Urinary Clusterin is a biomarker of renal epithelial senescence and predicts human kidney disease progression

Cellular senescence drives organ fibrosis and ageing, and accumulating evidence supports the ability of senescence-depleting drugs to improve outcomes in experimental models of disease. The lack of non-invasive biomarkers represents a major obstacle to the design of human trials of candidate senolytics. On samples from 51 patients with chronic kidney disease (CKD), we performed liquid chromatography mass spectrometry (LC-MS) analysis of urine samples alongside immunofluorescence staining of paired kidney biopsies for p21, Ki67, and CD10+Pancytokeratin as senescence, proliferation and pan-epithelial cell markers respectively. Only Urinary Clusterin (uClusterin) correlated tightly with p21+ epithelial senescence in vivo (rho >0.5, p<0.001) and was upregulated in the in vitro SASP atlas. This was validated in a second cohort of matched urine and kidney samples from n=53 participants, with uClusterin predicting levels of senescence after adjusting for renal function, age and albuminuria. In spatial transcriptomic data from n=13 CKD patients, Clusterin colocalised with senescence marker CDKN1A. In a larger cohort of n=322 participants, elevated levels of uClusterin predicted CKD progression (defined as reaching ESKD or >40% reduction in renal function) after adjusting for baseline eGFR, albuminuria, age, systolic blood pressure (SBP) and sex. uClusterin levels represents a surrogate for histological quantification of p21+Ki67- senescent renal epithelia and predicts outcomes in human kidney disease independent of existing clinical risk factors. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement DB is supported by MR/W00089X/1, DF is supported by MR/X006735/1. seNSOR is funded by RP\_042\_20160304 awarded to LD. LD is supported by SF\_001\_20181122 ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Offices of Research Ethics Committees for the Royal Infirmary of Edinburgh and Queen Elizabeth University Hospital, Glasgow give ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.