Kallikrein-related peptidase 5 contributes to the remodeling and repair of bronchial epithelium

Inflammation, oxidative stress, and protease/protease inhibitor imbalance with excessive production of proteases are factors associated with pathogenesis of the chronic obstructive pulmonary disease (COPD). In this study, we report that kallikrein-related peptidase 5 (KLK5) is a crucial protease involved in extracellular matrix (ECM) remodeling and bronchial epithelial repair after injury. First, we showed that KLK5 degrades the basal layer formed by culture of primary bronchial epithelial cells from COPD or non-COPD patients. Also, exogenous KLK5 acted differently on BEAS-2B cells already engaged in epithelial-to-mesenchymal transition (EMT) or on 16HBE 14o- cells harboring epithelial characteristics. Indeed, by inducing EMT, KLK5 reduced BEAS-2B cell adherence to the ECM. This effect, neutralized by tissue factor pathway inhibitor 2, a kunitz-type serine protease inhibitor, was due to a direct proteolytic activity of KLK5 on E-cadherin, β-catenin, fibronectin, and α5β1 integrin. Thus, KLK5 may strengthen EMT mechanisms and promote the migration of cells by activating the mitogen-activated protein kinase signaling pathway required for this function. In contrast, knockdown of endogenous KLK5 in 16HBE14o- cells, accelerated wound healing repair after injury, and exogenous KLK5 addition delayed the closure repair. These data suggest that among proteases, KLK5 could play a critical role in airway remodeling events associated with COPD during exposure of the pulmonary epithelium to inhaled irritants or smoking and the inflammation process.

Tissue factor pathway inhibitor 2 is a potent kallikrein-related protease 12 inhibitor

The protease activities are tightly regulated by inhibitors and dysregulation contribute to pathological processes such as cancer and inflammatory disorders. Tissue factor pathway inhibitor 2 (TFPI-2) is a serine proteases inhibitor, that mainly inhibits plasmin. This protease activated matrix metalloproteases (MMPs) and degraded extracellular matrix. Other serine proteases are implicated in these mechanisms like kallikreins (KLKs). In this study, we identified for the first time that TFPI-2 is a potent inhibitor of KLK5 and 12. Computer modeling showed that the first Kunitz domain of TFPI-2 could interact with residues of KLK12 near the catalytic triad. Furthermore, like plasmin, KLK12 was able to activate proMMP-1 and -3, with no effect on proMMP-9. Thus, the inhibition of KLK12 by TFPI-2 greatly reduced the cascade activation of these MMPs and the cleavage of cysteine-rich 61, a matrix signaling protein. Moreover, when TFPI-2 bound to extracellular matrix, its classical localisation, the KLK12 inhibition was retained. Finally, TFPI-2 was downregulated in human non-small-cell lung tumour tissue as compared with non-affected lung tissue. These data suggest that TFPI-2 is a potent inhibitor of KLK12 and could regulate matrix remodeling and cancer progression mediated by KLK12.

Kallikrein-related peptidases in lung diseases

Human tissue kallikreins (KLKs) are 15 members of the serine protease family and are present in various healthy human tissues including airway tissues. Multiple studies have revealed their crucial role in the pathophysiology of a number of chronic, infectious and tumour lung diseases. KLK1, 3 and 14 are involved in asthma pathogenesis, and KLK1 could be also associated with the exacerbation of this inflammatory disease caused by rhinovirus. KLK5 was demonstrated as an influenza virus activating protease in humans, and KLK1 and 12 could also be involved in the activation and spread of these viruses. KLKs are associated with lung cancer, with up- or downregulation of expression depending on the KLK, cancer subtype, stage of tumour and also the microenvironment. Functional studies showed that KLK12 is a potent pro-angiogenic factor. Moreover, KLK6 promotes malignant-cell proliferation and KLK13 invasiveness. In contrast, KLK8 and KLK10 reduce proliferation and invasion of malignant cells. Considering the involvement of KLKs in various physiological and pathological processes, KLKs appear to be potential biomarkers and therapeutic targets for lung diseases.

Human kallikrein-related peptidase 12 stimulates endothelial cell migration by remodeling the fibronectin matrix

Kallikrein-related peptidase 12 (KLK12) is a kallikrein family peptidase involved in angiogenesis - a complex biological process in which the sprouting, migration and stabilization of endothelial cells requires extracellular matrix remodeling. To characterize the molecular mechanisms associated with KLK12's proangiogenic activity, we evaluated its ability to hydrolyze various matrix proteins. Our results show that KLK12 efficiently cleaved the human extracellular matrix proteins fibronectin and tenascin, both of which are involved in the regulation of endothelial cell adhesion and migration. For fibronectin, the major proteolytic product generated by KLK12 was a 29 kDa fragment containing the amino-terminal domain and the first five type I fibronectin-domains, which are essential for regulating fibronectin assembly. We also demonstrated that KLK12-mediated fibronectin proteolysis antagonizes fibronectin polymerization and fibronectin fibril formation by endothelial cells, leading to an increase in cell migration. Furthermore, a polyclonal antibody raised against KLK12's proteolytic cleavage site on fibronectin prevented the KLK12-dependent inhibition of fibronectin polymerization and the KLK12-mediated pro-migratory effect on endothelial cells. Taken as a whole, our results indicate that KLK12's proangiogenic effect is mediated through several molecular mechanisms.

