Bioincompatible impact of different peritoneal dialysis fluid components and therapeutic interventions as tested in a rat peritoneal dialysis model

Sterile inflammation of peritoneal membrane caused by peritoneal dialysis: focus on the communication between immune cells and peritoneal stroma

Peritoneal dialysis is a widely used method for treating kidney failure. However, over time, the peritoneal structure and function can deteriorate, leading to the failure of this therapy. This deterioration is primarily caused by infectious and sterile inflammation. Sterile inflammation, which is inflammation without infection, is particularly concerning as it can be subtle and often goes unnoticed. The onset of sterile inflammation involves various pathological processes. Peritoneal cells detect signals that promote inflammation and release substances that attract immune cells from the bloodstream. These immune cells contribute to the initiation and escalation of the inflammatory response. The existing literature extensively covers the involvement of different cell types in the sterile inflammation, including mesothelial cells, fibroblasts, endothelial cells, and adipocytes, as well as immune cells such as macrophages, lymphocytes, and mast cells. These cells work together to promote the occurrence and progression of sterile inflammation, although the exact mechanisms are not fully understood. This review aims to provide a comprehensive overview of the signals from both stromal cells and components of immune system, as well as the reciprocal interactions between cellular components, during the initiation of sterile inflammation. By understanding the cellular and molecular mechanisms underlying sterile inflammation, we may potentially develop therapeutic interventions to counteract peritoneal membrane damage and restore normal function.

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.

Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis

Peritoneal dialysis (PD) is a renal replacement therapy consistent on the administration and posterior recovery of a hyperosmotic fluid in the peritoneal cavity to drain water and toxic metabolites that functionally-insufficient kidneys are not able to eliminate. Unfortunately, this procedure deteriorates the peritoneum. Tissue damage triggers the onset of inflammation to heal the injury. If the injury persists and inflammation becomes chronic, it may lead to fibrosis, which is a common occurrence in many diseases. In PD, chronic inflammation and fibrosis, along with other specific processes related to these ones, lead to ultrafiltration capacity deterioration, which means the failure and subsequent cessation of the technique. Working with human samples provides information about this deterioration but presents technical and ethical limitations to obtain biopsies. Animal models are essential to study this deterioration since they overcome these shortcomings. A chronic mouse infusion model was developed in 2008, which benefits from the wide range of genetically modified mice, opening up the possibility of studying the mechanisms involved. This model employs a customized device designed for mice, consisting of a catheter attached to an access port that is placed subcutaneously at the back of the animal. This procedure avoids continuous puncture of the peritoneum during long-term experiments, reducing infections and inflammation due to injections. Thanks to this model, peritoneal damage induced by chronic PD fluid exposure has been characterized and modulated. This technique allows the infusion of large volumes of fluids and could be used for the study of other diseases in which inoculation of drugs or other substances over extended periods of time is necessary. This article shows the method for the surgical placement of the catheter in mice. Moreover, it explains the procedure for a 5/6 nephrectomy to mimic the state of renal insufficiency present in PD patients.