Kallikrein-kinin system in hepatic experimental models

Human plasma kallikrein: roles in coagulation, fibrinolysis, inflammation pathways, and beyond

Human plasma kallikrein (PKa) is obtained by activating its precursor, prekallikrein (PK), historically named the Fletcher factor. Human PKa and tissue kallikreins are serine proteases from the same family, having high- and low-molecular weight kininogens (HKs and LKs) as substrates, releasing bradykinin (Bk) and Lys-bradykinin (Lys-Bk), respectively. This review presents a brief history of human PKa with details and recent observations of its evolution among the vertebrate coagulation proteins, including the relations with Factor XI. We explored the role of Factor XII in activating the plasma kallikrein-kinin system (KKS), the mechanism of activity and control in the KKS, and the function of HK on contact activation proteins on cell membranes. The role of human PKa in cell biology regarding the contact system and KSS, particularly the endothelial cells, and neutrophils, in inflammatory processes and infectious diseases, was also approached. We examined the natural plasma protein inhibitors, including a detailed survey of human PKa inhibitors' development and their potential market.

Effect of Kinins on the Hepatic Oxidative Stress in Mice Treated with a Methionine-Choline Deficient Diet

Non-alcoholic fatty liver is the leading cause of hepatic disease worldwide and ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) due to cell injury, oxidative stress, and apoptosis. The kinins' role in the liver has been studied in experimental fibrosis, partial hepatectomy, and ischemia-reperfusion and is related to cell death and regeneration. We investigated its role in experimental NASH induced by a methionine-choline deficient diet for 4 weeks. After that, liver perfusion was performed, and bradykinin (BK) or des-Arg9-BK was infused. Cell death was evaluated by cathepsin-B and caspase-3 activity and oxidative stress by catalase (CAT), glutathione S-transferase, and superoxide dismutase (SOD) activities, as well as malondialdehyde and carbonylated proteins. In control livers, DABK increased CAT activity, which was reversed by antagonist DALBK. In the NASH group, kinins tend to decrease antioxidant activity, with SOD activity being significantly reduced by BK and DABK. Malondialdehyde levels increased in all NASH groups, but carbonylated protein did not. DABK significantly decreased cathepsin-B in the NASH group, while caspase-3 was increased by BK in control animals. Our results suggest that B1R and/or B2R activation did not induce oxidative stress but affected the antioxidant system, reducing SOD in the NASH group.

Reduced hepatic bradykinin degradation accounts for cold-induced BAT thermogenesis and WAT browning in male mice

An important role for liver in the regulation of adipose tissue thermogenesis upon cold exposure has been suggested; however, the underlying mechanisms remain incompletely defined. Here, we identify elevated serum bradykinin levels in response to acute cold exposure in male mice. A bolus of anti-bradykinin antibodies reduces body temperature during acute cold exposure, whereas bradykinin has the opposite effect. We demonstrate that bradykinin induces brown adipose tissue thermogenesis and white adipose tissue browning, and bradykinin increases uncoupling protein 1 (UCP1) expression in adipose tissue. The bradykinin B2 receptor (B2R), adrenergic signaling and nitric oxide signaling are involved in regulating bradykinin-increased UCP1 expression. Moreover, acute cold exposure inhibits hepatic prolyl endopeptidase (PREP) activity, causing reduced liver bradykinin degradation and increased serum bradykinin levels. Finally, by blocking the breakdown of bradykinin, angiotensin-converting enzyme inhibitors (ACEIs) increase serum bradykinin levels and induce brown adipose tissue thermogenesis and white adipose tissue browning via B2R. Collectively, our data provide new insights into the mechanisms underlying organ crosstalk in whole-body physiology control during cold exposure and also suggest bradykinin as a possible anti-obesity target.

