Biomedical subjects

R M Strieter

Publications and source records attributed to R M Strieter.

At least 325 records · Page 18Linked to original sources

PubMed1991

Cytokine-activated human mesangial cells generate the neutrophil chemoattractant, interleukin 8.

Human mesangial cells (MC) in culture, when stimulated by interleukin 1 alpha(IL-1 alpha) or tumour necrosis factor (TNF alpha), but not with lipopolysaccharide (LPS), express interleukin 8 (IL-8) mRNA, and both cell associated and extracellular IL-8. Dexamethasone treatment of mesangial cells induced partial inhibition of the release of extracellular IL-8, while cell-associated IL-8 and IL-8 mRNA were not significantly altered. We propose that the mesangial cell has a direct role in the initiation and propagation of inflammatory events within the glomerulus via the generation of the chemotactic cytokine IL-8.

Cells, Cultured↗

PubMed1991

Red cell ABO incompatibility and production of tumour necrosis factor-alpha.

Tumour necrosis factor-alpha (TNF) is a major mediator of diverse pathophysiological events similar to those of haemolytic transfusion reactions (HTR), such as fever, intravascular coagulation and organ failure. However, the possible role of TNF in HTR has not been investigated. We have constructed an in vitro whole blood model of HTR to examine whether TNF may be produced in red cell ABO incompatibility. TNF was observed in plasma, in a dose dependent manner, when ABO incompatible red cells were added, but not with compatible (group O) cells. Plasma TNF levels were maximal at 2 h, and declined to control levels by 24 h. Haemolysis of incompatible red cells was accompanied by TNF production. Immune haemolysis induced TNF gene expression by buffy coat leucocytes, as determined by Northern blot analysis. Heat inactivation of plasma abolished TNF production, whereas prior treatment with interferon-gamma augmented the response. These results demonstrate that a major cytokine is produced in response to red cell incompatibility, and suggest that TNF may play a role in the pathogenesis of haemolytic transfusion reactions.

ABO Blood-Group System↗

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

Elevated serum levels of tumor necrosis factor-alpha after bronchoscopy and bronchoalveolar lavage.

Fiberoptic bronchoscopy and bronchoalveolar lavage are often followed by the development of fever and other influenza-like symptoms. We report the onset of these symptoms in a healthy volunteer following bronchoscopy and bronchoalveolar lavage; the symptoms were temporally associated with the dramatic elevation of serum levels of tumor necrosis factor. Our observations suggest that tumor necrosis factor may be involved in mediating fever and other influenza-like symptoms occurring after bronchoscopy.

Bronchoalveolar Lavage Fluid↗

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↗

PubMed1991

Human corneal interleukin-8. IL-1 and TNF-induced gene expression and secretion.

Corneal leukocytic infiltration is an important component of numerous ocular diseases, but specific corneal-derived leukocyte chemotaxins have not been identified. In this study, the authors identified interleukin-8 (IL-8), a known neutrophil and lymphocyte chemotaxin, to be an important chemotaxin produced by human corneal tissue. In situ hybridization and immunohistochemistry of corneas exposed to human recombinant (r) interleukin-1-beta (rIL-1 beta) or tumor necrosis factor-alpha (rTNF-alpha) revealed significant increases in corneal endothelial and stromal cell IL-8 mRNA (P less than 0.001) and marked increases in cell-associated immunoreactive IL-8 compared with unstimulated controls. ELISA assays revealed four- to eight-fold increases in corneal IL-8 secretion after 24-hour exposures to either cytokine over that obtained with unstimulated corneas (P = 0.01). In neutrophil chemotactic bioassays, significant increases in functional IL-8 were detected in media conditioned by corneas exposed to rIL-1 beta or rTNF-alpha for 24 hours (P less than 0.001). Preincubation of these corneal media with anti-IL-8 antibody significantly reduced neutrophil chemotaxis by more than 80%. These results suggest that the cornea is an active participant in ocular inflammation and raise the possibility that agents used in experimental corneal pocket models may produce indirect effects by inducing corneal secretion of other factors, such as IL-8.

Chemotaxis, Leukocyte↗

PubMed1991

Monocyte chemotactic protein gene expression by cytokine-treated human retinal pigment epithelial cells.

