Biomedical subjects

R M Strieter

Publications and source records attributed to R M Strieter.

At least 343 records · Page 19Linked to original sources

PubMed1990

Tumor necrosis factor-alpha gene expression in human whole blood.

Tumor necrosis factor-alpha (TNF) is recognized as a principal mediator of a variety of pathophysiologic and immunologic events. Lipopolysaccharide (LPS) challenge, either in vitro or in vivo, results in significant TNF production. In this study we present data demonstrating LPS-induced TNF mRNA expression and bioactivity using an in vitro tissue system of whole blood (WB). The kinetics of LPS-induced TNF production by WB was significantly accelerated as compared to isolated cultured peripheral blood monocytes (PBM). At post-LPS challenge, plasma from WB demonstrated a rapid rise in TNF bioactivity, peaking by 4 hr (1,021 units/ml/10(6) cells), plateauing between 4 and 8 hr, and then decreasing over the next 16 hr. In contrast, the highest measured TNF bioactivity from PBM did not occur until the 24-hr time-point (175 units/ml/10(6) cells). Whole blood buffy-coat TNF mRNA was assessed by Northern blot analysis, and demonstrated significant TNF mRNA accumulation at 1 hr and a peak 2 hr post-LPS challenge. By 8 hr TNF mRNA was undetectable. Concomitant administration of LPS with either prostaglandin E2 (10(-6)M) or Dexamethasone (10(-6)M) resulted in significant suppression of LPS-induced TNF production. This data supports WB as a useful in vitro medium for the molecular and cellular analysis of TNF. As specialized connective tissue, WB may provide an important environment to study the pharmacologic manipulation of TNF mRNA and bioactivity.

Blood Physiological Phenomena↗

PubMed1990

The production of tumor necrosis factor alpha and the development of a pulmonary capillary injury following hepatic ischemia/reperfusion.

The large mass of fixed macrophages resident in the liver make it a potentially rich source of cytokines. We have previously demonstrated that an isolated and severe ischemia/reperfusion injury to the liver results in cytokine release, specifically tumor necrosis factor alpha, and that TNF is then involved in the development of pulmonary pathology. This study was designed to determine the kinetics of TNF release following varying periods of hepatic ischemia and to further investigate the acute lung injury that follows. Suprahepatic blood samples were obtained at serial time points following a 45-, 60-, 75-, or 90-min ischemic insult to a segment of the rat liver with subsequent reperfusion. Using a bioassay based on the WEHI 164 cell line, plasma TNF levels were measured in all experimental animals; sham-operated control animals had undetectable levels. Changes in pulmonary capillary permeability were then measured using a standard 125I-labeled albumin washout technique following a 90-min ischemic insult with subsequent reperfusion. A significant increase in the mean permeability index was observed 9 to 12 hr following hepatic reperfusion (.601 +/- 102 as compared with .114 +/- .085 in sham-operated controls, P less than 0.005). Animals treated with anti-TNF antiserum prior to the induction of hepatic ischemia had a significantly reduced pulmonary capillary leak compared to animals pretreated with rabbit serum without TNF-blocking properties (.184 +/- .029 versus .694 +/- 052 for the control serum, P less than 0.005). TNF release follows both moderate and severe ischemic injury to the liver and the results reported here implicate TNF as an important mediator of increased pulmonary capillary permeability. These experiments confirm previous histologic studies that demonstrated pulmonary edema and intra-alveolar hemorrhage following hepatic ischemia/reperfusion, with subsequent blockade of the histologic injury by pretreatment with anti-TNF antiserum.

Animals↗

PubMed1990

Human alveolar macrophage gene expression of interleukin-8 by tumor necrosis factor-alpha, lipopolysaccharide, and interleukin-1 beta.

