Regulation of gene expression in bacterial pathogens.
Explore the source record for details and available documents.
Erwinia↗
Biomedical subjects
T J Wilson
Publications and source records attributed to T J Wilson.
Avian scleroderma: evidence for qualitative and quantitative T cell defects.
T cell activation is dependent upon calcium influx and protein kinase C activation, with subsequent lymphocyte proliferation dependent upon IL-2. Abnormalities in T cell proliferation, including abnormal calcium influx and defective protein kinase C activation, have been identified in aged mice and humans and many autoimmune diseases including diabetes, lupus and scleroderma. Since UCD line 200 chickens, which spontaneously develop a scleroderma-like disease, have both thymic defects and a diminished peripheral blood lymphocyte response to IL-2, we have further investigated T cell function in these birds. Interestingly, line 200 T cells respond poorly in vitro to a variety of diversely acting T cell mitogens including concanavalin A, phytohemagglutinin and anti-chicken CD3 monoclonal antibody. Moreover, they do not respond well even to phorbol myristate acetate in conjunction with ionomycin. Addition of exogenous IL-2-containing supernatant concurrently with mitogenic stimulation also had no significant effect. Analysis of intracellular free calcium demonstrated that the lymphocytes from diseased birds had a reduced influx of calcium (or release for intracellular stores) following stimulation. These data clearly reflect a unique defect in T cell activation associated with avian scleroderma. Analysis of chicken CD3, CD4 and CD8 expression revealed a 39% decrease in peripheral blood CD4+ cells in scleroderma birds, although this decrease was not sufficient to explain the 80-90% decrease observed in proliferation assays and calcium influx. Our data support the hypothesis that avian scleroderma is mediated via abnormal function of lymphocyte co-stimulatory molecules or intracellular calcium regulators.
Animals↗
Cultured fibroblasts in avian scleroderma, an autoimmune fibrotic disease, display an activated phenotype.
University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma.
Animals↗
Phenotypic analysis of the chicken thymic microenvironment during ontogenic development.
The development of monoclonal antibodies (mAb) reactive with the thymic microenvironment has identified distinct subpopulations within the stromal component, but the function of these subregions in intrathymic T-cell differentiation remains essentially an enigma. In this study, we have used such a panel of mAb to examine the chicken thymus during ontogenic development to gain insight into the contributions of these thymic regions to the distinct phases of T-cell development and to further characterize the development of this organ. Our reagents have demonstrated the complex differentiation of the primitive endodermal epithelium into more specialized structures and the development of other thymic stromal components from mesectodermal cells. We also describe molecules localized to the subcapsular and perivascular regions, which have an ontogenic expression corresponding to the early localization and stimulation of thymic precursors and another molecule on the medullary vasculature expressed corresponding to the exit of mature cells from the thymus. In addition, two markers of distinct medullary epithelial clusters are initially expressed corresponding to the appearance of T-cell receptor-1 (TcR-1) and TcR-2 positive cells in the medulla, respectively. These mAb potentially represent excellent reagents for further definition of the thymic modulation of T-cell differentiation.
Age Factors↗
Phenotypic characterization of chicken thymic stromal elements.
Phenotypic profiles of the thymic stromal components provide an excellent approach to elucidating the nature of the microenvironment of this organ. To address this issue in chickens, we have produced an extensive panel of 18 mAb to the thymic stroma. These mAb have been extensively characterized with respect to their phenotypic specificities and reveal that the stromal cells are equally as complex as the T cells whose maturation they direct. They further demonstrate that, in comparison to the mammalian thymus, there is a remarkable degree of conservation in thymic architecture between phylogenetically diverse species. Eleven mAb reacted with thymic epithelial cells: MUI-73 was panepithelium, MUI-54 stained all cortical and medullary epithelium but only a minority of the subcapsule, MUI-52 was specific for isolated stellate cortical epithelial cells, MUI-62, -69, and -71 were specific for the medulla (including Hassall's corpuscle-like structures), MUI-51, -53, -70, and -75 reacted only with the type-1 epithelium, or discrete regions therein, lining the subcapsular and perivascular regions and MUI-58 demonstrated the antigenic similarity between the subcapsule and the medulla. Seven other mAb identified distinct isolated stromal cells throughout the cortex and medulla. Large thymocyte-rich regions, which often spanned from the outer cortex to medulla, lacked epithelial cells. These mAb should prove invaluable for determining the functional significance of thymic stromal-cell subsets to thymopoiesis.
