Abstract

BACKGROUND: Osteoarticular tuberculosis is an osteolytic lesion caused by Mycobacterium tuberculosis (MTB). Inflammatory factors such as TNF-α play a critical role in anti-tuberculosis immunity by regulating osteoblast and osteoclast functions. Both TGF-β and IL-10 have immune suppression effects to downregulate secretion and release of inflammatory factors, such as TNF-α, that play roles in regulating osteoblast and osteoclast functions. This study thus investigated the effects of osteoclast with modified TGF-β and IL-10 gene expression on MTB-induced osteoclast formation and bone absorption.

MATERIAL AND METHODS: Bone marrow mononuclear cells were induced to differentiate into osteoblasts and osteoclasts in vitro to generate a co-culture system. MTB powder lysed by ultrasound (Mt sonicate) were added in gradients to observe osteoblast formation and osteoclast absorption. Cell apoptosis was measured by flow cytometry, while ELISA was used assess TNF-α, TGF-β, and IL-10. Viral vectors carrying TGF-β or IL-10 gene were used to transfect osteoclasts, followed by ELISA assay. Bone absorption and osteoblast apoptosis were compared among groups.

RESULTS: Mt sonicate significantly facilitated osteoclast formation and bone formation. It upregulated contents of TNF-α, TGF-β, and IL-10, induced osteoblast apoptosis, enhanced RANKL expression in osteoblasts, and decreased OPG expression. Overexpression of TGF-β and/or IL-10 significantly decreased its upregulation effect on TNF-α by Mt sonicate, and hindered Mt sonicate-induced osteoblast apoptosis, osteoclast formation, and bone absorption.

CONCLUSIONS: Overexpression of TGF-β and IL-10 significantly inhibits TMB-induced TNF-α synthesis and release, suppresses osteoblast apoptosis, and hinders osteoclast formation and bone absorption.

Keywords: Gene Expression Profiling, Receptors, Interleukin-10, Tuberculosis, Avian