Normal human keratinocytes bind to the alpha3LG4/5 domain of unprocessed laminin-5 through the receptor syndecan-1

Basal keratinocytes of the epidermis adhere to their underlying basement membrane through a specific interaction with laminin-5, which is composed by the association of alpha3, beta3, and gamma2 chains. Laminin-5 has the ability to induce either stable cell adhesion or migration depending on specific processing of different parts of the molecule. One event results in the cleavage of the carboxyl-terminal globular domains 4 and 5 (LG4/5) of the alpha3 chain. In this study, we recombinantly expressed the human alpha3LG4/5 fragment in mammalian cells, and we show that this fragment induces adhesion of normal human keratinocytes and fibrosarcoma-derived HT1080 cells in a heparan- and chondroitin sulfate-dependent manner. Immunoprecipitation experiments with Na2 35SO4-labeled keratinocyte and HT1080 cell lysates as well as immunoblotting experiments revealed that the major proteoglycan receptor for the alpha3LG4/5 fragment is syndecan-1. Syndecan-4 from keratinocytes also bound to alpha3LG4/5. Furthermore we could show for the first time that unprocessed laminin-5 specifically binds syndecan-1, while processed laminin-5 does not. These results demonstrate that the LG4/5 modules within unprocessed laminin-5 permit its cell binding activity through heparan and chondroitin sulfate chains of syndecan-1 and reinforce previous data suggesting specific properties for the precursor molecule.

[Treatment of conjunctival epithelial tumors: brachytherapy with ruthenium-106]

INTRODUCTION

Treatment of conjunctival epithelial tumors is not standardized because it is difficult to compare large series in this rare disease. Surgical excision is usual, but the recurrence rate has led several authors to propose alternative therapies.

PATIENTS AND METHODS

During the past 20 years, brachytherapy using ophthalmic applicators has been developed and the results of different studies have confirmed the usefulness of this therapy. We report a retrospective study of 13 patients presenting with a conjunctival epithelial tumor treated with ruthenium106 applicators and followed up in our department since 1987.

RESULTS AND CONCLUSION

There was no recurrence during a mean follow-up of 48 months. Complications depended on the size of the area treated and the dose of radiation.

Heterologous human immunodeficiency virus type 1 lentiviral vectors packaging a simian immunodeficiency virus-derived genome display a specific postentry transduction defect in dendritic cells

Heterologous lentiviral vectors (LVs) represent a way to address safety concerns in the field of gene therapy by decreasing the possibility of genetic recombination between vector and packaging constructs and the generation of replication-competent viruses. Using described LVs based on human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus MAC251 (SIV(MAC251)), we asked whether heterologous virion particles in which trans-acting factors belonged to HIV-1 and cis elements belonged to SIV(MAC251) (HIV-siv) would behave as parental homologous vectors in all cell types. To our surprise, we found that although the heterologous HIV-siv vector was as infectious as its homologous counterpart in most human cells, it was defective in the transduction of dendritic cells (DCs) and, to a lesser extent, macrophages. In DCs, the main postentry defect was observed in the formation of two-long-terminal-repeat circles, despite the fact that full-length proviral DNA was being synthesized and was associated with the nucleus. Taken together, our data suggest that heterologous HIV-siv vectors display a cell-dependent infectivity defect, most probably at a post-nuclear entry migration step. As homologous HIV and SIV vectors do transduce DCs, we believe that these results underscore the importance of a conserved interaction between cis elements and trans-acting viral factors that is lost or suboptimal in heterologous vectors and essential only in the transduction of certain cell types. For gene therapy purposes, these findings indicate that the cellular tropism of LVs can be modulated not only through the use of distinct envelope proteins or tissue-specific promoters but also through the specific combinatorial use of packaging and transfer vector constructs.

[Efficacy and safety of substituting a twice-daily regimen of timolol with a single daily instillation of nonpreserved beta-blocker in patients with chronic glaucoma or ocular hypertension]

AIM

To evaluate the efficacy and safety of a single daily instillation of nonpreserved timolol in patients with chronic glaucoma or ocular hypertension previously treated with a twice-daily regimen of timolol 0.25% or 0.50%.

