B Lymphocyte signaling established by the CD19/CD22 loop regulates autoimmunity in the tight-skin mouse.

Published

Journal Article

Systemic sclerosis (SSc) is characterized by fibrosis and autoimmmunity. Peripheral blood B cells from SSc patients specifically overexpress CD19, a critical cell-surface signal transduction molecule in B cells. CD19 deficiency in B cells also attenuates skin fibrosis in the tight-skin (TSK/+) mouse, a genetic model for SSc. Herein we analyzed two transgenic mouse lines that overexpress CD19. Remarkably, 20% increase of CD19 expression in mice spontaneously induced SSc-specific anti-DNA topoisomerase I (topo I) antibody (Ab) production, which was further augmented by 200% overexpression. In TSK/+ mice overexpressing CD19, skin thickness did not increase, although anti-topo I Ab levels were significantly augmented, indicating that abnormal CD19 signaling influences autoimmunity in TSK/+ mice and also that anti-topo I Ab does not have a pathogenic role. The molecular mechanisms for abnormal CD19 signaling were further assessed. B-cell antigen receptor crosslinking induced exaggerated calcium responses and augmented activation of extracellular signal-regulated kinase in TSK/+ B cells. CD22 function was specifically impaired in TSK/+ B cells. Consistently, CD19, a major target of CD22-negative regulation, was hyperphosphorylated in TSK/+ B cells. These findings indicate that reduced inhibitory signal provided by CD22 results in abnormal activation of signaling pathways including CD19 in TSK/+ mice and also suggest that this disrupted B cell signaling contribute to specific autoantibody production.

Full Text

Duke Authors

Cited Authors

  • Asano, N; Fujimoto, M; Yazawa, N; Shirasawa, S; Hasegawa, M; Okochi, H; Tamaki, K; Tedder, TF; Sato, S

Published Date

  • August 2004

Published In

Volume / Issue

  • 165 / 2

Start / End Page

  • 641 - 650

PubMed ID

  • 15277237

Pubmed Central ID

  • 15277237

International Standard Serial Number (ISSN)

  • 0002-9440

Digital Object Identifier (DOI)

  • 10.1016/S0002-9440(10)63328-7

Language

  • eng

Conference Location

  • United States