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.

Mass-spectrometric identification of T-kininogen I/thiostatin as an acute-phase inflammatory protein suppressed by curcumin and capsaicin.

Curcumin and capsaicin are dietary xenobiotics with well-documented anti-inflammatory properties. Previously, the beneficial effect of these spice principles in lowering chronic inflammation was demonstrated using a rat experimental model for arthritis. The extent of lowering of arthritic index by the spice principles was associated with a significant shift in macrophage function favoring the reduction of pro-inflammatory molecules such as reactive oxygen species and production and release of anti-inflammatory metabolites of arachidonic acid. Beyond the cellular effects on macrophage function, oral administration of curcumin and capsaicin caused alterations in serum protein profiles of rats injected with adjuvant to develop arthritis. Specifically, a 72 kDa acidic glycoprotein, GpA72, which was elevated in pre-arthritic rats, was significantly lowered by feeding either curcumin or capsaicin to the rats. Employing the tandem mass spectrometric approach for direct sequencing of peptides, here we report the identification of GpA72 as T-kininogen I also known as Thiostatin. Since T-kininogen I is an early acute-phase protein, we additionally tested the efficiency of curcumin and capsaicin to mediate the inflammatory response in an acute phase model. The results demonstrate that curcumin and capsaicin lower the acute-phase inflammatory response, the molecular mechanism for which is, in part, mediated by pathways associated with the lowering of T-kininogen I.

Neuronal differentiation of P19 embryonal carcinoma cells modulates kinin B2 receptor gene expression and function.

Kinins are vasoactive oligopeptides generated upon proteolytic cleavage of low and high molecular weight kininogens by kallikreins. These peptides have a well established signaling role in inflammation and homeostasis. Nevertheless, emerging evidence suggests that bradykinin and other kinins are stored in the central nervous system and may act as neuromediators in the control of nociceptive response. Here we show that the kinin-B2 receptor (B2BKR) is differentially expressed during in vitro neuronal differentiation of P19 cells. Following induction by retinoic acid, cells form embryonic bodies and then undergo neuronal differentiation, which is complete after 8 and 9 days. Immunochemical staining revealed that B2BKR protein expression was below detection limits in nondifferentiated P19 cells but increased during the course of neuronal differentiation and peaked on days 8 and 9. Measurement of [Ca(2+)](i) in the absence and presence of bradykinin showed that most undifferentiated cells are unresponsive to bradykinin application, but following differentiation, P19 cells express high molecular weight neurofilaments, secrete bradykinin into the culture medium, and respond to bradykinin application with a transient increase in [Ca(2+)](i). However, inhibition of B2BKR activity with HOE-140 during early differentiation led to a decrease in the size of embryonic bodies formed. Pretreatment of differentiating P19 cells with HOE-140 on day 5 resulted in a reduction of the calcium response induced by the cholinergic agonist carbamoylcholine and decreased expression levels of M1-M3 muscarinic acetylcholine receptors, indicating crucial functions of the B2BKR during neuronal differentiation.

Characterization of a tissue kallikrein inhibitor isolated from Bauhinia bauhinioides seeds: inhibition of the hydrolysis of kininogen related substrates.

Trypsin inhibitors were purified from a saline extract of Bauhinia bauhinioides seeds by ion-exchange column chromatography on DEAE-Sephadex, gel filtration on Superose 12 column, Mono Q ion-exchange chromatography or, alternatively, by affinity chromatography on trypsin-Sepharose. Both B. bauhinioides isolated inhibitors, BbTI-I and BbTI-II, inhibit trypsin being the dissociation constant 0.6 and 0.36 nM, respectively. BbTI-II only inhibits porcine pancreatic kallikrein hydrolysis of H-Pro-Phe-Arg-AMC (Ki 2.0 nM); the bradykinin-containing sequence LGMISLMKRPPGFSPFRSSRI-NH2 and the two kininogen related flanking quenched substrates Abz-MISLMKRP-EDDnp (Ki 2.0 nM) and Abz-FRSSRQ-EDDnp (Ki 2.5 nM).

Potassium supplement upregulates the expression of renal kallikrein and bradykinin B2 receptor in SHR.

