IL-1α affects mineralized nodule formation by rat osteoblasts

Abstract

The present study was conducted to determine the effect of the inflammatory mediator interleukin 1α (IL-1α) on osteogenesis using rat osteoblasts. We examined the effect of IL-1α on cell proliferation, alkaline phosphatase (ALPase) activity, mineralized nodule formation, and the expression of extracellular matrix proteins in rat osteosarcoma cell lines. The cells were cultured with α-minimum essential medium containing 10% fetal bovine serum with and without 0, 1, 10, and 100 units/ml of IL-1α for up to 14 days. The mineralized nodule formation was examined by alizarin red staining, and the calcium content in mineralized nodules was determined using a Calcium C-Test kit. The expression of extracellular matrix proteins was estimated by determining levels of mRNAs using the semiquantitative reverse transcription-polymerase chain reaction. The mineralized nodule formation and the calcium content in mineralized nodules were remarkably suppressed by IL-1α after 5 days of culture. The ALPase activity decreased in a dose-dependent manner in the presence of IL-1α after 7 days of culture. The expression of type I collagen was decreased after 3 days of culture with IL-1α. The expression of bone sialoprotein was slightly decreased at days 3 and 5, and the expression of osteopontin was increased at days 3, 5, and 7 of culture with IL-1α. These results suggest that IL-1α suppresses osteogenesis through a decrease in ALPase and type I collagen production by osteoblasts.