon monoxide-releasing molecule-2, CORM-2)调控T淋巴细胞的分化介导抗炎保护失血性休克大鼠肠屏障。方法 56只健康雄性SD大鼠按照随机数字表法分为假手术组、休克组、二甲基亚砜组(dimethyl sulfoxide, DMSO)、灭活型一氧化碳释放分子2组(inactive carbon monoxide-releasing molecule-2, iCORM-2)、CORM-2 2 mg/kg组、CORM-2 4 mg/kg组及CORM-2 6 mg/kg共7组,每组8只。采用Wiggers改良法制备失血性休克大鼠模型,CORM-2各剂量组和iCORM-2组于制备休克模型前即刻腹腔注射不同剂量CORM-2和6 mg/kg iCORM-2,DMSO组腹腔注射与iCORM-2等量的2%DMSO,休克组和假手术组不给予药物干预。各组大鼠记录置管后或休克后不同时相平均动脉压变化。各组大鼠造模成功后23 h采用荧光素异硫氰酸酯(fliorescein isothiocyanate, FITC)-葡聚糖作为渗透性标记物测试肠壁通透性,并留取回肠组织观察肠道病理形态。免疫组化观察大鼠肠黏膜淋巴细胞转录因子T-bet、Foxp3的表达,Western Blot检测大鼠肠黏膜组织干扰素-γ(interferon-γ, IFN-γ)、白介素10(interleukin-10, IL-10)和转化生长因子-β(transforming growth factor-β, TGF-β)的表达。正态分布计量资料多组间均数比较采用单因素方差分析,非正态分布数据采用Kruskal Wallis秩和检验。结果 与假手术组相比,休克组、DMSO组和iCORM-2组血清中FITC-葡聚糖浓度明显增加(均P < 0.05);与休克其余各组比较,CORM-2各剂量组血清中FITC-葡聚糖浓度均减低(均P < 0.05)。病理学改变显示休克组、DMSO组和iCORM-2组大鼠回肠组织损伤明显;CORM-2干预可减轻休克大鼠回肠黏膜损伤,且CORM-2 4 mg/kg组和CORM-2 6 mg/kg组回肠结构更完整。休克组和DMSO组肠黏膜淋巴细胞T-bet抗原表达较假手术组升高(均P < 0.05);CORM-2各剂量组T-bet抗原表达较休克组降低(均P < 0.05)。CORM-2 2 mg/kg组、CORM-2 4 mg/kg组及iCORM-2组Foxp3抗原表达较休克组和DMSO组均减低(均P < 0.05),但CORM-2 6 mg/kg组与休克组或DMSO组比较差异无统计学意义(均P > 0.05)。与假手术组相比,休克组IFN-γ表达升高(P < 0.05),IL-10和TGF-β表达未见差异(均P > 0.05);与休克组相比,CORM-2各剂量组IL-10蛋白表达升高(均P < 0.05),其中CORM-2 4 mg/kg组和CORM-2 6 mg/kg组TGF-β表达上调(均P < 0.05),但仅CORM-2 6 mg/kg组较休克组IFN-γ表达下调(P < 0.05)。结论 CORM-2可抑制1型辅助性T细胞的活化,降低炎症因子,增加抗炎因子,减轻休克缺血肠壁炎症,保护肠屏障。
关键词: 一氧化碳释放分子2    休克        淋巴细胞    炎症    
Carbon monoxide releasing molecule 2 exhibits anti-inflammatory effects by regulating T lymphocyte differentiation to protect intestinal barrier in rats with hemorrhagic shock
Niu Qingsheng1 , Zhang Rui2 , Chen Lei1 , Wang Xiaohong3     
1. School of Clinical Medicine, Ningxia Medical University, Yinchuan 750004, China;
2. Ningxia Key Laboratory of Craniocerebral Diseases, Yinchuan 750004, China;
3. Department of Intensive Care Unit, General Hospital of Ningxia Medical University, Yinchuan 750004, China
Abstract: Objective To investigate the protective effect of carbon monoxide releasing molecule 2 (CORM-2) on intestinal barrier by regulating the differentiation of T lymphocytes in rats with hemorrhagic shock. Methods Healthy male Sprague-Dawley rats (n=56) were randomly (random number) divided into the sham operation group, shock group, dimethyl sulfoxide (DMSO) control group, inactivated carbon monoxide release molecule-2 (iCORM-2) pretreatment group and three pretreatment CORM-2 with the doses of 2, 4 and 6 mg/kg separately. The hemorrhagic shock was induced with the use of a modified Wiggers model. Rats in the CORM-2 group and iCORM-2 group were intraperitoneally injected with CORM-2 with the doses of 2, 4 and 6 mg/kg and 6 mg/kg iCORM-2 instantly before shock induction. Rats in the DMSO group received intraperitoneal administration of 2% DMSO with the same volume of iCORM-2. Rats in the shock group and sham operation group were not pretreated before inducing shock. Mean arterial pressure of each rat was recorded at different phases after catheterization or shock. Twenty-three hours after shock induction, the permeability of intestinal barrier was measured by FITC-dextran flux, and then ileum tissues were harvested to observe histopathologic changes. Immunohistochemistry was used to detect the expression of transcription factors T-bet and Foxp3 of intestinal mucosa in rats, and the expression of interferon-γ (IFN-γ), interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) in intestinal mucosa was measured by Western blot. One-way analysis of variance or Kruskal Wallis rank sum test was used to compare the difference among groups for normal or non-normal distributed data. Results Compared with the sham operation group, serum concentrations of FITC-dextran were significantly increased in the shock group, DMSO group and iCORM-2 group (all P < 0.05). The concentrations of FITC-dextran in serum of three CORM-2 pretreatment groups pretreatment were significantly decreased compared with other groups undergoing shock (all P < 0.05). Rats in the shock group, DMSO group and iCORM-2 group showed severe ileum injury. CORM-2 intervention resulted in alleviation of intestinal mucosal injury in rats with shock, and rats in groups pretreatment CORM-2 at the doses of 4 and 6 mg/kg exhibited integrity of anatomic ileac structure. Compared with the sham operation group, T-bet levels of intestinal intraepithelial lymphocytes were increased in shock group and DMSO group (all P < 0.05). Compared with the shock group, levels of T-bet were decreased in intestinal epithelium of three groups pretreatment with CORM-2 at the doses of 2, 4 and 6 mg/kg (all P < 0.05). Foxp3 levels in intestinal intraepithelial lymphocytes of the iCORM-2 group and two groups pretreatment with CORM-2 at the doses of 4 and 6 mg/kg were increased compared with the shock group and DMSO group (all P < 0.05), but there was no significant difference among the shock group, DMSO group and group pretreatment with CORM-2 at 6 mg/kg (all P>0.05). The shock group showed increased expression of IFN-γ (all P < 0.05), but unchangeable expression of IL-10 and TGF-β (all P>0.05) compared with the sham operation group. Compared with the shock group, the expression levels of IL-10 in three groups pretreatment with CORM-2 at the doses of 2, 4 and 6 mg/kg were significantly increased (all P < 0.05), and the expression levels of TGF-β were increased in two groups pretreatment with CORM-2 at the doses of 4 and 6 mg/kg (all P < 0.05). The expression of IFN-γ in group pretreatment with CORM-2 at 6 mg/kg was significantly decreased compared with the shock group (P < 0.05). Conclusions CORM-2 inhibited the activation of type 1 helper T cells to decrease the expression of proinflammatory factors and upregulated the expression of anti-inflammatory factors. Thus, CORM-2 reduced gut inflammation and protected the intestinal barrier.
Key words: Carbon monoxide releasing molecule-2    Shock    Intestine    Lymphocyte    Inflammation    

