Biomedical subjects
Publications and source records attributed to J M Wilson.
The past year has seen a proliferation in the use of recombinant, replication-defective adenoviruses for experimental models of gene therapy. The fact that adenovirus infects most cell types with no requirement for cell division, combined with the high titers and high efficiency of gene transfer obtainable with recombinant adenovirus, make it a promising system for in vivo human gene therapy.
Liver-directed gene therapy holds great promise for the treatment of inherited metabolic disease. Two strategies have emerged. Ex vivo gene therapy involves the transplantation of autologous hepatocytes transduced with recombinant retroviruses while in culture. The feasibility of this approach has been demonstrated in several animal models, and a human trial has been initiated. An alternative strategy uses recombinant viruses to deliver the transgene directly to hepatocytes in vivo.
Previous methods of in vivo gene transfer to differentiated neurons of the adult mammalian brain have been inefficient and associated with technical problems. We have therefore developed a model system of direct gene transfer using a replication-defective adenoviral vector containing a beta-galactosidase gene to transduce brain neurons. Following injection of purified high titre recombinant adenovirus into the caudate putamen of seven week old mice, lacZ activity was evident in neural components of the central nervous system (CNS) for at least 8 weeks post infection. The efficiency of adenoviral gene transfer was very high compared to other techniques, suggesting an attractive and efficient alternative for neuronal gene transfer in vivo.
We describe the use of a human bronchial xenograft model for studying the efficiency and biology of in vivo gene transfer into human bronchial epithelia with recombinant E1 deleted adenoviruses. All cell types in the surface epithelium except basal cells efficiently expressed the adenoviral transduced recombinant genes, lacZ and CFTR, for 3-5 weeks. Stable transgene expression was associated with high level expression of the early adenoviral gene, E2a, in a subset of transgene expressing cells and virtually undetectable expression of the late adenoviral genes encoding the structural proteins, hexon and fiber. These studies begin to address important issues that relate to safety and in vivo efficacy of recombinant adenoviruses for gene delivery into the human airway.
We have evaluated the biological efficacy of E1-deleted adenoviruses in baboons for lung-directed gene therapy of cystic fibrosis (CF). The experimental design attempted to simulate a phase I clinical trial with animals receiving a single dose of virus to an isolated pulmonary segment. A total of 14 animals divided into four groups, each of which received escalating doses of virus, were used. Individual animals were necropsied 4 and 21 days after gene transfer and tissues were carefully surveyed for gene expression. Expression of the transgene was localized primarily to the area into which it was infused; the efficiency of recombinant gene expression and the abundance of transgene sequences were proportional to dose and both diminished with time. Transgene expression was found predominantly in alveolar cells with patches of expression in the proximal and distal airway. Analysis of adenoviral protein expression within transgene-expressing cells revealed infrequent expression of the E2a gene and no detectable expression of late genes (i.e., fiber protein). These results suggest that recombinant adenovirus can be used to transfer genes efficiently to the lung of nonhuman primates and that therapeutic strategies of cystic fibrosis may require repetitive administration with current vectors.
In preparation for human trials of gene therapy for cystic fibrosis (CF), we performed a preclinical study of gene transfer into the lungs of baboons. Recombinant adenovirus vectors containing expression cassettes for human cystic fibrosis transmembrane conductance regulator (CFTR) and Escherichia coli beta-galactosidase (lacZ) were instilled through a bronchoscope into limited regions of lung in 14 baboons. A detailed accounting of the extent, distribution, and duration of gene expression is contained in a companion article (Engelhardt et al., 1993b). In this article, we report the results of toxicity studies in which clinical laboratory tests, chest radiographs, and necropsy studies were used to detect adverse effects. The only adverse effect noted was a mononuclear cell inflammatory response within the alveolar compartment of animals receiving doses of virus that were required to induce detectable gene expression. Minimal inflammation was seen at 10(7) and 10(8) pfu/ml, but at 10(9) and more prominently at 10(10) pfu/ml, a perivascular lymphocytic and histiocytic infiltrate was seen. The intensity of inflammation increased between 4 and 21 days. At its greatest intensity, there was diffuse alveolar wall damage with intra-alveolar edema. Airways were relatively spared, despite the intensity of alveolar inflammation. Clinical tests did not accurately reflect the presence of lung inflammation, with the exception of chest radiographs which revealed alveolar infiltrates, but only in regions of lung having the greatest intensity inflammation. We conclude that adenovirus-mediated gene transfer into the lungs of baboons is associated with development of alveolar inflammation at high doses of virus.
