Modulation of the expression and activity of cathepsin S in reconstructed human skin by neohesperidin dihydrochalcone

Dysregulation of cathepsin S (Cat S), a cysteine protease involved in extracellular-matrix and basement membrane (BM) degradation, is a concomitant feature of several inflammatory skin diseases. Therefore, Cat S has been suggested as a potential therapeutic target. Flavonoids, which were identified as regulatory molecules of various proteolytic enzymes, exert beneficial effects on skin epidermis. Herein, thirteen flavonoid compounds were screened in vitro and in silico and neohesperidin dihydrochalcone (NHDC) was identified as a potent, competitive, and selective inhibitor (K-i=8 +/- 1 mu M) of Cat S. Furthermore, Cat S-dependent hydrolysis of nidogen-1, a keystone protein of BM architecture, as well elastin, collagens I and IV was impaired by NHDC, while both expression and activity of Cat S were significantly reduced in NHDC-treated human keratinocytes. Moreover, a reconstructed human skin model showed a significant decrease of both mRNA and protein levels of Cat S after NHDC treatment. Conversely, the expression of nidogen-1 was significantly increased. NHDC raised IL-10 expression, an anti-inflammatory cytokine, and mediated STAT3 signaling pathway, which in turn dampened Cat S expression. Our findings support that NHDC may represent a valuable scaffold for structural improvement and development of Cat S inhibitors to preserve the matrix integrity and favor skin homeostasis during inflammatory events. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study identified neohesperidin dihydrochalcone (NHDC) as a potent inhibitor of cathepsin S (Cat S), which plays a role in the degradation of extracellular-matrix and basement membrane. NHDC inhibited the hydrolysis of key proteins in the basement membrane and reduced the expression and activity of Cat S in human keratinocytes. Furthermore, NHDC increased the expression of the anti-inflammatory cytokine IL-10 and mediated the STAT3 signaling pathway, leading to the suppression of Cat S expression.