Paracrine effects of transplanted mesothelial cells isolated from temperature-sensitive SV40 large T-antigen gene transgenic rats during peritoneal repair

WeChat-Based Comprehensive Education on Egg White Protein Intake for Patients Undergoing Peritoneal Dialysis: A Combined Prospective and Retrospective Study

Protein malnutrition is a well-described complication of peritoneal dialysis (PD), a standard mode of treatment for end-stage renal disease (ESRD), and contributes to morbidity, treatment failure, and mortality. To assess the usefulness of WeChat-based education for ensuring optimal protein intake through the consumption of egg white protein, 140 young and middle-aged patients undergoing PD are assigned to either the intervention group or the control group. The results show that reinforcing comprehensive PD education using WeChat can improve nutritional parameters, clinical parameters, and quality of life.

Empagliflozin, a sodium glucose cotransporter-2 inhibitor, ameliorates peritoneal fibrosis via suppressing TGF-β/Smad signaling

Sodium glucose cotransporter-2 (SGLT-2) inhibitor has been reported to exert a glucose-lowering effect in the peritoneum exposed to peritoneal dialysis solution. However, whether SGLT-2 inhibitors can regulate peritoneal fibrosis by suppressing TGF-β/Smad signaling is unclear. We aimed to (i) examine the effect of the SGLT-2 inhibitor empagliflozin in reducing inflammatory reaction and preventing peritoneal dialysis solution-induced peritoneal fibrosis and (ii) elucidate the underlying mechanisms. High-glucose peritoneal dialysis solution or transforming growth factor β1 (TGF-β1) was used to induce peritoneal fibrosis in vivo, in a mouse peritoneal dialysis model (C57BL/6 mice) and in human peritoneal mesothelial cells in vitro, to stimulate extracellular matrix accumulation. The effects of empagliflozin and adeno-associated virus-RNAi, which is used to suppress SGLT-2 activity, on peritoneal fibrosis and extracellular matrix were evaluated. The mice that received chronic peritoneal dialysis solution infusions showed typical features of peritoneal fibrosis, including markedly increased peritoneal thickness, excessive matrix deposition, increased peritoneal permeability, and upregulated α-smooth muscle actin and collagen I expression. Empagliflozin treatment or downregulation of SGLT-2 expression significantly ameliorated these pathological changes. Inflammatory cytokines (TNF-α, IL-1β, IL-6) and TGF-β/Smad signaling-associated proteins, such as TGF-β1 and phosphorylated Smad (p-Smad3), decreased in the empagliflozin-treated and SGLT-2 downregulated groups. In addition, empagliflozin treatment and downregulation of SGLT-2 expression reduced the levels of inflammatory cytokines (TNF-α, IL-1β, IL-6), TGF-β1, α-smooth muscle actin, collagen I, and p-Smad3 accumulation in human peritoneal mesothelial cells. Collectively, these results indicated that empagliflozin exerted a clear protective effect on high-glucose peritoneal dialysis-induced peritoneal fibrosis via suppressing TGF-β/Smad signaling.

Scavenging of reactive oxygen species by astaxanthin inhibits epithelial-mesenchymal transition in high glucose-stimulated mesothelial cells

BACKGROUND

High glucose concentrations influence the functional and structural development of the peritoneal membrane. We previously reported that the oral administration of astaxanthin (AST) suppressed peritoneal fibrosis (PF) as well as inhibited oxidative stress, inflammation, and epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in a chlorhexidine-induced PF rat model. This suggests that oxidative stress induction of EMT is a key event during peritoneal damage. The present study evaluated the therapeutic effect of AST in suppressing EMT, in response to glucose-induced oxidative stress.

METHODS

Temperature-sensitive mesothelial cells (TSMCs) were cultured in the presence or absence of AST and then treated with 140 mM glucose for 3 or 12 hours. Expression levels of TNF-α, TGF-β, and VEGF were determined at the mRNA and protein levels, and nuclear factor kappa B (NF-κB) activity was evaluated. We measured NO2-/NO3- concentrations in cellular supernatants and determined 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in mitochondrial and nuclear DNA. The expressions of E-cadherin and alpha-smooth muscle actin (α-SMA) were evaluated by double immunofluorescence and protein levels.

RESULTS

High glucose concentrations induced overproduction of reactive oxidative species (ROS), increasing 8-OHdG mitochondrial DNA and cytokine levels. The NF-κB pathway was activated in response to high glucose concentrations, whereas de novo α-SMA expression was observed with decreased E-cadherin expression. AST treatment attenuated ROS production, inflammatory cytokine production, NF-κB activation, and EMT.

