TY - JOUR
AU - Schwenger,, Vedat
AB - Abstract Background Peritoneal dialysis (PD) is limited by peritoneal fibrosis and ultrafiltration failure. This is in part caused by the high concentration of glucose degradation products (GDPs) present in PD fluids (PDF) as a consequence of heat sterilization. Existing research in long-term PD has mainly dealt with the toxicity induced by GDPs and the development of therapeutic strategies to reduce the cellular burden of GDPs. Currently, there are few data regarding the potential role of detoxification systems of GDP in PD. In this study, the role of glyoxalase 1 (Glo1), the major detoxification pathway for dicarbonyl-derived GD such as methylglyoxal (MG) and glyoxal (Gx), was investigated in vivo using heterozygous knock-down mice for Glo1 (Glo1−/+). Methods Wild-type (WT) and Glo1−/+ mice were repeatedly treated with PDF containing low and high amounts of GDP, particularly with respect to the content of dicarbonyls. After 12 weeks of treatment with PDF, peritoneal damage and function were evaluated. Results Glo1−/+ mice treated with PDF showed increased formation of advanced glycation endproduct (AGE) when compared with WT mice, particularly the Gx-derived AGE, carboxymethyl-lysine. This was associated with increased inflammation, neovascularization, increased peritoneal fibrosis and impaired peritoneal function. Conclusions This study suggests a pivotal and underestimated role for Glo1 as a detoxifying enzyme in GDP-associated peritoneal toxicity in PD. The indirect and direct modulation of Glo1 may therefore offer a new therapeutic option in prevention of GDP-induced peritoneal damage in PD. glucose degradation products, glyoxalase, methylglyoxal, mice, peritoneal dialysis INTRODUCTION Peritoneal dialysis (PD) is an accepted treatment option for end-stage renal disease patients. However, long-term PD is limited by structural and functional changes in the peritoneal membrane and eventually a loss of ultrafiltration induced by PD fluids (PDF) [1]. It has been shown that PDF contain not only high glucose concentrations, but also, as a direct consequence of heat-sterilization, high concentrations of glucose degradation products (GDPs). This heterogeneous group of small-molecular-weight carbonyls includes 5-hydroxymethylfuraldehyde and 3,4-dideoxyglucosone-3-ene, as well as the reactive and potent glycating agents, 3-deoxyglucosone (3-DG), glyoxal (Gx) and methylglyoxal (MG) [2–11], collectively referred to as dicarbonyls [12]. GDP exhibits a facile reactivity with various biomolecules, including proteins, DNA and phospholipids, generating stable products at the end of a series of reactions, which have been shown to contribute to the pathogenesis of vascular diseases such as atherosclerosis and diabetes. Recent in vitro studies have demonstrated toxicity of GDP towards human peritoneal mesothelial cells [13, 14], which have been confirmed in vivo [15–18]. Existing basic and clinical research in long-term PD has mainly dealt with GDP-derived toxicity and the development of therapeutic strategies to reduce the cellular burden of GDP [19, 20]. Currently, there are few data regarding the potential role of detoxification systems of GDP in PD. Previously studies have shown that MG is a major biologically active component of GDP in PD [21]. MG reacts with proteins, primarily with arginine residues, to form the advanced glycation endproduct (AGE), MG-derived hydroimidazolone isomer 1 (MG-H1) [22]. The accumulation of MG-H1 and other MG-derived AGE on proteins has been linked to the development and progression of vascular diseases such as atherosclerosis, as well diabetic complications, such as neuropathy [23]. The glyoxalase system, which consists of glyoxalase 1 (Glo1) and glyoxalase 2 (Glo2) and the cofactor, reduced glutathione (GSH), is the major route of detoxification of MG and Gx [24]. In vitro, it has been shown that depletion of GSH and NAPDH by increased production of reactive oxygen species (ROS) can lead to decreased in situ activity of Glo1, and a subsequent increase in MG and MG-derived AGE [25]. In vitro, it has been shown that Glo1 activity is reduced with age and was associated with increased modification of mitochondrial proteins [26, 27], and that in diabetes, reduced Glo1 activity in the sciatic nerve leads to increased susceptibly to modification of sodium-voltaged channel, Nav1.8 and increased neuronal excitability [23]. Furthermore, age-dependent decrease in Glo1 transcription, expression and activity were associated with delayed wound healing [28] and knock-down of Glo1 mimics diabetic nephropathy in non-diabetic mice [29]. Within the context of PD, it has been shown in vitro that treatment of PDF with Glo1, in combination with either GSH or aminoguanidine, a scavenger of dicarbonyls, can substantially reduce the concentration of dicarbonyls in PDF [30, 31]. In this study, the role of Glo1 in modulating dicarbonyl-induced peritoneal damage by PDF was investigated in Glo1 heterozygous-deficient (Glo1−/+) mice. MATERIALS AND METHODS Animals and experimental design Glo1−/+ mice are viable and display normal reproductive function [32]. All strains were backcrossed on the C57BL/6 background >10 times and C57BL/6-mice (Charles River, Boston, MA, USA) served as controls for all transgenic mice. There were no significant differences with respect to age, body weight, blood pressure and haematocrit values between Glo1−/+ and wild-type (WT) mice. Mice were housed individually with a 12-h/12-h light/dark cycle and free access to food and water. All procedures in this study were approved by the Animal Care and Use Committees at the Regierungspräsidium Tübingen and Karlsruhe, Germany. All experiments were performed in 12-week-old female mice (45 WT mice and 45 Glo1−/+ mice). For the evaluation of baseline characteristics, five WT plus five Glo1−/+ mice were anaesthetized and perfusion was performed via the left ventricle. Visceral peritoneal tissue was resected from the root of the mesentery and fresh frozen. For the PD experiment, mice were randomly allocated to four groups each, as shown in Table 1. Twice daily, the animals received an intraperitoneal injection of 1 mL of the respective PDF at 37°C under sterile conditions. The composition of the PDF is given in Table 2. One group of mice remained untreated to obtain baseline histologic and molecular data (C). In a second group, the mice were sham injected without instilling solution as a control for intraperitoneal puncture (IP) trauma. Particular care was taken to avoid artificial injury by thermal trauma (fluids were injected at body temperature) and/or contamination of the injected fluids by bacteria or lipopolysaccharides. After 12 weeks of treatment, the experiment was terminated. Table 1. Experimental groups Group . Treatment . N . WT C Untreated 6 WT IP Sham injection without instilling solution twice daily 8 WT + low GDP Instillation of low GDP-PDF twice daily 13 WT + high GDP Instillation of high GDP-PDF twice daily 11 Glo1−/+ C Untreated 5 Glo1−/+ IP Sham injection without instilling solution twice daily 8 Glo1−/+ + low GDP Instillation of low GDP-PDF twice daily 11 Glo1−/+ + high GDP Instillation of high GDP-PDF twice daily 12 Group . Treatment . N . WT C Untreated 6 WT IP Sham injection without instilling solution twice daily 8 WT + low GDP Instillation of low GDP-PDF twice daily 13 WT + high GDP Instillation of high GDP-PDF twice daily 11 Glo1−/+ C Untreated 5 Glo1−/+ IP Sham injection without instilling solution twice daily 8 Glo1−/+ + low GDP Instillation of low GDP-PDF twice daily 11 Glo1−/+ + high GDP Instillation of high GDP-PDF twice daily 12 WT, wild-type; Glo1−/+, Glyoxalase 1-deficient; C, control; IP, intraperitoneal injection; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. Open in new tab Table 1. Experimental groups Group . Treatment . N . WT C Untreated 6 WT IP Sham injection without instilling solution twice daily 8 WT + low GDP Instillation of low GDP-PDF twice daily 13 WT + high GDP Instillation of high GDP-PDF twice daily 11 Glo1−/+ C Untreated 5 Glo1−/+ IP Sham injection without instilling solution twice daily 8 Glo1−/+ + low GDP Instillation of low GDP-PDF twice daily 11 Glo1−/+ + high GDP Instillation of high GDP-PDF twice daily 12 Group . Treatment . N . WT C Untreated 6 WT IP Sham injection without instilling solution twice daily 8 WT + low GDP Instillation of low GDP-PDF twice daily 13 WT + high GDP Instillation of high GDP-PDF twice daily 11 Glo1−/+ C Untreated 5 Glo1−/+ IP Sham injection without instilling solution twice daily 8 Glo1−/+ + low GDP Instillation of low GDP-PDF twice daily 11 Glo1−/+ + high GDP Instillation of high GDP-PDF twice daily 12 WT, wild-type; Glo1−/+, Glyoxalase 1-deficient; C, control; IP, intraperitoneal injection; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. Open in new tab Table 2. Composition and concentrations of peritoneal dialysis solutions . Low GDP (multi-compartment bag) . High GDP (single-compartment bag) . Sodium (mmol/L) 132 132 Calcium (mmol/L) 1.75 1.75 Magnesium (mmol/L) 0.25 0.25 Chloride (mmol/L) 96.0 96.0 Lactate (mmol/L) 40 40 Glucose (g/L) 25 25 3-Deoxyglucosone (µM) 45.4 399 Gx (µM) 10.2 46.9 MG (µM) 1.94 9.34 . Low GDP (multi-compartment bag) . High GDP (single-compartment bag) . Sodium (mmol/L) 132 132 Calcium (mmol/L) 1.75 1.75 Magnesium (mmol/L) 0.25 0.25 Chloride (mmol/L) 96.0 96.0 Lactate (mmol/L) 40 40 Glucose (g/L) 25 25 3-Deoxyglucosone (µM) 45.4 399 Gx (µM) 10.2 46.9 MG (µM) 1.94 9.34 GDP, glucose degradation products. Open in new tab Table 2. Composition and concentrations of peritoneal dialysis solutions . Low GDP (multi-compartment bag) . High GDP (single-compartment bag) . Sodium (mmol/L) 132 132 Calcium (mmol/L) 1.75 1.75 Magnesium (mmol/L) 0.25 0.25 Chloride (mmol/L) 96.0 96.0 Lactate (mmol/L) 40 40 Glucose (g/L) 25 25 3-Deoxyglucosone (µM) 45.4 399 Gx (µM) 10.2 46.9 MG (µM) 1.94 9.34 . Low GDP (multi-compartment bag) . High GDP (single-compartment bag) . Sodium (mmol/L) 132 132 Calcium (mmol/L) 1.75 1.75 Magnesium (mmol/L) 0.25 0.25 Chloride (mmol/L) 96.0 96.0 Lactate (mmol/L) 40 40 Glucose (g/L) 25 25 3-Deoxyglucosone (µM) 45.4 399 Gx (µM) 10.2 46.9 MG (µM) 1.94 9.34 GDP, glucose degradation products. Open in new tab Preparation of peritoneal tissue Mice were anaesthetized and perfusion was performed via the left ventricle, and visceral peritoneal tissue was resected from the root of the mesentery. For the morphological and immunohistochemical analysis, visceral peritoneal tissue samples were fixed in 6% PFA (pH 7.6), embedded in paraffin and cut into 4 μm thick tissue sections. Histological and immunohistochemical stainings and analysis Tissue sections were deparaffinized, rehydrated and incubated in Tris-buffered saline (TBS). For histology, sections were stained with haematoxylin & eosin, periodic acid Schiff (PAS) reagent. For immunohistochemistry the following antibodies were used: anti-MG-AGE (1:50), anti-carboxymethyl-lysine (CML) (1:50) (BioLogo, Kronshagen, Germany), anti-transforming growth factor-β1 (TGF-β1) (1:100), anti-vascular endothelial growth factor (VEGF) (1:100), anti-vimentin (1:25), anti-receptor for AGE (RAGE) (1:50) (Santa Cruz Biotechnology, Santa Cruz, CA, USA) and anti-interleukin 6 (IL-6) (1:250) (BioTrend, Köln, Germany). The sections were incubated with the primary antibody overnight at 4°C and thereafter stained with the secondary antibody, alkaline-phosphatase-conjugated streptavidin, fast red, and peroxidase-conjugated histofine simple stain, diaminobenzidine. Replacement of the primary antibodies with TBS served as a negative control. Semiquantitative analysis of MG-AGE, CML, RAGE, TGF-β1, VEGF, vimentin and IL-6 was carried out