Dialysate copeptin and peritoneal transport in incident peritoneal dialysis patients

Profiling cytokines in peritoneal effluent through a targeted multiplex cytokine panel provides novel insight into the localized proinflammatory processes in patients undergoing peritoneal dialysis

Objectives

The number of relevant markers indicating local intraperitoneal inflammation in patients undergoing peritoneal dialysis (PD) is limited. Therefore, this study aimed to evaluate the compatibility of peritoneal effluent (PE) for proteomic analysis and assess its potential utility in immunoprofiling studies.

Methods

This pilot study included six PD patients from the Peritoneal Dialysis Center, Department of Nephrology, Transplantology, and Internal Medicine in Szczecin, Poland. All patients were clinically stable, with no signs of infections or malignancy at the time of study. PE samples were collected during routine surveillance visits at the Peritoneal Dialysis Center. Proteomic analysis of the samples was conducted using the Olink® (Olink Proteomics AB, Uppsala, Sweden) Target 48 Cytokine panel.

Results

PE samples were successfully analyzed, with 28 out of 45 proteins found within the limit of quantitation (LOQ) and 32 out of 45 proteins detected above the limit of detection (LOD). No significant interference from the matrix was observed in the assay. Biomarkers associated with low-grade inflammation showed varied levels, and the observed patterns were comparable across all patients.

Conclusion

This study suggests that utilizing a cytokine panel with relative quantification is a promising method for PE immunoprofiling.

The role of copeptin in kidney disease

Copeptin is a 39-amino acid glycopeptide that is secreted equimolecularly with arginine-vasopressin (AVP) from the prepro-hormone AVP in the posterior pituitary. While AVP is a very unstable molecule and is accompanied by significant technical troubles in its quantification, copeptin is a stable and easily quantifiable molecule. For this reason, circulating copeptin is currently used as a surrogate for AVP in different pathological conditions, including renal diseases. In recent years it has been shown that copeptin is associated with an increased risk of developing chronic kidney disease in the general population. In addition, copeptin has also been associated with multiple renal diseases with relevant clinical consequences and potential therapeutic implications. In the present review, we update and summarize the clinical significance of copeptin as a surrogate marker for AVP concentrations in different kidney diseases, as well as in renal replacement therapy (hemodialysis and peritoneal dialysis) and renal transplantation.

Copeptin is independently associated with vascular calcification in chronic kidney disease stage 5

BACKGROUND

Vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD) present in 30-70% of patients with chronic kidney disease (CKD). Copeptin is a sensitive surrogate marker of arginine vasopressin (AVP), which is involved in many pathophysiologic processes in CKD. The aim of the present study was to explore the association of copeptin with VC in CKD stage 5.

METHODS

Copeptin was investigated in conjunction with living donor kidney transplantation in 149 clinically stable CKD stage 5 patients (CKD5), including 53 non-dialyzed (CKD5-ND) and 96 dialysis patients treated by peritoneal dialysis (PD) (n = 43) or hemodialysis (HD) (n = 53). We analyzed the association of copeptin with presence and extent of VC ascertained both histologically in biopsies from the inferior epigastric artery (n = 137) and by coronary artery calcification (CAC) score measured by computed tomography.

RESULTS

Patients with higher copeptin were older, had higher systolic blood pressure, higher prevalence of CVD and their preceding time on chronic dialysis was longer. In Spearman's rank correlations (Rho), copeptin concentrations were significantly associated with CAC score (Rho = 0.27; p = 0.003) and presence of medial VC (Rho = 0.21; p = 0.016). Multivariate logistic regression analysis showed that 1-SD higher age, male gender, diabetes and 1-SD higher copeptin were significantly associated with the presence of moderate-extensive VC.

CONCLUSIONS

High circulating levels of copeptin in CKD5 patients are independently associated with the degree of medial calcification ascertained by histology of arterial biopsies. Thus, plasma copeptin may serve as a marker of the uremic calcification process.