Multidisciplinary clinical strategies for encapsulating peritoneal sclerosis in peritoneal dialysis: update from Japan

Risk Factors for Early Peritoneal Dialysis Discontinuation: Importance of Heart Failure

BACKGROUND

The number of patients on peritoneal dialysis (PD) in our hospital has increased during the past 5 years, but the number discontinuing PD has also increased. The purpose of this study was to identify the risk factors for PD discontinuation by analyzing the association between technical survival period (defined as the duration of PD) and various clinical factors.

METHODS

We retrospectively investigated 87 patients who were started on PD at our hospital and attended regularly from April 2015 to March 2020, and we analyzed the association between technical survival period and various clinical factors. We also looked for associations between technical survival period and hospitalizations for heart failure, peritonitis, and exit-site infections among patients undergoing PD.

RESULTS

The patients using renin-angiotensin-aldosterone system inhibitors (RASi) (P = 0.0218), those with left ventricular ejection fraction (LVEF) > 50% (P = 0.0194) when they started PD, and those with estimated glomerular filtration rate (eGFR) ≥ 6 (mL/ min/1.73m²) (P = 0.0013) at the initiation of PD showed significantly longer technical survival period, and those who were hospitalized for heart failure had significantly shorter period (P = 0.0008).

CONCLUSION

Treatment of RASi, LVEF > 50% and eGFR ≥ 6 mL/ min/1.73m² when the initiation of PD and better volume control to prevent ultrafiltration failure and heart failure may improve technical survival period in patients undergoing PD.

Recent Understanding of Peritoneal Pathology in Peritoneal Dialysis Patients in Japan

The thin peritoneum covering the peritoneal cavity has been used as a dialysis membrane for peritoneal dialysis (PD) because it is highly vascularized and has a large body surface area. However, it has been reported that peritoneal membranes affected by peritonitis, as well as those exposed to the nonphysiological high glucose levels containing PD dialysate, may undergo histological and functional changes. Patients undergoing PD may experience encapsulating peritoneal sclerosis (EPS), which is a life-threatening serious complication of PD that can significantly impair activities of daily living. The incidence of EPS was 1.4-7.3% of maintenance PD patients in the 1980s. The incidence has improved to 1.0% after a neutral dialysate became the standard PD treatment in Japan. Furthermore, the pathogenesis of EPS is uncertain although its onset may be explained by the "two-hit theory," in which some factors leading to impairment had an additive effect on simple peritoneal sclerosis. The evaluation of histopathological findings has shown the impact of the neutral dialysate on peritoneal deterioration as well as its role in the development of functional changes. In the present report, we discuss the advances in the understanding of peritoneal deterioration based on histological and macroscopic evaluations of the peritoneum of patients undergoing PD. We also discuss the recent treatment for PD patients.

Delayed administration of suramin attenuates peritoneal fibrosis in rats

BACKGROUND

Peritoneal fibrosis is the most common complication of peritoneal dialysis, but there is currently no effective treatment. We previously reported that suramin pretreatment prevents the development of peritoneal fibrosis in a rat model of peritoneal fibrosis induced by chlorhexidine gluconate (CG). Here, we further examined the effectiveness of delayed administration of suramin on peritoneal fibrosis and the mechanism (s) involved in this process.

METHODS

In the rat model of peritoneal fibrosis induced by CG, suramin or saline was administered at day 21 and 28. All rats were then sacrificed to collect peritoneal tissues for Western blot analysis and histological staining at day 35.

RESULTS

Our results demonstrated that delayed administration of suramin starting at 21 days following CG injection can ameliorate peritoneal damage, with greater efficacy after two injections. Suramin also reduced the expression of α-smooth muscle actin, Collagen 1, and Fibronectin and suppressed phosphorylation of Smad-3, epidermal growth factor receptor (EGFR), signal transducers, activator of transcription 3 (STAT3) as well as extracellular signal-regulated kinases 1/2 (ERK 1/2) in the peritoneum injured with CG. Moreover, delayed administration of suramin inhibited overproduction of transforming growth factor-β1(TGF-β1) and expression of several pro-inflammatory cytokines, including monocyte chemoattractant protein-1, tumor necrosis factor-α, interleukin-1, and interleukin-6.