The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes a cAMP-activated chloride (Cl-) channel, and expression of the full length gene in vitro is sufficient to correct the Cl- conductance defect that is characteristic of cystic fibrosis (CF) epithelial cells. Alternatively spliced forms of CFTR mRNA have been identified in several tissues from normal individuals. One of the alternative transcripts, often present at high levels, results in the in-frame deletion of exon 9. Translation of this transcript would result in a CFTR protein missing the amino terminal portion of the first nucleotide binding fold (NBF). To evaluate the possible function of this form of CFTR, a cDNA representing this transcript (CFTR delta 9) was transduced into CFPAC cells, which are derived from a CF patient. CFTR delta 9 RNA was expressed in the transduced cell lines, but only immature, incompletely glycosylated protein was detectable by Western blot analysis. No increase in cAMP-activated anion permeability was detectable by 125I efflux assay or by means of the halide sensitive dye 6-methoxy-N-(3-sulfopropyl) quinolinium (SPQ). In a second assay system, in vitro synthesized mRNA representing CFTR delta D9 was injected into Xenopus oocytes, but expression of this alternatively spliced form of CFTR was not associated with the appearance of Cl- conductance. These results suggest that the protein produced by the CFTR delta 9 transcript is not properly processed and is not capable of generating Cl- conductance in response to cAMP. Whether this alternative transcript has some other function or represents 'noise' in the mRNA splicing mechanism remains unresolved.
Cystic fibrosis (CF) is caused by mutations in the gene encoding a chloride channel called the CF transmembrane conductance regulator (CFTR). A single mutation in this gene, deletion of three nucleotides that leads to the absence of phenylalanine 508 (i.e., delta F508), is found on 70% of all CF chromosomes. To explore the molecular mechanism(s) responsible for defective chloride transport in patients with CF, we have studied the processing, localization, and function of wild type (W.T.), delta F508 and G551D CFTR (a G-->D missense mutation at position 551) in retrovirus transduced L cells. Cell transduced with W.T. CFTR expressed a 170 kd CFTR protein that was endoglycosidase H (Endo H) resistant, localized to the plasma membrane, and generated a cAMP-mediated anion conductance (GCl) when stimulated with standard concentrations of forskolin (5 microM), cpt cAMP (400 microM) and IBMX (100 microM). The G551D CFTR was indistinguishable from W.T. CFTR with respect to post-translational processing and localization, but it did not produce a cAMP-activated GCl in response to the standard stimulation cocktail. However, raising the IBMX concentration to 4 mM produced GCl in G551D expressing cells. Cells transduced with delta F508 CFTR expressed an Endo H sensitive CFTR protein (approximately 140 kd) that was found in a cytosolic, perinuclear location. These cells did not respond to the standard cocktail, but approximately 20% of cells increased GCl when the cocktail contained 4 mM IBMX.(ABSTRACT TRUNCATED AT 250 WORDS)
The majority of human peripheral gamma delta T cells express antigen receptors using the V gamma 9 and V delta 2 gene products. Cells of this subset have been previously shown to uniformly recognize mycobacteria regardless of their V-(D)-J junctional sequences in an MHC-unrestricted manner. This reactivity superficially resembles activation of alpha beta cells by bacterial superantigens, which are thought to be presented by monomorphic regions of MHC class II molecules. It is not known whether presentation of the mycobacterial antigen to V gamma 9/V delta 2 T cells is also mediated by class II MHC molecules. In order to examine the similarity between presentation of bacterial superantigens to alpha beta T cells and the presentation of mycobacteria to gamma delta T cells we have studied the role of class II MHC molecules in presentation of the mycobacterial antigen AP-MT to V gamma 9/V delta 2 clones. Activation of gamma delta T cells by AP-MT required direct contact with antigen presenting cells, indicating that an interaction with cell surface molecules on antigen presenting cells is required. Class II MHC molecules were neither sufficient nor necessary for effective presentation of AP-MT to the gamma delta T cells, as transfectants expressing class II MHC molecules were unable to present, whereas cell lines lacking expression of MHC class II molecules could present this mycobacterial antigen.(ABSTRACT TRUNCATED AT 250 WORDS)
