Intracellular Ca2+ contributes to K+-induced increase in renal kallikrein secretion

A common polymorphism in the tissue kallikrein gene is associated with increased urinary excretions of calcium and sodium in Japanese volunteers

Tissue kallikrein is an enzyme involved in the release of kinin in peripheral tissues. It is believed to regulate hemodynamics and electrolyte transport in the kidney. The present study analyzed polymorphisms of tissue kallikrein in Japanese volunteers and examined the associations between allele H in the promoter region, which has been shown to have decreased promoter activity, and urinary kallikrein activity and physiological parameters in subjects on an ad libitum diet. Ninety and 73 volunteers were analyzed for the promoter and coding regions of the tissue kallikrein gene, respectively. The allelic frequency of allele H was found to be 24%. One synonymous and three non-synonymous polymorphisms were found in the coding regions. Urinary kallikrein activity was not significantly decreased in subjects with allele H compared to those without allele H, although they were low in two homozygotes of allele H. Urinary excretions of calcium and sodium were larger in the subjects with allele H than in those without. It is concluded that allele H is a common polymorphism in Japanese and may contribute to decreased reabsorptions of calcium and sodium in the kidney. Further interventional studies are needed to clarify the phenotype of allele H with respect to renal electrolyte handling.

Specific inhibition of tissue kallikrein 1 with a human monoclonal antibody reveals a potential role in airway diseases

KLK1 (tissue kallikrein 1) is a member of the tissue kallikrein family of serine proteases and is the primary kinin-generating enzyme in human airways. DX-2300 is a fully human antibody that inhibits KLK1 via a competitive inhibition mechanism (Ki=0.13 nM). No binding of DX-2300 to KLK1 was observed in a surface-plasmon-resonance biosensor assay when KLK1 was complexed to known active-site inhibitors, suggesting that DX-2300 recognizes the KLK1 active site. DX-2300 did not inhibit any of the 21 serine proteases that were each tested at a concentration of 1 microM. We validated the use of DX-2300 for specific KLK1 inhibition by measuring the inhibition of KLK1-like activity in human urine, saliva and bronchoalveolar lavage fluid, which are known to contain active KLK1. In human tracheobronchial epithelial cells grown at the air/liquid interface, DX-2300 blocked oxidative-stress-induced epidermal-growth-factor receptor activation and downstream mucus cell proliferation and hypersecretion, which have been previously shown to be mediated by KLK1. In an allergic sheep model of asthma, DX-2300 inhibited both allergen-induced late-phase bronchoconstriction and airway hyper-responsiveness to carbachol. These studies demonstrate that DX-2300 is a potent and specific inhibitor of KLK1 that is efficacious in in vitro and in vivo models of airway disease.