PAF, cytokines, toxic oxygen products and cell injury.
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Antigen-Antibody Complex↗
Biomedical subjects
J S Warren
Publications and source records attributed to J S Warren.
Disparate roles for TNF in the pathogenesis of acute immune complex alveolitis and dermal vasculitis.
We have compared the role of tumor necrosis factor (TNF) in the pathogenesis of analogous acute immune complex-induced lung and dermal vascular injury models in rats. Intratracheal administration of IgG anti-bovine serum albumin (BSA), followed immediately by intravenous infusion of BSA, results in acute neutrophil-mediated alveolitis. Neutralization of intrapulmonary TNF activity with anti-TNF antibodies resulted in reduced pulmonary neutrophil recruitment and marked attenuation of lung injury. Intradermal injection of IgG anti-BSA, followed by intravenous BSA, results in acute neutrophil-mediated dermal vasculitis. Neither locally nor systemically administered anti-TNF antibodies reduced dermal vascular injury as measured by local hemorrhage and vasopermeability changes. Based on morphometric analysis and measurements of myeloperoxidase in tissue extracts, anti-TNF antibodies had no effect on dermal neutrophil recruitment. Intradermal and intrapulmonary administration of physiologic concentrations of recombinant human TNF resulted in modest, dose-dependent increases in local vasopermeability accompanied by negligible neutrophil recruitment. Administration of higher concentrations of TNF resulted in increases in both local vasopermeability and neutrophil recruitment. These data suggest that while both rat pulmonary and dermal blood vessels can respond to TNF-triggered proinflammatory events, endogenous TNF plays a much greater role in acute alveolitis than in dermal vasculitis.
Acute Disease↗
Modulation of keratinocyte-derived interleukin-8 which is chemotactic for neutrophils and T lymphocytes.
Interactions between T lymphocytes, neutrophils, and epidermal cells are believed to play a central role in the pathophysiology of psoriasis and other inflammatory cutaneous disorders. Although there is strong evidence that lymphocyte-function-associated antigen-1 (LFA-1) positive T cells are retained in the epidermis via intercellular adhesion molecule-1 (ICAM-1) expression induced on keratinocytes, the molecular basis for the directed migration of T cells or neutrophils towards the epidermis is not known. To investigate whether epidermal keratinocyte-derived products may be important in the migration of T cells and neutrophils into the epidermis, human keratinocytes were cultured in the presence of various cytokines and chemotactic activity of the supernatants were assessed. TNF-alpha stimulation produced directed migrational responses for both neutrophils and T-lymphocytes (both CD4 and CD8), but not B lymphocytes; 69% of T-cell movement and 80% of neutrophil migration induced by the TNF-alpha treated keratinocyte cell supernatants could be inhibited by anti-interleukin-8 (IL-8) serum. Using the same antibody, IL-8 was immunoprecipitated from the supernatants of TNF-stimulated 35S-labelled keratinocytes, and a single 7-kd band product detected by SDS-PAGE. In keeping with these biological activities and protein data, Northern blot analysis of total cellular RNA extracted from keratinocyte monolayers hybridized with a 32P-labelled 1-kb cDNA to IL-8 mRNA, revealed induction of the IL-8 gene in the presence of TNF-alpha and IL-1 beta, but not IFN-gamma. The protein kinase C agonist, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a known stimulator of psoriasiform cutaneous inflammation when applied directly to murine epidermis, strongly induced keratinocyte elaboration of IL-8 mRNA. These studies demonstrate that activated human keratinocytes are capable of producing biologically active IL-8, and provide evidence that keratinocytes can play a key role in mediating the influx of T cells and neutrophils into the epidermis.
Blotting, Northern↗
Contrasting roles for tumor necrosis factor in the pathogeneses of IgA and IgG immune complex lung injury.