Growth and survival of lung cancer cells: regulation by kallikrein-related peptidase 6 via activation of proteinase-activated receptor 2 and the epidermal growth factor receptor

The dysregulated expression of kallikrein-related peptidase 6 (KLK6) is involved in non-small cancer (NSCLC) cell growth. However, the mechanism that sustains KLK6 signaling remains unknown. We used an isogenic non-small cell lung cancer (NSCLC) cell model system to demonstrate that KLK6 promotes the proliferation of lung tumoral cells and restrains their apoptosis in vitro via ligand-dependent EGFR transactivation. KLK6 activated the ERK and Akt pathways and triggered the nuclear translocation of β-catenin. The stimulating effects of KLK6 required its proteolytic activity and were dependent on the protease-activated receptor 2 (PAR2). These observations support the concept of a role for KLK6 in the oncogenesis of NSCLC.

Angiogenesis stimulated by human kallikrein-related peptidase 12 acting via a platelet-derived growth factor B-dependent paracrine pathway

KLK12, a kallikrein peptidase, is thought to take part in the control of angiogenesis. Our analysis of the secretome of endothelial cells (ECs) that had been treated with KLK12 showed that KLK12 converts the extracellular matrix- or membrane-bound precursor of platelet-derived growth factor B (PDGF-B) into a soluble form. Both PDGF-B and vascular endothelial growth factor A (VEGF-A) take part in the induction of angiogenesis by KLK12 in a coculture model of angiogenesis that mimics endothelial tubule formation. We used a cellular approach to analyze the interplay between KLK12, PDGF-B, and VEGF-A and showed that release of PDGF-B by KLK12 leads to the fibroblast-mediated secretion of VEGF-A. This then stimulates EC differentiation and the formation of capillary tube-like structures. Thus, KLK12 favors the interaction of ECs and stromal cells. The released PDGF-B acts as a paracrine factor that modulates VEGF-A secretion by stromal cells, which ultimately leads to angiogenesis. Moreover, the genes encoding KLK12 and PDGFB are both expressed in ECs and up-regulated in tumor cells kept under hypoxic conditions, which is consistent with the physiological involvement of KLK12 in PDGF-B maturation.

Beneficial role of overexpression of TFPI-2 on tumour progression in human small cell lung cancer

Tissue factor pathway inhibitor-2 (TFPI-2) is a potent inhibitor of plasmin, a protease which is involved in tumour progression by activating (MMPs). This therefore makes TFPI-2 a potential inhibitor of invasiveness and the development of metastases. In this study, low levels of TFPI-2 expression were found in 65% of patients with small cell lung cancer (SCLC), the most aggressive type of lung cancer. To study the impact of TFPI-2 in tumour progression, TFPI-2 was overexpressed in NCI-H209 SCLC cells which were orthotopically implanted in nude mice. Investigations showed that TFPI-2 inhibited lung tumour growth. Such inhibition could be explained in vitro by a decrease in tumour cell viability, blockade of G1/S phase cell cycle transition and an increase in apoptosis shown in NCI-H209 cells expressing TFPI-2. We also demonstrated that TFPI-2 upregulation in NCI-H209 cells decreased MMP expression, particularly by downregulating MMP-1 and MMP-3. Moreover, TFPI-2 inhibited phosphorylation of the MAPK signalling pathway proteins involved in the induction of MMP transcripts, among which MMP-1 was predominant in SCLC tissues and was inversely expressed with TFPI-2 in 35% of cases. These results suggest that downregulation of TFPI-2 expression could favour the development of SCLC.

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The Tissue Factor Pathway Inhibitor-2 inhibits small cell lung cancer growth

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Monitoring of small cell lung cancer growth in a mouse orthotopic model by imaging

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Increasing information on the role of TFPI-2 in human lung tumour cells

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Increasing information on TFPI-2 and protease expression in human tissue samples

TFPI-2 silencing increases tumour progression and promotes metalloproteinase 1 and 3 induction through tumour-stromal cell interactions

Tissue factor pathway inhibitor-2 (TFPI-2) is a potent inhibitor of plasmin which activates matrix metalloproteinases (MMPs) involved in degradation of the extracellular matrix. Its secretion in the tumour microenvironment makes TFPI-2 a potential inhibitor of tumour invasion and metastasis. As demonstrated in aggressive cancers, TFPI-2 is frequently down-regulated in cancer cells, but the mechanisms involved in the inhibition of tumour progression remained unclear. We showed in this study that stable TFPI-2 down-regulation in the National Cancer Institute (NCI)-H460 non-small cell lung cancer cell line using specific micro interfering micro-interfering RNA promoted tumour progression in a nude mice orthotopic model that resulted in an increase in cell invasion. Moreover, TFPI-2 down-regulation enhanced cell adhesion to collagen IV and laminin via an increase in α₁ integrin on cell surface, and increased MMP expression (mainly MMP-1 and -3) contributing to cancer cell invasion through basement membrane components. This study also reveals for the first time that pulmonary fibroblasts incubated with conditioned media from TFPI-2 silencing cancer cells exhibited increased expression of MMPs, particularly MMP-1, -3 and -7, that are likely involved in lung cancer cell invasion through the surrounding stromal tissue, thus enhancing formation of metastases.

