Induced hypothemia as new therapy for extensive severe burn injuries: Effects of hypothermia on the blood cytokine level inburned rats

诱导低温疗法已被证明对包括烧伤在内的严重损伤有保护作用。然而，这种冷疗法在临床应用中仍存在争议，并且细胞因子激活对低温反应的变化尚未有详细的研究。本研究旨在探讨低温对热损伤早期细胞因子激活的影响。方法：机械通气麻醉大鼠24只，随机分为4组：1组不给药，不给热损伤（n=6，对照组）；第2组（n=6）在制备后给予假热损伤。第三组（n=6）热损伤后维持常温。第4组（n=6）热伤后进行30℃的亚低温治疗。第3组和第4组大鼠进行体表面积30%的iii度烫伤。在假烧伤或烫伤后2小时采血，测定细胞因子水平。采用酶联免疫吸附法测定肿瘤坏死因子-α (TNF-α)、白细胞介素-1β (IL-1β)、白细胞介素-6 （IL-6）、白细胞介素-8 （IL-8）和白细胞介素-10 （IL-10）的活性。结果：热损伤组（3、4组）IL-β、IL-8、IL-10、IL-1β、IL-8均显著升高，但4组低于3组。结论：本研究证实热损伤可诱导IL-β、IL-8、IL-10升高，但低温组IL-β、IL-8、IL-10升高幅度较小。上述结果提示，低温对烧伤早期具有保护作用，对热损伤的治疗有较大的临床效益。

The induced hypothermia has been shown to be protective in the severe injuries including the burn. However, this cold therapy remained controversial in the application on the clinical cases and the changes in cytokine activation in response to hypothermia have not been studied in detail previously. The aim of this study is to evaluate the effects or hypothermia on the activation of cytokines during the early phase or thermal injury.METHODS: Twenty four anesthetized rats under mechanically controlled ventilation were divided into four groups: In the group l, no preparations and no thermal injury were given (n=6, control). In the group 2 (n=6), the sham thermal injury was given after the preparations. In the group 3 (n=6), rats were maintained at normothermia after the thermal injury. In the group 4 (n=6), mild hypothermia (30℃) was applied after the thermal injury. In the groups 3 and 4, rats were submitted to a III-degree scald burn of 30% total body surface area. Bloods were collected at 2 hours after either the sham or scald burn for the determination of the cytokine level. The tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), and Interleukin-10 (IL-10) activities were assessed by the enzyme-linked immunosorbent assay.RESULTS: Thermal injuries (Groups 3 and 4) induced marked elevations of IL-β, IL-8, IL-10, IL-1β and IL-8 but they were less in Group 4 than in Group 3.CONCLUSION: This study confirmed that thermal injury induces increases in IL-β, IL-8, IL-10, but their increases were significantly smaller in the hypothermic group. These findings suggest that the induced hypothermia was protective in early burn phase and that the hypothermia is or great clinical benefit in the treatment or thermal injury.