Recent studies suggest that development of acute gamma G immunoglobulin (IgG) immune complex lung injury is partially dependent on a tumor necrosis factor (TNF)-dependent mechanisms of neutrophil (PMN) recruitment. The authors have sought to further define the role of intrapulmonary TNF in IgG alveolitis and to examine its role in IgA immune complex alveolitis, a neutrophil-independent model of acute lung injury. IgG immune complex lung injury resulted in a marked rise in intrapulmonary TNF activity accompanied by progressive pulmonary PMN accumulation. Intratracheal instillation of neutralizing concentrations of anti-TNF markedly reduced PMN influx measured at 4 hours but had no effect on PMN recruitment quantitated at 2 hours. IgA immune complex deposition resulted in acute lung injury accompanied by increased numbers of intrapulmonary mononuclear phagocytes but few neutrophils. Lung lavage fluids obtained from IgA immune complex-injured rats contained both neutrophil and monocyte chemotactic activities, albeit at twofold to fourfold lower concentrations than observed in IgG-mediated alveolitis. In contrast to IgG complex-mediated alveolitis, lung lavage fluids from IgA-injured rats contained no TNF activity. Intratracheal administration of anti-TNF antibodies had no effect on the development of IgA lung injury as assessed by morphology and measurements of vascular permeability. In vitro exposure of isolated alveolar macrophages to performed IgG immune complexes resulted in dose-dependent TNF secretion, while exposure to IgA complexes resulted in very low levels of TNF secretion. These data suggest that TNF-mediated pulmonary neutrophil recruitment (in IgG lung injury) is manifest chiefly in the late phase (approximately 4 hours) of developing alveolitis. The virtual absence of intrapulmonary TNF activity in evolving IgA immune complex alveolitis may in part account for the limited PMN recruitment observed in this model.
Animals↗
Role of O2- in neutrophil recruitment into sites of dermal and pulmonary vasculitis.
Using analogous models of acute dermal vasculitis and alveolitis in rats, we have examined the role of oxygen-derived metabolities in the tissue damage associated with neutrophil influx into sites of immune complex deposition. In the lung, as previously reported, catalase and deferoxamine are highly protective, while superoxide dismutase (SOD) has a transient protective effect. The xanthine oxidase inhibitors, allopurinol, and lodoxamide, are also protective. In the skin, neither catalase (which has been covalently linked to the antibody) nor deferoxamine is protective, suggesting that H2O2 and iron are not absolutely required for the development of dermal vasculitis. In the skin, SOD, as well as the inhibitors of xanthine oxidase, have protective effects. These data suggest that the neutrophil-mediated pathways of immune complex injury in the dermal and pulmonary microvascular compartments are fundamentally different. As a measurement of neutrophil accumulation, measurements of myeloperoxidase in tissue extracts have been employed. In both the lung and skin, the protective effects of SOD and the xanthine oxidase inhibitors are paralleled by reductions in neutrophil influx into sites of injury. In contrast, catalase and deferoxamine have no effect on neutrophil accumulation. These data suggest that vascular beds in rat skin and lung are fundamentally different with respect to mechanisms of acute immune complex mediated injury. The data also provide evidence that O2- contributes significantly to the accumulation of neutrophils.
Allopurinol↗
Interleukins and tumor necrosis factor in inflammation.
Intense research efforts have been directed toward characterizing mediators that control the inflammatory response and regulate the growth, differentiation, and function of cells involved in inflammation. Tumor necrosis factor, or cachectin, and members of a heterogeneous group of peptides called interleukins exhibit a wide spectrum of activities, some of which appear to influence the evolution of inflammatory processes. This review outlines the observations that have led to our current understanding of the biology of tumor necrosis factor and the interleukins. Particular attention is directed toward the evidence suggesting that these cytokines function as mediators of inflammatory responses.
Acute-Phase Reaction↗
PAF and immune complex-induced injury.
Acute immune complex-mediated dermal vasculitis and pulmonary alveolitis have been induced in rats by the intradermal injection or intrapulmonary instillation of rabbit polyclonal antibody to bovine serum albumin (BSA), followed by intravenous injection of antigen. In the dermis, using reconstitution experiments in neutrophil-depleted rats and platelet-activating factor (PAF) receptor antagonists, we have shown that accessibility of PAF receptors on neutrophils is required for the full expression of dermal vascular injury. In the lung, intratracheal instillation of PAF receptor antagonists (with anti-BSA) results in a 54% suppression of pulmonary vascular leakage, suggesting that PAF receptors are necessary for the full expression of injury. These data suggest that in immune complex-induced tissue damage in which neutrophils and their oxygen radicals and proteases play a key role, there is an interplay of PAF and neutrophils required for the full expression of injury. The possible mechanisms involved will be discussed.
