Life science
Medical & healthcare, Bioinformatics

Plasma cell-free DNA analysis clarifies novel mechanism ofautoimmune neurological disease
Department of Neurology, Graduate School of Medicine
Specially Appointed Lecturer Makoto Kinoshita

https://researchmap.jp/101101101101101

Professor Hideki Mochizuki

https://researchmap.jp/read0207787

Life science

Abstract
Fragments of nuclear DNA is released in biofluids as cell-free
DNA (cfDNA) by various types of cell death. In this project, we
identified the source of plasma cfDNA in the patients with neuromyelitis optica spectrum disorder (NMOSD) by investigating thecell type–specific DNA methylation patterns. NMOSD is an autoimmune disease of the central nervous system (CNS), characterized
by severe inflammation predominantly observed in the optic nerves
and the spinal cord. The primary source of plasma cfDNA in
NMOSD was revealed to be neutrophils. Further analysis showedthat plasma cfDNA derived from NMOSD enhance type1 interferon
expression in the peripheral blood mononuclear cell (PBMCs), thus
elucidating the novel role of neutrophils in establishing the foundation of NMOSD immune signature. Our bioinformatics approach toidentify the origin of biofluid cfDNA is a powerful method that canbe applied to various types of diseases, and is expected to clarify
novel pathogenic mechanisms.

▍ Background & Results
NMOSD is an autoimmune-mediated disease of CNS. Autoantibody targeted against aquaporin-4 (AQP4), water channels expressed on the endfeet of astrocytes, is the specific marker of thedisease. Although the pivotal role of anti-AQP4 antibody is well-appreciated in the pathogenesis of NMOSD, the immune signaturethat leads to the production of autoantibody in the patient withNMOSD remained elusive.
In this project, we identified the source of plasma cfDNA in
the patients with NMOSD by investigating the cell type–specificmethylation patterns. Bioinformatics approach showed that neutrophils are the major types of cells responsible for cfDNA release inNMOSD. Further in vitro studies showed that blood cfDNA induce
type1 interferon expression in PBMC, especially plasmacytoid dendritic cells, in coordination with LL-37. In addition, the transcriptome analysis of PBMC derived from NMOSD elucidated neutrophil
activation as the major pathway establishing the immune signatureof NMOSD. These results highlighted the previously unidentified
role of neutrophils in the pathogenesis of NMOSD, and showed
their pivotal capacity to induce type1 interferon production in thedisease.

Identification of the source of cell-free DNA by cell type-specific methylation
patterns

Activation of Type1-IFN pathway by neutrophil-derived cell-free DNA in NMOSD▍ Significance of the research and Future perspective
In this project, we elucidated a novel pathogenic mechanism ofNMOSD by identifying the cellular source of plasma cfDNA. Our
bioinformatics approach to clarify the origin of biofluid cfDNA is expected to reveal novel pathogenesis in various types of disease infuture studies.

P a t e n t
Tr e a t i s e

Murata, Hisashi; Kinoshita, Makoto; Yasumizu, Yoshiaki et al. Cell-Free DNA Derived From Neutrophils Triggers Type 1 Interferon Signature in Neuromyelitis
Optica Spectrum Disorder. Neurol Neuroimmunol Neuroinflamm 2022, 9: e1149. doi:10.1212/NXI.0000000000001149

URL
K e y w o r d cell-free DNA, autoimmune disease, bioinformatics, neurological disease