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Biomedical subjects

G Wick

Publications and source records attributed to G Wick.

At least 19 recordsLinked to original sources
PubMed1996

Endothelial cell apoptosis is a primary pathogenetic event underlying skin lesions in avian and human scleroderma.

The mechanism that may cause degenerative fibrotic skin lesions was studied in situ using skin biopsies from patients with systemic sclerosis (SSc), localized scleroderma, or keloids, and at the initial disease stage in the University of California at Davis (UCD) lines 200/206 chickens, which develop a hereditary systemic connective tissue disease resembling human SSc and permit study of disease stages not accessible in humans. Frozen skin sections were analyzed simultaneously for apoptosis by terminal deoxynucleotidyl transferase-mediated FITC-dUTP nick end labeling and indirect immunofluorescence staining of cell markers with tetramethylrhodamine isothiocyanate conjugates. The results showed that endothelial cells are clearly the first cells to undergo apoptosis in the skin of UCD-200/206 chickens, a process that seems to be induced by anti-endothelial cell antibodies. In human fibrotic skin diseases, apoptotic endothelial cells could only be detected in early inflammatory disease stages of SSc and localized scleroderma.

Adolescent↗
PubMed1996

Preparation and characterization of poly-(D,L-lactide-co-glycolide) and poly-(L-lactic acid) microspheres with entrapped pneumotropic bacterial antigens.

Poly-(lactide-co-glycolide) microspheres with entrapped antigen have shown considerable promise as controlled release vaccines. To enhance the immunomodulatory effect of LW 50020, a bacterial lysate of seven common respiratory pathogens used perorally as an immunomodulator, we prepared poly-(D,L-lactide-co-glycolide) (PLG) and poly-(L-lactic acid) (PLA) microspheres with entrapped immunomodulator by solvent evaporation or solvent extraction double emulsion techniques. Physical properties, such as particle size, LW 50020 entrapment rate, antigen release patterns and morphological characteristics were investigated. All preparations displayed a high degree of antigen loading up to 95%, whereas size, surface morphology and antigen release patterns were significantly influenced by the method of preparation and the polymer components used. Solvent evaporation microspheres are porous particles from 0.8 micron to 2.0 microns in diameter, that show a rapid antigen release for PLG, and a moderate antigen release for PLA microspheres within 33 days. Solvent extraction microspheres have proven to be particles from 1.1 microns to 5.0 microns in diameter showing a smooth surface and a medium antigen release rate over 33 days. SDS-PAGE and immunoblotting of extracted antigen confirmed that the molecular weight and antigenicity of the immunomodulator remained unaltered by the entrapment procedure.

Adjuvants, Immunologic↗
PubMed1996

Coexpression of heat-shock protein 60 and intercellular-adhesion molecule-1 is related to increased adhesion of monocytes and T cells to aortic endothelium of rats in response to endotoxin.

Bacterial cell-wall lipopolysaccharide (LPS) is the main endotoxin contributing to local inflammation and systemic toxicity during Gram-negative infections and induces aortic endothelial injury with or without cell death and replication followed by increased leukocyte adhesion. Heat-shock protein (hsp) 60 is under study in our laboratory as a potential antigen inducing immunologic attack to endothelial cells in atherogenesis. To investigate the mechanism of LPS-induced endothelial injury and the phenotypes of adhering cells, Lewis rats were treated in vivo or, in aortic organ cultures, with LPS to determine the expression of intercellular-adhesion molecule-1 (ICAM-1) and hsp60 on aortic endothelium and to characterize phenotypes of adhering leukocytes. Increased ICAM-1 expression by aortic endothelium was observed as early as 3 hr after LPS injection and persisted up to 72 hr, whereas elevated levels of hsp60 were found between 6 and 48 hr. In vitro application of various types of stress, such as LPS, H2O2, and high temperature, not only stimulated endothelial expression of hsp60 but, concomitantly, that of ICAM-1. The number of adhering leukocytes was significantly increased on aortic endothelium 6 hr after LPS administration, and the predominant leukocytes adhering to stressed endothelium were monocytes (80%) and T lymphocytes (8 to 20%). In organ cultures of rat aortic intimal, LPS, and H2O2 evoked increased leukocyte adhesion, which proved to be selective, because adherent leukocytes were mostly Ia+ monocytes and T cells, i.e., activated. Adhering T cells were gamma/delta antigen-receptor positive in 8 to 16% after LPS stress, whereas these cells amount to only 2 to 4% of peripheral blood T cells. Blocking of adhesion molecules ICAM-1, LFA-1 alpha, and/or LFA-1 beta reduced adhesion up to 34%. Increased coordinated LPS-dependent expression of hsp60 and ICAM-1 correlates with monocyte and T-cell adhesion to aortic endothelium. These observations may be significant for elucidating the mechanism of the initiating events in the development of atherosclerosis.

