Understanding Complement-mediated Nervous System aging in Order to Develop Neurodegenerative Therapeutics

Aging is becoming one of the biggest burdens to the developed world, mainly due to it being linked to a variety of diseases from neurodegenerative disorders such as Alzheimer’s disease to cancer. It involves the dysregulation of virtually every biological process known, affecting every organ and tissue by distinct mechanisms, the nature of which is only now beginning to be truly understood. This is also true for memory loss, which is considered one of the most typical signs of old age. This is not surprising, given the still limited knowledge regarding how memories and thoughts are stored and utilised by the Central Nervous System (CNS). A potential hint, however, is the recent discovery that the complement system plays a role in synaptic pruning, which is essential for erasing unneeded memories. This is particularly intriguing given that the complement system is a branch of the innate immune system which has been documented as being overactive with aging. This review will thus cover what is currently known about the relationship between the immune system and aging and how the changes in the immune system with age affect the brain in an effort to direct further research. This topic has not been reviewed as a whole, which is why this paper aims to summarise the information on this topic whilst also elaborating on the gaps in research in order to develop potential therapies for neurodegeneration and immunosenescence.