Interleukin-1 β Regulates Vero Cell Interleukin-1 Receptor Type I Messenger Ribonucleic Acid Expression1

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-1ra), and two major IL-1 receptors (IL-1R tII). 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 beta-actin and IL-1R tI mRNA expression in Vero cell cocultures without detectable IL-1 beta and IL-1ra mRNA expression. To determine the effect of IL-1 beta on IL-1R tI 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 tI, showing a 50% decrease in Vero cell IL-1R tI cDNA cultured in the presence of IL-1 beta (100 IU/mI) compared to control Vero cell cultures (62.5 fg vs. 125 fg). Down-regulation of IL-1R tI mRNA by IL-1 beta is dose-dependent, with increasing concentrations (0-1000) IU/ml) of IL-1 beta producing progressive attenuation of IL-1R tI expression. Treatment with anti-IL-1 beta antibody ablate the inhibitory effect of IL-1 beta (100 IU/ml) on IL-1R tI mRNA expression. Immunostaining confirmed the presence of IL-1r tI protein in Vero cells. These results demonstrate the presence of IL-1 R tI in Vero cell monolayers and regulation of Il-1R tI mRNA by IL-1 beta.