Diabetes influences peritoneal morphology in uremic patients at the initiation of peritoneal dialysis

Development and validation of prediction model for technique failure in peritoneal dialysis patients: An observational study

AIM

This study aimed to establish a prediction model in peritoneal dialysis patients to estimate the risk of technique failure and guide clinical practice.

METHODS

Clinical and laboratory data of 424 adult peritoneal dialysis patients were retrospectively collected. The risk prediction models were built using univariate Cox regression, best subsets approach and LASSO Cox regression. Final nomogram was constructed based on the best model selected by the area under the curve.

RESULTS

After comparing three models, the nomogram was built using the LASSO Cox regression model. This model included variables consisting of hypertension and peritonitis, serum creatinine, low-density lipoprotein, fibrinogen and thrombin time, and low red blood cell count, serum albumin, triglyceride and prothrombin activity. The predictive model constructed performed well using receiver operating characteristic curve and area under the curve value, C-index and calibration curve.

CONCLUSION

This study developed and verified a new prediction instrument for the risk of technique failure among peritoneal dialysis patients.

Alpha-klotho and peritoneal membrane status: A hypothesis generating study

BACKGROUND

Long-term success of peritoneal dialysis relies on the integrity of the peritoneal membrane. This proof-of-concept study addressed the hypothesis that fibrosis is already present in the membrane at pre-dialysis and that the membrane status is related to the individual's uraemic fingerprint.

METHODS

A clinical-mechanistic, transversal, single-centre study was conducted. Pre-dialysis peritoneal biopsies were scored considering the submesothelial compact zone thickness (STM), vasculopathy and inflammation. We investigated if the membrane status could be inferred from a panel of proteins (α-Klotho, Galectin-3, FGF21, FGF23, Tweak, TNFα and hsPCR) in blood.

RESULTS

A total 58 incident patients aged 56 ± 15 years old were included, 31% female, 55% hypertension, 29% diabetic and 24% obese. Person-to-person STM was found to be highly variable and 38% of patients were fibrosis positive. Both α-Klotho (Spearman r = -.7491, p < 0.001) and FGF21 (Spearman r = -.5102, p < 0.001) were negatively associated with STM. α-Klotho, but not FGF21, was able to discriminate fibrosis from nonfibrosis with/without inflammation and vasculopathy. PLS models identified α-Klotho as the protein most relevant for fibrosis. α-Klotho was independently associated with fibrosis of the peritoneal membrane (OR = .991 (.896-.997), p = 0.002).

CONCLUSION

Before the start of dialysis in incident patients, some patients already present fibrosis of the peritoneal membrane and other patients do not. Our findings suggest that α-Klotho may be implicated in fibrosis of the peritoneal membrane.

Advanced glycation end products are associated with immature angiogenesis and peritoneal dysfunction in patients on peritoneal dialysis

BACKGROUND

Deposition of advanced glycation end products (AGEs) is frequently found in the peritoneum of patients on peritoneal dialysis (PD). Angiogenesis is also observed in the peritoneum. However, the clinical significance of AGEs and angiogenesis in the peritoneum is not fully understood. We evaluated the maturation of capillary vessels and investigated whether AGEs are associated with angiogenesis and peritoneal function in the peritoneal membrane.

METHODS

Peritoneum obtained when PD catheters were removed from 61 patients with PD was analyzed. The peritoneum was immunohistochemically stained with anti-CD34 (for endothelial cells), anti-alpha smooth muscle actin (αSMA) (for pericytes), and anti-AGE antibodies. We defined CD34-positive and αSMA-negative vessels as immature capillary vessels in peritoneal membranes using serial sections. We evaluated the associations between vessel density, peritoneal function (dialysate-to-plasma ratio for creatinine (D/P creatinine)), and the degree of AGE deposition.

RESULTS

AGE accumulation in the interstitium was positively associated with the duration of PD (p < 0.01). AGE accumulation in the interstitium and vascular wall was positively correlated with the use of acidic solution (p < 0.05) and the maximum value of D/P creatinine (p < 0.05). AGE accumulation in the vascular wall was significantly associated with immature capillary density (CD34+/αSMA-) in the peritoneum (p < 0.01). Vessel density was not significantly correlated with the last measurement of D/P creatinine (p = 0.126, r = 0.202), However, immature capillary density was positively correlated with the last measurement of D/P creatinine (p < 0.05, r = 0.278).

