The use of an interleukin β antibody is currently being investigated in the clinic for the treatment of acne, a dermatological disorder affecting 650M persons globally. Inhibiting the protease responsible for the cleavage of inactive pro-IL1β into active IL-1β, caspase-1, could be an alternative small molecule approach. This report describes the discovery of uracil 20, a potent (38 nM in THP1 cells assay) caspase-1 inhibitor for the topical treatment of inflammatory acne. The uracil series was designed according to a published caspase-1 pharmacophore model involving a reactive warhead in P1 for covalent reversible inhibition and an aryl moiety in P4 for selectivity against the apoptotic caspases. Reversibility was assessed in an enzymatic dilution assay or by using different substrate concentrations. In addition to classical structure-activity-relationship exploration, topical administration challenges such as phototoxicity, organic and aqueous solubility, chemical stability in solution, and skin metabolic stability are discussed and successfully resolved.
Staphylococcus aureus colonization is thought to contribute to the pathophysiology of atopic dermatitis (AD). AD patients exhibit reduced levels of cutaneous antimicrobial peptides (AMPs), which may explain their increased susceptibility to infections. Using an in vitro reconstructed human epidermis (RHE) model, we sought to determine whether topical application of a non-replicating probiotic, heat-treated Lactobacillus johnsonii NCC 533 (HT La1), could inhibit S. aureus adhesion to skin and boost cutaneous innate immunity. We found that application of HT La1 suspension to RHE samples reduced the binding of radiolabelled S. aureus by up to 74%. To investigate a potential effect of HT La1 on innate immunity, we analysed the expression of nine AMP genes, including those encoding beta defensins and S100 proteins, following topical application of HT La1 in suspension or in a daily moisturizer lotion. Analysed genes were induced by up to fourfold in a dose-dependent manner by HT La1 in suspension and by up to 2.4-fold by HT La1 in the moisturizer lotion. Finally, using ELISA and immunohistochemical detection, we evaluated the expression and secretion of the AMPs hBD-2 and psoriasin and determined that both proteins were induced by topical HT La1, particularly in the stratum corneum of the RHE. These findings demonstrate that a topically applied, non-replicating probiotic can modulate endogenous AMP expression and inhibit binding of S. aureus to an RHE model in vitro. Moreover, they suggest that a topical formulation containing HT La1 could benefit atopic skin by enhancing cutaneous innate immunity and reducing S. aureus colonization.
With possible implications in multiple autoimmune diseases, the retinoic acid receptor-related orphan receptor RORγ has become a sought-after target in the pharmaceutical industry. Herein are described the efforts to identify a potent RORγ inverse agonist compatible with topical application for the treatment of skin diseases. These efforts culminated in the discovery of N-(2,4-dimethylphenyl)-N-isobutyl-2-oxo-1-[(tetrahydro-2H-pyran-4-yl)methyl]-2,3-dihydro-1H-benzo[d]imidazole-5-sulfonamide (CD12681), a potent inverse agonist with in vivo activity in an IL-23-induced mouse skin inflammation model.
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