The relationship between clinical phenotype and kallikrein-kinin bioregulation in different forms of arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) have shown increased levels of neutrophils generating kallikrein-kinin peptides in blood which are potent mediators of inflammation. This study investigated the association between the bioregulation of kinin-mediated inflammation with the clinical, quality of life, and imaging characteristics (e.g. ultrasonography) of different arthritides.

METHODS

Patients with osteoarthritis (OA, n = 29), gout (n = 10) and RA (n = 8) were recruited and screened for clinical symptoms, quality of life, and ultrasonographical assessment of arthritis. Blood neutrophils were assessed for the expression of bradykinin receptors (B1R and B2R), kininogens and kallikreins by immunocytochemistry with visualization by bright field microscopy. Levels of plasma biomarkers were measured by ELISA and cytometric bead array.

RESULTS

Quality of life (SF-36 domains and summary scores; including pain; and, HAQ) was similar across OA, gout and RA patients; with the exception of worse physical functioning scores between OA and gout patients. Synovial hypertrophy (on ultrasound) differed between groups (p = 0.001), and the dichotomised Power Doppler (PD) score of greater than or equal to 2 (PD-GE2) was marginally significant (p = 0.09). Plasma IL-8 were highest in patients with gout followed by RA and OA (both, P < 0.05). Patients with RA had higher plasma levels of sTNFR1, IL-1β, IL-12p70, TNF and IL-6, compared to OA and gout patients (all, P < 0.05). Patients with OA had higher expression of K1B and KLK1 on blood neutrophils followed by RA and gout patients (both, P < 0.05). Bodily pain correlated with B1R expression on blood neutrophils (r = 0.334, p = 0.05), and inversely with plasma levels of CRP (r = -0.55), sTNFR1 (r = -0.352) and IL-6 (r = -0.422), all P < 0.05. Expression of B1R on blood neutrophils also correlated with Knee PD (r = 0.403) and PD-GE2 (r = 0.480), both P < 0.05.

CONCLUSIONS

Pain levels and quality of life were similar between patients with OA, RA and gout with knee arthritis. Plasma inflammatory biomarkers and B1R expression on blood neutrophils correlated with pain. Targeting B1R to modulate the kinin-kallikrein system may pose as a new therapeutic target in the treatment of arthritis.

Kinin B1 Receptor Signaling in Skin Homeostasis and Wound Healing

Kinins are proinflammatory peptides that are formed in the skin by the enzymatic action of tissue kallikrein (KLK1) on kininogens. Tissue kallikrein is produced by eccrine sweat glands and also by cells of the stratum granulosum and other skin appendages. Kinin formation may be favored during inflammatory skin disorders when plasma constituents, including kininogens, extravasate from venules and capillaries, which have increased permeability in response to the plethora of inflammatory mediators generated in the course of acute inflammation. By activating either kinin B1 or B2 receptors, kinins modulate keratinocyte differentiation, which relays on activation of several signaling systems that follows receptor stimulation. Participation of the kinin B1 receptor in wound healing is still a matter of controversy though some studies indicate that B1 receptor stimulation regulates keratinocyte migration by controlling metalloproteases 2 and 9 production and by improving wound closure in a mouse model. Development of more stable kinin B1 receptor agonists may be beneficial to modulate wound healing, especially if we take into account that the B1 receptor is up-regulated by inflammation and by cytokines generated in the inflamed microenvironment.

Overview of tissue kallikrein and kallikrein-related peptidases in breast cancer

The kallikrein family comprises tissue kallikrein and 14 kallikrein-related peptidases (KLKs) recognized as a subgroup of secreted trypsin- or chymotrypsin-like serine proteases. KLKs are expressed in many cellular types where they regulate important physiological activities such as semen liquefaction, immune response, neural development, blood pressure, skin desquamation and tooth enamel formation. Tissue kallikrein, the oldest member and kinin-releasing enzyme, and KLK3/PSA, a tumor biomarker for prostate cancer are the most prominent components of the family. Additionally, other KLKs have shown an abnormal expression in neoplasia, particularly in breast cancer. Thus, increased levels of some KLKs may increase extracellular matrix degradation, invasion and metastasis; other KLKs modulate cell growth, survival and angiogenesis. On the contrary, KLKs can also inhibit angiogenesis and produce tumor suppression. However, there is a lack of knowledge on how KLKs are regulated in tumor microenvironment by molecules present at the site, namely cytokines, inflammatory mediators and growth factors. Little is known about the signaling pathways that control expression/secretion of KLKs in breast cancer, and further how activation of PAR receptors may contribute to functional activity in neoplasia. A better understanding of these molecular events will allow us to consider KLKs as relevant therapeutic targets for breast cancer.

Functional interrelationships between the kallikrein-related peptidases family and the classical kinin system in the human neutrophil

In the human neutrophil, kallikrein-related peptidases (KLKs) have a significant functional relationship with the classical kinin system as a kinin B1 receptor agonist induces secretion of KLK1, KLK6, KLK10, KLK13 and KLK14 into the medium. Secretion of KLK1, the kinin-forming enzyme, may perpetuate formation of kinin in the inflammatory milieu by hydrolyzing extravasated kininogens present in tissue edema. Secretion of KLKs into the inflammatory milieu, induced by kinins or other proinflammatory mediators, provides the human neutrophil with a wide range of molecular interactions to hydrolyze different cellular and extracellular matrix components, which may be of critical relevance in different mechanisms involving inflammation.

GPER-1/GPR30 a novel estrogen receptor sited in the cell membrane: therapeutic coupling to breast cancer

INTRODUCTION

Breast cancer is clinically classified as 'estrogen-positive' when at least 1% of cancer cells stain for the estrogen receptor alpha (ERα). However, recent research on both basic and clinical aspects of breast cancer suggests that GPER-1 (G protein-coupled estrogen receptor-1) may have an important role in breast cancer. Areas covered: This review provides a comprehensive and systematic literature search on GPER-1. We have focused on the role of GPER-1 in breast cancer and on resistance to endocrine therapy, an unsolved clinical issue still under discussion. Expert opinion: The discovery of GPER-1 as a novel estrogen receptor is unique and the signaling pathways activated by its stimulation, when compared to the classical nuclear ERα, indicate a potential role of GPER-1 in the genesis and mechanisms of drug resistance in breast cancer. Tumors expressing ERα represent the largest group of breast cancer patients indicating that more women eventually die from ERα-positive breast tumors than from other more malignant breast cancer subtypes such as HER2-positive and the triple negative groups. It is important to develop new strategies on endocrine therapy with regard to ERα and GPER-1 receptors to achieve innovative successful therapeutic tools.

