CDB25:0003738 HP — TLR4
Experimentally validated in Human; Orthology-inferred in Mouse, Rat, Frog, Zebrafish, Macaque, Pig, Dog, Cow, Horse, Marmoset, Sheep
Title
Journal:; Year Published:
Abstract
Haptoglobin Acts as a TLR4 Ligand to Suppress Osteoclastogenesis via the TLR4-IFN-β Axis.
Journal of immunology, 2019; PubMed, Homo sapiens HP — Homo sapiens TLR4
ABSTRACT: Haptoglobin (Hp), a type of acute-phase protein, is known to have a systemic anti-inflammatory function and to modulate inflammation by directly affecting immune cells, such as T cells, dendritic cells, and macrophages. However, the effects of Hp on osteoclast differentiation are not well studied, even though osteoclast precursor cells belong to a macrophage-monocyte lineage. In this study, we found that the bone volume was reduced, and the number of osteoclasts was increased in Hp-deficient mice compared with wild-type mice. Moreover, our in vitro studies showed that Hp inhibits osteoclastogenesis by reducing the protein level of c-Fos at the early phase of osteoclast differentiation. We revealed that Hp-induced suppression of c-Fos was mediated by increased IFN-β levels. Furthermore, Hp stimulated IFN-β via a TLR4-dependent mechanism. These results demonstrate that Hp plays a protective role against excessive osteoclastogenesis via the Hp-TLR4-IFN-β axis.