by two blinded observers using a previously described [20, 33] scoring system that comprises a qualitative score of 0–3 (intensity of the staining: 0 = no staining, 1 = low intensity, 2 = medium intensity, 3 = high intensity) and a quantitative score of 0–4 (0 = normal, 1 = 1–25% of tissue affected, 2 = 26–50% affected, 3 = 51–75% affected; 4 = 76–100% affected). The two scores were multiplied, with a maximum possible score of 12; 20 areas per cross-section were analysed. The maximal thickness of the submesothelial compact zone was measured in sections oriented perpendicular to the serosal surface. Vessel number (using PAS staining) per area was counted on a 121-point grid (Leitz, Wetzlar, Germany). Images were taken using a Nikon DS-Qi1Mc quantitative black and white charge-coupled device camera attached to a Nikon Eclipse 80i upright microscope (Nikon, Düsseldorf, Germany). Clinical parameters Haemoglobin, urea, sodium, potassium, glucose and creatinine were measured with autoanalysers (ADVIA 2400 and ADVIA 2120, Siemens, Eschborn, Germany). Peritoneal equilibration test A modified mini-peritoneal equilibration test (PET) was performed as previously described [34]. Briefly 2 mL of PDF were injected. After 1 h, the intra-abdominal PDF was aspirated and creatinine, urea and sodium were measured. The quotient of dialysate and plasma was determined and the transport type was estimated according to [34, 35]. Determination of dicarbonyl content in PDF The concentration of 3-DG, MG and Gx in PDF was determined by derivatization with 1,2-diamino-4,5-dimethoxybenzene, as previously described [36]. Preparation of total protein extract Frozen peritoneal tissue was grounded to a fine powder using liquid nitrogen. The homogenate was resuspended in ice-cold lysis buffer (10 mM HEPES, 10 mM KCl, 1.5 mM MgCl2, 1 mM EDTA, 0.6% NP40, 0.5 mM DTT, 0.2 mM PMSF; pH 7.9) and incubated on ice for 20 min. The tissue homogenates were then vortex and centrifuged (15000 g, 10 min, 4°C), and supernatants were retained for analysis. The protein concentration for cell and tissue homogenates was determined by Bradford assay using BSA as a standard [37]. Assay of Glo1 activity Glo1 activity was determined by using the spectrometric method, which monitors the initial rate of change in absorbance at 240 nm caused by the formation of S-d-lactoylglutathione [38]. For the conversion of the hemithioacetal to S-d-lactoylglutathione, the change in molar extinction coefficient was Δε240 = 2.86/mM/cm. The standard assay mixture contained 2 mM MG and 2 mM GSH in sodium phosphate buffer (50 mM, pH 6.6, 37°C). The reaction mixture was allowed to stand for 10 min before the addition of the cytosolic protein fraction (20 µg) to ensure the equilibrium of hemithioacetal formation. The activity of Glo1 is given in units (U), where 1 U is the amount of Glo1 that catalyses the formation of 1 µmol of S-d-lactoylglutathione per minute under the stated assay conditions. Quantitative real-time PCR Total RNA was isolated from pulverized peritoneal tissue using the GeneElute™ Mammalian Total RNA miniprep kit (Sigma-Aldrich Chemie, Taufkirchen, Germany), according to the manufacturer's instructions. One microgram of RNA was reverse transcribed (High Capacity cDNA Transcription kit, Applied Biosystems, Inc., Foster City, CA, USA) and transcripts quantified using a Roche LightCycler 480 (Roche Diagnostics, Mannheim, Germany) and KAPA SYBER Fast Master Mix (PEQLAB Biotechnologie GmbH, Erlangen, Germany), according the manufacturer's instructions. The following primer pairs were used: Glo1: 5′-GATTTGGTCACATTGGGATTGC-3′ and 5′-TCCTTTCATTTTCCCGTCATCAG-3; RAGE: 5′-CTTGCTCTATGGGGAGCTGTA-3′ and 5′-GGAGGATTTGAGCCACGCT-3′; β-actin (Reference gene): 5′-GGCTGTATTCCCCTCCATCG-3′ and 5′-CCAGTTGGTAACAATGCCATGT-3′. Melting curve profiles were used to confirm amplification of specific transcripts, and the level of expression was calculated from the respective ΔCt value, based on the second derivative maximum method. Serum total protein fluorescence Total protein fluorescence relating to oxidative and glycation fluorescence of serum samples was performed using a spectrofluorometer (LS 50 B, Perkin Elmer, Überlingen, Germany). For measuring fluorescence, intensity excitation wavelength was set at 350 nm and emission wavelength at 430 nm. Samples were diluted accordingly. Statistical analysis All values are expressed as mean ± SEM. Kruskal–Wallis and Mann–Whitney tests were used as appropriate to test statistical significance. Significance level was set at P < 0.05. Statistical analysis was performed by PC-Statistik (version 5.0, Hoffmann, Giessen, Germany) and GraphPad Prism (version 5; La Jolla, CA, USA). RESULTS Baseline characteristics In comparison with WT mice, Glo1−/+ animals revealed a significantly higher peritoneal expression and activity of Glo1. There was no difference regarding RAGE expression between WT and Glo1−/+ animals before treatment with PDF (Supplementary Figure 1). Dicarbonyl content The amount of 3-DG, MG and Gx of the different PDF is shown in Table 2 and Figure 1. FIGURE 1: Open in new tabDownload slide Chromatography of the dicarbonyl content in low and high GDP-PDF. GDP, glucose degradation products. FIGURE 1: Open in new tabDownload slide Chromatography of the dicarbonyl content in low and high GDP-PDF. GDP, glucose degradation products. Peritoneal MG, Gx AGE and RAGE-formation In WT mice treated with PDF, there was only a minor increase within the peritoneal membrane of MG-AGE and CML, a major AGE formed from lysine and Gx when compared with untreated animals (Figure 2). However, a more pronounced increase in MG-AGE was observed in Glo1−/+ mice treated with high GDP-PDF in comparison to low-GDP treatment (peritoneal staining for MG-AGE: Glo1−/+ + low GDP 3.94 ± 0.29 versus Glo1−/+ + high GDP 6.16 ± 0.48; P < 0.001). The accumulation of CML was significantly higher in Glo1−/+ animals treated with high GDP-PDF compared with WT mice treated with high GDP-PDF (peritoneal staining for CML: WT + low GDP 5.92 ± 0.17 versus WT + high GDP 6.87 ± 0.16; P < 0.01 and Glo1−/+ + low GDP 6.61 ± 0.21 versus Glo1−/+ + high GDP 7.86 ± 0.14; P < 0.001). The expression of RAGE (Supplementary Figure 2) was significantly higher in Glo1−/+ animals treated with high GDP-PDF compared with Glo−/+ mice treated with high GDP-PDF (peritoneal staining for RAGE: Glo1−/+ + low GDP 5.39 ± 0.36 versus Glo1−/+ + high GDP 8.27 ± 0.50; P < 0.01). FIGURE 2: Open in new tabDownload slide Increased expression of MG-AGE and CML. Immunohistochemical staining of visceral peritoneum showing a higher expression of MG-AGE (A, CML (B) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. Representative images of MG-AGE staining are given in (A) (right panel). Magnification ×600, scale bar represents 33 μm. MG, methylglyoxal; AGE, advanced glycation end-products; CML, carboxymethyl-lysine; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP. FIGURE 2: Open in new tabDownload slide Increased expression of MG-AGE and CML. Immunohistochemical staining of visceral peritoneum showing a higher expression of MG-AGE (A, CML (B) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. Representative images of MG-AGE staining are given in (A) (right panel). Magnification ×600, scale bar represents 33 μm. MG, methylglyoxal; AGE, advanced glycation end-products; CML, carboxymethyl-lysine; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP. Serum protein fluorescence The serum protein fluorescence was increased in Glo1−/+ animals treated with high GDP-PDF compared with control: Glo1−/+C 3139 ± 203 versus Glo1−/+ + high GDP 4807 ± 714; P < 0.05 (Supplementary Table 1). Peritoneal inflammation There was a GDP-dependent increase in IL-6 expression in mice treated with PDF. Glo1−/+ mice treated with high GDP were found to have the highest level of IL-6 expression (IL-6 expression: WT + high GDP 6.91 ± 0.28 versus Glo1−/+ + high GDP 8.83 ± 0.27; P < 0.001; Figure 3). FIGURE 3: Open in new tabDownload slide Increased expression of IL-6 and VEGF, increased number of vessels. Immunohistochemical staining of visceral peritoneum showing a higher expression of IL-6 (A) and VEGF (B) as well as higher vessel count (C) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. IL-6, interleukin 6; VEGF, vascular endothelial growth factor; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP; $P < 0.05 versus WT high GDP. FIGURE 3: Open in new tabDownload slide Increased expression of IL-6 and VEGF, increased number of vessels. Immunohistochemical staining of visceral peritoneum showing a higher expression of IL-6 (A) and VEGF (B) as well as higher vessel count (C) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. IL-6, interleukin 6; VEGF, vascular endothelial growth factor; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP; $P < 0.05 versus WT high GDP. Peritoneal neovascularization WT mice treated with PDF had a dose-dependent increase of peritoneal VEGF score and vessels per area (Figure 3B and C). Untreated Glo1−/+ mice had a comparable VEGF score and number of vessels when compared with untreated WT mice. Treatment with PDF, in particular high GDP-PDF, led to a significant increase in vessels per area and VEGF staining (VEGF expression: WT + high GDP 6.91 ± 0.28 versus Glo1−/+ + high GDP 8.83 ± 0.27; P < 0.001; Figure 3). Peritoneal fibrosis and epithelial–mesenchymal transition WT mice treated with low GDP-PDF showed an increased submesothelial thickness when compared with WT sham: WT mice treated with high GDP-PDF showed an increase in thickness compared with WT mice treated with low GDP-PDF. A similar effect was also observed in Glo1−/+ mice. In comparison with WT mice, the submesothelial thickness of Glo1−/+ mice was markedly increased. A dose-dependent increase in TGF-β1 was also observed in the PD-treated mice, with the highest level of positive staining being observed in Glo1−/+ mice treated with high GDP-PDF (TGF-β1 expression: WT + high GDP 3.21 ± 0.27 versus Glo1−/+ + high GDP 5.52 ± 0.42; P < 0.001; Figure 4). Staining for vimentin, a marker of epithelial–mesenchymal transition, showed an increased level of staining in the Glo1−/+ mice treated with high GDP in comparison to controls (Figure 4). FIGURE 4: Open in new tabDownload slide Increased expression of TGF-β1, increased submesothelial thickness and increased expression of vimentin. Immunohistochemical staining of visceral peritoneum showing a higher expression of TGF-β1 (A) and vimentin (C—left panel) as well as thickened submesothelium (B) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. Representative images of vimentin staining are given in C (right panel). Magnification ×600, scale bar represents 33 μm. TGF-β1, transforming growth factor-β1; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. **P < 0.01 versus low GDP of the respective group; *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP; $P < 0.05 versus WT high GDP. FIGURE 4: Open in new tabDownload slide Increased expression of TGF-β1, increased submesothelial thickness and increased expression of vimentin. Immunohistochemical staining of visceral peritoneum showing a higher expression of TGF-β1 (A) and vimentin (C—left panel) as well as thickened submesothelium (B) in Glo1−/+ mice treated with high GDP containing PDF for 12 weeks. Representative images of vimentin staining are given in C (right panel). Magnification ×600, scale bar represents 33 μm. TGF-β1, transforming growth factor-β1; Glo1−/+, Glyoxalase 1-deficient; GDP, glucose degradation products; PDF, peritoneal dialysis fluid. **P < 0.01 versus low GDP of the respective group; *P < 0.05 versus low GDP of the respective group; ###P < 0.001 versus Control of the respective group; ##P < 0.01 versus Control of the respective group; #P < 0.05 versus Control of the respective group; $$P < 0.01 versus WT high GDP; $P < 0.05 versus WT high GDP. Peritoneal function PET analysis indicated that the Glo1−/+ high GDP-PDF revealed a faster transport type compared with control (D/Purea: Glo1−/+ C 0.58 ± 0.05 versus Glo1−/+ + high GDP 0.87 ± 0.04; P < 0.01; Table 3). Table 3. Peritoneal equilibration test . D/PCreatinine . D/PUrea . WT C 0.50 ± 0.04 0.57 ± 0.02 WT IP 0.52 ± 0.04 0.66 ± 0.03 WT + low GDP 0.58 ± 0.05 0.72 ± 0.03# WT + high GDP 0.61 ± 0.03 0.73 ± 0.04# Glo1−/+ C 0.50 ± 0.04 0.58 ± 0.05 Glo1−/+ IP 0.52 ± 0.05 0.69 ± 0.03 Glo1−/+ + low GDP 0.59 ± 0.04 0.74 ± 0.04 Glo1−/+ + high GDP 0.69 ± 0.04# 0.87 ± 0.04## . D/PCreatinine . D/PUrea . WT C 0.50 ± 0.04 0.57 ± 0.02 WT IP 0.52 ± 0.04 0.66 ± 0.03 WT + low GDP 0.58 ± 0.05 0.72 ± 0.03# WT + high GDP 0.61 ± 0.03 0.73 ± 0.04# Glo1−/+ C 0.50 ± 0.04 0.58 ± 0.05 Glo1−/+ IP 0.52 ± 0.05 0.69 ± 0.03 Glo1−/+ + low GDP 0.59 ± 0.04 0.74 ± 0.04 Glo1−/+ + high GDP 0.69 ± 0.04# 0.87 ± 0.04## WT, wild-type; Glo1−/+, Glyoxalase 1-deficient; C, control; IP, intraperitoneal injection; GDP, glucose degradation products; PDF, peritoneal dialysis fluid; D, dialysate; P, plasma. #P < 0.05 versus Control of the respective group. ##P < 0.01 versus Control of the respective group. Open in new tab Table 3. Peritoneal equilibration test . D/PCreatinine . D/PUrea . WT C 0.50 ± 0.04 0.57 ± 0.02 WT IP 0.52 ± 0.04 0.66 ± 0.03 WT + low GDP 0.58 ± 0.05 0.72 ± 0.03# WT + high GDP 0.61 ± 0.03 0.73 ± 0.04# Glo1−/+ C 0.50 ± 0.04 0.58 ± 0.05 Glo1−/+ IP 0.52 ± 0.05 0.69 ± 0.03 Glo1−/+ + low GDP 0.59 ± 0.04 0.74 ± 0.04 Glo1−/+ + high GDP 0.69 ± 0.04# 0.87 ± 0.04## . D/PCreatinine . D/PUrea . WT C 0.50 ± 0.04 0.57 ± 0.02 WT IP 0.52 ± 0.04 0.66 ± 0.03 WT + low GDP 0.58 ± 0.05 0.72 ± 0.03# WT + high GDP 0.61 ± 0.03 0.73 ± 0.04# Glo1−/+ C 0.50 ± 0.04 0.58 ± 0.05 Glo1−/+ IP 0.52 ± 0.05 0.69 ± 0.03 Glo1−/+ + low GDP 0.59 ± 0.04 0.74 ± 0.04 Glo1−/+ + high GDP 0.69 ± 0.04# 0.87 ± 0.04## WT, wild-type; Glo1−/+, Glyoxalase 1-deficient; C, control; IP, intraperitoneal injection; GDP, glucose degradation products; PDF, peritoneal dialysis fluid; D, dialysate; P, plasma. #P < 0.05 versus Control of the respective group. ##P < 0.01 versus Control of the respective group. Open in new tab DISCUSSION In this study, it has been shown that mice deficient in Glo1, an enzyme that is part of the glyoxalase system and the major route for the detoxification of the dicarbonyls MG and Gx, are more susceptible to PDF-induced peritoneal damage when compared with WT mice. Treatment with PDF for 3 months showed that Glo1−/+ mice had increased loss of peritoneal function and increased fibrosis, inflammation and angiogenesis, which was dependent upon the GDP load of the PDF used. These data suggest that within the context of PD, the level of Glo1 activity provides a previously unrecognized protective mechanism against the failure of long-term PD. It has previously been shown that there is a time-dependent association between GDP and the accumulation of AGE in the peritoneal membrane of patients undergoing PD [17, 18], which is supported, in part, by the findings of this study. It was shown that there was increased accumulation of both MG- and Gx-derived AGE within the peritoneal membrane as the content of GDPs in the PDF increased. This would suggest that the on-going peritoneal damage observed in patients undergoing PD is in part caused by the highly toxic nature of GDP. However, it is imperative to establish which component of GDP is responsible for the biological effects observed. The concentration of dicarbonyls in PDF has been reported [39]. It has been shown that the concentration of 3-DG, Gx and MG found in PDF are within a micro-molar range (1–200 µM), with the levels of the 3-DG being ∼100-fold higher than either Gx or MG [2–11]. It is not surprising to find that the concentration of 3-DG is higher; based upon the non-enzymatic fragmentation of glucose, with the order of dicarbonyl production from glucose is Gx > 3-DG > MG [37]. However, with respect to potency, 3-DG is a poor post-translational modifier of proteins. In contrast, while the concentration of MG and Gx in PDF is low, their potency to react with proteins is significantly higher, suggesting that these dicarbonyls are key mediators of the peritoneal damage observed with PDF. This is supported, in part, by the central finding of this study that the loss of Glo1 leads to increased peritoneal damage in response to PDF, as both MG and Gx are the major substrates for Glo1, whereas 3-DG is not [24]. It is interesting to note that the level of CML, a major adduct of Gx, within the peritoneal membrane was significantly higher than the MG-derived AGE. This would suggest that the concentration of Gx within the PDF was higher than MG, which is consistent with our data and previous estimates [39]. However, as Gx is also generated from lipid peroxidation, it may also be suggestive of increased oxidative stress. It has been reported that a primary target of protein modification by MG is the mitochondria [27], leading increased production of ROS and potentially increased lipid peroxidation. This secondary mechanism resulting from increased exposure to MG could also be active within the peritoneal membrane, leading to further modification and damage by Gx. Additional experiments are required to further define the association between increased post-translational modification by dicarbonyls and observed activation and increase in inflammation. In this regard, it is interesting to note that the expression of the RAGE was increased in WT and Glo1−/+ mice following treatment with PDF. This cell-surface receptor has previously been shown to interact and bind to AGE-modified proteins, leading to an enhanced inflammatory response [15, 40]. Other