B1 and B2 kinin receptor participation in hyperproliferative and inflammatory skin processes in mice

BackgroundKinins are released during dermal injury and inflammation and seem to contribute to the pathogenesis of cutaneous diseases.ObjectiveParticipation of kinins in skin inflammatory process was evaluated using knockout mice and non-peptide kinin receptor antagonists.MethodsChronic skin inflammation was induced by multiple applications of TPA in mice ear.ResultsThe B2 knockout mice (B2−/−) showed a significant increase of ear weight (23 ± 10%) and epidermal cellular hyperproliferation and acanthosis formation upon histological analysis when compared with wildtype mice. Also, evaluation of PCNA levels by Western blot and immunohistochemistry confirmed the increase in the epidermis hyperproliferation in the ear skin of B2−/− mice. In contrast, no modification in these parameters was detected in B1 knockout mice (B1−/−). However, mice lacking both kinin receptors (B1B2−/−) presented a considerable reduction of epidermis thickness and in PCNA levels. Following the establishment of skin inflammation (5th day of TPA application) treatment with the non-peptide antagonists SSR 240612 (B1 receptor antagonist), FR 173657 (B2 receptor antagonist), or SSR 240612 plus FR 173657 topically applied, caused a significant inhibition of ear weight (20 ± 5%, 34 ± 4% and 32 ± 6%, respectively). In the histological analysis, the antagonists produced a reduction in epidermal hyperplasia and acanthosis formation; but the treatment with a combination of the two antagonists did not increase efficacy.ConclusionKinin receptors seem to be involved in the control of the keratinocyte hyperproliferative process, and non-peptide kinin receptor antagonists may be useful tools in the treatment of hyperproliferative skin disorders.