Natarajan Ramesh, Salloum Fadi N, Fisher Bernard J, Ownby Evan D, Kukreja Rakesh C, Fowler Alpha A
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Virginia Commonwealth University, PO Box 980050, Richmond, VA 23298-0050, USA.
Am J Physiol Heart Circ Physiol. 2007 Sep;293(3):H1571-80. doi: 10.1152/ajpheart.00291.2007. Epub 2007 Jun 1.
Emerging research suggests that oxidant-driven transcription of key cytokine/chemokine networks within the myocardium plays a crucial role in producing ischemia-reperfusion (I/R) injury. We recently showed that activation of hypoxia-inducible factor-1 (HIF-1) attenuated cardiac I/R injury. Diminished injury in these prior studies was associated with significant reductions in circulating interleukin-8 levels, suggesting that HIF-1 may play an important role in modulating postischemic cardiac inflammation. In the current study, we examined the role of HIF-1 activation in modulating proinflammatory chemokine [macrophage inflammatory protein (MIP)-2, cytokine-induced neutrophil chemoattractant factor (KC), and lipopolysaccharide-induced CXC chemokine (LIX)] and adhesion molecule [intercellular adhesion molecule (ICAM)-1] expression in murine cardiomyocytes in vitro (HL-1 cell line) and in intact murine hearts following in vivo I/R injury. Our results show that HIF-1 activation induced both pharmacologically by the prolyl hydroxylase inhibitor dimethyloxallyl glycine and via small-interfering RNA (siRNA)-mediated prolyl-4 hydroxylase-2 (P4HA2) gene silencing significantly attenuated tumor necrosis factor-alpha-induced chemokine (KC and LIX) and ICAM-1 expression in cardiomyocytes. In vivo, postischemic hearts obtained from animals receiving the P4HA2 siRNA (HIF-1 activation) exhibited significantly reduced CXC chemokine (MIP-2, KC, and LIX), CC chemokine (monocyte chemoattractant protein-1), and ICAM-1 expression when compared with postischemic hearts from either saline I/R controls or postischemic hearts from animals receiving a nontargeting control siRNA (no HIF-1 activation). Diminished chemokine and adhesion molecule expression in HIF-1-activated postischemic hearts was associated with significantly reduced polymorphonuclear leukocyte infiltration and myocardial infarct size (>60% reduction P4HA2 siRNA I/R vs. saline I/R, P < 0.001, n = 6). In conclusion, these results demonstrate for the first time that HIF-1 activation following infusion of siRNA to P4HA2 plays a key role in modulating I/R-associated cardiac inflammatory responses.
新出现的研究表明，心肌内关键细胞因子/趋化因子网络的氧化应激驱动转录在产生缺血再灌注（I/R）损伤中起关键作用。我们最近发现，缺氧诱导因子-1（HIF-1）的激活可减轻心脏I/R损伤。在这些先前的研究中，损伤减轻与循环白细胞介素-8水平显著降低有关，这表明HIF-1可能在调节缺血后心脏炎症中起重要作用。在本研究中，我们研究了HIF-1激活在体外（HL-1细胞系）小鼠心肌细胞以及体内I/R损伤后完整小鼠心脏中调节促炎趋化因子[巨噬细胞炎性蛋白（MIP）-2、细胞因子诱导的中性粒细胞趋化因子（KC）和脂多糖诱导的CXC趋化因子（LIX）]和黏附分子[细胞间黏附分子（ICAM）-1]表达中的作用。我们的结果表明，脯氨酰羟化酶抑制剂二甲基草酰甘氨酸药理学诱导的HIF-1激活以及通过小干扰RNA（siRNA）介导的脯氨酰-4羟化酶-2（P4HA2）基因沉默均显著减轻了肿瘤坏死因子-α诱导的心肌细胞趋化因子（KC和LIX）和ICAM-1表达。在体内，与接受生理盐水I/R对照的缺血后心脏或接受非靶向对照siRNA（无HIF-1激活）的动物的缺血后心脏相比，接受P4HA2 siRNA（HIF-1激活）的动物的缺血后心脏中CXC趋化因子（MIP-2、KC和LIX）及CC趋化因子（单核细胞趋化蛋白-1）和ICAM-1表达显著降低。HIF-1激活的缺血后心脏中趋化因子和黏附分子表达降低与多形核白细胞浸润和心肌梗死面积显著减少有关（P4HA2 siRNA I/R组与生理盐水I/R组相比减少>60%，P<0.001，n=6）。总之，这些结果首次证明，向P4HA2输注siRNA后HIF-1激活在调节I/R相关的心脏炎症反应中起关键作用。