Activation of the human keratinocyte B1 bradykinin receptor induces expression and secretion of metalloproteases 2 and 9 by transactivation of epidermal growth factor receptor

The B1 bradykinin receptor (BDKRB1) is a component of the kinin cascade localized in the human skin. Some of the effects produced by stimulation of BDKRB1 depend on transactivation of epidermal growth factor receptor (EGFR), but the mechanisms involved in this process have not been clarified yet. The primary purpose of this study was to determine the effect of a BDKRB1 agonist on wound healing in a mouse model and the migration and secretion of metalloproteases 2 and 9 from human HaCaT keratinocytes and delineate the signalling pathways that triggered their secretion. Although stimulation of BDKRB1 induces weak chemotactic migration of keratinocytes and wound closure in an in vitro scratch-wound assay, the BDKRB1 agonist improved wound closure in a mouse model. BDKRB1 stimulation triggers synthesis and secretion of both metalloproteases, effects that depend on the activity of EGFR and subsequent phosphorylation of ERK1/2 and p38 mitogen-activated protein kinases and PI3K/Akt. In the mouse model, immunoreactivity for both gelatinases was concentrated around wound borders. EGFR transactivation by BDKRB1 agonist involves Src kinases family and ADAM17. In addition to extracellular matrix degradation, metalloproteases 2 and 9 regulate cell migration and differentiation, cell functions that are associated with the role of BDKRB1 in keratinocyte differentiation. Considering that BDKRB1 is up-regulated by inflammation and/or by cytokines that are abundant in the inflammatory milieu, more stable BDKRB1 agonists may be of therapeutic value to modulate wound healing.

Expression and bioregulation of the kallikrein-related peptidases family in the human neutrophil

The family of kallikrein-related peptidases (KLKs) has been identified in a variety of immunolabeled human tissue sections, but no previous study has experimentally confirmed their presence in the human neutrophil. We have investigated the expression and bioregulation of particular KLKs in the human neutrophil and, in addition, examined whether stimulation by a kinin B1receptor (B1R) agonist or fMet-Leu-Phe (fMLP) induces their secretion. Western blot analysis of neutrophil homogenates indicated that the MM of the KLKs ranged from 27 to 50 kDa. RT-PCR showed that blood neutrophils expressed only KLK1, KLK4, KLK10, KLK13, KLK14 and KLK15 mRNAs, whereas the non-differentiated HL-60 cells expressed most of them, with exception of KLK3 and KLK7. Nevertheless, mRNAs for KLK2, KLK5, KLK6 and KLK9 that were previously undetectable appeared after challenging with a mixture of cytokines. Both kinin B1R agonist and fMLP induced secretion of KLK1, KLK6, KLK10, KLK13 and KLK14 into the culture medium in similar amounts, whereas the B1R agonist caused the release of lower amounts of KLK2, KLK4 and KLK5. When secreted, the differing proteolytic activity of KLKs provides the human neutrophil with a multifunctional enzymatic capacity supporting a new dimension for its role in human disorders of diverse etiology.

Bioregulation of kallikrein-related peptidases 6, 10 and 11 by the kinin B₁ receptor in breast cancer cells

The sera of patients with breast cancer have higher levels of des[Arg(9)]bradykinin, a kinin B1 receptor (B1R) agonist, than that from healthy individuals. Stimulation of breast cancer cells with the analog Lys-des[Arg(9)]bradykinin causes release of metalloproteinases-2 and -9 and increases cell proliferation. We examined the possibility that breast cancer cells, in addition to B1R, express the kinin-forming protease true tissue kallikrein (KLK1) and the endogenous proteins termed kininogens from which kinins are enzymatically released. Furthermore, we investigated whether stimulation of breast cancer cells with a B1R agonist would modify the cellular levels of KLK6, KLK10 and KLK11, three kallikrein-related peptidases with a still poorly-understood biological role in breast cancer. We found that breast cancer cells expressed KLK1 and kininogens, and that stimulation of estrogen-sensitive breast cancer cells with the B1R agonist produced down-regulation of KLK10 (a protease associated with growth suppression) but up-regulation of KLK11 and KLK6 (peptidases related to increased cell proliferation and invasiveness, respectively). Furthermore, we showed that the B1R agonist acts as a functional stimulus for the secretion of KLK1 and KLK6, an event relevant for kinin production and cell invasion, respectively.

Kinin B1 receptor regulates interactions between neutrophils and endothelial cells by modulating the levels of Mac-1, LFA-1 and intercellular adhesion molecule-1

Kinins are pro-inflammatory peptides that mimic the cardinal features of inflammation. We examined the concept that expression levels of endothelial intercellular adhesion molecule-1 (ICAM-1) and neutrophil integrins Mac-1 and LFA-1 are modulated by the kinin B1 receptor (B1R) agonist, Lys-des[Arg(9)]bradykinin (LDBK). Stimulation of endothelial cells with LDBK increased the levels of ICAM-1 mRNA transcripts/protein, and also of E-selectin and platelet endothelial adhesion molecule-1. ICAM-1 levels increased in a magnitude comparable with that produced by TNF-α. This stimulatory effect was reduced when endothelial cells, which had been previously transfected with a B1R small interfering RNA, were stimulated with LDBK, under comparable conditions. Similarly, LDBK produced a significant increase in protein levels of LFA-1 and Mac-1 integrins in human neutrophils, an effect that was reversed by pretreatment of cells with 10 µg/ml cycloheximide or a B1R antagonist. Functional experiments performed with post-confluent monolayers of endothelial cells stimulated with LDBK and neutrophils primed with TNF-α, and vice versa, resulted in enhanced adhesiveness between both cells. Neutralizing Abs to ICAM-1 and Mac-1 reduced the adhesion between them. Our results indicate that kinin B1R is a novel modulator that promotes adhesion of leukocytes to endothelial cells, critically enhancing the movement of neutrophils from the circulation to sites of inflammation.

Expression of HER2 and bradykinin B1 receptors in precursor lesions of gallbladder carcinoma

AIM: To determine the expression of HER2 and bradykinin B₁ receptors (B₁R) in the two pathogenic models of gallbladder cancer: the metaplasia-dysplasia-carcinoma and the adenoma-carcinoma pathways.

METHODS: Receptor proteins were visualized by immunohistochemistry on 5-μm sections of paraffin-embedded tissue. Expression of both receptors was studied in biopsy samples from 92 patients (6 males and 86 females; age ranging from 28 to 86 years, mean 56 years). High HER2 expression in specimens was additionally investigated by fluorescence in situ hybridization. Cell proliferation in each sample was assessed by using the Ki-67 proliferation marker.

