Biomedical subjects

M W Rolfe

Publications and source records attributed to M W Rolfe.

26 records · Page 2Linked to original sources

PubMed1992

Hard metal pneumoconiosis and the association of tumor necrosis factor-alpha.

Hard metal pneumoconiosis is a recently recognized occupational lung disease associated with the exposure to cobalt fumes in the workplace. Chronic exposure in susceptible individuals results in interstitial lung disease histopathologically manifested as interstitial fibrosis with an associated mononuclear cell infiltrate and the presence of "cannibalistic" multinucleated giant cells in the alveolar airspaces. The majority of patients present with symptoms of chronic cough and dyspnea. Interestingly, in addition, patients uniformly report significant weight loss out of proportion to their degree of respiratory impairment. In this case report we demonstrate the association of tumor necrosis factor-alpha (TNF) and hard metal (cobalt) pneumoconiosis and suggest that TNF may have a potential role in the etiology of the constitutional symptoms and the pathogenesis of interstitial lung disease.

Adult↗

PubMed1992

Regulation of human alveolar macrophage- and blood monocyte-derived interleukin-8 by prostaglandin E2 and dexamethasone.

Mononuclear phagocytes are important immune effector cells that play a fundamental role in cellular immunity. In addition to their antigen-presenting and phagocytic activities, monocytes/macrophages produce a vast array of regulatory and chemotactic cytokines. Interleukin-8 (IL-8), a potent neutrophil-activating and chemotactic peptide, is produced in large quantities by mononuclear phagocytes and may be an important mediator of local and systemic inflammatory events. In this investigation, we describe the effects of prostaglandin E2 (PGE2) and dexamethasone (Dex) on IL-8 mRNA and protein expression from lipopolysaccharide (LPS)-treated human peripheral blood monocytes (PBM) and alveolar macrophages (AM). We demonstrate the dose-dependent suppression of IL-8 from LPS-stimulated PBM by PGE2. Treatment of stimulated PBM with 10(-6) M PGE2 resulted in maximal inhibition, causing 60% suppression of both IL-8 mRNA and extracellular protein levels. In contrast, PGE2 (10(-6) to 10(-8) M) did not significantly alter IL-8 mRNA or protein expression from LPS-treated AM. Treatment of LPS-stimulated PBM and AM with Dex (10(-6) to 10(-8) M) resulted in 75% decline in IL-8 mRNA and extracellular protein from either cell population. Pretreatment of PBM with PGE2 or Dex 1 or 2 h before LPS stimulation caused a significant suppression of steady-state IL-8 mRNA levels; however, administration of either of these modulators 1 or 2 h after LPS stimulation failed to have an inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

PubMed1992

Expression and regulation of human alveolar macrophage-derived interleukin-1 receptor antagonist.

The alveolar macrophage (AM) is the sentinel immune cell of the distal airspace of the lung. These mononuclear phagocytic cells represent the major host defense against inhaled environmental agents. When activated, the AM has the capacity to release reactive oxygen and arachidonic acid metabolites and produce a number of cytokines, such as interleukin-1 (IL-1). This latter cytokine has pleiotropic effects on a variety of cells and has been implicated as one of the preeminent mediators of acute inflammation. Recently, an IL-1 receptor antagonist (IRAP) has been isolated, purified, and cloned from peripheral blood monocytes (PBM) stimulated with either adherent IgG (adhIgG) lipopolysaccharide (LPS), or phorbol myristate acetate. IRAP acts as a true receptor antagonist without agonist activity. We postulated that the AM would be a significant cellular source of IRAP from the lung. To test this hypothesis, normal human AM were immediately isolated or stimulated in a dose-dependent fashion with either LPS or adhIgG. For comparison, PBM were also isolated and treated in a similar manner. PBM expressed steady-state IRAP mRNA by Northern blot analysis only in response to LPS or adhIgG. In contrast, AM were found to express significant levels of antigenic IRAP by Western blot analysis, immunostaining, and specific ELISA, and express steady-state levels of IRAP mRNA under unstimulated culture conditions. Moreover, LPS or adhIgG failed to induce AM-derived IRAP antigen generation over unstimulated control.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchoalveolar Lavage Fluid↗

PubMed1992

Suppression of human alveolar macrophage-derived cytokines by amiloride.

