Identification and occurrence of mRNAs for components of the kallikrein-kinin system in human skin and in skin diseases.

Bradykinin and kallidin are released during dermal injury and inflammation as a result of activation of kallikreins which cleave high- and low-molecular weight kininogen (HMW and LMW kininogen, respectively). In the skin, kinins are involved, e.g., as co-mitogens in cellular proliferation or in processes propagating pain and inflammation. The aim of our study was to investigate the specific occurrence of mRNAs for components of the kallikrein-kinin system in normal human skin and in skin biopsies of patients with selected skin diseases (psoriasis, lichenificated atopic eczema, basalioma). In normal skin, reverse transcription polymerase chain reaction (RT-PCR) with specific primer pairs followed by separation of products by polyacrylamide gel electrophoresis (PAGE) revealed the presence of mRNAs for tissue kallikrein, for the B2 and the B1 bradykinin receptors, but not for kininogen. In biopsies of lichenificated atopic eczema and basalioma, additionally, the mRNAs for HMW and LMW kininogen were detected, whereas in psoriatic skin mRNA for HMW kininogen was not expressed. These differences in mRNA expression may reflect the different contribution of kallikrein-kinin system components to the maintenance of chronic skin diseases like psoriasis. In acute dermal reactions occurring in lichenificated atopic eczema or in basalioma, tissue mRNA for HMW kininogen appears to be arisen from sources not pre-existing in normal skin.