Tissue Sodium Accumulation Induces Organ Inflammation and Injury in Chronic Kidney Disease.

High salt intake is a primary cause of over-hydration in chronic kidney disease (CKD) patients. Inflammatory markers are predictors of CKD mortality; however, the pathogenesis of inflammation remains unclear. Sodium storage in tissues has recently emerged as an issue of concern. The binding of sodium to tissue glycosaminoglycans and its subsequent release regulates local tonicity. Many cell types express tonicity-responsive enhancer-binding protein (TonEBP), which is activated in a tonicity-dependent or tonicity-independent manner. Macrophage infiltration was observed in the heart, peritoneal wall, and para-aortic tissues in salt-loading subtotal nephrectomized mice, whereas macrophages were not prominent in tap water-loaded subtotal nephrectomized mice. TonEBP was increased in the heart and peritoneal wall, leading to the upregulation of inflammatory mediators associated with cardiac fibrosis and peritoneal membrane dysfunction, respectively. Reducing salt loading by a diuretic treatment or changing to tap water attenuated macrophage infiltration, TonEBP expression, and inflammatory marker expression. The role of TonEBP may be crucial during the cardiac fibrosis and peritoneal deterioration processes induced by sodium overload. Anti-interleukin-6 therapy improved cardiac inflammation and fibrosis and peritoneal membrane dysfunction. Further studies are necessary to establish a strategy to regulate organ dysfunction induced by TonEBP activation in CKD patients.

Interleukin-6 blockade reduces salt-induced cardiac inflammation and fibrosis in subtotal nephrectomized mice.

Cardiovascular disease is the most common comorbidity in patients with chronic kidney disease (CKD), affecting both their prognosis and quality of life. Cardiac fibrosis is common in patients with CKD with left ventricular diastolic dysfunction, and it is associated with increased risk of heart failure and mortality. Recent evidence suggests that high salt intake activates immune responses associated with local accumulation of sodium. We reported that high salt intake promotes cardiac inflammation in subtotal nephrectomized (Nx) mice. We investigated the effects of administration of MR16-1, a rat anti-mouse monoclonal interleukin (IL)-6 receptor antibody, in Nx mice with salt loading (Nx-salt). Expression of monocyte chemoattractant protein-1, tumor necrosis factor-α, IL-1ß, and IL-6 mRNAs and macrophage infiltration was significantly reduced in the heart of Nx-salt mice treated with MR16-1 (Nx-salt-MR16-1) compared with Nx-salt mice treated with control rat rat IgG1 (Nx-salt-rat IgG1). Correspondingly, cardiac fibrosis was significantly attenuated in Nx-salt-MR16-1 mice compared with Nx-salt-rat IgG1 mice. Furthermore, in the heart of Nx-salt-MR16-1 mice, expression of mRNA for nicotinamide adenine dinucleotide phosphate oxidase-2, an oxidative stress marker, was significantly downregulated compared with Nx-salt-rat IgG1 mice. Increases in cardiac metabolites, including histidine and γ-butyrobetaine, were also reversed by IL-6 blockade treatment. In conclusion, IL-6 blockade exerts anti-inflammatory, antifibrotic, and partial antioxidative effects in the heart of Nx-salt mice.NEW & NOTEWORTHY In the present study, IL-6 blockade exerted anti-inflammatory, antifibrotic, and partial antioxidative effects on the hearts of mice with CKD on a high-salt diet. Therefore, IL-6 potentially mediates cardiac fibrosis induced by high salt intake in patients with CKD, a finding with therapeutic implications. Of note, the next therapeutic implication may simply be the reinforcement of low-salt diets or diuretics and further research on the anti-inflammatory effects of these measures rather than IL-6 blockade with high-salt diet.

Successful Introduction of Peritoneal Dialysis in an End-stage Renal Failure Patient with Idiopathic Aplastic Anemia.

A 45-year-old man with idiopathic aplastic anemia required renal replacement therapy (RRT) due to end-stage renal disease (ESRD). We succeeded in inserting the peritoneal dialysis (PD) catheter under cover of frequent red blood cell and platelet infusions because of severe pancytopenia. During the one-year period after starting PD using an ultraviolet-ray sterilization device, he developed severe leukopenia but no PD-related peritonitis or exit site/tunnel infection until he died of pneumonia. This case suggests that PD might be a suitable choice as RRT in ESRD patients with aplastic anemia, even in those with severe pancytopenia.

