Chen Lee-Wei, Chen Pei-Hsuan, Chang Wei-Jung, Wang Jyh-Seng, Karin Michael, Hsu Ching-Mei
Department of Surgery, Kaohsiung Veterans General Hospital, National Yang-Ming Medical University, Taipei, Taiwan.
Crit Care Med. 2007 May;35(5):1332-40. doi: 10.1097/01.CCM.0000261891.30360.F0.
The molecular mechanism of major burn-induced gut damage is not clear. This study is to determine whether IkappaB-kinase (IKK)/nuclear factor-kappaB signaling in intestinal mucosa maintains gut function through the regulation of the c-Jun NH2-terminal kinase (JNK) and p38 phosphorylation.
Prospective, experimental study.
Research laboratory at a university hospital.
Thermal injury models in mice.
Conditional intestinal epithelial cell IKKbeta knockout (Vil-Cre/Ikkbeta(F/Delta) mice and control (Ikkbeta(F/Delta) mice were subjected to 30% total body surface area third-degree burn. JNK inhibitor (SP600125) or p38 inhibitor (SB203580) was given to mice immediately after burn injury.
Thermal injury induced a significant increase of intestinal permeability, nuclear factor-kappaB DNA-binding activity, phosphorylated JNK, phosphorylated p38, and caspase 3 expression of intestinal mucosa in Vil-Cre/Ikkbeta(F/Delta) mice compared with those of Ikkbeta(F/Delta) mice. BCL-xL and cellular FLICE inhibitory protein, but not GADD45beta (growth arrest and DNA damage-inducing protein beta), cellular inhibitor of apoptosis 1, Bfl-1, or TRAIL, messenger RNA expression was significantly decreased in Vil-Cre/Ikkbeta(F/Delta) mice compared with that of Ikkbeta(F/Delta) mice. SP600125 decreased intestinal permeability and increased phosphorylated p38 and tumor necrosis factor receptor-associated factor 2 expression of intestinal mucosa in Vil-Cre/Ikkbeta(F/Delta) mice. SB203580 treatment enhanced thermal injury-induced gut damage in Vil-Cre/Ikkbeta(F/Delta) mice.
Thermal injury induces nuclear factor-kappaB activation of intestinal mucosa and IKK protects intestinal mucosa from thermal injury-induced gut damage. IKK blocks caspase 3 expression by up-regulating BCL-xL and cellular FLICE inhibitory protein expression. IKK inhibits JNK and p38 but not p44/42 phosphorylation of intestinal mucosa. JNK inhibition increases p38 and tumor necrosis factor receptor-associated factor 2 expression and decreases thermal injury-induced gut damage. Taken together with the enhanced thermal injury-induced gut damage by p38 inhibition, we conclude that IKK maintains gut function by inhibiting JNK phosphorylation, which suppresses p38 phosphorylation and induces gut damage.
严重烧伤所致肠道损伤的分子机制尚不清楚。本研究旨在确定肠黏膜中的IκB激酶（IKK）/核因子κB信号通路是否通过调节c-Jun氨基末端激酶（JNK）和p38磷酸化来维持肠道功能。
前瞻性实验研究。
大学医院的研究实验室。
小鼠热损伤模型。
对条件性肠上皮细胞IKKβ基因敲除小鼠（Vil-Cre/Ikkβ（F/Δ）小鼠）和对照小鼠（Ikkβ（F/Δ）小鼠）进行30%体表面积的三度烧伤。烧伤后立即给小鼠注射JNK抑制剂（SP600125）或p38抑制剂（SB203580）。
与Ikkβ（F/Δ）小鼠相比，热损伤导致Vil-Cre/Ikkβ（F/Δ）小鼠肠黏膜通透性显著增加、核因子κB DNA结合活性增强、磷酸化JNK、磷酸化p38及半胱天冬酶3表达增加。与Ikkβ（F/Δ）小鼠相比，Vil-Cre/Ikkβ（F/Δ）小鼠中BCL-xL和细胞FLICE抑制蛋白的信使核糖核酸表达显著降低，但生长停滞和DNA损伤诱导蛋白β（GADD45β）、凋亡抑制蛋白-1、Bfl-1或肿瘤坏死因子相关凋亡诱导配体（TRAIL）的信使核糖核酸表达未显著降低。SP600125降低了Vil-Cre/Ikkβ（F/Δ）小鼠的肠黏膜通透性，并增加了其肠黏膜中磷酸化p38和肿瘤坏死因子受体相关因子2的表达。SB203580治疗增强了Vil-Cre/Ikkβ（F/Δ）小鼠热损伤诱导的肠道损伤。
热损伤诱导肠黏膜核因子κB激活，IKK可保护肠黏膜免受热损伤诱导的肠道损伤。IKK通过上调BCL-xL和细胞FLICE抑制蛋白表达来阻断半胱天冬酶3的表达。IKK抑制肠黏膜的JNK和p38磷酸化，但不抑制p44/42磷酸化。抑制JNK可增加p38和肿瘤坏死因子受体相关因子2的表达，并减轻热损伤诱导的肠道损伤。结合p38抑制增强热损伤诱导的肠道损伤这一结果，我们得出结论，IKK通过抑制JNK磷酸化来维持肠道功能，而JNK磷酸化抑制可抑制p38磷酸化并诱导肠道损伤。