Monitoring of tumour progression using bioluminescence imaging and computed tomography scanning in a nude mouse orthotopic model of human small cell lung cancer

Human small cell lung carcinoma (SCLC) is the most aggressive type of lung cancer but no clinically relevant animal model has been developed to date. Such a model would be valuable to study the molecular aspects of tumour progression and to test the effectiveness of new treatment agents. We generated a reproducible and reliable nude mouse orthotopic model of human SCLC with NCI-H209 tumour cells genetically modified to express firefly luciferase. Cells were analysed for long-term stability of bioluminescence and a clone was passaged twice subcutaneously to enhance tumorigenicity. Cells resuspended in Matrigel and/or EDTA RPMI medium containing a (99m)Tc-labelled tin colloid used as tracer were implanted intrabronchially with a catheter inserted into the trachea and positioned in the main bronchus using X-ray-guided imaging. Deposition of cells into the lung was then assessed by scintigraphy. The growth of the primary tumour was sensitively and non-invasively followed by bioluminescence imaging that allowed real-time monitoring of tumour progression in the same animals over a 2-12-week period. Additional 3D bioluminescence imaging and computed tomography scanning were used to document tumour location and measurements that were confirmed by histological analyses. In conclusion, this original nude mouse orthotopic model resembles various stages of human small cell lung cancer, and therefore could be used to evaluate new treatment strategies.

Inhibition of cervical cancer cell growth by human papillomavirus virus-like particles packaged with human papillomavirus oncoprotein short hairpin RNAs

Overexpression of human papillomavirus (HPV E6 and HPV E7) oncogenes in human cervical cells results in the development of cancer, and E6 and E7 proteins are therefore targets for preventing cervical cancer progression. Here, we describe the silencing of E6 and E7 expression in cervical carcinoma cells by RNA interference. In order to increase the efficacy of the RNA interference, HPV pseudovirions coding for a short hairpin RNA (shRNA) sequence were produced. The results indicated the degradation of E6 and E7 mRNAs when shRNA against E6 or E7 were delivered by pseudovirions in HPV-positive cells (CaSki and TC1 cells). E6 silencing resulted in the accumulation of cellular p53 and reduced cell viability. More significant cell death was observed when E7 expression was suppressed. Silencing E6 and E7 and the consequences for cancer cell growth were also investigated in vivo in mice using the capacity of murine TC1 cells expressing HPV-16 E6 and E7 oncogenes to induce fast-growing tumors. Treatment with lentiviruses and HPV virus-like particle vectors coding for an E7 shRNA sequence both resulted in dramatic inhibition of tumor growth. These results show the ability of pseudovirion-delivered shRNA to produce specific gene suppression and provide an effective means of reducing HPV-positive tumor growth.

Influence of MMP-2 and MMP-9 promoter polymorphisms on gene expression and clinical outcome of non-small cell lung cancer

Matrix metalloproteinases (MMP) including MMP-2 and MMP-9 play a major role in tumour invasion by proteolysing the extracellular matrix. Their activation, particularly that of MMP-9, is partly dependent on plasmin that is inhibited by TFPI-2 (tissue factor pathway inhibitor-2), a serine protease inhibitor whose gene expression is decreased in about one-third of non-small cell lung cancers (NSCLC). In addition, MMP-2 and MMP-9 are essential in the development of NSCLC and can be regulated by functional promoter polymorphisms. In this study, the -1306C/T MMP-2, -735C/T MMP-2 and -1562C/T MMP-9 polymorphisms were analysed in 90 NSCLC patients and 90 controls. In addition, the promoter region of the TFPI-2 gene was screened for sequence variations in both groups by DHPLC. A -167G/A polymorphism was identified in 3% of controls whereas none of the 90 patients exhibited this genetic variation in the TFPI-2 promoter region. Moreover, no difference in -1306C/T MMP-2, -735C/T MMP-2 and -1562C/T MMP-9 genotypes was found between cases and controls. However, the homozygous -1562CC MMP-9 genotype was more frequent in patients with squamous cell carcinoma than in controls (p=0.018). When genotype distributions were compared to MMP-2 and MMP-9 gene expression in tumours, no relationship was found with the -1306 MMP-2 and -1562 MMP-9 polymorphisms. In contrast, tumour MMP-2 gene expression was lower in homozygous -735CC patients than in those with CT or TT genotypes. In addition, the survival time was longer in patients with the MMP-2 -735T allele than in those with the CC genotype (p=0.02). The relative risk of death was increased 2.6-fold in -735CC patients (p=0.045; 95% CI=1.0-6.7). The results of this study suggest that the -735C/T MMP-2 polymorphism might be an independent prognostic marker in NSCLC, but this should be confirmed in a larger cohort of patients.

Voltage-gated sodium channels potentiate the invasive capacities of human non-small-cell lung cancer cell lines

Ionic channel activity is involved in fundamental cellular behaviour and participates in cancerous features such as proliferation, migration and invasion which in turn contribute to the metastatic process. In this study, we investigated the expression and role of voltage-gated sodium channels in non-small-cell lung cancer cell lines. Functional voltage-gated sodium channels expression was investigated in normal and non-small-cell lung cancer cell lines. The measurement, in patch-clamp conditions, of tetrodotoxin-inhibitable sodium currents indicated that the strongly metastatic cancerous cell lines H23, H460 and Calu-1 possess functional sodium channels while normal and weakly metastatic cell lines do not. While all the cell lines expressed mRNA for numerous sodium channel isoforms, only H23, H460 and Calu-1 cells had a 250 kDa protein corresponding to the functional channel. The other cell lines also had another protein of 230 kDa which is not addressed to the membrane and might act as a dominant negative isoform to prevent channel activation. At the membrane potential of these cells, channels are partially open. This leads to a continuous entry of sodium, disrupting sodium homeostasis and down-stream signaling pathways. Inhibition of the channels by tetrodotoxin was responsible for a 40-50% reduction of in vitro invasion. These experiments suggest that the functional expression of voltage-gated sodium channels might be an integral component of the metastatic process in non-small-cell lung cancer cells probably through its involvement in the regulation of intracellular sodium homeostasis. These channels could serve both as novel markers of the metastatic phenotype and as potential new therapeutic targets.

