(1317) Renal Tubule TIMP2 Promotes Kidney Fibrosis by Facilitating Mitochondrial Dysfunction and Glycolysis

Introduction: Acute kidney injury (AKI) is associated with high morbidity and mortality rate and tends to progress to chronic kidney disease (CKD) and ultimately end-stage renal disease (ESRD). CKD is a huge health burden and is projected to become the fifth leading cause of death globally. The central characteristic of CKD is renal interstitial fibrosis (RIF). Recent studies have shown that due to mitochondrial dysfunction during AKI, renal tubular epithelial cells are prompted to undergo metabolic reprogramming, with a shutdown of fatty acid β-oxidation and an increase in glycolysis, which may lead to inflammation, lipid accumulation, and fibrosis. Metalloproteinase inhibitor 2 (TIMP2) is a secreted protein considered an AKI biomarker. We hypothesized that TIMP2 could promote glycolysis by exacerbating mitochondrial damage, leading to RIF.

Methods: Pathological sections of various types of CKD in humans were collected. TIMP2 renal tubular epithelial cell-specific knockout mice were utilized for ischemia-reperfusion injury and aristolochic acid-induced RIF model. RNA-seq, L-lactate concentration assay, glycolytic stress test, and mitochondrial stress test, JC-1, MitoTracker, MitoSOX, transmission electron microscopy, and cell co-culture were employed to explore mechanisms.

Results:

Results: Elevated TIMP2 expression was found in human IgA nephropathy, diabetic nephropathy, lupus nephropathy, and hypertensive nephropathy. TIMP2 was significantly induced in the fibrotic renal cortex in I/R and AA mices. Cre+/TIMP2fl/fl mice had attenuated mitochondrial dysfunction, renal tubular injury, and improved renal fibrosis. RNA-seq revealed that the expression of glycolysis-related genes distinctly declined in Cre+/TIMP2fl/fl mice. In vitro experiments, TIMP2 overexpression enhanced glycolysis, led to elevated expression of fibrosis markers in rat renal fibroblasts and increased macrophage influx. Mitochondrial complex inhibitors can somewhat restore glycolysis attenuated by TIMP2 knockdown.TIMP2 could regulate significantly mitochondrial homeostasis, renal interstitial fibroblasts proliferation, and RIF via hedgehog signaling pathway.

Conclusions: In summary, our study demonstrated for the first time the critical role of TIMP2 in promoting renal fibrosis by aggravating mitochondrial damage and enhancing glycolysis.