Interleukin-1β enhances the effect of serum deprivation on rat annular cell apoptosis

Abstract

Excessive apoptosis of disc cells is believed to play an important role in intervertebral disc (IVD) degeneration. It has been shown that interleukin-1beta (IL-1beta) is involved in the failure of disc matrix by suppressing the synthesis of matrix components and stimulating the expression of matrix metalloproteinases. However, whether IL-1beta induces disc cell apoptosis is still unclear. The objective of this study was to investigate the effect of IL-1beta on the apoptosis of rat annular cells cultured with or without serum supplement. First-passage rat annular cells were cultured with 0% or 10% fetal bovine serum (FBS) supplement and stimulated with 0, 10, 20 or 50 ng/ml IL-1beta for 12, 24 or 48 h. Apoptotic incidences were quantified by flow cytometry, morphologic changes in apoptotic cells were visualized by Hoechst 33258 staining and phase-contrast microscopy, and caspase-3 activity was also determined. When rat annular cells were cultured with 10% FBS supplement, no significant changes in apoptotic incidences, apoptotic morphology and caspase-3 activity were observed even when cells were stimulated with 50 ng/ml IL-1beta for 48 h. In contrast, serum deprivation for 24 h led to an increase in apoptotic incidences, the number of apoptotic nuclei and caspase-3 activity, and IL-1beta significantly increased the effects of serum deprivation in a dose-dependent manner. Our results indicate that IL-1beta alone is not a sufficient stimulus to induce disc cell apoptosis and that in order to suppress disc cell apoptosis, improving the nutrient supply to the disc may be more effective than antagonizing the adverse effects of IL-1beta.

Both endoplasmic reticulum and mitochondria are involved in disc cell apoptosis and intervertebral disc degeneration in rats

“…Our established method for isolation and primary culture of rat annular cells (Zhao et al 2007) was employed, and first-passage cells maintained in a monolayer were used throughout the in vitro experiments.…”

“…1 Cross-talk between mitochondria and ER in NO-induced apoptosis. Contents shown in italic type within the diagram were studied Pharmingen), as described previously (Zhao et al 2007). …”

“…Among many genetic and environmental factors that may contribute to the development of IVDD, disc cell death through apoptosis appears to be a major component (Ariga et al 2001(Ariga et al , 2003Court et al 2001;Gruber and Hanley 1998;Kohyama et al 2000;Kroeber et al 2002;Lotz and Chin 2000;Lotz et al 1998;Park et al 2001aPark et al ,b, 2005Park et al , 2006Rannou et al 2004;Walsh and Lotz 2004;Wang et al 2006a;Zhao et al 2006Zhao et al , 2007, but the signal transduction pathways involved in disc cell apoptosis have not been fully understood.…”

Aging and degeneration of the intervertebral disc: review of basic science

“…46 (Table 1) Although the means (intrinsic or extrinsic to the disc environment) that lead to deregulation in the production of IL-1β and TNF-α have not yet been elucidated, these are known to be related to the increase of matrix degrading enzymes, abnormal synthesis of aggrecan and type II collagen, besides its substitution by type I, angiogenesis, axonogenesis and apoptosis of IVD cells. 19,[50][51][52][53] …”

Serum deprivation induces apoptotic cell death in the ThESC cell line

“…Serum also enables the maintenance of optimal pH and the elimination of the toxic products from the medium (9). Serum deprivation is one of many methods used to induce programmed cell death, or apoptosis (17,18,19). Previous research has demonstrated that cells in serum-deprived media undergo numerous changes that lead to apoptosis.…”