CCL5-enhanced human immature dendritic cell migration through the basement membrane in vitro depends on matrix metalloproteinase-9

The proinflammatory chemokine CC chemokine ligand 5 (CCL5) is a potent chemoattractant of immature dendritic cells (iDCs). It remains to be elucidated whether CCL5 may also enhance iDC migration through the basement membrane by affecting matrix metalloproteinase (MMP)-9 secretion. In this study, iDCs were differentiated in vitro from human monocytes of healthy donors. Zymographic analysis of cellular membranes of nontreated iDCs revealed a basal secretion of the pro- and active MMP-9, whereas only pro-MMP-9 was detected in conditioned media. Increasing concentrations of CCL5 significantly enhanced MMP-9 secretion by iDCs, peaking at 100 ng/ml, which optimally increased iDC migration through a reconstituted basement membrane (Matrigel) in vitro. The CCL5-enhanced secretion of MMP-9 occurred early (2 h) and was maintained at least for 10 h. A significant increase in MMP-9 mRNA synthesis was detected by reverse transcriptase-polymerase chain reaction, only at 6 h of CCL5 treatment, which suggests that the early effect of CCL5 (0-4 h) on MMP-9 secretion was independent of mRNA synthesis, whereas the more delayed effect (6-10 h) could be mediated through an increase in MMP-9 gene expression. In a Matrigel migration assay, the CCL5-enhanced iDC migration was reduced significantly by specific inhibitors of MMP-9, such as tissue inhibitor of metalloproteinase-1 or an anti-MMP-9 antibody, which indicates that iDC migration through the basement membrane depends on MMP-9. These results suggest that under inflammatory conditions, the chemokine CCL5 may enhance iDC migration through the basement membrane by rapidly increasing their MMP-9 secretion.

CCL5-enhanced human immature dendritic cell migration through the basement membrane in vitro depends on matrix metalloproteinase-9

The proinflammatory chemokine CC chemokine ligand 5 (CCL5) is a potent chemoattractant of immature dendritic cells (iDCs). It remains to be elucidated whether CCL5 may also enhance iDC migration through the basement membrane by affecting matrix metalloproteinase (MMP)-9 secretion. In this study, iDCs were differentiated in vitro from human monocytes of healthy donors. Zymographic analysis of cellular membranes of nontreated iDCs revealed a basal secretion of the pro- and active MMP-9, whereas only pro-MMP-9 was detected in conditioned media. Increasing concentrations of CCL5 significantly enhanced MMP-9 secretion by iDCs, peaking at 100 ng/ml, which optimally increased iDC migration through a reconstituted basement membrane (Matrigel) in vitro. The CCL5-enhanced secretion of MMP-9 occurred early (2 h) and was maintained at least for 10 h. A significant increase in MMP-9 mRNA synthesis was detected by reverse transcriptase-polymerase chain reaction, only at 6 h of CCL5 treatment, which suggests that the early effect of CCL5 (0-4 h) on MMP-9 secretion was independent of mRNA synthesis, whereas the more delayed effect (6-10 h) could be mediated through an increase in MMP-9 gene expression. In a Matrigel migration assay, the CCL5-enhanced iDC migration was reduced significantly by specific inhibitors of MMP-9, such as tissue inhibitor of metalloproteinase-1 or an anti-MMP-9 antibody, which indicates that iDC migration through the basement membrane depends on MMP-9. These results suggest that under inflammatory conditions, the chemokine CCL5 may enhance iDC migration through the basement membrane by rapidly increasing their MMP-9 secretion.

Improved PCR method for amplification of GC-rich DNA sequences

Most housekeeping genes, tumor-suppressor genes, and approx 40% of tissue-specific genes contain G+C sequences in their promoter region that were very difficult to amplify. In this report, we propose an improved polymerase chain reaction (PCR) method to be used for successful amplification of the tissue factor pathway inhibitor (TFPI)-2 gene promoter region that exhibit >70% G+C content in a sequence of approx 300 bp and a complete CpG island region spanning exon 1, the three transcription initiation sites, and the translation start site. Therefore, this method can be recommended to amplify other GC-rich genomic templates.

Expression and methylation status of tissue factor pathway inhibitor-2 gene in non-small-cell lung cancer

Tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type serine proteinase inhibitor that inhibits plasmin-dependent activation of several metalloproteinases. Downregulation of TFPI-2 could thus enhance the invasive potential of neoplastic cells in several cancers, including lung cancer. In this study, TFPI-2 mRNA was measured using a real-time PCR method in tumours of 59 patients with non-small-cell lung cancer (NSCLC). Tumour TFPI-2 mRNA levels appeared well correlated with protein expression evaluated by immunohistochemistry and were 4-120 times lower compared to those of nonaffected lung tissue in 22 cases (37%). Hypermethylation of the TFPI-2 gene promoter was demonstrated by restriction enzyme-polymerase chain reaction in 12 of 40 cases of NSCLC (30%), including nine of 17 for whom tumour TFPI-2 gene expression was lower than in noncancerous tissue. In contrast, this epigenetic modification was shown in only three of 23 tumours in which no decrease in TFPI-2 synthesis was found (P=0.016). Decreased TFPI-2 gene expression and hypermethylation were more frequently associated with stages III or IV NSCLC (eight out of 10, P=0.02) and the TFPI-2 gene promoter was more frequently hypermethylated in patients with lymph node metastases (eight out of 16, P=0.02). These results suggest that silencing of the TFPI-2 gene by hypermethylation might contribute to tumour progression in NSCLC.

