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.

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.

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.

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.

Cellular visualization of tissue prokallikrein in human neutrophils and myelocytes

The vasoactive peptides bradykinin and kallidin (lysyl-bradykinin) have been implicated in diapedesis, a cellular process by which neutrophils migrate through endothelial cell gap junctions. The kinin peptides are released from their precursor moiety, kininogen, by the specific action of endoproteinases, the kallikreins. Kininogens have been demonstrated on the surface of neutrophils, and the presence of a competent processing enzyme such as tissue prokallikrein in neutrophils has been postulated, but firm evidence for this is still lacking. We have raised antibodies to a synthetic peptide that is a sequence copy of the activation segment of human TK and demonstrated that the anti-peptide antibodies specifically recognized the zymogen but not the active form of kallikrein. Using these anti-peptide antibodies, we showed by Western blotting, immunocytochemistry and electron microscopy that the tissue prokallikrein antigen was localized in neutrophils and their precursor cells, the myelocytes. We further demonstrated by in situ hybridization the presence of tissue kallikrein mRNA in the mature neutrophils and myelocytes. Our findings lend credence to the hypothesis that upon release and activation, neutrophil-borne TK acts on cell-associated kininogens to trigger the release of kinins, which may open endothelial gates for neutrophil diapedesis.

Not more than three tissue kallikreins identified from organs of the guinea pig

The large and varied multigene families of tissue kallikreins of rat and mouse are considered to selectively release as many bioactive peptides. In order to determine whether a similar family of enzymes is expressed in the organs of the guinea pig purification studies were performed. Tissue kallikreins from the submandibular gland, coagulating gland/prostate complex and the pancreas were separated by affinity chromatography on benzamidine-Sepharose. Amino-terminal sequences, the patterns of hydrolysis rates of a number of peptide p-nitroanilides, inactivation rates by active site-directed irreversible inhibitors, specific kininogenase activities and types of kinin released were used to probe the identity of the isolated enzymes. Guinea pig tissue kallikreins 1 and 2 have been reported previously. In the present study we have identified a third type, designated tissue kallikrein 1a because of its sequence similarity to kallikrein 1, which differs from the latter in the catalytic properties. The inferred occurrence of not more than two or three independent tissue kallikrein genes in the guinea pig contrasts with the varied family of enzymes expressed by the large number of such genes present in rats and mice. Expression in the guinea pig (and also in humans) of only a small number of tissue kallikreins makes specific processing of a multitude of biologically active peptides by such enzymes unlikely.

Traumatic brain contusions: a clinical role for the kinin antagonist CP-0127

Focal cerebral contusions can be dynamic and expansive, leading to delayed neurological deterioration. Due to the high mortality associated with such cerebral contusions, our standard practice had evolved into evacuating contusions in patients who had a deterioration in level of consciousness, lesions > 30 cc and CT suggestion of raised ICP. Experimental brain edema studies have implicated kinins in causing 2 degrees brain swelling. CP-0127 (Bradycor), a specific bradykinin antagonist, has been found to reduce cerebral edema in a cold lesion model in rats. In a randomized, single blind pilot study, a 7 day infusion of CP-0127 (3.0 micrograms/kg/min) was compared to placebo in patients with focal cerebral contusions presenting within 24-96 hours of closed head injury with an initial GCS 9-14. The ICP, GCS, and vital signs were monitored hourly. The total lesion burden (TLB) was measured on serial CT scans. There were no differences in age, baseline GCS, TLB, initial ICP, or laboratory findings between the two groups (n = 20). The mean (+/- s.d.) rise in peak ICP from baseline was greater in the placebo group than with CP-0127 (21.9 +/- 4.7 vs 9.5 +/- 2.0, P = 0.018). In addition, the mean reduction in GCS in the placebo group was significantly greater than in the CP-0127 group (4 +/- 1.0 vs 0.6 +/- 0.4, P = 0.002). Significantly raised ICP and clinically significant neurological deterioration occurred in 7/9 patients on placebo (77%) and only in 1 patient (9%; n = 11) on CP-0127, mandating surgery (P = 0.005). There were no adverse drug reactions, significant changes in vital signs or variations in the laboratory values. The cerebral perfusion pressure was adequately maintained in all patients irrespective of therapy. These preliminary results with CP-0127 provide supporting evidence that the kinin-kallikrein system could be involved in cerebral edema. In this study, treatment with CP-0127 appeared to alter the natural history of traumatic brain contusions by preventing the 2 degrees brain swelling. In addition, CP-0127 obviated the need for surgery in the majority of treated patients. CP-0127 could act on the cerebral vasculature to limit dys-autoregulation and brain swelling or on the blood brain barrier to reduce cerebral edema.

