Curcumin reduces brain-infiltrating T lymphocytes after intracerebral hemorrhage in mice

T lymphocytes contribute to inflammation, thereby exacerbating neuronal injury after cerebral ischemia. An increasing amount of evidence indicates that inflammation is a key contributor to intracerebral hemorrhage (ICH)-induced secondary brain injury. Curcumin, a low-molecular-weight curry spice that is derived from the Curcuma longa plant, suppresses T lymphocyte proliferation and migration. Based on these findings, we investigated whether treatment with curcumin would reduce the number of cerebral T lymphocytes in mice with experimentally induced ICH. We found that a large number of T lymphocytes infiltrated the brain at 3days post-ICH. Curcumin significantly improved neurological scores and reduced brain edema in mice with ICH, consistent with a role in reducing neuroinflammation and neurovascular injury. Using flow cytometry, we observed significantly fewer T lymphocytes in brain samples obtained from the curcumin-treated group than in samples obtained from the vehicle-treated group. Moreover, Western blot analysis and immunostaining indicated that treatment with curcumin significantly reduced the expression of a vascular cell adhesion molecule-1 (VCAM-1), interferon-γ (INF-γ) and interleukin-17 (IL-17) in the mouse brain at 72h post-ICH. Our results suggest that administering curcumin may alleviate cerebral inflammation resulting from ICH, at least in part by reducing the infiltration of T lymphocytes into the brain. Therefore, preventing T lymphocytes from infiltrating the brain may become a new strategy for treating clinical ICH.