Human choriocarcinoma cell resistance to natural killer lysis due to defective triggering of natural killer cells

The trophoblast, the outermost layer of the human placenta, lacks expression of the classical human leukocyte antigen (HLA) class I molecules. This prevents allorecognition by T cells but raises the question of what protects the trophoblast from natural killer (NK) cells. In a previous study, we have shown that choriocarcinoma cell (CC) resistance to NK lysis was mainly independent of HLA class I molecules. In the present study, we postulated that CC may prevent activation of NK cells by failing to stimulate their triggering receptors (TR). To test this hypothesis, we evaluated the lysis of JAR and JEG-3 CC after effective cross-linking and activation of NK cells by means of lectins or antibodies. Our results show that NK-resistant CC were sensitive to lysis by unstimulated peripheral blood lymphocytes in the presence of phytohemagglutin (PHA), to antibody-dependent cell cytotoxicity in presence of anti-Tja antibodies, and to monoclonal antibody redirected killing using anti-TR antibodies anti-CD16 and anti-CD244/2B4. Finally, CC fail to express CD48, the ligand for CD244/2B4. These results indicate that the resistance of CC to lysis results primarily from defective NK cell activation, at least partially due to the lack of expression of ligands, such as CD48, involved in the triggering of NK cells.

Transcriptional silencing of the TFPI-2 gene by promoter hypermethylation in choriocarcinoma cells

Tissue factor pathway inhibitor-2 (TFPI-2), a Kunitz-type serine proteinase inhibitor associated with the extracellular matrix, has been shown to reduce tumor invasion. In the present study we identified the presence of a complete CpG island region spanning exon 1 and the three transcription initiation sites. We demonstrate that DNA demethylation by 5'-aza-2'-deoxycytidine restores TFPI-2 transcription in JAR choriocarcinoma cells. The effect of in vitro DNA methylation on TFPI-2 promoter function was also confirmed with TFPI-2/luciferase promoter constructs. Finally, we determined the precise methylation status of CpG sites of the TFPI-2 promoter in normal and tumor trophoblast cells using the bisulfite genomic sequencing method. We conclude that hypermethylation of the TFPI-2 gene is correlated with transcriptional silencing and that the TFPI-2 gene may be a candidate tumor suppressor gene.

Demonstration of a tissue factor pathway inhibitor 2 messenger RNA synthesis by pure villous cytotrophoblast cells isolated from term human placentas

Tissue factor pathway inhibitor 2 (TFPI-2), a Kunitz-type proteinase inhibitor, might play an important role during placenta growth by regulating trophoblast invasion and differentiation. Many TFPI-2 transcripts have been detected in syncytiotrophoblast cells, but conflicting results have been reported concerning TFPI-2 synthesis by the cytotrophoblast. To address this issue, we developed a method to isolate pure preparations of human villous cytotrophoblast cells from normal term placentas, and the synthesis of tissue factor, TFPI-1, and TFPI-2 mRNAs was then evaluated. Cells were isolated by trypsin-DNase-EDTA digestion, followed by Percoll gradient separation and immunodepletion of human leukocyte antigen-positive cells. The quality of villous cytotrophoblast cells was verified by electron microscopy. Purity of cell preparations was assessed by labeling cells with GB25, a monoclonal antibody specific to villous trophoblast cells, and by checking the absence of contaminating cells using anti-CD9 antibody. The lack of hCG, CD32 mRNA, and tissue factor mRNA also indicated the absence of contaminating cells. Using competitive reverse transcription polymerase chain reaction, we showed that freshly isolated villous cytotrophoblast cells synthesized significant levels of TFPI-1 mRNA and larger amounts of TFPI-2 mRNA. TFPI-1 and TFPI-2 mRNA synthesis remained unchanged when cytotrophoblast cells were cultured in complete medium and evolved as a multinucleated syncytiotrophoblast. These results indicate that the villous cytotrophoblast and syncytiotrophoblast are both important sites of TFPI-2 synthesis in the human placenta. This study also indicates that tissue factor detection should be used systematically to check the purity of cytotrophoblast cell preparations because it allows detection of contamination by monocytes/macrophages and by syncytial fragments.

Characterization and functional analysis of TFPI-2 gene promoter in a human choriocarcinoma cell line

Tissue factor pathway Inhibitor-2 (TFPI-2) is associated with extracellular matrices and plays a major role in cell migration and tumor invasion. In this study, a 4.8-kb human TFPI-2 gene 5'-flanking region was isolated, cloned and sequenced. Promoter region analysis revealed a high GC-rich content without canonical TATA and CAAT boxes but three transcription initiation sites were identified. Moreover, several putative binding sites for transcription factors were identified (MyoD, LYF1, NF-Y, GATA, oct-1, AP-1, Sp1, NF1, NF-kappa B and egr-1). To characterize potential regulatory regions, TFPI-2/luciferase promoter constructs were then transfected in human choriocarcinoma JEG-3 cells. We first showed that the minimal TFPI-2 promoter is located between -166 and -111 from the translation start site. Luciferase activity consistently increased after stimulation of JEG-3 cells by phorbol 12-myristate 13-acetate indicating that NF1, NF-kappa B and egr-1/Sp1 binding sites are crucial in inducible TFPI-2 expression. Moreover, negative regulatory regions included AP-1 binding sites were identified. This study demonstrates that the TFPI-2 gene promoter exhibits typical features of a housekeeping gene.

