Project description:Tissue inhibitors of metalloproteinases (TIMP) are endogenous inhibitors of matrix metalloproteinases (MMP). While TIMP2 and TIMP3 inhibit MMPs, TIMP3 also inhibits activation of pro-MMP2 whereas TIMP2 promotes it. Here we assessed the differential role of TIMP2 and TIMP3 in renal injury using the unilateral ureteral obstruction model. Gene microarray assay showed that post-obstruction, the lack of TIMP3 had a greater impact on gene expression of intermediate, late injury- and repair-induced transcripts, kidney selective transcripts and solute carriers. Renal injury in TIMP3-/-, but not in TIMP2-/- mice increased expression of collagen type I/III, connective tissue growth factor, transforming growth factor-β and the downstream Smad2/3 pathway. Interestingly, ureteral obstruction markedly increased MMP2 activation in the kidneys of TIMP3-/- mice which was completely blocked in the kidneys of TIMP2-/- mice. These changes are consistent with enhanced renal tubulointerstitial fibrosis in TIMP3-/- and its reduction in TIMP2-/- mice. The activity of tumor necrosis factor-α converting enzyme, caspase-3 and mitogen activated kinases were elevated in the kidneys of TIMP3-/- but not TIMP2-/- mice, suggesting enhanced activation of apoptotic and pathological signaling pathways only in the obstructed kidney of TIMP3-/- mice. Thus, TIMP2 and TIMP3 play differential and contrasting roles in renal injury, TIMP3 protects from damage whereas TIMP2 promotes injury through MMP2 activation. Kidneys from the wild type (WT), TIMP2-/- and TIMP3-/- mice undergoing sham or unilateral ureteral obstruction (UUO) procedures
Project description:Tissue inhibitors of metalloproteinases (TIMP) are endogenous inhibitors of matrix metalloproteinases (MMP). While TIMP2 and TIMP3 inhibit MMPs, TIMP3 also inhibits activation of pro-MMP2 whereas TIMP2 promotes it. Here we assessed the differential role of TIMP2 and TIMP3 in renal injury using the unilateral ureteral obstruction model. Gene microarray assay showed that post-obstruction, the lack of TIMP3 had a greater impact on gene expression of intermediate, late injury- and repair-induced transcripts, kidney selective transcripts and solute carriers. Renal injury in TIMP3-/-, but not in TIMP2-/- mice increased expression of collagen type I/III, connective tissue growth factor, transforming growth factor-β and the downstream Smad2/3 pathway. Interestingly, ureteral obstruction markedly increased MMP2 activation in the kidneys of TIMP3-/- mice which was completely blocked in the kidneys of TIMP2-/- mice. These changes are consistent with enhanced renal tubulointerstitial fibrosis in TIMP3-/- and its reduction in TIMP2-/- mice. The activity of tumor necrosis factor-α converting enzyme, caspase-3 and mitogen activated kinases were elevated in the kidneys of TIMP3-/- but not TIMP2-/- mice, suggesting enhanced activation of apoptotic and pathological signaling pathways only in the obstructed kidney of TIMP3-/- mice. Thus, TIMP2 and TIMP3 play differential and contrasting roles in renal injury, TIMP3 protects from damage whereas TIMP2 promotes injury through MMP2 activation.
Project description:Tubulointerstitial injury plays an important role in diabetic nephropathy (DN) progression; however, no reliable urinary molecule has been used to predict tubulointerstitial injury and renal outcome of DN clinically. In this study, based on tubulointerstitial transcriptome, we identified secretory leukocyte peptidase inhibitor (SLPI) as the molecule associated with renal fibrosis and prognosis of DN. In tubular cells, high glucose could upregulate SLPI, which bound with β-catenin and GSK-3β reciprocally, abolished the interaction between β-catenin and GSK-3β, diminished GSK-3β-regulated β-catenin phosphorylation and the subsequent ubiquitination and degradation, thus led to β-catenin signaling activation and renal fibrosis. Db/db mice injected with adenovirus carrying Slpi-3xflag-GFP (Ad-Slpi-GFP) developed β-catenin signaling activation in the proximal tubule, worse albuminuria and tubulointerstitial fibrosis. Conversely, Slpi knockout (KO) mice with STZ-induced DN developed less albuminuria, tubulointerstitial fibrosis and β-catenin signaling activation. Furthermore, clinical studies showed that urinary SLPI protein level (uSLPI/Cr) had significant correlation with intrarenal SLPI mRNA and interstitial fibrosis. In an independent prospective cohort enrolled 711 patients with biopsy proven DN, uSLPI/Cr level was significantly associated with eGFR slope and improved the prediction value of renal outcome. Together, our study identified SLPI as a novel critical regulator for the progression of tubulointerstitial injury, which may be used as an independent risk predictor of DN progression.
Project description:We created a rat renal congestion model and investigated the effect of renal congestion on hemodynamics and molecular mechanisms. The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion in the left kidney only. Left kidney congestion reduced renal blood flow, glomerular filtration rate, and increased renal interstitial hydrostatic pressure. Tubulointerstitial and glomerular injury and medullary thick ascending limb hypoxia were observed only in the congestive kidneys. Molecules related to extracellular matrix expansion, tubular injury, and focal adhesion were upregulated in microarray analysis. Renal decapsulation ameliorated the tubulointerstitial injury. Electron microscopy captured pericyte detachment in the congestive kidneys. Transgelin and platelet-derived growth factor receptors, as indicators of pericyte-myofibroblast transition, were upregulated in the pericytes and the adjacent interstitium. With the compression of the peritubular capillaries and tubules, hypoxia and physical stress induce pericyte detachment, which could result in extracellular matrix expansion and tubular injury in renal congestion.