Animals↗
The 14 kDa beta-galactoside binding lectin in myoblast and myotube cultures: localization by confocal microscopy.
The endogenous 14 kDa beta-galactoside-specific lectin has been localised in myoblasts and myotubes by indirect immunofluorescence using confocal microscopy. The antibodies used in these experiments suggest that in myoblast cultures the lectin is abundant on the cell surface and concentrated at ruffled edges of migrating cells. The quantity and distribution of cell surface lectin is independent of the nature of the substratum and undiminished by brief trypsinisation or lactose-washing of the cell suspension. The lectin is also abundant intracellularly, apparently relatively free in the cytoplasm until the cells approach confluency, when the lectin is concentrated into particular areas of cytoplasm resulting in a 'patchy' appearance of stained cells. After fusion to form multinucleate myotubes, intracellular lectin is less abundant and concentrated at the periphery of myotubes, from where lectin appears to be released in vesicles packed with lectin which 'bud off' from the myotube surface. In recolonising cultures, lectin is apparently more abundant and lectin-packed vesicles can also be seen 'budding off' from myoblasts. In differentiated cultures, extracellular lectin is detected both on the myotube surface and in fibrillar arrays of extracellular material.
3T3 Cells↗
Abnormalities associated with the bursal microenvironment in spontaneous dysgammaglobulinemia of UCD line 140 chickens.
UCD line 140 chickens have been previously reported to develop a syndrome of spontaneous 7s immunoglobulin deficiency and the presence of autoantibodies. Earlier studies demonstrated that these inbred birds have normal peripheral blood T and B cell numbers; they also respond normally to allogeneic stimulation. Although the 7s immunodeficiency does not manifest itself until several months of age, line 140 birds have a premature degeneration of bursa. Because of the recent development of monoclonal reagents specific for bursal elements, including surface epithelium, basement membrane associated epithelium, follicle associated epithelium, and lymphoid subpopulations, we have examined line 140 and control birds for the expression of bursal epithelial cell antigens. Line 140 birds, in contrast to control chickens, have a dramatic early alteration in the expression of an epithelial cell marker in the bursa, thymus, and intestine. Moreover, to further address this issue, we transplanted bursa from 10-day embryos onto the chorioallantoic membrane, a privileged site. Bursae from control birds became abnormal when transplanted onto line 140 CAM; they remained normal when transplanted among several control chicken lines. In contrast, line 140 bursa remained abnormal independent of the transplant procedure. Due to the marked bursal abnormality observed specific to the dysgammaglobulinemia chicken line, we propose that the microenvironmental features of line 140 bursa may predispose these birds to the development of humoral immunodeficiency and autoantibodies.
Animals↗
The effect of infectious bursal disease virus on B lymphocytes and bursal stromal components in specific pathogen-free (SPF) White Leghorn chickens.
The effect of infectious bursal disease virus (IBDV) was studied on adult specific pathogen-free (SPF) white Leghorn chickens through analysis of peripheral blood cell suspensions and histological staining patterns on various tissue types, with specific mAbs. A rapid, progressive loss of B lymphocytes was observed in the bursal cortex and medulla, peripheral blood and thymic medulla. There was, however, a resistant population of MUI-36+ cells at the bursal cortico-medullary junction and scattered around splenic periellipsoidal sheaths. These resistant cells were suggested to be a subpopulation of macrophages which expressed the MUI-36 marker; alternatively these may have phagocytosed virally infected B cells or their remnants. Throughout the period of infection, T lymphocytes appeared nonsusceptible. Further, while the distribution of stromal cell antigens within the bursal cortex remained unaltered, particular epitopes on the surface epithelium and in the medulla were lost as a consequence of viral infection. The data presented therefore suggests that immunodepression of chickens post-IBDV infection, may arise as a direct consequence of infection of B lymphocytes; additionally, it is possible that the elimination of certain crucial elements within the bursal microenvironment may contribute to this state.
Animals↗
Selective abnormalities in the thymic microenvironment associated with avian scleroderma, an inherited fibrotic disease of L200 chickens.
