Matrix metalloproteinase-9 of tubular and macrophage origin contributes to the pathogenesis of renal fibrosis via macrophage recruitment through osteopontin cleavage

Abstract

A pro-fibrotic role of matrix metalloproteinase-9 (MMP-9) in tubular cell epithelial-mesenchymal transition (EMT) is well established in renal fibrosis; however studies from our group and others have demonstrated some previously unrecognized complexity of MMP-9 that has been overlooked in renal fibrosis. Therefore, the aim of this study was to determine the expression pattern, origin and the exact mechanism underlying the contribution of MMP-9 to unilateral ureteral obstruction (UUO), a well-established model of renal fibrosis via MMP-9 inhibition. Renal MMP-9 expression in BALB/c mice with UUO was examined on day 1, 3, 5, 7, 9, 11 and 14. To inhibit MMP-9 activity, MMP-2/9 inhibitor or MMP-9-neutralizing antibody was administered daily for 4 consecutive days from day 0-3, 6-9 or 10-13 and tissues harvested at day 14. In UUO, there was a bi-phasic early-and late-stage upregulation of MMP-9 activity. Interestingly, tubular epithelial cells (TECs) were the predominant source of MMP-9 during early stage, whereas TECs, macrophages and myofibroblasts produced MMP-9 during late-stage UUO. Early-and late-stage inhibition of MMP-9 in UUO mice significantly reduced tubular cell EMT and renal fibrosis. Moreover, MMP-9 inhibition caused a significant reduction in MMP-9-cleaved osteopontin and macrophage infiltration in UUO kidney. Our in vitro study showed MMP-9-cleaved osteopontin enhanced macrophage transwell migration and MMP-9 of both primary TEC and macrophage induced tubular cell EMT. In summary, our result suggests that MMP-9 of both TEC and macrophage origin may directly or indirectly contribute to the pathogenesis of renal fibrosis via osteopontin cleavage, which, in turn further recruit macrophage and induce tubular cell EMT. Our study also highlights the time dependency of its expression and the potential of stage-specific inhibition strategy against renal fibrosis. KEYWORDS: Epithelial-mesenchymal transition; macrophage; matrix metalloproteinase-9; osteopontin; renal fibrosis; tubular epithelial cell Matrix metalloproteinase-9 (MMP-9), also known as gelatinase B, belongs to a large family of zinc-dependent matrixdegrading enzymes called matrix metalloproteinases (MMPs) that have an important role in both physiological and pathological conditions in vivo. 1 MMPs are well known for their anti-fibrotic effect due to their ability to degrade and remodel extracellular matrix (ECM) proteins, however it has been recognized that MMPs can also exert pro-fibrotic effect under various pathological conditions.Myofibroblasts are the effector cells responsible for the production and secretion of ECM in renal fibrosis. It has been reported that myofibroblasts can derive from the activation of renal interstitial fibroblasts, perivascular fibroblasts and pericytes, from bone marrow-derived stem cells and

Macrophage Overexpressing NGAL Ameliorated Kidney Fibrosis in the UUO Mice Model

“…The precise mechanism by which MMP-9 contributes to renal fibrosis still is a matter of debate. Our results agreed with those reported by Tan et al suggesting that MMP-9 contributes to the pathogenesis of renal fibrosis via macrophage recruitment [30]. Furthermore, Harris and Wang [2] suggested that Ml macrophages induce renal fibrosis by MMP-9 secretion.…”

Matrix metalloproteinase 9-dependent Notch signaling contributes to kidney fibrosis through peritubular endothelial–mesenchymal transition

“…We previously reported that MMP-9 of both tubular and macrophage origin was critical to TGF-β1-induced tubular cell EMT [6, 24]. It has been confirmed that MMP-9 is necessary for the disruption of epithelial cell basement membrane, a key step to complete the entire course of EMT [26].…”

“…Techniques for isolating glomerular endothelial cells are established [27, 28], but isolation of peritubular endothelial cells has not been described elsewhere. In this study, we isolated MRPECs by our recently established method [6], and investigated the roles of MRPECs in kidney fibrosis. We showed that co-localization of endothelial marker VE-cadherin with mesenchymal marker α-SMA in the kidneys of UUO mice was mainly found outside glomeruli (Figure 1F) in the tubulointerstitial space.…”

“…Matrix metalloproteinase 9 (MMP-9), also known as gelatinase B, has been proven by us and others to cause kidney fibrosis [6, 7]. We have demonstrated that MMP-9 induced epithelial-mesenchymal transition (EMT) in rat proximal tubular epithelial (NRK52E) cells downstream of TGF-β1 and that MMP-9 of macrophage origin is responsible for TGF-β1-induced EMT in murine tubular epithelial (C1.1) cells [6, 7].…”

“…We have demonstrated that MMP-9 induced epithelial-mesenchymal transition (EMT) in rat proximal tubular epithelial (NRK52E) cells downstream of TGF-β1 and that MMP-9 of macrophage origin is responsible for TGF-β1-induced EMT in murine tubular epithelial (C1.1) cells [6, 7]. Recently, we found that MMP-9 also induced EndoMT in human glomerular endothelial cells (unpublished data), but the underlying mechanisms remains unknown.…”