Abstract Introduction Endothelial cells play a central role in the pathophysiology of sepsis-associated acute kidney injury (SA-AKI), yet we have limited understanding of the markers of microvascular-specific response. We therefore employed a translational approach integrating spatially resolved transcriptomics in a mouse SA-AKI model with validation in human kidney tissues and plasma, aiming to define the molecular signature of the endothelial response to SA-AKI in mice and in human patients. Methods In this post hoc analysis of prospectively collected data, we identified sepsis-associated target mRNAs and validated their expression via RT-qPCR in distinct renal microvascular compartments isolated by laser microdissection (LMD) from both cecal ligation and puncture (CLP) mice and post-mortem kidney biopsies of SA-AKI patients. Additionally, we measured the corresponding circulating proteins in plasma from two patient cohorts with sepsis and SA-AKI: one consisting of patients presenting to the emergency department, and the other of patients with severe sepsis requiring organ support in the ICU. Results We identified several differentially expressed genes in the renal microvasculature following sepsis, including Mt1 , Mt2 , Saa3, Hp , C3 , Sparc , Mmp8 , and Chil3 . Whole-organ samples from CLP mice also showed increased expression in the liver and lung. Except for SPARC , all genes were similarly upregulated in human kidney biopsies from SA-AKI patients. Circulating protein levels were elevated in sepsis and SA-AKI patients compared to controls; however, only CHI3L1 and MMP8 showed significantly higher levels in SA-AKI versus sepsis across both early and advanced stages. Conclusion Our findings reveal markers of the microvascular response to sepsis, which include increased levels of HP, C3, Chil3/CHI3L1, and MMP8 , both at the transcriptomic level in mouse and human kidney microvasculature and at the protein level in circulating plasma of SA-AKI patients. The upregulation of these markers was shared across multiple organs and may reflect widespread endothelial activation contributing to sepsis pathophysiology.
Aart et al. (Tue,) studied this question.