RAGE ligands have been described subsequently, including RAGE to possess a multi-ligand nature and have been termed a ‘pattern recognition’ receptor due to the diverse variety of the ligands that bind and transmit cellular signalling through RAGE. These ligands, in addition to AGEs, include members of the s100/calgranulin family, HMGB1 (high-mobility group box-1), amyloid fibrils and the counter-receptor for β-integrins, Mac-1. Although the levels of these ligands were not determined in this study, activation of RAGE is associated with decreased expression of Glo1; induction of diabetes in WT mice decreased expression of Glo1 whereas induction of diabetes in RAGE−/− mice did not [40]. The molecular mechanism which underlies this association has yet to be fully understood. Nevertheless, studies involving the blocking of RAGE provide that RAGE is also an important factor in GDP-induced peritoneal damage [15, 41]. In recent years, many approaches have been introduced to lower peritoneal toxicity of PDF. Blocking growth factors, such as TGF-β1 [42], and the administration of anti-fibrotic drugs, such as rosiglitazone [43], have been reported to be successful in this regard. However, less attention has been given to the potential modulation of a patient's native detoxifying systems. It has been shown that the peritoneal membrane can be protected against PDF-induced damage by high glucose by treatment with benfotiamine, an analogy of thiamine and cofactor for transketolase [20]. Increased transketolase activity, in vitro and in vivo, has been shown to prevent the accumulation of MG by activation of the pentose-phosphate pathway, which shifts glycolytic flux away from the accumulation of triose phosphates (glyceraldeyhde-3-phosphate and dihydroxyacetone phosphate), the precursors of MG, into the formation of ribose-5-phosphate [44–46]. The use of benfotiamine may therefore be an effective therapeutic option in PD; however, its usefulness would be limited in the context of PD by only addressing the direct effect of high glucose from PDF and not the effect of the GDPs MG and Gx. A more direct approach could include the administration of GSH, a scavenger of dicarbonyls and cofactor for the glyoxalase system. It has been shown, in vitro, that supplementation of PDF with GSH can reduce the content of dicarbonyls [31]. Furthermore, it has been reported that PD patients are deficient in GSH [47, 48]. Thus, administration of GSH, in particular esterified GSH which is more cell permeable, may help boost a patient's native Glo1 activity by providing an excess of the cofactor. As GSH is also a potent antioxidant, it would also provide a means of reducing an oxidative stress that may also be generated from the PDF. A more effective scavenger of dicarbonyls is aminoguandine, which has been shown in vitro to be more effective than GSH in reducing the content of dicarbonyls in PDF [31, 49]. Aminoguanidine is also an inhibitor of ROS formation by divalent metal chelation [50], and this appears to be more important than scavenging of dicarbonyls in the observed effects [51]. However, aminoguanidine could only be used prior to administration of a PDF to a patient, as studies have shown that it has significant side-effects at clinically relevant concentrations [52]. Nevertheless, the findings of this study identify for the first time in vivo a pivotal role for Glo1 as a detoxifying enzyme in GDP-associated peritoneal toxicity in PD. The indirect and direct modulation of Glo1 may therefore offer a new therapeutic option in prevention of GDP-induced peritoneal damage in PD. AUTHORS’ CONTRIBUTIONS L.P.K., S.H., S.S., S.M.K. and L.E.B. participated in the research design, performance of the research, data analysis and writing of the manuscript. P.P.N, M.B., M.Z., T.F. and V.S. participated in the research design and writing of the manuscript. FUNDING The study was supported in part by grants of the Deutsche Forschungsgemeinschaft (1469/3-1 to V.S.), the Dietmar-Hopp-Stiftung (to P.P.N.), the Deutsche Forschungsgemeinschaft (SFB 1118 to P.P.N.) and the European Nephrology and Dialysis Institute (to V.S.). CONFLICT OF INTEREST STATEMENT None declared. ACKNOWLEDGEMENTS We thank Ms Janine Straeter for her technical assistance. REFERENCES 1 Williams JD , Craig KJ , Topley N , et al. Morphologic changes in the peritoneal membrane of patients with renal disease , J Am Soc Nephrol , 2002 , vol. 13 (pg. 470 - 479 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 2 Erixon M , Wieslander A , Linden T , et al. How to avoid glucose degradation products in peritoneal dialysis fluids , Perit Dial Int , 2006 , vol. 26 (pg. 490 - 497 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 3 Jorres A , Bender TO , Witowski J . Glucose degradation products and the peritoneal mesothelium , Perit Dial Int , 2000 , vol. 20 Suppl 5 (pg. S19 - S22 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 4 Lage C , Pischetsrieder M , Aufricht C , et al. First in vitro and in vivo experiences with Stay-Safe Balance, a pH-neutral solution in a dual-chambered bag , Perit Dial Int , 2000 , vol. 20 Suppl 5 (pg. S28 - S32 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 5 Mittelmaier S , Funfrocken M , Fenn D , et al. Quantification of the six major alpha-dicarbonyl contaminants in peritoneal dialysis fluids by UHPLC/DAD/MSMS , Anal Bioanal Chem , 2011 , vol. 401 (pg. 1183 - 1193 ) Google Scholar Crossref Search ADS PubMed WorldCat 6 Nilsson-Thorell CB , Muscalu N , Andren AH , et al. Heat sterilization of fluids for peritoneal dialysis gives rise to aldehydes , Perit Dial Int , 1993 , vol. 13 (pg. 208 - 213 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 7 Rippe B , Simonsen O , Heimburger O , et al. Long-term clinical effects of a peritoneal dialysis fluid with less glucose degradation products , Kidney Int , 2001 , vol. 59 (pg. 348 - 