Effect of IL-34 on Macrophage Polarization

A cytokine recently found to play a role in monocyte survival has been termed interleukin 34 (IL-34). This cytokine plays a significant role in various physiological processes, including the regulation of cytokine and chemokine expression, differentiation of immune cells, and cell proliferation. In pathological conditions, IL-34 may mirror the pathophysiology of the disease involved, and simultaneously promote the growth and survival of myeloid cells, thereby maintaining homeostasis in the body. Increased levels of IL-34 have been shown in inflammation, autoimmune diseases, infections, and cancer. However, some studies reported that decreased levels IL-34 can be associated with several conditions such as neurological diseases.IL-34 macrophage phenotype is controlled with an immunosuppressive activity. Macrophages are heterogeneous both in function and phenotype. Depending on its biological characteristics and activity on macrophage polarization, IL-34 has been believed to have a therapeutic potential in the treatment of some diseases. The aim of this review is to discuss the role of IL-34 on macrophage polarization.