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Biomedical subjects

R N Poston

Publications and source records attributed to R N Poston.

At least 19 recordsLinked to original sources

Effect of inhaled glucocorticoids on IL-1 beta and IL-1 receptor antagonist (IL-1 ra) expression in asthmatic bronchial epithelium.

BACKGROUND: Accumulating evidence suggests that the cytokine network is central to the immunopathology of bronchial asthma and the existence of naturally occurring cytokine antagonists has added to this complexity. Upregulation of both interleukin 1 beta (IL-1 beta) and its naturally occurring receptor antagonist, interleukin 1 receptor antagonist (IL-1ra), has previously been observed on asthmatic bronchial epithelium compared with normal airways. METHODS: The effect of inhaled beclomethasone dipropionate (BDP) on asthmatic bronchial epithelial expression of IL-1 beta and IL-1ra was studied. Frozen bronchial biopsy specimens from nine asthmatic subjects receiving 1000 micrograms BDP daily for eight weeks and from six asthmatic subjects receiving matching placebo were stained with anti-IL-1 beta and anti-IL-1ra antibodies. Hue-saturation-intensity (HSI) colour image analysis was used to quantify the brown immunoperoxidase reaction colour present on the bronchial epithelium. RESULTS: There was a significant twofold decrease in the epithelial expression of IL-1 beta after treatment with BDP but no significant change was seen in IL-1ra (P = 0.175). CONCLUSION: The selective inhibition of IL-1 beta, without effect on IL-1ra, provides a novel mechanism for the anti-inflammatory action of glucocorticosteroids.

Adult

The effects of prednisolone on the cutaneous tuberculin response in patients with corticosteroid-resistant bronchial asthma.

We have used the classical tuberculin cutaneous delayed hypersensitivity immune response to investigate the effects of corticosteroids on mononuclear cell function in nine subjects with corticosteroid-resistant asthma (CRA) and six subjects with corticosteroid-sensitive asthma (CSA), who demonstrated sensitivity to intradermal purified protein derivative (PPD) of Mycobacterium tuberculosis. In a double-blind, crossover, placebo-controlled study, patients were given oral prednisolone or placebo, starting on day 0, and a predetermined intradermal dose of PPD on day 7. On day 9 the site of the induration was measured and biopsied for immunohistochemical analysis. There was no difference in skin induration between the CSA and CRA groups during the placebo arm of the study (p = 0.38). Prednisolone significantly suppressed the cutaneous induration (p, 0.003) in the CSA group but not in the CRA group. As compared with placebo, the number of macrophages (p = 0.018), eosinophils (p = 0.009), and T memory cells (p = 0.009) was suppressed by prednisolone in the CSA group but not in the CRA group. No significant suppression of the number of neutrophils or monocytes/immature macrophages was induced by prednisolone in either group. There was no difference in intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial leukocyte adhesion molecule-1 expression in blood vessels or epidermis between the CSA and CRA groups, with no suppression by prednisolone in either group. These findings suggest a defect in the responsiveness of cellular immune mechanisms to the suppressive effects of corticosteroids in steroid-resistant asthma. The differential suppressive effects of corticosteroids on cellular recruitment in the PPD response between the individuals with CSA and those with CRA are not due to modulation of expression of endothelial adhesion molecules.

Adrenal Cortex Hormones

Expression of interleukin-1 beta (IL-1beta) and interleukin-1 receptor antagonist (IL-1ra) on asthmatic bronchial epithelium.

Accumulating evidence suggests that the cytokine network is central to the immunopathology of bronchial asthma and recent findings have suggested that naturally occurring cytokine antagonists may also be involved. In this study we looked at the expression of interleukin-1 beta (IL-1beta) and its naturally occurring receptor antagonist, IL-1ra, in the normal and asthmatic bronchial wall. Frozen bronchial biopsies from 12 normal and 18 asthmatic individuals were double stained with EBM11 (a CD68 macrophage marker) and either a rabbit anti-IL-1beta or a rabbit anti-IL-1ra. Hue-saturation-intensity color image analysis (HSI) was used to quantify the brown immunoperoxidase reaction product present on the bronchial epithelium. There was an increased expression of both IL-1beta and IL-1ra in the asthmatic bronchial epithelium, p < 0.0002 and p < 0.0001, respectively. Additionally, the numbers of macrophages, of IL-1beta producing cells, and the percentage of macrophages producing IL-1beta were significantly increased in the asthmatic submucosa (p < 0.004, p < 0.002, and p < 0.008, respectively).

