Paradoxical psoriasis induced by IL-17 antagonists.

Background The paradoxical occurrence of psoriasis triggered by Interleukin-17 (IL-17) inhibitors is notable due to its prominent symptoms and the therapeutic dilemma it presents for follow-up care. Objective To describe cases in our clinic, perform an in-depth literature review, and suggest the most probable mechanisms of action. Method We conducted a literature review on published cases of IL-17 inhibitor-induced psoriasis. Results We found 22 articles reporting 30 cases of IL-17 inhibitor-induced paradoxical psoriasis, primarily observed in patients with a previous psoriasis history. Almost 60% of cases showed a change in lesion morphology, with the plaque or pustular type being prevalent. About 73.3% of patients had to discontinue the implicated drug, leading to partial or complete symptom resolution. The mechanism behind this response seemed to involve IL-17 inhibitors downregulating Tumour Necrosis Factor alpha (TNF-α), subsequently upregulating plasmacytoid dendritic cells and triggering unopposed IFN-alpha (IFN-α) production. Limitation Data are confined to case reports and case series. Conclusion More assertive measures are recommended for treating paradoxical psoriasis induced by IL-17 inhibitors than those caused by TNF-α inhibitors. Reintroducing an IL-17 inhibitor is not advised, as patients did not show improvement.