RESULTS: HER2 receptor protein was absent in adenomas and in normal gallbladder epithelium. On the contrary, there was intense staining for HER2 on the basolateral membrane of epithelial cells of intestinal metaplasia (22/24; 91.7%) and carcinoma in situ (9/10; 90%), the lesions that displayed a significantly high proliferation index. Protein up-regulation of HER2 in the epithelium with metaplasia or carcinoma in situ was not accompanied by HER2 gene amplification. A similar result was observed in invasive carcinomas (0/12). The B₁R distribution pattern mirrored that of HER2 except that B₁R was additionally observed in the adenomas. The B₁R appeared either as cytoplasmic dots or labeling on the apical cell membrane of the cells composing the epithelia with intestinal metaplasia (24/24; 100%) and carcinoma in situ (10/10; 100%) and in the epithelial cells of adenomas. In contrast, both HER2 (4/12; 33%) and B₁R (1/12; 8.3%) showed a low expression in invasive gallbladder carcinomas.

CONCLUSION: The up-regulation of HER2 and B₁R in precursor lesions of gallbladder carcinoma suggests cross-talk between these two receptors that may be of importance in the modulation of cell proliferation in gallbladder carcinogenesis.

Effects of the demethylating agent, 5-azacytidine, on expression of the kallikrein-kinin genes in carcinoma cells of the lung and pleura

Tissue kallikrein (KLK1) and plasma kallikrein (KLKB1) may regulate the growth and proliferation of tumours of the lung and pleura, through the generation of kinin peptides that signal through the kinin B(1) (BDKRB1) and B(2) (BDKRB2) receptors. The development and progression of cancer results from genetic mutations, as well as epigenetic changes that include methylation of DNA at CpG islands. The aim of this study was to assess whether expression of the kallikrein-kinin genes in lung cancer and mesothelioma cells is regulated by DNA methylation. Quantitative reverse transcriptase-PCR and immunocytochemistry showed differences in the basal expression of the kallikrein-kinin genes and proteins in lung carcinoma and mesothelioma cells, compared with non-malignant lung epithelial and mesothelial cells, respectively. Following treatment with the demethylating agent, 5-azacytidine (5-AZA), KLKB1 mRNA expression was consistently increased in both lung carcinoma and mesothelioma cells, whereas KLK1, BDKRB1 and BDKRB2 mRNA expression was decreased or unchanged. Increased expression of KLKB1 after 5-AZA treatment suggests it may function as a tumour suppressor gene in cancers of the lung and pleura. Studies on DNA methylation of the kallikrein-kinin genes will enhance understanding of their role in carcinogenesis and provide insights into the importance of kallikreins as tumour biomarkers.

Kinin B1 receptor activation turns on exocytosis of matrix metalloprotease-9 and myeloperoxidase in human neutrophils: involvement of mitogen-activated protein kinase family

During neutrophil activation and degranulation, MMP-9 and MPO are released into the extracellular space to propagate inflammatory disorders. As kinin peptides are major participants in acute inflammatory responses, and the G-protein-coupled B(1)R mediates the chemotaxis of human neutrophils, we examined the release of the neutrophil enzymes MMP-9 and MPO by the B(1)R agonist LDBK and determined the signaling pathways that may regulate this cellular effect. Cytochalasin-treated and -untreated neutrophils were suspended in HBSS and stimulated with a range concentration of LDBK for 5 min. Zymography and Western blotting revealed that LDBK induced the release of MMP-9 and MPO. The use of specific signaling transduction inhibitors showed that release of MMP-9 depended on ERK1/2 and p38 MAPKs, whereas release of MPO involved only the p38 cascade. Inhibition of the key steps in these pathways showed that the release of both enzymes depended on PKC and PI3K. Stimulation of neutrophils with LDBK produced phosphorylation of ERK1/2 and p38 MAPK, which was inhibited by B(1)R antagonists. The phosphorylated ERK1/2 MAPK translocated to the neutrophil nucleus, suggesting that transcription of new genes may follow activation of B(1)R. Our results demonstrate that in human neutrophils, activation of kinin B(1)R by LDBK initiates separate signaling cascades that trigger the release of MMP-9 and MPO from tertiary and primary granules, respectively, suggesting that the B(1)R plays a pivotal role in inflammatory disorders.

Kallikreins, kininogens and kinin receptors on circulating and synovial fluid neutrophils: role in kinin generation in rheumatoid arthritis

OBJECTIVES

Neutrophils traffic into and have the capacity to generate kinins in SF of RA patients. The aim of this study was to assess the expression of kallikreins, kininogens and kinin receptors in circulating and SF neutrophils, as well as synovial tissue of RA patients, and to assess kinin generation in SF.

METHODS

Neutrophils were isolated from blood and SF of RA patients and blood of healthy volunteers. Expression of kallikreins, kininogens and kinin receptors in neutrophils and synovial tissue was assessed by immunocytochemistry using specific antibodies, with visualization by brightfield and confocal microscopy. Levels of basal and generated kinins in SF of RA patients were measured by ELISA.

RESULTS

Kinin labelling was significantly reduced, indicating the loss of the kinin moiety from kininogen on circulating (P < 0.001) and SF neutrophils (P < 0.05) of RA patients. Immunolabelling of tissue kallikrein was also decreased, whereas kinin B(1) and B(2) receptor expression was increased in circulating and SF neutrophils of RA patients. Immunolabelling of kallikreins and kinin receptor proteins was similar in RA and normal synovial tissues. The basal kinin level in SF of RA patients was 5.7 +/- 6.1 ng/ml and the mean concentration of kinins generated in vitro was 80.6 +/- 56.3 ng/ml. The capacity for kinin generation was positively correlated with measures of disease activity.

CONCLUSIONS

Kallikrein-kinin proteins on neutrophils play an important role in kinin generation and the pathophysiology of RA. Specific kallikrein and kinin receptor antagonists may be useful as IA therapies for inflamed joints.

Epigenetic regulation of human epithelial cell cancers

Cancer is the second leading cause of death in industrialized countries, with epithelial cell cancers (carcinomas) representing approximately 85% of all diagnosed cancers. The 5-year survival rate for many carcinomas remains low, highlighting the requirement for improved diagnosis and more effective therapies. Epigenetic modifications that do not involve changes in the DNA sequence, but result in changes in gene expression, are rapidly being realized as important in carcinogenesis. Evidence is emerging that DNA methylation, histone modification and alternative mRNA splicing are involved in various human epithelial cell cancers, and diagnostic and therapeutic strategies based on these epigenetic phenomena are under investigation. This review provides an overview of studies demonstrating the importance of epigenetic regulation of gene expression in the diagnosis, progression and response to treatment of human carcinomas. The use of therapeutic agents to reverse these epigenetic changes, either as single treatments or in combination with other therapies, is also discussed.

