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Endothelial-myofibroblast transition contributes to the early development of diabetic renal interstitial fibrosis in streptozotocin-induced diabetic mice.

ABSTRACT: Diabetic nephropathy is the leading cause of chronic renal failure. Myofibroblasts play a major role in the synthesis and secretion of extracellular matrix in diabetic renal fibrosis. Increasing evidence suggests that endothelial cells may undergo endothelial-myofibroblast transition under physiological and pathophysiological circumstances. Therefore, this study investigates whether endothelial-myofibroblast transition occurs and contributes to the development of diabetic renal interstitial fibrosis. Diabetes was induced by administration of streptozotocin to Tie2-Cre;LoxP-EGFP mice, an endothelial lineage-traceable mouse line generated by crossbreeding B6.Cg-Tg(Tek-cre)12F1v/J mice with B6.Cg-Tg(ACTB-Bgeo/GFP)21Lbe/J mice. The endothelial-myofibroblast transition was also studied in MMECs (a mouse pancreatic microvascular endothelial cell line) and primary cultures of CD31+/EYFP- (enhanced yellow fluorescent protein) endothelial cells isolated from adult normal alpha-smooth muscle actin promoter-driven-EYFP (alpha-SMA/EYFP) mouse kidneys. Confocal microscopy demonstrated that 10.4 +/- 4.2 and 23.5 +/- 7.4% of renal interstitial myofibroblasts (alpha-SMA+) in 1- and 6-month streptozotocin-induced diabetic kidneys were of endothelial origin (EGFP+/alpha-SMA+ cells), compared with just 0.2 +/- 0.1% of myofibroblasts in vehicle-treated Tie2-Cre;LoxP-EGFP mice (P < 0.01). Confocal microscopy and real-time PCR showed that transforming growth factor (TGF)-beta1 induced de novo expression of alpha-SMA and loss of expression of VE-cadherin and CD31 in MMECs and primary cultures of renal endothelial cells in a time- and dose-dependent fashion. These findings demonstrate that the endothelial-myofibroblast transition occurs and contributes to the early development and progression of diabetic renal interstitial fibrosis and suggest that the endothelial-myofibroblast transition may be a therapeutic target.

SUBMITTER: Li J

PROVIDER: S-EPMC2751535 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Endothelial-myofibroblast transition contributes to the early development of diabetic renal interstitial fibrosis in streptozotocin-induced diabetic mice.

Li Jinhua J Qu Xinli X Bertram John F JF

The American journal of pathology 20090903 4

Diabetic nephropathy is the leading cause of chronic renal failure. Myofibroblasts play a major role in the synthesis and secretion of extracellular matrix in diabetic renal fibrosis. Increasing evidence suggests that endothelial cells may undergo endothelial-myofibroblast transition under physiological and pathophysiological circumstances. Therefore, this study investigates whether endothelial-myofibroblast transition occurs and contributes to the development of diabetic renal interstitial fibr ...[more]

PMID: 19729486

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Project description:Renal interstitial fibrosis is considered to be the typical manifestation of diabetic nephropathy (DN). Mangiferin has shown positive effect on the prevention or treatment of diabetes and its complications. The aim of this study was to explore the inhibitive effect and mechanism of mangiferin on renal interstitial fibrosis in diabetic mice. Streptozotocin- (STZ-) induced diabetic mice were treated with mangiferin (15, 30, and 60?mg/kg/d) for 4 weeks. The morphology of kidneys was observed by Masson's trichrome staining, and the biochemical parameters (fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), blood urea nitrogen (BUN), serum creatinine (SCr), and urine protein) were determined by kits. In addition, the levels of inflammatory cytokines (tumor necrosis factor-? (TNF-?), interleukin- (IL-) 6, and IL-1?), antioxidant enzymes (SOD, CAT, and GSH-Px), MDA, and ROS were assessed. Furthermore, the expressions of fibronectin (FN), collagen I (Col I), and ?-SMA were measured by immunohistochemistry. Regulations of TGF-?1 and the PTEN/PI3K/Akt pathway were detected by Western blotting. Treatment with mangiferin significantly ameliorated renal dysfunction in diabetic mice, as evidenced by the increase in body weight and decreases in FBG, TG, TC, BUN, SCr, urine protein, and the kidney to body weight ratio (KW/BW). Furthermore, mangiferin treatment prevented renal interstitial fibrosis evidenced by decreases in the positive expression of FN, Col I, and ?-SMA, in comparison with morphological changes in the renal tissue. Meanwhile, mangiferin increased antioxidant enzymes, reduced the TNF-?, IL-6, and IL-1?, as well as MDA and ROS. Additionally, mangiferin administration also downregulated TGF-?1, upregulated PTEN, and decreased the phosphorylation of both PI3K and Akt. These findings demonstrate that mangiferin may reduce inflammation and oxidative stress in DN, thereby inhibiting the renal interstitial fibrosis by reducing the TGF-?1-mediated elevation of Col I, FN, and ?-SMA through the PTEN/PI3K/Akt pathway.

