Activity of several carbohydrate exchange enzymes in the lymph during fever reaction

This work includes a comparative study of aldolase enzyme activity, LDG and its isoenzymes in thoracic duct lymph and blood serum of rabbits in fever reaction dynamics of various duration. Irrespective of its duration the fever was followed by a significant activation of investigated enzymes in the body liquids. However, in many day fever reaction a rise of LDG level in the lymph was more prolonged then that in the blood. The above studies make it possible to assume that the released enzymes in fever reaction are primarily resorbed by lymphatic capillaries and their activity indices in the blood serum are largely evidenced by the transport function of the lymphatic system.     

The influence of drugs on the kinin-forming system in relation to pregnancy and parturition in the rat.

The duration of normal gestation and parturition in the rat can be changed by treatment with drugs which alter the equilibrium of the kallikrein-kinin system. The kallikrein inhibitor, aprotinin, when given from Days 19-22 of pregnancy prolongs gestation. Treatment with aprotinin from Days 20-22 of pregnancy prolongs the parturient process, as does a single dose given on the morning of Day 22. Kallikrein, when administered from Days 19-22 of pregnancy, results in a prolongation of gestation and abolishes the pre-parturient behaviour ('labour'). Parturition is prolonged and many fetuses are stillborn. Soya bean trypsin inhibitor when given from Days 19-22 of pregnancy delays and prolongs parturition; maternal haemorrhage occurs during birth and many fetuses are born dead or are abandoned at birth. It is suggested that the kallikrein-kinin system plays a functional role in the normal process of parturition in the rat.     

Transferase contents in lymph and blood in fever reaction]

The aim of the present investigation was the study of the content of alanine, asparagine-transaminases, gamma-glutamyl transferase and their isoenzymes, as well as leucine aminotransferase in the lymph of thoracic duct, hepatic and intestinal lymph and peripheral blood in dynamics of fever reaction of various duration in the experiments on rabbits. Irrespective of its duration, the fever was followed by a significant activation of the enzymes in the body fluids. However, in many-day fever reaction, a rise of enzymes level in the lymph was more prolonged than that in the blood. The above studies make it possible to assume that the released enzymes in fever reaction are primarily resorbed by lymphatic capillaries and their activity indices in the blood serum are largely evidenced by the transport function of the lymphatic system.     

Identification and characterization of a new kallikrein-kinin system inhibitor from the salivary glands of the malaria vector mosquito Anopheles stephensi

A new kallikrein-kinin system inhibitor, designated anophensin, was identified in the salivary glands of the malaria vector mosquito, Anopheles stephensi. In vitro reconstitution experiments showed that anophensin inhibits activation of the kallikrein-kinin system by inhibiting the reciprocal activation of factor XII (FXII) and prekallikrein (PK), and subsequent release of bradykinin. Additionally, anophensin inhibits activation of the kallikrein-kinin system on cultured human umbilical vein endothelial cells (HUVECs). Direct binding assays show that this inhibitory effect is due to Zn(2+)-dependent specific binding of anophensin to both FXII and high molecular weight kininogen (HK). Furthermore, anophensin interacts with both the N-terminus of FXII and domain D5 of HK, which are the binding domains for biological activating surfaces. These results suggest that anophensin inhibits activation of the kallikrein-kinin system by interfering with the association of FXII and HK with biological activating surfaces, resulting in the inhibition of bradykinin release in a host animal during insect blood-feeding.     

What have we learned about the kallikrein-kinin and renin-angiotensin systems in neurological disorders?

The kallikrein-kinin system(KKS) is an intricate endogenous pathway involved in several physiological and pathological cascades in the brain. Due to the pathological effects of kinins in blood vessels and tissues, their formation and degradation are tightly controlled. Their components have been related to several central nervous system diseases such as stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy and others. Bradykinin and its receptors(B1R and B2R) may have a role in the pathophysiology of certain central nervous system diseases. It has been suggested that kinin B1R is up-regulated in pathological conditions and has a neurodegenerative pattern, while kinin B2R is constitutive and can act as a neuroprotective factor in many neurological conditions. The renin angiotensin system(RAS) is an important blood pressure regulator and controls both sodium and water intake. AngⅡ is a potent vasoconstrictor molecule and angiotensin converting enzyme is the major enzyme responsible for its release. AngⅡ acts mainly on the AT1 receptor, with involvement in several systemic and neurological disorders. Brain RAS has been associated with physiological pathways, but is also associated with brain disorders. This review describes topics relating to the involvement of both systems in several forms of brain dysfunction and indicates components of the KKS and RAS that have been used as targets in several pharmacological approaches.     