FasL-transfected endothelial cells decrease the proliferative response of allogeneic PBL

Graft endothelium has a key role in organ transplantation because it regulates graft infiltration by allogeneic activated T cells. Overexpression of death molecules that could induce apoptosis of alloreactive T cells might be an alternative to the immunosuppressive treatment currently used in graft transplantation. Several studies have shown that immune-privileged sites express Fas ligand (FasL) and induce apoptosis of activated T-cells. We propose that endothelial cells engineered to express FasL could inhibit alloreactive T cell-proliferation by inducing apoptosis. An expression vector was constructed with human FasL cDNA and used to transfect an endothelial cell line (ECV304 cells). We demonstrated that FasL-transfected ECV304 cells were effective in inducing apoptosis of Jurkat T cell lymphoma as an agonist anti-Fas antibody. Using a mixed lymphocyte-endothelial cell culture model we observed that FasL-transfected ECV304 cells which conserved their two principal costimulatory pathways inhibited alloreactive T cell-proliferation by inducing activated T-cell apoptosis. These results suggest that endothelial cells could be interesting candidates to convey a death signal and induce hyporesponsiveness of alloreactive T cells during organ transplantation.

Phosphatidylinositol 3-kinases are involved in the all-trans retinoic acid-induced upregulation of CD38 antigen on human haematopoietic cells

All-trans retinoic acid (ATRA) is a specific inducer of CD38 antigen on marrow CD34+ cells as well as on blast cells in acute promyelocytic and myeloblastic leukaemia. The CD38 antigen contributes to the control of blast cell proliferation, and the upregulation of CD38 might constitute an element in the pathogenesis of retinoic acid syndrome. The aim of this study was to determine whether phosphoinositide 3-kinase (PI3-K) is involved in the modification of CD38 antigen expression on myeloid cells, as PI3-K plays a major role in the ATRA-induced granulocytic differentiation of HL-60 cells. We evaluated the effects of PI3-K inhibitors (wortmannin and LY294002) on the levels of CD38 antigen and mRNA in HL-60 and normal marrow CD34+ cells exposed to ATRA (1 micromol/l). The inhibitors prevented increase in CD38 mRNA expression and the overexpression of membrane CD38 antigen, without modification of the cytoplasmic level of this antigen. Interestingly, PI3-K activity was also necessary for CD38 expression on normal marrow CD34+ cells and for the ATRA-induced upregulation of CD157, a CD38-related antigen. In conclusion, PI3-K activity plays an essential role in the regulation of CD38 expression on human haematopoietic cells, and might constitute an interesting therapeutic target in haematological disorders involving CD38 overexpression.

Demonstration of inducible TFPI-2 mRNA synthesis in BeWo and JEG-3 trophoblast cells using a competitive RT-PCR

Tissue factor pathway inhibitor-2 (TFPI-2) displays structural similarities with TFPI-1, the major inhibitor of tissue factor (TF)/, factor VIIa. It is synthesized mostly by syncytiotrophoblast in the placenta, but its physiological functions are not fully understood. We studied the synthesis of TFPI-2 mRNA and that of TFPI-1 and TF in three human trophoblast cell lines, JAR, BeWo, and JEG-3. We first developed specific competitive reverse transcription-polymerase chain reaction (RT-PCR) assays for each gene studied using human umbilical vein endothelial cells (HUVEC). The three trophoblast cell lines strongly synthesized TF mRNA whereas the synthesis of TFPI-1 mRNA was very low. TFPI-2 mRNA was not detected in unstimulated or stimulated JAR cells. In contrast, JEG-3 and, to a lesser extent, BeWo produced significant amounts of TFPI-2 mRNA, which were significantly increased after stimulation with phorbol 12-myristate 13-acetate (PMA). However, tumor necrosis factor-alpha (TNF-alpha) had no effect on this synthesis. JEG-3 and BeWo are thus two cell lines that could be used to study TFPI-2 gene regulation and to investigate the role of TF, TFPI-1, and TFPI-2 during trophoblast differentiation.

Induction of monocyte tissue factor expression by antibodies to heparin-platelet factor 4 complexes developed in heparin-induced thrombocytopenia

The pathogenesis of thrombosis in heparin-induced thrombocytopenia (HIT) was studied by investigating whether antibodies to heparin-platelet factor 4 (H-PF4) induced tissue factor (TF) synthesis by monocytes. Plasma from 5 patients with HIT containing IgG to H-PF4 was incubated with peripheral blood mononuclear cells without or with purified PF4 and heparin. Significant TF-dependent procoagulant activity (PCA) expressed by monocytes, measured with a factor Xa-based chromogenic assay, was induced after incubation of each HIT plasma sample. This monocyte PCA required the presence of PF4 and was inhibited by high concentrations of heparin. Furthermore, purified HIT IgG added to whole blood with PF4 and heparin also provoked significant synthesis of TF mRNA by monocytes, demonstrated by RT-PCR, and this effect was not observed with normal IgG. These findings strongly support the hypothesis that antibodies to PF4 developed in HIT trigger the production of tissue factor by monocytes, and this effect could account in vivo for hypercoagulability and thrombotic complications in affected patients.