肠道被认为是休克患者并发肠源性感染及多脏器功能障碍的“发动机”[1]。肠道是人体最大的免疫器官,包括人体70%的免疫细胞,尤其是肠上皮和固有层内具有丰富淋巴细胞[2-3]。近年研究证实肠道缺血-再灌注损伤(ischemia reperfusion injury, IRI)中不仅中性粒细胞等固有免疫细胞参与,淋巴细胞也发挥重要作用,尤其适应性免疫的主要细胞T细胞参与不同疾病模型下多种器官的IRI[4-5]。因此研究肠道IRI中淋巴细胞亚群变化及其调节,对于保护IRI肠屏障,减少全身炎症反应,保护远隔器官,改善休克预后具有重要意义。目前针对肠道IRI缺乏有效的保护手段。外源性一氧化碳释放分子-2(carbon monoxide-releasing molecule-2, CORM-2)是一种携带一氧化碳(carbon monoxide, CO)的新型金属羰基化合物,CO具有抗炎症、抗凋亡、免疫调节等多重效应[6]。本团队前期研究证实CORM-2可减轻休克大鼠肠黏膜机械屏障损伤[7]。本研究拟建立失血性休克大鼠模型,CORM-2预处理大鼠,观察大鼠肠黏膜上皮1型辅助性T(T helper 1, Th1)细胞与调节性T(regulatory T, Treg)细胞及相关炎症因子的表达,探讨CO对失血性休克大鼠肠黏膜屏障的保护作用机制。

