WISP1激活内质网应激促进肺泡Ⅱ型上皮细胞铁死亡加重脓毒症肺损伤

脓毒症肺损伤死亡率高，已成为临床亟待解决的重要问题，但发病机制尚未完全阐明。申请人前期研究发现WISP1在脓毒症小鼠肺组织中表达水平显著升高，WISP1中和抗体有效改善小鼠肺损伤程度、降低死亡率，但其下游信号通路的机制不明。预实验提示WISP1激活肺泡Ⅱ型上皮细胞（AECⅡ）内质网应激。据此提出假说：脓毒症中AECⅡ WISP1表达水平上升，导致PERK-ATF4-CHOP途径介导内质网应激，后者调节铁转运蛋白和转铁蛋白表达，破坏细胞内铁离子稳态，通过Fenton反应途径，促进AECⅡ铁死亡，死亡细胞从基底膜脱落，破坏上皮细胞屏障功能，加重脓毒症肺损伤。本研究拟采用盲肠结扎穿孔小鼠模型，应用特异性AECⅡ WISP1基因敲除小鼠和构建WISP1过表达/敲除载体等手段从动物与细胞水平证明上述假说，有望从WISP1激活内质网应激促进铁死亡角度阐释脓毒症肺损伤的新机制，为临床防治提供新靶点。

The mortality of sepsis induced lung injury is as high as 50%, which has become an important clinical problem to be solved urgently, but its pathogenesis has not been fully elucidated. Our previous studies found that the expression level of WISP1 in the lung tissue of septic mice was significantly increased. WISP1 neutralizing antibody effectively improve the degree of lung injury and reduce mortality. However, the mechanism of WISP1 downstream signaling pathway is still unknown. Preliminary experimental results suggest that WISP1 activates the endoplasmic reticulum stress of primary alveolar type Ⅱ epithelial cells dependent on the PERK-ATF4 pathway. Based on this, we put forward the hypothesis that under sepsis, the expression level of AECⅡ WISP1 increases, leading to endoplasmic reticulum stress mediated by the PERK-ATF4-CHOP pathway. The latter regulates the expression of ferroportin and transferrin, destroying the intracellular iron ion homeostasis. AEC Ⅱ ferropotosis is promoted through the Fenton reaction pathway, leading to the shedding of AEC Ⅱ from the basement membrane, destroying the barrier function of epithelial cells, and aggravating sepsis induced lung injury. The study intends to use a cecal ligation and perforation mouse model, using specific alveolar type Ⅱ epithelial cell WISP1 gene knockout mice and CRISPR/Cas 9 technology to construct WISP1 overexpression/knockout vectors and other methods to verify the above hypothesis from animal and cellular level. This topic explains the molecular mechanism of sepsis induced lung injury from the perspective of WISP1 activating endoplasmic reticulum stress and then promoting ferropotosis. This research project provides a new target for clinical prevention and treatment.