Kinin B1 receptor blockade attenuates hepatic fibrosis and portal hypertension in chronic liver diseases in mice.

BACKGROUND AND AIMS: Kinin B1 receptors (B1Rs) are implicated in the pathogenesis of fibrosis. This study examined the anti-fibrotic effects of B1R blockade with BI 113823 in two established mouse models of hepatic fibrosis induced by intraperitoneal carbon tetrachloride (CCl4) injection or bile duct ligation (BDL). The mechanisms underlying the protection afforded by B1R inhibition were examined using human peripheral blood cells and LX2 human hepatic stellate cells (HSCs). METHODS: Fibrotic liver diseases were induced in mice by intraperitoneal carbon tetrachloride (CCl4) injection for 6 weeks, and by bile duct ligation (BDL) for 3 weeks, respectively. Mice received daily treatment of vehicle or BI 113823 (B1R antagonist) from onset of the experiment until the end of the study. RESULTS: B1Rs were strongly induced in fibrotic mouse liver. BI 113823 significantly attenuated liver fibrosis and portal hypertension (PH), and improved survival in both CCl4 and BDL mice. BI 113823 significantly reduced the expression of fibrotic proteins α-SMA, collagens 1, 3, 4, and profibrotic growth factors PDGF, TGFß, CTGF, VEGF, proliferating cell nuclear antigen; and reduced hepatic Akt phosphorylation in CCl4- and BDL-induced liver fibrosis. BI 113823 also reduced expression of Cytokines IL-1, IL-6; chemokines MCP-1, MCP-3 and infiltration of inflammatory cells; and inhibited human monocyte and neutrophil activation, transmigration, TNF-α & MPO production in vitro. BI 113823 inhibited TGF-ß and B1R agonist-stimulated human-HSC activation, contraction, proliferation, migration and fibrosis protein expression, and inhibited activation of PI3K/Akt signalling pathway. CONCLUSIONS: B1Rs merits consideration as a novel therapeutic target for chronic liver fibrosis and PH.

Tissue kallikrein-kinin therapy in hypertension and organ damage.

Tissue kallikrein is a serine proteinase that cleaves low molecular weight kininogen to produce kinin peptides, which in turn activate kinin receptors to trigger multiple biological functions. In addition to its kinin-releasing activity, tissue kallikrein directly interacts with the kinin B2 receptor, protease-activated receptor-1, and gamma-epithelial Na channel. The tissue kallikrein-kinin system (KKS) elicits a wide spectrum of biological activities, including reducing hypertension, cardiac and renal damage, restenosis, ischemic stroke, and skin wound injury. Both loss-of-function and gain-of-function studies have shown that the KKS plays an important endogenous role in the protection against health pathologies. Tissue kallikrein/kinin treatment attenuates cardiovascular, renal, and brain injury by inhibiting oxidative stress, apoptosis, inflammation, hypertrophy, and fibrosis and promoting angiogenesis and neurogenesis. Approaches that augment tissue kallikrein-kinin activity might provide an effective strategy for the treatment of hypertension and associated organ damage.

Impact of kinins in the treatment of cardiovascular diseases.

In recent years, ACE Inhibitors (ACEIs) and Angiotensin II receptor antagonists (also known as AT1 receptor antagonists (AT1-RAs), angiotensin receptor blockers (ARBs), or Sartans), have become the drugs of choice for the treatment of hypertension, heart and renal failure, coronary artery diseases, myocardial infarction and diabetes. By suppressing angiotensin and potentiating bradykinin effects, ACEIs and ARBs activate hemodynamic, metabolic and cellular mechanisms that not only reduce high blood pressure, but also protect the endothelium, the heart, the kidney and the brain, namely the target organs which are at risk in cardiovascular diseases. Major therapeutic benefits of these drugs are the reduction of cardiovascular events and the amelioration of the quality of life and of the patient survival. Results from large clinical trials have established that ACEIs and ARBs are efficient and safe drugs, suitable for the chronic treatments of cardiovascular diseases. Side effects are rare and easily manageable in most cases. The following is a brief review of the basic actions and mechanisms by which two opposing systems, the renin-angiotensin (RAS) and the kallikrein-kinin (KKS), interact in the regulation of cardiovascular and fluid homeostasis to keep the balance in healthy life and correct the imbalance in pathological conditions. Here we discuss how and why imbalances created by overactive RAS are best corrected by treatments with ACEI or AT1-RAs.

Towards drug discovery for brain tumours: interaction of kinins and tumours at the blood brain barrier interface.

