076 | Iron-driven redox dysregulation fuels psoriatic signaling in CARD14 e138a mutant keratinocytes

Cristiana Galeano¹, Anna Martina Battaglia¹, Emanuele Giorgio¹, Lavinia Petriaggi¹, Giuseppe Natali², Flavia Biamonte¹ | ¹Laboratory of Biochemistry and Cell Biology, Department of Experimental and Clinical Medicine, Magna Graecia University of Catanzaro, Italy; ²Department of Life Science, Magna Graecia University of Catanzaro, Italy.

Psoriasis is a chronic inflammatory skin disease characterized by aberrant keratinocyte differentiation and hyperproliferation, frequently associated with gain-of-function mutations in CARD14, a key scaffold protein activating NF-κB–dependent pro-inflammatory signaling. Here, HaCaT human keratinocytes were stably transfected with constructs encoding the CARD14sh (short; prominently expressed in skin) isoform and the psoriasis-associated mutants E142G, R38C, and E138A. Among them, E138A showed the most pronounced nuclear translocation of NF-κB, accompanied by increased expression of PTGS2 and the pro-inflammatory mediators IL-23, IL-6, TNF-α, and DEFB3. This inflammatory signature correlated with enhanced proliferation and a KRT1/KRT17 switch, a hallmark of psoriatic keratinocyte dedifferentiation. Since inflammation alone does not fully account for psoriasis pathogenesis, CARD14 mutants were further analyzed for redox homeostasis. Notably, E138A cells displayed increased cytosolic and mitochondrial reactive oxygen species (ROS), measured by DCF and MitoSOX assays, together with downregulation of the antioxidant proteins GPX4 and FTH1. Given the central role of iron in redox regulation, the labile iron pool (LIP) was assessed by flow cytometry using FerroOrange. LIP levels remained unaltered exclusively in E138A cells despite reduced FTH1 expression, suggesting preferential iron utilization consistent with their hyperproliferative phenotype. Importantly, treatment with deferoxamine, a clinically used iron chelator, selectively inhibited the KRT1/KRT17 switch and downregulated most inflammatory markers in E138A mutant keratinocytes, with minimal effects on other mutants. Overall, these findings suggest that iron availability sustains the redox imbalance, inflammatory signaling, and aberrant differentiation driven by the CARD14 E138A mutation, identifying iron metabolism as a potential therapeutic vulnerability in psoriasis-associated CARD14 gain-of-function contexts.