Ms CHIN-YA SOPHIE CHIANG1, Dr. XIANGJU WANG1, Dr. HELEN GRANIA HEALY1,2,3, Dr. ANDREW J KASSIANOS1,3, Dr. MONICA SUET YING NG1,2,3
1Kidney Health Service, Royal Brisbane and Women’s Hospital, Herston, Brisbane, Australia, 2Faculty of Medicine, University of Queensland, Herston, Brisbane, Australia, 3Conjoint Internal Medicine Laboratory, Chemical Pathology, Pathology Queensland, Herston, Brisbane, Australia
Biography:
Chin-Ya Sophie Chiang is a predoctoral research scientist at the Conjoint Internal Medicine Laboratory’s Translational Kidney Pathobiology Group, with a research interest in the analysis of extracellular vesicles in kidney diseases-related pathophysiology and the development of non-invasive diagnostic tests with extracellular vesicles in kidney diseases. She completed Bachelor of Biomedical Science Honours at University of Queensland in 2023 in extracellular vesicles in cancer.
Aim:
To profile the expression of proximal tubule-specific proteins on urine extracellular vesicles (EVs).
Background:
Kidney cells express segment-specific surface proteins that can indicate nephron origin. However, whether these markers are retained on urinary EVs and can be used to infer their tubular source remains unclear.
Method:
Kidney-enriched urine EV surface proteins were selected using a bioinformatic-driven approach integrating Vesiclepedia, UniProt and Human Protein Atlas. Nephron-segment specific expression of urine EV proteins was annotated using the Kidney Precision Medicine Project (KPMP) which contains annotated single cell sequencing data from human kidney tissue. Urine EVs were isolated from healthy controls (n=5) by urine concentration (centrifugal filter or ultracentrifugation), followed by size exclusion chromatography and ultracentrifugation. Urine EVs were characterised using tunable resistive pulse sensing (size/concentration) and electron microscopy (morphology). Expression of tubule cell proteins was assessed on urine EVs and patient-derived proximal tubule epithelial cells (PTECs) using spectral flow cytometry.
Results:
The median number of urine EVs was 4.05×10¹⁰particles/µmol creatinine (IQR 3.37×10¹⁰- 6.33×10¹⁰particles/µmol creatinine). Expression of seven proximal tubule markers (CD10, CD13, ATP1B1, DPEP, PDZK1, CUBN, CDH16) was confirmed in patient-derived PTECs. Distal tubule marker MUC1 was included as negative control. Of these proximal tubule markers, four were detectable on urine EVs: CD10 (6.58×10⁴ EVs/µmol creatinine), CD13 (7.55×10³ EVs/µmol creatinine), CUBN (1.08×10⁶ EVs/µmol creatinine) and CDH16 (2.35×10⁵ EVs/µmol creatinine). MUC1 was identified on 7.27×10⁶ EVs/µmol creatinine.
Conclusions:
The differential expression of proximal tubule markers between PTECs and urine EVs suggests selective incorporation of surface proteins into urine EVs. These findings support the feasibility of using surface profiling to identify tubular segment origin in urine EVs and warrant further investigation in disease states to localise tubular injury.