Short-term peaks in glucose promote renal fibrogenesis independently of total glucose exposure

2004 ◽  
Vol 287 (2) ◽  
pp. F268-F273 ◽  
Author(s):  
T. S. Polhill ◽  
S. Saad ◽  
P. Poronnik ◽  
G. R. Fulcher ◽  
C. A. Pollock
Keyword(s):  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Vascular Complications ◽  
Collagen Matrix ◽  
Transforming Growth Factor Β ◽  
Short Term ◽  
Proline Incorporation ◽  
Elevated Glucose ◽  
Total Glucose ◽  
Renal Fibrogenesis

Postprandial hyperglycemia is implicated as a risk factor predisposing to vascular complications. This study was designed to assess recurrent short-term increases in glucose on markers of renal fibrogenesis. Human renal cortical fibroblasts were exposed to fluctuating short-term (2 h) increases to 15 mM d-glucose, three times a day over 72 h, on a background of 5 mM d-glucose. To determine whether observed changes were due to fluctuating osmolality, identical experiments were undertaken with cells exposed to l-glucose. Parallel experiments were performed in cells exposed to 5 mM d-glucose and constant exposure to either 15 or 7.5 mM d-glucose. Fluctuating d-glucose increased extracellular matrix, as measured by proline incorporation ( P < 0.05), collagen IV ( P < 0.005), and fibronectin production ( P < 0.001), in association with increased tissue inhibitor of matrix metalloproteinase (MMP) ( P < 0.05). Sustained exposure to 15 mM d-glucose increased fibronectin ( P < 0.001), in association with increased MMP-2 ( P = 0.01) and MMP-9 activity ( P < 0.05), suggestive of a protective effect on collagen matrix accumulation. Transforming growth factor-β1 (TGF-β1) mRNA was increased after short-term (90 min) exposure to 15 mM glucose ( P < 0.05) and after 24-h exposure to 7.5 mM ? ( P < 0.05). Normalization of TGF-β1 secretion occurred within 48 h of constant exposure to an elevated glucose. Fluctuating l-glucose also induced TGF-β1 mRNA and a profibrotic profile, however, to a lesser extent than observed with exposure to fluctuating d-glucose. The results suggest that exposure to fluctuating glucose concentrations increases renal interstitial fibrosis compared with stable elevations in d-glucose. The effects are, in part, due to the inherent osmotic changes.

scholarly journals Noncanonical TGF-β pathways, mTORC1 and Abl, in renal interstitial fibrogenesis

2010 ◽  
Vol 298 (1) ◽  
pp. F142-F149 ◽  
Author(s):  
Shinong Wang ◽  
Mark C. Wilkes ◽  
Edward B. Leof ◽  
Raimund Hirschberg
Keyword(s):  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Transforming Growth Factor Β ◽  
Renal Diseases ◽  
Obstructive Nephropathy ◽  
Renal Fibrogenesis

Renal interstitial fibrosis is a major determinant of renal failure in the majority of chronic renal diseases. Transforming growth factor-β (TGF-β) is the single most important cytokine promoting renal fibrogenesis. Recent in vitro studies identified novel non-smad TGF-β targets including p21-activated kinase-2 (PAK2), the abelson nonreceptor tyrosine kinase (c-Abl), and the mammalian target of rapamycin (mTOR) that are activated by TGF-β in mesenchymal cells, specifically in fibroblasts but less in epithelial cells. In the present studies, we show that non-smad effectors of TGF-β including PAK2, c-Abl, Akt, tuberin (TSC2), and mTOR are activated in experimental unilateral obstructive nephropathy in rats. Treatment with c-Abl or mTOR inhibitors, imatinib mesylate and rapamycin, respectively, each blocks noncanonical (non-smad) TGF-β pathways in the kidney in vivo and diminishes the number of interstitial fibroblasts and myofibroblasts as well as the interstitial accumulation of extracellular matrix proteins. These findings indicate that noncanonical TGF-β pathways are activated during the early and rapid renal fibrogenesis of obstructive nephropathy. Moreover, the current findings suggest that combined inhibition of key regulators of these non-smad TGF-β pathways even in dose-sparing protocols are effective treatments in renal fibrogenesis.

Metalloproteinase and growth factor interactions: do they play a role in pulmonary fibrosis?