Animals↗
Intrapulmonary tumor necrosis factor triggers local platelet-activating factor production in rat immune complex alveolitis.
Recent studies suggest that intrapulmonary tumor necrosis factor (TNF) participates in the pathogenesis of acute IgG immune complex alveolitis through a mechanism involving neutrophil polymorphonuclear leukocyte (PMN) recruitment. There are few in vivo studies that address mechanisms of TNF-dependent PMN recruitment and tissue injury. We have examined the relationship between intrapulmonary TNF and locally generated platelet-activating factor (PAF) in the development of acute alveolitis. Intratracheal instillation of IgG anti-bovine serum albumin followed by intravenous bovine serum albumin results in acute neutrophil-mediated alveolitis. Induction of IgG immune complex lung injury resulted in a marked increase in the whole lung and bronchoalveolar lavage PAF levels. Intratracheal instillation of the PAF antagonists, L-652,731 (Merck, Sharpe, and Dohme, Rahway, New Jersey) or WEB-2086 (Boehringer), attenuated pulmonary vascular leakage and PMN recruitment into the alveolar compartment. Neutralization of intrapulmonary TNF with anti-TNF antibodies reduced pulmonary vascular permeability, PMN recruitment, and whole lung PAF levels. Incubation of isolated mouse alveolar macrophages with recombinant murine TNF resulted in rapid (30 to 60 minutes), cell concentration-dependent PAF release. The presence of high concentrations of PAF in whole lungs obtained from PMN-depleted rats after immune complex deposition suggest that recruited PMN are not the predominant source of intrapulmonary PAF in this model. These data suggest that acute IgG immune complex alveolitis is in part mediated by TNF-triggered PAF production and that locally produced PAF promotes recruitment of PMN into the alveolar compartment.
Alveolitis, Extrinsic Allergic↗
Modification of disease by preventing free radical formation: a new concept in pharmacological intervention.
There is considerable clinical and both in vivo and in vitro experimental evidence that toxic oxygen radicals contribute to the development of tissue injury associated with the inflammatory response. There is also strong evidence that cell injury caused by activation of phagocytic cells is iron dependent. Several of the clinical studies and in vivo and in vitro experimental models supporting these conclusions and suggesting mechanisms through which iron may participate in inflammation are discussed.
Animals↗
Evidence for the role of platelet-activating factor in immune complex vasculitis in the rat.
These studies were designed to determine the role of platelet-activating factor (PAF) in the pathogenesis of immune complex (IgG) induced dermal vasculitis in the rat. In vitro, very low (pM and nM) concentrations of PAF "primed" rat neutrophils for enhanced O2-. responses to IgG immune complexes while higher concentrations were directly stimulatory. The PAF receptor antagonist, L-652,731, blocked responses (O2-. production and enzyme release) of rat neutrophils stimulated with PAF but did not block responses triggered by immune complexes, formyl chemotactic peptide or opsonized zymosan particles. When L-652,731 was added to the antibody employed in the reversed passive Arthus reaction, the injury resulting from immune complex-induced vasculitis was significantly attenuated. In order to determine if in vivo protection provided by L-652,731 was related to neutrophils, we developed a new model in which rats are systemically depleted of neutrophils by cyclophosphamide and then locally reconstituted with intact neutrophils in a manner that allows restoration of immune complex-induced vascular injury. With this model, we demonstrated that the effects of neutrophil reconstitution are substantially diminished if the cells are pretreated with L-652,731 and then washed. By priming neutrophils with substimulatory concentrations of PAF, we have also provided in vivo evidence that neutrophil priming can increase the magnitude of vascular injury. These data provide evidence that vascular injury associated with immune complex dermal vasculitis is related to availability of PAF receptors on neutrophils, suggesting a mechanism through which PAF may function as a mediator in the pathogenesis of immune complex vasculitis.
Animals↗
Tumor necrosis factor participates in the pathogenesis of acute immune complex alveolitis in the rat.