Cancers of the brain are intrinsically more complicated to treat than systemic malignancies due to the unique anatomical features of the brain. The blood-brain barrier prevents chemotherapeutic agents from reaching brain neoplasms, and angiogenesis occurs as the metabolic needs of the tumour increase, thus further complicating treatment. The newly formed blood vessels form the blood-tumour barrier and are distinct from the blood-brain barrier in that they are more permeable. Being more permeable, these abnormal blood vessels lead to the formation of peri-tumoural edema, which is the cause of much morbidity and mortality associated with central nervous system neoplasms. While the cause of the increased permeability is unclear, kinins have been implicated in regulating the permeability of normal vasculature. Kinins are also known to exert many inflammatory actions affecting both normal and angiogenic blood vessels, as well as tumour cells. The vasodilatory and vascular permeabilizing effects of kinins, and particularly bradykinin and substance P, have been investigated with regard to delivery of chemotherapeutic agents to neoplastic brain tissue through both vascular barriers. In contrast, kinin receptor antagonists have been found to exert effects on tumour cells that result in decreased angiogenesis, tumour cell motility and growth. Thus, many recent patents describe kinin activity on brain vasculature, which may play an integral role in the development of treatments for malignancies in the central nervous system through amelioration of angiogenesis. In conjunction, patents that discuss the ability of kinins to decrease tumour cell migration and proliferation demonstrate that kinins may offer novel approaches to brain tumour therapy in the future.

Tissue kallikrein and kinin infusion rescues failing myocardium after myocardial infarction.

BACKGROUND: Tissue kallikrein is a serine proteinase that generates the vasoactive kinin peptide, which produces vasodilatory, angiogenic, and antiapoptotic effects. In this study, we investigated the effect of a stable supply of kallikrein and kinin on ventricular remodeling and blood vessel growth in rats after myocardial infarction. METHODS AND RESULTS: At 1 week after coronary artery ligation, tissue kallikrein or kinin was infused through a minipump for 4 weeks. At 5 weeks after myocardial infarction, kallikrein and kinin infusion significantly improved cardiac contractility and reduced diastolic dysfunction without affecting systolic blood pressure. Kallikrein and kinin infusion significantly increased capillary density in the noninfarcted region. Kallikrein and kinin infusion also reduced heart weight/body weight ratio, cardiomyocyte size, and atrial natriuretic peptide and brain natriuretic peptide expression in the noninfarcted area. Moreover, kallikrein and kinin infusion inhibited interstitial collagen deposition, collagen fraction volume, and collagen I and collagen III mRNA levels, transforming growth factor (TGF)-beta1 and plasminogen activator inhibitor-1 expression, and Smad2 phosphorylation. The effects of kallikrein and kinin on cardiac remodeling were associated with increased nitric oxide levels and reduced NADPH oxidase expression and activity, superoxide formation, and malondialdehyde levels. Furthermore, in cultured cardiac fibroblasts, kinin inhibited angiotensin II-stimulated TGF-beta1 production, and the effect was blocked by icatibant. CONCLUSION: These results indicate that a subdepressor dose of kallikrein or kinin can restore impaired cardiac function in rats with postinfarction heart failure by inhibiting hypertrophy and fibrosis and promoting angiogenesis through increased nitric oxide formation and suppression of oxidative stress and TGF-beta1 expression.

Kinins and cardiovascular diseases.

Kinins are synthesized from their precursors by different enzymes and participate in the regulation of cardiovascular function through bradykinin (BK) B1 and B2 receptors. They modulate blood coagulation by exerting antithrombotic and profibrinolytic actions. By activating B2 receptors that results in the release of nitric oxide and prostacyclin, kinins inhibit vascular smooth muscle growth and neointima formation, which may play an inhibitory role on the atherosclerosis development, while through the activation of B1 receptors, they may play a deleterious role in this disease. Kinins are potent endogenous vasodilators that are involved in the regulation of coronary vascular tone. However, due to their metabolic characteristics, these peptides act mainly as an autocrine/paracrine factor to locally regulate blood perfusion of organs. By modulating cellular energy metabolism and myocardial oxygen consumption, they protect cardiac and vascular endothelial function in myocardial ischemia and heart failure. Finally, mounting evidence indicates that kinins are involved in the actions of some drugs actually used in the treatment of cardiovascular diseases such as angiotensin-converting enzyme inhibitors and angiotensin AT1 receptor antagonists. Taken together, the kinin system constitutes a potential therapeutic target for cardiovascular diseases. Experiments in animals attempted to explore the kinin system as a therapeutic means, including the mobilization of endogenous kinins using pharmacological agents, searching BK analogs with long-acting properties and gene therapies. However, the potential values of the kinin system have not been taken into consideration in clinical practice for cardiovascular indications.

