T Cells and Subsets in Neuropathic Pain

Neuropathic pain (NP) is caused by lesions in the somatosensory nervous system and greatly affects the quality of life. Immune infiltration is a crucial factor in NP’s initiation, maintenance, resolution, and chronicity. Among the resident immune glial cells and infiltrated peripheral immune cells, T cells are the key components in NP, as they participate in almost every stage of the pain transmission process. T cells enter the nervous system days after nerve injury and can be detected months later. T cells consist of several subsets, including CD4+ (Th1, Th2, Th17), CD8+, and regulatory T cells (Tregs). Each of these subsets possesses unique characteristics in regulating the immune response in NP, which could enhance or attenuate the immune response. T cells can release and be affected by a series of chemokines and cytokines, which further create a certain immune response that either is stable or switches to another state. T cells directly or indirectly interact with neurons, glial cells, and other immune cells. Further investigation could improve our understanding of the mechanism of T-cell regulation and identify potential therapeutics of NP using the properties of T cells.