Macrophages are the main effector cells of innate immunity and are involved in inflammatory and anti-infective processes. They also have an essential role in maintaining tissue homeostasis, supporting tissue development, and repairing tissue damage. Until few years ago, it was believed that tissue macrophages derived from circulating blood monocytes, which terminally differentiated in the tissue and unable to proliferate. Recent evidence in the biology of tissue macrophages has uncovered a series of immune and ontogenic features that had been neglected for long, despite old observations. These include origin, heterogeneity, proliferative potential (or self-renewal), polarization, and memory. In recent years, the number of publications on tissue resident macrophages has grown rapidly, highlighting the renewed interest of the immunologists for these key players of innate immunity. This mini-review aims to summarizing the new current knowledge in macrophage immunobiology, in order to offer a clear and immediate overview of the field.
Biology ; Homeostasis ; Immunity, Innate ; Macrophages* ; Memory* ; Monocytes ; Population Characteristics

Objective:To study the effects of andrographolide on the expression of IL-18 related cytokines by peripheral blood monocytes.Methods:After treatment of andrographolide in different concentrations on LPS stimulated human peripheral blood mononuclear cells (PBMC) and LPS+IFN-γ/IL-4 activated magnetic bead-sorted monocytes (PBM),the transcription level of IL-18,IL-18BP,IL-18Rα and IL-18Rβ was detected by real-time RT-PCR;and secreted IL-18,IL-18BP and IL-1β,IL-1Rα by PBM was detected with ELISA.Results:Andrographolide regulated the transcription of IL-18 and IL-18BP in a dose-and time-dependent effect.Andrographolide up-regulated the transcription of IL-18BP in LPS stimulated PBMC,and increased the ratio of IL-18BP/IL-18.The ratio of IL-18BP/IL-18 rose from 9.60 to 214 in LPS+IFNγ activated PBM,and IL-1Rα/IL-1β declined from 9 200 to 6 520 in IL-4 activated PBM by andrographolide treatment.Conclusion:Andrographolide can regulate IL-18 related gene transcription and expression in activated peripheral blood monocytes,and inhibit the excessive expression of IL-18 during inflammation.