Excessive salt intake increases peritoneal solute transport rate via local tonicity-responsive enhancer binding protein in subtotal nephrectomized mice.

BACKGROUND: High peritoneal transport is associated with high mortality and technical failure in peritoneal dialysis (PD). Baseline peritoneal solute transport rate (PSTR) as measured by the peritoneal equilibration test (PET) within 6 months after PD initiation varies between patients. Sodium is reported to be stored in the skin or muscle of dialysis patients. This study investigated whether excessive salt intake in uremic mice caused peritoneal alterations without exposure to PD fluid. METHODS: Sham-operated (Sham) and subtotal nephrectomized (Nx) mice were randomly given tap water or 1% sodium chloride (NaCl)-containing water for 8 weeks. PET was then performed to evaluate peritoneal function. Human mesothelial cell line Met-5A was used for in vitro studies. RESULTS: We observed higher PSTR in Nx mice with 1% NaCl-containing drinking water (Nx + salt) compared with those with tap water (Nx + water), along with enhanced angiogenesis and inflammation in the peritoneum. Blockade of interleukin (IL)-6 signaling rescued peritoneal transport function in Nx + salt mice. In cultured Met-5A, additional NaCl in the medium upregulated IL-6 as well as vascular endothelial growth factor-A, associated with increased expression and nuclear translocation of tonicity-responsive enhancer binding protein (TonEBP). Knockdown of TonEBP lowered the induction caused by high tonicity. Peritoneal TonEBP expression was higher in Nx + salt mice, while removal of high-salt diet lowered TonEBP level and improved peritoneal transport function. CONCLUSIONS: Excessive dietary salt intake caused peritoneal membrane functional and structural changes under uremic status. TonEBP regulated hypertonicity-related inflammatory changes and might play a crucial role in high baseline peritoneal transport.

Increase of Eosinophil in Dialysate During Induction of Peritoneal Dialysis.

As a rare complication in patients on peritoneal dialysis (PD), increase of eosinophil (peritoneal dialysate fluid [PDF] eosinophilia), including eosinophilic peritonitis, was observed in PDF. The majority of eosinophilic peritonitis cases are detected during the early phase of PD induction. However, the frequency of and mechanisms underlying PDF eosinophilia remain unclear. We therefore investigated the frequency of PDF eosinophilia and what mechanisms, specifically complement activation, might contribute to its occurrence. In 48 patients, eosinophil counts and concentrations of complement activation products, such as C3a, C5a, and sC5b-9, interleukin (IL)-5, and IL-6 in PDF were evaluated on days 1, 2, and 4 after starting PD therapy. We focused on the relationships between patient background characteristics and eosinophil counts and levels of C3a, C5a, and sC5b-9 as complement activation products in PDF. In 33.3% of PD patients, increased PDF eosinophils were observed on day 1. Eosinophil counts correlated with PDF levels of C3a on days 1 and 2, IL-5 on days 1, 2, and 4, and IL-6 on day 1. In terms of background characteristics, only the duration the PD catheter was left in place differed significantly between PDF eosinophilia and non-PDF eosinophilia. Notably, PDF levels of C3a differed significantly between patients with and without eosinophilia, suggesting that C3a might be a candidate for induction of increased eosinophil.PDF eosinophilia was frequently observed during PD initiation. Our results suggest that PD catheter insertion and complement activation might be related to increases in eosinophils in PDF during PD initiation.

Differences in peritoneal solute transport rates in peritoneal dialysis.

