The Screening and Application of Biomarkers in Autoimmune Disease

This research portrays three aspects of the biomarker development pipeline: screening for stool biomarkers for pediatric inflammatory bowel disease (pIBD), validation of urine normalizer proteins, and translation of lupus nephritis (LN) urine biomarkers to phosphor-based lateral flow assays (LFAs). As the diagnosis of pIBD is invasive and painful for children, two high- throughput technologies utilizing aptamers and antibodies have been used to screen over 1000 human proteins for noninvasive stool biomarkers for the two types of pIBD: Crohn’s disease (CD) and ulcerative colitis (UC). The screens have uncovered 119 proteins elevated in both CD and UC stool, 19 proteins elevated in CD stool, 124 proteins elevated in UC stool, and 58 proteins dysregulated between CD and UC stool. ELISA validation of 23 proteins has uncovered 9 biomarkers for IBD, 1 biomarker for CD, 9 biomarkers for UC, and 10 biomarkers that distinguish UC from CD. Many hits have been implicated in the intestinal mucosa of pIBD patients and in inflammatory and other immunologic disease pathways. These biomarkers can aid in pIBD diagnosis and help elucidate the mechanisms of this complicated disease. To increase the sensitivity of urine biomarkers in diagnostics, most quantitative biomarkers are normalized to creatinine to account for urine production. Creatinine is a small metabolite and antibodies to creatinine are difficult to develop, limiting the applications of quantitative urine diagnostics. An aptamer screen of 1000 proteins and ELISA validation has identified HVEM for the normalization of ALCAM and other urine biomarkers for LN. To translate urine protein biomarkers for LN diagnostics to the point-of-care, sensitive and quantitative phosphor LFAs for the detection of ALCAM, an LN biomarker, and HVEM, a urine normalizer, have been created and optimized showing a limit of detection of 125 pg/mL in buffer. As this is the first application of nanophosphors in urine, the feasibility of nanophosphor use in urine has been evaluated and optimized showing detection limits around 5 ng/ml in urine. Although the current limit for the assay in urine is above the clinical range of ALCAM and HVEM, this work has created a foundation for the application of nanophosphors for the detection of urinary ALCAM and HVEM.