1 材料与方法 1.1 实验仪器与试剂

本研究使用鼠恒温实验台(成都泰盟公司,中国)、生物机能实验系统(成都泰盟公司,中国)和高速冷冻离心机(Thermo,美国)。实验试剂包括CORM-2(Sigma,美国)、荧光素异硫氰酸酯(fliorescein isothiocyanate, FITC)-葡聚糖(Sigma,美国)、T-bet兔抗鼠多克隆抗体(Abcam,英国)、Foxp3兔抗鼠多克隆抗体(Abcam,英国)重组抗体、干扰素-γ(interferon-γ, IFN-γ)抗体(Abcam,英国)、白介素10(interleukin, IL-10)多克隆抗体(Thermo,美国)、重组抗转化生长因子-β(transforming growth factor-β, TGF-β)抗体(Abcam,英国)。

1.2 药物制备

CORM-2溶液的制备:1 mg CORM-2粉剂溶于20 μL的DMSO,振荡均匀,加入980 μL的0.9%的生理盐水,振荡均匀,使得DMSO的终体积分数为2%,药物现用现配。iCORM-2溶液配制:将配制好的CORM-2溶液放置37 ℃恒温箱72 h,打开容器盖,避光保存48 h,待药物释放完全后使用。

1.3 失血性休克大鼠模型的建立

SPF级雄性SD大鼠,9~10周龄,体重280~350 g,购自宁夏医科大学动物实验中心,许可证号:SCXK(宁)2020-000-1。大鼠实验前24 h禁食,自由饮水。实验严格遵循宁夏医科大学总医院动物伦理委员会的各项规定(伦理编号2020-841)。本实验采用Wiggers改良法制备失血性休克大鼠模型。1%戊巴比妥钠(40 mg/kg)腹腔注射麻醉大鼠。分别经右颈动脉放置23号PE-50聚乙烯管用于监测平均动脉血压(mean arterial pressure, MAP),经动脉导管三通处放血,经左颈静脉置管用于复苏补液准备。导管均充满肝素生理盐水,并通过压力传感器与数据采集卡连接实时记录数据电脑存盘,记录基础血流动力学数据。动静脉穿刺手术完成后,待大鼠生理参数稳定开始诱导休克。用无菌注射器从右颈动脉导管三通处以0.5 mL/min的速度开始放血, 在10 min内将MAP降到40 mmHg(1 mmHg=0.133 kPa)。通过动脉放血或静脉回输(当MAP > 40 mmHg时放血,MAP < 35 mmHg时回输)以维持实验大鼠MAP在35~40 mmHg间的休克状态2 h,休克模型即建立成功。休克维持2 h后行液体复苏,经静脉导管输注复苏液,复苏液为回输所失的血量并加上1.5倍失血量的林格液,30 min内将MAP升到血压稳定后停止复苏,观察血流动力学稳定30 min。实验结束后,拔除导管观察24 h,记录生存情况。

1.4 实验分组及预处理

56只SPF级雄性SD大鼠采用随机数字表法分为7组,即假手术组、休克组、DMSO组、iCORM-2组、CORM-2 2 mg/kg组、CORM-2 4 mg/kg组和CORM-2 6 mg/kg组,每组8只。假手术组大鼠仅置入相关导管,不进行失血性休克相关建模操作。不同浓度CORM-2组于制作休克模型前即刻腹腔注射2 mg/kg、4 mg/kg及6 mg/kg CORM-2药物。iCORM-2组干预药物浓度为6 mg/kg,于制作休克模型前即刻腹腔注射;DMSO组于制作休克模型前即刻腹腔注射与iCORM-2组等量的2% DMSO溶液。休克组和假手术组不予其他预处理。