Diagnostic and prognostic role of circulating neutrophil extracellular trap markers and prekallikrein in patients with high-grade serous ovarian cancer

Objective

Tumor-promoting inflammation is among the hallmarks of cancer. Prekallikrein is among the acute-phase reactants in the inflammatory response; moreover, neutrophils release nuclear contents into the extracellular space to create neutrophil extracellular traps (NET). We aimed to investigate the diagnostic and prognostic utilities of circulating plasma NET markers and prekallikrein for high-grade serous ovarian cancer (HGSOC).

Methods

Circulating levels of three NET markers (histone-DNA complex, cell-free DNA, and neutrophil elastase) and prekallikrein were measured in 75 patients with HGSOC and 23 healthy controls. We used an area under the receiver operating characteristic curve (AUC) analysis to investigate their diagnostic and prognostic utilities for HGSOC.

Results

Compared with healthy controls, patients with HGSOC showed significantly higher levels of the three NET markers and prekallikrein. Patients with advanced-stage HGSOC showed significantly higher levels of the cell-free DNA (87.4 vs. 79.5 ng/ml; P = 0.013), compared with those with early-stage HGSOC. Further, the levels of histone-DNA complex, neutrophil elastase, and prekallikrein did not significantly differ according to the cancer stage. All markers showed significant diagnostic utility. Notably, a logistic regression-based model that comprised all four markers showed the strongest diagnostic power (AUC, 0.966; 95% confidence interval [CI], 0.933-1.000). Specifically, neutrophil elastase was identified as an independent poor prognostic factor for overall survival (adjusted hazard ratio [aHR], 10.17; 95% CI, 1.09-94.97; P = 0.042) and progression-free survival (aHR, 14.47; 95% CI, 1.52-137.35; P = 0.020) in patients with HGSOC.

Conclusions

The levels of the three NET markers and prekallikrein might be novel diagnostic and prognostic markers for HGSOC.

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, TGFβ, 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-β 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.

Elevated extracellular trap formation and contact system activation in acute leukemia

Leukemic cells release their nuclear contents into the extracellular space upon activation. The released nuclear contents, called extracellular traps, can activate the contact system of coagulation. This study accessed the extent of contact system activation, the levels of extracellular traps, and coagulation activation in hematologic malignancies including acute leukemia. In 154 patients with hematologic malignancies (acute leukemia, n = 29; myelodysplastic syndrome, n = 20; myeloproliferative neoplasms, n = 69; plasma cell myeloma, n = 36) and 48 normal controls, the levels of coagulation factors (fibrinogen and factor VII, VIII, IX, and XII), D-dimer, thrombin generation, extracellular trap markers (histone-DNA complex, cell-free dsDNA, leukocyte elastase), and contact system markers (activated factor XII [XIIa], high-molecular-weight kininogen, prekallikrein, bradykinin) were measured. Patients with acute leukemia showed the highest levels of peak thrombin, extracellular trap markers, and factor XIIa. Factor XIIa level was significantly associated with the presence of acute leukemia. The histone-DNA complex and cell-free dsDNA were revealed as significant associated factors with the factor XIIa level. Three markers of extracellular traps and two markers of thrombin generation significantly contributed to the hemostatic abnormalities in hematologic malignancies. Contact system was activated in acute leukemia and its activation was significantly associated with the extent of extracellular trap formation. This finding suggests that extracellular traps might be a major source of contact system activation and therapeutic strategies targeting extracellular trap formation or contact system activation may be beneficial in acute leukemia.

Contact system activation and high thrombin generation in hyperthyroidism

BACKGROUND

Hyperthyroidism is associated with increased thrombotic risk. As contact system activation through formation of neutrophil extracellular traps (NET) has emerged as an important trigger of thrombosis, we hypothesized that the contact system is activated along with active NET formation in hyperthyroidism and that their markers correlate with disease severity.