The alveolar macrophage (AMO) in its pivotal position for pulmonary host defense may play a prominent role in the orchestration of polymorphonuclear leukocyte (PMN) diapedesis. We demonstrate that the human AMO may participate in these inflammatory events through the production of a novel neutrophil chemotactic factor, interleukin-8 (IL-8). The induction of AMO-derived IL-8 by tumor necrosis factor (TNF), lipopolysaccharide (LPS), and interleukin-1 (IL-1 beta) was shown to be both dose and time dependent. Maximal IL-8 gene expression, as assessed by Northern blot analyses, was achieved with 20 ng/ml and 1 microgram/ml, respectively, for each of the cytokines and LPS. A kinetic study of TNF-, IL-1 beta-, and LPS-treated AMOs showed significant steady-state IL-8 mRNA accumulation post-stimulation at 1 h, peaking by 8 h, with a decline over the next 16 h. Immunohistochemical staining using rabbit anti-human IL-8 antibody demonstrated significant immunolocalization of cell-associated IL-8 antigen at 4 h, with persistence over the next 20 h. Chemotactic bioactivity peaked by 8 h, with continued production over the next 16 h. Chemotactic bioactivity from AMO-conditioned media was inhibited by IL-8 antiserum by 2, 31, 44, and 47%, respectively, for unstimulated control, LPS-, IL-1 beta-, and TNF-treated cells. Preimmune serum had no effect on chemotactic activity. These data support the central role of the AMO in the elicitation of PMNs into the lung via the production of IL-8.

Chemotactic Factors↗

PubMed1990

Role of tumor necrosis factor-alpha in the pathophysiologic alterations after hepatic ischemia/reperfusion injury in the rat.

Cytokines are recognized as critical early mediators of organ injury. We attempted to determine whether or not severe hepatic ischemia/reperfusion injury results in tumor necrosis factor-alpha (TNF-alpha) release with subsequent local and systemic tissue injury. After 90 min of lobar hepatic ischemia, TNF was measurable during the reperfusion period in the plasma of all 14 experimental animals, with levels peaking between 9 and 352 pg/ml. Endotoxin was undetectable in the plasma of these animals. Pulmonary injury, as evidenced by a neutrophilic infiltrate, edema and intra-alveolar hemorrhage developed after hepatic reperfusion. The neutrophilic infiltrate was quantitated using a myeloperoxidase (MPO) assay; this demonstrated a significant increase in MPO after only 1 h of reperfusion. Anti-TNF antiserum pretreatment significantly reduced the pulmonary MPO after hepatic reperfusion. After a 12-h reperfusion period, there was histologic evidence of intra-alveolar hemorrhage and pulmonary edema. Morphometric assessment showed that pretreatment with anti-TNF antiserum was able to completely inhibit the development of pulmonary edema. Liver injury was quantitated by measuring serum glutamic pyruvic transaminase which showed peaks at 3 and 24 h. Anti-TNF antiserum pretreatment was able to significantly reduce both of these peak elevations. These data show that hepatic ischemia/reperfusion results in TNF production, and that this TNF is intimately associated with pulmonary and hepatic injury.

Alanine Transaminase↗

PubMed1990

Interleukin-8 gene expression by a pulmonary epithelial cell line. A model for cytokine networks in the lung.