Animals↗
PubMed1995

Genomic analysis of collagen and endogenous virus loci in the UCD-200 and 206 lines of chickens, animal models for scleroderma.

University of California at Davis (UCD) lines 200 and 206 chickens develop a hereditary systemic scleroderma-like connective tissue disease characterized by severe lymphocytic infiltration and excessive accumulation of collagen in skin and internal organs. The immune system seems to play an important role in the development and/or perpetuation of this condition. The main goal of our work with this strain is the investigation of interactions between endothelial cells, lymphocytes, macrophages and fibroblasts leading to the proliferation of the latter and to excessive collagen synthesis and/or deposition. One aim of the present study was to clarify whether UCD-200 and 206 chickens have a defect of collagen genes at the genomic level by means of restriction fragment length polymorphism (RFLP) analysis using non-radioactively labelled cDNA probes specific for chicken alpha 1(I), alpha 2(I), alpha 1(II), alpha 1(III), alpha 1(VI), alpha 2(VI), and alpha 3(VI) (pro) collagens. As in the human disease, no gross alteration at the genomic level of collagen genes has been found, thus providing the UCD-200/206 model to be appropriate for studying the altered collagen metabolism in systemic sclerosis (SSc). In addition to the RFLP analysis of procollagen genes, we investigated the endogenous avian leukosis virus loci (ev) of UCD-200 and 206 chickens by means of Southern blot analysis of Sac I and BamH I digested DNA samples using pRAV-2, a Rous sarcoma virus specific probe, for hybridization. Most UCD-200 and 206 chickens harbour evs 1, 3 and 10 similar to the healthy control UCD-058, but they also contain a novel ev characterized by a 4.2 kb Sac I fragment and a 6.1 kb BamH I fragment, which we would like to designate ev 23. So far, the role of ev 23 in the development of avian scleroderma is unclear; for further analysis classical crossbreeding experiments are necessary and are underway.

Alpharetrovirus↗
PubMed1995

Is atherosclerosis an immunologically mediated disease?

In contrast to general beliefs, recent data from different laboratories have provided evidence that the first stages of atherosclerosis are of an inflammatory nature. Here, Georg Wick and colleagues suggest that an autoimmune reaction against heat shock protein 60 (Hsp60), expressed by endothelial cells in areas that are subject to increased haemodynamic stress, is the initiating event in atherogenesis. Humoral and T-cell-mediated immune responses against Hsp60 have both been demonstrated early in disease. This inflammatory stage, which is reversible and has even been found in children, may progress into fully developed atherosclerotic lesions, displaying all the classical pathohistological and functional consequences, if additional risk factors such as high blood cholesterol levels, smoking and obesity, are present.

Animals↗
PubMed1995

Preferential TCR V beta 1 gene usage by autoreactive T cells in spontaneous autoimmune thyroiditis of the obese strain of chickens.

We studied T cell receptor variable beta (TCR V beta) gene usage by autoreactive T cells in spontaneous autoimmune thyroiditis (SAT) of obese strain (OS) chickens. Chicken alpha beta T cells may express either V beta 1 or V beta 2 genes, the products of which can be recognized by TCR2 and TCR3 monoclonal antibodies, respectively. Selective depletion of V beta 1+ or V beta 2+ T cells in OS chickens was accomplished by repeated injections of TCR2 or TCR3 antibodies into embryonic and 1-3-week-old chickens. The birds were killed at 20 days of age and their spleens and thyroid glands evaluated by immunohistochemistry. We found that V beta 1+ T cells preferentially infiltrated OS chicken thyroid glands. Antibody treatments resulted in a 41% reduction in frequency of V beta 1+, and a 87% reduction of the frequency of V beta 2+ cells in the circulation, and in a profound decrease of the respective T cells in spleens and thyroid glands. Selective suppression of V beta 1+ T cells partially inhibited SAT development in that thyroid-infiltrating cells and destruction of thyroid follicles were reduced by more than 50%. Thyroglobulin autoantibody serum levels were also reduced in V beta 1+ T cell-depleted OS chickens, whereas selective depletion of V beta 2+ T cells did not inhibit SAT development. These findings indicate preferential TCR V beta 1 gene usage by autoreactive T cells in SAT of OS chickens.