CONCLUSIONS

Our results indicated that suramin can attenuate progression of peritoneal fibrosis by a mechanism involving inhibition of the TGF-β1/Smad3 and EGFR signaling pathways as well as suppression of multiple proinflammatory cytokines. Thus, suramin may have the potential to offer an effective treatment for peritoneal fibrosis.

Dissolved molecular hydrogen (H2) in Peritoneal Dialysis (PD) solutions preserves mesothelial cells and peritoneal membrane integrity

Background

Peritoneal dialysis (PD) is used as renal replacement therapy in patients with end-stage kidney disease. However, peritoneal membrane failure remains problematic and constitutes a critical cause of PD discontinuation. Recent studies have revealed the unique biological action of molecular hydrogen (H₂) as an anti-oxidant, which ameliorates tissue injury. In the present study, we aimed to examine the effects of H₂ on the peritoneal membrane of experimental PD rats.

Method

Eight-week-old male Sprague-Dawley rats were divided into the following groups (n = 8–11 each) receiving different test solutions: control group (no treatment), PD group (commercially available lactate-based neutral 2.5% glucose PD solution), and H₂PD group (PD solution with dissolved H₂ at 400 ppb). Furthermore, the influence of iron (FeCl₃: 5 μM: inducer of oxidative cellular injury) in the respective PD solutions was also examined (Fe-PD and Fe-H₂PD groups). The H₂PD solution was manufactured by bathing a PD bag in H₂-oversaturated water created by electrolysis of the water. Twenty mL of the test solutions were intraperitoneally injected once a day for 10 days. Parietal peritoneum samples and cells collected from the peritoneal surface following treatment with trypsin were subjected to analysis.

Results

In the PD group as compared to controls, a mild but significant sub-mesothelial thickening was observed, with increase in the number of cells in the peritoneal surface tissue that were positive for apoptosis, proliferation and vimentin, as seen by immunostaining. There were significantly fewer of such changes in the H₂PD group, in which there was a dominant presence of M2 (CD163+) macrophages in the peritoneum. The Fe-PD group showed a significant loss of mesothelial cells with sub-mesothelial thickening, these changes being ameliorated in the Fe-H₂PD group.

Conclusion

H₂-dissolved PD solutions could preserve mesothelial cells and peritoneal membrane integrity in PD rats. Clinical application of H₂ in PD could be a novel strategy for protection of peritoneal tissue during PD treatment.

Recommendations for pathological diagnosis on biopsy samples from peritoneal dialysis patients

Peritoneal dialysis (PD) has been established as an essential renal replacement therapy for patients with end stage renal disease during the past half century. Histological evaluation of the peritoneal membrane has contributed to the pathophysiological understanding of PD-related peritoneal injury such as peritonitis, fibrosis, and encapsulating peritoneal sclerosis (EPS). Hyalinizing peritoneal sclerosis (HPS), also known as simple sclerosis, is observed in almost all of PD patients. HPS is morphologically characterized by fibrosis of the submesothelial interstitium and hyalinizing vascular wall, particularly of the post-capillary venule (PCV). Two histological factors, the thickness of submesothelial compact zone (SMC) and the lumen/vessel ratio (L/V) at the PCV, have been used for the quantitative evaluation of HPS. The measuring system on SMC thickness and L/V ratio is easy and useful for evaluating the severity of HPS. On the other hand, EPS is characterized by unique encapsulation of the intestines by an "encapsulating membrane". This newly formed membranous structure covers the visceral peritoneum of the intestines, which contains fibrin deposition, angiogenesis, and proliferation of fibroblast-like cells and other inflammatory cells. This review will cover the common understandings of PD-related peritoneal alterations and provide a basic platform for clinical applications and future studies in this field.