T-helper 17 and T-helper 1 immune pathways (Th17/Th1)

The Th17 and Th1 immune pathways represent distinct lineages of CD4+ T-helper cells that play pivotal roles in host defense and autoimmunity. The Th1 pathway, driven by interleukin-12 (IL-12), produces interferon-gamma (IFN-gamma) to activate macrophages and combat intracellular pathogens [StatPearls, 2023]. In contrast, the Th17 pathway is regulated by interleukin-23 (IL-23) and produces cytokines like IL-17A, IL-17F, and IL-22, which are essential for clearing extracellular bacteria and fungi at mucosal surfaces [Nature Reviews Immunology, 2020]. Overactivation of these pathways is strongly linked to the pathogenesis of chronic inflammatory diseases such as psoriasis, psoriatic arthritis, and inflammatory bowel disease [PubMed, 2021]. Modern biologics target these pathways by neutralizing specific cytokines or blocking their receptors, effectively reducing systemic inflammation. For instance, drugs like ustekinumab target the shared p40 subunit of IL-12 and IL-23, while secukinumab specifically inhibits IL-17A [FDA, 2024]. However, because these pathways are vital for immunity, their inhibition can lead to safety concerns such as an increased risk of opportunistic infections or the exacerbation of pre-existing conditions like Crohn's disease [Journal of Clinical Investigation, 2019].

Other names

Th17/Th1 axisT-helper 17 and T-helper 1 signalingIL-17/IFN-gamma axisTh17 and Th1 cell differentiation pathwaysTh17/Th1 immune pathways

Therapeutic agents modulate these pathways by binding to and neutralizing key pro-inflammatory cytokines (e.g., IL-17A, IL-12, IL-23) or by blocking their cognate receptors (e.g., IL-17RA), thereby preventing downstream signaling through the JAK-STAT or other inflammatory cascades [Nature Reviews Drug Discovery, 2022].