Systemic lupus erythematosus (SLE) is a systemic autoimmune connective disease in which the immune system attacks its own structures, causing widespread inflammation and tissue damage in the affected organs. The kidney is one of the main organs affected by SLE, and lupus nephritis (LN) concerns 3060% of adult SLE patients, being significantly associated with an increase in morbidity and mortality. The definitive diagnosis of LN can only be achieved by histological analysis of renal biopsies, but the invasiveness of this technique is an obstacle for early diagnosis of renal involvement and a proper follow-up of LN patients under treatment. Our aim to identify minimally invasive biomarkers of renal involvement and non-response to therapy in SLE using body fluid (urine and blood), using cutting-edge technologies related with flow cytometry: blood mass cytometry, urinary inflammatory mediators, extracellular vesicle analysis and urinary microbiome. The tissue/fluid correlation will be assessed using kidney biopsy samples following a liquid biopsy approach. We will apply this analysis to longitudinal samples of LN patients recruited in 3TR consortium, and finally design a prototype kit for LN diagnosis and prognosis. With this project EARLINESS participate in the efforts of the scientific community to develop effective strategies for personalized rheumatology.