Systemic Lupus Erythematosus (?Lupus?) is a systemic autoimmune disease that leads to chronic inflammation in multiple organs including the kidneys. Patients commonly have exacerbations of the disease (kidney nephritis ?flares?) interspersed by quiescent intervals. Early detection and the prompt treatment of flares can have a significant impact on the health and survival of patients, who are disproportionately female, Hispanic, and/or African-American. Biopsy sampling of kidney tissues is the gold standard for Lupus diagnosis, but is invasive and cannot be repeated frequently. In this context, blood or urine biomarkers that are predictive of kidney pathology could be very useful, especially if they supported point-of-care or ideally at-home testing. We have discovered and extensively validated lupus flare-correlated blood and urine diagnostic biomarkers in a protein screen of unprecedented scale, extending across 4 ethnic groups of patients (African American, Caucasian, Hispanic and Chinese). The urine markers perform better than conventional laboratory markers for Lupus and show potential to track with disease activity over time. While urine is an easy sample to give, urine biomarker concentrations must be corrected for their dilution by urine production. The molecule traditionally used for normalizing for urinary dilution, creatinine, is not very compatible with standard immunoassays, but we have identified a protein whose concentration in urine closely correlates with that of creatinine and that can be measured along with the flare markers. A point-of-care (Doctor's office), or better yet, a home self-test, for lupus flares could improve outcomes by expediting treatment. The natural format for such a test would be the lateral-flow assay (LFA), which is widely used as the home pregnancy test. Current LFAs, however, either require expensive equipment or lack the necessary sensitivity and quantitation. We propose to address this problem with smartphone-based LFAs based on our new phosphorescent (?glow-in-the-dark?) nanoparticle reporters. Motivating hypothesis: We hypothesize that the increased sensitivity and quantification ability of nanophosphor-LFAs will enable patients or doctors to simply measure our new kidney nephritis flare biomarkers in urine, and thus, address the unmet need for clinic/home monitoring of lupus nephritis flares. Successful completion of this work also will provide a generally-useful platform technology for quantitative smartphone LFA tests requiring no elaborate phone modifications (only a $10 slide-on attachment), and a new method of urine marker normalization well suited to general use in LFA and ELISA.
Specific Aims : We propose:
(Aim 1) To develop quantitative LFAs for urinary flare markers and creatinine-correlated normalizing protein;
(Aim 2) To integrate multiple marker and normalizing protein tests into a user-friendly system with software error-catching, barcode reading, and quality controls; and finally (Aim 3) To evaluate the performance of the tests in lupus, using urine samples from broad cohorts of patients.
The proposed research is relevant to the public health because it aims to replace infrequent, invasive renal biopsies with simple urine tests for flares of Systemic Lupus Erythematosus (?Lupus?) nephritis. The test will use ?glow-in-the-dark? nano-particles to enable sensitive and quantitative measurements on a smartphone with a $10 attachment. This new platform will support widespread use of cell phone-based sensitive, quantitative diagnostics.