Glycoprotein 96 in Peritoneal Dialysis Effluent-Derived Extracellular Vesicles: A Tool for Evaluating Peritoneal Transport Properties and Inflammatory Status

Abstract

BackgroundExtracellular vesicles (EVs) from peritoneal dialysis effluent (PDE), containing molecules such as proteins and microRNAs (miRNAs), may be potential biological markers to monitor peritoneal function or injury. Peritoneal inflammation is an important determinant of peritoneal solute transport rate (PSTR). Thus, the aim of this study is to determine whether the specific proteins capable of evaluating the PSTR could be found in PDE-EVs, and explore the underlying mechanism for the association between PSTR and peritoneal inflammation.MethodsSixty patients undergoing peritoneal dialysis (PD) were divided into two groups: high/high average transport (H/A) group (PET >0.65) and low/low average transport (L/A) group (PET <0.65). EVs derived from PDE (PDE-EVs) were isolated by ultracentrifugation. Proteomic analysis was performed to explore the differentially expressed proteins and identify the potential biomarkers in PDE-EVs from the two groups, and we focused on glycoprotein 96 (GP96) as it could be involved in the inflammatory process. The expression of GP96 in PDE-EVs and inflammatory cytokines was quantified by real-time PCR and enzyme-linked immunosorbent assay. The infiltration of macrophages and neutrophils into the peritoneum was detected using immunohistochemistry in a PD rat model.ResultsThe expression of PDE-EVs-GP96 was significantly higher in the H/A group, and was positively correlated with the PSTR and the level of the inflammatory factor interleukin (IL)-6. GP96-enriched EVs enhanced the secretion of proinflammatory cytokines IL-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 in macrophages, which was reversed by a pharmacological GP96-specific inhibitor (PU-WS13). The GP96 inhibitor also reduced local peritoneal inflammation by decreasing the infiltration of inflammatory cells and levels of proinflammatory cytokines (IL-6 and TNF-α) and chemokines (CCL2, CXCL1, and CXCL2) in a PD rat model.ConclusionsPDE-EVs-GP96 is a new promising tool to evaluate the status of peritoneal inflammation and PSTR, and the mechanism may be related to affecting the inflammatory properties of macrophages.

Extracellular vesicle‐packaged ILK from mesothelial cells promotes fibroblast activation in peritoneal fibrosis

“…The fact that EVs can be found in PD effluent offers a glimpse into the pathological state of peritoneal cells. In previous studies, effluent‐derived EVs in patients undergoing PD with high/high average transport (H/HA) or low/low average transport (L/LA) presented distinct protein expression profiles (Fang et al., 2022 ). Our data further demonstrated that proteins in LPD‐EVs are enriched in the pathways relevant to fibrosis and metabolism, suggesting the dynamical alteration of EVs in abdominal cavity microenvironment.…”

“…Studies have shown that PD effluent-derived EVs are positive for the mesothelial marker mesothelin, supporting that mesothelial cells may be one of the sources of these EVs (Bruschi et al, 2021;Fang et al, 2022). However, using single cell marker to determine the source of PD effluent-derived EVs is not sufficient, and the specific cell sources of these EVs remain largely unknown.…”

“…For example, exosomes containing aquaporin 1 from PD effluent can properly reflect dialysis efficiency and the status of peritoneum (Corciulo et al., 2019 ). Similarly, EVs‐packaged glycoprotein 96 from PD effluent is also a potential biomarker of the peritoneal solute transport rate (Fang et al., 2022 ). Although these studies reflected the diagnostic value of EVs during PD, the information of whether and how EVs make use of their molecular cargos to influence the development of peritoneal fibrosis is still lacking.…”

Proteomics and Extracellular Vesicles as Novel Biomarker Sources in Peritoneal Dialysis in Children

“…Successively, the researchers validated their results in vitro, showing that GP96 increased the secretion of proinflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-18) in peritoneal derived macrophages and in a PD rat model where the GP96 inhibition reduced peritoneal inflammation response through the reduction of inflammatory cells, cytokines, and chemokines (CCL2, CXCL1, and CXCL2). Their findings suggest that GP96 can be a potential indicator of peritoneal inflammation and PSTR in PD patients [ 62 ]. In the latest years, among the other extracellular vesicles, the analysis of exosomes has earned the greatest interest in the field of new diagnostic and therapeutic possibilities [ 63 ].…”

Proteomic Characterization of Peritoneal Extracellular Vesicles in a Mouse Model of Peritoneal Fibrosis

“…These PD effluent-derived EV proteomes showed alteration earlier than peritoneal equilibration test monitoring, suggesting the potential of EV proteins as biomarkers of peritoneal function alteration for patients undergoing PD . Moreover, it has been reported that specific molecular cargo in EVs, such as aquaporin 1 and glycoprotein 96, can be used to evaluate the status of peritoneum. , …”