BACKGROUND: Ultrafiltration failure associated with peritoneal membrane dysfunction is one of the main complications for patients on long-term peritoneal dialysis (PD). The dialysate-to-plasma concentration ratio (D/P) of creatinine is widely used to assess peritoneal membrane function. However, other small-sized solutes have not been studied in detail as potential indicators of peritoneal permeability. METHODS: We studied the D/Ps of small, middle-sized and large molecules in peritoneal equilibration tests in 50 PD patients. We applied metabolomic analysis of comprehensive small molecular metabolites using capillary electrophoresis time-of-flight mass spectrometry. RESULTS: D/Ps of middle-sized and large molecules correlated positively with D/P creatinine. Most D/Ps of small molecules correlated positively with D/P creatinine. Among 38 small molecules contained in the dialysate, urea, citrulline and choline showed significantly lower ability to permeate than creatinine. In the relationship between D/Ps of creatinine and small molecules, regression coefficients of three molecules were less than 0.3, representing no correlation to D/P creatinine. Five molecules showed negative regression coefficients. Among these molecules, hippurate and 3-indoxyl sulfate showed relatively high teinpro binding rates, which may affect permeability. Serum concentrations of two molecules were higher in the Low Kt/V group, mainly due to high protein binding rates. CONCLUSIONS: D/Ps of some molecules did not correlate with D/P creatinine. Factors other than molecular weight, such as charge and protein binding rate, are involved in peritoneal transport rates. Metabolomic analysis appears useful to analyze small molecular uremic toxins, which could accumulate in PD patients, and the status of peritoneal membrane transport for each molecule.

Effects of long-term treatment with low-GDP, pH-neutral solutions on peritoneal membranes in peritoneal dialysis patients.

BACKGROUND: The morphological changes induced by bio-incompatible peritoneal dialysis (PD) solutions are well known. However, the morphological damage induced by long-term low-glucose degradation product (GDP), pH-neutral solutions has not been reported in detail. The aim of this study was to investigate the long-term effects of pH-neutral PD solutions on morphological and functional changes in the peritoneal membrane. METHODS: We assessed peritoneal membrane biopsy samples from PD patients treated with acidic (Conventional group) or pH-neutral solutions (pH-neutral group) using pathology and immunopathology techniques. RESULTS: Analyses of 54 Conventional and 73 pH-neutral group samples showed that the peritoneal membrane was thicker (P < 0.001), the ratio of luminal diameter to vessel diameter (L/V ratio) was significantly smaller (P < 0.001), and advanced glycation end-product (AGE) accumulation was higher in the Conventional than in the pH-neutral group (P < 0.001). Comparison of samples from patients in the Conventional (n = 33) and pH-neutral groups (n = 33) who were treated for 4-10 years also showed significant differences in peritoneal thickness, L/V ratio and AGE score. Furthermore, the L/V ratio in the Conventional group significantly decreased over time (P < 0.01); however, no such change was seen in the pH-neutral group. Peritoneal membrane thickness was not associated with PD duration in both groups. Dialysate-to-plasma ratio of creatinine and L/V ratio negatively correlated with PD treatment duration in the Conventional group, but not in the pH-neutral group. CONCLUSIONS: These findings suggest that pH-neutral solutions prevent the morphological and functional peritoneal changes induced by long-term PD treatment.

Anti-C5a complementary peptide mitigates zymosan-induced severe peritonitis with fibrotic encapsulation in rats pretreated with methylglyoxal.

In a previous study of fungal peritoneal injury in peritoneal dialysis patients, complement (C)-dependent pathological changes were developed in zymosan (Zy)-induced peritonitis by peritoneal scraping. However, the injuries were limited to the parietal peritoneum and did not show any fibrous encapsulation of the visceral peritoneum, which differs from human encapsular peritoneal sclerosis (EPS). We investigated peritoneal injury in a rat model of Zy-induced peritonitis pretreated with methylglyoxal (MGO) instead of scraping (Zy/MGO peritonitis) to clarify the role of C in the process of fibrous encapsulation of the visceral peritoneum. Therapeutic effects of an anti-C5a complementary peptide, AcPepA, on peritonitis were also studied. In Zy/MGO peritonitis, peritoneal thickness, fibrin exudation, accumulation of inflammatory cells, and deposition of C3b and C5b-9 with loss of membrane C regulators were increased along the peritoneum until day 5. On day 14, fibrous encapsulation of the visceral peritoneum was observed, resembling human EPS. Peritoneal injuries and fibrous changes were significantly improved with AcPepA treatment, even when AcPepA was administered following injection of Zy in Zy/MGO peritonitis. The data show that C5a might play a role in the development of encapsulation-like changes in the visceral peritoneum in Zy/MGO peritonitis. AcPepA might have therapeutic effects in fungal infection-induced peritoneal injury by preventing subsequent development of peritoneal encapsulation.