Pathophysiology of the kallikrein-kinin system in mammalian nervous tissue

The nervous system and peripheral tissues in mammals contain a large number of biologically active peptides and proteases that function as neurotransmitters or neuromodulators in the nervous system, as hormones or cellular mediators in peripheral tissue, and play a role in human neurological diseases. The existence and possible functional relevance of bradykinin and kallidin (the peptides), kallikreins (the proteolytic enzymes), and kininases (the peptidases) in neurophysiology and neuropathological states are discussed in this review. Tissue kallikrein, the major cellular kinin-generating enzyme, has been localised in various areas of the mammalian brain. Functionally, it may assist also in the normal turnover of brain proteins and the processing of peptide-hormones, neurotransmitters, and some of the nerve growth factors that are essential for normal neuronal function and synaptic transmission. A specific class of kininases, peptidases responsible for the rapid degradation of kinins, is considered to be identical to enkephalinase A. Additionally, kinins are known to mediate inflammation, a cardinal feature of which is pain, and the clearest evidence for a primary neuronal role exists so far in the activation by kinins of peripherally located nociceptive receptors on C-fibre terminals that transmit and modulate pain perception. Kinins are also important in vascular homeostasis, the release of excitatory amino acid neurotransmitters, and the modulation of cerebral cellular immunity. The two kinin receptors, B2 and B1, that modulate the cellular actions of kinins have been demonstrated in animal neural tissue, neural cells in culture, and various areas of the human brain. Their localisation in glial tissue and neural centres, important in the regulation of cardiovascular homeostasis and nociception, suggests that the kinin system may play a functional role in the nervous system.

Cellular orientation of atrial natriuretic peptide in the human brain

Many peptide hormones and neurotransmitters have been detected in human neuronal tissue. The localisation of atrial natriuretic peptide (ANP) in the human brain was considered to be both interesting and relevant to the understanding of neurochemistry and brain water-electrolyte homeostasis. This vasoactive peptide hormone has been localised in rat and frog neuronal tissue. In the present study, we report the immunohistochemical localisation of ANP in autopsy samples of human brain tissue employing the avidin-biotin-peroxidase complex technique, using an antibody against a 28 amino acid fragment of human ANP. The most intense staining of immunoreactive ANP was detected in the neurones of preoptic, supraoptic and paraventricular nuclei of the hypothalamus, epithelial cells of the choroid plexus and ventricular ependymal lining cells. Immunoreactive neurones were also observed in the median eminence, lamina terminalis, infundibular and ventromedial nuclei of the hypothalamus, and in neurones of the brain stem, thalamic neurones and some neurones of the caudate nucleus. The network of ANP cells in numerous hypothalamic centres may regulate the salt and water balance in the body through a hypothalamic neuro-endocrine control system. ANP in the brain may also modulate cerebral fluid homeostasis by autocrine and paracrine mechanisms.

Urinary levels of tissue kallikrein in black and Indian hypertensives and their implications for therapy

It is accepted that blacks differ from white and Indian hypertensives in their response to hypotensive agents. Black hypertensives in the USA have lower urinary tissue kallikrein (TK) excretion levels than white hypertensives. It has been suggested that blacks respond better to thiazide diuretics than to beta-blockers because thiazides increase TK excretion whereas beta-blockers decrease it. 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 3 samples at weeks 0, 2 and 4 for the determination of urinary TK. The results were analysed and analysis of variance was used to compare the two racial groups. There were no significant differences in urinary TK values of the three biweekly individual samples. Urinary TK values (ng TK/microgram protein) in Indian hypertensives were generally lower than in black hypertensives.

Kinin receptors on human neurones

Knowledge of the distribution of kinin receptors in the human brain will aid our understanding of the role of kinins in neurophysiology. Furthermore, induction of the kinin B1 receptor may be important in the pathogenesis of neural diseases. Using polyclonal antibodies directed to specific regions of the B1 and B2 kinin receptors and standard immunolabelling techniques, we report on the localisation of these receptors on neurones in specific areas of the human brain. B2 bradykinin receptors are present in neurones of the brain stem, basal nuclei, cerebral cortex, thalamus and hypothalamus. B2 immunolabelling was also observed in the endothelial lining of the superior sagittal dural sinus and ependyma of the lateral and third ventricles. B1 kinin receptors have been localised on neurones of the thalamus, spinal cord and hypothalamus. Although binding of labelled bradykinin to neuronal membranes has been demonstrated, this is the first conclusive evidence for the existence of immunoreactive B1, and further confirmation of B2 receptors on human neurones.