Cellular constituents of the alveolar-capillary wall may be key participants in the recruitment of polymorphonuclear leukocytes to the lung through the generation of the novel neutrophil chemotactic peptide interleukin-8 (IL-8). This interaction appears to occur via the ability of human alveolar macrophage (AM)-derived monokines, tumor necrosis factor (TNF), and interleukin-1 (IL-1) to induce gene expression of IL-8 from pulmonary type II-like epithelial cells (A549). Northern blot analysis demonstrated that steady-state IL-8 mRNA expression, by either TNF- or IL-1 beta-treated A549 cells, occurred in both a dose- and time-dependent fashion. Similarly, extracellular antigenic IL-8, as assessed by specific ELISA, was expressed from TNF- or IL-1 beta-stimulated epithelial cells in a time-dependent fashion with maximal IL-8 antigen detected at 24 h poststimulation. Immunohistochemical staining utilizing rabbit anti-human IL-8 antibody identified immunoreactive, cell-associated IL-8 antigen as early as 8 h post-TNF or IL-1 beta stimulation. A549-generated neutrophil chemotactic bioactivity paralleled IL-8 steady-state mRNA levels. Signal specificity was demonstrated in this system as IL-8 mRNA or protein expression by lipopolysaccharide (LPS)-treated A549 cells was not different from unstimulated cells. Although LPS did not serve as a direct stimulus for the production of IL-8 by type II-like epithelial cells, the condition media from LPS-challenged AM induced a significant expression of IL-8 mRNA by the A549 cells. 24-h conditioned media from LPS-treated cells was as potent as either IL-1 beta or TNF in generating steady-state IL-8 mRNA by A549 cells. Preincubation of LPS-treated AM-conditioned media with anti-human TNF or IL-1 beta neutralizing antibodies resulted in significant abrogation of IL-8 gene expression by A549 pulmonary epithelial cells. These findings demonstrate potential cell-to-cell communication circuits that may be important between AMs and pulmonary epithelial cells during the recruitment phase of acute lung inflammation.

Blotting, Northern↗

PubMed1990

Host responses in mediating sepsis and adult respiratory distress syndrome.

Despite significant advances in intensive care unit technology and mechanical ventilatory support, mortality due to adult respiratory distress syndrome (ARDS) or multiorgan failure (MOF) has not changed significantly within the past two decades. The key to improving survival requires understanding and modifying (or eliminating) factors that may initiate (or modulate) these syndromes. Infection, and the host responses to infection, are major etiological factors responsible for the induction and perpetuation of the injury to the lung and microvasculature in ARDS and MOF, and contribute to late mortality. While the pathogenesis of ARDS and MOF-complicating sepsis remains to be elucidated, bacterially derived (eg, endotoxin or lipopolysaccharides [LPS]) and host-derived humoral and cellular mediators are of importance in both disease states. In fact, the host response to infection (or injurious stimuli) may be a more critical determinant of the outcome of sepsis and ARDS than the original inciting stimulus. The pleiotropic effects of LPS are largely indirect, and are orchestrated via its ability to trigger the release of an array of host-derived mediators of inflammation. Several potential mechanisms of injury in ARDS, sepsis, and MOF have been suggested and include a variety of inflammatory cells (neutrophils, mononuclear phagocytes, platelets), activated complement and coagulation components, vasoactive mediators (kinins, arachidonic acid metabolites, lipids, peptides), reactive oxygen radicals, and diverse cytokines. Interactions between these humoral and cellular mediators appear to set in motion an amplified cascade of events culminating in cellular and tissue injury. In this article, several of these putative inflammatory mediators are discussed in detail, and the importance of cytokine networking and the possible role of nonimmune cells in the orchestration of the inflammatory response associated with ARDS and MOF are explained. Finally, future therapeutic strategies aimed at blocking or suppressing the release or effects of endogenous mediators may be the key to improving the outcome of these disorders.

Arachidonic Acid↗

PubMed1990

Neutrophil chemotactic factor (IL-8) gene expression by cytokine-treated retinal pigment epithelial cells.

The neural-derived retinal pigment epithelium (RPE) underlies the sensory retina and is central to both retinal homeostasis and many common retinal diseases. Retinal pigment epithelium cells are actively phagocytic and share several features with macrophages that have recently been shown to produce a neutrophil chemotactic factor (NCF), also known as interleukin-8, after cytokine stimulation. Because RPE cell responses to cytokines are largely unknown, human RPE cell NCF production was monitored after interleukin-1-beta (IL-1 beta), tumor necrosis factor-alpha, or lipopolysaccharide stimulation. RPE NCF mRNA expression and RPE production of biologically active NCF was time and concentration dependent. Maximal NCF mRNA expression occurred at 20 ng/ml for IL-1 beta. Messenger RNA expression in RPE cells and biologically active NCF in RPE cell supernatants were found 1 hour after stimulation and were maintained for 24 hours. These findings demonstrate that cytokine-stimulated RPE cells may evoke or augment neutrophil-mediated inflammation by synthesizing NCF, a cytokine that may be important in ocular disease mechanisms.

