BACKGROUND Interleukin-6 (IL-6) is consistently increased in the digital lamellae in different studies of sepsis-related laminitis (SRL). IL-6 signalling through the gp130 receptor activates similar signalling (i.e. mTORC1-related signalling) previously reported to be activated in models of endocrinopathic laminitis. OBJECTIVES To assess the activation state of signalling proteins downstream of IL-6/gp130 receptor complex activation in an experimental model of SRL. STUDY DESIGN Randomised experimental study. METHODS Lamellar phospho-(P) protein concentrations downstream of the IL-6/gp130 receptors were assessed in the oligofructose (OF) model of SRL. Fifteen Standardbred horses were administered water (CON, n = 8) or oligofructose (OF, n = 7) via a nasogastric tube. At 12 h post-OF/water administration, one randomly assigned forelimb was exposed to continuous digital hypothermia (CDH) by placement in ice water (ICE, maintained at <7°C); the other forelimb was maintained at ambient temperature (AMB). Lamellar tissue samples were collected after 24 h of CDH from both ICE and AMB forelimbs and immediately snap-frozen. Lamellar proteins of interest were assessed by immunoblotting and immunofluorescence. RESULTS Immunoblotting revealed increase (P<0.05) in the phosphorylation states of Akt (Ser 473), RPS6 (Ser235/236), RPS6 (Ser240/244), STAT3 (Ser727) and STAT3 (Tyr705) in lamellar tissue from OF-treated animals (AMB OF vs. AMB CON limbs); CDH resulted in decreased (P<0.05) lamellar concentrations of phosphorylated Akt, p70S6K, RPS6 (235/236), RPS6 (240/244) and STAT3 (S727) in OF-treated animals (AMB OF vs. ICE OF). Immunofluorescence showed that activated/phosphorylated forms of RPS6 and STAT3 were primarily localised to lamellar epithelial cells. MAIN LIMITATIONS The nature, sequence and timing of sub-cellular events in this experimental model may differ from those that accompany naturally occurring sepsis. CONCLUSIONS There were increased lamellar concentrations of activated signalling proteins downstream of the IL-6/Gp130 receptor complex in OF-treated horses; CDH inhibited this activation for the majority of the proteins assessed. These results demonstrate similar lamellar signalling (e.g. mTORC1-related signalling) and, therefore, possible therapeutic targets occurring in sepsis-related laminitis as previously reported in models of endocrinopathic laminitis.

中文翻译：

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指体温过低对马败血症相关椎板炎中与 IL-6/gp130 信号传导相关的层状事件的影响。

背景 在脓毒症相关椎板炎 (SRL) 的不同研究中，白细胞介素 6 (IL-6) 在指板层中持续增加。通过 gp130 受体的 IL-6 信号传导激活了先前报道的在内分泌性椎板炎模型中被激活的类似信号传导（即 mTORC1 相关信号传导）。目的 评估 SRL 实验模型中 IL-6/gp130 受体复合物激活下游信号蛋白的激活状态。研究设计 随机实验研究。方法 在 SRL 的低聚果糖 (OF) 模型中评估 IL-6/gp130 受体下游的层状磷酸 (P) 蛋白浓度。通过鼻胃管给 15 匹标准种马喂水（CON，n = 8）或低聚果糖（OF，n = 7）。在 OF/水给药后 12 小时，一个随机分配的前肢通过置于冰水（ICE，维持在 <7°C）中而暴露于连续数字低温（CDH）；另一前肢保持在环境温度（AMB）。在 24 小时 CDH 后从 ICE 和 AMB 前肢收集层状组织样本并立即速冻。通过免疫印迹和免疫荧光评估感兴趣的层状蛋白。结果 免疫印迹显示来自 OF 处理的层状组织中 Akt (Ser 473)、RPS6 (Ser235/236)、RPS6 (Ser240/244)、STAT3 (Ser727) 和 STAT3 (Tyr705) 的磷酸化状态增加 (P<0.05)动物（AMB OF 与 AMB CON 肢体）；CDH 导致 OF 处理的动物（AMB OF 与 ICE OF）中磷酸化 Akt、p70S6K、RPS6 (235/236)、RPS6 (240/244) 和 STAT3 (S727) 的层状浓度降低 (P<0.05)。免疫荧光显示 RPS6 和 STAT3 的活化/磷酸化形式主要定位于层状上皮细胞。主要限制 本实验模型中亚细胞事件的性质、顺序和时间可能与自然发生的脓毒症不同。结论 在 OF 处理的马中，IL-6/Gp130 受体复合物下游的活化信号蛋白的层状浓度增加。对于大多数评估的蛋白质，CDH 抑制了这种激活。这些结果证明了类似的层状信号传导（例如 mTORC1 相关信号传导），因此，如先前在内分泌病性椎板炎模型中报道的那样，脓毒症相关性椎板炎中可能存在治疗靶点。