PATIENTS AND METHODS

A prospective open clinical trial was undertaken by 220 ophthalmologists in 435 patients with chronic glaucoma or ocular hypertension controlled with twice-daily instillations of timolol 0.25% or 0.50%. In this population, the previous regimen was substituted with a single daily instillation of preservative-free timolol 0.25% or 0.50% for 3 months. The changes in intraocular pressure (IOP) were recorded as well as local and systemic tolerance and patient compliance.

RESULTS

It was found that 398 patients (93.6%) maintained stable IOP: in 92%, IOP increased no more than 2 mmHg. The mean IOP was 17.0 +/- 2.2 mmHg at D0, 16.5 +/- 2.4 mmHg at D28/42 and 16.6 +/- 2.4 mmHg at D84. The proportion of patients with at least one ocular symptom upon instillation or at another time decreased (p<0.0001 and p=0.03, respectively). The proportion of conjunctival hyperemia reduced from 24.4% to 14.6% (p=0.0002). The rate of folliculopapillar reactions and superficial punctate keratitis was halved (p=0.005 and p=0.02, respectively).

CONCLUSION

During this study in daily practice, the switch from a twice-daily regimen of timolol to a once-daily application maintained stable intraocular pressure with a notable improvement in tolerance.

Keratinocyte motility induced by TGF-beta1 is accompanied by dramatic changes in cellular interactions with laminin 5

Transforming growth factor-beta1 (TGF-beta1) has the ability to induce epithelial cell migration while stopping proliferation. In this study, we show that, concomitant to promoting migration of normal human keratinocytes in vitro, TGF-beta1 induced a marked decrease in their adhesion capacity to processed alpha3-containing laminin 5-coated surfaces. Indeed, the expression levels of alpha3 and alpha6 integrin subunit mRNA and protein, as well as the cell surface alpha3beta1 and alpha6beta4 integrins, were down-regulated. Recent studies showed that keratinocytes over express and deposit laminin 5 during migration and we have shown that laminin 5 found in the matrix of TGF-beta1 induced migrating keratinocytes is present in its unprocessed form [Décline and Rousselle, 2001: J. Cell Sci. 114:811-823]. We show here that TGF-beta1 treatment of the cells promoted a significant increase in their adhesion to the alpha3 chain carboxy-terminal LG4/5 subdomain and that this interaction is likely to be mediated by a heparan sulfate proteoglycan type of receptor. Our results indicate that alpha6beta4 and alpha3beta1 integrin interactions with laminin 5 are diminished during migration while a specific interaction occurs between an additional cellular receptor and the alpha3 LG4/5 module present on unprocessed laminin 5.

ABO and Rh(D) blood typing on the PK 7200 with ready-to-use kits

The performance of ready-to-use kits was evaluated on the PK 7200 blood grouping system. The Olymp Group (kit 1) and Olymp Group II (kit 2) containing anti-A, -B, -AB, and -D reagents were tested for first and second determinations of A, B, and D antigens. More than 500 RBC samples, including several variant ABO and D phenotypes, were evaluated for specificity, repeatability, reproducibility, and sensitivity. Specificity was tested with well-characterized reagent RBCs. Repeatability was established by at least 12 assays per run with three reagent RBCs, and reproducibility was established on one run per day for 5 days. No discrepancy was observed in ABO and D determinations with either kit. In repeatability, three discrepancies were found with group A and B RBCs with kit 1. In reproducibility, no discrepancies were observed. The kit 1 anti-A reagent detected A3 but not Ax RBCs and anti-AB detected both. A B3 RBC was detected by both kits. Among eight weak D phenotypes, six were positive with kit 1. With kit 2, only one of five weak D phenotypes was detected.

Upstream open reading frames regulate translation of Mona/Gads adapter mRNA in the megakaryocytic lineage

Mona, also called Gads, is a molecular adapter that plays a key role in T-cell and platelet signalling by linking the adaptors Src homology 2 domain-containing leukocyte phosphoprotein of 76 kDa (Slp-76) and linker for activation of T cells (LAT) upon T-cell receptor and collagen receptor activation. Platelets express a specific form of Mona mRNA, called 1B, which is transcribed from a megakaryocyte-specific promoter. Mona 1B mRNA differ from 1A transcripts found in T cells and some myeloid cells only by the 5'UTR. We report here that 1B mRNA expressing cells do not express detectable amounts of Mona protein, in contrast to 1A expressing cells, and we show that 1B 5'UTR contains upstream open reading frames (uORFs). Mutating the corresponding uAUG restored efficient Mona translation, or that of an unrelated ORF. This suggested that Mona protein expression in 1B mRNA expressing cells is tightly controlled at the translational level. Accordingly, Mona protein was not detected in resting platelets. Strikingly, platelet activation by thrombin resulted in the rapid induction of Mona protein expression, suggesting that translation inhibition of 1B mRNA may be relieved in activated platelets.

