Exogenous kallikrein protects against diabetic nephropathy.

The kallikrein-kinin system has been shown to be involved in the development of diabetic nephropathy, but specific mechanisms are not fully understood. Here, we determined the renal-protective role of exogenous pancreatic kallikrein in diabetic mice and studied potential mechanisms in db/db type 2 diabetic and streptozotocin-induced type 1 diabetic mice. After the onset of diabetes, mice were treated with either pancreatic kallikrein (db/db+kallikrein, streptozotocin+kallikrein) or saline (db/db+saline, streptozotocin+saline) for 16 weeks, while another group of streptozotocin-induced diabetic mice received the same treatment after onset of albuminuria (streptozotocin'+kallikrein, streptozotocin'+saline). Db/m littermates or wild type mice were used as non-diabetic controls. Pancreatic kallikrein had no effects on body weight, blood glucose and blood pressure, but significantly reduced albuminuria among all three groups. Pathological analysis showed that exogenous kallikrein decreased the thickness of the glomerular basement membrane, protected against the effacement of foot process, the loss of endothelial fenestrae, and prevented the loss of podocytes in diabetic mice. Renal fibrosis, inflammation and oxidative stress were reduced in kallikrein-treated mice compared to diabetic controls. The expression of kininogen1, tissue kallikrein, kinin B1 and B2 receptors were all increased in the kallikrein-treated compared to saline-treated mice. Thus, exogenous pancreatic kallikrein both prevented and ameliorated diabetic nephropathy, which may be mediated by activating the kallikrein-kinin system.

Inhibition of the effects of different agonists on the rat uterus and guinea-pig ileum by Mandevilla velutina extract

O extrato de Mandevilla velutina inibe as contraçöes induzidas pela bradicinina e cininogenases (calicreína, tripsina e tonina) no útero de rata. As contraçöes por angiotensina II e mesmo por cloreto de bário também foram inibidas, quando o íleo de cobaia foi usado, a contraçäo evocada pela histamina foi inibida. Esses experimentos sugerem que a inibiçäo causada pelo extrato de Mandevilla velutina näo é seletiva para bradicinina

Kallikrein stimulates arachidonic acid release and production of prostaglandins from TEA3A1 endocrine thymic epithelial cells.

Using TEA3A1 rat endocrine thymic epithelial cells, we demonstrated that kallikrein (EC 3.4.21.35) not only stimulated the release of arachidonic acid (AA) and its metabolites from TEA3A1 cells but also enhanced the intracellular synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) by approx. 2-fold. The stimulatory effect of kallikrein was dose- and time-dependent and could be blocked by aprotinin, a kallikrein inhibitor. It was found that the phospholipase A inhibitors ONO RS082 [2-(p-amylcinnamoyl)amino-4-chlorobenzoic acid], and mepacrine (6-chloro-9-[(4-dimethylamino)-1-methyl)]amino-2-methoxyacridine; quinacrine) also inhibited the kallikrein-stimulated release of AA and its metabolites. It is suggested that the kallikrein-induced stimulatory effect might be mediated through a phospholipase A2 pathway. The effect of bradykinin was studied and no significant stimulation was observed, even at a high dose (10 micrograms/ml). This suggested that the formation of kinin does not have a role in the kallikrein-induced stimulation of AA release from TEA3A1 cells. Furthermore, the effect of kallikrein was also totally abolished by adding pepstatin A, a known inhibitor of renin, pepsin and cathepsin D which does not inhibit kallikrein itself. This indicates that kallikrein did not act on the phospholipase-like enzyme directly. There is at least one more enzyme, a pepstatin A-inhibitable proteinase, that acts as a mediator for kallikrein-induced regulation of AA release.