Expression of tissue and plasma kallikreins and kinin B1 and B2 receptors in lung cancer

Tissue kallikrein (hK1) and plasma kallikrein (PK, hKB1) are serine proteases that produce biologically active kinin peptides from endogenous kininogen substrates. There is evidence linking the kallikreins and the mitogenic kinin peptides to carcinogenesis. The aim of this study was to investigate the expression of tissue prokallikrein (pro-hK1), plasma prekallikrein (PPK, pre-hKB1) and kinin B1 and B2 receptor proteins in different subtypes of lung cancer. Immunohistochemistry, using specific antibodies, was performed on archived normal lung sections and sections from adenocarcinomas, squamous cell carcinomas, large cell carcinomas, small cell carcinomas and carcinoid tumours of the lung. Immunoperoxidase labelling was visualised by brightfield microscopy and immunofluorescence labelling by confocal microscopy. Extensive cytoplasmic expression of pro-hK1 and PPK was observed, which was similar in small cell and non-small cell tumours. However, nuclear labelling for the kallikreins was absent or limited. The kinin B1 and B2 receptors were highly expressed in the cytoplasm of all tumour types and in the nuclei of non-small cell tumours. Further studies are required to assess the functional significance of the expression of hK1, PK and kinin receptors in lung tumours, and whether any of these proteins may be potential biomarkers for specific subtypes of lung carcinoma.

Novel expression of kallikreins, kallikrein-related peptidases and kinin receptors in human pleural mesothelioma

Malignant mesothelioma is an aggressive cancer of the pleura that is causally related to exposure to asbestos fibres. The kallikrein serine proteases [tissue (hK1) and plasma (hKB1) kallikreins, and kallikrein-related peptidases (KRP/hK2-15)] and the mitogenic kinin peptides may have a role in tumourigenesis. However, it is not known whether hK1, hKB1, KRP/hK proteins or kinin receptors are expressed in pleural mesotheliomas. The expression of hK1, hKB1, KRP/hK2, 5, 6, 7, 8 and 9, and kinin B(1) and B(2) receptors was assessed in archived selected normal tissue and mesothelioma tumour sections by immunoperoxidase and immunofluorescence labelling. hK1, hKB1 and kinin B(1) and B(2) receptors were expressed in malignant cells of the epithelioid and sarcomatoid components of biphasic mesothelioma tumour cells. The percentage of cells with cytoplasmic and nuclear labelling and the intensity of labelling were similar for hK1, hKB1 and the kinin receptors. KRP/hK2, 6, 8 and 9 were also expressed in the cytoplasm and nuclei of mesothelioma cells, whereas KRP/hK5 and hK7 showed predominantly cytoplasmic localisation. This is a first report, but further studies are required to determine whether these proteins have a functional role in the pathogenesis of mesothelioma and/or may be potential biomarkers for pleural mesothelioma.

Comparison of kinin B(1) and B(2) receptor expression in neutrophils of asthmatic and non-asthmatic subjects

Kinins have been implicated in the pathophysiology of asthma and activation of kinin receptors stimulates neutrophil chemotaxis. However, the expression of kinin receptors on neutrophils of asthmatic subjects has not been assessed. The aim of this study was to compare the expression of kinin B(1) and B(2) receptor mRNA and proteins in neutrophils of asthmatic and non-asthmatic subjects, and to assess whether inhaled corticosteroid treatment may influence expression of the kinin receptors. Neutrophils were isolated from peripheral blood of asthmatic (n=27) and non-asthmatic subjects (n=14). The presence of kinin B(1) and B(2) receptor protein on neutrophils was confirmed by immunolabeling with specific antibodies followed by immunoperoxidase, immunofluorescence and FACS detection. Kinin B(1) and B(2) receptor mRNA expression was assessed by RT-PCR. Quantitative image analysis of fluorescence immunolabeled neutrophils showed no differences in kinin B(1) or B(2) receptor protein expression between asthmatic and non-asthmatic subjects. Similarly, quantitative real time RT-PCR analysis demonstrated no differences in expression of mRNA for the kinin B(1) or B(2) receptors between asthmatic and non-asthmatic subjects. However, B(1) receptor mRNA expression was significantly lower in asthmatic subjects using > or =2000 microg of inhaled corticosteroid per day (p<0.05) and B(1) receptor protein levels also tended to be lower in these subjects. Corticosteroids may have a beneficial anti-inflammatory effect in asthma by down-regulating B(1) receptor expression on neutrophils, thereby decreasing the migration of these inflammatory cells into the airways.

Physiological concentrations of transforming growth factor beta1 selectively inhibit human dendritic cell function

In this study the effects of different in vitro conditioning with transforming growth factor (TGF) beta1 on human monocyte-derived DC maturation (hMo-DC) were investigated. hMo-DC differentiated in the presence of physiologically relevant concentrations of TGFbeta1 (2 ng/ml) failed to undergo complete maturation despite adequate stimulation with LPS or LPS+IFNgamma. These hMo-DC did not produce IL-12p70 or PGE2, and showed decreased IL-10 and IL-18 production and HLA-DR expression. However, the expression of these molecules, except for IL-12p70, was not significantly affected in hMo-DC differentiated in the presence of lower concentrations of TGFbeta1 (0.2 and 0.02 ng/ml). Exposure of hMo-DC to TGFbeta1 (2 ng/ml) after they had completed differentiation had minimal effects. Thus, the functional response of hMo-DC to LPS or LPS+IFNgamma depended on the stage of hMo-DC differentiation at which cells were first exposed to TGFbeta1 and on the concentration of TGFbeta1. These results suggest that in the in vivo micro-environment, the concentrations and the timing of monocyte exposure to TGFbeta1 may be crucial in the differentiation of DC toward more or less mature phenotypes, and this may have important implications for DC functions. The decrease in T-cell proliferation and a small increase in IL-5 production by T cells co-cultured with hMo-DC that had been treated with TGFbeta1, suggest the possibility that in vivo such DC may provide chronic, but incomplete signals to T cells, and this could be a potential mechanism underlying polarisation of T cells towards anergy.

Current status of tissue kallikrein inhibitors: importance in cancer

The past decade has seen an increase in the understanding of the structure and function of protease inhibitors. The molecular basis of the interaction between a variety of biological substrates or synthetic inhibitors and serine proteases of the kallikrein family has provided insights into inhibitor protein-protease reactive site interactions, which have proved of value in the design of new kallikrein inhibitors. This review focuses on the current understanding of the functional status of kallikrein inhibitors, which include a variety of molecules derived from plant, reptile and mammalian sources, as well as synthetic agents.