Tissue kallikrein in transplant kidney

Literature survey, thus far, has shown a decrease in the excretion of urinary tissue kallikrein (TK) in transplant patients with a further reduction of the enzyme during episodes of acute rejection. The study aims were to compare, at cellular and subcellular levels, the localisation of tissue kallikrein in biopsies of the transplant kidney to autopsy derived normal renal tissue. Renal biopsies from eighteen transplant patients with deteriorating renal function were obtained. Immunolabelling for tissue kallikrein, using a polyclonal goat anti-TK, antibody raised against recombinant TK, was performed following routine enzymatic, immunofluorescence and electron microscopic techniques. In normal kidney tissue, TK was immunolocalised in the distal connecting tubules and collecting ducts. By comparison the renal transplant tissue showed a reduction in the intensity of label, but maintained the sites of localisation. In the sections examined by electron microscopy, although TK was confined mainly at the luminal side of the cell, some label was noted along the basolateral membranes. In the transplant kidneys, there was a reduction in the overall number of gold particles counted, which correlated with the decreased intensity observed on immunocytochemistry. In addition, there was a shift to a basolateral orientation of the immunolabel. Acute rejection is characterised by oedema, tubulitis and vasculitis. Destruction of the tubule cells and leakage of TK into the interstitial tissue space and the resultant effect of the formed kinins on renal capillary vasculature could explain the observed renal parenchymal oedema and transplant rejection.

The evaluation of tissue kallikrein in Helicobacter pylori-associated gastric ulcer disease

Helicobacter pylori (Hp) associated ulcer disease is a common form of gastric disorder involving mucosal damage and invasion of the mucosa by polymorphic inflammatory cells with concomitant changes in the epithelial cell structure. The bacteria are thought to adhere by specific junction zones to the epithelial cell surface resulting in the degeneration of the mucosal layer. Our study was undertaken to examine the relative status of tissue kallikrein (TK) in antral and fundic biopsies, endoscopically obtained from 10 patients suspected of having gastric disorders. For histological evidence of inflammation the tissue was stained with hematoxylin and eosin and classified as mild, active, chronic and chronic active gastritis. Hp infection was determined by Giemsa staining. For localisation of TK, slide-mounted tissue sections were subjected to PAP and immunofluorescent staining using a goat anti-human TK IgG antibody. The results revealed that in the antral control tissue, removed during partial antractomy, TK was immunovisualised along the luminal border of the deep pyloric glands. The surface epithelia and superficial glands showed no labelling. The fundic control tissue revealed an absence of TK in the superficial and surface epithelial glands, but was positive in the parietal cells. The fundic biopsy specimens showed similar immunoreactivity in these areas. By contrast, in the inflammed pyloric mucosa, there was a shift of TK localisation to the basal part of the glandular cells and there was also expression of TK in the superficial glands that showed histological evidence of regeneration. In the fundic biopsies there was no change observed in the sites of TK localisation (similar to control tissue). It was observed, that even though 8 of the 10 subjects exhibited Hp infection, the inflamed mucosa showed no discernable difference in the staining patterns between the infected and non-infected tissue sections. Our findings suggest an important role for a B1/B2 kinin antagonist in patients with gastritis.

Kinin receptor status in normal and inflammed gastric mucosa

No documented studies have been reported on the presence of B1 and B2 kinin receptors in the mammalian gastric mucosa. This first study aimed to immunolocalise sites of B1 and B2 kinin receptors in the human pyloric gastric mucosa and to evaluate its role in gastritis. Biopsies were obtained from patients with dyspepsia during endoscopic examination of the patient. The diagnosis and grading of the gastritis was performed on histological examination. Sections were immunostained for both B1 and B2 receptors using rabbit anti-human B1 and B2 kinin receptor antibodies. Control tissue was obtained from partial gastrectomy specimens, following surgical excision of the antrum for duodenal ulcers. The control antrum tissue showed strong immunoreactivity for kinin B2 receptors with positivity noted along the luminal border, at the base of the mucous and stem cells. The B1 receptor was not immunolocalised. Biopsies of all five patients with gastritis showed a decrease in immunolabelling of the B2 receptor and an induction of the B1 receptor especially in regenerating cells. In gastritis there is destruction of the normal mucosal glandular architecture with subsequent regeneration of the epithelial cells. The pyloric glands are infiltrated by acute inflammatory cells that cause crypt abscesses with loss of the epithelial cell membranes. This may explain the reduction in the immunolocalisation of the B2 kinin receptors and the induction of the B1 receptors in active gastritis. Follow up studies after treatment of the inflammation with a combination of B1/B2 kinin receptor antagonists are indicated.

