Selective plasma kallikrein inhibitor attenuates acute intestinal inflammation in Lewis rat

The Plasma Kallikrein-Kininogen Pathway Is Critical in the Pathogenesis of Colitis in Mice

The kallikrein-kinin system (KKS) consists of two serine proteases, prekallikrein (pKal) and factor XII (FXII), and a cofactor, high-molecular-weight kininogen (HK). Upon activation of the KKS, HK is cleaved to release bradykinin. Although the KKS is activated in humans and animals with inflammatory bowel disease (IBD), its role in the pathogenesis of IBD has not been characterized. In the present study, we determined the role of the KKS in the pathogenesis of IBD using mice that lack proteins involved in the KKS. In two colitis models, induced by dextran sulfate sodium (DSS) or 2,4,6-trinitrobenzene sulfonic acid (TNBS), mice deficient in HK, pKal, or bradykinin receptors displayed attenuated phenotypes, including body weight loss, disease activity index, colon length shortening, histological scoring, and colonic production of cytokines. Infiltration of neutrophils and inflammatory monocytes in the colonic lamina propria was reduced in HK-deficient mice. Reconstitution of HK-deficient mice through intravenous injection of HK recovered their susceptibility to DSS-induced colitis, increased IL-1β levels in the colon tissue and bradykinin concentrations in plasma. In contrast to the phenotypes of other mice lacking other proteins involved in the KKS, mice lacking FXII had comparable colonic inflammation to that observed in wild-type mice. The concentration of bradykinin was significantly increased in the plasma of wild-type mice after DSS-induced colitis. In vitro analysis revealed that DSS-induced pKal activation, HK cleavage, and bradykinin plasma release were prevented by the absence of pKal or the inhibition of Kal. Unlike DSS, TNBS-induced colitis did not trigger HK cleavage. Collectively, our data strongly suggest that Kal, acting independently of FXII, contributes to experimental colitis by promoting bradykinin release from HK.

The Gut-Kidney Axis: Putative Interconnections Between Gastrointestinal and Renal Disorders

Diabetic kidney disease (DKD) is a devastating condition associated with increased morbidity and premature mortality. The etiology of DKD is still largely unknown. However, the risk of DKD development and progression is most likely modulated by a combination of genetic and environmental factors. Patients with autoimmune diseases, like type 1 diabetes, inflammatory bowel disease, and celiac disease, share some genetic background. Furthermore, gastrointestinal disorders are associated with an increased risk of kidney disease, although the true mechanisms have still to be elucidated. Therefore, the principal aim of this review is to evaluate the impact of disturbances in the gastrointestinal tract on the development of renal disorders.

A review on chemical-induced inflammatory bowel disease models in rodents

Ulcerative colitis and Crohn's disease are a set of chronic, idiopathic, immunological and relapsing inflammatory disorders of the gastrointestinal tract referred to as inflammatory bowel disorder (IBD). Although the etiological factors involved in the perpetuation of IBD remain uncertain, development of various animal models provides new insights to unveil the onset and the progression of IBD. Various chemical-induced colitis models are widely used on laboratory scale. Furthermore, these models closely mimic morphological, histopathological and symptomatical features of human IBD. Among the chemical-induced colitis models, trinitrobenzene sulfonic acid (TNBS)-induced colitis, oxazolone induced-colitis and dextran sulphate sodium (DSS)-induced colitis models are most widely used. TNBS elicits Th-1 driven immune response, whereas oxazolone predominantly exhibits immune response of Th-2 phenotype. DSS-induced colitis model also induces changes in Th-1/Th-2 cytokine profile. The present review discusses the methodology and rationale of using various chemical-induced colitis models for evaluating the pathogenesis of IBD.

Modulation of the coagulation system during severe streptococcal disease

Haemostasis is maintained by a tightly regulated coagulation system that comprises platelets, procoagulant proteins, and anticoagulant proteins. During the local and systemic response to bacterial infection, the coagulation system becomes activated, and contributes to the pathophysiological response to infection. The significant human pathogen, Streptococcus pyogenes has multiple strategies to modulate coagulation. This can range from systemic activation of the intrinsic and extrinsic pathway of coagulation to local stimulation of fibrinolysis. Such diverse effects on this host system imply a finely tuned host-bacteria interaction. The molecular mechanisms that underlie this modulation of the coagulation system are discussed in this review.

