Kinin-B1 receptors in ischaemia-induced pancreatitis: Functional importance and cellular localisation

In this study we compare the role of kininB1 and B2 receptors during ischaemia/reperfusion of rat pancreas. Our investigations were prompted by the observation that infusion of a kininB2 receptor antagonist produced significant improvement in acute experimental pancreatitis. In an acute model with two hours of ischaemia/two hours of reperfusion, application of the kininB1 receptor antagonist (CP-0298) alone, or in combination with kininB2 receptor antagonist (CP-0597), significantly reduced the number of adherent leukocytes in postcapillary venules. In a chronic model with five days of reperfusion, the continuous application of kininB1 receptor antagonist or a combination of kininB1 and B2 receptor antagonists markedly reduced the survival rate. In kininreceptor binding studies kininB1 receptor showed a 22-fold increase in expression during the time of ischaemia/ reperfusion. Carboxypeptidase M activity was upregulated 10-fold following two hours of ischaemia and two hours of reperfusion, provided the appropriate specific ligand, desArg10-kallidin and/or desArg9-bradykinin, was used. The occurrence of kininB1 receptor binding sites on acinar cell membranes was demonstrated by microautoradiography. With a specific antibody, the localisation of kininB1 receptor protein was confirmed at the same sites. In conclusion, we have demonstrated the upregulation of the pancreatic acinar cell kininB1 receptors during ischaemia/reperfusion. The novel functional finding was that antagonism of the kininB1 receptors decreased the survival rate in an experimental model of pancreatitis

Inhibitor regulation of tissue kallikrein activity in the synovial fluid of patients with rheumatoid athritis

Tissue kallikrein (TK) and 1-antitrypsin (AT)/TK complexes can be detected in SF from patients with RA if components of the fluids which interfere with the detection of TK are removed. 2-Macroglobulin (2-M) in SF was demonstrated to contain trapped proteases which were still active in amidase assays. Removal of 2-M from RA SF reduced their amidase activity. However, at least some of the remaining activity was due to TK because it was soya bean trypsin inhibitor resistant and trasylol sensitive and was partly removed by affinity chromatography on anti-TK sepharose. Removal of RF from the fluids reduced the values obtained for TK levels by ELISA. Addition of SF to human urinary kallikrein (HUK) considerably reduced the levels of TK detected suggesting the presence of a TK ELISA inhibitor in the fluids. Removal of components of >300 kDa from SF markedly reduced the TK ELISA inhibitory activity and increased the values for both the TK and l-AT/TK levels in fluids as measured by ELISA. It is considered this novel inhibitor does not bind to the active site of TK but rather binds to the site reactive with anti-TK antibodies

Visualisation of tissue kallikrein, kininogen and kinin receptors in human skin following trauma and in dermal diseases

During dermal injury and inflammation the serine proteases kallikreins cleave endogenous, multifunctional substrates (kininogens) to form bradykinin and kallidin. The actions of kinins are mediated by preferential binding to constitutively expressed kinin-B2 receptors or inducible kinin-B1 receptors. A feature of the kinin-B1 receptors is that they show low levels of expression, but are distinctly upregulated following tissue injury and inflammation. Because recent evidence suggested that kinin-B1 receptors may perform a protective role during inflammation, we investigated the specific occurrence of the kallikrein-kinin components in skin biopsies obtained from normal skin, patients undergoing surgery, basalioma, lichenificated atopic eczema, and psoriasis. The tissue was immunolabelled in order to determine the localisation of tissue pro-kallikrein, kallikrein, kininogen and kinin receptors. The kinin components were visualised in normal, diseased and traumatised skin, except that no labelling was observed for kininogen in normal skin. Of the five types of tissue examined, upregulation of kinin-B1 receptors was observed only in skin biopsies obtained following surgery. In essence, the expression of kinin-B1 receptors did not appear to be enhanced in the other biopsies. Within the multiple steps of the inflammatory cascade in wound healing, our results suggest an important regulatory role for kinin-B1 receptors during the first phase of inflammation following injury

The association of antiphospholipid antibodies with severe early-onset pre-eclampsia

Objective. To confirm the association of antiphospholipid antibodies with early onset of severe pre-eclampsia before 30 weeks' gestation.Study design. Thirty-four patients with diastolic blood pressure levels ≥ 110 mmHg and at least 2+ proteinuria before the 30th week of pregnancy were randomly chosen for inclusion in the study. Blood samples were taken for assessment of anticardiolipin antibodies (ACAs), lupus anticoagulant, syphilitic serology and antinuclear antibodies. Fifteen normal antenatal patients matched for age, parity and gestational age acted as control subjects.Results. Four of the 34 women (11,7%) in the study group had elevated levels of both ACAs and lupus anticoagulant, compared with none in the control group. This was not found to be statistically different.Conclusion. Given the low incidence of positive ACAs in early-onset severe pre-eclampsia it is unlikely that they are implicated in its pathogenesis. It is possible that they represent a small subset of patients with alternative or combined pathology

Role of human tissue kallikrein in gastrointestinal stromal tumour invasion

Background: Human tissue kallikrein (hK1) generates vasodilator kinins from kininogen and promotes angiogenesis by kinin-dependent and kinin-independent mechanisms. Here, we investigate the expression and functional relevance of hK1 in human gastrointestinal stromal tumour (GIST).<p></p> Methods: Vascularisation and hK1 expression of GIST samples were assessed by immunohistochemistry. In two GIST cell lines, hK1 expression was assessed by PCR, and hK1 protein levels and activity were measured by ELISA and an amidolytic assay, respectively. The effect of hK1 silencing, inhibition or overexpression on GIST cell proliferation, migration and paracrine induction of angiogenesis was studied. Finally, local and systemic levels of hK1 were assessed in mice injected with GIST cells.<p></p> Results: Human tissue kallikrein was detected in 19 out of 22 human GIST samples. Moreover, GIST cells express and secrete active hK1. Titration of hK1 demonstrated its involvement in GIST invasive behaviour, but not proliferation. Furthermore, hK1 released by GIST cells promoted endothelial cell migration and network formation through kinin-dependent mechanisms. Gastrointestinal stromal tumour implantation in nude mice resulted in local and systemic hK1 expression proportional to tumour dimension.<p></p> Conclusions: Human tissue kallikrein is produced and released by GIST and participates in tumour invasion. Further studies are needed to validate hK1 as a diagnostic biomarker and therapeutic target in GIST