TGF-ß1-VEGF-A pathway induces neoangiogenesis with peritoneal fibrosis in patients undergoing peritoneal dialysis.

The characteristic features of chronic peritoneal injury with peritoneal dialysis (PD) are submesothelial fibrosis and neoangiogenesis. Transforming growth factor (TGF)ß and vascular endothelial growth factor (VEGF)-A are the main mediators of fibrosis and neoangiogenesis, respectively; however, the effect of the interaction between them on the peritoneum is not well known. In this study, we investigated the relationship between TGF-ß1 and VEGF-A in inducing peritoneal fibrosis by use of human tissues and dialysate, cultured cells, and animal models. The VEGF-A concentration correlated with the dialysate-to-plasma ratio of creatinine (D/P Cr) ( P < 0.001) and TGF-ß1 ( P < 0.001) in human PD effluent. VEGF-A mRNA levels increased significantly in the peritoneal tissues of human ultrafiltration failure (UFF) patients and correlated with number of vessels ( P < 0.01) and peritoneal thickness ( P < 0.001). TGF-ß1 increased VEGF-A production in human mesothelial cell lines and fibroblast cell lines, and TGF-ß1-induced VEGF-A was suppressed by TGF-ß receptor I (TGFßR-I) inhibitor. Incremental peak values of VEGF-A mRNA stimulated by TGF-ß1 in human cultured mesothelial cells derived from PD patients with a range of peritoneal membrane functions correlated with D/P Cr ( P < 0.05). To evaluate the regulatory mechanisms of VEGF-A and neoangiogenesis in vivo, we administered TGFßR-I inhibitor intraperitoneally in a rat chlorhexidine-induced peritoneal injury (CG) model. TGFßR-I inhibitor administration in the CG model decreased peritoneal thickness ( P < 0.001), the number of vessels ( P < 0.001), and VEGF-A levels ( P < 0.05). These results suggest that neoangiogenesis is associated with fibrosis through the TGF-ß1-VEGF-A pathway in mesothelial cells and fibroblasts. These findings are important when considering the strategy for management of UFF in PD patients.

Apoptosis inhibitor of macrophage ameliorates fungus-induced peritoneal injury model in mice.

Fungal peritonitis in a patient on peritoneal dialysis (PD) is a refractory injury accompanied by severe inflammation, predisposing patients to a poor prognosis. Defective clearance of necrotic tissue interferes with amelioration of tissue injury and induces abnormal tissue remodeling. In the recent reports, apoptosis inhibitor of macrophage (AIM, also called CD5L) prevents obesity, hepatocellular carcinoma and acute kidney injury. Here, we investigated potential roles of AIM in prevention of progression of fungal peritonitis models. AIM -/- mice subjected to zymosan-induced peritonitis exhibited progressive inflammation and sustained peritoneal necrosis tissue on day 28 after the disease induction, whereas there was an improvement in AIM +/+ mice. This appeared to be caused by deposition of AIM at the necrotic peritoneum in AIM +/+ mice. In vitro, AIM enhanced the engulfment of necrotic debris by macrophages derived from zymosan-induced peritonitis, M1- and M2a-like bone marrow derived macrophages, as well as by mesothelial cells. In addition, administration of recombinant AIM dramatically ameliorated severe inflammation associated with necrosis in zymosan-induced peritonitis of AIM -/- mice. Our observations suggest that AIM appears to be involved in the repair process of zymosan-induced peritonitis, and thus, could be the basis of development of new therapeutic strategies for PD-related fungal peritonitis.

Sodium chloride promotes tissue inflammation via osmotic stimuli in subtotal-nephrectomized mice.