Nasal immunization of mice with Cryptosporidium parvum DNA induces systemic and intestinal immune responses

DNA immunization offers a novel approach to inducing humoral and cellular immunity against infectious pathogens. We examined whether such an approach could be used against cryptosporiodiosis, an intestinal disease caused by the protozoan parasite Cryptosporidium parvum. This infection is a major problem for young ruminants and immunosuppressed individuals in whom cryptosporidiosis causes life-threatening symptoms. The life cycle of C. parvum takes place in the enterocytes of the intestinal epithelium. We therefore focused our attention on a route of immunization that might induce a mucosal immunoglobulin (Ig)A response. Eight-week-old BALB/c mice were immunized intranasally with DNA encoding a 15-kDa C. parvum sporozoite antigen (CP15-DNA) cloned onto the plasmid pcDNA3. CP15-DNA-immunized mice developed specific and longlasting production of anti-CP15 Ig A in intestinal secretions and specific IgG in sera 3 months and 1 year after the first DNA inoculation. CP15-DNA-immunized mice also developed an antigen-specific T lymphocyte proliferative response in both spleen and mesenteric lymph nodes. Control mice that received the pcDNA3 plasmid alone did not develop specific humoral and cellular responses. These results indicate that plasmid DNA may provide a powerful means of eliciting intestinal humoral and cellular responses to C. parvum infections in mammals.

Comparison of the humoral and cellular immune responses to two preparations of Cryptosporidium parvum CP15/60 recombinant protein

This study compares the immune responses produced by immunising mice and rabbits with two preparations of the recombinant 15/60 kDa protein of Cryptosporidium parvum. Genomic C. parvum DNA was amplified and the recombinant protein was synthesized as a fusion protein with glutathione-S-transferase in Escherichia coli and in the eukaryotic system of baculovirus/insect cells. Both recombinant proteins induced similar levels of serum antibodies against the fusion recombinant protein, but the eukaryotic recombinant protein triggered a stronger humoral response to C. parvum. Similarly, increased lymphoproliferation occurred only after stimulation of spleen cells from mice immunised with the eukaryotic recombinant protein. This suggests that the eukaryotic protein is a better candidate for immunological studies on cryptosporidiosis.

Antibodies to platelet factor 4-heparin after cardiopulmonary bypass in patients anticoagulated with unfractionated heparin or a low-molecular-weight heparin : clinical implications for heparin-induced thrombocytopenia

BACKGROUND

Cardiopulmonary bypass (CPB) induces platelet activation with release of platelet factor 4 (PF4), and patients are exposed to high doses of heparin (H). We investigated whether this contributes to the development of antibodies to H-PF4 and heparin-induced thrombocytopenia (HIT).

METHODS AND RESULTS

CPB was performed with unfractionated heparin (UFH) in 328 patients. After surgery, patients received UFH (calcium heparin, 200 IU. kg-1. d-1) (group 1, n=157) or low-molecular-weight heparin (LMWH, Dalteparin, 5000 IU once daily) (group 2, n=171). Eight days after surgery, antibodies to H-PF4 were present in 83 patients (25.3%), 46 in group 1 and 37 in group 2 (P=0.12). Most patients (61%) had IgG1 to H-PF4, but only 8 samples with antibodies induced platelet activation with positive results on serotonin release assay. HIT occurred in 6 patients in group 1, but no thrombocytopenia was observed in subjects receiving LMWH, although 2 had high levels of antibodies with positive serotonin release assay results. When antibodies to H-PF4 were present, mean platelet counts were lower only in patients with FcgammaRIIA R/R131 platelets.

CONCLUSIONS

These results provide evidence that the development of antibodies to H-PF4 after CPB performed with UFH is not influenced by the postoperative heparin treatment. The antibodies associated with high risk of HIT are mainly IgG1, which is present at high titers in the plasma of patients continuously treated with UFH.

Protection of kids against Cryptosporidium parvum infection after immunization of dams with CP15-DNA

In this study the effectiveness of a DNA vaccine to confer protection against cryptosporidiosis, an enteric infection of lifestock and humans, was evaluated. A vaccination protocol using a recombinant plasmid encoding the 15 kDa surface sporozoite protein of Cryptosporidium parvum was developed in adult pregnant goats. The present study reports that nasal immunization of pregnant goats with CP15-DNA led to a transfer of immunity to offspring conferring protection against C. parvum infection. Kids from CP15-DNA-vaccinated dams shed significantly fewer oocysts and over a shorter period than did kids from unvaccinated goats. The low level of parasite development in protected kids did not affect their growth whereas unprotected kids grew much slowly. There was still a significant difference in the weights of protected and unprotected kids after complete recovery. Anti-CP15 antibodies were present in serum and colostrum from vaccinated goats. Nevertheless, the precise immune mechanism of protection has still to be determined. This vaccine should reduce the economic losses due to cryptosporidiosis in ruminants, specially in small ruminants (calves, lambs, kids). It has also the potential to reduce environmental contamination by reducing oocyst shedding.