High potassium intake is known to attenuate hypertension, glomerular lesion, ischemic damage, and stroke-associated death. Our recent studies showed that expression of recombinant kallikrein by somatic gene delivery reduced high blood pressure, cardiac hypertrophy, and renal injury in hypertensive animal models. The aim of this study is to explore the potential role of the tissue kallikrein-kinin system in blood pressure reduction and renal protection in spontaneously hypertensive rats (SHR) on a high-potassium diet. Young SHR were given drinking water with or without 1% potassium chloride for 6 wk. Systolic blood pressure was significantly reduced beginning at 1 wk, and the effect lasted for 6 wk in the potassium-supplemented group compared with that in the control group. Potassium supplement induced 70 and 40% increases in urinary kallikrein levels and renal bradykinin B2 receptor density, respectively (P < 0.05), but did not change serum kininogen levels. Similarly, Northern blot analysis showed that renal kallikrein mRNA levels increased 2.7-fold, whereas hepatic kininogen mRNA levels remained unchanged in rats with high potassium intake. No difference was observed in beta-actin mRNA levels in the kidney or liver of either group. Competitive RT-PCR showed a 1.7-fold increase in renal bradykinin B2 receptor mRNA levels in rats with high potassium intake. Potassium supplement significantly increased water intake, urine excretion, urinary kinin, cAMP, and cGMP levels. This study suggests that upregulation of the tissue kallikrein-kinin system may be attributed, in part, to blood pressure-lowering and diuretic effects of high potassium intake.

[Activation of bradykinin formation cascade on receiving autologous blood transfusion through a white cell-reduction filter in a patient treated with an ACE inhibitor].

We have experienced a case of anaphylactoid reaction on receiving autologous blood transfusion through a WBC filter for packed red blood cell (PRBC). The patient was a 71-year-old man with a history of hypertension treated with oral antihypertensive drug; enalapril, an angiotensin converting enzyme (ACE) inhibitor, who received anesthesia for Y-graft replacement. Autologous blood was obtained after the induction of general anesthesia in the operating room. Upon starting to return the stored blood with an unintentional use of a WBC filter, arterial blood pressure (ABP) fell within the first minute of the transfusion. We obtained three blood samples; pre-filtered blood (PRE), postfiltered blood (POST) and arterial blood (CIRC) after the event, and analyzed concentrations of bradykinin (BK), high molecular weight kininogen (HMWK) and high molecular weight kininogen-light chain (HMWK-LC). BK was higher in POST than in PRE. HMWK was lower in POST than in PRE, while HMWK-LC was higher in POST than in PRE. HMWK in CIRC was lower than in PRE, and HMWK-LC was higher in CIRC than in PRE. HMWK and HMWK-LC changes after the event suggest that BK formation cascade in the patient was activated on receiving the transfusion. ACE inhibitors were reported to augment such activation. The WBC filter has the negatively charged surface on filteration material and may activate the cascade. While WBC filters can avoid transfusion related reactions, hemodynamic responses should be watched closely in patients treated with ACE inhibitors.

Specific inhibition of plasma kallikrein modulates chronic granulomatous intestinal and systemic inflammation in genetically susceptible rats.

The kallikrein-kinin (K-K) (contact) system is activated during acute and chronic relapsing phases of enterocolitis induced in genetically susceptible Lewis rats by intramural injection of peptidoglycan-polysaccharide (PG-APS). Using the selective plasma kallikrein inhibitor P8720, we investigate whether activation of the K-K system plays a primary role in chronic granulomatous intestinal and systemic inflammation in this model. Group I (negative control) received human serum albumin intramurally. Group II (treatment) received PG-APS intramurally and P8720 orally. Group III (positive control) received PG-APS intramurally and albumin orally. P8720 attenuated the consumption of the contact proteins, high molecular weight kininogen (P<0.03), and factor XI (P<0.04) in group II vs. group III. P8720 decreased chronic intestinal inflammation measured by blinded gross (P<0.01) and histologic (P<0.0005) scores as well as systemic complications (arthritis, splenomegaly, hepatomegaly, leukocytosis, and acute-phase reaction) (P<0.01) in group II as compared with group III. We conclude that relapsing chronic enterocolitis and systemic complications are in part due to plasma K-K system activation, and that inhibition of this pathway is a potential therapeutic approach to human inflammatory bowel disease and associated extraintestinal manifestations.

Activation of the kallikrein-kinin system in arthritis and enterocolitis in genetically susceptible rats: modulation by a selective plasma kallikrein inhibitor.

