基于STAT3信号通路探讨艾司洛尔对脓毒症大鼠急性肝损伤的保护作用

目的探讨艾司洛尔(ES)对脓毒症大鼠急性肝损伤的保护作用及相关信号通路。方法48只雄性SPF级大鼠随机分为假手术(Sham)组、盲肠结扎穿孔(CLP+NS)组和艾司洛尔干预(CLP+ES)组(每组16只)。Sham组采用盲肠探查术,CLP+NS组、CLP+ES组采用CLP法建立脓毒症大鼠模型。CLP+ES组经颈内静脉微量泵入ES稀释液6 h,Sham组和CLP+NS组给予等质量生理盐水。术后6 h、24 h各组分别处死8只大鼠。采用HE染色,观察脓毒症大鼠肝组织形态学变化,生化分析仪检测血清肝功能指标,酶联免疫吸附法(ELISA)检测肝组织中炎性细胞因子水平,Western blot检测肝组织中STAT3信号通路标志蛋白的表达。结果CLP+NS组脓毒症大鼠肝组织炎性细胞浸润明显,而CLP+ES组炎性细胞减少,肝细胞坏死程度好转。术后6 h、24 h,CLP+NS组血清天冬氨酸转氨酶(AST)、丙氨酸转氨酶(ALT)和肝组织匀浆中高迁移率族蛋白B-1(HMGB-1)、白细胞介素-6(IL-6)均升高(P<0.05);而CLP+ES组较CLP+NS组均降低(P<0.05)。术后6 h,与CLP+NS组比较,CLP+ES组脓毒症大鼠肝组织中磷酸化信号转导和转录激活因子3(p-STAT3)表达水平明显下降(P<0.05),细胞因子信号转导抑制因子3(SOCS3)表达明显上升(P<0.05)。术后24 h,CLP+ES组上述蛋白表达与CLP+NS组比较差异无统计学意义(P>0.05)。结论艾司洛尔通过抑制STAT3信号通路,抑制炎性细胞因子释放,从而发挥对脓毒症大鼠急性肝损伤的保护作用。     

Cardiomyocyte function after burn injury and lipopolysaccharide exposure: single-cell contraction analysis and cytokine secretion profile

A component of multiorgan dysfunction in burned patients is heart failure. Burn trauma induces cytokine synthesis of interleukin (IL) 1beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) which can negatively impact cardiac function. Infectious complications are common following severe burn injury. We hypothesized that burn injury and lipopolysaccharide (LPS) exposure independently influence peak cardiomyocyte contraction and cytokine secretion. Rats underwent a full-thickness 30% total body surface area scald or sham burn. At 1, 6, 12, and 24 h after burn, cardiomyocytes were isolated and incubated with increasing LPS doses. Peak sarcomere shortening and contractile velocity parameters were recorded using a variable-rate video camera with sarcomere length detection software. Supernatants were assayed for IL-1beta, IL-6, and TNF-alpha by ELISA. Peak sarcomere shortening was decreased in the burn group at 1, 6, 12, and 24 h after burn. IL-1beta, IL-6, and TNF-alpha levels were increased in cardiomyocytes isolated 1 h after burn compared with sham controls, but returned to sham levels at 6, 12, and 24 h after burn. LPS exposure caused dose-dependent decreases in sarcomere shortening in sham and burn animals. LPS exposure did not produce increased cardiomyocyte cytokine expression. Burn injury diminished peak sarcomere shortening. Whereas exposure to LPS did not have an effect on cardiomyocyte cytokine expression, LPS significantly inhibited sarcomere shortening in a dose-dependent fashion. Combined burn and LPS exposure inhibited sarcomere shortening more than each alone. These results demonstrate that LPS exposure and burn injury independently decrease peak cardiac shortening. These decreases did not directly correlate with the levels of cytokines released in response to each stressor.     