357 ) Google Scholar Crossref Search ADS PubMed WorldCat 8 Schalkwijk CG , Posthuma N , ten Brink HJ , et al. Induction of 1,2-dicarbonyl compounds, intermediates in the formation of advanced glycation end-products, during heat-sterilization of glucose-based peritoneal dialysis fluids , Perit Dial Int , 1999 , vol. 19 (pg. 325 - 333 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 9 Schalkwijk CG , ter Wee PM , Teerlink T . Reduced 1,2-dicarbonyl compounds in bicarbonate/lactate-buffered peritoneal dialysis (PD) fluids and PD fluids based on glucose polymers or amino acids , Perit Dial Int , 2000 , vol. 20 (pg. 796 - 798 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 10 Wieslander A , Forsback G , Svensson E , et al. Cytotoxicity, pH, and glucose degradation products in four different brands of PD fluid , Adv Perit Dial , 1996 , vol. 12 (pg. 57 - 60 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 11 Wieslander AP , Deppisch R , Svensson E , et al. In vitro biocompatibility of a heat-sterilized, low-toxic, and less acidic fluid for peritoneal dialysis , Perit Dial Int , 1995 , vol. 15 (pg. 158 - 164 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 12 Thornalley PJ . Protein and nucleotide damage by glyoxal and methylglyoxal in physiological systems—role in ageing and disease , Drug Metabol Drug Interact , 2008 , vol. 23 (pg. 125 - 150 ) Google Scholar Crossref Search ADS PubMed WorldCat 13 Morgan LW , Wieslander A , Davies M , et al. Glucose degradation products (GDP) retard remesothelialization independently of d-glucose concentration , Kidney Int , 2003 , vol. 64 (pg. 1854 - 1866 ) Google Scholar Crossref Search ADS PubMed WorldCat 14 Witowski J , Wisniewska J , Korybalska K , et al. Prolonged exposure to glucose degradation products impairs viability and function of human peritoneal mesothelial cells , J Am Soc Nephrol , 2001 , vol. 12 (pg. 2434 - 2441 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 15 Schwenger V , Morath C , Salava A , et al. Damage to the peritoneal membrane by glucose degradation products is mediated by the receptor for advanced glycation end-products , J Am Soc Nephrol , 2006 , vol. 17 (pg. 199 - 207 ) Google Scholar Crossref Search ADS PubMed WorldCat 16 Mortier S , Faict D , Lameire NH , et al. Benefits of switching from a conventional to a low-GDP bicarbonate/lactate-buffered dialysis solution in a rat model , Kidney Int , 2005 , vol. 67 (pg. 1559 - 1565 ) Google Scholar Crossref Search ADS PubMed WorldCat 17 Mortier S , Faict D , Schalkwijk CG , et al. Long-term exposure to new peritoneal dialysis solutions: Effects on the peritoneal membrane , Kidney Int , 2004 , vol. 66 (pg. 1257 - 1265 ) Google Scholar Crossref Search ADS PubMed WorldCat 18 Kihm LP , Wibisono D , Muller-Krebs S , et al. RAGE expression in the human peritoneal membrane , Nephrol Dial Transplant , 2008 , vol. 23 (pg. 3302 - 3306 ) Google Scholar Crossref Search ADS PubMed WorldCat 19 Guo H , Leung JC , Lam MF , et al. Smad7 transgene attenuates peritoneal fibrosis in uremic rats treated with peritoneal dialysis , J Am Soc Nephrol , 2007 , vol. 18 (pg. 2689 - 2703 ) Google Scholar Crossref Search ADS PubMed WorldCat 20 Kihm LP , Muller-Krebs S , Klein J , et al. Benfotiamine protects against peritoneal and kidney damage in peritoneal dialysis , J Am Soc Nephrol , 2011 , vol. 22 (pg. 914 - 926 ) Google Scholar Crossref Search ADS PubMed WorldCat 21 Hirahara I , Kusano E , Yanagiba S , et al. Peritoneal injury by methylglyoxal in peritoneal dialysis , Perit Dial Int , 2006 , vol. 26 (pg. 380 - 392 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 22 Rabbani N , Thornalley PJ . Methylglyoxal, glyoxalase 1 and the dicarbonyl proteome , Amino Acids , 2012 , vol. 42 (pg. 1133 - 1142 ) Google Scholar Crossref Search ADS PubMed WorldCat 23 Bierhaus A , Fleming T , Stoyanov S , et al. Methylglyoxal modification of Nav1.8 facilitates nociceptive neuron firing and causes hyperalgesia in diabetic neuropathy , Nat Med , 2012 , vol. 18 (pg. 926 - 933 ) Google Scholar Crossref Search ADS PubMed WorldCat 24 Thornalley PJ . Glyoxalase I—structure, function and a critical role in the enzymatic defence against glycation , Biochem Soc Trans , 2003 , vol. 31 Pt 6 (pg. 1343 - 1348 ) Google Scholar Crossref Search ADS PubMed WorldCat 25 Abordo EA , Minhas HS , Thornalley PJ . Accumulation of alpha-oxoaldehydes during oxidative stress: a role in cytotoxicity , Biochem Pharmacol , 1999 , vol. 58 (pg. 641 - 648 ) Google Scholar Crossref Search ADS PubMed WorldCat 26 Rabbani N , Thornalley PJ . Dicarbonyls linked to damage in the powerhouse: glycation of mitochondrial proteins and oxidative stress , Biochem Soc Trans , 2008 , vol. 36 Pt 5 (pg. 1045 - 1050 ) Google Scholar Crossref Search ADS PubMed WorldCat 27 Morcos M , Du X , Pfisterer F , et al. Glyoxalase-1 prevents mitochondrial protein modification and enhances lifespan in Caenorhabditis elegans , Aging Cell , 2008 , vol. 7 (pg. 260 - 269 ) Google Scholar Crossref Search ADS PubMed WorldCat 28 Fleming TH , Theilen TM , Masania J , et al. Aging-dependent reduction in glyoxalase 1 delays wound healing , Gerontology , 2013 , vol. 59 (pg. 427 - 437 ) Google Scholar Crossref Search ADS PubMed WorldCat 29 Giacco F , Du X , D'Agati VD , et al. Knockdown of glyoxalase 1 mimics diabetic nephropathy in nondiabetic mice , Diabetes , 2014 , vol. 63 (pg. 291 - 299 ) Google Scholar Crossref Search ADS PubMed WorldCat 30 Inagi R , Miyata T , Ueda Y , et al. Efficient in vitro lowering of carbonyl stress by the glyoxalase system in conventional glucose peritoneal dialysis fluid , Kidney Int , 2002 , vol. 62 (pg. 679 - 687 ) Google Scholar Crossref Search ADS PubMed WorldCat 31 Korybalska K , Wisniewska-Elnur J , Trominska J , et al. The role of the glyoxalase pathway in reducing mesothelial toxicity of glucose degradation products , Perit Dial Int , 2006 , vol. 26 (pg. 259 - 265 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 32 El-Osta A , Brasacchio D , Yao D , et al. Transient high glucose causes persistent epigenetic changes and altered gene expression during subsequent normoglycemia , J Exp Med , 2008 , vol. 205 (pg. 2409 - 2417 ) Google Scholar Crossref Search ADS PubMed WorldCat 33 Muller-Krebs S , Kihm LP , Zeier B , et al. Renal toxicity mediated by glucose degradation products in a rat model of advanced renal failure , Eur J Clin Invest , 2008 , vol. 38 (pg. 296 - 305 ) Google Scholar Crossref Search ADS PubMed WorldCat 34 La Milia V , Di Filippo S , Crepaldi M , et al. Mini-peritoneal equilibration test: a simple and fast method to assess free water and small solute transport across the peritoneal membrane , Kidney Int , 2005 , vol. 68 (pg. 840 - 846 ) Google Scholar Crossref Search ADS PubMed WorldCat 35 Rippe B . How to assess transport in animals? , Perit Dial Int , 2009 , vol. 29 Suppl 2 (pg. S32 - S35 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 36 McLellan AC , Phillips SA , Thornalley PJ . The assay of methylglyoxal in biological systems by derivatization with 1,2-diamino-4,5-dimethoxybenzene , Anal Biochem , 1992 , vol. 206 (pg. 17 - 23 ) Google Scholar Crossref Search ADS PubMed WorldCat 37 Bradford MM . A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding , Anal Biochem , 1976 , vol. 72 (pg. 248 - 254 ) Google Scholar Crossref Search ADS PubMed WorldCat 38 McLellan AC , Thornalley PJ . Glyoxalase activity in human red blood cells fractioned by age , Mech Ageing Dev , 1989 , vol. 48 (pg. 63 - 71 ) Google Scholar Crossref Search ADS PubMed WorldCat 39 Erixon M , Linden T , Kjellstrand P , et al. PD fluids contain high concentrations of cytotoxic GDPs directly after sterilization , Perit Dial Int , 2004 , vol. 24 (pg. 392 - 398 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 40 Bierhaus A , Nawroth PP . Multiple levels of regulation determine the role of the receptor for AGE (RAGE) as common soil in inflammation, immune responses and diabetes mellitus and its complications , Diabetologia , 2009 , vol. 52 (pg. 2251 - 2263 ) Google Scholar Crossref Search ADS PubMed WorldCat 41 Muller-Krebs S , Kihm LP , Madhusudhan T , et al. Human RAGE antibody protects against AGE-mediated podocyte dysfunction , Nephrol Dial Transplant , 2012 , vol. 27 (pg. 3129 - 3136 ) Google Scholar Crossref Search ADS PubMed WorldCat 42 Loureiro J , Aguilera A , Selgas R , et al. Blocking TGF-beta1 protects the peritoneal membrane from dialysate-induced damage , J Am Soc Nephrol , 2011 , vol. 22 (pg. 1682 - 1695 ) Google Scholar Crossref Search ADS PubMed WorldCat 43 Sandoval P , Loureiro J , Gonzalez-Mateo G , et al. PPAR-gamma agonist rosiglitazone protects peritoneal membrane from dialysis fluid-induced damage , Lab Invest , 2010 , vol. 90 (pg. 1517 - 1532 ) Google Scholar Crossref Search ADS PubMed WorldCat 44 Hammes HP , Du X , Edelstein D , et al. Benfotiamine blocks three major pathways of hyperglycemic damage and prevents experimental diabetic retinopathy , Nat Med , 2003 , vol. 9 (pg. 294 - 299 ) Google Scholar Crossref Search ADS PubMed WorldCat 45 Rabbani N , Alam SS , Riaz S , et al. High-dose thiamine therapy for patients with type 2 diabetes and microalbuminuria: a randomised, double-blind placebo-controlled pilot study , Diabetologia , 2009 , vol. 52 (pg. 208 - 212 ) Google Scholar Crossref Search ADS PubMed WorldCat 46 Karachalias N , Babaei-Jadidi R , Rabbani N , et al. Increased protein damage in renal glomeruli, retina, nerve, plasma and urine and its prevention by thiamine and benfotiamine therapy in a rat model of diabetes , Diabetologia , 2010 , vol. 53 (pg. 1506 - 1516 ) Google Scholar Crossref Search ADS PubMed WorldCat 47 Ross EA , Koo LC , Moberly JB . Low whole blood and erythrocyte levels of glutathione in hemodialysis and peritoneal dialysis patients , Am J Kidney Dis , 1997 , vol. 30 (pg. 489 - 494 ) Google Scholar Crossref Search ADS PubMed WorldCat 48 Yamamoto T , Tomo T , Okabe E , et al. Glutathione depletion as a mechanism of 3,4-dideoxyglucosone-3-ene-induced cytotoxicity in human peritoneal mesothelial cells: role in biocompatibility of peritoneal dialysis fluids , Nephrol Dial Transplant , 2009 , vol. 24 (pg. 1436 - 1442 ) Google Scholar Crossref Search ADS PubMed WorldCat 49 Miyata T , Ueda Y , Asahi K , et al. Mechanism of the inhibitory effect of OPB-9195 [(+/−)-2-isopropylidenehydrazono-4-oxo-thiazolidin-5-yla cetanilide] on advanced glycation end product and advanced lipoxidation end product formation , J Am Soc Nephrol , 2000 , vol. 11 (pg. 1719 - 1725 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 50 Price DL , Rhett PM , Thorpe SR , et al. Chelating activity of advanced glycation end-product inhibitors , J Biol Chem , 2001 , vol. 276 (pg. 48967 - 48972 ) Google Scholar Crossref Search ADS PubMed WorldCat 51 Dyer DG , Blackledge JA , Thorpe SR , et al. Formation of pentosidine during nonenzymatic browning of proteins by glucose. Identification of glucose and other carbohydrates as possible precursors of pentosidine in vivo , J Biol Chem , 1991 , vol. 266 (pg. 11654 - 11660 ) Google Scholar PubMed OpenURL Placeholder Text WorldCat 52 Thornalley PJ . Use of aminoguanidine (Pimagedine) to prevent the formation of advanced glycation endproducts , Arch Biochem Biophys , 2003 , vol. 419 (pg. 31 - 40 ) Google Scholar Crossref Search ADS PubMed WorldCat © The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.
TI - Increased peritoneal damage in glyoxalase 1 knock-down mice treated with peritoneal dialysis
JF - Nephrology Dialysis Transplantation
DO - 10.1093/ndt/gfu346
DA - 2015-03-01
UR - https://www.deepdyve.com/lp/oxford-university-press/increased-peritoneal-damage-in-glyoxalase-1-knock-down-mice-treated-D81cFFyGgI
SP - 401
EP - 409
VL - 30
IS - 3
DP - DeepDyve
ER -