Immunolocalization of bradykinin receptors on human synovial tissue

Kinins have been implicated in the pathogenesis of experimental and clinical inflammatory arthritis. Previous studies have reported increased amounts of plasma and tissue kallikreins in synovial fluid, raised kinin levels and an upregulation of kinin B2 receptors on synovial fluid neutrophils in rheumatoid arthritis. Bradykinin binding sites have been identified on human synovial cells by autoradiographic localization and Scatchard analysis. This study was undertaken to localize immunohistochemically kinin B1 and B2 receptors on human synovial tissue. Synovial tissue was obtained at the time of joint replacement surgery or arthroscopic synovectomy in six patients (two RA, two OA and two with avascular necrosis). Tissue sections were immunolabelled for kinin B1 and B2 receptors and viewed by light and confocal microscopy. No immunolabelling of the kinin receptors was observed in the method controls. In all patients labelling for kinin B2 receptors was observed in the synovial lining cells, fibroblasts and endothelial lining cells of blood vessels. There was no immunolabelling for kinin B1 receptors in all samples. These findings further support a role for the B2 receptors in joint diseases. There did not appear to be an induction of the kinin B1 receptor in human synovial tissue obtained from patients with chronic arthritis. However, further studies are required to assess the role of B1 receptors in active joint inflammation.

Kinin receptors in human vascular tissue: their role in atheromatous disease

Using samples of many human blood vessels, obtained at autopsy and specific antibodies directed to peptide sequences of the kinin B1 and B2 receptors, we demonstrate the localisation of these receptors within the human vascular system using standard immunolabelling techniques. In large elastic arteries and veins, kinin receptors are present only in the endothelial cells whereas in all muscular arteries and arterioles, these receptors are present in both the endothelial and smooth muscle cells. The identification of kinin receptors in human blood vessels confirms that kinins may modulate both vascular permeability and contractility. The incidental finding at histology, of patchy atheromatous disease in the coronary, femoral, vertebral and pericallosal arteries, assisted in elucidating the role of these receptors in the commonest disease affecting human blood vessels. Intense labelling for B1 receptors was observed in the endothelial cells, foamy macrophages, inflammatory cells and fibroblasts within the thickened intima of the plaque as well as in smooth muscle cells of the underlying tunica media. Immunoreactive B2 receptors were also observed in these cells but with reduced intensity. The intense immunolabelling of B1 receptors in these regions suggest that these may be induced by atheromatous disease and may have therapeutic importance for the B1 receptor antagonists.

Generation of kinins in synovial fluid from patients with arthropathy

An enzyme-linked immunosorbent assay method is described for the measurement of kinin formation in synovial fluid from patients with rheumatoid and osteoarthritis (RA and OA). Basal kinin concentrations were less than 6 ng/ml in synovial fluid collected in the presence of inhibitors of kinin forming (kininogenase) and kinin metabolising (kininase) enzymes. During incubation of synovial fluid in the presence of kininase inhibitors alone, kinins were produced rapidly over the first 10 min, but production ceased completely within 30 min due to inhibition of the endogenous kininogenases; the rate of kinin generation during the early rapid phase correlated well with the plateau kinin concentration. Plateau kinin levels in synovial fluid from 15 patients with OA and RA ranged from 98 to 427 ng/ml, with a median value of 148 ng/ml. This study demonstrates clearly that synovial fluid from arthritis patients has the capacity to produce kinins. Although the number of patients was small, the amount of kinin generated in vitro varied over a wide range and a relationship between intra-articular kinin formation and clinical features may become apparent in a larger group of patients. The technique could also be used to investigate other biological systems in which a role has been proposed for kinins.

Changes in urinary tissue kallikrein excretion in black African women with hypertensive disorders of pregnancy

