Short summary

Lupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus (SLE) that can lead to irreversible kidney damage if not detected and managed promptly. LN is classified and treated based on its histopathological features obtained by invasive kidney biopsy. Recent research has suggested urinurinary extracellular vesicles (uEVs) as potential non-invasive biomarkers. The primary objective of this prospective study is to investigate the utility of uEVs in LN.

Rationale

Lupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus (SLE) that can lead to irreversible kidney damage if not detected and managed promptly. LN is classified based on its histopathological features. The classification helps in determining the severity and appropriate treatment strategies for the condition and to rule out other conditions that may mimic the clinical picture of LN. The classification requires invasive kidney biopsies, which are hardly accessible and associated with potential complications and patient discomfort. Furthermore the kidney biopsies only represent a small part of the kidney. Recent research has suggested urinary extracellular vesicles (uEVs) as potential non-invasive biomarkers for kidney diseases, including LN. uEVS are small nano-sized extracellular vesicles of endosomal origin, which are secreted into the urine through fusion of multivesicular bodies with the plasma membrane. Thus, they could represent a promising liquid biopsy that reflects the pattern and/or severity of renal histologic injury. This prospective study aims to establish urinary exosomes as potential non-invasive biomarkers for monitoring lupus nephritis in SLE patients. The findings from this research may lead to the development of more efficient and patient-friendly approaches for LN management, enabling timely interventions and improved renal outcomes in SLE patients.

Description of the cohort

SLE patients, fulfilling the 2019 EULAR/ACR classification criteria, referred to kidney biopsy, will be recruited from Department of Rheumatology and Department of Nephrology at Odense University Hospital. A biopsy control group with no predictive complement activation referred to biopsy will be included in Lillebaelt Hospital, Kolding. Urine and blood samples from healthy controls and SLE patients will be included as well. N=10 will be included in each group, based on previous studies our power calculation.

Data and biological material

Detailed demographic and clinical data including age, sex, ethnicity, medicine, duration of SLE activity, SLE damage and laboratory results will be collected from each patient. Activity of SLE at the time of biopsy will be evaluated using SLE disease activity index 2000 (SLEDAI-2K). SLE damage will be evaluated in accordance with the SLICC damage index. Spot-urine samples will be collected, added protease-inhibitors and frozen at -80 degree. Urinary extracellular vesicles will be isolated using polyethylene glycol (PEG) precipitation, the concentration of uEV will be determined and protein accessed using western blotting and/or PCR. Glomerular specific uEVs will be isolated and previous developed tests will be applied to detect the membrane attack complex (MAC)/C5b-9 complex5. uEVs from plasma/serum will be isolated to test for correlation with uEVs. Kidney biopsies will be histological analyzed at department of Pathology by experienced nephro-pathologists according to existing clinical guidelines.

Collaborating researchers and departments

Departent of Cardiocascular And Renal Research, University of Southern Denmark

• Per Svenningsen, professor

Department of Rheumatology, Odense University Hospital

• Anne Voss
• Henrik Zachar Langkilde

Department of Nephrology, Odense University hospital

• Michael Aarup
• Department of Cancer and Inflammation

Department of Cancer and Inflammation, University of Southern Denmark

• Yaseelan Palarasah

Department of Clinical Pathology, University of Southern Denmark

• Kirsten Madsen