Inflammation involving the retina and choroid is a common clinical problem, but the mechanisms that elicit and maintain ocular inflammation remain poorly understood. Interposed between the sensory retina and the systemic blood circulation within the choroid is the neural-derived retinal pigment epithelium (RPE), which forms part of the blood-retina barrier. The RPE is actively phagocytic and shares several features with mononuclear phagocytes of bone marrow origin, including the production of a neutrophil chemotactic factor, interleukin 8, after stimulation with interleukin 1 beta (IL-1 beta) or tumor necrosis factor alpha (TNF-alpha). Because monocyte-derived macrophages are present in retinal lesions of many common and blinding diseases, we monitored human RPE cells or monocyte chemotactic protein (MCP) mRNA expression and activity following cytokine stimulation. Cultured human RPE cells were left unstimulated or exposed to recombinant human IL-1 beta, TNF-alpha, or lipopolysaccharide. MCP mRNA expression in RPE cells and biologically active MCP in RPE cell supernatants were present 1 hour after stimulation and maintained for 24 hours. Conditioned media from RPE cells stimulated with 20 ng/ml of IL-1 beta or TNF-alpha for 24 hours contained biologically active monocyte chemotactic activity that rose rapidly from baseline levels over 4 hours and plateaued over the subsequent 20 hours. RPE chemotactic activity was dose dependent using concentrations of these cytokines ranging from 20 pg/ml to 20 ng/ml of 4-hour assays. Time- and concentration-dependent expression of RPE cell MCP mRNA was also found in the same cultures. Peak MCP mRNA expression occurred after 8 hours of stimulation with IL-1 beta or TNF-alpha. Maximal steady-state MCP mRNA expression occurred at 20 ng/ml for IL-1 beta. Immunohistochemical staining using specific anti-MCP antibodies resulted in distinctive RPE cell staining, confirming the presence of MCP in human RPE cells. These findings demonstrate that cytokine-stimulated RPE cells may evoke or augment mononuclear phagocyte-mediated ocular inflammation by synthesizing MCP.

Cells, Cultured↗

PubMed1990

Interleukin-8 production in red blood cell incompatibility.

Hemolytic transfusion reactions (HTR) are characterized by fever, shock, organ system failure, intravascular coagulation, and possibly death. The same findings may be associated with sepsis. Neutrophils have been implicated in the pathogenesis of HTR, although a mechanism for neutrophil activation has not been shown. In addition, the possible role that cytokines may play in HTR has not been investigated. We show that interleukin-8 (IL-8), a cytokine with chemotactic and neutrophil-activation properties, is produced in whole blood following addition of ABO-incompatible red blood cells, in a dose- and time-dependent manner related to the degree of hemolysis, and is inhibited by inactivation of complement. IL-8 production is accompanied by increased gene expression in the buffy coat. This observation has implications for the understanding of the pathogenesis of and for the treatment of HTR.

ABO Blood-Group System↗

PubMed1990

Human neutrophils exhibit disparate chemotactic factor gene expression.

The evolution of acute inflammation from initiation through resolution is associated with the changing character of the infiltrating leukocytes. Recruitment of these leukocytes is dependent upon the generation of chemotactic factors that have either global or specific activity for a particular leukocyte. In this manuscript we present data demonstrating that human neutrophils can express mRNA for neutrophil chemotactic factor/interleukin 8 (IL-8), but fail to express mRNA for monocyte chemotactic protein (MCP-1). The expression of IL-8 was observed upon adherence or in response to stimulation with lipopolysaccharide. Maximal IL-8 antigenic production was noted at 24 hrs. These studies demonstrate a disparate expression of chemotactic cytokines by neutrophils.

Acute Disease↗

PubMed1990

Cytokine networking in lung inflammation.

The molecules that mediate normal events in the lung also regulate the development and ultimate resolution of pulmonary inflammation. And they can orchestrate such fulminant, life-threatening disorders as septic shock. Which cytokines are involved, and how may their physiologic roles be subverted? Interleukins and tumor necrosis factor-alpha are key players.

Cytokines↗

PubMed1990

Disparate regulation of interleukin 8 gene expression from blood monocytes, endothelial cells, and fibroblasts by interleukin 4.

