Identification of New Autoantigens by Protein Array Indicates a Role for IL4 Neutralization in Autoimmune Hepatitis

Chiara Zingaretti, Milena Arigò, Angela Cardaci, Monica Moro, Mariacristina Crosti, Antonella Sinisi, Elisa Sugliano, Cristina Cheroni, Francesco Marabita, Renzo Nogarotto, Raoul Jean Pierre Bonnal, Paolo Marcatili (+13 others)
2012 Molecular & Cellular Proteomics  
Autoimmune hepatitis (AIH) is an unresolving inflammation of the liver of unknown cause. Diagnosis requires the exclusion of other conditions and the presence of characteristic features such as specific autoantibodies. Presently, these autoantibodies have relatively low sensitivity and specificity and are identified via immunostaining of cells or tissues; therefore, there is a diagnostic need for better and easy-to-assess markers. To identify new AIHspecific autoantigens, we developed a protein
more » ... microarray comprising 1626 human recombinant proteins, selected in silico for being secreted or membrane associated. We screened sera from AIH patients on this microarray and compared the reactivity with that of sera from healthy donors and patients with chronic viral hepatitis C. We identified six human proteins that are specifically recognized by AIH sera. Serum reactivity to a combination of four of these autoantigens allows identification of AIH patients with high sensitivity (82%) and specificity (92%). Of the six autoantigens, the interleukin-4 (IL4) receptor fibronectin type III domain of the IL4 receptor (CD124), which is expressed on the surface of both lymphocytes and hepatocytes, showed the highest individual sensitivity and specificity for AIH. Remarkably, patients' sera inhibited STAT6 phosphorylation induced by IL4 binding to CD124, demonstrating that these autoantibodies are From the ‡Istituto Nazionale Genetica Molecolare (INGM), 20122 Milan, Italy; ¶Externautics S.p.A., 1 The abbreviations used are: AIH, autoimmune hepatitis; AUC, area under the curve; DELFIA, Dissociation-enhanced Lanthanide Fluoroscence ImmunoAssay; FNIII, fibronectin type III domain; HBV, hepatitis B virus; HCV, hepatitis C virus; HD, healthy donor; IL4R, interleukin-4 receptor; IMAC, immobilized metal ion affinity chromatography; MFI, mean fluorescence intensity; PAM, predictive analysis of microarray; ROC, Receiver Operating Characteristic. Research
doi:10.1074/mcp.m112.018713 pmid:22997428 pmcid:PMC3518104 fatcat:rq7xexgq7bet3dl6nwu7aifklu