Macrophage Polarization in Inflammatory Diseases

Liu, Yan-Cun; Zou, Xian-Biao; Chai, Yan-Fen; Yao, Yong-Ming

Macrophage polarization is involved in the pathogenesis of severe sepsis, which represents an uncontrolled inflammatory response caused by infection or acute insults. Clinical or laboratory evidence for sepsis being an immunosuppressive disorder has been proposed by Hotchkiss [87] : apoptosis of the immune cells, relative increase in regulatory T cells [88] as well as myeloid derived suppressor cells [89] , thereby weakening the defense to pathogens. Subsequently a secondary infection occurs which acting as the leading cause of death in patients with severe sepsis or septic shock. As a kind of fugitive cells which change their phenotypes in the various microenvironments, macrophages probably participate in the development of immunosuppressive state in septic response by polarizing to an M2 phenotype. Porta and colleagues found that LPS-tolerant macrophages shared the same characters with M2 macrophages, and p50 subunit of NF-κB was the key regulator to the process [26] . Therefore, uncovering the mechanisms in the polarization of macrophages in different stages of sepsis and regulating the balance of it may hold great promise for the treatment of septic complications.