1.5 大鼠血流动力学监测

假手术组分别于大鼠颈动脉置管后即刻(即0 h)、1.5 h、2.5 h和3 h记录MAP变化。其余6组大鼠于置管后即刻(或休克前)、置管后1.5 h(或休克后1 h)、置管后2.5 h(或休克后2 h)、置管后3 h(或复苏后)记录MAP的动态变化。

1.6 大鼠肠道通透性的测定

各组术后23 h使用FITC-葡聚糖作为渗透性标记物测试大鼠同一部位肠壁通透性。1%戊巴比妥钠(40 mg/kg)腹腔注射麻醉大鼠,固定于鼠恒温实验台。寻找回盲部,分离结肠与回肠,结扎约4 cm末端回肠的两端,并将400 μL FITC-葡聚糖(25 mg/mL)注射到肠腔中。1 h后留取大鼠血液标本5 mL,离心(12 000 r/min,4 ℃,10 min),将血清(500 μL)与500 μL PBS混合,并通过荧光分光光度计检测大鼠血清内FITC-葡聚糖的荧光强度(激发光波长:488 nm,发射光波长:525 nm),根据标准曲线计算FITC-葡聚糖浓度,进行肠道通透性检测。

1.7 大鼠肠黏膜病理形态学观察

各组术后24 h留取大鼠同一部位回肠组织,4%多聚甲醛溶液固定后,经乙醇脱水、石蜡包埋、切片,苏木精-伊红(HE)染色,光镜下观察肠黏膜形态,并用Chiu 6级评分法对肠黏膜损伤程度进行评价[8]

1.8 免疫组化检测大鼠回肠组织淋巴细胞T-bet和Foxp3转录因子的表达

各组术后24 h留取大鼠同一部位回肠组织,4%多聚甲醛固定。将组织脱蜡并用dd-H2O冲洗。洗涤后,加入1 500~3 000 mL柠檬酸盐缓冲液,在封闭缓冲液中孵育30 min。样品用稀释的一抗缓冲液在4 ℃下孵育过夜,抗T-bet抗体、抗Foxp3抗体稀释比分别为1∶250和1∶150。在洗涤一抗后,加入适量的HRP标记兔抗山羊二级抗体(40 min,室温)。然后用DAB(ZSGB-BIO,中国北京)显色液显示背景。免疫组化结果判定以细胞核中出现棕黄色为阳性,每只大鼠选取3张切片,每张切片随机选取5个视野,显微镜下观察载玻片染色情况。利用ImageProPlus图像分析技术分析靶蛋白的平均吸光度值。

1.9 大鼠回肠组织IFN-γ、IL-10、TGF-β炎症因子水平的表达

各组术后24 h留取大鼠同一部位回肠组织。Western blot检测回肠组织IFN-γ、IL-10、TGF-β蛋白水平。裂解回肠组织提取总蛋白,用BCA法定量后,进行SDS-PAGE电泳并转移至PVDF膜。脱脂奶粉封闭1.5 h,分别加入IFN-γ、IL-10、TGF-β抗体(均1∶1 000稀释),4 ℃孵育过夜,TBST洗膜3次,加入HRP标记山羊抗兔(1∶3 000稀释),室温下孵育1 h,TBST洗膜3次,加入ECL显影,用ImageJ分析软件测定各蛋白条带灰度值;实验重复3次。

1.10 统计学方法

应用SPSS 22.0软件进行统计分析和数据处理。对计量资料数据进行正态性检验及方差齐性检验,服从正态分布的以均数±标准差(x±s)表示,采用单因素方差分析和Student-Newman-Keuls检验;非正态分布的计量资料以中位数(四分位数)[MQ1Q3)]表示,采用Kruskal Wallis秩和检验。组内结果随时间变化采用重复测量的多因素方差分析。以P < 0.05为差异具有统计学意义。

2 结果 2.1 各组大鼠不同时相MAP的变化

休克各组大鼠麻醉后MAP为(101±3)mmHg。大鼠失血(6.5±0.3)mL后MAP降低至(37.0±0.9)mmHg。休克持续2 h后复苏补液,补液后大鼠MAP维持(84±5)mmHg。诱导休克后,休克各组不同时间点血压均低于假手术组(均P < 0.05),且各组休克后不同时相MAP均低于休克前血压(均P < 0.05)。除假手术组之外,其余各组之间置管后3 h(或复苏后)血压差异无统计学意义(均P>0.05)。见图 1表 1

