Autonomous or Integrated Immune System is Right for Biology

Abstract

Several authors professed in favor of an autonomous Immune System, which is capable of defending the host. This argument is debated here at length. The existence of the Neuroimmune Supersystem, where immune participation is obligatory, mitigate autonomy. Also, the immune system is involved in physiology: it regulates reproduction, menstrual cycle, neonatal development, brain development and function, exerts neuroprotection, sleep, pain, stress, ageing, and glucose homeostasis are all regulated by immune mechanisms. Recently it has been proposed that gut microbiota affects brain function. Abnormal microbes led to disease, when normal bacteria were given, the disease subsided. What is the meaning of this observation? Would the brain notice the bacteria in the gut? Yes indeed, brain cells and the associated nerves express toll-like receptors (TLR) and for this reason will directly sense intestinal bacteria. We do not know what are the consequences of such sensations? The immune system is also stimulated by gut bacteria. The immune system owes its existence to this stimulus. Would the immune system communicate this event to the brain? Most certainly! Finally mucosal epithelial cells, which represent an army of effector cells, also express TLR. These mucosal cells have tremendous value in host defense. They become activated, defend, and produce cytokines and chemokines, through which they communicate with the entire Neuroimmune Supersytem. We conclude that the entire Neuroimmune Supesystem is involved in the regulation of intestinal microbes. This is most powerful and very effective regulation indeed.