Chronic inflammation, which is often associated with high all-cause and cardiovascular mortality, is prevalent in patients with renal failure; however, the precise mechanisms remain unclear. High-salt intake was reported to induce lymphangiogenesis and autoimmune diseases via osmotic stimuli with accumulation of sodium or chloride. In addition, sodium was recently reported to be stored in the extremities of dialysis patients. We studied the effects and mechanisms of high salt loading on tissue and systemic inflammation in subtotal-nephrectomized mice (5/6Nx) and in cultured cells. Macrophage infiltration in the peritoneal wall (P<0.001), heart (P<0.05) and para-aortic tissues (P<0.001) was significantly higher in 5/6Nx with salt loading (5/6Nx/NaCl) than in 5/6Nx without salt loading (5/6Nx/Water); however, there were no significant differences in blood pressure and renal function between the groups. Tissue interleukin-6, monocyte chemotactic protein-1 (MCP-1), serum- and glucocorticoid-inducible kinase 1 (Sgk1) and tonicity-responsive enhancer binding protein (TonEBP) mRNA were significantly elevated in the peritoneal wall and heart with 5/6Nx/NaCl when compared with 5/6Nx/Water. Sodium was stored in the abdominal wall, exerting high-osmotic conditions. Reversal of salt loading reduced macrophage infiltration associated with decreased TonEBP in 5/6Nx/NaCl. Macrophage infiltration associated with fibrosis induced by salt loading was decreased in the 5/6Nx/NaCl/CC chemokine receptor 2 (CCR2, receptor of MCP-1)-deficient mice when compared with 5/6Nx/NaCl/Wild mice, suggesting that CCR2 is required for macrophage infiltration in 5/6Nx with NaCl loading. In cultured mesothelial cells and cardiomyocytes, culture media with high NaCl concentration induced MCP-1, Sgk1 and TonEBP mRNA, all of which were suppressed by TonEBP siRNA, indicating that both MCP-1 and Sgk1 are downstream of TonEBP. Our study indicates that high NaCl intake induces MCP-1 expression leading to macrophage infiltration via the TonEBP-MCP-1 pathway in 5/6Nx/NaCl mice, and that TonEBP has a central role in inflammation in patients with renal failure taking high salt.

High Levels of Soluble C5b-9 Complex in Dialysis Fluid May Predict Poor Prognosis in Peritonitis in Peritoneal Dialysis Patients.

BACKGROUND: We searched for indicators to predict the prognosis of infectious peritonitis by measuring levels of complement proteins and activation products in peritoneal dialysis (PD) fluid (PDF) of patients at early stages of peritonitis. We retrospectively analyzed the relationship between the levels of sC5b-9, C3 and C4 in PDF and the subsequent clinical prognosis. METHODS: We measured levels of sC5b-9, C3 and C4 in PDF on days 1, 2 and 5 post-onset of peritonitis in 104 episodes of infectious peritonitis in PD patients from 2008 and retrospectively compared levels with clinical outcomes. Further analysis for the presence of causative microorganisms or to demonstrate bacterial culture negative peritonitis was performed and correlated with change of levels of sC5b-9 in PDF. RESULTS: When PD patients with peritonitis were divided into groups that either failed to recover from peritonitis and were finally withdrawn from PD (group 1; n = 25) or recovered (group 2; n = 79), levels of sC5b-9, C3 and C4 in PDF were significantly higher in group 1 patients compared to those in group 2 on day5. Analysis of microorganisms showed significantly higher sC5b-9 levels in PDF of peritonitis cases caused by culture negative peritonitis in group 1 compared with group 2 when we analyzed for individual microorganisms. Of note, on day5, the sC5b-9 levels in PDF were similarly high in peritonitis caused by fungi or other organisms. CONCLUSION: Our results suggested that levels of complement markers in PDF, especially sC5b-9, have potential as surrogate markers to predict prognosis of PD-related peritonitis.

Vascular Endothelial Cell Injury Is an Important Factor in the Development of Encapsulating Peritoneal Sclerosis in Long-Term Peritoneal Dialysis Patients.

BACKGROUND AND OBJECTIVES: Encapsulating peritoneal sclerosis (EPS) is a rare but serious and life-threatening complication of peritoneal dialysis (PD). However, the precise pathogenesis remains unclear; in addition, predictors and early diagnostic biomarkers for EPS have not yet to be established. METHODS: Eighty-three peritoneal membrane samples taken at catheter removal were examined to identify pathological characteristics of chronic peritoneal deterioration, which promotes EPS in patients undergoing long-term PD treatment with low occurrence of peritonitis. RESULTS: According to univariable logistic regression analysis of the pathological findings, thickness of the peritoneal membrane (P = 0.045), new membrane formation score (P = 0.006), ratio of luminal diameter to vessel diameter (L/V ratio, P<0.001), presence of CD31-negative vessels (P = 0.021), fibrin deposition (P<0.001), and collagen volume fraction (P = 0.018) were associated with EPS development. In analyses of samples with and without EPS matched for PD treatment period, non-diabetes, and PD solution, univariable analysis identified L/V ratio (per 0.1 increase: odds ratio (OR) 0.44, P = 0.003) and fibrin deposition (OR 6.35, P = 0.027) as the factors associated with EPS. L/V ratio was lower in patients with fibrin exudation than in patients without fibrin exudation. CONCLUSIONS: These findings suggest that damage to vascular endothelial cells, as represented by low L/V ratio, could be a predictive finding for the development of EPS, particularly in long-term PD patients unaffected by peritonitis.