Kallikrein/kinin protects against gentamicin-induced nephrotoxicity by inhibition of inflammation and apoptosis.

BACKGROUND: Our previous study showed that kallikrein gene transfer protects against gentamicin-induced nephrotoxicity and enhances renal function. In this study, we investigated the effects and potential mechanisms of kallikrein/kinin on inflammation and apoptosis induced by gentamicin. METHODS: Rats were injected subcutaneously with gentamicin daily for 10 days and received an intravenous injection of adenovirus carrying the human tissue kallikrein gene or control virus on the first day of gentamicin administration. RESULTS: After 10 days of gentamicin treatment, kallikrein gene transfer significantly attenuated gentamicin-induced tubular dilatation and lumenal protein casts. Moreover, kallikrein gene transfer reduced monocyte/macrophage infiltration, monocyte chemoattractant peptide-1 expression and renal cell apoptosis. Kallikrein's protective effects were accompanied by increased nitric oxide formation, and reduced NADH oxidase activity and superoxide production. Suppression of oxidative stress was associated with diminished c-jun N-terminal kinase activation and intercellular adhesion molecule-1 and transforming growth factor-beta protein levels. These biochemical effects were blocked by icatibant, indicating a kinin B2 receptor-mediated signalling event. CONCLUSIONS: This study indicates that kallikrein/kinin protects against gentamicin-induced nephrotoxicity by inhibiting inflammatory cell recruitment and apoptosis through suppression of oxidative stress-mediated signalling pathways. These findings raise the potential of applying kallikrein therapy approaches in treating aminoglycoside-induced renal damage.

The kallikrein-kinin system: from mediator of inflammation to modulator of cardioprotection.

Kinin is an important mediator of hyperalgesia, inflammatory conditions and asthma. It causes pain, inflammation, increased vascular permeability and vasodilatation. Several kinin antagonists have been developed with the aim of treating these pathologies. Kinin B2 receptor agonists and kallikrein may have clinical utility in the treatment of hypertension, left ventricular hypertrophy, ischemic heart disease, congestive heart failure and diabetes. However, there is a need to know whether there is a safe therapeutic window between potential cardio-protective and pro-inflammatory effects following administration of kinin B2 receptor agonists.

Kinins and endothelial control of vascular smooth muscle.

Plasma and vascular kinins stimulate the production of endothelium-derived nitric oxide, prostacyclin and hyperpolarizing factor (which regulates the function of vascular smooth muscle), and endothelial interactions with blood cells. The role of kinins in vasomotion is determined by the rate of production of the peptides by kininogenases and their degradation by kininases, in particular angiotensin-converting enzyme (ACE). Acute increases in plasma kinin levels during exercise or myocardial ischemia indicate that the metabolism of the peptides is fine tuned to the systemic or local metabolic demands. The release of endothelial vasodilators is impaired (or counterbalanced by the release of chemical or functional antagonists) in atherosclerosis, hypertension, diabetes, subarachidonic hemorrhage, and following postischemic injury. ACE-inhibitors potentiate the action of kinins and normalize endothelial function. In septic shock, hypotension triggered by overproduction of kinins leads to cardiovascular impairment and end-organ damage. Thus the balance in the metabolism of kinins modulates the control of blood flow by the endothelium.

[Kinin B1 and B2 receptor antagonists and therapeutic perspectives]. / Antagonistes de récepteurs B1 et B2 des kinines et perspectives thérapeutiques.

Physiological and pathological effects of kinins result from the activation of specific receptors which are present in various organs. Kinin receptors have been characterized through studies on isolated organs in vitro and have been classified as B1 and B2. A careful analysis of B2 receptors led to the identification of two subtypes, namely B2rb (in the rabbit) and B2gp (in the guinea-pig). The distinction between B2rb and B2gp receptors is primarily based on differences in the activities of selective agonists and particularly on differences in affinities of competitive antagonists, namely DArg[Hyp3,DPhe7,Leu8]BK and the non-peptide compound, WIN 64338. The non-competitive antagonist, HOE 140, has shown the same affinity on B2rb and B2gp. The potential role of B1 and B2 receptors in physiopathology is analysed on data obtained with specific and selective antagonists of the B1 (desArg9[Leu8]BK) and B2 (HOE140) receptors. The therapeutic potential of endogenous kinins as mediators of the therapeutic beneficial effects of the angiotensin-converting enzyme inhibitors or the potential of the use of exogenous kinins in the vascular permeability are discussed together with the therapeutic potential of B1 and B2 receptor antagonists.

