Clonal evolution and antigen recognition of anti-nuclear antibodies in acute systemic lupus erythematosus

Shuhei Sakakibara,Junichi Takagi,Daron M Standley,Jun Katayama,Takao Arimori,Hitoshi Kikutani,Daisuke Motooka,Kazuya Takeda,Songling Li,Kazuo Yamashita,Shota Nakamura,Masashi Narazaki,Marwa Ali El Hussien,Toshio Tanaka,Hideyuki Jinzai

doi:10.1038/s41598-017-16681-y

Abstract

The evolutional process of disease-associated autoantibodies in systemic lupus erythematosus (SLE) remains to be established. Here we show intraclonal diversification and affinity maturation of anti-nuclear antibody (ANA)-producing B cells in SLE. We identified a panel of monoclonal ANAs recognizing nuclear antigens, such as double-stranded DNA (dsDNA) and ribonucleoproteins (RNPs) from acute SLE subjects. These ANAs had relatively few, but nonetheless critical mutations. High-throughput immunoglobulin sequencing of blood lymphocytes disclosed the existence of sizable ANA lineages shearing critical mutations intraclonally. We further focused on anti-DNA antibodies, which are capable to bind to both single-stranded (ss) and dsDNA at high affinity. Crystal structure and biochemical analysis confirmed a direct role of the mutations in the acquisition of DNA reactivity and also revealed that these anti-DNA antibodies recognized an unpaired region within DNA duplex. Our study unveils the unique properties of high-affinity anti-DNA antibodies that are generated through antigen-driven affinity maturation in acute phase of SLE.

Highlights

The evolutional process of disease-associated autoantibodies in systemic lupus erythematosus (SLE) remains to be established
Previous genetic analysis of murine monoclonal anti-double-stranded DNA (dsDNA) antibodies revealed a high frequency of basic amino acids in the complementarity-determining regions (CDRs), inferring that they contribute to electrostatic interactions with the DNA backbone[5]
The isolated antinuclear antibody (ANA) clones represented ~6% of the PB-derived monoclonal antibodies (mAbs) isolated from acute patients, but not from patients in remission or healthy donors (Fig. 1C), which was consistent with serum ANA titers of our subjects (Supplementary Fig. 1)

Summary

Introduction

The evolutional process of disease-associated autoantibodies in systemic lupus erythematosus (SLE) remains to be established. Because unmutated germline (GL) antibodies of selected ANA clones showed no reactivity or reduced self-reactivity in ELISA and anti-nuclear reactivity in IFA (Fig. 2B), the self-reactivity of most ANAs was dependent on somatically mutated residues, the numbers of VH and VL mutations of these clones were lower than those of mAbs derived from patients in remission and healthy donors.

Results

Conclusion