Expression of kinin B1 and B2 receptors in immature, monocyte-derived dendritic cells and bradykinin-mediated increase in intracellular Ca2+ and cell migration

The kinins, bradykinin (BK) and Lys-des[Arg(9)]-BK, are important inflammatory mediators that act via two specific G protein-coupled kinins, B(1) and B(2) receptors (B(2)R). Kinins influence the activity of immune cells by stimulating the synthesis of cytokines, eicosanoids, and chemotactic factors. Whether human dendritic cells (DC) express kinin receptors and whether kinins influence DC function are unknown. Fluorescence immunocytochemistry and RT-PCR were used to demonstrate that immature human monocyte-derived DC (hMo-DC) constitutively expressed kinins B(1)R and B(2)R. Kinin receptor expression was induced on the 3rd and 4th days of culture during differentiation of hMo-DC from monocytes and was not dependent on the presence of IL-4 or GM-CSF. Although monocytes also expressed B(2)R mRNA, the protein was not detected. The kinin agonists BK and Lys-des[Arg(9)]-BK up-regulated the expression of their respective receptors. BK, acting via the B(2)R, increased intracellular Ca(2+), as visualized by confocal microscopy using the fluorescent Ca(2+) dye, Fluor-4 AM. Evaluation of migration in Trans-well chambers demonstrated significant enhancement by BK of migration of immature hMo-DC, which was B(2)R-dependent. However, kinins did not induce maturation of hMo-DC. The novel finding that kinin receptors are constitutively expressed in immature hMo-DC suggests that these receptors may be expressed in the absence of proinflammatory stimuli. BK, which increases the migration of immature hMo-DC in vitro, may play an important role in the migration of immature DC in noninflammatory conditions and may also be involved in the recruitment of immature DC to sites of inflammation.

Cellular expression of plasma prekallikrein in human tissues

Plasma prekallikrein (PPK) is synthesised in hepatocytes and secreted into the blood, where it participates in the surface-dependent activation of blood coagulation, fibrinolysis, kinin generation and inflammation. Recently we demonstrated by quantitative RT-PCR that the human PPK gene is transcribed not only in the liver, but also in various non-hepatic human tissues at significant levels. However, up to now no reliable information is available concerning protein synthesis in the corresponding human tissues. Here we demonstrate by immunohistochemical studies that PPK or plasma kallikrein (PK) is localised in cells of different embryologically derived human tissues. In the human nephron, single cells of the distal tubules stained intensely, while the cytoplasm of cells forming proximal tubules and collecting ducts stained uniformly. PPK/PK was localised in hepatic epithelial cells of the liver, in cells of the pancreatic islet of Langerhans, in the interstitial Leydig cells of the testes, in the follicular and thecal granulosa cells of the ovary, and in the parotid gland, oesophagus, skin, respiratory tract, prostate and breast. We conclude that the cellular localisation of PPK/PK in multiple different progenitor-derived cells indicates specific cellular functions of this enzyme, in addition to its known function in the blood.

Activation of kinin B1 receptors induces chemotaxis of human neutrophils

Kinins are biologically active peptides that are powerful mediators of cellular inflammation. They mimic the cardinal signs of inflammation by inducing vasodilatation and by increasing vascular permeability and pain. Neutrophils are chemoattracted to sites of inflammation by several stimuli. However, the evidence concerning the chemotactic effect of kinin peptides has been contradictory. We analyzed the chemotactic effect of kinin B(1) receptor agonists on neutrophils isolated from peripheral blood of human healthy subjects. Chemotaxis was performed using the migration under agarose technique. To test the effect of B(1) receptor agonists, each assay was carried out overnight at 37 degrees C in 5% CO(2)-95% air on neutrophils primed with 1 ng/ml interleukin-1beta. Simultaneous experiments were performed using unprimed cells or cells challenged with formyl-Met-Leu-Phe (fMLP). A clear chemotactic activity was observed when primed neutrophils were challenged with Lys-des[Arg(9)]-bradykinin (LDBK) or des[Arg(9)]-bradykinin at 10(-10) M but not when unprimed cells were used. A reduction in the chemotactic response was observed after priming of cells in the presence of 0.5 mM cycloheximide and 10 mug/ml brefeldin A, suggesting that some protein biosynthesis is required. Techniques such as reverse transcriptase-polymerase chain reaction and in situ hybridization confirmed the expression of the B(1) receptor mRNA, and immunocytochemistry and autoradiography demonstrated the expression of the B(1) receptor protein. In contrast to other chemoattractants such as fMLP, cytosolic intracellular calcium did not increase in response to the B(1) receptor agonist LDBK. A generation of kinin B(1) receptor agonists during the early phase of acute inflammation may favor the recruitment of neutrophils to the inflammatory site.

Upregulation of tissue kallikrein, kinin B1 receptor, and kinin B2 receptor in mast and giant cells infiltrating oesophageal squamous cell carcinoma

BACKGROUND

The mitogenic kinin peptides formed by the serine protease, tissue kallikrein (TK1), stimulate the proliferation of tumour cells and, by increasing vascular permeability, enhance metastasis. Oesophageal mucosal epithelial cells are derived from the epithelial cell germ layer, which expresses the kallikrein-kinin cascade.

AIM

To determine the cellular distribution of active TK1, prokallikrein, and the kinin B(1) and B(2) receptors in oesophageal carcinoma by immunocytochemistry and in situ hybridisation (ISH).

METHODS

Fifty oesophageal specimens (33 biopsies and 17 resections) and 10 control specimens adjacent to tumour or normal oesophageal biopsies were studied. Specific antibodies were used to determine the cellular localisation of TK1, prokallikrein, and the kinin B(1) and B(2) receptors in normal and oesophageal specimens by standard immunohistochemical techniques. The intensity of immunolabelling was quantified by image analysis. Antisense probes for TK1 and the kinin B(1) and B(2) receptors were also used to localise mRNA.

RESULTS

TK1 (active and prokallikrein) was expressed in the mucosa of normal and tumour oesophageal epithelium. In general, expression was highest in activated mast cells, followed by giant tumour cells. Immunolabelling results were confirmed by ISH experiments.

CONCLUSIONS

This is the first demonstration that TK1 and kinin B(1) and B(2) receptors are expressed in oesophageal carcinoma. Because TK1 released from tumour cells enzymatically generates mitogenic kinins from its endogenous substrate, kininogen, it is possible that third generation kinin receptor antagonists, which have been shown to be cytotoxic to cancer cells, may be useful therapeutic agents in this disease.

Expression of the plasma prekallikrein gene: utilization of multiple transcription start sites and alternative promoter regions

The plasma prekallikrein gene is expressed in many different human tissues at distinctly different levels and therefore tissue-specific control of the gene transcription is likely. In this study we demonstrate that transcription of the plasma prekallikrein gene can be initiated at multiple sites, for which at least four different promoters are utilized. A comparison of the genomic and mRNA sequences of mouse plasma prekallikrein revealed that the sequence segment that was formerly regarded as the first exon of the mouse plasma prekallikrein gene consists of three exons, with the first exon localized 14.2 kbp upstream of the translation start. For the rat and human plasma prekallikrein genes, in silico analysis suggested an analogous exon-intron organization. Determination of the transcription start sites showed that in both mouse and human, the proximal and distal regions could be utilized for transcription initiation; however, the proximal region is preferred. A deletion mutation analysis of the proximal promoter region using a 1.7-kbp segment revealed a strong activating region immediately upstream of the known mRNA, followed by both a modest repressor and an enhancer region.

