Decreased plasma kallikrein 5 concentrations in patients with chronic spontaneous urticaria

Little is known about the role of the kallikrein-kinin system in chronic spontaneous urticaria (CSU). Kallikrein 5 (KLK5), a trypsin-like enzyme, is the most abundant in the skin and plays a role in itching and inflammatory reaction. In this study, we determined plasma KLK5 concentration, and its associations with acute phase response in CSU patients. Concentrations of KLK5 in plasma and CRP in serum were measured in patients with CSU of varying severity and in the healthy subjects. Plasma KLK5 concentrations were significantly lower in CSU (all) and moderate-severe CSU patients, as compared with the controls. There were no significant differences in KLK5 concentration in mild CSU patients as compared with the healthy subjects and moderate-severe CSU patients. No correlation was observed between KLK5 and CRP concentrations in the patients. It may be considered that circulating kallikrein 5 is down-regulated in CSU patients, however its potential role and the possible underlying mechanism are unknown.