Endotoxin preconditioning as a model to uncover protective pathways in sepsis-induced renal injury

脓毒症引起的急性肾损伤仍然是一个主要的临床问题，没有建立有效的治疗方法， 约会虽然潜在的治疗靶点已被确定并在临床试验中进行了测试，但没有一个靶点 证明是有效的，强调了脓毒症病理生理学的复杂性。我们实验室的工作 确定细胞间通讯的紊乱是复杂病理生理学的主要特征 败血症导致的肾损伤例如，从S1小管到下游S2/S3的病理信号传导 肾小管是脓毒症肾损伤的主要途径。事实上，我们将S1近端肾小管段确定为 过滤内毒素的主要传感器和接收器。S1对内毒素的摄取导致严重的氧化应激 并对下游S2/S3节段造成损害。靶向S1转录组学和组织代谢组学揭示 嘌呤代谢在脓毒症的S1近端小管中显著改变。黄嘌呤催化了这种转变 氧化还原酶是嘌呤降解途径中的关键酶。这种酶的功能是脱氢酶 (XDH)但容易通过巯基氧化或蛋白水解转化为氧化酶（XO 改性XDH的催化作用不产生自由基，而XO是一种强促氧化剂， 产生有害的活性物质。此外，促氧化剂XO分泌到泌尿腔中， 因此可能对下游段造成损害。相反，巨噬细胞中XO的表达可能是 有益的，因为它通过产生活性物质刺激这些细胞的杀菌潜力。 本提案的一个目标是确定XO与XDH在S1和脓毒症中巨噬细胞中的相对作用。 肾脏此外，由于XO/XDH参与嘌呤的最终降解，因此XO/XDH的变化与嘌呤的最终降解有关。 活性不仅会影响活性物质的产生，而且还会对上游的尺寸产生影响。 嘌呤池。本提案的第二个目标是确定嘌呤代谢物的总通量， 它们对脓毒症中嘌呤稳态的贡献。

Sepsis-induced acute kidney injury remains a major clinical problem with no effective therapy established to date. Although potential therapeutic targets have been identified and tested in clinical trials, none of them has proven to be effective, underscoring the complexity of sepsis pathophysiology. Work from our laboratory identified disturbances in cell-cell communication as a major feature underlying the complex pathophysiology of sepsis-induced kidney damage. For example, pathologic signaling from S1 tubules to downstream S2/S3 tubules was a major pathway of renal injury in sepsis. Indeed, we identified the S1 proximal tubular segment as a major sensor and sink for filtered endotoxin. This S1 uptake of endotoxin resulted in severe oxidative stress and damage to downstream S2/S3 segments. Targeted S1 transcriptomics and tissue metabolomics revealed that purine metabolism is markedly altered in septic S1 proximal tubules. This shift is catalyzed by xanthine oxidoreductase, a key enzyme in the purine degradation pathway. This enzyme functions as a dehydrogenase (XDH) in its native form but is readily converted to an oxidase (XO) through sulfhydryl oxidation or proteolytic modification. Whereas catalysis by XDH does not generate free radicals, XO is a strong pro-oxidant that generates deleterious reactive species. Furthermore, the pro-oxidant XO is secreted into the urinary lumen and can therefore cause damage to downstream segments. In contrast, XO expression in macrophages may be beneficial because it stimulates the bactericidal potential of these cells through generation of reactive species. It is one goal of this proposal to establish the relative roles of XO versus XDH in S1 and macrophages in septic kidneys. Moreover, because XO/XDH is involved in the final degradation of purines, the changes in XO/XDH activity will not only affect the generation of reactive species but will also have an upstream impact on the size of purine pools. It is the second goal of this proposal to determine the overall flux of purine metabolites and their contributions to purine homeostasis in sepsis.