Biological Assay↗

PubMed1990

Tumor necrosis factor-alpha, interleukin-8 and chemotactic cytokines.

There is little doubt that the high degree of communication observed during an immune response occurs via sophisticated cell-to-cell mediator circuits. The coordinate expression of specific signals are needed to orchestrate inflammation as the lesion is initiated, maintained, and finally resolved. Each of these phases can be viewed as a unique window of inflammation that is driven by a specific set of mediators. In this manuscript, we have developed the concept that cytokine-cytokine interactions play a prominent role in the elicitation of inflammatory cells. Our data demonstrate that the expression of chemotactic cytokines are both cell and stimulus specific. Interleukin-8, neutrophil chemotactic factor, can be synthesized by a variety of immune and non-immune cells, but the production is dependent upon an appropriate challenge. The production of monocyte chemotactic factor is much more cell restricted and appears to be generated in abundance by only non-immune cells (fibroblasts, endothelial cells, and epithelial cells). These data suggest that the recruitment of cells to a site of inflammation is dependent upon the expression of specific cytokines for both the induction and maintenance of the lesion.

Animals↗

PubMed1990

Role of tumor necrosis factor-alpha in lipopolysaccharide-induced pathologic alterations.

Tumor necrosis factor-alpha (TNF) has been implicated strongly as a principal mediator in the pathogenesis of septic shock. The authors investigated the in vivo production of TNF in CBA/J and CD-1 mice that had been primed by an intraperitoneal injection of complete Freund's adjuvant followed 2 weeks later by an intraperitoneal injection of lipopolysaccharide (LPS). TNF bioactivity peaked in both the ascites and plasma one hour after challenge, and TNF mRNA expression in the ascites cells peaked 30 minutes after LPS. After the induction of bioactivity, an interstitial pulmonary neutrophilic infiltrate occurred that was quantitated both morphometrically and by a myeloperoxidase (MPO) assay. Peripheral blood neutrophilia and lymphopenia developed after the LPS injection (PMNs: control, 46 +/- 2%; LPS, 65 +/- 3%; Lymphs control, 53 +/- 2%; LPS, 37 +/- 3%). Treatment with dexamethasone (Dex) completely inhibited the pulmonary neutrophilic infiltrate as measured by the (MPO) assay. Because Dex will inhibit the production of several cytokines, anti-TNF antiserum was given to mice at the same time as the LPS challenge to assess specifically the role of TNF in inducing these changes. This antiserum partially blocked the pulmonary neutrophil infiltrate, and completely blocked the peripheral blood changes at one hour after LPS. These data demonstrate that TNF plays an important role in the early pathophysiologic alterations that occur after systemic exposure to LPS.

Animals↗

PubMed1989

Monocyte chemotactic protein gene expression by cytokine-treated human fibroblasts and endothelial cells.

A number of cytokines are active during the evolution of an inflammatory response, including tumor necrosis factor-alpha, interleukin-1, and novel chemotactic cytokines. This latter group of mediators belong to supergene families of inflammatory signals that play a key role in the selective recruitment of immune cells. In this presentation, we present data demonstrating, for the first time, endothelial cell expression of monocyte chemotactic protein (MCP) mRNA induced by LPS, interleukin-1 or tumor necrosis factor. Human fibroblasts were also found to express monocyte chemotactic factor mRNA in response to interleukin-1 or tumor necrosis factor, but LPS was not effective. In addition, neither primary cultures expressed MCP in response to interleukin-6. These studies demonstrate that non-immune "bystander" cells can play an active role in the recruitment of inflammatory cells via the production of novel chemotactic cytokines.