Visualisation of transforming growth factor-β1, tissue kallikrein, and kinin and transforming growth factor-β receptors on human clear-cell renal carcinoma cells

Transforming growth factor-beta1 (TGF-beta1) has a biphasic effect on the growth of renal epithelial cells. In transformed cells, TGF-beta1 appears to accelerate the proliferation of malignant cells. The diverse cellular functions of TGF-beta1 are regulated by three high-affinity serine/threonine kinase receptors, namely TbetaRI, TbetaRII and TbetaRIII. The renal serine protease tissue kallikrein acts on its endogenous protein substrate kininogen to form kinin peptides. The cellular actions of kinins are mediated through B1 and B2 G protein-coupled rhodopsin receptors. Both kinin peptides and TGF-beta1 are mitogenic, and therefore may play an important role in carcinogenesis. Experiments were designed to immunolabel tissue kallikrein, TGF-beta1, TbetaRII, TbetaRIII and kinin receptors using specific antibodies on serial sections of normal kidney and clear-cell renal carcinoma (CCRC) tissue, which included both the tumour and the adjacent renal parenchyma. The essential result was the localisation of tissue kallikrein, kinin B 1 and B 2 receptors and TGF-beta1 primarily on the cell membranes of CCRC cells. In the distal and proximal tubules of the renal parenchyma adjacent to the carcinoma (RPTAC), immunolabelling for tissue kallikrein was reduced, but the expression of kinin B1 and B2 receptors was enhanced. Immunolabelling for TbetaRII and TbetaRIII was more pronounced in the proximal tubules of the tissue adjacent to the carcinoma when compared to the normal kidney. The expression of tissue kallikrein, kinin receptors, and TbetaRII and TbetaRIII may be relevant to the parenchymal invasion and metastasis of clear-cell renal carcinoma.

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

In this study we compare the role of kinin-B1 and B2 receptors during ischaemia/reperfusion of rat pancreas. Our investigations were prompted by the observation that infusion of a kinin-B2 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 kinin-B1 receptor antagonist (CP-0298) alone, or in combination with kinin-B2 receptor antagonist (CP-0597), significantly reduced the number of adherent leukocytes in post-capillary venules. In a chronic model with five days of reperfusion, the continuous application of kinin-B1 receptor antagonist or a combination of kinin-B1 and B2 receptor antagonists markedly reduced the survival rate. In kinin-receptor binding studies kinin-B1 receptor showed a 22-fold increase in expression during the time of ischaemia/reperfusion. Carboxypeptidase M activity was up-regulated 10-fold following two hours of ischaemia and two hours of reperfusion, provided the appropriate specific ligand, des-Arg10-kallidin and/or des-Arg9-bradykinin, was used. The occurrence of kinin-B1 receptor binding sites on acinar cell membranes was demonstrated by micro-autoradiography. With a specific antibody, the localisation of kinin-B1 receptor protein was confirmed at the same sites. In conclusion, we have demonstrated the up-regulation of the pancreatic acinar cell kinin-B1 receptors during ischaemia/reperfusion. The novel functional finding was that antagonism of the kinin-B1 receptors decreased the survival rate in an experimental model of pancreatitis.

Stimulated human neutrophils form biologically active kinin peptides from high and low molecular weight kininogens

Human neutrophils play a pivotal role in acute inflammation. However, their capacity to generate bioactive kinin peptides has not been established as yet. We have examined the ability of neutrophil enzymes to release biologically active kinins in vitro from purified human H- and L-kininogens. Neutrophils isolated from human blood were stimulated with f-Met-Leu-Phe, thrombin, or human immunoglobulin G adsorbed to silica particles. Supernatants were incubated with iodinated kininogens, and polyacrylamide gel electrophoresis analyzed aliquots taken after a range of incubation times. A time-course analysis demonstrated that supernatants from stimulated neutrophils caused a rapid hydrolysis of both substrates, resulting in an accumulation of fragments ranging from 20 to less than 10 kDa. Radioimmunoassay (RIA) revealed that all supernatants were able to generate kinins in vitro. High-performance liquid chromatography of the generated peptides indicated that they had a retention time similar to that of bradykinin and Met-Lys-bradykinin, clearly recognized as kinin peptides when the corresponding fractions were tested by RIA. The kinin-immunoreactive fractions produced lowering of blood pressure and a dramatic increase in venular permeability. Biological activity of the neutrophil-generated kinins was completely abolished by the B2 receptor antagonist HOE140, indicating that over the time-course of the experiments, only kinin B2 agonists appeared to have been generated and that cellular actions of these were mediated by kinin B2 receptors. Together, our results demonstrate that human neutrophil proteases can release kinins from both plasma kininogens, suggesting that these peptides may participate actively during acute inflammation.

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 immunolabeled 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.

Immune responses in cancer

The complex of humoral factors and immune cells comprises two interleaved systems, innate and acquired. Immune cells scan the occurrence of any molecule that it considers to be nonself. Transformed cells acquire antigenicity that is recognized as nonself. A specific immune response is generated that results in the proliferation of antigen-specific lymphocytes. Immunity is acquired when antibodies and T-cell receptors are expressed and up-regulated through the formation and release of lymphokines, chemokines, and cytokines. Both innate and acquired immune systems interact to initiate antigenic responses against carcinomas. A new approach to the treatment of cancer has been immunotherapy, which aims to up-regulate the immune system in order that it may better control carcinogenesis. Currently, several forms of immunotherapy that use natural biological substances to activate the immune system are being explored therapeutically. The various forms of immunotherapy fall into three main categories: monoclonal antibodies, immune response modifiers, and vaccines. While these modalities have individually shown some promise, it is likely that the best strategy to combat cancer may require multiple immunotherapeutic strategies in order to demonstrate benefit in different patient populations. It may be that the best results are obtained with vaccines in combination with a variety of immunotherapy combinations. Another potent strategy may be in combining with more traditional cancer drugs as evidenced from the benefit derived from enhancing the efficacy of chemotherapy with cytokines. Through such concerted efforts, a durable, therapeutic antitumour immune response may be achieved and maintained over the course of a patient's lifespan.

Natural products for cancer prevention: a global perspective

The control of cancer, the second leading cause of death worldwide, may benefit from the potential that resides in alternative therapies. The primary carcinogens stem from a variety of agricultural, industrial, and dietary factors. Conventional therapies cause serious side effects and, at best, merely extend the patient's lifespan by a few years. There is thus the need to utilise alternative concepts or approaches to the prevention of cancer. This review focuses on the many natural products that have been implicated in cancer prevention and that promote human health without recognisable side effects. These molecules originate from vegetables, fruits, plant extracts, and herbs.

