engleski

Lipopolysaccharide injection suppresses osteoblastogenesis but stimulates osteoclastogenesis from mouse bone marrow cells

Lipopolysaccharide (LPS) from gram-negative bacteria may cause chronic inflammation and subsequent bone loss, and has been involved in the pathogenesis of several bacterially induced bone disseases. LPS strongly stimulates osteoclast formation and induces production of many local pro-inflammatory factors. The aim of our study was to investigate the effects of LPS on bone cell differentiation in the bone marrow microinvironment. C57BL/6 mice were injected intraperitonealy once a week during 4 weeks in a dose of 5 µ ; g and 20 µ ; g LPS/g. After 5 weeks, splenocytes from these mice were stimulated by mitogen Concanavalin A (ConA ; 10µ ; g/mL ) or LPS (25µ ; g/mL) for 4 days in culture followd by MTT cell proliferation assay. Bone marrow cells were cultured under conditions stimulating for osteoblastogenic differentiation or osteoclastogenic differentiation. Osteoclast-like cells were identified as tartarat-resistant acid phosphatase (TRAP)-positive multinucleated cells. Osteoblast colonies were detected as alkaline phosphatase-positive colony-forming units. MTT proliferation assay showed a dose-dependent stimulation of splenocyte proliferation after LPS in vivo treatment, which further increased upon restimulation in vitro with LPS or ConA. LPS-stimulation significantly suppressed osteoblast differentiation but stimulated osteoclast differentiation from bone marrow cells of LPS-injected mice. Goldner-trichrome staining of bone slides prepared from LPS-injected mice showed clearly detectable regions of ablated resident bone marrow cells accompanied with osteoinduction. Our preliminary results indicate that LPS-injection in vivo induced increase in osteoclast differentiation and inhibition in osteoblast differentiation from bone marrow cells ex vivo. In some mice, LPS caused significant dose-dependent ablation of resident bone marrow cells but also induced bone formation. Our further aim is to investigate intracellular mechanisms by which LPS affects bone cell differentiation.

osteoblastogenesis; osteoclastogenesis; lipopolysaccharide

nije evidentirano