Cells, Cultured↗

PubMed1989

Monokine-induced neutrophil chemotactic factor gene expression in human fibroblasts.

Although fibroblasts are important in providing a structural framework for most tissues, they also appear to be active participants in the inflammatory process via the production of specific mediators. The production of inflammatory mediators by fibroblasts is especially important in relation to their strategic location within connective tissue as they may act as a cellular communication bridge between the interstitium and vasculature. In this paper, we demonstrate that fibroblasts may participate in these inflammatory reactions by the production of a neutrophil chemotactic factor (NCF) with characteristics similar to a recently isolated and cloned monocyte-derived NCF. Either tumor necrosis factor-alpha-, interleukin-1 alpha-, or interleukin-1 beta-stimulated fibroblasts showed both a time- and dose-dependent increase in steady-state levels of NCF mRNA and secretion of chemotactic activity. In contrast, lipopolysaccharide and interleukin-6 failed to induce fibroblast-derived NCF. The expression of fibroblast-derived NCF mRNA was first detectable by 30 min poststimulation, whereas chemotactic activity was significantly observed 3-4 h postchallenge. Heat-inactivated monokine (100 degrees C) failed to induce NCF mRNA expression, suggesting that only the active proteins are capable of inducing NCF. Gel filtration analysis using high pressure liquid chromatography indicated peak chemotactic activity with an approximate molecular mass of 8000 daltons. This peak of NCF activity was found to be relatively stable to both heat and trypsin inactivation. Specificity of the fibroblast-derived neutrophil chemotactic activity was demonstrated with inhibition of chemotaxis by the addition of neutralizing antibody directed against recombinant human neutrophil chemotactic factor. These data provide evidence that monokine-treated fibroblasts can synthesize a potent chemotactic agent with molecular and physicochemical characteristics similar to monocyte-derived NCF and that this factor may contribute to neutrophil-mediated disease processes.

Base Sequence↗

PubMed1989

Cyclosporine A inhibits TNF production without decreasing TNF mRNA levels.

The role of cytokines in health and disease has received increasing attention and numerous investigations have explored the regulation of cytokine gene expression. Tumor necrosis factor-alpha (TNF) has received particular attention because of its central role in septic shock and more recent work has shown its participation in transplant immunology. We explored the mechanism of cyclosporine A (CsA) modulation of complete Freunds adjuvant macrophage (CFA-MO) TNF gene expression. From 0.001 to 1 microgram/ml, CsA dose-dependently inhibited lipopolysaccharide (LPS) induced secreted bioactivity; at doses above 10 micrograms/ml CSA was directly toxic to CFA-MO. However, there was no suppression of TNF mRNA levels, and CsA also did not inhibit the accumulation of cell-associated TNF. Thus, CsA modulates TNF gene expression in a previously undescribed manner.

Animals↗

PubMed1989

Modulation of tumor necrosis factor-alpha gene expression. Desensitization of prostaglandin E2-induced suppression.

PGE2, an immune mediator, is an inhibitor of LPS-stimulated TNF production and gene transcription. In the present study we determined whether pretreatment with PGE2 could desensitize the suppressive function of PGE2 for the production of macrophage (MO)-derived TNF. CFA-elicited MO were incubated with PGE2 or medium only, washed, and then challenged with graded doses of LPS (0.001 to 1000 ng/ml) in the presence or absence of new PGE2. The concomitant addition of PGE2 with LPS shifted the LPS concentration-effect curve 16-fold to the right with a 52% decrease in the maximum LPS response, while MO pretreated with PGE2, washed, and incubated with LPS plus new PGE2 were desensitized to TNF regulation. These latter conditions resulted in a complete loss of the ability of PGE2 to inhibit MO TNF production as demonstrated by no significant change in the EC50 of LPS. In addition, the PGE2 concentration effect curve was shifted to the right after pretreatment of MO, suggesting a desensitized PGE2 receptor system. At the transcriptional level, pretreatment of MO with PGE2 attenuated the ability of new PGE2 to inhibit LPS-dependent TNF mRNA expression. Further studies demonstrated that, although the concomitant addition of the cyclooxygenase inhibitor indomethacin plus LPS could increase TNF production, MO pretreated with indomethacin, washed, and then challenged with LPS demonstrated an inhibition of TNF expression. MO pretreated with indomethacin also demonstrated an increased sensitivity for exogenous PGE2-induced suppression of TNF mRNA and bioactivity. These investigations further support the role of PGE2 as an immunomodulating compound that may effectively regulate the local concentration of specific monokines needed to maintain an inflammatory lesion.