Cyclosporin A inhibits dendritic cell maturation promoted by TNF-alpha or LPS but not by double-stranded RNA or CD40L

Here, we investigated the influence of cyclosporin A (CsA) on dendritic cell (DC) generation. With this aim, human DC were propagated from monocytes in serum-free medium with granulocyte macrophage-colony stimulating factor and interleukin-4. DC were then exposed to tumor necrosis factor alpha (TNF-alpha) for maturation. Our results show that CsA does not impair commitment of monocytes into DC, as assessed by loss of CD14 and increase of CD40 and CD1a. However, TNF-alpha-induced DC maturation was affected, as CsA-treated DC expressed lower levels of human leukocyte antigen and costimulatory molecules but sustained levels of CD1a, and less DC expressed DC-lysosomal-associated-membrane-protein (LAMP) and CD83. Accordingly, CsA inhibited the allostimulatory and accessory cell functions of DC. Surprisingly, when other maturation stimuli were used, we observed that CsA significantly inhibited maturation induced by lipopolysaccharides but not by polyribocytidylic acid or CD40 ligand, as assessed by DC phenotype and functions. Therefore, our results indicate that CsA may differentially affect DC maturation.

Transcriptional regulation of the human MDR1 gene at the level of the inverted MED-1 promoter region

The typical multidrug resistance phenotype (MDR), the major cause of failure of cancer chemotherapy, is the result of the overexpression of the human MDR1 gene, the regulation of which is still incompletely understood. Using several EMSA experiments, we have identified a new regulatory sequence located from -103 to -98 bp relative to the +1 start site in the MDR1 promoter region. This sequence, which we called inverted MED-1, acts as a cis-activator for this gene. In transient transfection experiments of highly resistant human lymphoblastic CEM/VLB5 cells, its deletion from the promoter region is responsible for 60% inhibition of the MDR1 transcriptional activity. This sequence specifically binds a nuclear protein of about 150-160 kDa. We showed that its binding capacity is related to the chemoresistance level of the studied cell lines and may reflect the increased transcriptional activity of the MDR1 gene in multidrug-resistant cells.

Generation of monocyte-derived dendritic cells in patients with hereditary hemochromatosis

Hereditary hemochromatosis (HH) is a common genetic disease with autosomal recessive transmission and is characterized by a dysregulation of iron metabolism, leading to serum iron overload and its progressive accumulation in most body tissues. The effects of HH on the immune system include altered lymphocytosis and functions of monocytes. Moreover, monocytes can differentiate into dendritic cells (DCs), which play crucial roles in the immune response (capture, processing, and presentation of antigen to effector T cells) and this process was shown to be impaired in several pathologies. The aim of this study was to determine whether the monocytes from HH patients still displayed the ability to differentiate into DCs. To that purpose, purified monocytes from healthy donors and HH patients were cultured in the appropriate medium. The results showed no phenotypic and functional differences, at both the immature and the mature stages. Furthermore, our work reports altered lymphocytosis with expanded CD8+CD28- T cell subset. These monocyte-derived DCs could therefore be a solid vector for DC-based immunotherapy and a powerful tool for investigating the immune regulatory loops and especially the biological relevance of the expanded CD8+CD28- T cells since this population has also been described as suppressor T cells.

Transcriptional regulators of the human multidrug resistance 1 gene: recent views

The multidrug resistance (MDR) phenotype is the major cause of failure of cancer chemotherapy. This phenotype is mainly due to the overexpression of the human MDR1 (hMDR1) gene. Several studies have shown that transcriptional regulation of this gene is unexpectedly complex and is far from being completely understood. Current work is aimed mainly at defining unclear and new control regions in the hMDR1 gene promoter as well as clarifying corresponding signaling pathways. Such studies provide new insights into the mechanisms by which xenobiotic molecules might modify the physiological hMDR1 expression as well as the possible role of oncogenes in the pathological dysregulation of the gene. Here we report recent findings on the regulation of hMDR1 which may help define specific targets aimed at modulating its transcription.

