Cocktails of KLK5 Protease Inhibitors and Anti-TNFα Therapeutics: an Effective Treatment for Netherton Syndrome.

Netherton syndrome (NS) is a rare, severe type of ichthyosis, often lethal in neonates, for which there is no therapy. Spink5-/- mice recapitulate major NS hallmarks and die homogeneously within 5 h from birth due to severe epidermal barrier defect leading to dehydration. Spink5-/-Klk5-/- mice survive neonatal lethality, indicating that KLK5 could be a drug target for NS. Nevertheless, after a week, these mice developed epidermal inflammation and signs of barrier defect leading to lethality. Here we tested whether anti-TNFα strategy in combination with anti-KLK5 could provide a long-term effective therapy for NS. Deletion of Tnfa in Spink5-/- suppressed the inflammatory phenotype but did not rescue neonatal lethality of Spink5-/- indicating that anti-TNFα therapy alone would not be sufficient to treat NS. Interestingly, in Spink5-/-Klk5-/-Tnfa-/- mice, NS features were rescued, and mice lived normally for 16-18 months. For the first time, evidence is provided that a combination of anti-TNFα and anti-KLK5 therapeutics represents an effective therapeutic strategy for NS. Notably, anti-TNFα factors are marketed and used widely, while LMW KLK5 inhibitors are being developed.