Unique Transcriptional Programs Identify Subtypes of AKI

Area of Science:

• Nephrology
• Molecular Biology
• Genomics

Background:

• Current acute kidney injury (AKI) diagnostics rely on serum creatinine and urine output, which lack etiological specificity.
• The distinction between intrinsic kidney injury (iAKI) and volume-depleted AKI (vAKI) and their shared pathogenesis remains unclear.
• Existing metrics do not differentiate the underlying causes of acute decreases in kidney excretory function.

Purpose of the Study:

• To investigate the distinct pathogenetic mechanisms of iAKI and vAKI.
• To determine if iAKI and vAKI share common molecular pathways or should be considered separate entities.
• To identify potential molecular biomarkers for differentiating iAKI from vAKI.

Main Methods:

• Creation of mouse models for iAKI and vAKI with comparable increases in serum creatinine.
• Laser microdissection of specific kidney regions followed by RNA sequencing.
• Analysis of gene expression patterns in kidney tissues and human urine samples.

Main Results:

• Thousands of genes exhibited specific responses to either iAKI or vAKI, with minimal overlap.
• Activated gene sets involved different, functionally unrelated signaling pathways and were localized to distinct kidney regions.
• Distinct gene expression profiles in human urine were identified as potential biomarkers for iAKI or vAKI, but not both.

Conclusions:

• Intrinsic kidney injury (iAKI) and volume-depleted AKI (vAKI) are biologically distinct conditions.
• Molecular analyses reveal significant differences in gene expression and signaling pathways between iAKI and vAKI.
• Current diagnostic definitions of acute kidney injury require clarification based on molecular distinctions between iAKI and vAKI.