Fast detection of tissue factor and tissue factor pathway inhibitor messenger RNA in endothelial cells and monocytes by sensitive reverse transcription-polymerase chain reaction

We developed fast and sensitive reverse transcription-polymerase chain reaction (RT-PCR) procedures to study the expression of tissue factor (TF) and tissue factor pathway inhibitor (TFPI-1) mRNA in human endothelial cells and monocytes. The sensitivity of the technique was checked by performing RT-PCR with limited numbers of cells. Cells were stimulated either with tumor necrosis factor (TNF-alpha) or endotoxin to induce TF mRNA expression or with phorbol ester to increase TFPI-1 mRNA expression. Thus, RT-PCR specific for TF mRNA provided detection from as few as 10(3) TNF-alpha stimulated endothelial cells and 5 x 10(2) monocytes stimulated by endotoxin. TF mRNA expression was increased by TNF-alpha in endothelial cells and in monocytes stimulated by endotoxin. Elevated expression of TF mRNA in monocytes without stimulation by endotoxin was mainly related to cell adhesion. TFPI-1 mRNA was constitutively expressed in endothelial cells and was detected in only 5 x 10(2) unstimulated cells and 10(2) phorbol ester-stimulated cells. Expression was increased upon stimulation with phorbol ester. With this technique, TFPI-1 mRNA in monocytes was rather low even when cells were stimulated with phorbol ester or after adhesion.

Human allogeneic lymphocytes trigger endothelial cell tissue factor expression by a tumor necrosis factor-dependent pathway

Lymphocyte adhesion to endothelial cells and the extravascular deposition of fibrin are 2 important processes during pathologic situations such as allograft rejection. Tissue factor (TF) expression was therefore measured on human umbilical vein endothelial cells (HUVECs) after coculture with allogeneic lymphocytes (PBLs) by a factor Xa generation assay. When cocultured with PBLs, HUVECs expressed strong procoagulant activity related to the TF/factor VII-dependent pathway, which was enhanced when endothelial cells were treated with interferon-gamma (IFN-gamma). The highest TF activity was measured when 10(5) lymphocytes were incubated with 10(4) HUVECs (ratio 10: 1) for 4 hours, a time-dependent course similar to that obtained with tumor necrosis factor-alpha (TNF-alpha), and direct contact between the 2 cell types was necessary. PBL-induced TF activity was inhibited by cycloheximide or actinomycin D, indicating active protein synthesis that was confirmed by the increase in TF mRNA detected by reverse transcription-polymerase chain reaction. It was then demonstrated that 1 of the primary signaling pathways leading to endothelial cell TF expression was a rapid initial interaction between membrane TNF expressed on PBLs and the 75-kd TNF receptor, with subsequent involvement of platelet-activating factor and P-selectin. Finally, we showed that the transduction of external signals involving the activation of protein kinase C and protein tyrosine kinases also contributed to the regulation of TF expression.

Pseudo-homozygous activated protein C resistance due to coinheritance of heterozygous factor V Leiden mutation and type I factor V deficiency. Variable expression when analyzed by different activated protein C resistance functional assays

The laboratory diagnosis of activated protein C (APC) resistance is based on a weak anticoagulant response to APC using a chronometric procedure confirmed in almost all cases by molecular diagnosis of the FV Leiden mutation. A recently-developed Xa-based assay (Accelerimat, Biomerieux) was compared with two different activated partial thromboplastin time (APTT)-based procedures (Coatest APC resistance and Modified Coatest, Chromogenix) in 115 patients with a personal or familial history of thrombotic disease, or both, being studied for the FV Leiden mutation. Our results confirmed the improvement in specificity for the FV Leiden mutation when the APTT-based assay was performed after dilution of samples in FV-deficient plasma (Modified Coatest). However, five patients who were heterozygous for the FV Leiden mutation appeared to be homozygous when tested by both APTT-based assays. These patients, belonging to three different families, had a FV type I deficiency with FV plasma levels between 43 and 64%. In contrast, the Xa-based method was not influenced by the decrease in plasma FV levels. Thus, this procedure is more specific than APTT-based assays to predict the genotype status of the FV Leiden mutation.

Major antigens of Cryptosporidium parvum recognised by serum antibodies from different infected animal species and man

Serum humoral immune response to Cryptosporidium parvum was evaluated in six species: mouse, rabbit, lamb, calf, pig and man. Electrophoretic and immunoblot analysis showed that specific animal antibody response appeared between Day 4 and Day 15 post inoculation. The two main target antigens had apparent molecular weights of 15-17 and 23 kDa. They were recognised by each species studied. Serum IgA intensively recognised the 15-17 kDa antigen, except in rabbit. This study demonstrates that these two antigens are consistent targets of humoral immune response and can therefore be of great interest in studies of therapy/prophylaxis.

Self-assembly of human papillomavirus type 16 capsids by expression of the L1 protein in insect cells

The L1 major protein of human papillomavirus type 16 was expressed in Sf-21 insect cells with a recombinant baculovirus vector. Virus-like particles similar in appearance to empty virions were identified by electron microscopy at densities of 1.29-1.30. Purified particles reacted with monoclonal anti-HPV-16-L1 antibody in Western blot and immuno dot blot suggesting that conformational epitopes are present in the recombinant particles. Immunodot blot assays using human sera correlated with the detection of HPV-16 DNA by the polymerase chain reaction. The results suggest that HPV-16-L1 virions produced by the baculovirus system might be useful for developing serologic tests to measure antibodies to conformational epitopes and may offer potential for vaccine development.