Skin lipopolysaccharide-binding protein and IL-1beta production after thermal injury

In response to a burn injury, skin can have an inflammatory response characterized by the production of inflammatory cytokines, recruitment of immune cells, containment of invading organisms, and clearance of noxious substances from the wound. Lipopolysaccharide-binding protein (LBP) is a molecule that is capable of coordinating all 4 functions; we previously found evidence that suggested that LBP is produced within surgical wounds. Because of the central role of LBP in the response to bacterial infection, as well as in the high rate of infection after burn injuries, we sought to determine whether a thermal injury could affect wound LBP production and thereby affect host responses against bacterial infection. Rats were given either a burn or a sham burn and were killed 24, 48, and 72 hours after the injuries. Wound specimens were assayed for bacterial counts and for the presence of LBP, messenger (m)RNA, and interleukin (IL)-1beta mRNA. Wound LBP mRNA was significantly upregulated at 24 hours in the group with burn injuries (P < .05; burn vs sham burn); this was followed by decreases at 48 and 72 hours. Immunohistochemistry showed LBP protein in the epidermis of animals with burns. Bacterial counts increased in the group with burn injuries (P < .05; burn vs sham burn) and continued to rise for 72 hours. IL-1beta mRNA levels were elevated at all time points in the group with burn injuries (P < .05). These results suggest an inverse correlation between burn wound LBP expression and bacterial wound counts. This failure to maintain local LBP production after severe thermal injury despite localized inflammation shown by high IL-1beta levels may predispose local wounds to bacterial invasion.     

E3B1基因在大鼠急性脊髓损伤中的表达变化研究

目的探讨E3BI基因在大鼠急性脊髓损伤中的表达变化及意义。方法Wistar大鼠75只，随机分为脊髓损伤后4、8、12、24h，2、3、7d以及正常对照组和假手术组（又分手术后4、8、12、24h，2、3、7d7个时相点）。采用RT—PCR、Westernblot和免疫组织化学染色法检测E3BI的表达。结果正常对照组、假手术组均检测到了少量E3BI的mRNA和蛋白表达，脊髓损伤组在伤后4h，E3BI的表达显著高于正常对照组和假手术组，于8h达高峰值，2d仍维持在高表达水平，而后开始下降，7d恢复至对照组水平。免疫组化E3BI阳性细胞主要位于神经元。结论急性髓脊损伤后E3BI的过度表达可能是其再生修复障碍的重要因素。     

大鼠脊髓损伤后勿动蛋白受体的动态表达

目的观察大鼠脊髓损伤后勿动蛋白受体(NgR)在脊髓组织中的动态表达变化。方法108 只Sprague-Dawley 大鼠随机分成正常组、假手术组和模型组,每组36 只,其中模型组采用改良Allen 法造模。3 组分别于干预后24 h、3 d、7 d、14 d 处死大鼠,每组9 只,以免疫组化及Western blotting 检测各组大鼠脊髓组织中NgR表达的变化,以荧光定量PCR检测NgR mRNA表达变化。结果正常组、假手术组各时间点NgR表达无明显变化(P>0.05)。模型组在损伤后24 h NgR及其mRNA表达较低,3 d 后下降至最低,7 d 后迅速上升达到高峰,14 d 时有所下降。与正常组比较,模型组在损伤后各时间点,NgR免疫组化及Western blotting蛋白表达差异均有统计学意义(P<0.05);与假手术组比较,模型组在损伤后各时间点,NgR mRNA表达差异均有统计学意义(P<0.01)。结论大鼠脊髓损伤后,NgR及其mRNA表达均在7 d 时上升至峰值,并较长时间保持高水平表达。这可能是造成脊髓损伤后轴突再生困难的重要原因之一。     

Interaction between the innate and adaptive immune systems is required to survive sepsis and control inflammation after injury

