Abstract
CARD14 gain-of-function mutations cause psoriasis in humans and mice. Together with BCL10 and the protease MALT1, mutant CARD14 forms a signaling node that mediates increased NF-κB signaling and proinflammatory gene expression in keratinocytes. However, it remains unclear whether psoriasis in response to CARD14 hyperactivation is keratinocyte-intrinsic or requires CARD14 signaling in other cells. Moreover, the in vivo effect of MALT1 targeting on mutant CARD14-induced psoriasis has not yet been documented. Here, we show that inducible keratinocyte-specific expression of CARD14E138A in mice rapidly induces epidermal thickening and inflammation as well as increased expression of several genes associated with psoriasis in humans. Keratinocyte-specific MALT1 deletion as well as oral treatment of mice with a specific MALT1 protease inhibitor strongly reduces psoriatic skin disease in CARD14E138A mice. Together, these data illustrate a keratinocyte-intrinsic causal role of enhanced CARD14/MALT1 signaling in the pathogenesis of psoriasis and show the potential of MALT1 inhibition for the treatment of psoriasis.