Project description:BackgroundMacular fibrosis causes irreparable vision loss in neovascular age-related macular degeneration (nAMD) even with anti-vascular endothelial growth factor (VEGF) therapy. Inflammation is known to play an important role in macular fibrosis although the underlying mechanism remains poorly defined. The aim of this study was to understand how infiltrating macrophages and complement proteins may contribute to macular fibrosis.MethodsSubretinal fibrosis was induced in C57BL/6J mice using the two-stage laser protocol developed by our group. The eyes were collected at 10, 20, 30 and 40 days after the second laser and processed for immunohistochemistry for infiltrating macrophages (F4/80 and Iba-1), complement components (C3a and C3aR) and fibrovascular lesions (collagen-1, Isolectin B4 and α-SMA). Human retinal sections with macular fibrosis were also used in the study. Bone marrow-derived macrophages (BMDMs) from C57BL/6J mice were treated with recombinant C3a, C5a or TGF-β for 48 and 96 h. qPCR, Western blot and immunohistochemistry were used to examine the expression of myofibroblast markers. The involvement of C3a-C3aR pathway in macrophage to myofibroblast transition (MMT) and subretinal fibrosis was further investigated using a C3aR antagonist (C3aRA) and a C3a blocking antibody in vitro and in vivo.ResultsApproximately 20~30% of F4/80+ (or Iba-1+) infiltrating macrophages co-expressed α-SMA in subretinal fibrotic lesions both in human nAMD eyes and in the mouse model. TGF-β and C3a, but not C5a treatment, significantly upregulated expression of α-SMA, fibronectin and collagen-1 in BMDMs. C3a-induced upregulation of α-SMA, fibronectin and collagen-1 in BMDMs was prevented by C3aRA treatment. In the two-stage laser model of induced subretinal fibrosis, treatment with C3a blocking antibody but not C3aRA significantly reduced vascular leakage and Isolectin B4+ lesions. The treatment did not significantly alter collagen-1+ fibrotic lesions.ConclusionsMMT plays a role in macular fibrosis secondary to nAMD. MMT can be induced by TGF-β and C3a but not C5a. Further research is required to fully understand the role of MMT in macular fibrosis. Macrophage to myofibroblast transition (MMT) contributes to subretinal fibrosis. Subretinal fibrosis lesions contain various cell types, including macrophages and myofibroblasts, and are fibrovascular. Myofibroblasts are key cells driving pathogenic fibrosis, and they do so by producing excessive amount of extracellular matrix proteins. We have found that infiltrating macrophages can transdifferentiate into myofibroblasts, a phenomenon termed macrophage to myofibroblast transition (MMT) in macular fibrosis. In addition to TGF-β1, C3a generated during complement activation in CNV can also induce MMT contributing to macular fibrosis. RPE = retinal pigment epithelium. BM = Bruch's membrane. MMT = macrophage to myofibroblast transition. TGFB = transforming growth factor β. a-SMA = alpha smooth muscle actin. C3a = complement C3a.

Dataset Information

Endothelial-myofibroblast transition contributes to the early development of diabetic renal interstitial fibrosis in streptozotocin-induced diabetic mice.

Publications

Endothelial-myofibroblast transition contributes to the early development of diabetic renal interstitial fibrosis in streptozotocin-induced diabetic mice.

Similar Datasets

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