Intestinal tissue kallikrein-kinin system in inflammatory bowel disease

Tissue kallikrein cleaves kininogens to release kinins. Kinins mediate inflammation by activating constitutive bradykinin receptor-2 (BR2), which are rapidly desensitized, and induced by inflammatory cytokines bradykinin receptor-1 (BR1), resistant to desensitization. Intestinal tissue kallikrein (ITK) may hydrolyze growth factors and peptides, whereas kinins are responsible for capillary permeability, pain, synthesis of cytokines, and adhesion molecule-neutrophil cascade. Our and others results have demonstrated ITK in intestinal goblet cells and its release into interstitial space during inflammation. Kallistatin, an inhibitor of ITK, has been shown in epithelial and goblet cells, and was decreased in inflamed intestine as well as in plasma compared with noninflammatory controls. BR1 was upregulated in patients with inflammatory bowel disease (IBD), and it has expressed in an apical part of enterocytes in inflamed intestine, but in the basal part in normal intestine. ITK and BR1 were visualized in macrophages forming granuloma in Crohn's disease. In animal studies BR2 blockade decreased intestinal contraction, but had limited effect on inflammatory lesions. BR1 was found to be upregulated in animal inflamed intestine, in part dependent on tumor necrosis factor alpha (TNF-α). A selective BR1 receptor antagonist decreased morphological and biochemical features of experimental intestinal inflammation. Both BR1 and BR2 mediate epithelial ion transport that leads to secretory diarrhea. The upregulation of BR1 in inflamed intestine provides a structural basis for the kinins function, suggesting that a selective BR1 antagonist may have potential in therapeutic trial of IBD patients.

The role of the complement and contact systems in the dextran sulfate sodium-induced colitis model: the effect of C1 inhibitor in inflammatory bowel disease

The complement and contact systems may be involved in the pathophysiological process of inflammatory bowel disease (IBD). C1 inhibitor (C1INH) is the most important inhibitor of both the complement and contact systems. We evaluated the role of these systems and the effect of both active and inactive forms of C1INH (iC1INH) in dextran sulfate sodium (DSS)-induced colitis mouse model. Three percent DSS was used in drinking water to induce colitis in complement C3-deficient (C3(-/-)) mice, bradykinin type 2 receptor deficient (Bk(2)R(-/-)) mice, and C57BL/6 mice. After ten days DSS exposure, C3(-/-) mice exhibited markedly less weight loss than wild-type (WT) mice (12 +/- 3.3% vs. 30 +/- 1.2%, P < 0.05) and developed a milder disease-activity index (DAI), histological score, colon shortening, and myeloperoxidase (MPO) elevation (P < 0.05, respectively). The Bk(2)R(-/-) mice were not protected from the disease. Seven-day treatment with either native C1INH or iC1INH reduced the severity of the disease in WT mice, as indicated by decreased weight loss (15 +/- 1.8%, 14 +/- 2.1% vs. 30 +/- 1.2%, P < 0.05, respectively), DAI, intestinal tissue damage, and MPO elevation compared with untreated WT DSS control mice (P < 0.05, respectively). These findings suggest that complement plays a role in the development of DSS-induced colitis and that blockade of the complement system might be useful for the acute phase of IBD treatment. C1INH, however, leads to an amelioration of DSS-induced colitis via a mechanism that does not involve the inhibition of complement or contact system activation but does result in significant suppression of leukocyte infiltration.