Genomic organization and restricted expression of the human Mona/Gads gene suggests regulation by two specific promoters

Monocytic adaptor (Mona) also known as Gads is a Grb2-related adaptor whose expression is restricted to hematopoietic cells. It plays an important role in intracellular signaling in T cells, monocytic cells, and platelets. Here we investigated the regulatory aspects of Mona expression in human hematopoietic cells. This was carried out by combining nucleotide sequence analyzes and experimental approaches. We confirmed that Mona expression is restricted to T-cell, myeloid and platelet lineages. In the various cells examined, we detected two major Mona transcripts (1.9 and 4 kb), likely resulting from the alternative use of two polyadenylation sites. Consequently, Mona transcripts of the same size have identical 3' untranslated region (UTR), irrespective of the cell type. In contrast, Mona transcripts contain either 5' UTR-1A or -1B exons, that were detected in a cell-lineage specific manner. Thus, T cells and several myeloid cell lines express 5' UTR-1A-containing transcripts, whereas platelets and cell lines exhibiting megakaryocytic potential express 5' UTR-1B-containing transcripts. Interestingly, 5' UTR-1A is generated from an exon located approximately 45 kb upstream of exon 1B. This suggested that lineage-restricted transcription of the Mona gene is controlled by specific promoters. Indeed, 2-kb genomic fragments upstream of each 5'-UTR showed lineage-restricted ability to drive expression of luc reporter gene.

High levels of transduction of human dendritic cells with optimized SIV vectors

As major antigen-presenting cells and effectors in the maintenance of tolerance, dendritic cells (DCs) are key cells of the immune system and can thus be envisioned to have roles in immunotherapy strategies. We, and others, previously showed that simian immunodeficiency virus (SIV)-derived lentiviral vectors were able to deliver a gene into human differentiated DCs. We describe here the upgrading of the SIV vector system and the improvements of the transduction protocol, which allowed us to transduce more than 90% of human monocyte-derived DCs. We developed new SIV lentiviral vectors carrying SIV splice regulatory elements and either the woodchuck hepatitis virus regulatory element (WPRE) or the murine phosphoglycerate-kinase 1 (PGK) promoter. We show that insertion of the WPRE in the SIV vector is detrimental to gene transfer in DCs, while this sequence increases transgene expression in 293T cells. Using an optimized SIV vector, high levels of transgene expression were obtained in more than 30% of human DCs at a multiplicity of infection (MOI) of 1, and close to 100% using a MOI of 20. VSV-G pseudotyped vectors generated with only gag, pol, tat, and rev helper functions failed to transduce DCs. This defect was completely rescued when the SIV accessory gene vpx was provided in trans in vector-producing cells. Genetically modified DCs were shown to behave as bona fide DCs in both allogenic and autologous mixed leukocyte reactions. These findings allow us to propose an optimal system for efficient and safe DC transduction with improved SIV vectors.

p60(v-src) and serum control cell shape and apoptosis via distinct pathways in quail neuroretina cells

We made use of QNR cells transformed by a thermosensitive (tsNY68) strain of the Rous sarcoma virus (RSV) to compare the effect of p60(v-src) and serum in cultured nerve cells. In this system, both p60(v-src) heat inactivation and serum removal resulted in growth arrest in G1. In both cases, growth arrest was reversible since cell proliferation was rapidly re-induced following respectively p60v-src renaturation or serum re-addition. However, cells did not fully recover their ability to grow in soft agar, suggesting that, in contrast to the cell cycle machinery, the transforming capacities of these cells have been irreversibly altered. We found that p60(v-src) kinase activity prevented detachment from the substratum and cell death following serum removal. Thermal inactivation of p60(v-src) at restrictive temperature (41.5 degrees C), but not serum removal, resulted in dramatic morphological changes, which occurred 4 h after temperature shift up to 41.5 degrees C. Later on, typical features of apoptotic cells could be observed. Cell death was greatly reduced by the caspase-3 inhibitor ZVAD.FMK, but not by the caspase-1 inhibitor Ac-YVAD.CHO. Together, these results suggested that p60(v-src) and serum factors act on distinct pathways, at least in part. In an attempt to identify the signalling pathways involved in the cell response to p60(v-src) down regulation, we found that Erk and Rac were rapidly inactivated following temperature shift up to 41.5 degrees C. Thus, the combined effects of p60(v-src) and serum factors on the cytoskeleton dynamics and the apoptosis machinery are essential for full neoplastic transformation of neuroretina cells.