Role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension

The role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension was studied using mutant kininogen-deficient Brown-Norway Katholiek (BN-Ka) rats, which generate no kinin in their urine, and other hypertensive rat models. It was found that ingestion of a low sodium diet or infusion of NaCl in doses slightly above 0.15 M caused hypertension and sodium accumulation in erythrocytes and the cerebrospinal fluid of kininogen-deficient BN-Ka rats. Development of hypertension in the deoxycorticosterone-acetate-salt model was completely prevented by administration of a newly discovered inhibitor, ebelactone B, of carboxypeptidase Y-like exopeptidase (an urinary kininase). The urinary kallikrein excretion of spontaneously hypertensive rats was lower than that of Wistar Kyoto rats at 4 weeks of age and did not increase by administration of furosemide, a diuretic agent, although approximately 50% of the diuretic action of this agent was dependent upon the renal kallikrein-kinin system in normal rats. In conclusion, the renal kallikrein-kinin system works as a safety valve for excess sodium intake.     

Vascular permeability enhancement by Vibrio mimicus protease and the mechanisms of action.

Vibrio mimicus, a causative agent of gastroenteritis, has also been reported to attribute to extraintestinal infections. Recently we have purified a metalloprotease produced by the pathogen: however, the role of the protease in V. mimicus infection has not been documented. The V. mimicus protease (VMP) was found to enhance vascular permeability and form edema when injected into the dorsal skin of guinea pig and rat. The permeability enhancement by VMP was observed in a dose-dependent manner in both guinea pig and rat skin. In guinea pig, an inhibitor of the angiotensin-converting enzyme was found to augment the permeability enhancement reaction. The permeability enhancement was significantly blocked by soybean trypsin inhibitor (SBTI), an inhibitor of plasma kallikrein reaction. In vitro conversion of plasma prekallikrein to kallikrein by VMP was also noted. In rat skin, the permeability enhancement reaction was not blocked by antihistamine or SBTI. However, the reaction was partially blocked when a mixture of antihistamine and SBTI was administered with VMP. It is apparent from the study that in guinea pig skin, VMP enhances vascular permeability through activation of plasma kallikrein-kinin system which generates bradykinin, whereas in addition to the activation of plasma kallikrein-kinin cascade in the case of rat, stimulation of histamine release from mast cells and other unknown mechanism seem to be also a cause of the permeability enhancement reaction. These results suggest that VMP may play a role in extraintestinal infections with edema caused by the pathogen.     

Contribution of the N-terminal and C-terminal domains of haemaphysalin to inhibition of activation of plasma kallikrein-kinin system

Haemaphysalin is a kallikrein-kinin system inhibitor from hard tick Haemaphysalis longicornis, and consists of two Kunitz type protease inhibitor domains. Each domain as well as haemaphysalin inhibited intrinsic coagulation by inhibiting activation of the kallikrein-kinin system without affecting the amidolytic activities of intrinsic coagulation factors, indicating that both domains were involved in the inhibition through a similar mechanism to that for haemaphysalin. Reconstitution experiments showed that the C-terminal domain contributed more predominantly to this inhibition. Direct binding assaying showed that the C-terminal domain could bind to the cell-binding region of high molecular weight kininogen (HK), suggesting that it also binds to the cell-binding region of factor XII. Judging from these findings, the C-terminal domain may more effectively inhibit the association of factor XII and HK with the cell surface by binding to cell-binding regions, and hence would predominantly contribute to the inhibition of activation of the kallikrein-kinin system.     

Identification and characterization of plasma kallikrein-kinin system inhibitors from salivary glands of the blood-sucking insect Triatoma infestans

Two plasma kallikrein-kinin system inhibitors in the salivary glands of the kissing bug Triatoma infestans, designated triafestin-1 and triafestin-2, have been identified and characterized. Reconstitution experiments showed that triafestin-1 and triafestin-2 inhibit the activation of the kallikrein-kinin system by inhibiting the reciprocal activation of factor XII and prekallikrein, and subsequent release of bradykinin. Binding analyses showed that triafestin-1 and triafestin-2 specifically interact with factor XII and high molecular weight kininogen in a Zn2+-dependent manner, suggesting that they specifically recognize Zn2+-induced conformational changes in factor XII and high molecular weight kininogen. Triafestin-1 and triafestin-2 also inhibit factor XII and high molecular weight kininogen binding to negatively charged surfaces. Furthermore, they interact with both the N-terminus of factor XII and domain D5 of high molecular weight kininogen, which are the binding domains for biological activating surfaces. These results suggest that triafestin-1 and triafestin-2 inhibit activation of the kallikrein-kinin system by interfering with the association of factor XII and high molecular weight kininogen with biological activating surfaces, resulting in the inhibition of bradykinin release in an animal host during insect blood-feeding.     