The role of plasma high molecular weight kininogen in experimental intestinal and systemic inflammation

Inflammation is accompanied by activation of the plasma kallikrein-kinin system (KKS). KKS activation has been demonstrated in a variety of inflammatory human diseases. To further explore the participation of KKS in arthritis and inflammatory bowel disease, we used two experimental animal models in arthritis and enterocolitis. We found that activation of KKS is associated with arthritis induced by intraperitoneal injection of peptidoglycan-polysaccharide polymers (PG-PS) as well as the enterocolitis and systemic inflammation induced also by PG-PS when injected into the intestinal wall of genetically susceptible Lewis rats. We postulated that KKS participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion, and release of proteases. We demonstrated that therapy with a specific plasma kallikrein inhibitor modulated the experimental enterocolitis, arthritis, and systemic inflammation. The fact that deficiency of plasma high molecular weight kininogen in the genetically susceptible Lewis rat results in decreased chronic enterocolitis and systemic inflammation also supports our hypothesis. We suggest that KKS plays a similar role in idiopathic human intestinal inflammatory disease and arthritis, making kallikrein-kinin system proteins appealing targets for drug therapy in chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease.

The role of plasma high molecular weight kininogen in experimental intestinal and systemic inflammation

Inflammation is accompanied by activation of the plasma kallikrein-kinin system (KKS). KKS activation has been demonstrated in a variety of inflammatory human diseases. To further explore the participation of KKS in arthritis and inflammatory bowel disease, we used two experimental animal models in arthritis and enterocolitis. We found that activation of KKS is associated with arthritis induced by intraperitoneal injection of peptidoglycan-polysaccharide polymers (PG-PS) as well as the enterocolitis and systemic inflammation induced also by PG-PS when injected into the intestinal wall of genetically susceptible Lewis rats. We postulated that KKS participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion, and release of proteases. We demonstrated that therapy with a specific plasma kallikrein inhibitor modulated the experimental enterocolitis, arthritis, and systemic inflammation. The fact that deficiency of plasma high molecular weight kininogen in the genetically susceptible Lewis rat results in decreased chronic enterocolitis and systemic inflammation also supports our hypothesis. We suggest that KKS plays a similar role in idiopathic human intestinal inflammatory disease and arthritis, making kallikrein-kinin system proteins appealing targets for drug therapy in chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease.

Immunolocalization and expression of kinin B1R and B2R receptors in human inflammatory bowel disease

Bradykinin is a mediator of inflammation, responsible for pain, vasodilation, and capillary permeability. Bradykinin receptor 1 (B(1)R) and bradykinin receptor 2 (B(2)R) are G protein-coupled receptors that mediate kinin effects. The latter is constitutive and rapidly desensitized; the former is induced by inflammatory cytokines and resistant to densensitization. The distribution of bradykinin receptors in human intestinal tissue was studied in patients with inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD). Both B(2)R and B(1)R proteins are expressed in the epithelial cells of normal and IBD intestines. B(1)R protein is visualized in macrophages at the center of granulomas in CD. B(2)R protein is normally present in the apexes of enterocytes in the basal area and intracellularly in inflammatory tissue. In contrast, B(1)R protein is found in the basal area of enterocytes in normal intestine but in the apical portion of enterocytes in inflamed tissue. B(1)R protein is significantly increased in both active UC and CD intestines compared with controls. In patients with active UC, B(1)R mRNA is significantly higher than B(2)R mRNA. However, in inactive UC patients, the B(1)R and B(2)R mRNA did not differ significantly. Thus bradykinin receptors in IBD may reflect intestinal inflammation. Increased B(1)R gene and protein expression in active IBD provides a structural basis of the important role of bradykinin in chronic inflammation.

A monoclonal antibody against kininogen reduces inflammation in the HLA-B27 transgenic rat