Nrh, a human homologue of Nr-13 associates with Bcl-Xs and is an inhibitor of apoptosis

In search of human homologues of the anti-apoptotic protein Nr-13, we have characterized a human EST clone that potentially encodes a protein, which is the closest homologue of Nr-13 among the Bcl-2 family members, to date known, in humans. Phylogenetic analyses suggest Human nrh, Mouse diva/boo and Quail nr-13 to be orthologous genes. The nrh gene has the same overall organization as nr-13 and diva/boo with one single intron interrupting the ORF at the level of the Bcl-2-homology domain BH2. RT-PCR-based analysis of nrh expression indicated that this gene is preferentially expressed in the lungs, the liver and the kidneys. Interestingly, two in frame ATG codons can lead potentially to the synthesis of two products, one of them lacking 10 aminoacids at the N-terminal end. Sequence alignment with Nr-13 and Diva/Boo in addition to secondary structure prediction of the nrh transcript suggested that the shortest protein will be preferentially synthetized. Immunohistochemical analyses have revealed that Nrh is associated with mitochondria and the nuclear envelope. Moreover, Nrh preferentially associates with the apoptosis accelerator Bcl-Xs and behaves as an inhibitor of apoptosis both in yeast and vertebrate cells.

Generation of helper and cytotoxic CD4+T cell clones specific for the minor histocompatibility antigen H-Y, after in vitro priming of human T cells by HLA-identical monocyte-derived dendritic cells

BACKGROUND

There is now convincing evidence that minor histocompatibility antigens (mHag) may play a significant role in the pathogenesis of graft-versus-host disease after HLA-identical bone marrow transplantation. Indeed, in this clinical situation, T cells specific for mHag have been isolated. Here, we addressed whether one can generate mHag-specific T cells in vitro, without any in vivo immunization, among healthy blood donors.

METHODS

We used monocyte-derived dendritic cells (Mo-DCs) as antigen presenting cells to induce primary responses between healthy HLA-identical siblings, in mixed lymphocyte dendritic cell reactions (MLDCRs).

RESULTS

We show that CD4+ T-cell clones, specific for the mHag H-Y, can be generated in vitro. These clones were derived from a gender-mismatched positive MLDCR pair of HLA-identical siblings and were restricted by the HLA DQB1*0502 molecule. In addition, these CD4+ T clones were also able to lyse allogeneic targets with the same pattern of restriction and specificity than helper function. Finally, acute myeloid leukemia (AML) blast cells were susceptible to lysis by these clones.

CONCLUSIONS

Altogether, these results predict that Mo-DCs could help to generate class II-associated, mHag-specific, T-cell lines or clones in vitro, between healthy blood donors, without any need of transplantation-mediated immunization.

Clinical applications of flow cytometry and cell immunophenotyping to companion animals (dog and cat)

Clinical applications of flow cytometry to certain diseases of the dog and cat are now possible. The utility of such applications for diagnosis, prognosis and follow-up are illustrated here by a number of examples: feline AIDS resulting from FIV infection, Leukocyte Adhesion Deficiency in Irish setters, deep pyoderma in German shepherds, Immune-mediated Thrombocytopenia, canine Systemic Lupus Erythematosus and Leishmaniasis, Leukemia and Lymphoma.

Heparins and blood polymorphonuclear stimulation in haemodialysis: an expansion of the biocompatibility concept

BACKGROUND

At the concentrations used in haemodialysis and in a dose-dependent way, unfractionated heparin (UFH) and, to a lesser degree, a low-molecular-weight heparin (LMWH) stimulate polymorphonuclear cells (PMN) in vitro, and could act in synergy with the stimulatory effect of dialysis membranes in vivo. To examine this hypothesis, we studied the effects of different heparin types and regimens on blood PMNs during haemodialysis sessions.