Experiments were conducted to identify neurons in the bovine brain that express the LHRH gene and to determine whether LHRH mRNA levels are influenced by the ovaries. Two groups of postpubertal heifers were utilized: heifers killed during the mid-luteal phase of the estrous cycle (LUTEAL, n = 5) and heifers killed 14-16 wk following ovariectomy (OVX, n = 5). In situ hybridization was performed through use of a 32P-end-labeled deoxyoligonucleotide (59 mer) complementary to the human LHRH mRNA sequence. LHRH-expressing neurons were identified in the diagonal band of Broca, the preoptic area, and the anterior hypothalamus in a manner consistent with immunocytochemical localization. Reduced silver grains, proportional to LHRH mRNA content, were quantified (in pixels, 45x objective) with an image analysis system. Expected serum hormone concentration differences between endocrine states were confirmed by radioimmunoassay for progesterone (LUTEAL > OVX, p < 0.01) and for LH (OVX > LUTEAL, p < 0.01). Compared to the OVX group, LUTEAL heifers had 34% fewer LHRH-expressing neurons (p < 0.05); on the average, these neurons possessed 28% fewer pixels/cell (p < 0.01), indicating fewer copies of LHRH mRNA per cell. When the numbers of pixels in all labeled cells were totalled, LUTEAL animals had 57% fewer pixels (p < 0.05) than did the OVX females--probably reflecting a decrease in LHRH synthetic capacity in the LUTEAL animals. Therefore, during the mid-luteal phase of the bovine estrous cycle, ovarian steroid (i.e., luteal progesterone) suppression of LHRH release (as reflected by serum LH) is coincident with decreased LHRH mRNA in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)
Currently, treatment for rheumatoid arthritis and other inflammatory arthropathies is often ineffective in ameliorating the progression of the disease, particularly the invasive destruction of cartilage and bone by rheumatoid synovium. Multiple aspects of this inflammatory process are mediated by the synovial lining cells (synoviocytes). Genetic modification of these cells in vivo represents a potential method for the treatment of these conditions. In this report, we describe a novel technique for the genetic transduction of synovial lining cells in vivo using recombinant adenoviral vectors and intraarticular injection techniques. Purified high titer suspensions of a recombinant adenoviral vector containing the gene for Escherichia coli beta-galactosidase (AdCMVlacZ) were directly injected into the hind knees of New Zealand white rabbits. Synovial tissues were then examined for transgenic lacZ expression using a combination of in situ staining for beta-galactosidase activity, immunohistochemical staining, and transmission electron microscopy. High efficiency gene transfer and lacZ expression was observed in both type A and type B synoviocytes throughout the articular and periarticular synovium of the rabbit knee, with continued expression of transgenic lacZ detected for > or = 8 wk after infection.
To evaluate the long-held concept that acidic guanidines lack glycemic effects, guanidinoalkanoic acids and the biguanide metformin (positive control) were administered to KKAy mice, a model of noninsulin-dependent diabetes. Two acidic guanidines, 3-guanidinopropionic acid (3-GPA) and guanidinoacetic acid, decreased the plasma glucose level; other compounds were ineffective. 3-GPA was more potent than even metformin. Insulin suppression tests in KKAy mice indicated that improved insulin sensitivity was the mode of action for 3-GPA. Glycemic effects in KKAy mice resulted from increased glucose disposal whereas gluconeogenesis, hepatic glycogen content and intestinal glucose absorption were unchanged. 3-GPA's glycemic effect was corroborated in two other models of noninsulin-dependent diabetes. In ob/ob mice, the compound reduced hyperglycemia, polyuria, glycosuria and hyperinsulinemia. In insulin-resistant rhesus monkeys, it increased the disappearance of i.v. glucose. The glycemic action of 3-GPA required the presence of some circulating insulin as well as hyperglycemia because the compound was ineffective in normoglycemic mice, insulinopenic Chinese hamsters and streptozotocin-diabetic rats. These data indicate that acidic guanidine derivatives can ameliorate hyperglycemia in animal models of noninsulin-dependent diabetes. Because acidic derivatives uniquely lack the propensity of guanidine compounds for inducing lactic acidosis, our finding suggests a new approach for developing improved antidiabetes compounds from this chemical class.