CONCLUSIONS

AGE accumulation is significantly associated with immature angiogenesis and peritoneal dysfunction in patients undergoing PD.

Proposal of peritoneal biopsy procedures for patients undergoing peritoneal dialysis

Prolonged peritoneal dialysis (PD) is responsible for progressive morphological changes such as deterioration of the peritoneal membrane. These changes increase the risk of encapsulating peritoneal sclerosis (EPS). Histological assessments of peritoneal membrane biopsy samples are fundamental for the evaluation of the peritoneal damage caused by PD. For evaluating serial morphological changes induced in the peritoneum by PD, we recommend to perform peritoneal biopsy examinations not only after the cessation of PD but also before performing PD. At the time of PD catheter insertion, the parietal peritoneum (1.5 × 1.5 cm) and rectus abdominal muscle posterior sheath is sampled at a point 3 cm below the PD catheter insertion site. Furthermore, at the time of PD catheter removal, the parietal peritoneum is sampled at a point 3 cm apart from the PD catheter insertion site to avoid artifacts. The peritoneum should be evaluated to detect mesothelial cell denudation, acellular sclerotic changes and thickness of the submesothelial connective tissue, vasculopathy of the post-capillary venules, vascular angiogenesis, and new encapsulating membrane. The method presented herein allows the minimization of surgical invasiveness and artifacts of the specimens and safe performance of peritoneal biopsy examinations. Morphological evaluation of the peritoneum involving an appropriate biopsy strategy, in conjunction with functional markers of deterioration, such as peritoneal permeability or cytokine levels, is a useful approach for examining peritoneal damage and predicting the prognosis of PD patients, especially the onset of EPS.

Peritoneal Membrane Preservation

Peritoneal dialysis (PD) is a successfully used method for renal replacement therapy. However, long-term PD may be associated with peritoneal fibrosis and ultrafiltration failure. The key factors linked to their appearance are repeated episodes of inflammation associated with peritonitis and long-term exposure to bioincompatible PD fluids. Different strategies have been proposed to preserve the peritoneal membrane. This article reviews the functional and structural alterations related to PD and strategies whereby we may prevent them to preserve the peritoneal membrane. The use of new, more biocompatible, PD solutions is promising, although further morphologic studies in patients using these solutions are needed. Blockade of the renin-angiotensin-aldosterone system appears to be efficacious and strongly should be considered. Other agents have been proven in experimental studies, but most of them have not yet been tested appropriately in human beings.

Peritoneal Water Transport Characteristics of Diabetic Patients Undergoing Peritoneal Dialysis: A Longitudinal Study

BACKGROUND

Volume overload is frequent in diabetics undergoing peritoneal dialysis (PD), and may play a significant role in the excess mortality observed in these patients. The characteristics of peritoneal water transport in this population have not been studied sufficiently.

METHOD

Following a prospective, single-center design we made cross-sectional and longitudinal comparisons of peritoneal water transport in 2 relatively large samples of diabetic and nondiabetic PD patients. We used 3.86/4.25% glucose-based peritoneal equilibration tests (PET) with complete drainage at 60 min, for these purposes.

MAIN RESULTS

We scrutinized 59 diabetic and 120 nondiabetic PD patients. Both samples showed relatively similar characteristics, although diabetics were significantly more overhydrated than nondiabetics. The baseline PET disclosed lower ultrafiltration (mean 439 mL diabetics vs. 532 mL nondiabetics, p = 0.033) and sodium removal (41 vs. 53 mM, p = 0.014) rates in diabetics. One hundred and nine patients (36 diabetics) underwent a second PET after 12 months, and 45 (14 diabetics) underwent a third one after 24 months. Longitudinal analyses disclosed an essential stability of water transport in both groups, although nondiabetic patients showed a trend where an increase in free water transport (p = 0.033) was observed, which was not the case in diabetics.

CONCLUSIONS

Diabetic patients undergoing PD present lower capacities of ultrafiltration and sodium removal than their nondiabetic counterparts. Longitudinal analyses disclose an essential stability of water transport capacities, both in diabetics and nondiabetics. The clinical significance of these differences deserves further analysis.