Alteration of plasma cytokines in patients with active epilepsy
Inflammation induced by innate immune response through cerebral resident cells (astrocytes, neurons, and microglia) contributes to the production of multiple cytokines, which may recruit cells (T lymphocyte and B lymphocyte) of the adaptive immune system and lead to secretion of more cytokines such as interferon gamma (IFN‐γ) and interleukin‐17 (IL‐17).3 Thus, inflammation response is enlarged and plays an important role in multiple CNS diseases including MS, stroke, and trauma.5 In experimental epilepsy model, many studies focus on immediate postictal changes in cytokines and cytokine mRNA. The results reveal a significant increase of pro‐inflammatory cytokines, such as IL‐1β, IL‐6, and TNF‐α, rapidly occur after induced status epilepticus (SE) or seizures in hippocampus and upregulation of inflammatory cytokine mRNA within a few hours after generalized seizures.7 Hippocampal IFN‐gamma (IFN‐γ) level is also significantly higher in fully kindled epileptic rats.10 These animal experiments suggest that innate and adaptive immune system is rapidly activated which leading to elevated cytokines in this period. However, data from clinical researches are not in line with animal experiments. Postictal concentration of IL‐1β after generalized tonic–clonic or complex partial seizures had no significant difference from baseline.11 Level of IL‐6 rapidly elevated in the plasma of epilepsy patients, especially in the TLE patients,7 and upregulation of IL‐6 was found to be positively correlated with the severity of the seizure.13
Few studies show solicitude for the interictal alteration of cytokines in epilepsy. Sinha et al. reported increased postictal serum cytokine levels in patients with several epilepsy syndromes, following decreased levels of TNF‐α, IL‐1β, IL‐6, IL‐2, IL‐4, and IFN‐γ in the seizure‐free state.14 Another study indicated that interictal IL‐6 concentration in peripheral blood elevated while TNF‐α and IL‐1β remain unchanged.15
Due to these ambiguities, the aim of this study was to evaluate postictal and interictal changes of IL‐1β, IL‐6, IL‐10, TNF‐α, IFN‐γ, and IL‐17A in peripheral blood of active epilepsy patients. In addition, we tried to identify whether alterative interictal cytokines correlate with seizure severity.