Blood Pressure Control and Left Ventricular Hypertrophy in Long-Term Capd and Hemodialysis Patients: A Cross-Sectional Study

Background

It is still not clear whether hypertension and left ventricular hypertrophy (LVH) are more common in continuous ambulatory peritoneal dialysis (CAPD) than in hemodialysis (HD) patients.

Methods

To examine this subject, the indices of cardiac performance were compared between 50 HD and 34 CAPD patients. Patients were further divided into two subgroups [long-term (L) CAPD and L-HD] according to dialysis modality and duration of dialysis (more than 60 months’ duration).

Results

The blood pressure and cardiothoracic index of CAPD patients did not differ from HD patients. On average, the left atrial index was 2 mm/m2higher in HD patients than in CAPD patients. Left ventricular chamber sizes, wall thickness, and left ventricular mass index (LVMI) in patients on CAPD were similar to those of HD patients. Isovolumic relaxation time (IVRT) of CAPD patients was insignificantly less than that of HD patients (101 ± 22 and 115 ± 27 msec respectively). There was no significant difference between the two subgroups (L-HD and L-CAPD) in blood pressure, left atrial diameter, left ventricular chamber size, wall thickness, LVMI, ejection fraction, or IVRT.

Conclusion

If normovolemia and normotension are obtained by strict volume control without using antihypertensive drugs, the effects of the two modalities of chronic dialysis treatment (HD and CAPD) on cardiac structure and function are not different from each other.

Atorvastatin Improves Peritoneal Sclerosis Induced by Hypertonic PD Solution in Rats

Background

Peritoneal sclerosis is a complication of peritoneal dialysis and results in ultrafiltration failure. It is related to chronic peritoneal injury due to dialysis solution content and recurrent peritonitis. Statins have anti-inflammatory properties which may be of value in modulating responses to injury. We evaluated the capacity of atorvastatin to modify peritoneal alterations secondary to hypertonic glucose.

Methods

Thirty-two non-uremic rats were divided into three groups: group I (Sham) rats received no treatment (n=11), group II received hypertonic (3.86%, 10 ml/day) PD solution (n=10) and group III received hypertonic PD solution (10 ml/day) plus 80 mg/L atorvastatin in drinking water (n=11). After four weeks, a one-hour peritoneal equilibration test (PET) was performed with 3.86% PD solution. Dialysate-to-plasma urea ratio (D/P urea), glucose reabsorption (D1/D0 glucose), ultrafiltration volume (UF), dialysate protein, TGF-ß1 and VEGF levels were determined.

Results

Administration of atorvastatin resulted in preserved UF (4.9±0.8 vs 7.5±0.6 mL, p <0.01), protein loss (2.2±0.2 vs 2.1±0.1 g/L, p >0.05), and peritoneal thickness (53±3 vs 26±4 μm, p <0.01). D1/D0 glucose was significantly reduced in the dextrose group (0.70±0.02 vs 0.56±0.04, p <0.01). Both higher levels of TGF-ß1 (206±40 vs 474±120 pg/mL, p<0.05), and VEGF in dialysate effluent (4±0.4 vs 7.9±3 pg/mL, p>0.05), was determined in the dextrose group.

Conclusion

Exposure to hypertonic glucose solution resulted in alterations in peritoneal transport manifested by a rapid dissipation of the glucose gradient and resultant impaired UF response. Administration of atorvastatin led to prevention of these alterations. We suggest that the anti-inflammatory properties of statins are useful in providing protection of the peritoneal membrane from the effects of hypertonic glucose.

Pharmacologic targets and peritoneal membrane remodeling

Peritoneal dialysis (PD) is associated with functional and structural changes of the peritoneal membrane, also known as peritoneal remodeling. The peritoneal membrane is affected by many endogenous and exogenous factors such as cytokines, PD fluids, and therapeutic interventions. Here, we present an overview of various studies that have investigated pharmacologic interventions aimed at regression of peritoneal damage and prolongation of PD treatment.

