Usefulness of Monocytes/macrophages Activated With Low-dose Lipopolysaccharide in Tumor Tissue and Adipose Tissue of Obesity

Chronic inflammation is involved in the development of cancer, lifestyle-related diseases, and autoimmune diseases. It also influences the severity of these diseases. Macrophages that accumulate in tumor tissues and adipose tissues of obesity have been shown to increase expression of inflammatory cytokines, thereby inducing inflammatory changes in these tissues. The macrophage phenotype is believed to be important in mediating inflammatory changes in tissues. Recently, monocytes/macrophages activated with low-dose lipopolysaccharide (LPS) were demonstrated to suppress increased expression of monocyte chemotactic protein (MCP)-1 and inflammatory cytokines (interleukin (IL)-1 beta, IL-8, and tumor necrosis factor (TNF)-alpha). By suppressing the increased expression of chemotaxis-related and inflammation-related factors, monocytes/macrophages activated with low-dose LPS are considered to suppress the migration of macrophages into tissues and to regulate inflammatory changes in these tissues, respectively. The effects of macrophages activated with low-dose LPS were different from those of macrophages activated with high-dose LPS. In this review, we discuss the usefulness of monocytes/macrophages activation by low-dose LPS.