The aim of this study was firstly to establish whether tissue kallikrein (TK) was involved in the aetiology of hypertensive disorders of pregnancy. Secondly, to assess whether tissue kallikrein:creatinine ratios may differentiate normotensive pregnant women from those with hypertensive disorders of pregnancy and have a predictive value. Random untimed urine samples were collected from all women (n = 264) recruited to this study. Urine specimens were analyzed for urinary tissue kallikrein using a selective, synthetic chromogenic tripeptide substrate (H-D-Val-Leu-Arg-pNA). Urinary creatinine levels were measured using standard methods. There was a significant difference in the excretion of urinary tissue kallikrein between normotensive pregnant women (2.91 ng TK/microgram protein) and women with mild (2.52 ng TK/microgram protein; p < 0.0001) and severe (1.53 ng TK/microgram protein; p < 0.0001) hypertension in pregnancy. No statistical difference was observed with regard to urinary tissue kallikrein excretion between normotensive pregnant and normotensive non-pregnant women (2.87 ng TK/microgram protein; p = 0.16). A positive correlation was observed between the diastolic blood pressure and urinary tissue kallikrein excretion in women with hypertensive disorders of pregnancy. When compared to the normotensive pregnant group, the urinary kallikrein:creatinine ratios were significantly lower in the mild (0.6 versus 0.3; p < 0.0001) and severe (0.6 versus 0.12; p < 0.0001) hypertensive groups. The urinary creatinine excretion was significantly higher in the mild (9.55 +/- 2.6 mmol/l; p < 0.0001) and in severe (15.62 +/- 5.48 mmol/l; p < 0.0001) hypertensives when compared to normotensive pregnant values (5.65 +/- 2.6 mmol/l). The reduced urinary tissue kallikrein excretion in hypertensive disorders of pregnancy may be a significant factor in the development of the hypertension in pregnancy. Measurement of urinary tissue kallikrein: creatinine ratios may represent a simple and practical predictive test to differentiate women with hypertensive disorders of pregnancy from normotensive pregnant women.

Localisation of tissue kallikrein in the kidney of black African women with early onset pre-eclampsia: a pilot study

Increased renal production of vasodilator mediators like kinins would counteract the vasospasm of pre-eclampsia. This study examines the cellular localisation of tissue kallikrein (TK), the potent kinin forming enzyme within the nephron of patients with early onset pre-eclampsia. Using the peroxidase-antiperoxidase immunoenzyme complex, TK was immunolocalised in the principal cells of the distal connecting tubule and the cortical collecting duct cells of the distal nephron of control tissue. Moderate reactivity was observed in the epithelial cells lining the Bowmans capsule. In early onset pre-eclampsia, TK was additionally localised in the proximal tubule cells, however, the intensity of reactivity was reduced when compared to that of the distal tubule cells. In patients with hypertension of pregnancy, the occurrence of TK in the proximal tubule suggests either gene induction or emiocytosis of TK.

Immunocytochemical analysis of tissue kallikrein and the kinin moiety in rheumatoid synovial fluid neutrophils

Polymorphonuclear leucocytes (PMNs) from the synovial fluid of patients with rheumatoid arthritis (RA) showed reduced tissue kallikrein and kinin immunoreactivity in comparison with blood PMNs from healthy individuals as judged visually using confocal microscopy. Similarly, synovial fluid PMNs exhibited reduced tissue kallikrein immunoreactivity as compared with blood PMNs from the same RA patients. Blood PMNs stimulated to degranulate in vitro also displayed less immunostaining for tissue kallikrein and kinin than non-stimulated PMNs. By contrast, no difference in kininogen immunostaining was detected between RA synovial fluid PMNs and blood PMNs from healthy people. It is considered that the results support the hypothesis that tissue kallikrein, released from the granules of RA synovial fluid PMNs, cleaves the kinin moiety from multifunctional kininogen protein on the surface of the PMNs.

Translocation of the neutrophil kinin moiety and changes in the regulation of kinin receptors in inflammation

A molecular response to cell injury is the formation of chemotactic mediators that attract neutrophils to sites of inflammation. The question whether neutrophils contribute to circulating levels of kinins was examined in infections and inflammatory disorders. This novel hypothesis was tested using circulating neutrophils harvested from patients with tuberculosis meningitis and pneumonia. These neutrophils showed a distinct loss of only the kinin moiety from the kininogen located on the external surface. A similar loss of the kinin peptide was observed on the synovial fluid neutrophils obtained from the swollen, inflamed joints of patients with rheumatoid arthritis. The intriguing question is whether the circulating neutrophils simply reflect those cells re-entering the circulation from sites of inflammation. Anti-peptide antibodies to the peptide loops of cloned B1 and B2 receptors have provided a powerful probe for the cellular identification of the two kinin receptor families. We report the first localisation of B1 receptors on the basement membranes of bronchopulmonary cells and the surrounding fibrous stroma in transbronchial biopsies taken from patients with interstitial lung disease associated with progressive systemic sclerosis. Although binding of labelled bradykinin to neuronal membranes has been demonstrated, this is the first conclusive evidence for the presence of B1 kinin receptors in the neurons of human hypothalamus, caudate nucleus and the substancia gelatinosa of the spinal cord. Mapping of the B2 receptors in human tissues shows upregulation on the neutrophils gathered from inflamed joints, and absence from cell membranes of acutely rejecting transplant kidney. In addition, B2 receptors have also been demonstrated in neurons of the brain hypothalamus, caudate nucleus and cerebral cortex. Kinin receptor localisations in human tissue has considerable therapeutic implications.