Connective tissue growth factor knockdown attenuated matrix protein production and vascular endothelial growth factor expression induced by transforming growth factor-beta1 in cultured human peritoneal mesothelial cells

Connective tissue growth factor (CTGF), a downstream mediator of transforming growth factor-beta1 (TGF-beta1) inducing fibrosis, has recently been implicated in peritoneal fibrosis. Extracellular matrix (ECM) accumulation and angiogenesis are characteristic changes in peritoneal fibrosis. In this study we investigated the effect of CTGF knockdown via interference RNA (RNAi) on ECM production and vascular endothelial growth factor (VEGF) expression induced by TGF-beta1 in human peritoneal mesothelial cells (HPMCs). Four CTGF short hairpin RNA (shRNA) expression constructs were generated using the pRetroSuper vector, and infectious retroviral particles were prepared to infect HPMCs. Expression levels of CTGF, fibronectin(FN), collagen 1 (col 1), laminin, and VEGF mRNA and protein were measured by semi-quantitative reverse transcription polymerase chain reaction and western blot assay. CTGF expression was increased after stimulation with TGF-beta1, but inhibited using each of the four independent CTGF shRNA constructs (P < 0.01). Moreover, expression of ECM proteins (FN, col 1, and laminin) and VEGF were upregulated after incubation with TGF-beta1, but elevated levels of ECM and VEGF induced by TGF-beta1 were significantly inhibited by RNAi (P < 0.01), but not by the empty retroviral vector (P > 0.05). From these results, we concluded that retrovirus-mediated CTGF shRNA can effectively inhibit ECM production and VEGF expression induced by TGF-beta1 in HPMCs. This study suggests that downregulation of CTGF may represent a potential therapeutic approach for peritoneal fibrosis through decreasing ECM accumulation and angiogenesis.

Smad7 transgene attenuates peritoneal fibrosis in uremic rats treated with peritoneal dialysis

Transforming growth factor beta (TGF-beta) plays a critical role in the pathogenesis of the peritoneal fibrosis that complicates long-term peritoneal dialysis (PD). We studied the TGF-beta/Smad signaling pathway in peritoneal fibrosis induced in uremic rats treated with PD and explored the therapeutic potential of Smad7 to prevent fibrogenesis. After subtotal nephrectomy, uremic rats were treated with peritoneal dialysis using 4.25% dextrose-containing fluid. The peritoneum of uremic rats treated with PD demonstrated fibrosis, increased TGF-beta expression, increased Smad2/3 activation, decreased Smad7 expression, and increased expression of fibrogenic and angiogenic factors. In addition, peritoneal function was impaired and its structure was altered, including a thickened submesothelial layer. In rats transfected with a Smad7 transgene using an ultrasound-microbubble-mediated system, peritoneal fibrosis was attenuated, peritoneal function was improved, and Smad2/3 activation was inhibited. We suggest that administration of Smad7 inhibits peritoneal fibrogenesis in uremic rats treated with PD by correcting the imbalance between downregulated Smad7 and activated Smad2/3. Blockade of the TGF-beta/Smad signaling pathway may represent a novel therapeutic approach to prevent peritoneal fibrosis in patients treated with PD.

Restoration of peritoneal integrity after withdrawal of peritoneal dialysis: characteristic features of the patients at risk of encapsulating peritoneal sclerosis

BACKGROUND

The epidemiological characteristics of encapsulating peritoneal sclerosis (EPS), such as its high incidence in patients with long-term peritoneal dialysis (PD) treatment, and the onset of EPS after patients are switched to hemodialysis (HD) may indicate an activated pathological process after PD withdrawal, especially in long-term PD patients. Accordingly, we aimed to observe changes in peritoneal function after the stoppage of PD, and to clarify the characteristic features of the patients at risk of EPS.

METHODS

Thirty-three patients who were switched from continuous ambulatory peritoneal dialysis (CAPD) to HD were enrolled in this trial. Changes in the dialysate/plasma creatinine (D/P Cr) and CA125 levels in the effluent of the peritoneal equilibration test were observed for 6 months. Furthermore, each patient was followed-up for 36 months after PD withdrawal to monitor for the development of EPS.