Substantial clinical and laboratory research has revealed that major injury causes abnormalities in both the innate and adaptive immune systems. However, the relative importance of each of these systems in the immune dysfunction after injury is poorly understood and difficult to establish by clinical studies alone. Rag1 (-/-) C57BL/6 mice (Rag1), which lack an adoptive immune system, and immune-sufficient wild-type (WT) C57BL/6 mice underwent 25% total body surface area burn injury or sham injury under anesthesia and were subjected to cecal ligation and puncture (CLP) at day 10 postinjury, a time of high CLP mortality in this model. To test the effect of adaptive immune deficiency on inflammatory cytokine production after injury, adaptive cell-depleted splenocytes from sham and burn WT and Rag1 mice were stimulated with LPS, and TNF-alpha and IL-6 production were assayed at days 1 and 7 postinjury. Intracellular expression of TNFalpha and IL-6 by F4/80 macrophages was also assessed on day 7 by intracellular cytokine staining. Finally, Rag1 animals were reconstituted with WT splenocytes, and the effect of such reconstitution on CLP survival and cytokine production was determined. Survival of sham WT animals after CLP was significantly higher (P < 0.01) than survival of burn WT and Rag1 sham and burn animals, all of which had equivalently low survival. Reconstitution of Rag1 animals with WT splenocytes restored CLP survival to WT sham levels. Splenocytes from Rag1 burn mice showed significantly augmented cytokine production when compared with WT burn mice on day 7 (P < 0.05). Reconstitution of Rag1 mice with WT splenocytes at the time of injury returned cytokine production to WT levels. Intracellular cytokine expression in F4/80 macrophages was increased to a similar degree after burn, but not sham burn injury in Rag1, reconstituted Rag1 and WT animals. These studies demonstrate that the adaptive immune system is necessary for protection from polymicrobial sepsis and plays a significant role in regulating the inflammatory response to injury.     

Acute alcohol intoxication potentiates neutrophil-mediated intestinal tissue damage after burn injury

This study examined whether acute alcohol (EtOH) intoxication before burn injury potentiates postburn intestinal tissue damage and whether neutrophils have any role in the damage under those conditions. Male rats ( approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL or with saline and received either approximately 12.5% or approximately 25% total body surface area (TBSA) burn or sham injury. Rats were killed at 4 or 24 h after injury, and various parameters were measured. As compared with sham animals, burn injury alone (regardless of size) resulted in a significant increase in intestinal tissue myeloperoxidase (MPO; an index of neutrophil infiltration) activity and IL-18 levels 4 h after injury. Furthermore, rats receiving 25% TBSA, but not 12.5%, burn exhibited intestine edema. The IL-18 and MPO activity were normalized at 24 h after injury in rats receiving 12.5% TBSA burn, whereas these parameters remained elevated at 24 h in rats with 25% burn. The presence of EtOH in rats at the time of burn injury exacerbated the levels of IL-18, MPO activity, and edema at 4 and 24 h after burn injury. Treatment of rats with anti-IL-18 antibodies or with antineutrophil antiserum prevented the increase in the above parameters after EtOH and burn injury, except that the depletion of neutrophils did not prevent the IL-18 increase. In summary, these findings suggest that acute EtOH intoxication exacerbates postburn intestinal tissue damage after burn injury, and that it is, in part, neutrophil mediated.     

Circadian rhythm of cytokine secretion following thermal injury in mice: implications for burn and trauma research

Although there are many reports of circadian variation in hormone secretion, there are only a few reports on the relationship between circadian rhythm and cytokine production. The aim of the present studies was to investigate whether there is a circadian effect on cytokine production of splenic lymphocytes and adherent splenocytes in mice after burn or sham injury. We selected day 7 after injury for our determinations because we have previously shown day 7 is the time of maximal suppression of T cell IL-2 and IFNgamma production and maximal increase in adherent cell proinflammatory cytokine secretion in this model. IL-2 and TNFalpha were chosen as reference cytokines since the former is known to be produced by T cells and the latter by adherent cells of the innate immune system. The results showed that seven days after sham or thermal injury both T cell IL-2 and adherent cell TNFalpha production were altered by time of injury or time of cell harvest. IL-2 secretion was significantly decreased in burn compared to sham animals when splenocytes were harvested in the morning; the decrease was non-significant when splenocytes were harvested in the afternoon. TNFalpha secretion was significantly increased in burn vs. sham adherent cells only when injury took place in the morning. The observed circadian variations in cytokine production could have a significant effect on cytokine levels measured in clinical and animal studies of injury and may explain some of the reported discrepancies among these studies.