Regional distribution of tissue kallikrein in the human brain

Except for the localisation of tissue kallikrein (TK) in human prolactin secreting adenomas, its apparent deficiency in Alzheimer's disease and presence in human cerebrospinal fluid (CSF), the regional distribution of TK in human brain has not been defined. In this study on human brains collected within 24 h of death, we report on the regional distribution of TK in 24 different brain areas. The presence of TK was determined by its amidase and kininogenase activities, and the cellular localisation by immunocytochemistry. The highest amidolytic activity using the substrate D-ValLeuArg-pNA was recorded with extracts of the choroid plexus and hypothalamus, whereas extracts of the cerebral cortex (5 areas), cerebellum (3 areas), brain stem and thalamus possessed moderate amidolytic activity which correlated with the kininogenase assay. Immunoreactive TK has thus far been visualised in neurones of the hypothalamus, thalamus and reticular areas of the brain stem, as well as in cells of the anterior pituitary and choroid plexus by light and confocal microscopy. The cellular distribution of TK in specific areas suggests a role for TK in the neurones and epithelial cells of the brain. The question whether the functional importance of TK may relate to a particular cell type remains to be elucidated.

Identification and functional importance of plasma kallikrein in the synovial fluids of patients with rheumatoid, psoriatic, and osteoarthritis

OBJECTIVES

To determine and identify, unequivocally, if plasma kallikrein (PK) is present in the synovial fluid of patients with rheumatoid (RA), psoriatic (PA) and osteo (OA) arthritis, and to consider its functional importance in the inflamed joint.

METHODS

Therapeutically aspirated synovial fluids (pooled and individual samples, n = 66) were obtained from patients with arthritis. In addition, serum (n = 14) was collected from RA patients, and saliva (n = 10) and urine (n = 10) from normal individuals. Enzymic (amidase) and immunoreactive activities of PK and its precursor, prokallikrein (PPK), were determined. The presence of PK was assessed by incubation with soya bean trypsin inhibitor (SBTI), and by adsorption with anti-PK antibody linked to Sepharose. An enzyme-linked immunosorbant assay (ELISA) for PK was developed for quantitative measurement of total PK in biological fluids. Enhancement of the PK dose-response by RA synovial fluid made it necessary to remove RF from synovial fluids before determination of PK by ELISA.

RESULTS

Amidase activity was demonstrated in synovial fluid pools and shown to be inhibited completely by SBTI, and removed by prior treatment with anti-PK Sepharose. Total PK activity (PK + PPK) from individual synovial fluid specimens did not differ significantly between patients with RA (median activity 76 mU/g protein), PA (80 mU/g protein) or OA (60 mU/g protein). Similar results were obtained when active PK alone was measured. No correlation was found between active PK or total PK values and the severity score for individual joints. Most of the measured immunoreactivity was removed by adsorption with anti-PK antibody linked to Sepharose.

CONCLUSION

The results support the hypothesis that plasma kallikrein is present in synovial fluid. The enzyme may be important in the pathogenesis of inflamed joints.

A clinicopathological study of collagen sponge as a dural graft in neurosurgery

There is frequently a need for dural grafts to cover defects resulting from retraction, shrinkage, or excision following neurosurgical procedures. Several materials have been evaluated both experimentally and clinically, and then discarded. Collagen, in its various forms, continues to be an area of intense interest. In this study the authors examined the suitability of collagen sponge to effect dural repair. In a 5-year clinical study 102 collagen sponge implants were examined macroscopically and histologically. Graft encapsulation, neomembrane formation, delayed hemorrhage, and foreign body reactions were not found. The porous nature of the collagen sponge encouraged fibroblastic ingrowth and dural repair. Meningocerebral adhesions were present in 11 patients, all of whom had required significant cortical resection or had pia-arachnoid disruption during the initial surgery. Inflammatory cells were seen only in response to infection. Postoperative cerebrospinal fluid leaks developed in only three of 67 patients who underwent an intradural posterior fossa procedure. In a prospective arm of the study involving 459 patients, the wound infection rate using collagen sponge was 6.1%, which compared favorably (p = 0.67) with the 5.7% rate in a similar group of 637 patients in whom collagen sponge had not been used.