Adult

Localized adhesion of monocytes to human atherosclerotic plaques demonstrated in vitro: implications for atherogenesis.

Blood-derived macrophages in the arterial intima are a characteristic feature of active atherosclerotic plaques. Adherent monocytes on the luminal surface and increased adhesion molecules on the endothelium have suggested that specific molecular mechanisms are involved in monocyte/macrophage traffic into the arterial wall. Adhesion of human monocytes and related cell lines was therefore studied in vitro to histological sections of human plaques. At 37 degrees C, these cells bound selectively to the plaques. Binding to the endothelium occurred and was also present extensively in the diseased intima. Inhibition studies showed that the endothelial and general intimal binding had largely similar molecular properties. Strong inhibition was produced by antibodies to the monocyte-specific adhesion molecule CD14, to beta2 integrins, and to ICAM-1. Likewise, a peptide containing the Arg-Gly-Asp sequence was strongly inhibitory, suggesting that binding of leukocyte integrins to arterial extracellular matrix was synergistic with cell-cell interactions. A P-selectin antibody was exceptional in giving selective inhibition of endothelial adhesion, which correlates with the specific endothelial localization of this adhesion molecule. These results show that monocytes adhere to atherosclerotic plaques through the focal activation of multiple arterial wall adhesion molecules, confirming the adhesion hypothesis. A positive feedback theory for the pathogenesis of atherosclerosis can be suggested, based on the ability of macrophages in the wall to activate the endothelium, induce adhesion molecules, and facilitate additional monocyte entry. The adhesion assay provides a means for the identification of adhesion inhibitors with therapeutic potential.

Antibodies, Monoclonal

Intramuscular gold decreases cytokine expression and macrophage numbers in the rheumatoid synovial membrane.

OBJECTIVES: Cytokines, released from mononuclear cells (MNC) are mediators of joint destruction in rheumatoid arthritis (RA). The mechanisms of action of gold salts used in the treatment of RA are unknown. The aim of this study was to investigate cytokine expression and intensity of MNC infiltrate in the RA synovial membrane (SM) following treatment with sodium aurothiomalate (SAT). METHODS: Sequential blind needle biopsies were obtained at entry into the study and at two and 12 weeks after the start of SAT therapy in 10 patients with active RA. SMs were stained with a panel of monoclonal antibodies to assess cytokine expression (IL-1 alpha, IL-1 beta, TNF-alpha, IL-6, and GM-CSF). RESULTS: There was a significant decrease in IL-1 alpha, IL-1 beta, IL-6 and TNF-alpha expression 12 weeks after treatment (p < 0.004, p < 0.002, p < 0.009 and p < 0.004 respectively). This was noted in the lining layer, the perivascular aggregates and the connective tissue areas. Detailed examination of the MNC infiltrate showed a significant reduction in inflammatory monocytes (MONO) in the lining layer at two weeks (p < 0.03). A decrease in the number of CD68+ macrophages (MAC) was noted in the perivascular and connective tissue areas at 12 weeks. No significant changes were observed in the number of T and B cells and blood vessels. CONCLUSION: The results suggest that gold may suppress RA disease activity by diminishing MONO and MAC numbers and consequently monokine production in the SM.

Adult

Increased expression of the monocyte chemoattractant protein-1 in bronchial tissue from asthmatic subjects.

The expression of the monocyte chemoattractant protein (MCP-1), a member of the chemokine family of low molecular weight cytokines, was assessed by immunohistochemistry in bronchial biopsies from 12 asthmatic and 12 normal subjects. Both a monoclonal antibody (F9) and a polyclonal antibody were employed to detect MCP-1, while the mouse myeloma protein (MOPC21) was used as a negative control. Strong positive reactions for MCP-1 were seen in the bronchial epithelium. Subepithelial macrophages, blood vessels, and bronchial smooth muscle were also stained. Hue-saturation-intensity color image analysis was used to quantify reactions of the monoclonal antibody in the epithelial and subepithelial layers. With the monoclonal antibody, asthmatic biopsies showed 51.8 +/- 3.7% (mean +/- SEM) of the epithelium staining positively, whereas normal subjects reacted much less, with 6.4 +/- 1.9% of the epithelium staining (P < 0.0001); there was no overlap between the two groups. Likewise, staining was increased in the subepithelium of asthmatic airway biopsies, with 11.5 +/- 3.1% and 2.0 +/- 1.0% staining positively in asthmatic and normal subepithelium, respectively, (P < 0.002). There was a significant correlation between staining of the epithelium and subepithelium (r = 0.77, P < 0.001). The polyclonal anti-MCP-1 antibody also gave strong reactions in the epithelium and subepithelium, with 34.0 +/- 7.8% of the asthmatic and 1.6 +/- 1.0% of the normal bronchial epithelium staining positively (P < 0.0001). These increased levels of MCP-1 in the asthmatic airways suggest that they may play a role in macrophage recruitment and activation and thereby contribute to the inflammatory pathology of bronchial asthma.

