Impaired cytokine production and decreased TLR2-mediated signaling in mouse infant macrophages.

Infants are known to be more susceptible to pathogens. This might be due in part to the impaired function of macrophage. In the present study, we observed that macrophages from infant mice produced decreased levels of TNF-α and IL-6, but increased IL-10 after stimulation with toll-like receptor 2 (TLR2) agonist zymosan. Moreover, zymosan-stimulated activation of mitogen-activated protein kinase (MAPK) p38 and ERK1/2 was significantly reduced in mouse infant macrophages. These effects could be reversed by using MAPK modulators. The findings suggest that the impaired cytokine production and decreased TLR2-mediated signaling in infant macrophages may contribute to the susceptibility of infants to bacterial infection.