Cellular localization of atrial natriuretic peptide and tissue kallikrein in the human hypothalamus

In the kidney, renal atrial natriuretic peptide (ANP) is considered to play an important role in water and salt homeostasis. Immunoreactive ANP in the brain of lower invertebrates, such as the rat, has been shown to be localized in the hypothalamus and septum. Several studies have investigated the possibility of a regulatory system in the brain similar to that of the kidney. Since neuronal function is acutely sensitive to disturbances of the intracranial water and salt balance we have attempted to immunolocalize ANP-containing cells in the normal human hypothalamus, using a polyclonal antiserum specific to ANP. Also, we have observed tissue kallikrein (TK), using a polyclonal antiserum specific to TK, in the same areas as ANP. A regulatory role for TK on prolactin has been suggested as the rationale for the co-localization of these two hormones in human prolactinomas. Therefore, it could be suggested that TK plays a similar role in the processing of precursor ANP in the brain. It is contemplated to examine the status of these peptides in patients with cerebral oedema.

Assembly of contact-phase factors on the surface of the human neutrophil membrane

H-kininogen (HK), a major factor involved in contact-phase activation, was recently immunolocalized on the external surface of human neutrophils. Experiments were, therefore, designed to consider the question of whether the complete assembly of contact factors occurs on the outer surface of the neutrophil membrane. By immunolocalization techniques, and using specific antibodies directed against the various contact factors, we now demonstrate that plasma prekallikrein (PK), factor XI (FXI), and factor XII (FXII) are present on the exterior face of the human neutrophil. Failure to localize HK, PK, or FXI by monoclonal antibodies directed to their reciprocal binding sites, and displacement of PK/FXI by peptide HK31, which mimics the relevant binding site(s) of HK, suggested that prekallikrein and FXI are anchored to the neutrophil membrane through attachment to the kininogen molecule. Probing of the kinin moiety by a specific antibody showed that kininogen molecules bound to the neutrophil cell membrane contain the kinin sequence, which can be released by plasma kallikrein or by tissue kallikrein. Our results led us to the novel conclusion that neutrophils provide a circulating platform for the components of the contact-phase system.

Hyponatremic natriuretic syndrome in tuberculous meningitis: the probable role of atrial natriuretic peptide

Hyponatremia has been reported in up to one third of patients with intracranial disease and has frequently been associated with tuberculous meningitis, often complicated by hydrocephalus. The lowered plasma sodium levels were previously attributed to the syndrome of inappropriate secretion of antidiuretic hormone. A controlled prospective study of 24 patients with tuberculous meningitis and hydrocephalus was carried out. Analyses of serum electrolytes and cerebrospinal fluid were performed. Plasma and cerebrospinal fluid levels of atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) were measured by radioimmunoassay. Fifteen patients were found to be hyponatremic (plasma sodium < 130 mmol/L) and ANP levels of 12 to 1,488 pg/ml were present (median, 26 pg/ml). The remaining 9 patients had normal plasma sodium values between 130 and 145 mmol/L, and in these, plasma ANP values varied between 12 and 21.7 pg/ml (median, 12 pg/ml). The difference between these two groups was not statistically significant. (Control values from patients undergoing myelography were established to range between 12 and 40 pg/ml; median, 14.4 pg/ml.) ANP levels were undetectable in the cerebrospinal fluid in all. Plasma ADH levels in the hyponatremic group were between 7 and 159 pg/ml (median, 40 pg/ml). In the normonatremic group, plasma ADH levels of 25 to 250 pg/ml (median, 29 pg/ml) were obtained. (The controls ranged between 3.6 and 35 pg/ml; median, 10.4 pg/ml). In the hyponatremic group, there was a moderate negative correlation (r = -0.683) between plasma ANP and plasma sodium (P = 0.02). No correlation between plasma ADH and plasma sodium was found (r = -0.168; P = 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)

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

Tissue kallikrein (TK) and alpha 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. alpha 2-Macroglobulin (alpha 2-M) in SF was demonstrated to contain trapped proteases which were still active in amidase assays. Removal of alpha 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 alpha 1-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.

