Wan Song, Yim Anthony P C, Wong Chun Kwok, Arifi Ahmed A, Yip Johnson H Y, Ng Calvin S H, Waye Mary M Y, Lam Christopher W K
Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, PR China.
Int J Cardiol. 2002 Dec;86(2-3):265-72. doi: 10.1016/s0167-5273(02)00331-5.
Proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, and IL-8 have been implicated in myocardial injury following cardiopulmonary bypass (CPB). However, little evidence is currently available to directly confirm such a relationship. We have previously documented that a newly discovered 'four and a half LIM-only protein 2' (FHL2) is exclusively expressed in myofibres. We hypothesized that the upregulation of FHL2 is proportional to the degree of myocardial injury and investigated the myocardial expression of FHL2 together with these cytokine messenger RNAs (mRNAs) during clinical CPB.
Intermittent hypothermic blood cardioplegia was used in all patients. Atrial myocardial biopsies were obtained immediately at the onset and at the end of CPB in 33 consecutive patients undergoing valvular or coronary artery surgery. TNF-alpha, IL-6, and IL-8 mRNA expressions in these myocardial samples were determined by semi-quantitative reverse transcription-polymerase chain reaction. Myocardial FHL2 expression was determined by Western blot analysis. Serum levels of the MB isoenzyme of creatine kinase (CK-MB) and cardiac troponin-I (cTnI) before surgery and 24 h after the end of CPB were also measured.
The duration of aortic crossclamping and CPB was 70+/-33 and 99+/-37 min, respectively. No elevated myocardial TNF-alpha mRNA expression was found after CPB. IL-6 mRNA expressions were detected in 14 pairs of the myocardial biopsies and were elevated in 11 (33%) post-CPB biopsies. Similarly, IL-8 mRNA expressions were detected in 19 pairs of samples and were elevated in 14 (42%) post-CPB biopsies. Among the 17 pairs of biopsies with positive FHL2 expression, FHL2 levels were increased in 11 (33%) post-CPB samples. Moreover, the elevated FHL2 expression was associated with an increase in IL-6 (P=0.018) and IL-8 (P=0.024) mRNA expression after CPB. Postoperative CK-MB and cTnI levels were significantly higher in patients with myocardial FHL2 expressions than those without (CK-MB, 13.5+/-2.3 vs. 6.5+/-0.8 ng/ml, P=0.022; cTnI, 10.7+/-2.0 vs. 3.5+/-0.6 ng/ml, P=0.0013).
Our findings demonstrate for the first time that both IL-6 and IL-8 mRNAs are upregulated in human cardiac myocytes following CPB and these cytokines may be involved in myocardial ischemia-reperfusion injury, as reflected by their association with an increased expression of FHL2.
促炎细胞因子，如肿瘤坏死因子α（TNF-α）、白细胞介素（IL）-6和IL-8，被认为与体外循环（CPB）后的心肌损伤有关。然而，目前几乎没有直接证据证实这种关系。我们之前记录了一种新发现的“仅含四个半LIM结构域蛋白2”（FHL2）仅在肌纤维中表达。我们假设FHL2的上调与心肌损伤程度成正比，并在临床CPB期间研究了FHL2与这些细胞因子信使核糖核酸（mRNA）的心肌表达情况。
所有患者均采用间歇性低温血液停搏液。对33例连续接受瓣膜或冠状动脉手术的患者，在CPB开始时和结束时立即取心房心肌活检组织。通过半定量逆转录-聚合酶链反应测定这些心肌样本中TNF-α、IL-6和IL-8 mRNA的表达。通过蛋白质印迹分析测定心肌FHL2的表达。还测量了术前和CPB结束后24小时血清肌酸激酶MB同工酶（CK-MB）和心肌肌钙蛋白I（cTnI）的水平。
主动脉阻断和CPB的持续时间分别为70±33分钟和99±37分钟。CPB后未发现心肌TNF-α mRNA表达升高。在14对心肌活检组织中检测到IL-6 mRNA表达，其中11对（33%）CPB后活检组织中IL-6 mRNA表达升高。同样，在19对样本中检测到IL-8 mRNA表达，其中14对（42%）CPB后活检组织中IL-8 mRNA表达升高。在17对FHL2表达阳性的活检组织中，11对（33%）CPB后样本中FHL2水平升高。此外，CPB后FHL2表达升高与IL-6（P=0.018）和IL-8（P=0.024）mRNA表达增加有关。心肌FHL2表达阳性的患者术后CK-MB和cTnI水平显著高于无心肌FHL2表达的患者（CK-MB，13.5±2.3对6.5±0.8 ng/ml，P=0.022；cTnI，10.7±2.0对3.5±0.6 ng/ml，P=0.0013）。
我们的研究结果首次表明，CPB后人心脏心肌细胞中IL-6和IL-8 mRNA均上调，这些细胞因子可能参与心肌缺血-再灌注损伤，这一点通过它们与FHL2表达增加的相关性得到反映。