SUBJECTS AND METHODS

In 61 patients with hyperthyroidism and 40 normal controls, the levels of coagulation factors (fibrinogen, and factor VII, VIII, IX, XI and XII), D-dimer, thrombin generation assay (TGA) markers, NET formation markers (histone-DNA complex, double-stranded DNA and neutrophil elastase) and contact system markers (activated factor XII (XIIa), high-molecular-weight kininogen (HMWK), prekallikrein and bradykinin) were measured.

RESULTS

Patients with hyperthyroidism showed higher levels of fibrinogen (median (interquartile range), 315 (280-344) vs 262 (223-300), P = 0.001), D-dimer (103.8 (64.8-151.5) vs 50.7 (37.4-76.0), P < 0.001), peak thrombin (131.9 (102.2-159.4) vs 31.6 (14.8-83.7), P < 0.001) and endogenous thrombin potential (649 (538-736) vs 367 (197-1147), P = 0.021) in TGA with 1 pM tissue factor, neutrophil elastase (1.10 (0.39-2.18) vs 0.23 (0.20-0.35), P < 0.001), factor XIIa (66.9 (52.8-87.0) vs 73.0 (57.1-86.6), P < 0.001), HMWK (6.11 (4.95-7.98) vs 3.83 (2.60-5.68), P < 0.001), prekallikrein (2.15 (1.00-6.36) vs 1.41 (0.63-2.22), P = 0.026) and bradykinin (152.4 (137.6-180.4) vs 118.3 (97.1-137.9), P < 0.001) than did normal controls. In age- and sex-adjusted logistic regression analysis, fibrinogen, factor VIII, IX and XIIa, D-dimer, peak thrombin, neutrophil elastase, HMWK and bradykinin showed significant odds ratios representing hyperthyroidism's contribution to coagulation and contact system activation. Free T4 was significantly correlated with factors VIII and IX, D-dimer, double-stranded DNA and bradykinin.

CONCLUSION

This study demonstrated that contact system activation and abundant NET formation occurred in the high thrombin generation state in hyperthyroidism and were correlated with free T4 level.

Factor XII-mediated contact activation related to poor prognosis in disseminated intravascular coagulation

BACKGROUND

The contact system that initiates the intrinsic coagulation pathway plays a role in thrombus formation. Since neutrophil extracellular traps (NET), which are mainly composed of histone and DNA, are actively formed in disseminated intravascular coagulation (DIC) and the NET can activate factor XII, it is plausible that a NET component strongly activates the contact system in patients with DIC.

METHODS

In 146 patients suspected of having DIC, the plasma levels of contact system factors including factor XII, activated factor XII (XIIa), prekallikrein, high-molecular-weight kininogen (HMWK), bradykinin, extrinsic factor VII and histone–DNA complex were measured. In an in vitro plasma clotting assay, factor XII–deficient plasma was stimulated with silica or histone.

RESULTS

The levels of not only extrinsic coagulation factor VII but also intrinsic coagulation factors including factors XI and XII were significantly decreased in patients with overt DIC in comparison with those with no overt DIC. Factor XIIa and histone-DNA complex were also significantly increased in patients with overt DIC. However,HMWK, prekallikrein and bradykin inw ere not significantly different between patients with and without overt DIC. Interestingly, factors XII and XIIa were revealed as significantly independent potential prognostic markers for DIC. The histone-DNA complex level significantly contributed to the factor XIIa level (20.6%). In an in vitro clotting assay, histone, a major component of NET, activated coagulation that was dependent, in part, on the presence of factor XII.

CONCLUSION

These findings suggest that active NET formation can induce factor XII-mediated coagulation activation in patients with DIC with poor prognosis. The resulting factor XIIa release can be used as an independent potential prognostic marker for DIC. Activation of factor XII-mediated coagulation may be a potential therapeutic target in DIC,

Increase of glycosaminoglycans and metalloproteinases 2 and 9 in liver extracellular matrix on early stages of extrahepatic cholestasis

CONTEXT

Cholestasis produces hepatocellular injury, leukocyte infiltration, ductular cells proliferation and fibrosis of liver parenchyma by extracellular matrix replacement.

