Immunotherapy has advantages including few side effects and low probability of abuse by patients. Recently, functional materials with immunomodulatory functions, which act through reduction of free radicals, have been developed for cancer and anti-inflammatory therapy. However, the therapeutic application of natural functional materials involves a complex mechanism along with various organic factors. These substances, including polysaccharides and triterpenoids, have immunomodulatory effects. However, to our knowledge, the mechanism underlying the action of such substances in the physiological immunity of animals remains unclear. Immune cells, particularly macrophages, are crucial in the modulation of immune response. Macrophages polarise into two types, namely, M1 and M2, from the M0 form, based on the physiological microenvironment factors. M1 macrophages have functions in pathogen elimination through phagocytosis, oxidative damage, and complement system activation. M2 macrophages are involved in tissue recovery and tumour tissues containing ample M2 macrophages that release growth factors, which promote angiogenesis. In this study, we focus on the immunomodulation of the macrophage to further understand the effects of the physiological microenvironment factors on macrophage polarisation.
Part of the book: Cells of the Immune System
The inflammation response requires the cooperation of macrophages with immune cell function and active factors, such as cytokines and chemokines. Through this response, these factors are involved in the immune response to affect physiological activities. Macrophages can be categorized into two types: ‘M1’ and ‘M2’. M1 macrophages destroy the pathogen through phagocytosis activation, ROS production, and antigen-presenting, among other functions. M2 macrophages release cellular factors for tissue recovery, growth, and angiogenesis. Studies have determined that tumour tissue presents with numerous macrophages, termed tumour-associated macrophages. Tumour cells and peripheral stromal cells stimulate the tumour associated with macrophages (M2) to produce factors that regulate angiogenesis. Modulating the balance of the M1 and M2 function has already gained interest as a potentially valuable immune disease therapy. However, applications of the immunotherapy in clinical treatments are still not clear with regard to the cellular working mechanism. Therefore, we summarized the functions of common biomaterials involved in the modulation of the macrophage.
Part of the book: Macrophages