As a prelude to deciphering the mechanisms of intrathymic T-cell maturation we produced a panel of 18 monoclonal antibodies (mAbs) against chicken thymic stromal elements. Eleven of these detected epithelial cells. They were: pan-epithelial; subcapsule and peri-vascular (pan type 1 epithelium); subcapsular, perivascular and medulla; medulla; or cortex. Of particular interest were the sub-specificities within these regions, especially the subcapsular region. Four mAbs stained both epithelial and non-epithelial cells in discrete regions. In addition, three mAbs recognized only non-epithelial cells. One identified macrophages scattered throughout the thymus, another the connective tissue and another the medullary vascular endothelium. These reagents have provided an extensive profile of the thymic stromal architecture and revealed that these cells are equally as complex as the T cells whose differentiation they induce and regulate. While the mAbs provide a valuable means for studying the mechanisms of normal thymopoiesis, their clinical significance is unknown. UCD line 200 chickens develop an autoimmune disease manifest by dermal and internal organ fibrosis, T cell infiltrates of skin and other affected organs and production of multiple autoantibodies. We have used our panel of mAbs to evaluate the thymic microenvironment in these autoimmunity-prone chickens. A comparative analysis with control chickens revealed striking deficiencies in the L200 subcapsular regions coupled with excessive expression of MHC class II antigens, particularly in the cortex. We hypothesize that these abnormalities induce altered T-cell differentiation, thereby predisposing the L200 chickens to autoimmune disease.
Animals↗
Ontogeny of T cell development in avian scleroderma.
UCD line 200 chickens develop an inherited fibrotic disease associated with the production of antinuclear antibodies, antibodies to type II collagen, and early skin lesions characterized by intense T lymphocyte infiltrates. In the present study we have investigated the hypothesis that developmental abnormalities in T lymphocyte differentiation predispose the line 200 chickens to autoimmune disease. The status of the thymic microenvironment in these birds during ontogeny was studied with an extensive panel of monoclonal antibodies (mAbs) reactive with distinct stromal cell subsets including MHC determinants. In addition, their T-cell graft-versus-host reactivity and responses to mitogenic stimulation and interleukin (IL)-2 were also analyzed. Line 200 chickens have profound defects in thymic structure with a virtual complete absence of antigens specific for type I epithelium which lines the thymic subcapsular and perivascular regions. There are excessive levels of MHC class II positive cells, particularly in the cortex, and B cells/subset macrophages identified by mAb MUI 36. These defects are found from the late embryonic period, long before clinical disease is manifest. Furthermore, by FACS analysis, line 200 thymocytes have a major increase in IL-2 receptor density. In addition, line 200 chicken peripheral blood lymphocytes (PBL) respond poorly to mitogenic agents and have a reduced response to IL-2. Finally, it is important to note that line 200 PBL produce a normal graft-versus-host reaction. We propose that these abnormalities in T-cell differentiation are selective, not global, and may be reflective of a defect in thymic education resulting in an inappropriate response to self-antigens.
Animals↗
The ontogeny of chicken bursal stromal cells defined by monoclonal antibodies.
Molecules expressed on lymphoid stromal cells influence the differentiation of lymphocytes. We have examined the expression of stromal markers, identified by monoclonal antibodies, in the chicken bursa of Fabricius during ontogenic development. These results are also consistent with the hypothesis that medullary secretory cells are of mesenchymal origin, whereas the basement membrane-associated and some medullary epithelium are derived from the endoderm. Our results have demonstrated the complexity of bursal stromal development with determinants expressed on the adult medullary stellate cells (e.g., MUI-57 and 62) and cortical macrophages (e.g., MUI-66 and 72) detected on the early embryonic tunica propria (e.g., MUI-57, 66 and 72) or surface epithelium (e.g., MUI-62 and 66). In addition, we provide preliminary evidence regarding potential functions of these molecules in stem cell colonization (MUI-52), early B-cell differentiation (e.g., MUI-72), late bursal B-cell development (MUI-69 and 71) and the follicle-associated epithelium transport mechanism (MUI-61 and 73).
Animals↗
Phenotypic characterization of chicken bursal stromal elements.
Many, if not all, of the different phases of intrabursal B-cell maturation are controlled by the stromal components. We have used an extensive panel of mAb to provide a detailed phenotypic profile of these cells. Antigenic specificities were defined for the entire surface epithelium, interfollicular surface epithelium, follicle-associated epithelium, basement membrane, basement membrane-associated epithelium. Several mAb were specific for the medulla, including those reactive with the stellate network of epithelial cells, isolated macrophages, and granular, apparently secreted antigens. One of these, MUI-92, appears to be bursa-specific. Two mAb reacted strongly with stellate cortical macrophages, one of which weakly stained similar cells in the medulla. MHC-class II antigens were expressed on endothelium of the corticomedullary junction, macrophagelike cells in the cortex, and medulla and B lymphocytes predominantly in the cortex. Collectively, these mAb have demonstrated the antigenically distinct nature of discrete regions in the bursa, but also the continuity of the surface epithelium with the corticomedullary junction and medulla. They represent excellent reagents for defining the stromal cell contribution of B-cell development.