OBJECTIVE

Analyze bile duct ligation effect upon glycosaminoglycans content and matrix metalloproteinase (MMPs) activities.

METHODS

Animals (6-8 weeks; n = 40) were euthanized 2, 7 or 14 days after bile duct ligation or Sham-surgery. Disease evolution was analyzed by body and liver weight, seric direct bilirubin, globulins, gamma glutamyl transpeptidase (GGT), alkaline phosphatase (Alk-P), alanine and aspartate aminotransferases (ALT and AST), tissue myeloperoxidase and MMP-9, pro MMP-2 and MMP-2 activities, histopathology and glycosaminoglycans content.

RESULTS

Cholestasis caused cellular damage with elevation of globulins, GGT, Alk-P, ALT, AST. There was neutrophil infiltration observed by the increasing of myeloperoxidase activity on 7 (P = 0.0064) and 14 (P = 0.0002) groups which leads to the magnification of tissue injuries. Bile duct ligation increased pro-MMP-2 (P = 0.0667), MMP-2 (P = 0.0003) and MMP-9 (P<0.0001) activities on 14 days indicating matrix remodeling and establishment of inflammatory process. Bile duct ligation animals showed an increasing on dermatan sulfate and/or heparan sulfate content reflecting extracellular matrix production and growing mitosis due to parenchyma depletion.

CONCLUSIONS

Cholestasis led to many changes on rats' liver parenchyma, as so as on its extracellular matrix, with major alterations on MMPs activities and glycosaminoglycans content.

Differential bradykinin B1 and B2 receptor regulation in cell death induced by hepatic ischaemia/reperfusion injury

In the present study, we have demonstrated that the kinin B1 receptor may participate in apoptotic cell death signalling, whereas the B2 receptor may be involved in necrotic cell death during IRI.

The ultrasound frequency determines the degree of intrinsic coagulation activation

Diagnostic ultrasound activates intrinsic coagulation. The aim of the present work was to quantify the action of different ultrasound frequencies on the contact phase of human blood coagulation. Pooled normal citrated platelet-poor plasma in 2 ml aliquots in polypropylene monovettes was exposed to diagnostic ultrasound, changing the ultrasound frequency from 17 to 15 to 12 to 8 to 7 MHz (at an intensity of 1.1 MI). After 0-2 min (23°C), 400 μl samples were withdrawn and placed into polypropylene Eppendorf cups. Forty microliters of plasma sample was pipetted into U-wells polystyrene microtiter plates of high purity (Brand781600). Immediately thereafter, the recalcified coagulation activity assay (RECA) was performed. Seventeen megahertz ultrasound exposure was the weakest activator of intrinsic coagulation of all frequencies tested: even 2 min of exposure at 23°C enhanced F2a generation by only about three-fold. The shorter the ultrasound exposure, the better the action against intrinsic hemostasis: 0.5 min of ultrasound exposure at 23°C induced less than two-fold thrombin generation in all frequencies tested. One minute ultrasound exposure (23°C) triggered intrinsic coagulation strongest at 8 MHz, showing an approximately four-fold increase in F2a generation. A 1.5 min of ultrasound exposure (23°C) triggered coagulation strongest at 7 MHz, showing an approximately 14-fold increase in F2a generation. Two minute of ultrasound exposure (23°C) triggered coagulation strongest at 15 MHz, showing an approximately 18-fold increase in F2a generation. Ultrasound has to be considered as a potential inducer of pathologic systemic coagulation. Patients at risk for increased coagulation activation and/or liver insufficiency should be protected with low molecular weight heparin, if a prolonged ultrasound diagnostic is planned. Ultrasound frequencies of about 17 MHz are the weakest activators of intrinsic coagulation. Ultrasound frequencies of about 7 MHz might be used for therapeutic induction of coagulation activation, such as in patients with severe cerebral or hepatic hemorrhages.