Loss of Neuronal Phenotype and Neurodegeneration: Effects of T Lymphocytes and Brain Interleukin-2.

Loss of neuronal phenotype and reversal of neuronal atrophy have been demonstrated in different models of central nervous system (CNS) injury. These processes may be generalizable to different types of brain neurons and circuitry. The idea that some injured neurons may lose their phenotype and/or atrophy with the potential to rejuvenate is a remarkable and potentially promising form of neuronal plasticity that is not well understood. In this paper, we present some of our laboratory's basic neuroimmunology research showing that peripheral T cells entering the CNS, and brain-derived interleukin-2 (IL-2), play significant roles in these intriguing processes. Our findings suggest, for example, that T cell immunosenesence could be involved in related processes of brain aging and contribute to neurodegenerative disease. Neuroimmunological approaches may provide new insights into yet undiscovered factors and brain mechanisms that regulate changes in neuronal integrity associated with aging and disease. Such findings could have important implications for discovering more effective strategies for treating patients with neurotrauma and neurodegenerative diseases (e.g., Alzheimer's disease).