Adjuvants, Immunologic↗

PubMed1989

Endothelial cell gene expression of a neutrophil chemotactic factor by TNF-alpha, LPS, and IL-1 beta.

Human endothelial cells produced a neutrophil chemotactic factor (NCF) upon stimulation with tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), or lipopolysaccharide (LPS). The expression of endothelial cell-derived NCF messenger RNA and biological activity was both time- and concentration-dependent. Maximal NCF mRNA expression occurred at 10 and at 2 nanograms per milliliter for TNF and IL-1 beta, respectively; mRNA expression was first observed 1 hour after stimulation and was maintained for at least 24 hours. In situ hybridization analysis showed that NCF mRNA peaked in treated cells by 24 hours, whereas unstimulated cells were negative. These studies demonstrated that endothelial cells may participate in neutrophil-mediated inflammation by synthesizing a chemotactic factor in response to specific monokines and LPS.

Blotting, Northern↗

PubMed1989

Dynamics of dibutyryl cyclic AMP- and prostaglandin E2-mediated suppression of lipopolysaccharide-induced tumor necrosis factor alpha gene expression.

The regulation of lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF) production by prostaglandin E2 (PGE2), forskolin, and dibutyryl cyclic AMP (cAMP) was examined at the cellular and molecular levels. The above three agents could suppress LPS (100 ng/ml)-stimulated TNF production by immunologically activated murine macrophages (M phi s) in a dose-dependent manner. The concomitant addition of PGE2, dibutyryl cAMP, or forskolin to LPS-challenged M phi s resulted in 50% inhibition of TNF production at 10(-7), 3 X 10(-6), and 3 X 10(-5) M, respectively. Interestingly, delaying the addition of PGE2 or dibutyryl cAMP by 1.5 h post-LPS stimulation was also effective in suppressing the production of TNF bioactivity, but only dibutyryl cAMP was effective when its addition was delayed by 3 h. Northern (RNA) blot analysis of mRNA isolated from LPS-challenged M phi s treated with PGE2 or dibutyryl cAMP corroborated the bioactivity data. The delayed addition of PGE2 or dibutyryl cAMP by 1.5 h post-LPS stimulation resulted in a suppression of TNF mRNA accumulation by 50 to 70%. These data support the concept that LPS is a potent stimulus for M phi-derived TNF production and that this mediator is a very proximal signal in LPS-mediated disease states. Thus, therapeutic approaches that target the suppression of TNF in LPS-dependent disease states may be limited by the rapid expression of this mediator.

Adjuvants, Immunologic↗

PubMed1989

Interleukin-2-induced tumor necrosis factor-alpha (TNF-alpha) gene expression in human alveolar macrophages and blood monocytes.

