The CNS Innate Immune System and the Emerging Roles of the Neuroimmune Regulators (NIRegs) in Response to Infection, Neoplasia and Neurodegeneration

The mammalian CNS relies upon the ancient, innate immune system, to provide defence against attack by pathogens (virus, bacteria, fungi and parasites) and the clearance of both neurotoxic proteins and apoptotic cells. The main function(s) of the CNS innate immune system can be summarised as the detection of “non self”(pathogens) and “ altered self “ (neurotoxic proteins and apoptotic cells), with their subsequent clearance, designed to facilitate tissue repair and rapid return to normal function. The failure to express an effective protective response to detect and remove a pathogen (non –self) prolongs the innate immune response and this is associated with autoimmunity, chronic inflammatory diseases (Multiple sclerosis) and neuro degeneration (Alzheimer’s and Prion disease) (Hauwel et al., 2005 Griffiths et al., 2009). The failure to detect and clear apoptotic cells results in their accumulation and subsequent release of neurotoxic proteins and enzymes, contributing to excessive tissue damage (Griffiths et al., 2009).