The human leukocyte antigen B27 (HLA-B27) transgenic rat is a model of human inflammatory bowel disease, rheumatoid arthritis and psoriasis. Studies of chronic inflammation in other rat models have demonstrated activation of the kallikrein–kinin system as well as modulation by a plasma kallikrein inhibitor initiated before the onset of clinicopathologic changes or a deficiency in high-molecular-mass kininogen. Here we study the effects of monoclonal antibody C11C1, an antibody against high-molecular-mass kininogen that inhibits the binding of high-molecular-mass kininogen to leukocytes and endothelial cells in the HLA-B27 rat, which was administered after the onset of the inflammatory changes. Thrice-weekly intraperitoneal injections of monoclonal antibody C11C1 or isotype IgG₁ were given to male 23-week-old rats for 16 days. Stool character as a measure of intestinal inflammation, and the rear limbs for clinical signs of arthritis (tarsal joint swelling and erythema) were scored daily. The animals were killed and the histology sections were assigned a numerical score for colonic inflammation, synovitis, and cartilage damage. Administration of monoclonal C11C1 rapidly decreased the clinical scores of pre-existing inflammatory bowel disease (P < 0.005) and arthritis (P < 0.001). Histological analyses confirmed significant reductions in colonic lesions (P = 0.004) and synovitis (P = 0.009). Decreased concentrations of plasma prekallikrein and high-molecular-mass kininogen were found, providing evidence of activation of the kallikrein–kinin system. The levels of these biomarkers were reversed by monoclonal antibody C11C1, which may have therapeutic potential in human inflammatory bowel disease and arthritis.

A monoclonal antibody to high-molecular weight kininogen is therapeutic in a rodent model of reactive arthritis

We reported that high-molecular weight kininogen is proangiogenic by releasing bradykinin and that a monoclonal antibody to high-molecular weight kininogen, C11C1, blocked its binding to endothelial cells. We now test if this antibody can prevent arthritis and systemic inflammation in a Lewis rat model. We studied 32 animals for 16 days. Group I (negative control) received saline intraperitoneally. Group II (disease-treated) received peptidoglycan-polysaccharide simultaneously with C11C1. Group III (disease-untreated) received peptidoglycan-polysaccharide simultaneously with isotype-matched mouse IgG. Group IV (disease-free-treated) and group V (disease-free isotype-treated) received saline and C11C1 or mouse IgG. Analysis of joint diameter changes showed a decrease in the C11C1 disease-treated group compared to the disease-untreated group. The hind paw inflammatory score showed a decrease in the intensity and extent of inflammation between the disease-untreated and the C11C1 disease-treated group. Prekallikrein, high-molecular weight kininogen, factor XI, and factor XII were decreased in the disease-untreated group compared to the C11C1 disease-treated group. T-kininogen was increased in the disease-untreated group when compared with the C11C1 disease-treated group. Disease-free groups IV and V did not show any sign of inflammation at any time. This study shows that monoclonal antibody C11C1 attenuates plasma kallikrein-kinin system activation, local and systemic inflammation, indicating therapeutic potential in reactive arthritis.

Remission of rosacea induced by reduction of gut transit time

Rosacea is a chronic disorder characterized by hypersensitivity of the facial vasculature, presenting with intense flushing eventually leading to chronic erythema and telangiectasia. Although the precise aetiology of rosacea is not known, numerous associations with inflammatory gastrointestinal tract disorders have been reported. Furthermore, substance P-immunoreactive neurones occur in considerably greater numbers in tissue surrounding affected blood vessels suggesting involvement of neurogenic inflammation and moreover plasma kallikrein-kinin activation is consistently found in patients. In this report, a patient without digestive tract disease is described, who experienced complete remission of rosacea symptoms following ingestion of a material intended to sweep through the digestive tract and reduce transit time below 30 h. It is possible that intestinal bacteria are capable of plasma kallikrein-kinin activation and that flushing symptoms and the development of other characteristic features of rosacea result from frequent episodes of neurogenic inflammation caused by bradykinin-induced hypersensitization of facial afferent neurones. The possible relevance of this hypothesis to other conditions featuring afferent hypersensitivity, such as fibromyalgia, is considered.

