Development of highly sensitive enzyme-linked immunosorbent assays for hepatocyte growth factor/scatter factor (HGF/SF): determination of HGF/SF in serum and urine from normal human subjects

Glut1 expression is increased by p53 reduction to switch metabolism to glycolysis during osteoblast differentiation

The glycolytic system is selected for ATP synthesis not only in tumor cells but also in differentiated cells. Differentiated osteoblasts also switch the dominant metabolic pathway to aerobic glycolysis. We found that primary osteoblasts increased expressions of glycolysis-related enzymes such as Glut1, hexokinase 1 and 2, lactate dehydrogenase A and pyruvate kinase M2 during their differentiation. Osteoblast differentiation decreased expression of tumor suppressor p53, which negatively regulates Glut1 expression, and enhanced phosphorylation of AKT, which is regulated by phosphoinositol-3 kinase (PI3K). An inhibitor of PI3K enhanced p53 expression and repressed Glut1 expression. Luciferase reporter assay showed that p53 negatively regulated transcriptional activity of solute carrier family 2 member 1 gene promoter region. Inhibition of glycolysis in osteoblasts reduced ATP contents more significantly than inhibition of oxidative phosphorylation by carbonyl cyanide m-chlorophenyl hydrazine. These results have indicated that osteoblasts increase Glut1 expression through the down-regulation of p53 to switch their metabolic pathway to glycolysis during differentiation.

Use of polyclonal IgY antibodies to detect serum immune complexes in patients with active hookworm infection

Definitive diagnosis of hookworm infection is usually based on the microscopic detection of eggs in a stool sample; however, several cases display a low or irregular egg output. Serodiagnosis can be a useful tool to identify these cases, but conventional tests do not differentiate past from active infections. The aim of this study was to obtain and apply egg yolk polyclonal immunoglobulin (IgY) antibodies to detect immune complexes (ICs) in serum samples from patients infected with hookworm. Hens were immunized with Ancylostoma ceylanicum saline extract, their eggs were collected and then IgY antibodies were extracted and purified. Antibody purity was tested by 12% sodium dodecyl sulphate polyacrylamide gel electrophoresis and specificity was assessed by immunoblotting and immunofluorescence. IgY production was evaluated by kinetics enzyme-linked immunosorbent assay (ELISA). Sandwich ELISA tested the ability of IgY to detect ICs in serum samples, from which diagnostic parameters were calculated. Antibody responses increased steadily from day 7 to 42. In the immunoblotting assay, IgY recognized two protein complexes. The immunofluorescence assay showed no staining in control samples. The sandwich ELISA presented a very high diagnostic value, with a sensitivity of 90% and a specificity of 86.7%. Our pioneer strategy highlights the potential use of egg yolk IgY as a diagnostic test to detect active hookworm infection.

Detection of Clonorchis sinensis circulating antigen in sera from Chinese patients by immunomagnetic bead ELISA based on IgY

BACKGROUND

Clonorchiasis, caused by Clonorchis sinensis, is widely distributed in Southeast Asia including China. Clonorchiasis is included in control programs of neglected tropical diseases by World Health Organization (WHO) because it is one of the major health problems in most endemic areas. Diagnosis of clonorchiasis plays a key role in the control programs. However, so far, there is no satisfactory method for clonorchiasis because of low sensitivity, poor practicality and high false positivity of available diagnostic tools.

METHODOLOGY/PRINCIPAL FINDINGS

We developed an immunomagnetic bead enzyme-linked immunosorbent assay (ELISA) based on IgY (egg yolk immunoglobulin) against cysteine proteinase of C. sinensis for detection of circulating antigen in serum samples of patients infected with C. sinensis. The polyclonal IgY, coated with magnetic beads, was used as a capture antibody and a monoclonal IgG labeled with horseradish peroxidase as a detection antibody in the IgY-based immunomagnetic bead ELISA system (IgY-IMB-ELISA). The results showed that the sensitivity of IgY-IMB-ELISA was 93.3% (14 of 15) in cases of heavy infection (5000 to 9999 eggs per gram feces, i.e, EPG 5000-9999), 86.7% (13 of 15) in cases of moderate infection (EPG 1000-4999) and 75.0% (9 of 12) in cases of light infection (EPG <1000) of clonorchiasis. Together 36 of total 42 (85.7%) serum samples of human clonorchiasis gave a positive reaction. There was a significant correlation between ELISA optical density and egg counts (EPG) with a correlation coefficient of 0.83 in total 42 patients. There were no positive results in patients with trichinosis (n = 10) or cysticercosis (n = 10). Cross-reactivity was 6.7% (2 of 30) with schistosomiasis japonica and 10.0% (3 of 30) with paragonimiasis, respectively. No positive reaction was found in 20 healthy persons.

