Ms Chin-Ya Sophie Chiang1,2, Dr Jasmin Straube3, A/Prof Helen Healy1,2,4, Dr Andrew Kassianos1,2, Dr Monica Suet Ying Ng1,2,4
1Kidney Health Service, Royal Brisbane And Women’s Hospital, Herston, Australia, 2Conjoint Internal Medicine Laboratory, Chemical Pathology, Pathology Queensland, Herston, Australia, 3QIMR Berghofer, Herston, Australia, 4Faculty of Medicine, University of Queensland, Herston, Australia
Biography:
Dr Monica Ng is a staff specialist nephrologist and early career clinician scientist at the Royal Brisbane and Women’s Hospital. Dr Ng graduated from UQ in 2014 with MBBS with first class honours. She completed her PhD studies in 2019. Since then, her research has focused on the clinical application of extracellular vesicles for kidney disease; kidney disease epidemiology and management of chronic kidney disease.
Aim:
To determine the multi-omic signature of urine extracellular vesicles (EVs) from people with chronic kidney disease (CKD) that can be leveraged for novel non-invasive tests.
Background:
Urine EVs carry molecular cargoes reflecting the subcellular health/disease status of the donor cell – making them effective biomarkers in liquid biopsies such as urine.
Methods:
Urine was collected from healthy controls (n=5) and people with CKD (n=11). Urine EVs were isolated using size exclusion chromatography and ultracentrifugation. Urine EVs were confirmed using electron microscopy (morphology) and tunable resistive pulse sensing (size/concentration). Messenger RNA (mRNA) was assessed using next generation sequencing. Kidney tubule cell proteins (CD13, CD10, MUC1, CDH16) were assessed using flow cytometry. Urine EV markers were correlated with degree of histological (kidney fibrosis; interstitial fibrosis and tubular atrophy [IFTA]) and clinical CKD.
Results:
EVs from CKD stage 3b/4 were elevated compared to healthy controls (median 5.28×10¹⁰ EVs/μmol creatinine versus 1.42×10¹⁰ EVs/μmol creatinine, p <0.05) with increased urine EVs expressing proximal tubular marker (CD13) from CKD stage 3b/4 compared to healthy controls (2.43×10⁵ EVs/μmol creatinine versus 1.21×10³ EVs/μmol creatinine, p=0.004). There were increased urine EVs from fibrotic kidneys compared to non-fibrotic kidneys (1.37×10¹⁰ EVs/ml urine versus 1.45×10⁸ EV/ml urine). There were 302 upregulated mRNAs and 18 downregulated mRNAs in urine EVs from severe kidney fibrosis (IFTA>25%) compared to mild kidney fibrosis (IFTA 0-5%), including several upregulated mRNAs (e.g. ALDOB, GPX3, SPP1, VIM) observed in a Finnish cohort of diabetic CKD.
Conclusions:
Urine EVs carry unique mRNA and protein markers that can be used to grade degree of kidney fibrosis and CKD. Multi-centre studies are ongoing to confirm findings and additional markers are being assessed using flow cytometry.