The kallikrein-kinin system in the colon and lung fluid from a cribriform degeneration (cri) mutant mouse

The cribriform degeneration (cri) mutant mouse was widely studied in regard to the electrolyte and kallikrein metabolism because of its potentiality as a cystic fibrosis (CF) genetic animal model. In this paper the activity of the kallikrein-kinin system, and the kininase activity and glycoproteins concentration in colon and pulmonary lavage fluid (PLF) in homozygous mutant (cri/cri) and control sibling mice are described. The mutant mice showed a diminished kininogenase and kininase activity and glycoproteins concentrations in both studied organs. It is concluded that a kallikrein-kinin system alteration could be responsible of the cri/cri electrolyte defect.     

Kallikrein-kinin system in hepatic experimental models

The purpose of this brief review is to describe some characteristics of the kallikrein-kinin system (KKS) in the liver. The liver synthesizes kininogens and prekallikrein and the synthesis of both proteins is increased in rats during the acute phase reaction. It is also the main organ to clear tissue as well as plasma kallikrein from the circulation in normal and pathological conditions. Bradykinin (BK), yielded by the kallikrein-kinin system, is a potent arterial hypotensive peptide, but in the liver it induces a portal hypertensive response. The portal hypertensive action of bradykinin is mediated by B2 receptors located on sinusoidal cells of the periportal region and is followed by its hydrolysis by angiotensin-converting enzyme, which is primarily present in the perivenous (centrolobular) region.     

Specificity comparison of a serine endopeptidase (SH1) and a serine thiol endopeptidase (STH2) purified from human urine

In this study, we compared the properties of a serine endopeptidase H1 (SH1) and a serine thiol endopeptidase (STH2) purified from human urine by DEAE-cellulose followed by a Bio Gel A0.5 m or Sepharose Mercurial chromatographs. These enzymes differ in their action upon different hormone peptides. We used fluorogenic substrates to further characterize the enzyme. The substrate specificity of urinary SH1 was studied using different internally quenched fluorescent peptides, and AbzFGQEDDnp was hydrolyzed by SH1. Other enzymes present in urine, such as serine endopeptidase H2, prolyl endopeptidase, neutral endopeptidase like and angiotensin-I converting enzyme, were not able to hydrolyze this substrate. SH1 is 100% inhibited by PMSF and resistant to EDTA, OPA, thiorphan, E64, pOHMB and phosphoramidon. Endopeptidase STH2 is completely inhibited by PMSF, E64 and pOHMB. Enzyme SH1 hydrolyzes the peptide bound F5-S6 at bradykinin (BK: RPPGFSPFR) molecule and R-Q at AbzBKQEDDnp. When studying enzyme STH2, the cleavage sites determined to the related substrates were F5-S6 using BK as substrate and F-R using AbzBKQEDDnp. The kilometers value obtained for AbzBKQEDDnp and AbzFGQEDDnp were 1.18 and 0.007 uM, respectively. Kininases from kidney and urine can hydrolyze peptide bounds from components of the kallikrein-kinin system, the angiotensin-renin system and the neuropeptides system, straight contributing in kidney homeostasis. SH1 was located at the distal tubule [Casarini et al., 1999a, Am. J. Physiol. 277, F66] and can have an important function in the control of kinin found in this portion, since is known that all components of the kallikrein-kinin system were found in this portion. The physiological role of SHT2 could be related to the inter-relation between the kallikrein-kinin system and neuropeptides in the control of the water electrolyte balance [Braz. J. Med. Biol. Res. 25 (3) (1992) 219].     

Photopheresis: a new therapeutic concept

Photopheresis, the process by which peripheral blood is exposed in an extracorporeal flow system to photoactivated 8-methoxypsoralen (8-MOP), is a new treatment for disorders caused by aberrant T lymphocytes. It is now a standard therapy for advanced cutaneous T-cell lymphoma and shows promise in the treatment of two autoimmune disorders, pemphigus vulgaris and progressive systemic sclerosis (scleroderma). Additional diseases for which clinical trials are in progress include multiple sclerosis, organ transplant rejection, rheumatoid arthritis, and AIDS. The mechanism of action appears to involve a "vaccination" against the pathogenic T cells, in a clone-specific manner. Photoactivated 8-MOP initiates a cascade of immunologic events by forming covalent photoadducts with nuclear and cell surface-adherent DNA and possibly with other cellular molecules. For reasons not yet fully clarified, but probably related to enhanced cycling of the T-cell receptor for antigen, photopheresis increases the immunogenicity of the irradiated T cells so that their reinfusion induces a therapeutically significant immunologic reaction that targets unirradiated T cells of the pathogenic clone(s). The specificity of the induced immunologic reaction probably results from the extremely disproportionate expansion of the pathogenic clone(s), relative to the several million other clones of normal T cells.     