CONCLUSIONS

Our findings suggest that IgY-IMB-ELISA appears to be a sensitive and specific assay for detection of circulating antigen in human clonorchiasis.

Trypanosoma cruzi calmodulin: cloning, expression and characterization

We have cloned and expressed calmodulin (CaM) from Trypanosoma cruzi, for the first time, to obtain large amounts of protein. CaM is a very well conserved protein throughout evolution, sharing 100% amino acid sequence identity between different vertebrates and 99% between trypanosomatids. However, there is 89% amino acid sequence identity between T. cruzi and vertebrate CaMs. The results demonstrate significant differences between calmodulin from T. cruzi and mammals. First, a polyclonal antibody developed in an egg-yolk system to the T. cruzi CaM recognizes the autologous CaM but not the CaM from rat. Second, it undergoes a larger increase in the alpha-helix content upon binding with Ca(2+), when compared to CaM from vertebrates. Finally, two classic CaM antagonists, calmidazolium and trifluoperazine, capable of inhibiting the action of CaM in mammals when assayed on the plasma membrane Ca(2+) pump, showed a significant loss of activity when assayed upon stimulation with the T. cruzi CaM.

Mature Hepatocyte Growth Factor/Scatter Factor on the Surface of Human Granulocytes Is Released by a Mechanism Involving Activated Factor Xa

Serum hepatocyte growth factor (HGF) is rapidly increased in patients suffering from various tissue injuries including arterial occlusive diseases. However, the cellular sources of the HGF increase remain largely unknown. In the present study, we showed that bioactive mature HGF is constitutively present on the surface of granulocytes in human peripheral blood. Exogenously added 125I-labeled iodo-HGF efficiently bound to granulocyte surface, whereas only a scarce amount of HGF mRNA was detected in granulocytes, indicating that the mature HGF on granulocytes is likely to be derived from other cell types. Interestingly, treatment of granulocytes with human serum rapidly induced the release of the cell surface-associated HGF. In vivo, thromboplastin injection into mice increased HGF release from transplanted human granulocytes, which was inhibited by the pretreatment with DX9065a, a specific inhibitor of factor Xa. Furthermore, DX9065a also inhibited the serum-induced HGF release from human granulocytes in vitro, suggesting that the HGF-releasing factor(s) in serum is associated with factor Xa activation. Thus, human granulocytes may function as a transporter of HGF in the peripheral blood, releasing HGF at the injured sites caused by blood coagulation, where HGF may promote tissue repair.

Arginine-specific gingipains from Porphyromonas gingivalis stimulate production of hepatocyte growth factor (scatter factor) through protease-activated receptors in human gingival fibroblasts in culture

Cystein proteinases (gingipains) from Porphyromonas gingivalis cleave a broad range of in-host proteins and are considered to be key virulence factors in the onset and development of adult periodontitis and host defense evasion. In periodontitis, an inflammatory disease triggered by bacterial infection, the production of hepatocyte growth factor (HGF) is induced not only by various factors derived from the host, such as inflammatory cytokines, but also by bacterial components. In this study we examined the possible enhanced production of HGF produced by human gingival fibroblasts upon stimulation with gingipains. Arginine-specific gingipain (Rgp) caused a marked production of HGF into the supernatant, the induction of HGF expression on the cell surface, and the up-regulation of HGF mRNA expression in a dose-dependent and an enzymatic activity-dependent manner. Because it has been reported that Rgp activated protease-activated receptors (PARs), we examined whether the induction of HGF triggered by Rgps on human gingival fibroblasts occurred through PARs. An RNA interference assay targeted to PAR-1 and PAR-2 mRNA revealed that gingipains-induced secretion of HGF was significantly inhibited by RNA interference targeted to PAR-1 and PAR-2. In addition, the Rgps-mediated HGF induction was completely inhibited by the inhibition of phospholipase C and was clearly inhibited by RNA interference targeted to p65, which is an NF-kappaB component. These results suggest that Rgps activated human gingival fibroblasts to secrete HGF in the inflamed sites and the mechanism(s) involved may actively participate in both inflammatory and reparative processes in periodontal diseases.