2002 ◽  
Vol 283 (1) ◽  
pp. L1-L11 ◽  
Author(s):  
Margaret K. Winkler ◽  
John L. Fowlkes
Keyword(s):  
Acute Lung Injury ◽  
Growth Factors ◽  
Growth Factor ◽  
Pulmonary Fibrosis ◽  
Lung Injury ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Inflammatory Cells ◽  
Transforming Growth Factor Β ◽  
Target Cells

Chronic lung disease due to interstitial fibrosis can be a consequence of acute lung injury and inflammation. The inflammatory response is mediated through the migration of inflammatory cells, actions of proinflammatory cytokines, and the secretion of matrix-degrading proteinases. After the initial inflammatory insult, successful healing of the lung may occur, or alternatively, dysregulated tissue repair can result in scarring and fibrosis. On the basis of recent insights into the mechanisms underlying acute lung injury and its long-term consequences, data suggest that proteinases, such as the matrix metalloproteinases (MMPs), may not only be involved in the breakdown and remodeling that occurs during the injury but may also cause the release of growth factors and cytokines known to influence growth and differentiation of target cells within the lung. Through the release of and activation of fibrosis-promoting cytokines and growth factors such as transforming growth factor-β1, tumor necrosis factor-α, and insulin-like growth factors by MMPs, we propose that these metalloproteinases may be integral to the initiation and progression of pulmonary fibrosis.

scholarly journals Changes in cardiac resident fibroblast physiology and phenotype in aging

2018 ◽  
Vol 315 (4) ◽  
pp. H745-H755 ◽  
Author(s):  
JoAnn Trial ◽  
Katarzyna A. Cieslik
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Cardiac Fibroblasts ◽  
Transforming Growth Factor Β ◽  
Tissue Homeostasis ◽  
Apparent Paradox ◽  
Smad Pathway ◽  
Activated Fibroblasts ◽  
Resident Fibroblast

The cardiac fibroblast plays a central role in tissue homeostasis and in repair after injury. With aging, dysregulated cardiac fibroblasts have a reduced capacity to activate a canonical transforming growth factor-β-Smad pathway and differentiate poorly into contractile myofibroblasts. That results in the formation of an insufficient scar after myocardial infarction. In contrast, in the uninjured aged heart, fibroblasts are activated and acquire a profibrotic phenotype that leads to interstitial fibrosis, ventricular stiffness, and diastolic dysfunction, all conditions that may lead to heart failure. There is an apparent paradox in aging, wherein reparative fibrosis is impaired but interstitial, adverse fibrosis is augmented. This could be explained by analyzing the effectiveness of signaling pathways in resident fibroblasts from young versus aged hearts. Whereas defective signaling by transforming growth factor-β leads to insufficient scar formation by myofibroblasts, enhanced activation of the ERK1/2 pathway may be responsible for interstitial fibrosis mediated by activated fibroblasts. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/fibroblast-phenotypic-changes-in-the-aging-heart/ .

scholarly journals Glycolysis inhibitors suppress renal interstitial fibrosis via divergent effects on fibroblasts and tubular cells

2019 ◽  
Vol 316 (6) ◽  
pp. F1162-F1172 ◽  
Author(s):  
Qingqing Wei ◽  
Jennifer Su ◽  
Guie Dong ◽  
Ming Zhang ◽  
Yuqing Huo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Collagen Type ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Transforming Growth Factor Β ◽  
Type I ◽  
Pathological Feature ◽  
Renal Interstitial Fibrosis ◽  
Tubular Cells ◽  
Glycolysis Inhibitors

Renal interstitial fibrosis is a common pathological feature of chronic kidney disease that may involve changes of metabolism in kidney cells. In the present study, we first showed that blockade of glycolysis with either dichloroacetate (DCA) or shikonin to target different glycolytic enzymes reduced renal fibrosis in a mouse model of unilateral ureteral obstruction (UUO). Both inhibitors evidently suppressed the induction of fibronectin and collagen type I in obstructed kidneys, with DCA also showing inhibitory effects on collagen type IV and α-smooth muscle actin (α-SMA). Histological examination also confirmed less collagen deposition in DCA-treated kidneys. Both DCA and shikonin significantly inhibited renal tubular apoptosis but not interstitial apoptosis in UUO. Macrophage infiltration after UUO injury was also suppressed. Shikonin, but not DCA, caused obvious animal weight loss during UUO. To determine whether shikonin and DCA worked on tubular cells and/or fibroblasts, we tested their effects on cultured renal proximal tubular BUMPT cells and renal NRK-49F fibroblasts during hypoxia or transforming growth factor-β1 treatment. Although both inhibitors reduced fibronectin and α-SMA production in NRK-49F cells during hypoxia or transforming growth factor-β1 treatment, they did not suppress fibronectin and α-SMA expression in BUMPT cells. Altogether, these results demonstrate the inhibitory effect of glycolysis inhibitors on renal interstitial fibrosis. In this regard, DCA is more potent for fibrosis inhibition and less toxic to animals than shikonin.

