Proteomic profile of mesothelial exosomes isolated from peritoneal dialysis effluent of children with focal segmental glomerulosclerosis

Abstract

Peritoneal dialysis (PD) is the worldwide recognized preferred dialysis treatment for children affected by end-stage kidney disease (ESKD). However, due to the unphysiological composition of PD fluids, the peritoneal membrane (PM) of these patients may undergo structural and functional alterations, which may cause fibrosis. Several factors may accelerate this process and primary kidney disease may have a causative role. In particular, patients affected by steroid resistant primary focal segmental glomerulosclerosis, a rare glomerular disease leading to nephrotic syndrome and ESKD, seem more prone to develop peritoneal fibrosis. The mechanism causing this predisposition is still unrecognized. To better define this condition, we carried out, for the first time, a new comprehensive comparative proteomic mass spectrometry analysis of mesothelial exosomes from peritoneal dialysis effluent (PDE) of 6 pediatric patients with focal segmental glomerular sclerosis (FSGS) versus 6 patients affected by other primary renal diseases (No FSGS). Our omic study demonstrated that, despite the high overlap in the protein milieu between the two study groups, machine learning allowed to identify a core list of 40 proteins, with ANXA13 as most promising potential biomarker, to distinguish, in our patient population, peritoneal dialysis effluent exosomes of FSGS from No FSGS patients (with 100% accuracy). Additionally, the Weight Gene Co-expression Network Analysis algorithm identified 17 proteins, with PTP4A1 as the most statistically significant biomarker associated to PD vintage and decreased PM function. Altogether, our data suggest that mesothelial cells of FSGS patients are more prone to activate a pro-fibrotic machinery. The role of the proposed biomarkers in the PM pathology deserves further investigation. Our results need further investigations in a larger population to corroborate these findings and investigate a possible increased risk of PM loss of function or development of encapsulating peritoneal sclerosis in FSGS patients, thus to eventually carry out changes in PD treatment and management or implement new solutions.

Extracellular Vesicles of Patients on Peritoneal Dialysis Inhibit the TGF-β- and PDGF-B-Mediated Fibrotic Processes

“…According to our extensive analysis, the morphology, size distribution, as well as the protein-to-lipid ratio of the isolated PDE-EVs corresponded to typical EVs (Figure 2). Moreover, PDE-EVs were positive for the known EV-specific proteins, including annexin, CD9, CD63, HSP70, and for E-cadherin and CK-18, which is consistent with the previous work by Bruschi et al [16], Corciulo et al [17], and Huang et al [33], suggesting that the isolated PDE-EVs are of the mesothelial origin (Figure 2).…”

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

“…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.…”

Extracellular Vesicles as Source of Biomarkers in Glomerulonephritis

“…Our first comprehensive proteomic analysis assayed mesothelial sEVs from peritoneal dialysis (PD) effluent of subjects affected by FSGS, in comparison to subjects bearing other KDs. PTP4A1 was the most statistically significant biomarker associated with PD vintage and loss of peritoneal membrane function, caused by peritoneal fibrosis, due to the unphysiological composition of PD fluids [ 82 ]. As peritoneal fibrosis is a frequent evolution of PD, which can limit the efficacy of dialytic treatment [ 82 ], it would be useful to validate PTP4A1 as a prognostic biomarker to predict the progression of renal fibrosis in PD.…”

“…PTP4A1 was the most statistically significant biomarker associated with PD vintage and loss of peritoneal membrane function, caused by peritoneal fibrosis, due to the unphysiological composition of PD fluids [ 82 ]. As peritoneal fibrosis is a frequent evolution of PD, which can limit the efficacy of dialytic treatment [ 82 ], it would be useful to validate PTP4A1 as a prognostic biomarker to predict the progression of renal fibrosis in PD. ANXA13, the founder member of the annexin (ANX) family, was able to distinguish with 100% accuracy sEVs from PD effluent from FSGS patients versus those without FSGS [ 103 ].…”