IL-36-Driven Inflammation in Generalized Pustular Psoriasis: Immunological Insights from Plaque Psoriasis and Implications for Targeted Therapy

Generalized pustular psoriasis (GPP) is a rare, severe, and potentially life-threatening inflammatory dermatosis increasingly recognized as a distinct disease entity rather than a variant of plaque psoriasis. Emerging evidence indicates that GPP is primarily driven by dysregulation of the interleukin-36 (IL-36) signaling axis, leading to amplification of proinflammatory cascades in keratinocytes and a predominantly innate, neutrophil-driven immune response. This promotes rapid neutrophil recruitment, sterile pustule formation, and abrupt cutaneous and systemic inflammation. Consistent with this, GPP demonstrates a greater predominance of innate immune and neutrophil-driven inflammation, whereas plaque psoriasis is more strongly associated with IL-23/Th17-mediated adaptive immune responses. Transcriptomic and genetic studies further support this distinction, demonstrating enrichment of IL-36-associated and neutrophil-related signatures, activation of MyD88-dependent pathways, and mutations in genes regulating the IL-36 axis, including IL36RN, AP1S3, and CARD14. Consequently, conventional systemic therapies and biologics targeting TNF-α, IL-17, and IL-23 pathways show variable efficacy and may act more slowly in GPP. In contrast, IL-36 receptor inhibitors represent a more mechanism-aligned approach and have demonstrated rapid and clinically meaningful responses in acute flares. However, important gaps remain, including the lack of validated biomarkers and limited data on long-term treatment outcomes. This review provides an integrated perspective on IL-36-driven inflammation in GPP, including comparison with plaque psoriasis, and outlines its implications for mechanism-based therapeutic approaches.