We have examined the role of intrapulmonary TNF in a rat model of acute immune complex-triggered alveolitis. Intratracheal instillation of IgG anti-bovine serum albumin (anti-BSA) followed by intravenous infusion of BSA results in acute alveolitis. Over the 4-h course of evolving lung injury, a 10-fold increase in TNF activity occurred in bronchoalveolar lavage (BAL) fluid. Immunohistochemical analysis of lung sections and BAL cells revealed that alveolar macrophages are the chief source of TNF. Antibodies that specifically neutralize rat TNF activity were raised in rabbits immunized with recombinant mouse TNF alpha. When administered into the lungs with anti-BSA, anti-TNF resulted in a marked reduction (up to 61%) in lung injury. Intratracheal instillation of exogenous TNF alone, or in combination with anti-BSA, resulted in an increase in lung injury compared to controls. Morphometric analysis and measurements of myeloperoxidase activities in whole lung extracts from rats treated with anti-TNF revealed a marked reduction in neutrophils compared to positive controls. The anti-TNF antibody preparation did not inhibit in vitro complement activation or diminish neutrophil chemotactic activity present in activated rat serum. These data indicate that intrapulmonary TNF activity is required for the full development of acute immune complex-triggered alveolitis, that alveolar macrophages are the primary source of this cytokine, and that TNF participates in the pathogenesis of immune complex alveolitis through a mechanism involving neutrophil recruitment.
Animals↗
Ultrastructural cytochemical analysis of oxygen radical-mediated immunoglobulin A immune complex induced lung injury in the rat.
Recent studies suggest that IgA immune complex induced lung injury in the rat is oxygen radical mediated. A cerium chloride (CeCl3) method was used to ultrastructurally analyze the in situ elaboration of H2O2 in IgA immune complex injured lungs. After induction of IgA immune complex lung injury, the lungs were instilled with a reaction buffer containing CeCl3 which forms an electron-dense precipitate when exposed to H2O2. Ultrastructural examination and x-ray microanalysis revealed electron-dense cerium deposits on the surfaces and in cytoplasmic vacuoles of alveolar macrophages located along damaged alveolar septae. Similar deposits were prominent on the luminal surfaces of injured pneumocytes, especially alveolar type II cells. No cerium-containing deposits were found in undamaged negative control lungs (IgA alone without antigen) or in lungs of rats that received IgA immune complexes in the presence of catalase. To further define the source of cerium-reactive products, monolayers of rat pulmonary alveolar epithelial cells were incubated with IgA complexes. Alveolar epithelial cells exposed to complexes produced no detectable H2O2 as measured by two spectrophotometric assays, and in the presence of CeCl3, exhibited negligible amounts of electron-dense material regardless of the presence or absence of catalase. The data corroborate indirect in vivo and in vitro studies which suggest that IgA immune complex induced lung injury is mediated by oxygen-derived metabolites produced by lung macrophages. Use of the CeCl3 method in intact rat lungs allows direct ultrastructural cytochemical analysis of H2O2 production in inflamed tissue.
Animals↗
Oxygen radicals, inflammation, and tissue injury.
Inflammatory reactions often result in the activation and recruitment of phagocytic cells (e.g., neutrophils and/or tissue macrophages) whose products result in injury to the tissue. In killing of endothelial cells by activated neutrophils as well as in lung injury produced by either activated neutrophils or activated macrophages there is evidence that H2O2 and iron play a role. HO. may be a key oxygen product related to the process of injury. Endothelial cells in some vascular compartments may be susceptible to neutrophil mediated injury in a manner that is independent of oxygen radicals. On the basis of in vitro observations, a synergy exits between platelets and neutrophils, resulting in enhanced oxygen radical formation by the latter. Finally, the cytokines, interleukin 1 and tumor necrosis factor, released from macrophages have both direct stimulatory effects on oxygen radical formation in neutrophils and can "prime" macrophages for enhanced oxygen radical responses to other agonists. Cytokines may also alter endothelial cells rendering them more susceptible to oxygen radical mediated injury by neutrophils. This suggests a complex network of interactions between phagocytic cells and peptide mediators, the result of which is acute, oxygen radical mediated tissue injury.
Blood Platelets↗
Macrophage-derived cytokines amplify immune complex-triggered O2-. responses by rat alveolar macrophages.
Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are monocyte macrophage-derived hormonelike regulatory proteins that participate in many physiologic and pathophysiologic processes. Several proinflammatory activities have been attributed to these cytokines, but their importance in anatomically compartmentalized inflammatory processes is unclear. The current in vitro studies have been designed to examine modulatory influences of these cytokines on O2-. responses of rat phagocytes implicated as effector cells in immune complex mediated lung injury. Purified human IL-1, recombinant human TNF (rTNF), and culture supernatant from zymosan-activated alveolar macrophages significantly amplified O2-. responses of immune complex-stimulated alveolar macrophages but did not enhance the responses of neutrophils. Equivalent concentrations of IL-1, rTNF, and alveolar macrophage culture supernatant had no direct stimulatory effect on alveolar macrophages as measured by O2-. production. Culture media from unstimulated alveolar macrophages exerted negligible effects on O2-. generation by immune complex-activated alveolar macrophages. These data indicate that O2- responses of immune complex alveolar macrophages can be enhanced by the presence of IL-1, TNF, or media from activated macrophages. It is possible that macrophage products may greatly amplify tissue injury through the enhancement of oxygen radical production.
Animals↗
Tumor necrosis factor: a plurifunctional mediator of acute inflammation.
In recent years intense research activity has been directed toward characterizing polypeptide mediators that regulate growth, differentiation, and function of cells involved in inflammation, immunity, and hematopoiesis. Tumor necrosis factor (TNF), or cachectin, is one of these cytokines. This review will summarize important observations that have led to our current definition of TNF. The relationship of TNF to other cytokines and basic TNF biology are discussed. Particular attention is directed toward the evidence which implicates TNF as an important mediator of acute inflammation.
Humans↗
Strategy to diagnose monoclonal gammopathies in serum: high-resolution electrophoresis, immunofixation, and kappa/lambda quantification.
Identification of monoclonal gammopathies in serum has involved electrophoresis of serum proteins, immunoelectrophoresis (IEP), and quantification of IgG, IgA, and IgM. Recent innovations in technology--including high-resolution electrophoresis (HRE), immunofixation (IFX), and quantification of kappa- and lambda-containing immunoglobulins--allow for more rapid and precise assessment of serum for monoclonal proteins. We present a series of guidelines to determine when high-resolution electrophoresis and quantification of immunoglobulins (including kappa and lambda) are sufficient and when additional IFX is required to characterize the monoclonal gammopathy. Of the samples studied, 88% were correctly diagnosed by HRE with quantification of immunoglobulins and kappa/lambda; only 12% required that IFX be performed. The guidelines allow us to detect monoclonal gammopathies quicker and more efficiently by avoiding redundant IEP or IFX testing. For the vast majority of cases, these guidelines allow for a correct diagnosis within one day. After one year of follow-up since completion of the study, no undetected cases of monoclonal gammopathy have eventuated.
Blood Protein Electrophoresis↗
An evaluation of a new desorption technique for air sampling sorbent tubes.
Air sampling sorbent tubes have been used for many years in determining concentrations of chemicals in the work environment. The conventional way to desorb analytes from the sorbents involves physical removal and transfer of the sorbent from the tube to a vial containing desorption solution. A new desorption technique, whole tube desorption--which involves adding the glass tube containing the sorbent to the vial containing the desorption solvents--has been evaluated. With this technique there is no transfer of sorbent out of the glass tube. Recovery efficiencies for several chemicals including ethylene oxide, methylene chloride and styrene were comparable to those obtained using traditional solvent desorption procedures. The utilization of this new desorption technique will involve a simple modification in the design of commercially available sorbent tubes so that the front and back sections can be physically separated. This new technique allows for a significant reduction in the time spent in the desorption of air sampling sorbent tubes and easier adaptation to laboratory robotic systems.
2,4-Dichlorophenoxyacetic Acid↗
Carcinoid tumor arising in a treated primary germ cell tumor of the mediastinum.
A 33-year-old man had a locally aggressive anterior mediastinal carcinoid tumor, manifested as an enlarging mass refractory to chemotherapy two years after initially successful treatment of a primary germ cell tumor. Ultrastructurally, the tumor contained dense-core endocrine-type secretory granules. Many mediastinal carcinoid tumors have been reported, but we found no examples of such a tumor arising as a sequel to or as a refractory component of a mediastinal germ cell tumor after initially effective therapy.
Adult↗