hK5 and hK7, two serine proteinases abundant in human skin, are inhibited by LEKTI domain 6

Backgroudn Several skin diseases and atopic disorders including Netherton syndrome and atopic dermatitis have been associated with mutations and deviations of expression of SPINK5, the gene encoding the human 15-domain serine proteinase inhibitor LEKTI. The biochemical mechanisms underlying this phenomenon have not yet been fully clarified. Objectives To identify target proteinases of LEKTI important for processes of desquamation and inflammation of the skin which will enable the development of specific drugs. Methods The inhibitory activities of LEKTI domains 6 and 15 were tested on a number of commercially available serine proteinases and also on the purified kallikreins hK5 and hK7. In addition, recombinant hK5 was used. Results LEKTI domain 6 is a potent inhibitor of hK5 and hK7, whereas LEKTI domain 15 exhibits inhibitory activity on plasmin. hK5 and hK7 in particular are relevant to skin disorders. Conclusions The inhibition of hK5 and hK7 by LEKTI domain 6 indicates an important regulatory role of LEKTI in processes of skin desquamation and inflammation, which may explain the severe pathological symptoms associated with abnormalities of SPINK5 and/or its expression. Thus, LEKTI represents a potential drug for the treatment of these disorders.