Recent analysis of status and outcomes of peritoneal dialysis in the Tokai area of Japan: the second report of the Tokai peritoneal dialysis registry.

BACKGROUND: Early withdrawal within 3 years after starting peritoneal dialysis (PD) and PD-related peritonitis have been major obstacles preventing increases in the population of PD patients. To address these problems, we implemented education programs for medical staff. This study analyzed the recent status and outcomes of PD therapy, focusing on findings such as the incidence and prognosis of peritonitis as of 5 years after our last study. METHODS: We investigated background, laboratory data and status of PD therapy, reasons for withdrawal from PD and incidental statements on peritonitis from 2010 to 2012 (R2), and compared findings with those from our last study of 2005-2007 (R1). RESULTS: Early PD therapy withdrawal in R2 clearly improved to 44.7 %, compared with 50.9 % in R1. Peritonitis incidence improved slightly from once per 42.8 months/patient in R1 to once per 47.3 months/patient in R2. Notably, PD-related peritonitis as a cause of mortality improved markedly in R2, but outcomes of PD-related peritonitis did not change significantly between R1 and R2. In contrast, social problems increased as a reason for withdrawal from PD therapy. CONCLUSION: Our efforts at education might have been useful for improving early withdrawal from PD and deaths attributable to PD-related peritonitis. However, since improvements to incidence of PD-related peritonitis were limited by education, further improvement in PD-related peritonitis incidence requires development of new sterilized connecting systems during PD-bag exchanges to decrease PD-related peritonitis opportunities. Construction of medical support systems to address social problems is required to maintain long-term PD therapy.

The efficacy of tolvaptan as a diuretic for chronic kidney disease patients.

BACKGROUND: Tolvaptan selectively binds to the vasopressin V2 receptor and inhibits reabsorption of free water. Although its efficacy for heart failure has been proven, its efficacy for chronic kidney disease (CKD) patients has not been assessed in detail. METHODS: We examined 20 CKD patients (13 men and 7 women) who presented with volume overload and who were administered tolvaptan. We assessed urine volume (UV) and blood biochemistry before administration (dO), 1 day after administration (d1), and 7 to 14 days after administration (d7-14). RESULTS: The mean age was 74.0 +/- 13.1 years. Besides CKD, there were 9, 8, and 5 patients with heart failure, liver failure or liver cirrhosis, andsevere oedema, respectively. UV significantly increased from 959.0 +/- 503.8 mL/day at d0 to 1605.4 +/- 964.0 mL/day at d7-14 (P<0.01). Serum creatinine levels were not exacerbated (3.89 +/- 3.43 mg/dL at d0 and 3.66 +/- 3.02 mg/dL at d7-14). Serum albumin (ALB) levels and urinary protein creatinine ratio (uPCR) did not correlate with UV change. Estimated glomerular filtration rate (eGFR) correlated with UV change from d0 to d1 (r=0.6619, P<0.01). Serum sodium elevation correlated with increased UV (r=0.4951, P<0.05). CONCLUSION: Tolvaptan is useful to reduce volume overload without exacerbation of the renal function; its effect does not depend on ALB or uPCR. the eGFR correlated with the efficacy of tolvaptan. If UV increases drastically after tolvaptan administration, serum Na levels should be carefully monitored.

Vascular endothelial growth factor receptor-3 is a novel target to improve net ultrafiltration in methylglyoxal-induced peritoneal injury.