The role(s) of novel chemotactic cytokines as mediators in the pathogenesis of many acute and chronic disease states is becoming increasingly apparent. One of these cytokines, interleukin 8, is a product of both immune and non-immune cells. In this manuscript, we describe the suppression of IL-8 gene expression from stimulated monocytes by IL-4, while IL-4 had no suppressive effects on IL-8 gene expression from stimulated fibroblasts and endothelial cells. Our data suggest that IL-4 may function as an endogenous regulator of monocyte cytokine expression, including the chemotactic cytokine IL-8.

Chemotactic Factors↗

PubMed1990

Stimulation of alpha-adrenergic receptor augments the production of macrophage-derived tumor necrosis factor.

Accumulating evidence supports the hypothesis that neuroendocrine hormones may participate in immunologic processes. In our study we have determined that UK-14304 (UK) and norepinephrine (NE), both alpha 2-adrenergic agonists, can augment LPS-stimulated TNF from elicited macrophages (MO). The increase in TNF production was concentration dependent with an EC50 for UK and NE of 8.1 +/- 2.6 and 0.52 +/- 0.17 nM, respectively. The concentration-effect curve for UK and NE was shifted to the right by the alpha 2-antagonist yohimbine (10(-6) M), with new EC50 of 49.7 +/- 12.2 (p less than 0.001) nM and 10.3 +/- 22 nM. The augmenting effect of UK on MO TNF production was assessed over a 7 log LPS response curve. Within a single population of MO 10 nM UK shifted the LPS-induced TNF curve eightfold to the left with the greatest increase in TNF production at lower LPS concentrations. At the transcriptional level, Northern blot analysis demonstrated that UK increased LPS-induced TNF mRNA accumulation. This augmentation in TNF mRNA accumulation was blocked by yohimbine. The presence of a MO alpha-adrenergic receptor was established by demonstrating binding of the alpha 2-adrenergic antagonist 3H-yohimbine to membranes prepared from MO. This binding was rapid, saturable, reversible, and blocked by UK, clonidine, and phentolamine. These investigations support the role of alpha 2 adrenergic agonists as immunostaining compounds that may regulate cytokine production during an inflammatory response.

Animals↗

PubMed1990

IL-4 inhibits the expression of IL-8 from stimulated human monocytes.

Peripheral blood monocytes are important mediators of inflammation via the generation of various bioactive substances, including the recently isolated and cloned chemotactic peptide IL-8. Through cytokine networking, monocyte-derived cytokines are capable of inducing IL-8 expression from non-immune cells. IL-4, a B and T lymphocyte stimulatory factor, has recently been shown to inhibit monocyte/macrophage function, including the ability to suppress monocyte-generated cytokines. We describe the in vitro inhibition of IL-8 gene expression and synthesis from LPS, TNF, and IL-1 stimulated peripheral blood monocytes by IL-4. IL-4 suppressed IL-8 production from stimulated monocytes in a dose-dependent fashion, with partial suppression observed at IL-4 concentrations as low as 10 pg/ml. The IL-4-induced suppressive effects were observed even when IL-4 was administered 2 h post-LPS-stimulation. The IL-4-induced inhibition of IL-8 mRNA expression was dependent on protein synthesis, as the suppressive effects of IL-4 were significantly negated by the addition of cycloheximide. Our findings suggest that IL-4 may be an important endogenous regulator of inflammatory cell recruitment, and adds further support to the potential role of IL-4 as a down-regulator of monocyte immune function.

Base Sequence↗

PubMed1990

Cyclosporin a modulation of tumor necrosis factor gene expression and effects in vitro and in vivo.