Animals↗
PubMed1995

Altered switch in lipid composition during T-cell blast transformation in the healthy elderly.

Decreased mitogen responsiveness of lymphocytes during aging correlates inversely with membrane microviscosity, which reflects an altered lipid composition. Therefore, we addressed the question, whether age-related alterations of lipid metabolism affect the switch in lipid composition during formation of blasts. Membrane lipids and fatty acids of peripheral blood lymphocytes from SENIEUR protocol compatible ("healthy") elderly donors (66-77 yr) and young controls (18-30 yr) were quantified after incubation with or without the mitogen phytohaemagglutinin. The blastic change in membrane lipid composition was different for young controls with respect to cholesterol, phosphatidylethanolamine, total phospholipids, as well as several fatty acids. Moreover, the age-related alterations in the switch of membrane lipids and fatty acids were significantly correlated with a decreased mitogen response. Thus, the alterations in membrane reorganization during blast formation of lymphocytes from the elderly point to a disturbed cellular lipid homeostasis with possible impact on the age-related reduction in immune function.

Adolescent↗
PubMed1995

Chronic granulomatous disease assessed by single-cell granulocyte oxidative burst activity.

Here we report on a case of chronic granulomatous disease (CGD) in a 3-year-old boy who suffered from severe repeated bacterial infections including multiple liver abscesses. The case is of interest because (1) the disease is very rare (it is the first case of CGD diagnosed at the Clinic for Pediatric Medicine, University of Innsbruck), (2) the diagnosis, based on clinical parameters and the nitrobluetetrazolium test was completed and validated by single-cell measurements of respiratory-burst activity of the patient's granulocytes in a fluorescence-activated cell sorter (FACS), and (3) the applied FACS method, adapted in our laboratory, presents one of the most sensitive and reliable methods to evaluate this aspect of disturbed granulocyte function.

Cell Separation↗
PubMed1995

Mononuclear cells isolated from fibrotic skin lesions in avian scleroderma constitutively produce fibroblast-activating cytokines and immunoglobulin M.

University of California, Davis line 200 and 206 chickens develop an inherited autoimmune fibrotic disease associated with autoantibodies and other features similar to human scleroderma. Early in life, line 200/206 chickens develop mononuclear cell (MNC) infiltrates in the skin, followed by severe dermal fibrosis and vascular occlusions. Cultured fibroblasts derived from fibrotic skin lesions of line 200/206 chickens display an activated phenotype producing elevated quantities of collagen and glycosaminoglycan (GAG) compared to fibroblasts derived from normal chicken skin. To demonstrate a link between skin mononuclear cell infiltration and fibroblast activation, we cultured MNC isolated from developing fibrotic skin lesions, normal appearing skin, and peripheral blood of line 206 chickens for 24-72 h. Subsequent assay of MNC culture supernatants for effect on the collagen and GAG production of normal chicken skin fibroblasts demonstrated that only fibrotic lesion MNC supernatants contained significant collagen and GAG synthesis stimulatory activity. Both stimulatory activities were constitutively produced, undialyzable, heat and protease sensitive, and coeluted on gel filtration with a M(r) of 24-32 kD. Gel filtration also revealed that fibrotic lesion MNC secrete a protein > 250 kD, which we have identified as immunoglobulin (Ig) M by Western blot analysis. These results demonstrate that skin infiltrating MNC secrete both fibroblast-activating cytokines and IgM and thus they likely play an important role as effector cells in the development of dermal fibrosis and autoantibodies in this avian model of scleroderma.

Animals↗
PubMed1995

In vitro allergy testing needs better standardization--test results from different laboratories lack comparability mostly due to missing effective standards.

Correct determination of specific IgE is important for the diagnosis of allergic diseases. Different detection systems are supposed to yield similar results of this standardized parameter. In order to investigate this assumption, 40 sera from allergic patients were sent in eight mailings to 23 laboratories over a 2-year period. Three IgE determinations in each serum had to be performed according to laboratory-specific methods. Whereas 'wrong' results were rare with any of the methods and the overall results to a large degree comparable, sensitivity and specificity seemed to vary considerably between antigens, methods, companies and laboratories. According to our observations, better standardization of test reagents and test methods by the suppliers is essential in order to harmonize the test results and to avoid wrong conclusions. At present, the diversity of techniques that are used for IgE determination leads to quite divergent results, and the allergist has to know that. And finally, the legislator is urged to better control these diagnostic tools, because wrong results may lead to life-threatening situations.