A:休克前;B:诱导休克后1 h;C:诱导休克后2 h;D:复苏后 图 1 休克大鼠不同时相MAP的变化 Fig 1 Changes of MAP at different time points in rats with shock

表 1 各组大鼠不同时相MAP(n=8/组,mmHg,x±s Table 1 Mean arterial pressure of rats in each group at different time points (n=8 per group, mmHg, x±s)
组别 T0 T1 T2 T3 F P
假手术组 101±8 101±8 102±8 103±9 0.118 0.949
休克组 99±15 37±2ab 37±4ab 84±12ab 81.681 < 0.001
DMSO组 102±15 36±2ab 37±3ab 83±9ab 114.247 < 0.001
iCORM-2组 98±12 37±3ab 37±3ab 83±9ab 137.611 < 0.001
CORM-2 2 mg/kg组 100±11 37±2ab 38±3ab 85±11ab 127.514 < 0.001
CORM-2 4 mg/kg组 94±10 36±2ab 38±4ab 78±9ab 133.004 < 0.001
CORM-2 6 mg/kg组 96±10 38±3ab 37±4ab 82±10ab 129.433 < 0.001
F 0.457 339.190 244.197 5.271
P 0.836 < 0.001 < 0.001 < 0.001
注:T0为置管后即刻(或休克前),T1为置管后1.5 h(或休克1 h),T2为置管后2.5 h(或休克2 h),T3为置管后3 h(或复苏后);a为组间不同时间点,与假手术组相比P < 0.05;b为组内不同时相点,与T0比较P < 0.05
2.2 各组大鼠回肠组织通透性测定

表 2所示,与假手术组相比,休克组、DMSO组、iCORM-2组血清中FITC-葡聚糖浓度增高(均P < 0.05),而CORM-2各组,仅2 mg/kg组血清的FITC-葡聚糖浓度增高(P < 0.05),CORM-2其余各组与假手术组比较差异无统计学意义(均P>0.05)。与休克组、iCORM-2组和DMSO组相比,CORM-2各剂量组血清FITC-葡聚糖浓度均降低(均P < 0.05)。CORM-2不同剂量组之间比较,血清FITC-葡聚糖浓度差异无统计学意义(均P>0.05),但CORM-2 6 mg/kg血清中FITC-葡聚糖有降低趋势。

表 2 各组大鼠血清中FITC-葡聚糖浓度及肠黏膜组织Chiu评分的比较(n=8/组,x±s Table 2 Comparison of FITC-dextran concentration in serum and Chiu score in intestinal mucosa of rats in each group (n=8 per group, x±s)
指标 假手术组 休克组 DMSO组 iCORM组 CORM-2 2 mg/kg组 CORM-2 4 mg/kg组 CORM-2 6 mg/kg组 H P
FITC-葡聚糖(μg/mL) 0.020±0.016 5.699±0.438a 4.517±1.571a 5.117±1.519a 0.729±0.396abcd 0.454±0.261bcd 0.220±0.214bcd 27.345 < 0.001
Chiu评分(分) 0.89±0.66 4.43±0.51ad 3.64±1.03a 3.58±0.99a 3.00±1.68ab 2.88±0.92ab 2.58±1.02ab 47.214 < 0.001
注:与假手术组相比,aP < 0.05;与休克组相比,bP < 0.05;与iCORM-2组相比,cP < 0.05;与DMSO组相比,dP < 0.05
2.3 各组大鼠回肠组织病理形态学观察

假手术组大鼠回肠黏膜上皮完整,腺体结构清晰,绒毛排列整齐;休克组大鼠回肠绒毛结构消失,绒毛表面游离,肠上皮细胞出现大量坏死,结构不连续,破坏明显,有大量炎症细胞聚集;CORM-2 4 mg/kg组和6 mg/kg组大鼠回肠上皮细胞少量坏死,绒毛部分节段结构不连续,未见明显水肿,较其他休克组明显改善;见图 2。由表 2可见,与假手术组比,休克各组肠黏膜组织病理Chiu评分均升高(均P < 0.05);与休克组、iCORM-2组和DMSO组相比较,CORM-2不同剂量组Chiu评分均降低(均P < 0.05);但CORM-2各剂量组之间比较,肠黏膜组织病理Chiu评分无差异(均P>0.05)。

