Th17 cells and IL-17A in traumatic brain injury: mechanisms and therapeutic perspectives.

Traumatic brain injury (TBI) triggers a complex cascade of immune responses that extend beyond the central nervous system and contribute to secondary neuropathology. Increasing evidence implicates T helper 17 cells (Th17) and their signature cytokine interleukin-17A (IL-17A) in post-traumatic neuroinflammatory processes, including blood-brain barrier (BBB) disruption and neuroimmune interactions. This review synthesizes current evidence on the context-dependent roles of Th17 cells and IL-17A in TBI, with a focus on underlying molecular mechanisms, cellular targets, and the limitations of existing experimental data. We further discuss emerging therapeutic strategies aimed at modulating the Th17/IL-17A axis, as well as recent observations linking IL-17A signaling to neural plasticity and functional outcomes. Taken together, these findings highlight both the translational challenges and conceptual opportunities associated with targeting Th17/IL-17A-related pathways following TBI.