Background
Interleukin-34 (IL-34) is a recently discovered cytokine functionally overlapping macrophage colony stimulating factor (M-CSF), a mediator of inflammation and osteoclastogenesis in bone-degenerative diseases such as rheumatoid arthritis. The
Methods
IL-34 expression was evaluated in gingival fibroblasts by real time PCR following stimulation by TNF-α, IL-1β, and treatment with inhibitors of intracellular pathways. The formation of osteoclasts was evaluated by tartrate-resistant acid phosphatase (TRAP) staining of bone marrow macrophages treated with IL-34 or M-CSF in addition to receptor activator of nuclear factor kappa-B ligand (RANKL).
Results
IL-34 was expressed in gingival fibroblasts. The expression was enhanced by TNF-α and IL-1β, regulated by the transcription factor nuclear factor kappa B (NF-κΒ) and activation of c-Jun N-terminal kinase (JNK). Further, IL-34 supports RANKL-induced osteoclastogensis of bone marrow macrophages, independently of M-CSF. Summary: In