doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

Background & Aims: Detection of autoantibodies is a mainstay of diagnosing autoimmune hepatitis (AIH). However, conventional autoantibodies for workup of AIH lack either sensitivity or specificity leading to substantial diagnostic uncertainty. We aimed to identify more accurate serological markers of AIH with a protein macro-array. Approach & results: During the search for more precise autoantibodies to distinguish AIH from non-AIH liver diseases, IgG antibodies with binding capacities to many human and foreign proteins were identified with a protein macroarray and confirmed with solid phase ELISAs in AIH patients. Subsequently, polyreactive IgG (pIgG) were exemplarily quantified by reactivity against human huntingtin-interacting protein 1related protein in bovine serum albumin blocked ELISA (HIP1R/BSA). Diagnostic fidelity of HIP1R/BSA binding pIgG to diagnose AIH was assessed in a retrospective training, a retrospective multicenter validation and a prospective validation cohort, in cryo-conserved samples from 1568 adults from ten centers from eight countries. Reactivity against HIP1R/BSA had a 25% and 14% higher specificity to diagnose AIH than conventional anti-nuclear and antismooth muscle antibodies, a significantly higher sensitivity than liver kidney microsomal antibodies and anti-soluble liver antigen/liver pancreas antigen and a 12-20% higher accuracy than conventional autoantibodies. Importantly, HIP1R/BSA reactivity was present in up to 88 % of patients with seronegative AIH and in up to 71% of AIH patients with normal IgG levels. Under therapy pIgG returns to background levels of non-AIH liver diseases. Conclusions: pIgG could be used as a new promising marker to improve the diagnostic workup of liver diseases with a higher specificity for AIH compared to conventional autoantibodies and a utility in autoantibody negative AIH. Likewise, pIgG could be a major source of assay interference in untreated AIH.

Primary Sjögren’s syndrome (SS) is a systemic autoimmune disease characterized by lymphocytic infiltration and damage of exocrine salivary and lacrimal glands. The etiology of SS is complex with environmental triggers and genetic factors involved. By conducting an integrated multi-omics study, we confirmed a vast coordinated hypomethylation and overexpression effects in IFN-related genes, what is known as the IFN signature. Stratified and conditional analyses suggest a strong interaction between SS-associated HLA genetic variation and the presence of Anti-Ro/SSA autoantibodies in driving the IFN epigenetic signature and determining SS. We report a novel epigenetic signature characterized by increased DNA methylation levels in a large number of genes enriched in pathways such as collagen metabolism and extracellular matrix organization. We identified potential new genetic variants associated with SS that might mediate their risk by altering DNA methylation or gene expression patterns, as well as disease-interacting genetic variants that exhibit regulatory function only in the SS population. Our study sheds new light on the interaction between genetics, autoantibody profiles, DNA methylation and gene expression in SS, and contributes to elucidate the genetic architecture of gene regulation in an autoimmune population.

Objective To identify the genetic variants that affect gene expression (expression quantitative trait loci [eQTLs]) in systemic sclerosis (SSc) and to investigate their role in the pathogenesis of the disease. Methods We performed an eQTL analysis using whole‐blood sequencing data from 333 SSc patients and 524 controls and integrated them with SSc genome‐wide association study (GWAS) data. We integrated our findings from expression modeling, differential expression analysis, and transcription factor binding site enrichment with key clinical features of SSc. Results We detected 49,123 validated cis‐eQTLs from 4,539 SSc‐associated single‐nucleotide polymorphisms (SNPs) (PGWAS < 10−5). A total of 1,436 genes were within 1 Mb of the 4,539 SSc‐associated SNPs. Of those 1,436 genes, 565 were detected as having ≥1 eQTL with an SSc‐associated SNP. We developed a strategy to prioritize disease‐associated genes based on their expression variance explained by SSc eQTLs (r2 > 0.05). As a result, 233 candidates were identified, 134 (58%) of them associated with hallmarks of SSc and 105 (45%) of them differentially expressed in the blood cells, skin, or lung tissue of SSc patients. Transcription factor binding site analysis revealed enriched motifs of 24 transcription factors (5%) among SSc eQTLs, 5 of which were found to be differentially regulated in the blood cells (ELF1 and MGA), skin (KLF4 and ID4), and lungs (TBX4) of SSc patients. Ten candidate genes (4%) can be targeted by approved medications for immune‐mediated diseases, of which only 3 have been tested in clinical trials in patients with SSc. Conclusion The findings of the present study indicate a new layer to the molecular complexity of SSc, contributing to a better understanding of the pathogenesis of the disease.

1. While anti-Ro60 autoantibodies are among the most frequently detected extractable nuclear antigen autoantibodies, a signature common to all patients expressing anti-Ro60 autoantibodieshas not yet been established.4. Targeting Ro60-associated RNAs and Ro60-specific autoantibodies will reduce interferon signature in systemic autoimmune diseases.This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as