Kallikrein-kinin in stem cell therapy

The tissue kallikrein-kinin system exerts a wide spectrum of biological activities in the cardiovascular, renal and central nervous systems. Tissue kallikrein-kinin modulates the proliferation, viability, mobility and functional activity of certain stem cell populations, namely mesenchymal stem cells(MSCs), endothelial progenitor cells(EPCs), mononuclear cell subsets and neural stem cells. Stimulation of these stem cells by tissue kallikrein-kinin may lead to protection against renal, cardiovascular and neural damage by inhibiting apoptosis, inflammation, fibrosis and oxidative stress and promoting neovascularization. Moreover, MSCs and EPCs genetically modified with tissue kallikrein are resistant to hypoxia- and oxidative stress-induced apoptosis, and offer enhanced protective actions in animal models of heart and kidney injury and hindlimb ischemia. In addition, activation of the plasma kallikrein-kinin system promotes EPC recruitment to the inflamed synovium of arthritic rats. Conversely, cleaved high molecular weight kininogen, a product of plasma kallikrein, reduces the viability and vasculogenic activity of EPCs. Therefore, kallikrein-kinin provides a new approach in enhancing the efficacy of stem cell therapy for human diseases.     

Peptide inhibitors of converting enzyme.

Human plasma and atypical lung converting enzyme, and porcine plasma converting enzyme are substantially inhibited by other components of the renin-angiotensin system, and by angiotensin II and its analogues. Des-Asp¹ angiotensin II (angiotensin III) 0.1 mM and tridecapeptide renin substrate 0.1 mM are both effective inhibitors of human lung, plasma and porcine plasma converting enzymes. Des-Asp¹-Arg² angiotensin II also was an effective inhibitor of plasma enzymes. Bradykininase activity (kininase II) of the converting enzymes was also inhibited by angiotensin I, angiotensin III, tetradecapeptide renin substrate and tridecapeptide renin substrate. The substantial kininase and converting enzyme inhibitory effects of components of the renin-angiotensin system, suggest a potential close physiologic relationship between the kallikrein-kinin system and the renin-angiotensin system.     

Molecular mechanisms of filovirus cellular trafficking

The filoviruses, Ebola and Marburg, are two of the most pathogenic viruses, causing lethal hemorrhagic fever in humans. Recent discoveries suggest that filoviruses, along with other phylogenetically or functionally related viruses, utilize a complex mechanism of replication exploiting multiple cellular components including lipid rafts, endocytic compartments, and vacuolar protein sorting machinery. In this review, we summarize these recent findings and discuss the implications for vaccine and therapeutics development.     

Characteristics of neural and humoral systems involved in the regulation of blood pressure in snakes

Cardiovascular function is affected by many mechanisms, including the autonomic system, the kallikrein-kinin system (KKS), the renin-angiotensin system (RAS) and the endothelin system. The function of these systems seems to be fairly well preserved throughout the vertebrate scale, but evolution required several adaptations. Snakes are particularly interesting for studies related to the cardiovascular function because of their elongated shape, their wide variation in size and length, and because they had to adapt to extremely different habitats and gravitational influences. To keep the normal cardiovascular control the snakes developed anatomical and functional adaptations and interesting structural peculiarities are found in their autonomic, KKS, RAS and endothelin systems. Our laboratory has characterized some biochemical, pharmacological and physiological properties of these systems in South American snakes. This review compares the components and function of these systems in snakes and other vertebrates, and focuses on differences found in snakes, related with receptor or ligand structure and/or function in autonomic system, RAS and KKS, absence of components in KKS and the intriguing identity between a venom and a plasma component in the endothelin system.     

Studies of four Japanese families with hereditary angioneurotic edema: simultaneous activation of plasma protease systems and exogenous triggering stimuli

Forty-five relatives of 4 families with hereditary angioneurotic edema (HANE) were studied. Twenty-five, including 11 asymptomatic kindreds with the disposition, showed typical changes in complement system compatible with HANE. Follow-up study of HANE patients showed that, even in remission period, complement, coagulation and fibrinolytic systems can be activated. During edema attacks, moderate haemoconcentration and neutrophilia were encountered and kallikrein-kinin system was found to be also activated. Replacement therapy with C 1-inhibitor preparation for an edema attack revealed that clinical improvement paralleled the increase in blood levels of high molecular weight kininogen. Thus, HANE attack is considered to be elicited in kindreds with the hereditary disposition by activation of plasma protease systems, particularly by that of kallikrein-kinin system. On the other hand, exogenous triggers that can initiate activation of the protease systems can be classified into 2, neuro-humoral (sympathetic nerve response) and physico-chemical, categories. Hence, the edema attack of kindreds with the hereditary disposition can at least be modified by the biosynthesis of plasma factors and the individual susceptibility to the liberated catecholamines. These two different reaction processes are considered to be linked by the release of plasminogen activator and/or Hageman factor activating enzyme.