Various human alveolar macrophage (AM)-derived cytokines in the lungs have been shown to be present under conditions of normal homeostasis as well as during the pathogenesis of inflammation. Although extensive investigation has demonstrated the induction of cytokines from AM, relatively little is known regarding endogenous and exogenous regulation of their production. Several pharmacologic agents, including corticosteroids, cyclooxygenase inhibitors, prostaglandins, and methyl-xanthines have been examined for their role in the modulation of mononuclear phagocyte-derived cytokines. In this study, we examine the role of amiloride for the regulation of AM-derived interleukin (IL)-8, tumor necrosis factor (TNF), IL-6, and IL-1 beta. Amiloride in concentrations of 10(-4) to 10(-6) M, concentrations capable of being achieved in the distal airways via nebulization, were shown to inhibit lipopolysaccharide-stimulated, AM-derived IL-8 and TNF in both a time- and dose-dependent fashion. In addition, 5-(N,N-hexamethylene) amiloride hydrochloride, an amiloride analogue with specific sodium channel antiport inhibition, resulted in a similar dose-dependent suppression of lipopolysaccharide-stimulated, AM-derived IL-8 production. Furthermore, the suppressive effect of amiloride appeared to be at the level of mRNA for IL-8, TNF, IL-1 beta, and IL-6, whereas steady-state levels of beta-actin mRNA remained unaltered. These findings would suggest that amiloride has a potentially important modulating influence for the regulation of AM-derived cytokines.

Amiloride↗

PubMed1992

Cytokine-induced neutrophil-derived interleukin-8.

During acute inflammation, the first line of cellular response for host defense is the neutrophil. In addition to the historic role of the neutrophil as a phagocyte, recent studies have identified this cell as an important source of a number of cytokines. In this study, we provide evidence that the neutrophil is a significant source of interleukin-8 (IL-8). Neutrophils freshly isolated from whole blood were not found to constitutively express IL-8 mRNA. In contrast, when these leukocytes were cultured on plastic they were activated, leading to the significant expression of de novo steady-state levels of IL-8 mRNA. In addition, when neutrophils were treated with cycloheximide, there was evidence for "superinduction" of steady-state levels of IL-8 mRNA and inhibition of antigenic IL-8 production. Neutrophils were subsequently stimulated with lipopolysaccharide (LPS), tumor necrosis factor-alpha, or interleukin-1-beta and were found to express IL-8 mRNA and antigen in both a time- and dose-dependent manner. Furthermore, neutrophils stimulated with traditional chemotactic/activating factors, such as the split product of the fifth component of complement (C5a), formylmethionyleucylphenylalanine (fMLP), and leukotriene B4 (LTB4) in a dose-dependent manner did not produce significant antigenic IL-8, as compared with unstimulated controls. In contrast, when neutrophils were exposed to either of these neutrophil agonists in the presence of LPS, the production of antigenic IL-8 was significantly elevated, as compared with either of the stimuli alone, suggesting a synergistic response. These data would suggest that the neutrophil can no longer be viewed as only a phagocyte or warehouse for proteolytic enzymes, but is a pivotal effector cell that is able to respond to mediators in its environment and generate cytokines. This latter neutrophil response may be important for either the elicitation of additional neutrophils or to orchestrate the conventional immune response at sites of inflammation.

Antigens↗

PubMed1991

Pulmonary fibroblast expression of interleukin-8: a model for alveolar macrophage-derived cytokine networking.