The mutation Ser511Asn leads to N-glycosylation and increases the cleavage of high molecular weight kininogen in rats genetically susceptible to inflammation

Crohn disease is immunologically mediated and characterized by intestinal and systemic chronic inflammation. In a rat model, injection of peptidoglycan-polysaccharide complexes into the intestinal wall induced chronic inflammation in Lewis but neither Fischer nor Buffalo rats, indicating a differential genetic susceptibility. Proteolysis of plasma high molecular weight kininogen (HK) yielding bradykinin and cleaved HK (HKa) was faster in Lewis than in Fischer or Buffalo rat plasma. A single point mutation at nucleotide 1586 was found translating from Ser511 (Buffalo and Fisher) to Asn511 (Lewis). The latter defines an Asn-Xaa-Thr consensus sequence for N-glycosylation. We expressed these domains in Escherichia coli and found no differences in the rate of cleavage by purified kallikrein in the 3 strains in the absence of N-glycosylation. We then expressed these domains in Chinese hamster ovary (CHO) cells, which are capable of glycosylation, and found an increased rate of cleavage of Lewis HK. The Lewis mutation is associated with N-glycosylation as evidenced by a more rapid migration after treatment with N-glycosidase F. When CHO cells were cultured in the presence of tunicamycin, the kallikrein-induced cleavage rate of Lewis HK was not increased. This molecular alteration might be one contributing factor resulting in chronic inflammation in Lewis rats.

Intestinal tissue kallikrein-kallistatin profile in inflammatory bowel disease

The profile of tissue kallikrein (TK) and its inhibitor, kallistatin was evaluated in patients with active ulcerative colitis (UC) and Crohn's disease (CD). Tissue kallikrein is mainly localized to goblet cells and kallistatin to epithelial cells of human intestine. Intestinal tissue kallikrein (ITK) and kallistatin are significantly decreased in inflamed intestine compared to noninflammatory controls. TK mRNA as well as kallistatin mRNA is significantly decreased in intestinal biopsy samples from UC-active patients compared with controls. The difference in distribution and levels of ITK and kallistatin in protein and mRNA in patients with inflammatory bowel disease (IBD) compared to controls suggest a role in inflammatory state.

Chronic intestinal inflammation and angiogenesis in genetically susceptible rats is modulated by kininogen deficiency

Genetically susceptible Lewis rats injected in the intestinal wall with peptidoglycan-polysaccharide (PG-APS) polymers develop chronic granulomatous enterocolitis associated with activation of the kallikrein-kinin system. To elucidate the role of high-molecular-weight kininogen (HK), we backcrossed Brown Norway rats having an HK deficiency with Lewis rats for five generations. Two new strains were produced, wild-type F5 (F5WT) and HK deficient (F5HKd), each with a approximately 97% Lewis genome. The HK values of F5WT rat plasma and F5HKd rat plasma were 0.62 +/- 0.20 and 0.08 +/- 0.03 U/ml, respectively. Among the inflammatory changes, the mean gross gut, total intestinal histologic and liver granuloma score and the white blood count were significantly lower in the F5HKd than the F5WT rats. Plasma T-kininogen was significantly less in F5HKd. Angiogenesis (mean vascular density) in the cecum was decreased significantly in F5HKd compared to F5WT. These results indicate the importance of the kallikrein-kinin system in this model of chronic enterocolitis and systemic inflammation.

Suppression of dextran sulfate sodium-induced colitis in kininogen-deficient rats and non-peptide B2 receptor antagonist-treated rats

Various proinflammatory mediators are believed to be involved in the processes and symptoms of ulcerative colitis (UC). To determine whether endogenous kinin enhances the severity of UC, we induced experimental colitis (EC) in kininogen-deficient mutant rats and tested the effect of a non-peptide B2 receptor antagonist. EC was induced in male kininogen-deficient Brown Norway-Katholiek rats (BN-Ka) and normal Brown Norway-Kitasato rats (BN-Ki) with 5% dextran sulfate sodium (DSS). Sprague-Dawley rats (SD) were also used. Colon length, body weight and hematocrit were determined for 7 days. Effects of FR173657, an orally active B2 antagonist, were tested. The colon length was shortened in BN-Ki with DSS treatment, but not in BN-Ka, and the difference between their lengths was significant. The hematocrit value was also reduced in BN-Ki, and the difference in hematocrit between BN-Ki and BN-Ka was significant. In SD, shortening of the colon and reduction in hematocrit were also observable, and both were blunted by FR173657. The survival rate in SD given DSS for 7 days was 68%, but FR173657 treatment restored it significantly to 100%. These results suggest that the endogenous kinins generated from the kallikrein-kinin system have a significant role in the development of EC.

