Cancer and Immunology-the Homeostasis Dance

The human body is made up of not only tissues and blood, but also microbiota on the surfaces of the skin, mucosal membrane of the intestine, urogenital, lungs, and mouth, to form ecological niches. Some of these niches have been well studied, while some are understudied, due to the unknown presence of these microbiota in such systems. The T cell response by the immune system is one step of the cancer-immunity cycle, that maintains the prevention of autoimmunity. Cancer cells have T cell inhibitory signals, including programmed death-ligand-1, which have been identified for the development of new immunotherapies that are specifically responsible for hindering immune effector inhibition, thereby reinvigorating, and enhancing pre-existing anticancer immune response. Previous activity in immune therapies has always considered suppressive factors in the tumour microenvironment without consideration to other factors such as the genetic basis of the immune system. Attention to the immune system has always been on the response to the pathogens, or the threatening foreign target, but not on the genes responsible for regulating the immune system. The immune system is a concert of interactions between existing microbes and host. One of the major tools of cellular interaction is epigenetics. Epigenetic information regulates differentiation and development, thus can impact on pathological condition. Therefore, it is vital to understand the resident parties (constituents) in an ecosystem, the basic system behind the ecosystem and epigenetics interaction within the ecosystem (microbes and host) is vital in cancer development and treatment.