The pulmonary fibroblast's (PF) unique location allows it to communicate in a bidirectional fashion between the vascular compartment and alveolar airspace, placing it in a strategic position for the elicitation of inflammatory leukocytes into the lung. In this study, we demonstrate that PF may contribute to pulmonary inflammation through the production of a potent neutrophil chemotactic factor, interleukin (IL)-8. PF-derived IL-8 expression was dependent upon stimulation by either tumor necrosis factor (TNF) or IL-1 but not lipopolysaccharide (LPS). Both TNF and IL-1 stimulation of PF resulted in a time- and dose-dependent expression of steady-state levels of mRNA, antigen, and specific chemotactic activity consistent with IL-8. Because it was apparent that cytokine networking may exist in the lung between alveolar macrophage (AM)-derived cytokines and the production of PF-derived IL-8, we next examined an in vitro model of cellular communication within the lung. We determined that LPS-stimulated AM-conditioned media induced significant levels of PF-derived IL-8 mRNA, which was inhibited by preincubation with specific neutralizing TNF and IL-1 beta antibodies. Furthermore, when AM were directly co-cultured with PF and stimulated with LPS, the kinetic analysis of PF-derived antigenic expression of IL-8 was shifted toward the right. This suggested that PF-derived IL-8 expression in co-culture was first dependent upon activation of the AM by LPS and subsequent elaboration of macrophage inflammatory mediators. These data provide evidence that cytokine networking between AM and PF may be operative in the lung, culminating in the generation of IL-8 and elicitation of inflammatory leukocytes.

Antibodies↗

PubMed1991

Interleukin-8 gene expression from human alveolar macrophages: the role of adherence.

The human alveolar macrophage (AM) is an important immune effector cell of the lung, as this cell possesses potent antimicrobial activities and has the ability to present antigen. In addition, the Am can secrete a number of regulatory and chemotactic cytokines in response to both endogenous and exogenous stimuli. In this study, we demonstrate that the adherence of AM to plastic or cellular substrates is an important activation event leading to the gene expression of novel chemotactic cytokine interleukin (IL)-8. The culturing of AM on plastic induced the time-dependent accumulation of IL-8 mRNA. In addition, adherence of these cells induced the gene expression of the proinflammatory cytokines tumor necrosis factor-alpha and IL-1 beta. This adherence phenomenon was not specific to plastic, as AM cultured on collagen- or fibronectin-coated plates also expressed IL-8 mRNA upon adherence. The adherence of Am resulted in the induction of de novo IL-8 mRNA synthesis, as this mRNA accumulation was completely abrogated by actinomycin D. Adherence-induced IL-8 mRNA expression was not altered by cycloheximide, suggesting that de novo or ongoing protein synthesis was not required for induction of IL-8 message. Adherence of AM to plastic not only upregulated IL-8 mRNA levels but also induced the production of extracellular IL-8 immunoreactive protein. Both adherent and nonadherent AM treated with lipopolysaccharide generated substantial amounts of IL-8 mRNA. Adherence and lipopolysaccharide, however, acted in a synergistic fashion to dramatically augment the production of extracellular IL-8 from these cells. Our findings would suggest that AM adherence is an important macrophage-activating event that may play a critical role in the modulation of lung inflammatory responses.

Base Sequence↗

PubMed1991

Chemotactic cytokine (IL-8 and MCP-1) gene expression by human whole blood.

The salient features of systemic or local inflammation are the myriad of cellular and humoral interactions that result in elicitation of inflammatory leukocytes. In this study using specialized connective tissue, intact whole blood, we demonstrate the gene expression of two novel chemotactic factors. The buffy-coat cellular expression of neutrophil chemotactic/activating factor/interleukin 8 (IL-8) and monocyte chemotactic/activating protein (MCP-1) mRNA were time and dose-dependent in response to either lipopolysaccharide or zymosan stimulation. This system with the complexity of tissue provides a unique model for the determination of chemotactic cytokine gene expression.

Antigens↗