IL4 and obesity due to melanocortin 4 receptor deficiency: The polarization of macrophages is involved in the regulation of various disease processes, such as immune neuritis, inflammatory bowel disease (Harusato et al., 2013), diabetes and obesity (Feng et al., 2011), rheumatoid arthritis (Wang et al., 2017), etc. Macrophage polarization is induced by LPS to M1-type or by IL-4 to M2-type macrophages (Kimbrough et al., 2018).