Poststroke neuropsychiatric symptoms: relationships with IL-17 and oxidative stress

Stroke variably activates interleukin- (IL-) 17 expression, reduces regulatory T cells, and induces oxidative stress, which may support neurodegeneration. Ischemic stroke patients were screened for depressive symptoms (Center for Epidemiological Studies Depression (CES-D)) and cognitive status (Mini Mental State Examination). Proinflammatory cytokines (IL-17, IL-23, and interferon- [IFN-] γ), anti-inflammatory cytokine IL-10, and lipid hydroperoxide (LPH), a measure of oxidative stress, were assayed from fasting serum. Of 47 subjects (age 71.8 ± 14.4 years, 36% female), 19 had depressive symptoms (CES-D ≥ 16), which was associated with poorer cognitive status (F 1,46 = 8.44, P = 0.006). IL-17 concentrations did not differ between subjects with and without depressive symptoms (F 1,46 = 8.44, P = 0.572); however, IL-17 was associated with poorer cognitive status in subjects with depressive symptoms (F 1,46 = 9.29, P = 0.004). In those subjects with depressive symptoms, IL-17 was associated with higher LPH (ρ = 0.518, P = 0.023) and lower IL-10 (ρ = -0.484, P = 0.036), but not in those without. In conclusion, poststroke depressive symptoms may be associated with cognitive vulnerability to IL-17 related pathways, involving an imbalance between proinflammatory and anti-inflammatory activity and increased oxidative stress.