RESULTS

D/P Cr decreased significantly, while CA125 levels tended to increase. Nine patients developed EPS during the follow-up period and they specifically showed significant increases of D/P Cr levels and significantly lower levels of CA125 at PD withdrawal. The accumulation of high transporters in the EPS group at 0 and 6 months after PD withdrawal was significant.

CONCLUSIONS

Peritoneal recovery may take place after withdrawal from PD treatment and such recover indicated by improvement of transport states and a rise of the CA125 level. The present study revealed that a high-transport state and lack of increase of CA125 in the effluent were associated with EPS development after PD withdrawal. This may suggest that the lack of peritoneal recovery after PD withdrawal is predictive for EPS development.

Octreotide therapy for chylous ascites in a chronic dialysis patient

Chylous ascites, a rare complication in patients receiving continuous peritoneal dialysis, often presents with turbid dialysate. This characteristic makes it frequently confused with peritonitis. Conservative treatments including bowel rest and dietary intervention with medium chain triglycerides are advised by many authors in the literature. However, this approach usually takes a long time before the lymphorrhagia are eventually resolved. Here, a case of chylous ascites that was successfully treated with subcutaneous octreotide, a somatostatin analogue, is reported. By shortening the bowel rest period, this treatment avoids the nutritional and immunological adverse effects. A series of peritoneal equilibrium tests were performed after administration of octreotide and the results showed that octreotide did not alter the peritoneal function in the short term. Therefore, subcutaneous octreotide administration is a safe and effective therapy in peritoneal dialysis patient with chylous ascites.

Genetic polymorphism of VEGF: Impact on longitudinal change of peritoneal transport and survival of peritoneal dialysis patients

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a pivotal role in the peritoneal angiogenesis and hyperpermeability in patients on peritoneal dialysis. We hypothesis that VEGF genetic polymorphism may affect the longitudinal change of peritoneal transport and clinical outcome of peritoneal dialysis patients.

METHODS

We studied 135 consecutive new peritoneal dialysis patients. VEGF genetic polymorphism at -1154 and -2578 positions were determined by polymerase chain reaction (PCR) methodologies. Standard peritoneal test and dialysis adequacy and transport test (DATT) were performed at the initiation of peritoneal dialysis. After 12 months, DATT was repeated in 83 patients. In 35 patients, VEGF production in vivo was determined by its levels in serum and peritoneal dialysis effluent, and mRNA expression in peritoneal dialysis effluent. Patients were followed for 19.4 +/- 8.5 months for survival study.

RESULTS

There was no relation between VEGF genotype and baseline peritoneal transport group. The changes in 24-hour dialysate-to-plasma (D/P) creatinine after 12 months were 0.028 +/- 0.159, -0.013 +/- 0.137, and 0.141 +/- 0.231 for CC, CA, and AA genotype at -2578 position, respectively [one-way analysis of variance (ANOVA), P= 0.028]. The AA genotype had significantly higher increase in 24-hour D/P creatinine than the other genotypes. Similar results were found with the genotype at -1154 position, which had marked linkage disequilibrium with the genotype at -2578 position. Actuarial patient survival was 90.3% and 74.9% at 24 months for CC and CA/AA genotypes at -2578 position, respectively (P= 0.036). After correcting for confounding covariates, the adjusted hazard ratio of death was 3.04 (95% CI, 1.10 to 8.36) for the CA/AA group as compared to CC group. Although baseline serum VEGF level was higher in patients with CC genotype than those with CA/AA genotype at -2578 position (541.5 +/- 322.8 pg/mL vs. 298.8 +/- 209.4 pg/mL, P= 0.012), VEGF mRNA expression in peritoneal dialysis effluent was significantly lower in patients with CC genotype (1.82 +/- 2.77 vs 4.48 +/- 3.28, P= 0.021). VEGF protein level in peritoneal dialysis effluent was also marginally lower in patients with CC genotype, although the difference was not significant. Genotype at -1154 position was not associated with VEGF production in vivo or patient survival.

CONCLUSION

We conclude that in peritoneal dialysis patients, the AA genotype of VEGF promoter at -2578 position was associated with progressive increase in peritoneal transport. The CA/AA genotype at -2578 position was also associated with an excess mortality. Our finding also suggests that systemic and local peritoneal VEGF production may be differentially regulated.