Immune responses in cancer

The complex of humoral factors and immune cells comprises two interleaved systems, innate and acquired. Immune cells scan the occurrence of any molecule that it considers to be nonself. Transformed cells acquire antigenicity that is recognized as nonself. A specific immune response is generated that results in the proliferation of antigen-specific lymphocytes. Immunity is acquired when antibodies and T-cell receptors are expressed and up-regulated through the formation and release of lymphokines, chemokines, and cytokines. Both innate and acquired immune systems interact to initiate antigenic responses against carcinomas. A new approach to the treatment of cancer has been immunotherapy, which aims to up-regulate the immune system in order that it may better control carcinogenesis. Currently, several forms of immunotherapy that use natural biological substances to activate the immune system are being explored therapeutically. The various forms of immunotherapy fall into three main categories: monoclonal antibodies, immune response modifiers, and vaccines. While these modalities have individually shown some promise, it is likely that the best strategy to combat cancer may require multiple immunotherapeutic strategies in order to demonstrate benefit in different patient populations. It may be that the best results are obtained with vaccines in combination with a variety of immunotherapy combinations. Another potent strategy may be in combining with more traditional cancer drugs as evidenced from the benefit derived from enhancing the efficacy of chemotherapy with cytokines. Through such concerted efforts, a durable, therapeutic antitumour immune response may be achieved and maintained over the course of a patient's lifespan.

Genealogy, expression, and cellular function of transforming growth factor-beta

The transforming growth factor-beta (TGF-beta) gene superfamily expresses a large set of structurally and functionally related polypeptides. Three TGF-beta isoforms are regulated by specific genes and have been identified in mammals (TGF-beta1, -beta2, and -beta3). All three-protein isoforms are observed abundantly during development and display overlapping and distinct spatial and temporal patterns of expressions. Each isoform plays a distinct role, the nature of which depends on the cell type, its state of differentiation, and growth conditions, and on the other growth factors present. TGF-beta regulates many of the processes common to both tissue repair and disease, including angiogenesis, chemotoxins, fibroblast proliferation and the controlled synthesis, and degradation of matrix proteins, such as collagen and fibronectin. This review will examine the genealogy and mode of actions of TGF-beta on the cell types involved in inflammation and repair, as well as in carcinoma.

Visualization of the sequential changes in immunolabelled tissue kininogenase which accompany follicular development and luteinization of angiogenic granulosa cells of the ovary

The serine protease, tissue kininogenase (kallikrein), belongs to a unique family of enzymes that cleaves the decapeptide, kallidin, from the endogenous substrate kininogen. By analysis of genealogy patterns, rat KLK gene family members have been detected in ovarian luteinizing granulosa cells of both gonadotrophin-treated and nontreated control rats. Preliminary experiments suggest that when granulosa and endothelial cells are co-cultured, granulosa cells participate in the formation of vascular capillary tubes. This inherent capacity of granulosa cells to behave and respond like endothelial cells may be of importance in the aetiology of ovarian angiogenesis, which drives new blood vessel formation in the ovary. Recently, we demonstrated that tissue kininogenase showed intense immunolabelling in angiogenic endothelial cells isolated from bovine mature and regressing corpora lutea. Therefore, the question to answer was whether granulosa cells possess the same capacity to express the kallikrein-kinin cascade as do microvascular endothelial cells. As a first step, experiments were designed to determine the expression and visualization of tissue kininogenase (both active and pro-forms) as well as kininogen and kinin receptors in granulosa cells of different developmental stage and segments of the ovarian follicle by immunoperoxidase, fluorescent microscopy (confocal) and in situ hybridization.

Expression of the tissue kallikrein-kinin cascade in granulosa cells of the ovary

The serine protease, tissue kininogenase (kallikrein), belongs to a unique family of enzymes that cleaves the decapeptide, kallidin, from the endogenous substrate kininogen. By analysis of genealogy patterns rat KLK gene family members have been detected in ovarian luteinizing granulosa cells of both gonadotrophin-treated and non-treated control rats. Recently, we demonstrated that tissue kininogenase showed intense immunolabeling in angiogenic endothelial cells isolated from bovine mature and regressing corpora lutea. Therefore, the question to answer was whether granulosa cells associated with ovarian vascularization possess the same capacity to express the kallikrein-kinin cascade as do microvascular endothelial cells. As a first step, experiments were designed to determine the expression and visualization of tissue kininogenase (both active and pro forms) as well as kininogen and kinin receptors in granulosa cells of different developmental stages and segments of the ovarian follicle by immunoperoxidase assay, confocal fluorescent microscopy and in situ hybridization.

Endothelins: vasoactive modulators of renal function in health and disease

Vasoactive autocoids with directly opposing actions on the renal vasculature, glomerular function, and in salt and water homeostasis have been demonstrated in the kidney. In the renal cortex, endothelin (ET)-1 and angiotensin-II cause vasoconstriction, decreasing renal blood flow, and glomerular filtration rate, whereas bradykinin and atrial natriuretic peptide cause vasodilation and increase glomerular capillary permeability. ET-1 causes vasoconstriction of the afferent and efferent arteries and outer medullary descending vasa recta, thereby decreasing vasa recta and papillary blood flow, while bradykinin has the opposite effect. ET-1 stimulates cell proliferation, increasing the expression of several genes, including collagenase, prostaglandin endoperoxidase synthase, and platelet-derived growth factor. ET-1 promotes natriuresis via the ET-B receptor, causing down-regulation of the epithelial Na(+) channel in the renal tubule. Thus, ETs affect three major aspects of renal physiology: vascular and mesangial tone, Na(+) and water excretion, and cell proliferation and matrix formation.

Expression of tissue kallikrein and kinin receptors in angiogenic microvascular endothelial cells

Angiogenesis is the sprouting of new capillary blood vessels from pre-existing ones. The kinin family of vasoactive peptides, formed by the serine protease tissue kallikrein from its endogenous multifunctional protein substrate kininogen, is believed to regulate the angiogenic process. The aim of this study was to determine the expression of tissue kallikrein and kinin receptors in an in vitro model of angiogenesis. Microvascular endothelial cells from the bovine mature and regressing corpus luteum were used only if they reacted with known endothelial cell markers. At first the cultured endothelial cells began sprouting, and within four weeks formed three-dimensional, capillary-like structures. Immunolabelling for tissue prokallikrein and the mature enzyme was intense in the angiogenic endothelial cells derived from mature corpora lutea. Immunoreactivity was lower in non-angiogenic endothelial cells and least in angiogenic endothelial cultures of the regressing corpus luteum. Additionally, using specific antisense DIG-labelled probes, tissue kallikrein mRNA was demonstrated in cells of the angiogenic phenotype. Immunolabelled kinin B2 receptors, but not kinin B1 receptors, were visualised on angiogenic endothelial cells. Our results suggest an important regulatory role for kinins in the multiple steps of the angiogenic cascade that may occur in wound healing and cancer cell growth.