Kinin/prostaglandin system: its therapeutic value in surgical stress.

Multiple system organ failure as a consequence of injury or sepsis remains the major reason for death in critically ill patients. One of the treatment concepts that has recently attracted clinical attention is the administration of kinins and prostaglandins (PGs). On the basis of experimental data, there is reason to believe that these compounds may have the potential to manipulate favorably certain processes and mechanisms (such as inflammatory or ischemic reactions) thought to be important in the pathophysiology of surgical stress. However, thus far, information on those effects in humans is still scarce. On the other hand, administration of kinins and PGs is technically possible and can be performed safely, even in intensive care patients. Therefore, different techniques, effects, and side-effects of kinin/PG therapy deserve clinical testing. It remains to be seen whether this concept will be useful in the treatment of critically ill surgical patients.

In vitro growth inhibition of human small cell lung cancer by physalaemin.

Production and secretion of neuroendocrine peptides by small cell lung cancer (SCLC) has been detected in the past years. Most recently the role of bombesin as an autocrine/paracrine growth modifier has been demonstrated. We used the soft agarose clonogenic assay to evaluate the influence of other neuroendocrine peptides on the in vitro proliferation of SCLC cell lines. Neuroendocrine peptides tested were adrenocorticotropic hormone, arginine vasopressin, calcitonin, glucagon, kassinin, neurotensin, physalaemin, somatostatin, and substance P. Experiments were carried out in serum-free and serum-supplemented media with and without serum-free incubation periods. Our results indicated that the amphibian undecapeptide physalaemin inhibits the clonal and mass culture growth of SCLC cell lines at picomolar concentrations. All other neuroendocrine peptides failed to influence SCLC growth in the test systems used. These results suggest a growth regulating effect of physalaemin and a potential new form of neuroendocrine peptide therapy for SCLC.

[Special indications for the use of soft contact lenses as a drug-release-system (author's transl)]. / Besondere Indikationen für die Anwendung weicher Kontaktlinsen als Augentropfenreservoir (Drug Release System)

Research has been performed, both experimentally and clinically, to establish the value of the association of soft contact lenses and some types of eye drops. The use of soft contact lenses with eye drops may be useful in some special cases: a) more prolonged and more sustained effect compared with the usual way of administration of eye drops (especially antiglaucomatous substances, antimetabolites, mydriatics); b) possibility of reducing the concentration to avoid local discomfort or systemic side-effects, without loss of their effectiveness on the eye conditions to be treated. The combined use of soft lenses (12.5-15 mm in diameter) with eye drops may be obtained either by presoaking the lens in the liquid or by regular instillation of eye drops after insertion of the lens; the two techniques may of course be associated. In the present research the advantages of utilizing hydrophylic lenses with osmotically active substances, to obtain a better and more protracted dehydration of the cornea, were first examined, in vitro and in vivo. The following substances were tested: 10% propylenglycol, 10% glycerol, 10% glucose and 5% natrium chloride. The clearing effect of the different types of treatment was evaluated in 45 patients with edematous bullous keratopathy with an instrument which measured the infrared light emitted by an optic fiber and reflected by the cornea. The effects were more marked for the epithelial than for the stromal oedema. Another group of investigations was performed with two polypeptides with high molecular weight: Eledoisin, extracted from a mediterranean octopus, Eledone moschata, and Physalaemin, extracted from the skin of a south american batrachian, Physalaemus fuscomaculatus, both of these stimulate the lacrimal secretion and were previously successfully employed topically by the authors against keratoconjunctivitis sicca. The increase of the amount of fluid was however short-lived. Eledoisin at a concentration of 200 mug/ml, was examined in its effects both in vitro and in vivo, whereas physalaemin, at a concentration of 20 mug/ml, only in vitro, owing to the present shortage of the product. The clinical tests in 23 eyes of 14 patients with keratoconjunctivitis sicca proved satisfactory, since the lacrymal stimulating effect is not only greater, but lasts three times longer by combining the instillation of eledoisin with a presoaked soft lens. Some antiglaucomatous products (propranolol, clonidine, prostigmine) were, finally, used in association with a soft lens to reduce the concentration of the eye drops for a better tolerance locally (propranolol: a beta-adrenergic blocking agent) or generally (clonidine: alpha-adrenergic agent), also with the advantage of protracted release. With propranolol the concentration could be reduced to 0.01-0,10% (instead of 0.125 to 0.25%) and to 1.5% (instead of 3%) with prostigmine, when lenses were presoaked or instillations took place at regular time intervals, after insertion of the lenses.