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

ABSTRACT: To define the pathogenesis of bone marrow (BM) involvement in systemic lupus erythematosus (SLE).Tumor necrosis factor ? (TNF?) 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), TNF?(-/-) , Toll-like receptor-deficient (TLR-7(-/-) ), interferon (IFN)-?/?/? receptor-knockout (IFNAR(-/-) ), and B cell-deficient (?mt) mice treated with pristane. Flow cytometry was used to examine TNF? production (by intracellular staining) and plasma cell/plasmablast development. CXCL12 expression was determined by quantitative polymerase chain reaction.BM from SLE patients exhibited striking death of niche and hematopoietic cells associated with TNF? overproduction. BM from mice with a type I IFN-mediated lupus syndrome induced by pristane showed similar abnormalities. TNF? was produced mainly by BM neutrophils, many with phagocytosed nuclear material (lupus erythematosus cells). TNF? production was abolished in pristane-treated TLR-7(-/-) and ?mt mice but was restored in ?mt 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 TNF?(-/-) 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 TNF?(-/-) mice.Although autoantibodies and glomerulonephritis are type I IFN dependent, lupus-associated BM abnormalities were TLR-7 and TNF? 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 TNF? production mediating glomerulonephritis and hematologic involvement, respectively.

SUBMITTER: Zhuang H 

PROVIDER: S-EPMC3990233 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature