ABSTRACT
Human tissue Kallikrein-related peptidases (hKLKs) are serine proteases distributed in several tissues that are involved in several biological processes. In skin, many are responsible for skin desquamation in the Stratum Corneum (SC) of the epidermis, specially hKLK5, hKLK7, hKLK6, hKLK8, and hKLK14. In SC, hKLKs cleave proteins of corneodesmosomes, an important structure responsible to maintain corneocytes attached. As part of skin desquamation, hKLKs are also involved in skin diseases with abnormal desquamation and inflammation, such as Atopic Dermatitis (AD), psoriasis, and the rare disease Netherton Syndrome (NS). Many studies point to hKLK overexpression or overactive in skin diseases, and they are also part of the natural skin inflammation process, through the PAR2 cleavage pathway. Therefore, the control of hKLK activity may offer successful treatments for skin diseases, improving the quality of life in patients. Diseases like AD, Psoriasis, and NS have an impact on social life, causing pain, itchy and mental disorders. In this review, we address the molecular mechanisms of skin desquamation, emphasizing the roles of human tissue Kallikrein-related peptidases, and the promising therapies targeting the inhibition of hKLKs.
ABSTRACT
Human tissue kallikreins (KLKs) constitute a family of 15 serine proteases that are distributed in various tissues and implicated in several pathological disorders. KLK7 is an unusual serine protease that presents both trypsin-like and chymotrypsin-like specificity and appears to be upregulated in pathologies that are related to skin desquamation processes, such as atopic dermatitis, psoriasis and Netherton syndrome. In recent years, various groups have worked to develop specific inhibitors for this enzyme, as KLK7 represents a potential target for new therapeutic procedures for diseases related to skin desquamation processes. In this work, we selected nine different single-chain variable fragment antibodies (scFv) from a human naïve phage display library and characterized their inhibitory activities against KLK7. The scFv with the lowest IC50 against KLK7 was affinity maturated, which resulted in the generation of four new scFv-specific antibodies for the target protease. These new antibodies were expressed in the scFv-Fc format in HEK293-6E cells, and the characterization of their inhibitory activities against KLK7 showed that three of them presented IC50 values lower than that of the original antibody. The cytotoxicity analysis of these recombinant antibodies demonstrated that they can be safely used in a cellular model. In conclusion, our research showed that in our case, a phage-display methodology in combination with enzymology assays can be a very suitable tool for the development of inhibitors for KLKs, suggesting a new strategy to identify therapeutic protease inhibitors for diseases related to uncontrolled kallikrein activity.
