Inflammatory response of macrophages in infection

BACKGROUND: Macrophages are widely-distributed innate immune cells playing diverse roles in various physiological and pathological processes. The primary function of macrophages is to phagocytize and clear invading pathogens. DATA SOURCES: A systematic search of PubMed was performed to identify relevant studies in English language literature using the key words such as macrophage and inflammation. A total of 122 articles related to inflammatory response of macrophages in infection were systematically reviewed. RESULTS: The inflammatory responses of macrophages triggered by infection comprise four interrelated phases: recognition of pathogen-associated molecular patterns by pattern-recognition receptors expressed on/in macrophages; enrichment of quantity of macrophages in local infected tissue by recruitment of circulating monocytes and/or in situ proliferation; macrophage-mediation of microbicidal activity and conversion to anti-inflammatory phenotype to terminate anti-infectious response and to promote tissue repair. Complicated regulation of macrophage activation at molecular level recognized in the past decade is also reviewed, including intracellular multiple signaling molecules, membrane molecules, microRNAs and even epigenetic-associated molecules. CONCLUSION: The inflammatory response of macrophages in infection is an orderly and complicated process under elaborate regulation at molecular level.