The polar lipid composition of representative strains of Bacteroides fragilis, Prevotella intermedia, P. melaninogenica and Capnocytophaga ochracea was determined. Samples were analysed by FAB-MS. Forty major peaks had m/z values expected for known carboxylate anions, ranging from m/z 211 (tridecenoate) to m/z 381 (pentacontanoate). A further fifty-five major peaks were studied between m/z 561 and m/z 722. Forty-five anionic phospholipids of several series were identified. The Pearson coefficient of linear correlation revealed the similarity of the P. intermedia spectra from repeat experiments (r = 0.98), as opposed to inter-species comparisons (0.55, 0.22, 0.20). Thus, FAB-MS rapidly yields data on molecular species within phospholipid families not readily obtained by other means. The data obtained may have chemotaxonomic potential.
Many attempts have been made to treat metabolic diseases of the liver. One approach, called ex vivo gene therapy, is based on correcting the genetic defect in the patient's hepatocytes. In this model, the liver is resected and hepatocytes are isolated, plated in culture, and genetically corrected with recombinant retroviruses. The cells are then harvested and infused into the portal circulation, where they seed in the sinusoids of the liver. In this study, a canine model was used to develop an approach to ex vivo gene therapy that requires only one surgical procedure. The basic concept is to place a catheter in the mesenteric circulation at the time of liver resection that can be used subsequently to deliver hepatocytes into the liver. With four 18 to 28 kg mongrel dogs, a laparotomy was performed, the left lateral segment of the liver was resected, and a 9.5 Fr Hickman catheter was introduced into the inferior mesenteric vein. At 10 days, the catheter was studied angiographically and removed. The catheter remained patent and was easily removed without untoward effects. A subsequent necropsy was performed to evaluate the consequences of this procedure. There was no hematoma at the site of the catheter placement or evidence for intraportal clot. This approach has been used in subsequent studies to treat a patient with familial hypercholesterolemia.
Two histochemical marker genes, Drosophila alcohol dehydrogenase (ADH) and human placental alkaline phosphatase (ALP), were cloned into the recombinant retroviral vectors pLJ and pgag beta-actin. The resulting vectors were transfected into retroviral producer cell lines, psi CRE and psi CRIP, and stable recombinant retrovirus producers were isolated. Recombinant virus was harvested and used to transduce genes into several cell lines, singly or in conjunction with lacZ (Escherichia coli beta-galactosidase)-containing retrovirus. Cell lines were then stained using standard histochemical methods for recombinant gene expression. We found that multiple gene products could be identified in the same cell populations and in the case of ALP and beta-galactosidase, in the same cells. The resulting reagents should be useful for a variety of cell-marking studies including those involving multiple clonal analysis and developmental studies for gene therapy.
Use of the capillary bed of skeletal muscle as an in vivo recipient site to transplant autologous endothelial cells that have undergone gene transfer ex vivo has considerable potential as a technique of somatic gene therapy. Here we document a previously unrecognized capacity of endothelial cells to adhere and incorporate spontaneously into confluent endothelial cell monolayers in vitro and in vivo. This spontaneous adhesion and incorporation of endothelial cells enabled us to seed lacZ-transduced endothelial cells into the wall of skeletal muscle capillaries of the hindlimb of the rat. Certain transduced endothelial cells became incorporated within the capillary wall, whereas others remained within the capillary lumen where they formed focal, electron-dense, contacts with host endothelium. lacZ expression in the capillary bed was documented for up to 1 month after transplantation. Use of the intact capillary bed of skeletal muscle as an in vivo recipient site for transduced, autologous endothelial cells holds promise as a strategy for somatic gene therapy to treat various genetic and acquired human diseases.
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