We have developed models of acute and chronic inflammatory arthritis and enterocolitis using peptidoglycan-polysaccharide injected intraperitoneally or subserosally (intramurally) into the distal ileum and cecum. Acute inflammation occurs in both Buffalo and Lewis rats, characterized by inflammation of the injected areas of the intestine. However, only the genetically susceptible Lewis rat develops chronic synovitis and joint erosion or adhesions and granulomatous enterocolitis. In the Lewis rat but not the Buffalo rat, these changes are accompanied by a decrease in plasma prekallikrein and high-molecular-weight kininogen, reflecting activation of the kallikrein-kinin system. Pretreatment with a specific plasma kallikrein inhibitor modulates the acute and chronic arthritis. The same inhibitor partially abrogates the acute changes characteristic of enterocolitis, and preliminary data suggest similar results in the chronic model. The results of these studies indicate that the kallikrein-kinin system plays an important role in arthritis and enterocolitis induced by bacterial products and that kallikrein inhibitors are potential therapeutic agents for inflammatory arthritis and inflammatory bowel disease.

Conformational changes in low molecular weight kininogen alters its ability to bind to endothelial cells.

The plasma kininogens, high (HK) and low (LK) molecular weight kininogens, are the parent proteins for bradykinin, a potent vasoactive peptide that locally influences vascular biology. Binding of both HK and LK to the endovascular wall contributes to bradykinin delivery. Recently, we found one preparation of LK (LKd) which had reduced inhibition of biotin-HK binding to endothelium. The functional defect in LKd was not merely due to bradykinin loss because two preparations of bradykinin-free LK blocked biotin-HK binding. However, using two different particular monoclonal antibodies to bradykinin, LKd, but no other preparation of LK, had its epitope to bradykinin exposed on non-reduced samples on immunoblot. These data suggested that LKd had an altered conformation which exposed the amino terminal arginine of bradykinin to antigenic detection. The altered conformation of LKd allowed it to be more susceptible to trypsin proteolysis. On circular dichroism, the percentage of alpha-helix was significantly increased, indicating an alteration in the protein. This alteration in LKd was not due to a loss of molecular mass of the protein. On laser desorption mass spectroscopy, the molecular mass of LKd was similar to the other preparations of LK. Investigations were performed to ascertain the mechanism by which LKd had altered ability to bind to cells. LKd was found to be proteolyzed by an unknown protease at the beginning of domain 2 between threonine119 and alanine120. Reduction of functional LK with dithiothreitol to expose its bradykinin epitope did not produce the LKd defect. Proteolysis of functional LK with plasma kallikrein, elastase followed by plasma kallikrein, chymotrypsin, or bromelain also did not produce the defect seen in LKd. These combined data indicated that LK maintains a particular conformation that allows the protein to orient itself such that it can bind to endothelial cells. Proteolysis in the surface exposed region between domains 1 and 2 probably allows for the protein to unfold and contributes to its lost ability to bind to endothelial cells.

Immunolocalization of high molecular weight kininogen (HKg) and T kininogen (TKg) in the rat hypothalamus.

Specific HKg immunostaining detected with antiserum against the light chain (LC) of HKg was restricted to SRIF neurons of the hypothalamic periventricular area projecting to median eminence (ME). Heavy chain (HC) immunoreactivity related to HKg and/or low molecular weight kininogen (LKg) was found in some other hypothalamic territories. Specific TKg was mainly associated with vasopressin in neurons of suprachiasmatic (SCN), supraoptic (SON) and paraventricular (PVN) nuclei. By direct RIA, hypothalamus was found to contain the highest level of TKg (10ng/mg protein) and after trypsin hydrolysis and HPLC separation of kinins, 10.3 pg BK and 7.3 pg T-kinin/mg protein.

The role of the kallikrein-kinin system in joint inflammatory disease.

Components of kallikrein-kininogen-kinin are activated in response to noxious stimuli (chemical, physical or bacterial), which may lead to excessive release of kinins in the synovial joints that may produce inflammatory joint disease. The inflammatory changes observed in synovial tissue may be due to activation of B2 receptors. Kinins also stimulate the synthesis of other pro-inflammatory agents (PGs, LTs, histamine, EDRF, PGI2 and PAF) in the inflamed joint. B2 receptor antagonists may provide valuable new analgesic drugs. The mode of excessive kinin release in inflamed synovial joints leads to stimulation of pro-inflammatory actions of B2 kinin receptors. These properties could be antagonized by novel B2 receptor antagonists (see Fig. 4). Further, it is suggested that substances directed to reduce the activation of KKS may provide a pharmacological basis for the synthesis of novel antirheumatic or anti-inflammatory drugs.