Appropriate fluid balance is important for good clinical outcomes and survival in patients on peritoneal dialysis. We recently reported that lymphangiogenesis associated with fibrosis developed in the peritoneal cavity via the transforming growth factor-ß1-vascular endothelial growth factor-C (VEGF-C) pathway. We investigated whether VEGF receptor-3 (VEGFR-3), the receptor for VEGF-C and -D, might be a new target to improve net ultrafiltration by using adenovirus-expressing soluble VEGFR-3 (Adeno-sVEGFR-3) in rodent models of peritoneal injury induced by methylglyoxal (MGO). We demonstrated that lymphangiogenesis developed in these MGO models, especially in the diaphragm, indicating that lymphangiogenesis is a common feature in the peritoneal cavity with inflammation and fibrosis. In MGO models, VEGF-D was significantly increased in the diaphragm; however, VEGF-C was not significantly upregulated. Adeno-sVEGFR-3, which was detected on day 50 after administration via tail vein injections, successfully suppressed lymphangiogenesis in the diaphragm and parietal peritoneum in mouse MGO models without significant effects on fibrosis, inflammation, or neoangiogenesis. Drained volume in the peritoneal equilibration test using a 7.5% icodextrin peritoneal dialysis solution (the 7.5% icodextrin peritoneal equilibration test) was improved by Adeno-sVEGFR-3 on day 22 (P<0.05) and day 50 after reduction of inflammation (P<0.01), indicating that the 7.5% icodextrin peritoneal equilibration test identifies changes in lymphangiogenesis. The solute transport rate was not affected by suppression of lymphangiogenesis. In human peritoneal dialysis patients, the dialysate to plasma ratio of creatinine positively correlated with the dialysate VEGF-D concentration (P<0.001). VEGF-D mRNA was significantly higher in the peritoneal membranes of patients with ultrafiltration failure, indicating that VEGF-D is involved in the development of lymphangiogenesis in peritoneal dialysis patients. These results indicate that VEGFR-3 is a new target to improve net ultrafiltration by suppressing lymphatic absorption and that the 7.5% icodextrin peritoneal equilibration test is useful for estimation of lymphatic absorption.

Expression of membrane complement regulators, CD46, CD55 and CD59, in mesothelial cells of patients on peritoneal dialysis therapy.

We investigated the expression of membrane complement regulators (CRegs), CD46, CD55 and CD59 in human mesothelial cells, and correlated with clinical background and level of complement (C) activation products in peritoneal dialysis (PD) fluids (PDF) to clarify influence of the C activation system in PD patients. Expression of CRegs was assessed on primary cultures of mesothelial cells (HPMC) harvested from PD fluid of 31 PD patients. Because expression of CD55 but not CD46 and CD59 in mesothelial cells was significantly correlated to value of dialysate-to-plasma creatinine concentration ratio (D/P Cre) (p<0.005) as an indicator of peritoneal function, we focused on analysis of CD55 expression of HPMCs in comparison with levels of C activation products in the PDF of the PD patients, and their background factors. When comparing expression of the CRegs between systemic neutrophils and HPMC, no correlation was observed, supporting that change of CRegs' expression in HPMC was independently occurring in the peritoneum. Expression of CD55 protein in HPMC was closely correlated with expression at the mRNA level (p<0.0001) and was inversely correlated with levels of sC5b-9 (p<0.05), but not C3, C4, IL6 and CA125 in the PDF. Complications of diabetes, usage of icodextrin and residual renal function were not correlated with change of CD55 expression in HPMCs. Our data show that the process of PD therapy modifies expression of CD55 on peritoneal mesothelium and triggers local C activation. These findings support efforts to modify PD therapy to limit effects on activation and regulation of the C system.

Calcified amorphous tumor in the left atrium in a patient on long-term peritoneal dialysis.

A 66-year-old woman with an 11-year history of peritoneal dialysis (PD) for diabetic nephropathy and renal failure exhibited a movable tumor in the left atrium on echocardiography. Tumor resection was performed due to the difficulty in diagnosing the tumor and the future risk of heart failure and embolization. Light microscopy showed a calcified amorphous tumor (CAT), a rare intracardiac mass characterized by the presence of a pedicle and diffuse calcification. An increased calcium-phosphate product level was suspected as an etiology, although degeneration, inflammation and/or mineral balance disorders may also induce the development of CAT. We herein report the first known case of CAT in a PD patient.