Animals↗
The phenotypic heterogeneity of mouse thymic stromal cells.
Sixteen monoclonal antibodies (mAb) were produced against mouse thymic stromal elements. These mAb fell into two groups of reactivity: (i) thymic epithelial markers (screened and presented according to the guidelines proposed in the 1989 Rolduc Thymic Epithelial Workshop); and (ii) non-epithelial thymic markers. Specificities of these mAb included extensive subpopulations of both epithelial and non-epithelial thymic stromal cells, as well as isolated stromal cells, demonstrating some of the complex microspecificities in existence within the thymic microenvironment. Furthermore, six of these mAb demonstrated shared antigenicity between thymocytes and thymic stromal cells, revealing greater similarities than previously recognized between these two components. Three mAb detected antigens illustrating three consecutive layers of the blood-thymus barrier: the vascular endothelium; connective tissue of the capsule and perivascular spaces; and the connective tissue associated with the basal laminae lining these regions. This study illustrates unequivocably that there are indeed complex and varied microenvironments existing within the thymus, and emphasizes the need for reclassification of these cells.
Animals↗
Cyclophosphamide- and testosterone-induced alteration in chicken bursal stroma identified by monoclonal antibodies.
Both cyclophosphamide (Cy) and testosterone propionate (TP) treatments ablate B cells in chickens. Essential bursal microenvironmental elements, however, are altered or lost following TP treatment, while bursae from Cy-injected birds can be reconstituted with donor precursors. These two models can thus be utilized to distinguish which bursal stromal molecules are functionally most important in the specific microenvironment of this organ. Monoclonal antibodies (mAb) reactive with non-lymphoid components of the chicken bursa of Fabricius have been used to examine bursal sections from birds treated with Cy or TP. Molecules have been identified on the epithelial buds and follicle-associated epithelium (FAE) that are enhanced following Cy treatment (MUI-52 and 58) and are absent in TP-treated birds. The expression of these molecules may correspond to the ability of Cy-treated but not TP-treated bursae to attract lymphoid precursors. Molecules have also been identified on cells in the subepithelial mesenchymal layer (MUI-63, 65 and 75). These cells interact with the surface epithelium (sEp) prior to epithelial bud formation, an interaction which appears to be TP sensitive. Additionally, two potentially important molecules have been identified in the bursal medulla (MUI-54 and 72) which may have an interactive role with developing B lymphocytes.
Animals↗
The sequence of the mouse 14 kDa beta-galactoside-binding lectin and evidence for its synthesis on free cytoplasmic ribosomes.
The partial amino acid sequence of the mouse 14 kDa beta-galactoside-binding lectin has been deduced from cDNA clones corresponding to 86% of the coding sequence and extending to the polyadenylation signal. The deduced amino acid sequence for the murine lectin shows 94% identity with the rat, 89% with human, 86% with bovine and 46% with the chicken 14 kDa lectins. A cDNA probe has been used to analyse genomic DNA and identify a single mRNA of approx. 570 bp in 3T3 fibroblasts, murine erythroleukaemia cells and the murine basement-membrane-secreting Engelbreth-Holm-Swarm tumour. Analysis of free and bound polyribosomes has shown that the lectin message is translated on free cytoplasmic ribosomes.
Amino Acid Sequence↗
Surgical treatment of chronic pancreatic cholangiopathy.
In a consecutive surgical series of 70 patients with chronic calcifying pancreatitis, 18 presented with fixed stenosis of the terminal common bile duct. Nine patients presented with jaundice and two had a palpable gallbladder. The most relevant laboratory datum in the series was a persistently high serum alkaline phosphatase level. Long tapering of the terminal common bile duct was the characteristic radiological sign in 45 of our patients. In five of the 18 cases compression of the terminal bile duct was due to cephalic pseudocysts. Hepaticojejunostomy-en-Y was the type of drainage chosen in 16 cases, and an end-to-side technique was used in 15 patients. Side-to-side choledochoduodenostomy was performed in two cases. In 14 patients, biliary drainage was associated with other surgical procedures on the pancreatic parenchyma. No postoperative complications due to the biliary drainage occurred in this series.
Adult↗
Response of the chicken bursal stroma to treatment with cyclophosphamide and IBD virus.
Explore the source record for details and available documents.
Animals↗