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  • PMID: 24022519 was deleted because it is a duplicate of PMID: 24449581
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Arthritis Rheumatol. 2014 Jan;66(1):140-51. doi: 10.1002/art.38189.

Toll-like receptor 7-stimulated tumor necrosis factor α causes bone marrow damage in systemic lupus erythematosus.

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  • 1University of Florida, Gainesville.

Abstract

OBJECTIVE:

To define the pathogenesis of bone marrow (BM) involvement in systemic lupus erythematosus (SLE).

METHODS:

Tumor necrosis factor α (TNFα) levels, cell death, and cellular damage in BM from SLE patients, controls, and mice with pristane-induced lupus were analyzed using a morphometric technique and immunohistochemistry. The pathogenesis of BM abnormalities was studied in wild-type (WT), TNFα(-/-) , Toll-like receptor-deficient (TLR-7(-/-) ), interferon (IFN)-α/β/ω receptor-knockout (IFNAR(-/-) ), and B cell-deficient (μmt) mice treated with pristane. Flow cytometry was used to examine TNFα production (by intracellular staining) and plasma cell/plasmablast development. CXCL12 expression was determined by quantitative polymerase chain reaction.

RESULTS:

BM from SLE patients exhibited striking death of niche and hematopoietic cells associated with TNFα overproduction. BM from mice with a type I IFN-mediated lupus syndrome induced by pristane showed similar abnormalities. TNFα was produced mainly by BM neutrophils, many with phagocytosed nuclear material (lupus erythematosus cells). TNFα production was abolished in pristane-treated TLR-7(-/-) and μmt mice but was restored in μmt mice by infusing normal plasma. Pristane-treated WT and IFNAR(-/-) mice developed anemia, BM hypocellularity, and extramedullary hematopoiesis, which were absent in TLR-7(-/-) and TNFα(-/-) mice. Additionally, the expression of CXCL12, which is produced by stromal cells and mediates homing of hematopoietic cells and plasmablasts, was decreased in BM from pristane-treated WT mice but was normal in BM from pristane-treated TNFα(-/-) mice.

CONCLUSION:

Although autoantibodies and glomerulonephritis are type I IFN dependent, lupus-associated BM abnormalities were TLR-7 and TNFα driven but type I IFN independent, suggesting that lupus is a disorder of innate immunity in which TLR-7 activation by phagocytosed nuclei causes relentless type I IFN and TNFα production mediating glomerulonephritis and hematologic involvement, respectively.

Copyright © 2014 by the American College of Rheumatology.

PMID:
24449581
[PubMed - indexed for MEDLINE]
PMCID:
PMC3990233
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