Adult

Increase in the adhesion molecule P-selectin in endothelium overlying atherosclerotic plaques. Coexpression with intercellular adhesion molecule-1.

P-selectin (GMP-140) is an adhesion molecule present within endothelial cells that is rapidly translocated to the cell membrane upon activation, where it mediates endothelial-leukocyte interactions. Immunohistochemical analysis of human atherosclerotic plaques has shown strong expression of P-selectin by the endothelium overlying active atherosclerotic plaques. P-selectin is not, however, detected in normal arterial endothelium or in endothelium overlying inactive fibrous plaques. Color image analysis was used to quantitate the degree of P-selectin expression in the endothelium and demonstrates a statistically significant increase in P-selectin expression by atherosclerotic endothelial cells. Double immunofluorescence shows that some of this P-selectin is expressed on the luminal surface of the endothelial cells. Previous work has demonstrated a significant up-regulation in the expression of the intercellular adhesion molecule-1 in atherosclerotic endothelium and a study on the expression of intercellular adhesion molecule-1 and P-selectin in atherosclerosis shows a highly positive correlation. These results suggest that the selective and cooperative expression of P-selectin and intercellular adhesion molecule-1 may be involved in the recruitment of monocytes into sites of atherosclerosis.

Arteriosclerosis

Detection of GM-CSF in asthmatic bronchial epithelium and decrease by inhaled corticosteroids.

The presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) in airway epithelial cells in vivo was assessed in 15 asthmatic and 9 normal subjects. GM-CSF was analyzed using immunohistochemistry with a polyclonal and a monoclonal antibody. Hue saturation intensity color image analysis was used to quantify staining. Asthmatic airway epithelial cells stained significantly more with anti-GM-CSF than those from normal subjects (p = 0.0013 and p = 0.0003 for the polyclonal and monoclonal antibodies, respectively). Additionally, 8 asthmatic individuals inhaled 1,000 micrograms beclomethasone diproprionate per day for 8 wk and 6 asthmatic patients inhaled matching placebo. There was a significant reduction of GM-CSF in the epithelium in the patients who were given corticosteroids (p = 0.014), whereas the group of subjects who were given placebo showed no significant change in GM-CSF staining. There was a correlation between the percentage suppression of GM-CSF staining by inhaled corticosteroids and the percentage increase in FEV1 (r = 0.61, p < 0.05) and percentage decrease in carbachol responsiveness (r = 0.80, p < 0.01). These findings suggest that GM-CSF may play a role in the inflammatory processes of bronchial asthma and that the epithelial cell may be a target cell for drug action.

Administration, Inhalation

The immunohistochemical heterogeneity of atheroma macrophages: comparison with lymphoid tissues suggests that recently blood-derived macrophages can be distinguished from longer-resident cells.

We studied the antigenic markers of macrophages (Mphs) in atherosclerotic human arteries by immunohistochemistry and compared them with the patterns in Mph subpopulations of tonsil and lymph node, which are also described. The staining of atheroma intimal Mphs was assessed semiquantitatively in the subendothelial, mid, and outer intima. Three patterns of reactivity with Mph antibodies were recognized. (a) Pan-Mph (antibodies HAM56, EBM11, and CD14 group). Staining was maximal in the mid-intimal zone. (b) Subendothelial Mphs (anti-muramidase, anti-alpha-1-antitrypsin and MAC387). In lymphoid tissue, sinusoidal Mphs and a few inflammatory Mphs were stained, as well as blood monocytes. This group of antibodies recognizes Mphs that are likely to be recently blood-derived (RBD-Mphs). (c) Antibodies reactive with various histiocyte populations in lymphoid tissues (anti-Factor XIII; anti-HLA Class II and LN2) also gave maximal staining in the mid-intimal zone, but differences between lesion types suggest that they are recognizing heterogeneous subpopulations of Mphs. These observations demonstrate the heterogeneity of tissue Mphs and suggest that an insight into the dynamics of tissue Mphs can be obtained from the cell phenotype. They indicate that all stages of atherosclerosis can have an outward traffic of Mphs from the blood through the arterial intima.