Kallikrein-kinin system activation in Crohn's disease: differences in intestinal and systemic markers

OBJECTIVES

Observations in experimental models and in human ulcerative colitis suggest that activation of the kallikrein-kinin system plays a role in the pathogenesis of inflammatory bowel disease. The aim of this study was to assess activation of the plasma and tissue kallikrein-kinin system in Crohn's disease.

METHODS

We studied plasma inflammatory and contact system parameters in 36 patients with Crohn's disease and in 36 control subjects with noninflammatory GI diseases. We also obtained tissue samples from the involved intestine of 12 patients with Crohn's disease, and from normal peritumoral tissue (12 patients) and diverticulitis tissue (seven patients) as controls. Full-thickness sections were tested for intestinal tissue kallikrein reactivity with a specific antibody.

RESULTS

In Crohn's disease patients and controls, plasma levels of prekallikrein, factor XI, high molecular weight kininogen and its cleaved form were normal. Crohn's disease patients had significantly higher levels of antigen and functional Cl-inhibitor (+22%, +12%) than did controls (p = 0.005, p = 0.004). After surgical resection, antigen and functional Cl-inhibitor significantly decreased in Crohn's disease patients (-22%, -15%; p = 0.035, p = 0.006). Intestinal tissue kallikrein immunoreactivity was absent (75%) or weak (25%) in the goblet cells from Crohn's disease tissue sections but was normal in controls, with a highly significant difference in the staining score (p = 0.0001). Intestinal tissue kallikrein immunoreactivity in the interstitium was higher in Crohn's disease than in normal and diverticulitis samples (p = 0.0001 and p = 0.001, respectively).

CONCLUSIONS

Our observations suggest that intestinal tissue kallikrein is involved in the inflammatory process in Crohn's disease. The lack of contact system activation in peripheral blood might be related to the high plasma levels of Cl-inhibitor, the most important inhibitor of the contact system in the circulation.

Kininogen deficiency modulates chronic intestinal inflammation in genetically susceptible rats

Genetically susceptible Lewis rats injected in the intestinal wall with peptidoglycan-polysaccharide (PG-APS) polymers develop chronic granulomatous enterocolitis concomitant with activation of the kallikrein-kinin system. To elucidate the role of high-molecular-weight kininogen (HK) in chronic enterocolitis, we back crossed Brown-Norway rats having a HK deficiency with Lewis rats for five generations. Two new strains were produced, wild-type F5 (F5WT) and HK deficient (F5HKd), each with a approximately 97% Lewis genome. The HK values of F5WT and F5HKd rat plasma were 0.62 +/- 0.20 and 0.08 +/- 0.03 U/ml, respectively. In PG-APS-injected rats, chronic inflammation was measured by using gross gut score, histological inflammation, liver granuloma, and white blood cell count. The mean gross gut scores were significantly lower in the F5HKd than in the F5WT rats. Plasma T-kininogen was significantly less in F5HKd. These results indicate the importance of the kallikrein-kinin system in this model of chronic enterocolitis and systemic inflammation.

Serum angiotensin I-converting enzyme is reduced in Crohn's disease and ulcerative colitis irrespective of genotype

OBJECTIVES

Crohn's disease (CD) is recognized to be a vascular endothelial-associated disease. Angiotensin I-converting enzyme (ACE) exists mainly in endothelial cells. There are some reports on serum ACE levels in patients with CD, but the ACE level is still controversial. Recently, genetic control of serum ACE levels by ACE gene polymorphisms (classified as II, ID, and DD) has been suggested. Although we must consider such polymorphisms to elucidate ACE levels in patients with CD, there is no report about this.

METHODS

We studied 341 healthy controls (male/female = 178/162), 39 patients with CD (31/8), 43 patients with ulcerative colitis (UC) (22/21) and 19 patients with infectious enterocolitis (8/11). The polymorphism in intron 16 of the ACE gene was examined by PCR. Serum ACE levels were measured by the method of Kasahara.