Kallikrein and kinin receptor genes

Recent evidence increasingly supports the view that kinins exercise an important regulatory control in inflammation and in the growth and proliferation of cancer cells. The induction of tissue kallikrein (TK) gene results in either increased or new expression of this protease, resulting in an increased capacity to form kinins. The cellular actions of kinins are initiated and controlled by kinin B1 and B2 receptors. This review collates in detail current knowledge on the molecular profile and status of TK (hKLK1, hKLK2, and hKLK3) and the kinin B1 and B2 receptor genes. The development of TK inhibitors, as well as kinin receptor antagonists, for use in immune-modulated disorders and in tumours may provide a new generation of drugs of therapeutic value.

Identification of immunoreactive tissue prokallikrein on the surface membrane of human neutrophils

Putative binding sites for prokallikrein, the endogenous zymogen of the vasoactive and pro-inflammatory tissue kallikrein-kinin system, were recently demonstrated on human neutrophils. However, the occurrence and distribution of neutrophil-bound prokallikrein itself have so far not been examined. In this study, a specific anti-peptide antibody directed against the propart of the zymogen was used to localize the kallikrein precursor by confocal laser-scanning microscopy on unstimulated human blood neutrophils. Our results describe, for the first time, the presence of tissue prokallikrein on the membrane of circulating neutrophils. Immunoreactive prokallikrein was associated into punctate clusters occupying the external surface of the neutrophil membrane and, after addition of exogenous zymogen, immunolabeling was enhanced four-fold. In contrast, only moderate immunoreactivity to prokallikrein was observed intracellularly. These results suggest that resting neutrophils provide a circulating platform for tissue prokallikrein whose surface density may be upregulated as part of the inflammatory process.

Urinary levels of tissue kallikrein in the South African Black and Indian hypertensives

It is accepted that Black subjects differ from White and Indian hypertensives in their response to hypotensive agents. Black hypertensives in the USA have a lower urinary tissue kallikrein (TK) excretion levels compared to White hypertensives. It has been suggested that Black patients respond better to thiazide diuretics compared to beta-blockers because thiazides increase whereas beta-blockers decrease tissue kallikrein excretion. This study compares the excretion of urinary TK in Black and Indian hypertensive and normotensive subjects. Urinary TK levels were measured with the selective, synthetic peptic substrate with the sequence of H-D-Val-Leu-Arg-pNA. Ten hypertensive patients on placebo therapy and 10 normotensive Black and Indian subjects provided three samples at weeks 0, 2 and 4 for the determination of urinary TK. The results were analysed using analysis of variance to compare the two racial groups. There were no significant differences in urinary TK values of the three bi-weekly individual samples. Urinary tissue kallikrein values (ng TK/microg protein) in Indian hypertensives were in general lower than Black hypertensives.

Endothelin-1 and endothelin receptor status in kidney transplants undergoing acute rejection

Endothelin-1 (ET-1) is a potent vasoconstrictor with vasopressor and mitogenic effects. Blood samples were collected from 21 renal transplant patients undergoing acute rejection at the time of diagnostic kidney biopsy: there were 20 men and one woman, mean age 35.6 years. All patients were on triple immunosuppressive therapy with cyclosporine A, azathioprine and methylprednisolone. Twenty living kidney donors pre-uninephrectomy (11 men and nine women, mean age 34 years) served as controls. Control kidney was obtained from fresh autopsy material and normal kidney tissue from nephrectomies for malignancy. Mean plasma ET-1 was significantly increased at 1.56 +/- 0.2 pg ml(-1) during acute rejection compared to 0.74 +/- 0.06 pg ml(-1) in donors (p = 0.0009 unpaired t-test). ET(A) receptor immunolabelling was visualised in distal tubules and collecting ducts with minimal labelling in the glomeruli and blood vessels of control kidney tissue ET(A) receptor labelling was similar in kidney biopsies with acute rejection. ET(B) receptor immunolabelling was significantly increased in glomeruli (p = 0.002) and decreased in distal tubules (p = 0.004) in kidneys with acute rejection compared to control kidney tissue. While these findings may account for the oedema and hypertension observed during acute rejection, the exact significance needs to be studied further.

Hydrolysis of kininogens by degranulated human neutrophils and analysis of bradykinin as chemotactic factor for cells isolated from peripheral blood

Human neutrophils play a pivotal role in acute inflammation including the regulation of vascular permeability. We have examined the capacity of neutrophil enzymes to hydrolyse human kininogens in vitro and have also explored the potentiality of bradykinin to induce chemotactic migration on neutrophils isolated from peripheral blood. Isolated neutrophils were stimulated with either f-Met-Leu-Phe, thrombin or silica particles coated with human IgG. Neutrophil enzymes obtained by degranulation produced, after 45 min of incubation with high and low molecular weight kininogens, the complete transformation of both proteins in polypeptides ranging from 20 to less than 10 kDa in molecular mass. Supernatants obtained from nonstimulated neutrophils did not modify the molecular size of kininogens. The assay used to test the chemoattractant capacity of synthetic bradykinin on human neutrophils showed that this peptide has no chemotactic activity on cells isolated from healthy subjects. Our results show that stimulation of human neutrophils with opsonized silica, thrombin and the chemotactic peptide f-Met-Leu-Phe induces release of kininogen-hydrolyzing enzymes from these cells.

Kinin receptors are expressed in human astrocytic tumour cells

Tissue kallikrein (TK) is known to be present in several tumours in which increased KLK1 (TK) gene expression has been demonstrated. By degrading components of the extracellular matrix, TK may facilitate tumour proliferation and invasion. The vasodilatory effect of the bioactive kinin peptides causes an increase in vascular permeability, thereby enhancing metastasis. Since kinins act by receptor-linked signal transduction mechanisms, the aim of this study was to elucidate the localization and expression of kinin B1 and B2 receptors in surgical samples of human astrocytic tumours. Tumour tissue collected was processed for light, confocal and electron microscopy (EM) and RNA extraction. The mean high intensity of immunolabeling in tumour cells was quantified in pixels per square micrometer using the Analysis 2.1 Prosystem (Soft-Imaging Software, Germany, 1996). The ultrastructural localization of B1 and B2 kinin receptors was performed on ultrathin sections of the resin-embedded tissue, using immunogold-labeled probes. In the human brain, immunoreactive B2 occurs in cortical neurones but not in glial cells, and immunolabeling for B1 receptors is absent in cortical areas. In the present study, in all of the tumours studied so far, immunolabeling for B2 (28.42 pixels/microm2, n = 12) and B1 (14.07 pixels/ microm2, n = 10) was observed on the astrocytic cells. Immunoreactive kinin receptors were also present in endothelial cells of the stromal blood vessels. At EM, the average number of immunogold particles was 14 for B2 receptors and eight for B1 receptors. The immunoreactive B2 receptors were located closer to the periphery of the tumour cells while B1 immunolabeling was observed throughout the cell.