Chicken egg yolk antibodies (IgY-technology): a review of progress in production and use in research and human and veterinary medicine

The production of antibodies (Abs) in chickens and the extraction of specific Abs from egg yolk (IgY Abs) are increasingly attracting the interest of the scientific community, as demonstrated by the significant growth of the IgY literature. This review offers detailed and comprehensive information about IgY-technology, including: a) possibilities for hen keeping in accordance with the Three Rs principles; b) new insights into the IgY transfer mechanism from blood to yolk as a biological basis for the technology; c) the comparative characteristics of IgY Abs and IgG Abs; d) the high efficacy of the technique, in view of the extraordinary amount of IgY Ab produced by one hen in one year (between 20 g and 40 g IgY in total); e) comparisons between the efficacies of IgY Abs and IgG Abs (rabbit, sheep, mouse) in several immunological assays; f) immunisation protocols, as well as the most commonly used IgY-extraction procedures; g) new possibilities for application in human and veterinary medicine, including strategies for the treatment of Helicobacter pylori infection or fatal intestinal diseases in children, particularly in poor countries, for reducing the use of antibiotics, and, in Asia and South America, for producing Abs against snake, spider and scorpion venoms; and h) the use of IgY Abs in various fields of research, also taking into consideration recent developments in South America (particularly Argentina and Cuba) and in Asia.

Hepatocyte growth factor (HGF) in patients with hepatitis B and meningitis

OBJECTIVES

The present study investigates serum hepatocyte growth factor (HGF) levels in patients with acute and chronic hepatitis B and the relation between these levels and intrahepatic inflammatory markers of the liver and fibrosis, as well as the cerebrospinal fluid (CSF) HGF levels in patients with meningitis and the relation between these levels and CSF findings. To our knowledge this is the first study regarding CSF HGF levels in tuberculous meningitis.

PATIENTS AND METHODS

The study consisted of 35 patients with chronic hepatitis B (HbeAg and HBV-DNA positive), 20 with acute hepatitis B, 20 with acute bacterial meningitis and 15 having tuberculous meningitis. HGF levels in the serum and CSF samples were measured by using the ELISA method.

RESULTS

The mean serum HGF levels in acute hepatitis B group were found statistically significantly higher than those in the control group and chronic hepatitis B group (p<0.0001). It was established that serum HGF levels in patients with chronic hepatitis B were significantly correlated with serum alanine aminotransferase (ALT) and HBV-DNA levels (r: 0.816, 0.951; p<0.05, respectively). Similarly, serum HGF levels of patients with chronic hepatitis B were correlated with fibrosis score and hepatic activity index of the liver histopathology (r: 0.750, 0.459; p<0.05, respectively). The mean CSF HGF levels of patients with acute bacterial meningitis and tuberculous meningitis were higher than those in the control group (p<0.05). In addition, it was observed that mean CSF HGF levels in patients suffered from tuberculous meningitis were statistically significantly higher than those in acute bacterial meningitis (p<0.05).

CONCLUSIONS

We suggest that serum HGF level in patients with chronic hepatitis B might reflect viral load, necro-inflammatory activity in the liver and the degree of structural progression. Our findings have demonstrated that tuberculous meningitis cause increased HGF concentrations in CSF. It is, therefore, suggested that examination of HGF levels in CSF may provide additional information in the differential diagnosis.