Experimental approach to a role of the increased T-kininogen level in carrageenin-induced pleurisy of rats.

In order to elucidate the biological role of T-kininogen, it's levels in plasma, exudate, and liver were measured by radioimmunoassay in rats following the induction of carrageenin pleurisy. T-kininogen level in the liver microsomes was increased markedly at 8-24 hr after the carrageenin injection, and its plasma level increased at 24-48 hr with a delay. Pretreatment with dexamethasone suppressed the pleural exudate accumulation almost completely, but inhibited the T-kininogen level in plasma or liver only partially. When rats were pretreated with carrageenin injection into a paw 2 days prior to intrapleural injection of carrageenin, the pretreatment did not affect the pleurisy development, even though the plasma level of T-kininogen was greatly increased. Increased level of T-kininogen correlated well with the thiol protease inhibitor activity found in the plasma and exudate. These results indicate that an increase in the T-kininogen level does not influence the exudation, but might act as an inhibitor of thiol proteases that could be released at the inflammatory site.

Proteinase-sensitive regions in the heavy chain of low molecular weight kininogen map to the inter-domain junctions.

Low molecular weight kininogen from human plasma was subjected to limited proteolysis with trypsin, chymotrypsin, elastase, and bromelain, and the resulting fragments of 20,000 or 40,000 Da were isolated. Amino-terminal sequence analysis of the fragments disclosed for the various proteinases eight independent cleavage sites distinct from the typical kallikrein cleavage sites flanking the kinin region. All the identified cleavage sites cluster in two stretches of 11-12 residues of the kininogen heavy chain. These short segments represent the primary attack sites for proteinases ("proteinase-sensitive regions") in the heavy chain portion of human low molecular weight kininogen. The amino acid sequences of the two proteinase-sensitive regions are mutually homologous; they are further characterized by the presence of a single copy each of the consensus tetrapeptide Cys-X-Gly-Cys known to form a narrow disulfide loop (Kellermann, J., Thelen, C., Lottspeich, F., Henschen, A., Vogel, R., and Müller-Esterl, W. (1987) Biochem. J. 247, 15-21). The proteinase-sensitive regions are located at the junctions of the three cystatin-like domains constituting the kininogen heavy chain. Proteolytic cleavage at the sensitive regions dissects the kininogen heavy chain and releases single domains of 20,000 Da and combined domains of 40,000 Da which can function as cysteine proteinase inhibitors. The presence of kininogen heavy chain domains in plasma samples under pathologic conditions suggests that cleavage of the proteinase-sensitive regions might also occur in vivo.

[Effect of kontrikal on the kinin system of the lymph and blood in anaphylactic shock]. / Vliianie kontrikala na kininovuiu sistemu limfy i krovi pri anafilakticheskom shoke.

A study was made of the effect of contrykal, a nonspecific inhibitor of the trypsin-plasmin-kallikrein system on the time course of kininogens and free kinins in the lymph of the thoracic duct and blood. Experiments were performed on 42 guinea-pigs with anaphylactic shock. It was demonstrated that anaphylactic shock was accompanied by the activation of the blood and lymph kinin system, manifesting in a decrease in the bradykininogen level and a rise in the content of free kinins in both body fluids. Pretreatment with contrykal did not avert the development of anaphylactic shock but significantly reduced the pronounced manifestations of the clinical picture and exerted an inhibitory action on the activation of the kallikrein-kinin system of the blood and lymph.

Activation of plasma kallikrein-kinin system and its significant role in pleural fluid accumulation of rat carrageenin-induced pleurisy.

Rat pleurisy was induced by intrapleural injection of lambda-carrageenin. The pleural exudate began to be accumulated 1-3 h after carrageenin administration and showed a peak at 19 h. The levels of prekallikrein and high-molecular-weight (HMW), but not low-molecular-weight (LMW), kininogen in the pleural fluid were markedly decreased when compared with those in plasma. Prekallikrein in rat plasma was activated by incubation with carrageenin in vitro. Captopril increased the plasma exudation significantly at 1-5 h. Depletion of prekallikrein and HMW kininogen in rat plasma by preadministration of bromelain caused marked inhibition of the plasma exudation at 1-24 h. The rest of the plasma exudation after bromelain was further decreased by simultaneous pretreatment of rats with both bromelain and aspirin. These results clearly indicate that plasma prekallikrein was activated in the pleural cavity and bradykinin released was responsible for plasma exudation during the entire course of this pleurisy.