scholarly journals Uncoupling of ER-mitochondrial calcium communication by transforming growth factor-β

2008 ◽  
Vol 295 (5) ◽  
pp. F1303-F1312 ◽  
Author(s):  
Pál Pacher ◽  
Kumar Sharma ◽  
György Csordás ◽  
Yanqing Zhu ◽  
György Hajnóczky
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Vascular Complications ◽  
Transforming Growth Factor Β ◽  
Sole Source ◽  
Atp Production ◽  
Permeabilized Cells ◽  
Cellular Processes ◽  
Diabetic Vascular Complications ◽  
Key Factor

Transforming growth factor-β (TGF-β) has been implicated as a key factor in mediating many cellular processes germane to disease pathogenesis, including diabetic vascular complications. TGF-β alters cytosolic [Ca2+] ([Ca2+]c) signals, which in some cases may result from the downregulation of the IP3 receptor Ca2+ channels (IP3R). Ca2+ released by IP3Rs is effectively transferred from endoplasmic reticulum (ER) to the mitochondria to stimulate ATP production and to allow feedback control of the Ca2+ mobilization. To assess the effect of TGF-β on the ER-mitochondrial Ca2+ transfer, we first studied the [Ca2+]c and mitochondrial matrix Ca2+ ([Ca2+]m) signals in single preglomerular afferent arteriolar smooth muscle cells (PGASMC). TGF-β pretreatment (24 h) decreased both the [Ca2+]c and [Ca2+]m responses evoked by angiotensin II or endothelin. Strikingly, the [Ca2+]m signal was more depressed than the [Ca2+]c signal and was delayed. In permeabilized cells, TGF-β pretreatment attenuated the rate but not the magnitude of the IP3-induced [Ca2+]c rise, yet caused massive depression of the [Ca2+]m responses. ER Ca2+ storage and mitochondrial uptake of added Ca2+ were not affected by TGF-β. Also, TGF-β had no effect on mitochondrial distribution and on the ER-mitochondrial contacts assessed by two-photon NAD(P)H imaging and electron microscopy. Downregulation of both IP3R1 and IP3R3 was found in TGF-β-treated PGASMC. Thus, TGF-β causes uncoupling of mitochondria from the ER Ca2+ release. The sole source of this would be suppression of the IP3R-mediated Ca2+ efflux, indicating that the ER-mitochondrial Ca2+ transfer depends on the maximal rate of Ca2+ release. The impaired ER-mitochondrial coupling may contribute to the vascular pathophysiology associated with TGF-β production.

scholarly journals High doses of TGF-β potently suppress type I collagen via the transcription factor CUX1

2011 ◽  
Vol 22 (11) ◽  
pp. 1836-1844 ◽  
Author(s):  
Maria Fragiadaki ◽  
Tetsurou Ikeda ◽  
Abigail Witherden ◽  
Roger M Mason ◽  
David Abraham ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Transforming Growth Factor Β ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Type I ◽  
Aberrant Expression

Transforming growth factor-β (TGF-β) is an inducer of type I collagen, and uncontrolled collagen production leads to tissue scarring and organ failure. Here we hypothesize that uncovering a molecular mechanism that enables us to switch off type I collagen may prove beneficial in treating fibrosis. For the first time, to our knowledge, we provide evidence that CUX1 acts as a negative regulator of TGF-β and potent inhibitor of type I collagen transcription. We show that CUX1, a CCAAT displacement protein, is associated with reduced expression of type I collagen both in vivo and in vitro. We show that enhancing the expression of CUX1 results in effective suppression of type I collagen. We demonstrate that the mechanism by which CUX1 suppresses type I collagen is through interfering with gene transcription. In addition, using an in vivo murine model of aristolochic acid (AA)-induced interstitial fibrosis and human AA nephropathy, we observe that CUX1 expression was significantly reduced in fibrotic tissue when compared to control samples. Moreover, silencing of CUX1 in fibroblasts from kidneys of patients with renal fibrosis resulted in increased type I collagen expression. Furthermore, the abnormal CUX1 expression was restored by addition of TGF-β via the p38 mitogen-activated protein kinase pathway. Collectively, our study demonstrates that modifications of CUX1 expression lead to aberrant expression of type I collagen, which may provide a molecular basis for fibrogenesis.

