Mannose Receptor Ligands Regulate the Gene Expression of Toll-like Receptors in Chicken Monocytes

Abstract

Pattern recognition receptors play an important role in distinguishing foreign organisms and triggering host defense responses. In this study, we present evidence for differential immune responses in chicken monocytes exposed to the mannose receptor (MR) ligands mannan and horseradish peroxidase (HRP). In our study, mannan significantly up-regulated the expression of the MR gene at a high concentration of 200 μg/ml, but HRP did not. In stimulation experiments, neither mannan nor HRP induced nitric oxide (NO) production or stimulated cytokine (IL-1β, IL-6, and IL-10) gene expression. A concentration of 200 μg/ml mannan induced a significant increase in Toll-like receptor 2 (TLR2) gene expression. The gene expression of TLR1 and 3 was significantly up-regulated by different HRP concentrations. In contrast to TLR1 and 3, TLR4 exhibited a significant decrease in gene expression in a dose-dependent manner. These results may suggest that MR ligands affect the innate immune response of TLRs in chicken monocytes.