图 2 各组大鼠回肠组织病理改变的比较(HE染色,×100) Fig 2 Comparison of histopathological changes of ileum of rats in each group (HE staining, original magnification×100)
2.4 各组大鼠肠黏膜上皮T-bet、Foxp3表达

各组大鼠肠黏膜上皮T-bet、Foxp3表达情况见图 3

箭头所指为细胞核中出现棕黄色,视为阳性细胞 图 3 各组大鼠肠黏膜T-bet、Foxp3表达(免疫组化,放大倍数×400) Fig 3 Expression of T-bet and Foxp3 in intestinal mucosa of rats in each group (immunohistochemistry, original magnification × 400)

与假手术组相比,诱导休克后仅休克组和DMSO组肠黏膜淋巴细胞T-bet抗原表达升高(均P < 0.05);iCORM-2组和CORM-2各剂量组T-bet抗原与假手术组比较差异无统计学意义(均P>0.05),均低于休克组(均P < 0.05);CORM-2各剂量组T-bet抗原表达与iCORM-2组比较差异无统计学意义(均P>0.05)。见图 4

1~7依次为假手术组、休克组、DMSO组、iCORM-2组、CORM-2 2 mg/kg组、CORM-2 4 mg/kg组、CORM-2 6 mg/kg组;与假手术组相比,aP < 0.05;与休克组相比,bP < 0.05;与DMSO组相比,cP < 0.05;与iCORM-2组相比,dP < 0.05 图 4 各组大鼠肠黏膜T-bet、Foxp3抗原阳性表达的平均吸光度值比较 Fig 4 Comparison of average optical density of T-bet and Foxp3 antigen-positive expression in intestinal mucosa of rats in each group

与假手术组比较,休克组、DMSO组和CORM-2 6 mg/kg组肠黏膜淋巴细胞Foxp3抗原表达升高(均P < 0.05);CORM-2 2 mg/kg组、CORM-2 4 mg/kg组及iCORM-2组Foxp3抗原表达较休克组和DMSO组均减低(均P < 0.05),但CORM-2 6 mg/kg组与休克组或DMSO组比较差异无统计学意义(均P>0.05);休克组和DMSO组之间Foxp3抗原表达差异无统计学意义(P>0.05)。见图 4

2.5 各组大鼠回肠组织IFN-γ、TGF-β、IL-10蛋白表达水平比较

与假手术组相比,休克组、DMSO组、iCORM-2组和CORM-2 2 mg/kg组IFN-γ表达升高(均P < 0.05);CORM-2各剂量组中,仅CORM-2 6 mg/kg组较休克组、iCORM-2组和DMSO相比IFN-γ表达明显降低(均P < 0.05)。见图 5

1~7依次为假手术组、休克组、DMSO组、iCORM-2组、CORM-2 2 mg/kg组、CORM-2 4 mg/kg组、CORM-2 6 mg/kg组;与假手术组相比,aP < 0.05;与休克组相比,bP < 0.05;与DMSO组相比,cP < 0.05;与iCORM-2组相比,dP < 0.05 图 5 各组大鼠回肠组织IL-10、IFN-γ、TGF-β蛋白相对表达水平比较 Fig 5 Comparison of expression levels of IL-10, IFN-γ, and TGF-β protein in ileum of rats in each group

与假手术组比较,仅CORM-2各剂量组TGF-β蛋白表达升高(均P < 0.05),其余各组TGF-β蛋白表达与假手术组差异无统计学意义(均P>0.05);CORM-2各剂量组中,4 mg/kg组和6 mg/kg组TGF-β表达高于休克组和DMSO组(均P < 0.05)。见图 5

CORM-2各剂量组IL-10蛋白表达均高于休克组(均P < 0.05),4 mg/kg组和6 mg/kg组IL-10蛋白表达同时高于DMSO组(均P < 0.05)。CORM-2各剂量组中仅6 mg/kg组IL-10蛋白表达较iCORM-2组升高(P < 0.05)。见图 5