Chronic interstitial fibrosis in the rat kidney induced by long-term (6-mo) exposure to lithium

2013 ◽  
Vol 304 (3) ◽  
pp. F300-F307 ◽  
Author(s):  
Robert J. Walker ◽  
John P. Leader ◽  
Jennifer J. Bedford ◽  
Glenda Gobe ◽  
Gerard Davis ◽  
...  
Keyword(s):  
Cellular Response ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Rat Kidney ◽  
Human Kidney ◽  
Transforming Growth Factor Β ◽  
Underlying Mechanisms ◽  
Immunohistochemical Studies ◽  
Active Inflammation

There is a lack of suitable animal models that replicate the slowly progressive chronic interstitial fibrosis that is characteristic of many human chronic nephropathies. We describe a chronic long-term (6-mo) model of lithium-induced renal fibrosis, with minimal active inflammation, which mimics chronic kidney interstitial fibrosis seen in the human kidney. Rats received lithium via their chow (60 mmol lithium/kg food) daily for 6 mo. No animals died during the exposure. Nephrogenic diabetes insipidus was established by 3 wk and persisted for the 6 mo. Following metabolic studies, the animals were killed at 1, 3, and 6 mo and the kidneys were processed for histological and immunohistochemical studies. Progressive interstitial fibrosis, characterized by increasing numbers of myofibroblasts, enhanced transforming growth factor-β1 expression and interstitial collagen deposition, and a minimal inflammatory cellular response was evident. Elucidation of the underlying mechanisms of injury in this model will provide a greater understanding of chronic interstitial fibrosis and allow the development of intervention strategies to prevent injury.

LIM homeobox transcription factor 1B expression affects renal interstitial fibrosis and apoptosis in unilateral ureteral obstructed rats

2014 ◽  
Vol 306 (12) ◽  
pp. F1477-F1488 ◽  
Author(s):  
Tian-Biao Zhou ◽  
Chao Ou ◽  
Yuan-Han Qin ◽  
Feng-Ying Lei ◽  
Wei-Fang Huang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Caspase 3 ◽  
Collagen Type ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Transforming Growth Factor Β ◽  
Negative Regulator ◽  
Collagen Type Iii ◽  
Renal Interstitial Fibrosis ◽  
Homeobox Transcription Factor

LIM homeobox transcription factor 1B (LMX1B) is a transcription factor of the LIM homeodomain type and has been implicated in the development of diverse structures such as limbs, kidneys, eyes, and the brain. Furthermore, LMX1B has been implicated in nail-patella syndrome, which is predominantly characterized by malformation of limbs and nails, and in 30% of patients, nephropathy, including renal fibrosis, is observed. Since no reports were available that studied the link between LMX1B expression and renal interstitial fibrosis, we explored if LMX1B affects typical markers of fibrosis, e.g., extracellular matrix components, profibrotic factors, and apoptosis as the final detrimental consequence. We recently showed that LMX1B acts as a negative regulator of transforming growth factor-βl, collagen type III, fibronectin, cleaved caspase-3, and the cell apoptosis rate in a renal tubular epithelial cell system under hypoxic conditions. Here, we confirmed these results in unilateral ureteral obstructed rats. Furthermore, LMX1B was distinctly expressed throughout the glomerulus and tubule lining, including epithelial cells. Knockdown of LMX1B aggravated the expression of fibrosis markers, oxidative stress, and apoptosis compared with the already increased levels due to unilateral ureteral obstruction, whereas overexpression attenuated these effects. In conclusion, reduced LMX1B levels clearly represent a risk factor for renal fibrosis, whereas overexpression affords some level of protection. In general, LMX1B may be considered to be a negative regulator of the fibrosis index, transforming growth factor-βl, collagen type III, fibronectin, cleaved caspase-3, cell apoptosis, ROS, and malondialdehyde ( r = −0.756, −0.698, −0.921, −0.923, −0.843, −0.794, −0.883, and −0.825, all P < 0.01).

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