CONCLUSION

The findings of the present study indicate that AST may have an anti-EMT effect due to anti-oxidative and anti-inflammatory activities by scavenging glucose-induced ROS from mitochondria in PMCs. AST may be an efficacious treatment for PF.

Mesothelial cell transplantation: history, challenges and future directions

Mesothelial cells line the surface of the pleura, pericardium, peritoneum and internal reproductive organs. One of their main functions is to act as a non-adhesive barrier to protect against physical damage, however, over the past decades their physiological and pathological properties have been revealed in association with a variety of conditions and diseases. Mesothelium has been used in surgical operations in clinical settings, such as omental patching for perforated peptic ulcers and in glutaraldehyde-treated autologous pericardium for aortic valve reconstruction. Various methods for mesothelial cell transplantation have also been established and developed, particularly within the area of tissue engineering, including scaffold and non-scaffold cell sheet technologies. However, the use of mesothelial cell transplantation in patients remains challenging, as it requires additional operations under general anesthesia in order to obtain enough intact cells for culture. Moreover, the current methods of mesothelial cell transplantation are expensive and are not yet available in clinical practice. This review firstly summarizes the history of the use of mesothelial cell transplantation in tissue engineering, and then critically discusses the barriers for the clinical application of mesothelial cell transplantation. Finally, the recent developments in xenotransplantation technologies are discussed to evaluate other feasible alternatives to mesothelial cell transplantation.

Colorectal cancer-promoting activity of the senescent peritoneal mesothelium

Gastrointestinal cancers metastasize into the peritoneal cavity in a process controlled by peritoneal mesothelial cells (HPMCs). In this paper we examined if senescent HPMCs can intensify the progression of colorectal (SW480) and pancreatic (PSN-1) cancers in vitro and in vivo. Experiments showed that senescent HPMCs stimulate proliferation, migration and invasion of SW480 cells, and migration of PSN-1 cells. When SW480 cells were injected i.p. with senescent HPMCs, the dynamics of tumor formation and vascularization were increased. When xenografts were generated using PSN-1 cells, senescent HPMCs failed to favor their growth. SW480 cells subjected to senescent HPMCs displayed up-regulated expression of transcripts for various pro-cancerogenic agents as well as increased secretion of their products. Moreover, they underwent an epithelial-mesenchymal transition in the Smad 2/3-Snail1-related pathway. The search for mediators of senescent HPMC activity showed that increased SW480 cell proliferation was stimulated by IL-6, migration by CXCL8 and CCL2, invasion by IL-6, MMP-3 and uPA, and epithelial-mesenchymal transition by TGF-β1. Secretion of these agents by senescent HPMCs was increased in an NF-κB- and p38 MAPK-dependent mechanism. Collectively, our findings indicate that in the peritoneum senescent HPMCs may create a metastatic niche in which critical aspects of cancer progression become intensified.

Oral Astaxanthin Supplementation Prevents Peritoneal Fibrosis in Rats

BACKGROUND

Preventing peritoneal damage during peritoneal dialysis is critical. Reactive oxygen species (ROS) have an important role in peritoneal damage; however, few studies have investigated this. We aimed to determine the effects of oral astaxanthin (AST) supplementation in a peritoneal fibrosis (PF) rat model.

METHODS

Thirty-seven Sprague-Dawley rats were divided into 5 groups: Control 1 (fed a normal diet without stimulation), Control 2 (fed an AST-supplemented diet without stimulation), Group 1 (fed a normal diet with 8% chlorhexidine gluconate [CG] stimulation for 3 weeks), Group 2 (fed a 0.06% AST-supplemented diet with CG stimulation), and Group 3 (fed a 0.06% AST-supplemented diet that was initiated 4 weeks before CG stimulation). Peritoneal fibrosis, vascular proliferation, and fibrosis-related factor expression were examined.

RESULTS

Peritoneal thickness was significantly suppressed by AST supplementation. Astaxanthin diminished the number of CD68-, 8-hydroxy-2'-deoxyguanosine (8-OHdG)-, and monocyte chemoattractant protein-1 (MCP-1)-positive cells. Type 3 collagen, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and MCP-1 mRNA expression was significantly lower in Group 3 than in Group 1. Increased transforming growth factor-β (TGF-β) and Snail mRNA expression, vascular density, and the number of α-smooth muscle actin (α-SMA)-positive cells were also decreased in Group 3.

CONCLUSION

Astaxanthin suppressed PF development through the inhibition of inflammation and oxidation in PF rats. It appears that the anti-oxidative agent AST may be useful for the prevention of peritoneal damage.