Interleukin-1β regulates Vero cell interleukin-1 receptor type I messenger ribonucleic acid expression

Embryos cocultured with Vero cells display enhanced development in vitro. This could be due to an interaction between the embryo and cellular layer mediated by paracrine cytokines. The interleukin-1 (IL-1) system is composed of two IL-1 agonists, IL-1 receptor antagonist (IL-1 ra), and two major IL-1 receptors (IL-1 R tl and tll). In this study, we measured Vero cell expression of IL-1 system mRNAs with reverse transcription polymerase chain reaction (RT-PCR) and validated the results with an immunohistochemistry study. RT-PCR revealed β-actin and IL-1R tI mRNA expression in Vero cell cocultures without detectable IL-1β and IL-1ra mRNA expression. To determine the effect of IL-1β on IL-1R tl mRNA expression in Vero cells, quantitative competitive PCR methodology was developed. A competitive cDNA fragment was coamplified as an internal standard with the target cDNA sequence of IL-1R tl, showing a 50% decrease in Vero cell IL-1R tl cDNA cultured in the presence of IL-1β (100 IU/ml) compared to control Vero cell cultures (62.5 fg vs. 125 fg). Down-regulaton of IL-1R tl mRNA by IL-1β is dose-dependent, with increasing concentrations (0-1000 IU/ml) of IL-1β producing progressive attenuation of IL-1 R tl expression. Treatment with anti-IL-1β antibody ablated the inhibitory effect of IL-1β (100 IU/ml) on IL-1R tl mRNA expression. Immunostaining confirmed the presence of IL-1R tl protein in Vero cells. These results demonstrate the presence of IL-1 R tl in Vero cell monolayers and regulaton of IL-1 R tl mRNA by IL-1β.