3 讨论

休克是由不同原因引起机体有效循环血量减少、微循环灌注不足、细胞代谢紊乱并可引起多器官功能障碍的临床综合征[9]。小肠因其独特的肠绒毛毛细血管袢的分布特点,使之对IRI高度敏感,且肠道是休克时最早损伤、最迟恢复的器官[10]。目前尚缺乏保护肠屏障有效的方法。本研究采用Wiggers改良法建立大鼠失血性休克模型,大鼠维持休克状态120 min, 休克各组MAP均降低,持续至复苏后。休克大鼠回肠黏膜出现柱状细胞与杯状细胞的缺失,绒毛结构消失或排列紊乱,肠上皮大量淋巴细胞浸润。使用FITC-葡聚糖作为渗透标记物检测回肠黏膜组织通透性,结果显示失血性休克大鼠肠黏膜组织通透性增加。以上结果提示失血性休克大鼠肠损伤模型构建成功。

内源性CO是一种气体信使分子, 合适剂量的CO具有抗炎、抗氧化、细胞保护等生理功能[11]。CORM-2是一种新型金属羰基化合物,已被证实在生理条件下能有效地将CO输送到组织中发挥保护作用[6]。本研究使用不同剂量CORM-2干预失血性休克大鼠,结果显示CORM-2干预后休克大鼠回肠黏膜病理损伤减轻,肠黏膜的通透性较休克组降低,证实CORM-2可有效地保护休克大鼠肠黏膜屏障的完整性。其中CORM-2 6 mg/kg对休克大鼠肠黏膜屏障保护作用最强,CORM-2 2 mg/kg的保护作用较弱。

CO保护肠屏障机制尚不清楚。越来越多的证据显示肠道相关淋巴组织是肠IRI的靶标者,也是主动参与者[12]。肠道具有丰富的免疫细胞,淋巴细胞在肠道IRI中发挥重要作用[4-5]。因此,淋巴细胞亚群变化及其调节在保护IRI肠屏障、减少全身炎症反应保护远隔器官功能、改善休克预后中十分关键。本研究探讨CORM-2对休克IRI肠道CD4+T淋巴细胞活化类型及其分泌炎症因子的影响。初始CD4+T细胞根据分泌的细胞因子和功能不同进一步分化为Th1、Th2、Thl7和Treg细胞。多个信号转导子和转录活化子信号通路分子协调CD4+T细胞诱导T-bet表达, 促进Th1细胞的分化[13]。Th1细胞是经典促炎因子,是原生动物的免疫至关重要的一类免疫细胞,可产生IFN-γ[14]。Treg细胞是CD4+T淋巴细胞的另一种辅助性T细胞,表达特征转录因子Foxp3,分泌IL-10、TGF-β等抑制炎症反应[15]。本研究结果发现休克大鼠肠粘膜淋巴细胞T-bet抗原表达升高,同时肠黏膜IFN-γ表达增高,提示休克肠IRI损伤Th1细胞活化,其促炎介质释放可能参与了肠IRI损伤;CORM-2可能抑制Th1细胞活化,减轻了休克大鼠肠黏膜炎症因子如IFN-γ的释放,减轻缺血肠壁损伤;本研究结果与Nikolic等[16]研究基本一致。

值得注意的是,本研究除证实CORM-2能够抑制促炎因子IFN-γ的释放外,还可上调抗炎因子IL-10和TGF-β的表达,提示CORM-2对休克缺血肠壁的炎症损伤具有抗炎效应。Magierowska等[17]研究证实CO通过上调IL-10和TGF-β发挥抗炎效应促进胃溃疡愈合,与本研究结果一致。总之,以上的证据提示CO可抑制促炎Th1细胞活化引起的炎症反应,或通过促进抗炎因子的释放,减轻失血性休克大鼠缺血肠黏膜的过度激活的炎症反应,保护肠道。然而,本结果提示CORM-2并非增加缺血肠黏膜Treg细胞活化,增加抗炎因子IL-10和TGF-β表达,发挥抑制缺血肠壁炎症反应的效应。本研究分析CORM-2促进IL-10和TGF-β抗炎因子的表达并不依赖于Treg的活化,可能是由其他免疫细胞产生,其具体机制尚待阐明。

综上所述,CORM-2可有效保护失血性休克大鼠肠黏膜屏障,抑制Th1促炎细胞的活化,降低IFN-γ促炎因子表达。CORM-2增加IL-10、TGF-β等抗炎因子表达,减轻缺血肠壁炎症,保护肠屏障。

利益冲突  所有作者声明无利益冲突

作者贡献声明  牛庆晟:实验操作、论文撰写;张瑞、陈磊:数据收集及整理、统计学分析;王晓红:研究设计、论文修改

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