RESULTS

Serum ACE levels in patients with CD and UC were significantly lower than in healthy controls, irrespective of the genotype of ACE (genotype II: CD 7.0+/-2.5 [mean +/- SD], UC 7.1+/-3.3, controls 11.8+/-2.9, genotype ID: CD 9.7+/-4.1, UC 11.4+/-4.6, controls 15.2+/-3.6, genotype DD: CD 13.9+/-5.8, UC 10.7+/-3.6, controls 19.3+/-3.9 IU/L, controls vs CD, UC; p < 0.01, 0.05). However, there was no significant difference in serum ACE levels between CD and UC.

CONCLUSIONS

Considering ACE gene polymorphism, serum ACE levels in patients with inflammatory bowel disease are lower than in controls. Serum ACE levels reflect a part of the pathogenesis of inflammatory bowel disease.

The kallikrein-kininogen-kinin system: lessons from the quantification of endogenous kinins

The purpose of the present review is to describe the place of endogenous kinins, mainly bradykinin (BK) and des-Arg(9)-BK in the kallikrein-kininogen-kinin system, to review and compare the different analytical methods reported for the assessment of endogenous kinins, to explain the difficulties and the pitfalls for their quantifications in biologic samples and finally to see how the results obtained by these methods could complement and extend the pharmacological evidence of their pathophysiological role.

Plasma and tissue kallikrein in arthritis and inflammatory bowel disease

To ascertain the participation of the plasma kallikrein-kinin system (KKS) in arthritis and inflammatory bowel disease, we used two rat models resembling rheumatoid arthritis and Crohn's disease. Proteoglycan-polysaccharide from group A streptococcus (PG-APS) produced chronic destructive inflammation and systemic response in the genetically susceptible Lewis rat, in the joints when injected intraperitoneally and in the bowel when injected into the gut wall. In both models, the KKS is activated, as evidenced by decreased prekallikrein, factor XI and high molecular weight kininogen. A specific plasma kallikrein inhibitor, Bz-Pro-Phe-boroarginine, reverses the plasma changes as well as the clinical gross and microscopic pathology of both the experimental arthritis and the inflammatory bowel disease in the genetically susceptible rats. We have also shown that the tissue kallikrein system is involved in the intestinal inflammatory changes. Intestinal tissue kalikrein (ITK) is localized in goblet cells in both normal and inflamed tissue. In chronic granulomatous inflammation, ITK is localized in macrophages. ITK decreases in chronic inflammation, probably due to secretion, since the mRNA is unchanged. Kallikrein binding protein, the ITK inhibitor, decreases due to enzyme-inhibitor complexes. Both plasma and tissue kallikrein are appealing targets for drug therapy of rheumatoid arthritis and Crohn's disease.

Localization and secretion of tissue kallikrein in peptidoglycan-induced enterocolitis in Lewis rats

The plasma kallikrein-kinin system is a mediator of intestinal inflammation induced by peptidoglycan-polysaccharide from group A streptococci (PG-APS) in rats. In this study we investigated the participation of intestinal tissue kallikrein (ITK). Lewis rats were injected intramurally with PG-APS. ITK was visualized by immunohistochemical staining. Cecal ITK concentration was measured by radioimmunoassay, and gene expression was evaluated by RNase protection assay. Kallikrein-binding protein (KBP) was evaluated in plasma by ELISA. Tissue kallikrein was identified in cecal goblet cells in both control and PG-APS-injected rats and in macrophages forming granulomas in inflamed tissues. Cecal ITK was significantly lower in acute and chronic phases of inflammation and in supernatant from in vitro cultures of inflamed cecum. ITK mRNA levels were not significantly different. Plasma KBP levels were significantly reduced in inflamed rats. The presence of tissue kallikrein in macrophages suggests participation in experimental colitis. The decrease of ITK in the inflamed intestine associated with unchanged mRNA levels suggests ITK release during intestinal inflammation.

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.