Reduction of Perlecan Synthesis and Induction of TGF-β1 in Human Peritoneal Mesothelial Cells Due to High Dialysate Glucose Concentration

Abstract

Abstract. Prolonged exposure of the peritoneal mesothelium to high dialysate glucose concentrations reduces anionic sites that are critical to its selective permeability, thereby impairing the peritoneal transport properties in patients on long-term peritoneal dialysis (PD). Perlecan, an anionic heparan sulfate proteoglycan, is pivotal to the selective permeability of basement membranes, and high glucose concentrations modulate its synthesis in mesangial cells. The effect of glucose on perlecan expression in the peritoneal mesothelium has not been established. We investigated perlecan expression in peritoneal biopsies from patients on PD, and the effect of high glucose concentrations on perlecan synthesis in cultured human peritoneal mesothelial cells (HPMC). Peritoneal biopsies from PD patients showed reduced perlecan expression compared with controls. Exposure of HPMC to high glucose concentrations resulted in a dose-dependent reduction in the synthesis of perlecan polypeptide and its deposition into the extracellular matrix. These effects were mediated in part through the induction of TGF-␤1. Characterization studies showed that perlecan synthesized by HPMC contained solely heparan sulfate glycosaminoglycan (HS GAG) chains, and [35 S]-incorporation studies demonstrated progressive reduction of their de novo synthesis with increasing glucose concentrations (68142 Ϯ 3658, 48147 Ϯ 2517, 31468 Ϯ 5781, and 25575 Ϯ 3621 cpm/g cellular protein for 5 mM, 30 mM, 75 mM, and 120 mM D-glucose, respectively; P Ͻ 0.001 for 5 mM versus 30 mM D-glucose, and P Ͻ 0.0001 for 5 mM versus 75 mM or 120 mM D-glucose). Both the length and the charge density of the HS GAG chains remained unchanged. Reduction of peritoneal perlecan expression in long-term PD was attributed to high dialysate glucose concentrations, which induced TGF-␤1 and reduced perlecan synthesis in HPMC. Since perlecan can sequester growth factors, thereby modulating cell migration and differentiation perturbation of peritoneal perlecan expression contributes to the structural and functional changes of the peritoneum in long-term PD.

Pathophysiological Changes to the Peritoneal Membrane during PD-Related Peritonitis: The Role of Mesothelial Cells

“…In areas where mesothelial cells are still apparent, changes observed are similar to those mentioned above with a loss of microvilli and cell-cell contact [81, 82]. Peritonitis also induces the loss of the underlying basement membrane and promotes extensive interstitial fibrosis attributed to increased synthesis of matrix proteins and a concomitant loss of decorin [3, 38, 77, 83]. Acute infiltration of inflammatory cell into the submesothelium is also noted, which may account at least in part, to the expansion of the interstitial.…”

“…Although the nature of these anionic sites was not further investigated by these researchers, it is possible that perlecan may contribute at least in part to the anionic staining. We have demonstrated that perlecan expression is predominately observed within the mesothelium and underlying basement membrane in peritoneal specimens obtained from new PD patients [38]. Mesothelial expression of perlecan decreased with increasing duration on PD with a concomitant increase in the submesothelium [38].…”

Twist Contributes to Proliferation and Epithelial-to-Mesenchymal Transition–Induced Fibrosis by Regulating YB-1 in Human Peritoneal Mesothelial Cells

“…Lentivirus titers were determined by transfecting human embryonic kidney 293 T cells with a dilution series of the viral suspension, and lentivirus samples with a titer of 4 Â 10 8 transfection units/mL were stored at À80 C. 23,24 Peritoneal Exposure Model in Rats A chronic infusion model of nonuremic animal PD was used, as described previously. 6 …”

“…Some researchers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 have found that the growth and proliferation of HPMCs significantly changes when fibrosis develops in the PM after HG stimulation, followed by the cell cycle progression. 6 Cell proliferation could not be affected or even be inhibited at the initial stimulation time for 48 hours, and then had an abnormal proliferation and cell cycle progress at the following HG stimulation days. Thus, the inhibition of growth and the induction of cell cycle arrest of HPMCs might contribute to protection against PM fibrosis.…”

Treatment of Established Peritoneal Fibrosis by Gene Transfer of Smad7 in a Rat Model of Peritoneal Dialysis

“…Increasing evidence has shown that transforming growth factor (TGF)-␤ is a key mediator of experimental and human peritoneal fibrosis associated with peritoneal dialysis (PD) [5] . In vitro, peritoneal mesothelial cells are the major source of TGF-␤ 1 production in response to high glucose, which leads to extracellular matrix (ECM) accumulation by increasing the synthesis of ECM proteins while reducing their degradation [6,7] . In long-term CAPD patients, the concentrations of TGF-␤ 1 in PD effluents are significantly elevated, particularly in those with peritonitis [8,9] .…”