Pivotal Roles of T-Helper 17-Related Cytokines, IL-17, IL-22, and IL-23, in Inflammatory Diseases

Figure 3

Schematic diagram of the role of activated Th17 cells during Con A-induced hepatitis. Con A injection induces IL-23 expression from Kupffer cells (also inducing IL-12, IL-6, TNF-α, and other cytokines) in the liver, then activates Notch signaling in activated Th17 cells (and other types of T cells). AHR-dependent production of IL-22 is pivotal for protection, and RORγt-dependent production of IL-17 is critical for pathogenesis. The IL-17/IL-17R signaling pathway also exacerbates hepatitis by inducing TNF-α and IL-6. Con A: Concanavalin A; AHR: aryl hydrocarbon receptor; RORγt: retinoic acid-related orphan receptor γt; TLR: toll-like receptor; GSI: γ-secretase inhibitor; IL-17R: interleukin-17 receptor.