Aditi Saxena

BACKGROUND: Infection by Trypanosoma cruzi , the agent of Chagas disease, is endemic to the Americas and can irreparably damage the cardiac and gastrointestinal systems during decades of parasite persistence. Diagnosis of chronic infection requires confirmation by multiple serological assays due to the imperfect performance of existing tests. Current serology tests were developed using small specimen sets predominantly from South America, and lower performance has been observed in patients who acquired infection in Central America and Mexico. METHODS: To improve Chagas disease serology, we evaluated antibody responses against the entire T . cruzi proteome with phage display immunoprecipitation sequencing and further evaluated high-prevalence antigens by immunoassay. We utilized specimen sets representing Mexico, Central America, and South America and varying cardiac disease presentations, from 185 cases and 143 controls. RESULTS: We identified over 1,300 antigenic T . cruzi peptides. A trans-sialidase antigen demonstrated high seroprevalence across all regions and has not previously been described as a diagnostic target to our knowledge. Orthogonal validation of this peptide demonstrated increased antibody reactivity for infections originating from Central America. CONCLUSION: This study provides proteome-wide identification of seroreactive T . cruzi peptides across a range of endemic populations not previously represented in antigen discovery and identifies a trans-sialidase peptide antigen (TS23) with potential for translation into diagnostic serological assays. FUNDING: Chan Zuckerberg Biohub, the Chan Zuckerberg Biohub Physician-Scientist Fellowship Program, the NIH National Heart Lung and Blood Institute award K38HL154203, and the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development award F30HD117526.

Given the global surge in autoimmune diseases, it is critical to evaluate emerging therapeutic interventions. Despite numerous new targeted immunomodulatory therapies, comprehensive approaches to apply and evaluate the effects of these treatments longitudinally are lacking. Here, we leveraged advances in programmable-phage immunoprecipitation methodology to explore the modulation, or lack thereof, of autoantibody profiles, proteome-wide, in both health and disease. Using a custom set of over 730,000 human-derived peptides, we demonstrated that each individual, regardless of disease state, possesses a distinct and complex constellation of autoreactive antibodies. For each individual, the set of resulting autoreactivites constituted a unique immunological fingerprint, or “autoreactome,” that was remarkably stable over years. Using the autoreactome as a primary output, we evaluated the relative effectiveness of various immunomodulatory therapies in altering autoantibody repertoires. We found that therapies targeting B cell maturation antigen (BCMA) profoundly altered an individual’s autoreactome, while anti-CD19 and anti-CD20 therapies had minimal effects. These data both confirm that the autoreactome comprises autoantibodies secreted by plasma cells and strongly suggest that BCMA or other plasma cell–targeting therapies may be highly effective in treating currently refractory autoantibody-mediated diseases.