We investigated, in vitro and in vivo, the cyclosporin A (CsA) regulation of LPS-induced TNF gene expression and subsequent pathophysiologic changes. In vitro dose-response kinetics data showed that CsA inhibited TNF bioactivity in the supernatant without delaying its production, whereas Northern blot and in situ hybridization analysis demonstrated that CsA did not inhibit TNF mRNA expression. We then sought to examine the in vivo effects of CsA (75 mg/kg) in CBA/J mice that were primed with CFA, and injected 2 wk later with LPS. CsA demonstrated suppression of local levels (ascites) of TNF as measured by either bioactivity or an anti-murine TNF ELISA. However, CsA did not decrease mRNA for TNF, or cell-associated TNF. In vivo kinetics studies were performed to show that CsA blocked both local (ascites) and systemic (plasma) LPS-induced TNF production without delaying these effects. CsA inhibited the neutrophilia and lymphopenia that developed after the LPS challenge, but did not block the lung neutrophilic infiltrate. These observations are helpful in understanding the role of the macrophage in CsA immunosuppression, particularly with regard to the ability of CsA to block LPS-induced TNF secretion.

Animals↗

PubMed1990

Pulmonary host defenses and oropharyngeal pathogens.

The lower respiratory tract is repetitively inoculated with oropharyngeal bacteria and yet pneumonia is an infrequent event. Efficient mechanisms of antibacterial defense are present in the respiratory tract that eliminate microbes before their presence or multiplication leads to disease in the majority of instances. Resident pulmonary defenses consist of aerodynamic defenses, the mucociliary apparatus, alveolar macrophages, complement, and surfactant. These resident defenses can be augmented by the development of an inflammatory response or the development of specific immunity. Significant species variability exists in the efficiency and mechanisms of clearance for oropharyngeal organisms. Streptococci are cleared promptly, Branhamella catarrhalis is cleared slowly, whereas non-typable Haemophilus influenzae multiply before being cleared. A dual phagocytic system of alveolar macrophages and recruited polymorphonuclear leukocytes is required for clearance of most oropharyngeal microbes. Systemic immunization can significantly enhance clearance of non-typable H. influenzae, suggesting immunoprophylaxis might be possible for this organism.

Animals↗

PubMed1990

Cytokine-induced gene expression of a neutrophil chemotactic factor/IL-8 in human hepatocytes.

The liver participates in inflammation via the elaboration of acute phase proteins from hepatocytes in response to IL-1, TNF-alpha, and IL-6/INF-beta 2/hepatocyte-stimulating factor. In addition, some inflammatory states of the liver are characterized by leukocyte infiltrates. Here we demonstrate that human hepatocyte lines are capable of expressing mRNA and biologic activity for a neutrophil chemotactic factor (NCF)/IL-8 in response to the inflammatory mediators IL-1 alpha, IL-1 beta, and TNF. Two human hepatoma cell lines (SK-Hep and Hep-G2) displayed a time- and dose-dependent increase in steady state levels of NCF/IL-8 mRNA and secretion of chemotactic activity in response to TNF and IL-1. Neutralizing antibody to NCF/IL-8 inhibited hepatocyte-derived chemotactic activity by 88%. In contrast to IL-1 and TNF, hepatocytes did not respond to LPS or IL-6 within the time and dose parameters used above. Although the expression of NCF/IL-8 mRNA (1.8 kb) was first detectable between 1 and 2 h poststimulation, significant chemotactic bioactivity was not observed until about 4 h. Heat-inactivated (100 degrees C, 30 min) cytokine failed to induced NCF/IL-8 mRNA synthesis, and cotreatment of cells with cytokine and cycloheximide super-induced NCF/IL-8 mRNA while inhibiting production of bioactivity. Thus, NCF/IL-8 expression is a primary induction phenomenon. Our data demonstrate the stimulus specific induction of NCF/IL-8 in hepatocytes and suggest that cytokine cell-to-cell communication circuits may be important in neutrophil-mediated inflammatory processes in the liver.

Biological Factors↗

PubMed1990

Disparate gene expression of chemotactic cytokines by human mononuclear phagocytes.

Chemotactic cytokines are becoming increasingly recognized as important participants in the coordinate recruitment of specific inflammatory cells. In this manuscript we present data demonstrating that LPS challenged human mononuclear phagocytic cells can express mRNA for neutrophil chemotactic factor/interleukin-8 (NCF/IL-8), but do not express mRNA for monocyte chemotactic protein (MCP). The expression of NCF/IL-8 mRNA was time and dose dependent. This identical stimulus response was also found in peripheral blood neutrophils. These studies demonstrate a disparate production of chemotactic cytokines by macrophages and exemplify the dynamic nature of the chemotactic response.

Base Sequence↗