Notch Signaling Regulates Circulating T Helper 22 Cells in Patients with Chronic Hepatitis C

Notch signaling enhanced the response of interleukin (IL)-22-producing CD4⁺ T cells that were defined as T helper 22 (Th22) cells, and Notch-aryl hydrocarbon receptor (AhR)-IL-22 axis fine-tuned inflammatory response. Previous studies have demonstrated that both Notch signaling and Th22 cells took part in the pathogenesis of chronic hepatitis C virus (HCV) infection. Thus, in this study, we aimed at examining the regulatory role of Notch signaling in Th22 cells in HCV infection. A total of 59 patients with chronic hepatitis C and 22 normal controls (NCs) were enrolled in this study. The percentage of Th22 cells and mRNA expression of related transcriptional factors and cytokines were analyzed in response to γ-secretase inhibitor. Th22 cell frequency was significantly elevated in chronic hepatitis C in comparison with that in NCs. Inhibition of Notch signaling downregulated HCV-specific Th22 cells and IL-22 production, which was accompanied by the reduction of AhR and modulatory cytokines (IL-6 and tumor necrosis factor-α). Moreover, the suppression of Notch signaling also decreased the IL-22-mediated antimicrobial response in both normal and HCV-infected HepG2 cells/Huh7.5 cells. This process was also accompanied by the depression of signal transducers and activators of transcription 3 signaling. In conclusion, the current results suggested that Notch signaling acted as a critical pathway in determining the response to IL-22 in chronic hepatitis C. Thus, Notch-Th22 axis might be considered a new therapeutic target for HCV-infected patients.