METHODS

Ten haemodialysed patients were studied during regular dialysis sessions on a cellulose triacetate membrane (CT 110 G; 1.10 m(2); Baxter), with four different random heparin protocols: one high-UFH regimen (HHR) at 90 IU/kg body-weight (b.w.) and one low-UFH regimen (LHR) at 50 IU/kg b.w., and with a LMWH (nadroparin calcium) at 85 (HHR) or 45 (LHR) IU/kg b.w. Blood granulocytes, platelet counts, and plasma granulocyte degranulation products (elastase, lactoferrin) were measured serially during 4 h dialysis sessions.

RESULTS

After 10 min, the reduction in PMNs with UFH was 29.5% for HHR (P<0.01) and 28.5% for LHR (P<0.01), and only 16.8 and 18.6% with LMWH (NS), significantly higher for HHR with UFH than with LMWH (P<0.01). At 60 min, the elastase increase with HHR was greater, 61% with UFH (P<0.01) and 37.8% with LMWH (P<0.01), significantly higher than LHR for UFH (P<0.05) or LMWH (P<0.05). The overall decrease in platelets (with LMWH P<0.01) and the overall increase in lactoferrin (P<0.001) were not different between heparinization procedures.

CONCLUSION

Under a conventional heparin regimen, the PMN variation during the course of the dialysis session suggests a more biocompatible effect of LMWH over UFH. In addition, the variation of elastase favours the lower dose, whatever the type of heparin. Heparin type and dose should therefore be considered in studies addressing biocompatibility in haemodialysis: a low dose of LMWH may be viewed as a better biocompatible treatment with regard to leukocyte stimulation.

Modulation of the typical multidrug resistance phenotype by targeting the MED-1 region of human MDR1 promoter

Multidrug resistance of cancer (MDR) is the major cause of failure of chemotherapy. The typical MDR phenotype is due to the overexpression of membrane proteins among which the main representative is P-glycoprotein (Pgp) encoded by the MDR1 gene. Many attempts to modulate MDR by chemosensitizers have been unsuccessful in human therapy due to their intrinsic toxic effects. In an effort to modulate the MDR phenotype efficiently we designed an antisense and a transcriptional decoy strategy targeting the TATA-less human MDR1 gene promoter. The choice of the start point of transcription in a multiple start site window is related to an upstream MED-1 cis-element, the sequence and configuration of which are specific to human MDR1 gene expressed in Pgp-overproducing cancer cells. A 12mer antisense oligodeoxynucleotide (ODN) and a 12mer double-stranded ODN, both containing the MED-1 sequence, were designed and efficiently vectorized into the nucleus with the chimerical MPG peptide. A synthetic cellular model (NIH-EGFP) and highly resistant human CEM/VLB0.45 leukemia cells, significantly responded to transfection with the ODN/MPG complex. The level of EGFP fluorescence in NIH-EGFP cells decreased, and thus its production, and viability of CEM/VLB0.45 cells decreased by 63% in the presence of vinblastine, revealing that their resistance to the anticancer drug was reversed. These results open new insights into transcriptional decoy and anti-gene therapies of MDR cancers that overproduce Pgp. Gene Therapy (2000) 7, 1224-1233.

Canine large granular lymphocyte leukemia and its derived cell line produce infectious retroviral particles

We describe a case of large granular lymphocyte (LGL) leukemia in a dog that we followed over a period of 2 years. Analysis of a hematological profile revealed lymphocytosis (19,500 lymphocytes per microliter; reference values, 1,000-4,800 lymphocytes per microliter), with a majority of LGL on the blood smear. LGL is defined as a lymphoid subset comprising 10% of peripheral blood mononuclear cells and corresponding to either CD3- CD8- NK cells or CD3+ CD8+ T cells. The cells are characterized by abundant basophilic cytoplasm containing distinct granules of variable size and number. The characteristic phenotype of our leukemic LGL is of a cytotoxic T cell, CD3+ and CD8+. A new cell line, DLC 02, was established from the peripheral lymphocytes of the leukemic dog. Particles with type C retroviral morphology were found in ultrathin sections of DLC 02 cell pellets. These particles were found to have a sucrose gradient density of 1.17 g/liter and a reverse transcriptase activity with an Mn2+ preference, suggesting that they correspond to a mammalian type C oncovirus.