Antibodies, Monoclonal

Expression of vascular cell adhesion molecule-1 in normal and inflamed synovium.

BACKGROUND: The intercellular adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) has been implicated in a number of interactions between leukocytes and cells of lymphoid and connective tissue, including endothelial cells. Such interactions within synovial tissue may be important in the pathogenesis of rheumatoid arthritis. EXPERIMENTAL DESIGN: The expression of VCAM-1 on specific cell populations in normal and inflamed synovium was investigated using a range of double-labeling techniques. RESULTS: The strongest VCAM-1 staining was found to be confined to four nonmacrophage populations (as judged in terms of CD68 expression, nonspecific esterase activity, content of prolyl hydroxylase and activity of uridine diphosphoglucose dehydrogenase): (i) type B synoviocytes, (ii) vascular wall cells outside the endothelial layer, (iii) scattered stromal cells with cytoplasmic processes, and (iv) cells resembling follicular dendritic reticulum cells in lymphoid aggregates with germinal centers (in the three samples of rheumatoid arthritic tissue where these were present). Some macrophages of the synovial intima showed weak VCAM-1 staining. Endothelial cell staining was seen but it was consistently weaker than the staining of cells of group ii. CONCLUSIONS: The four cell populations described as showing bright staining for VCAM-1 may all be involved in local interactions with leukocytes of the macrophage or lymphoid series subsequent to initial leukocyte entry into the tissue. Expression of VCAM-1 by these cells may play a role in such interactions.

Arthritis, Rheumatoid

Immunohistochemical characterization of the cellular infiltration in asthmatic bronchi.

Bronchial biopsies obtained from 16 asthmatic patients and six normal subjects were analyzed by immunohistochemistry. In the asthmatic patients, the total numbers of macrophages infiltrating the airway mucosa were increased. Many of the macrophages had the phenotypic characteristics of blood monocytes. HLA Class II antigen was expressed on infiltrating cells and airway epithelial cells. In biopsies from the asthmatics there was a significant increase in activated eosinophils, but not in neutrophils. There was also a significant increase in the numbers of T-lymphocytes in the asthmatics, but very few B-lymphocytes were detected. These results suggest that lung macrophages may have a central role to play in the mechanisms of the chronic immune-mediated inflammatory response seen in the airway mucosa of asthmatic patients.

Adult

Expression of intercellular adhesion molecule-1 in atherosclerotic plaques.

Immunohistochemistry of human atherosclerotic arteries demonstrates expression of the intercellular adhesion molecule-1 (ICAM-1) on endothelial cells, macrophages, and smooth muscle cells of the plaques. Normal arterial endothelial cells and intimal smooth muscle outside plaques give weaker or negative reactions; these differ from the strong endothelial expression in small vessels. Quantitative color-image analysis of the endothelial layer shows increased expression of ICAM-1 in all subtypes of atherosclerotic lesions, except fibrous plaques. Endothelial expression of ICAM-1 may be involved in the recruitment of monocytes to the lesion, as suggested by its role in the entry of leukocytes, including monocytes, into foci of inflammation. Collaboration with other mechanisms, particularly chemoattractant factors, may be important for this effect. ICAM-1 enhanced monocyte recruitment is a potential mechanism for the growth of an atherosclerotic plaque.

Arteries

Endothelial leukocyte adhesion molecule-1 and intercellular adhesion molecule-1 mediate the adhesion of eosinophils to endothelial cells in vitro and are expressed by endothelium in allergic cutaneous inflammation in vivo.