Localization of immunoreactive tissue kallikrein in the seromucous glands of the human and guinea-pig respiratory tree

An immunocytochemical study focused on the cellular localization of tissue kallikrein along the human and guinea-pig respiratory tracts is reported. A strong immunoreactivity for tissue kallikrein was observed in the seromucous glands of the nasal mucosa, trachea, and bronchi. In these glands, the immunostaining was restricted to the serous component of the acinus whereas mucous cells showed no staining. Since no immunoreactivity to kininogen was observed in any of the tissue constituents of the human and guinea-pig respiratory tree, transudation of the substrate from plasma was considered to be the preferred mode of delivery of the kininogen into the bronchopulmonary interstitium and lumen. Our results provide morphological evidence for the well documented presence of tissue kallikrein in bronchial lavage fluids and support the hypothesis that kinins may be one of the more important mediators involved during acute episodes of asthma and rhinitis.

Bioregulatory role of the kallikrein-kinin system in the normal pituitary gland and its tumours

Tissue kallikrein, a serine protease, is present in the prolactin-secreting cells of the normal anterior pituitary gland and pituitary adenomas. It is mainly located in the Golgi apparatus, but is also present in secretory granules. There is a distinct sexual dimorphism, with amount of tissue kallikrein being greater in anterior pituitary tissue from female rats. The intracellular levels of tissue kallikrein are increased by estradiol and in pituitary tumours, and decreased by ovariectomy, dopamine and its agonists. There is preliminary in vitro evidence that tissue kallikrein may be involved in the intracellular processing of the prolactin molecule before secretion. Tissue kallikrein synthesizes kinins which are present in the anterior pituitary and are capable of stimulating prolactin and growth hormone secretion by activating the phosphoinositide second messenger system. Prolactin physiology is uniquely linked to the kallikrein-kinin system in the normal pituitary and its tumours. Tissue kallikrein may have an important role in the pathophysiology of prolactin-secreting pituitary adenomas.

Kinins--key mediators in inflammatory arthritis?

Recent evidence suggests an important role for kinins in the generation of pain, swelling and the cellular damage associated with inflammatory joint disease. Kinins are considered to be pro-inflammatory peptides for a variety of reasons. They stimulate c fibres in the synovium to cause pain and increase extravasation of fluid to produce swelling. Kinins possess the capacity to release neurotransmitters (substance P, acetylcholine) and a second wave of mediators (interleukin-1, tumour necrosis factor, interleukin-8, prostaglandins, leukotrienes). The steady levels and turnover of kinins is regulated by formation (enzymic action of kininogenases on endogenous substrates called kininogens) and by metabolism (kininases, peptidases that hydrolyse kinins). These components of the kinin system can enter the synovial joint space either by transudation from the plasma or from degranulating neutrophils chemotactically attracted into the synovium from which they migrate into the synovial fluid. If kinins are involved, one would expect neutrophil derived mediators of the system to dominate in rheumatoid arthritis and psoriatic arthritis and plasma derived products to be more important in osteoarthritis and gout. But, the question whether any of the functions attributed to each component of the system can be considered to be a primary factor in the cellular pathology of inflamed joints remains to be established. Future investigations, including therapeutic trials with kinin antagonists and kallikrein inhibitors, will need to address the differential role of the kallikreins and kinins in the different types of synovitis, on symptoms of inflammation and on any remedial effects on the progression of tissue damage within the joint.

Tissue kallikrein is associated with prolactin-secreting cells within human growth hormone-secreting adenomas

Tissue kallikrein is a serine protease which may be involved in the intracellular processing of prolactin in the anterior pituitary gland. The expression of tissue kallikrein, in the rat, is promoted by oestrogen and inhibited by dopamine. Human and rat prolactinomas contain markedly increased amounts of tissue kallikrein; this is comparatively reduced if patients are pretreated with the dopamine agonist, bromocriptine, before surgery. Some GH-secreting adenomas are mixed and also contain prolactin-secreting cells. We therefore investigated 27 GH-immunostaining human pituitary adenomas for the presence of immunoreactive tissue kallikrein. Sixteen of the adenomas had positive immunostaining for prolactin; eight of these patients had associated clinical hyperprolactinaemia before the tumour was removed. Tissue kallikrein immunoreactivity was found in ten adenomas, all of which also had prolactin immunopositivity. There was a close relationship between the percentage of cells staining for prolactin and tissue kallikrein but not for GH. A further eight adenomas had patchy positivity, i.e. less than 1% of cells immunostained for tissue kallikrein and six of these also had some prolactin-staining cells. Nine out of eleven purely GH-staining adenomas had no tissue kallikrein immunopositivity, the remaining two showing patchy staining. A review of bromocriptine responsiveness, as assessed by mean GH hormone levels during oral glucose tolerance tests before and after therapy was commenced, indicated that patients with adenomas which stained for prolactin and tissue kallikrein were more likely to respond to bromocriptine than those which failed to do so.