Immune-Based Modulation of Adult Hippocampal Neurogenesis, Link to Systemic Th1/Th2 Balance

Fangfang Qi, Yucen Xia, Zejie Zuo, Yingying Wu, Junhua Yang, Xiao Wang and Zhibin Yao

The interaction between adaptive immune system and the Central Nervous System (CNS) has been extensively studied for decades. A series of researches have indicated that systemic T cells, particularly CD4+ T cells are involved in supporting fundamental processes of brain functional integrity, such as in the maintenance of brain plasticity including spatial learning and memory, and neurogenesis. Moreover, recent data from our laboratory indicate alteration of systemic T helper cell type 1 (Th1)/Th2 balance is tightly linked to hippocampal neurogenesis and working memory. In this review, we summarize current knowledge of the systemic Th1/Th2 balance, describe how this skewing appears to operate in hippocampal neurogenesis, and reinforce the theory of interaction mechanism of these two vital systems.