Evaluation Studies as Topic↗
PubMed1995

Reference intervals for human peripheral blood lymphocyte subpopulations from 'healthy' young and aged subjects.

Some lymphocyte subpopulations change during aging but age-related reference limits from a healthy reference population are still lacking. In this study, we compiled 90% reference intervals for commonly determined lymphocyte subpopulations in 'healthy' (Senieur-compatible) young (20-32 years) and elderly (65-74 years) subjects. The most striking age-related changes included increases in HLA-DR+ T lymphocytes, and the shift in the expression of CD45 isoforms from the CD45RA+CD45RO-to the CD45RA-CD45RO+ subset. Both age-related alterations occurred in the CD4+ as well as in the CD8+ subpopulations and most of them were present in the relative and absolute number of lymphocyte subsets. We compare our data with those from previous investigations on lymphocyte subpopulations from the elderly and comment on useful presentation of reference values.

Adult↗
PubMed1995

In vivo LDL receptor and HMG-CoA reductase regulation in human lymphocytes and its alterations during aging.

The LDL receptor and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase play primary roles in the regulation of cellular cholesterol metabolism. To investigate the transcriptional regulation of lipid metabolism under physiological conditions ex vivo and its alterations during aging, we analyzed both the activity and mRNA concentration of the LDL receptor and HMG-CoA reductase in freshly isolated lymphocytes from healthy young and elderly donors. Data from fluorescent reverse transcriptase-polymerase chain reaction indicated that not only plasma LDL but also plasma HDL downregulates lymphocyte LDL receptor mRNA. Downregulation by HDL was three times more effective than that by LDL and presumably involved specific HDL binding sites. There was coordinate regulation of HMG-CoA reductase mRNA with LDL receptor mRNA that was independent of plasma lipoprotein concentrations. Despite elevated plasma concentrations of LDL, lymphocytes from elderly donors paradoxically expressed increased levels of the LDL receptor (P = .030) and HMG-CoA reductase mRNA (P = .062). The age-related dysregulation of the LDL receptor was predominantly due to impaired downregulation by plasma LDL rather than by HDL. Thus, not only LDL but also HDL and age significantly influences the transcriptional regulation of the LDL receptor in extrahepatic cells in vivo.

Adult↗
PubMed1995

Autoantibodies against heat shock protein 60 mediate endothelial cytotoxicity.

Stress or heat shock proteins (hsp) are a family of approximately two dozen proteins with a high degree of amino acid sequence homology between different species, ranging from prokaryotes to humans, and are representative of a generalized response to environmental and metabolic stressors. Our previous studies showed increased expression of human hsp60 on endothelial cells of arterial intima with atherosclerotic lesions, and elevated levels of serum antibodies (Ab) against hsp65/60 in subjects with carotid atherosclerosis. To investigate the possible involvement of anti-hsp65/60 Ab in endothelial injury, specific hsp-Ab were isolated from human high titer sera by affinity chromatography and probed on heat-shock human umbilical vein endothelial cells. Purified human anti-hsp65/60 Ab reacted specifically with mycobacterial hsp65, human hsp60, and a 60-kD protein band of heat-shocked endothelial cells. High levels of hsp60 mRNA expression in endothelial cells were found between 4 and 12 h after 30 min treatment at 42 degrees C. In immunofluorescence tests, positive staining of heat-stressed endothelial cells was observed not only in the cytoplasm but also on the cell surface. Furthermore, only heat-stressed, but not untreated, Cr-labeled endothelial cells were lysed by anti-hsp65/60 Ab in the presence of complement (complement-mediated cytotoxicity) or peripheral blood mononuclear cells (antibody-dependent cellular cytotoxicity). Control Abs, including human anti-hsp65/60 low titer antiserum, human Ig fraction deprived of hsp65/60 Ab, and mAbs to Factor VIII, alpha-actin, hsp70, and CD3 showed no cytotoxic effect. In conclusion, human serum anti-hsp65 antibodies act as autoantibodies reacting with hsp60 on stressed endothelial cells and are able to mediate endothelial cytotoxicity. Thus, a humoral immune reaction to hsp60 may play an important role in the pathogenesis of atherosclerosis.

Aged↗