We have compared the adhesion of 51Cr-labeled eosinophils and neutrophils to cultured human umbilical vein endothelial cell (EC) monolayers that have been stimulated with IL-1, TNF, or LPS. Each agent stimulated the adhesion to EC of both eosinophils and neutrophils in a similar dose- and time-dependent manner. F(ab')2 fragments of mAb 1.2B6 (anti-endothelial leukocyte adhesion molecule (ELAM)-1) and mAb 6.5B5 (anti-intercellular adhesion molecule (ICAM)-1) each inhibited partially, and to a similar extent, eosinophil and neutrophil adhesion to EC monolayers prestimulated with TNF (10 ng/ml) for 6 h. Greater inhibition of both eosinophil and neutrophil adhesion was achieved by combining the effects of mAb 1.2B6 with either mAb 6.5B5 or mAb TS1/18 (anti-CD18). These observations indicate that both ELAM-1 and ICAM-1 are involved in the adhesion of eosinophils and neutrophils to EC stimulated with TNF. In order to determine whether these molecules are expressed in vivo during allergen-induced late phase allergic responses in the skin, human skin biopsies were examined at 6 h after Ag or saline challenge with the use of an alkaline phosphatase-staining technique. Both ELAM-1 and ICAM-1 were expressed with greater intensities in Ag-challenged biopsies, suggesting that these molecules may be involved in granulocyte recruitment in vivo. The similarities we have established between mechanisms of eosinophil and neutrophil adhesion to cytokine-stimulated EC suggests that factors other than differential leukocyte-EC adhesion may be responsible for the selective accumulation of eosinophils at sites of allergic inflammation.

Adult

The expression of endothelial leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in experimental cutaneous inflammation: a comparison of ultraviolet B erythema and delayed hypersensitivity.

Endothelial cell adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) are cytokine-regulated cell surface molecules involved in leukocyte adhesion. We have studied two forms of cutaneous inflammation to investigate in vivo the kinetics of adhesion molecule expression in relation to tissue accumulation of leukocytes. Immunohistology was performed on skin biopsies taken from human volunteers at 1, 6, 24, 72 h, and 1 week after two minimal erythema doses (MED) of ultraviolet B (UV-B) or intra-cutaneous tuberculin-purified protein derivative (PPD) (10-100 U). ELAM-1 expression on vascular endothelium and polymorphonuclear leukocyte infiltration were first observed at 6 h and maximal at 24 h after both UV-B and PPD. At 72 h and 1 week, however, endothelial ELAM-1 was more strongly expressed in PPD biopsies. VCAM-1 was minimally expressed in control skin, and was induced above background levels on endothelium, on some perivascular cells, and on stellate-shaped cells in the upper dermis at 24 h after injection of PPD; it was maintained up to 1 week. In contrast, no induction of VCAM-1 was seen following challenge with either 2 or 8 MED UV-B. Following PPD, but not UV-B, there was marked induction of ICAM-1 expression on basal keratinocytes. In these biopsies, the inflammation induced in response to PPD therefore differed from UV-B-induced inflammation in showing prolonged expression of endothelial ELAM-1, induction of VCAM-1 on endothelium and other cells, and induction of keratinocyte ICAM-1. These differences may result from differences in the cytokines released and may in turn be responsible for the differences in the nature of the leukocytic infiltration during the two types of inflammatory response.

Cell Adhesion

Macrophage histology in paraffin-embedded multiple sclerosis plaques is demonstrated by the monoclonal pan-macrophage marker HAM-56: correlation with chronicity of the lesion.

Using the monoclonal antibody HAM-56 with the avidin-biotin method on recent or archival paraffin-embedded tissue from multiple sclerosis brains, we have been able to distinguish between acute, chronic active and inactive lesions. HAM-56 stains all macrophages, monocytes and at least some microglia; it is the only pan-macrophage marker to our knowledge that can be satisfactorily used on conventional paraffin sections. A much narrower range of mainly perivascular macrophages in acute plaques of multiple sclerosis is stained with MAC-387, anti-muramidase and anti-alpha1-anti-trypsin. The acute plaques show HAM-56-stained macrophages throughout the lesion, and these macrophages exhibit profiles of phospholipid-rich myelinic bodies, which are also usually stainable with Luxol fast blue. Active ongoing lesions show a rim of macrophages at the edge of the lesion. These macrophages show profiles of large vacuoles, thought to represent the sudanophilic esterified cholesterol formed during demyelination. Inactive cases show none of these features; the few perivascular macrophages present often contain the end product of lipid peroxidation, ceroidlipofuscin.

Antibodies, Monoclonal