Recent investigations have demonstrated interleukin-2 receptor (IL-2R) expression on both human alveolar macrophages (AM phi) and blood monocytes (PBM), but the function of these receptors has not been fully elucidated. In this study, we demonstrate that human AM phi, as well as PBM, can be induced to express biologically active TNF-alpha after challenge with interleukin-2 (IL-2). Furthermore, we examined the expression of TNF-alpha at the mRNA level via Northern blot and in situ hybridization analysis. Normal AM phi, obtained by bronchoalveolar lavage, and PBM were stimulated with either IL-2 (2,000 U/ml) or lipopolysaccharide (LPS) (10 micrograms/ml) for 18 h. Specificity was demonstrated by neutralizing TNF-alpha activity with a polyclonal rabbit anti-human TNF-alpha antibody. PBM TNF-alpha biologic activity from 11 subjects challenged with either IL-2 or LPS was 19 +/- 6 and 85 +/- 15 U/ml/10(6) cells, respectively, which represented 5-fold and 21-fold increases over control values. AM phi TNF-alpha biologic activity from nine subjects was 110 +/- 28 (IL-2-mediated) and 304 +/- 69 (LPS-mediated) U/ml/10(6) cells, which represented 2- and 6-fold increases over controls. AM phi exhibited statistically greater (p less than 0.05) TNF production in response to both IL-2 and LPS as compared to PBM. IL-2 challenge resulted in an induction of TNF-alpha mRNA accumulation, as demonstrated by Northern blot and in situ hybridization analyses. TNF-alpha mRNA was quantitated by laser densitometry for Northern blots or by counting the number of silver grains/mononuclear phagocytic cell in the in situ hybridization analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Differential regulation of tumor necrosis factor-alpha in human alveolar macrophages and peripheral blood monocytes: a cellular and molecular analysis.

Human tumor necrosis factor-alpha (TNF), a mononuclear phagocyte (MO)-derived peptide, is increasingly being recognized for its pleomorphic immunologic effects. A number of studies have demonstrated that LPS can induce TNF synthesis, but data examining the production and regulation of TNF in human MO populations are lacking. In this study, we present data demonstrating that alveolar macrophages (AMO) and peripheral blood monocytes (PBM) obtained from 10 normal volunteers display a significant difference in both the production of TNF and their susceptibility to TNF regulation by prostaglandin E2 (PGE2) and dexamethasone (Dex). Adherent populations of PBM and AMO were incubated for 18 h in the presence of either LPS (10 micrograms/ml) alone, PGE2 for 1 h prior to LPS challenge, Dex for 1 h prior to LPS challenge, or control media alone. Cell-free supernatants were examined for TNF bioactivity and cellular TNF mRNA was assessed via in situ hybridization and Northern blot analysis. PGE2 and Dex treatment of PBM suppressed LPS-induced TNF production by 78% and 72%, respectively, while AMO-TNF production was suppressed by only 22% and 33%. The accumulation of TNF mRNA in PBM was reduced 63% by PGE2 and 45% by Dex, as assessed by laser densitometry. Similar studies demonstrated that TNF mRNA accumulation in AMO was reduced 12% and 13% by PGE2 and Dex, respectively. A 1,000-fold increase in PGE2 levels was necessary to induce 50% suppression of the maximal response to AMO as compared to PBM. These data support the notion that human MO derived from different compartments or stages of differentiation exhibit differential responsiveness to immunomodulators.

Adult↗

PubMed1989

Cellular and molecular aspects of granulomatous inflammation.

Recent advances in cellular and molecular biology have provided important new avenues to assess mechanisms of granuloma formation/regulation. For example, current studies have identified various cytokines that can exert a powerful influence on both immune and non-immune cells and dictate inflammatory processes. Some of these cytokines are potentially active during the initiation and maintenance of chronic inflammation, including tumor necrosis factor, interleukin 1, and a novel class of chemotactic cytokines. This latter group of mediators belongs to a super-gene family of immune signals that play a key role in the selective recruitment of inflammatory cells to an area of inflammation. The coordinated synthesis of these cytokines is likely important to the development of the granulomatous response. The participation of molecular signals produced by non-inflammatory cells, fibroblasts, and epithelial cells, also warrants special consideration. These "bystander" cells appear to possess effector cell functions and likely serve an important role in inducing pulmonary granulomatous inflammation. Thus, a clear understanding of the cells and molecular signals involved in the initiation and maintenance of chronic pulmonary inflammation will be necessary to assess lesion development and design more selective/effective therapies.

Animals↗