Effects of ketogenic diet on helper T cells in patients with intractable epilepsy

Abstract

Objective To investigate the effects of ketogenic diet (KD) treatment on helper T cell subsets in children with intractable epilepsy (IP). Methods Thirty-five children with IP and eighteen age-matched healthy subjects were enrolled in this study. The percentages of CD3+ CD8-IFN-γ+ (Th1) cells, CD3+ CD8-IL-17A+ (Th17) cells and CD4+ CD25+ Foxp3+ (Treg) cells were analyzed by flow cytometry. Real-time PCR assay was performed to evaluate the expression of T-bet, ROR-γ, IFN-γ, IL-17A and peroxisome proliferator activated receptor γ (PPAR-γ) at mRNA level in CD4+ CD25-T cells and the transcriptional levels of Foxp3, GITR, CTLA-4 and PPAR-γ in CD4+ CD25+ T cells. The concentrations of cyclooxygenases-2 (COX-2) and prostaglandin F2a (PGF2α) in plasma samples were measured by enzyme-linked immunosorbent assay. The expression of IL-17A and IFN-γ in plasma samples were detected by using cytometric bead array (CBA). Results (1) The percentages of Treg cells in peripheral blood samples from patients with IP were lower than those in healthy subjects (P<0.05), which were significantly increased with the treatment of KD (P<0.05). The percentages of Th17 and Th1 cells in patients with IP were significantly higher than those in healthy children (P<0.05), but were remarkably decreased with the treatment of KD (P<0.05). Patients with IP showed decreased transcriptional levels of Foxp3, GITR and CTLA-4 in CD4+ CD25+ T cells as compared with healthy controls, but were up-regulated with the treatment of KD. The expression of transcription factors including T-bet, ROR-γ, IFN-γ and IL-17A in CD4+ CD25-T cells in patients with IP were higher than those in healthy subjects and were down-regulated after the treatment of KD (P<0.05). (2) The expression of PPAR-γ at mRNA level in CD4+ CD25- T and CD4+ CD25+ T cells were decreased in patients with IP as compared with those in heathy controls, but were increased after the treatment of KD (P<0.05). Correlation analysis showed that Treg cells had a positive correlation with PPAR-γ (r=0.61, P<0.05). However, the Th1 and Th17 cells were negatively correlated with PPAR-γ [Th1 (r=-0.54, P<0.05), Th17 (r=-0.64, P<0.05) ]. (3) The levels of IL-17A and IFN-γ in patients with IP were higher than those in healthy controls, but were decreased with KD treatment (P<0.05). The levels of COX-2 and PGF2α in plasma samples from patients with IP were higher than those in healthy controls (P<0.05). A negative correlation was observed between COX-2 and PPAR-γ (r=-0.571, P<0.05). Moreover, PGF2α and PPAR-γ had a negative correlation as well (r=-0.586, P<0.05). Conclusion The treatment of KD might enhance the expression of PPAR-γ through inhibiting the products of oxidative stress such as COX-2 and PGF2α, resulting in the rebalance of Th cell subsets and reduced expression of inflammatory cytokines. Key words: Ketogenic diet; Intractable epilepsy; Th cells; Peroxisome proliferator-activated receptor γ; Oxidative stress