Functional Analysis of Autoantibody Signatures in Rheumatoid Arthritis.

Lisa Milchram,Stephan Blüml,Daniela Sieghart,Jasmin Huber,Regina Soldo,Klemens Vierlinger,Anita Fischer,Günter Steiner,Andreas Weinhäusel

doi:10.3390/molecules27041452

Abstract

For the identification of antigenic protein biomarkers for rheumatoid arthritis (RA), we conducted IgG profiling on high density protein microarrays. Plasma IgG of 96 human samples (healthy controls, osteoarthritis, seropositive and seronegative RA, n = 24 each) and time-series plasma of a pristane-induced arthritis (PIA) rat model (n = 24 total) were probed on AIT’s 16k protein microarray. To investigate the analogy of underlying disease pathways, differential reactivity analysis was conducted. A total of n = 602 differentially reactive antigens (DIRAGs) at a significance cutoff of p < 0.05 were identified between seropositive and seronegative RA for the human samples. Correlation with the clinical disease activity index revealed an inverse correlation of antibodies against self-proteins found in pathways relevant for antigen presentation and immune regulation. The PIA model showed n = 1291 significant DIRAGs within acute disease. Significant DIRAGs for (I) seropositive, (II) seronegative and (III) PIA were subjected to the Reactome pathway browser which also revealed pathways relevant for antigen presentation and immune regulation; of these, seven overlapping pathways had high significance. We therefore conclude that the PIA model reflects the biological similarities of the disease pathogenesis. Our data show that protein array analysis can elucidate biological differences and pathways relevant in disease as well be a useful additional layer of omics information.

Highlights

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by the presence of auto-reactive B- and T-cells, autoantibodies and increased cytokine release which all together lead to chronic joint inflammation
To elucidate and investigate auto-antibody signatures of rheumatoid factor (RF)- and CCP-positive and -negative rheumatoid arthritis and the pristane-induced arthritis (PIA) rodent model described by Tuncel et al, IgG probing was conducted on high density protein microarrays
Data extracted from microarray images were analysed for differentially reactive antigens (DIRAGs) between seropositive and seronegative rheumatoid arthritis (RA) and samples of the PIA rat model upon the disease onset period

Summary

Introduction

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by the presence of auto-reactive B- and T-cells, autoantibodies and increased cytokine release which all together lead to chronic joint inflammation. The serological diagnosis is based on the presence of rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPAs) [2]. Besides the known advantages and limitations of these models, currently no comparative analysis of auto-antibody signatures for RA and its respective animal models can be found within the literature. Among these models pristane-induced arthritis (PIA) is of particular interest, because arthritogenic autoimmunity is induced in rats by the application of the non-immunogenic mineral oil pristane (2,6,10,14-Tetramethylpentadecane). PIA shows many features which are similar to human RA, such as chronic synovitis, cartilage degradation, bone erosions and the presence of RF [7]. We conducted IgG profiling of human and rodent plasma on high density protein microarrays and subjected higher reactive differentially reactive antigens (DIRAGs) to pathway analysis aiming to elucidate the underlying processes (Figure 1)

Methods

Results

Conclusion