Hepatocyte growth factor/scatter factor in development, inflammation and carcinogenesis: its expression and role in oral tissues

Hepatocyte growth factor (HGF) was discovered as a potent mitogen for adult hepatocytes from the plasma of patients with fulminant hepatic failure. It is now known to be a broad-spectrum, multi-functional mitogen, motogen and morphogen. The activities of HGF are mediated through the signalling pathway of its receptor, c-Met. During tooth development, HGF is expressed in the dental papilla and c-Met is expressed in the inner enamel epithelium. The expression of HGF and c-Met indicates that HGF is involved in morphogenesis of the tooth by mediating epithelial-mesenchymal interactions. In the mature tooth, HGF expression by fibroblasts is enhanced in pulpitis and mediated through the induction of prostaglandin (PG) E(2); it is induced not only by inflammatory cytokines, but also by components of oral bacteria. Consequently, concentrations of HGF in gingival crevicular fluid (GCF) increase in periodontitis. The mitogenic and other biological activities, such as angiogenesis, of HGF contribute towards wound healing. Both HGF and c-Met are expressed in the developing tongue, and the signalling pathway of the latter is shown to be essential for myogenesis. Dysregulation of c-Met signalling is observed in carcinogenesis, but HGF also has cytotoxic activity to certain tumour cells. The reason for the discrepancy between these observations is not clear at present.

Increased hepatocyte growth factor level in cerebrospinal fluid in Alzheimer's disease

BACKGROUND & OBJECTIVE

Hepatocyte growth factor (HGF), also known as the scatter factor, is a potent mitogen for mature hepatocytes, and also has multifunctional effects on some cells in various organs. Recently, we have found expression and localization of HGF in white matter astrocytes in human brain tissues. Furthermore, immunohistochemistry using anti-HGF antibody revealed more intense immunolabeling in Alzheimer's disease (AD) than control brains. The aim of the study is to investigate the level of HGF in cerebrospinal fluid (CSF) from patients with AD.

MATERIAL AND METHODS

We examined the level of HGF in CSF from 34 AD and 15 age-matched disease control patients by highly sensitive enzyme-linked immunoabsorbent assay (ELISA) system.

RESULTS

Consistent with the immunohistochemical data, a significantly higher concentration of HGF in AD CSF was found as compared with controls. A significant correlation was also seen between CSF HGF levels and white matter high-signal foci determined on brain magnetic resonance imaging (MRI) in AD patients.

CONCLUSION

These results indicate that CSF HGF levels correspond with the white matter damage in AD brain.

Hepatocyte growth factor: from diagnosis to clinical applications

Hepatocyte growth factor (HGF), initially identified and molecularly cloned as a potent mitogen of primary cultured hepatocytes, has multiple activities in a variety of tissues during the course of development and also in various disease states. HGF plays key roles in the attenuation of disease progression as an intrinsic repair factor. It is also evident that HGF levels are regulated under different conditions, for example, during the course of pregnancy, aging, and disease. This review focuses on the levels of HGF in normal and pathophysiological situations and examines the relationships between HGF levels and disease, disease stage, and disease prognosis. The clinical potential of HGF as a treatment for subjects with various diseases is also given attention.

Hepatocyte growth factor in gingival crevicular fluid and the distribution of hepatocyte growth factor-activator in gingival tissue from adult periodontitis

Hepatocyte growth factor (HGF), also known as scatter factor, is a broad-spectrum and multifunctional cytokine required for the development, growth and regeneration of various organs and tissues. The expression of HGF in human gingival fibroblasts is induced by inflammatory cytokines such as interleukin 1. Thus, although it is possible that content of HGF in gingival crevicular fluid (GCF) in periodontitis is increased, this has not so far been reported because the volume of GCF is too small to determine HGF by the available enzyme-linked immunosorbent assay (ELISA). A recently developed, highly sensitive ELISA for HGF, with a detection limit of 1 pg/ml sample, has now enabled HGF to be measured in GCF.The mean HGF content in GCF from sites with clinically healthy gingiva, defined by the absence of overt signs of gingival inflammation and a probing depth (PD) <3 mm, was 1.7 ng/ml, and that of periodontitis, defined by obvious alveolar bone loss detected by radiographic examination and a PD> or =3 mm, was 3.23 ng/ml. Although treating the periodontitis did not significantly decrease the HGF concentration despite significantly improved clinical scores such as PD and Gingival Index, the total amount of HGF in GCF did decrease significantly after treatment. HGF was expressed by gingival fibroblasts and inflammatory cells as determined by in situ hybridization. HGF-activator (HGFA), which converts inactive pro-HGF to active mature HGF, was detected in gingival epithelial cells by immunostaining. The expression of HGFA was also confirmed in gingival tissue by reverse transcription-polymerase chain reaction (RT-PCR). These findings indicate that HGF is synthesized and activated in gingiva that is clinically healthy or associated with periodontitis.

Hepatocyte growth factor in cerebrospinal fluid in neurologic disease

OBJECTIVE

To investigate hepatocyte growth factor (HGF) concentration in cerebrospinal fluid (CSF) in neurologic disease.

MATERIALS AND METHODS

We determined CSF concentration of HGF with human-HGF-specific enzyme-linked immunosorbent assays (ELISA) in 121 patients: Alzheimer's disease (AD) (33), amyotrophic lateral sclerosis (ALS) (10), Parkinson's disease (PD) (5), progressive supranuclear palsy (PSP) (3), spinocerebellar degeneration (7), acute disseminating encephalomyelitis (ADEM) (6), human T-lymphotropic virus-1 (HTLV-1)-associated myelopathy (HAM) (6), multiple sclerosis (MS) (7), aseptic meningitis (AM) (12), and peripheral neuropathy and myopathy as control diseases (32).

RESULTS

HGF concentrations in CSF were significantly higher with diseases of the central nervous system (CNS) than control diseases and were slightly higher with AD than other neurodegenerative diseases. Values were highest with ADEM but decreased during corticosteroid treatment. We found no relationship between HGF in CSF and CSF cells or protein, immunoglobulin index, or Q albumin.

CONCLUSION

It is suggested that high concentrations of HGF in CSF may be partially related to CNS pathology, especially to demyelinating disease.

Circulating hepatocyte growth factor as a diagnostic marker of thrombus formation in patients with cerebral infarction

Circulating levels of hepatocyte growth factor (HGF) are increased in the early stage of an acute myocardial infarction because of arterial thrombosis. The purpose of this study was to use a new sensitive enzyme-linked immunosorbent assay to investigate whether circulating HGF is increased in patients with cerebral infarction. Circulating HGF was measured in 32 patients with cerebral infarction on admission to hospital and on days 2, 3, 7 and 14 after the onset of symptoms. Serum HGF levels exceeded the mean value +2SD (329pg/ml) measured in controls in 10 of 20 patients (50%) within 6 h after onset and in 15 of 32 patients (47%) within 24 h. Plasma D-dimer was increased in more than half of the patients with elevated HGF values. HGF levels in 16 patients who were measured serially were persistently increased throughout the study period. The results suggests that circulating HGF is a reliable early marker of cerebral infarction, and that this new sensitive HGF assay may be useful for diagnosing cerebral thrombosis.

International Standards for hepatocyte growth factor/scatter factor: initial assessment of candidate materials and their evaluation by multicentre collaborative study

Hepatocyte growth factor/scatter factor (HGF/SF) is a potent paracrine growth factor with motogenic, mitogenic and morphogenic activities, and a potential therapeutic role in hepatic and renal disease, as well as diagnostic and prognostic applications. It is synthesised as an inactive, single-chain precursor that is cleaved by serine proteases to give a biologically active, heterodimeric form. To develop World Health Organization (WHO) International Standards (IS) for HGF/SF, candidate preparations of the two forms were assessed in a multicentre study in which they were compared with local standards by bioassay and immunoassay. Among laboratories, there was a wide variation in the estimates of potencies of the candidate standards in terms of in-house reference preparations, but between-assay and within-assay variabilities were low within laboratories. In some assay systems, the precursor and heterodimer showed different responses. Since both molecular forms are widely used in current assay systems, this suggested that a reference preparation was required for each form of the HGF/SF molecule. Accordingly, the Expert Committee on Biological Standardization of WHO established the heterodimeric material (96/564) as the first IS for HGF/SF, human, recombinant, with an assigned unitage of 4000 IU/ampoule and, for the purpose of immunoassay calibration, a nominal HGF/SF content of 4 microg/ampoule. The precursor preparation (96/556) was established as the first IS for HGF/SF (precursor) with an assigned unitage of 2000 IU/ampoule and, for the purpose of immunoassay calibration, a nominal HGF/SF (precursor) content of 4 microg/ampoule. The preparations can be obtained upon written request to the National Institute for Biological Standards and Control (NIBSC, PO Box 1193), by e-mail (standards@nibsc.ac.uk) or ordered at http://www.nibsc.ac.uk.