GRO alpha and interleukin-8 in Pneumocystis carinii or bacterial pneumonia and adult respiratory distress syndrome

Cytokine production in an ex vivo model of SARS-CoV-2 lung infection

Introduction

The mechanisms of the SARS-CoV-2-triggered complex alterations in immune cell activation and production of cytokines in lung tissue remain poorly understood, in part because of the limited use of adequate tissue models that simulate the structure and cell composition of the lung in vivo. We developed a novel ex vivo model of SARS-CoV-2 infection of lung explants, that maintains the intact tissue composition and the viral load for up to 7-10 days. Using this model, we studied cytokine production during SARS-CoV-2 infection.

Materials and methods

Lung tissue was monitored for viability and cell composition using flow cytometry and histological analysis. SARS-CoV-2 infection was verified immunohistochemically, viral loads in tissue and culture medium were monitored by qPCR. A panel of 41 cytokines was measured in culture medium using xMAP technology.

Results

The explant lung tissue was viable and maintained viral infection that influenced the cytokine production. Elevated concentrations of G-CSF, GM-CSF, GRO-a, IFN-g, IL-6, IL-8, IP-10, MCP-3, MIP-1a, PDGF-AA, and VEGF, and decreased IL-1RA concentration were observed in infected tissue compared to non-infected tissue.

Discussion

Our results generally reflect the data obtained in COVID-19 patients. GRO-a, IFN-g, IL-6, IL-8, MCP-1, MCP-3, and RANTES correlated with the viral load, forming a distinct pro-inflammatory cluster. Thus, our lung ex vivo model faithfully reproduces some aspects of cytokine alterations in COVID-19 patients at an early disease stage, making the investigation of SARS-CoV-2 infection mechanisms more accessible and providing a potential platform for antiviral drug testing.

Leukotriene B4-induced neutrophil extracellular traps impede the clearance of Pneumocystis

Pneumocystis pneumonia (PCP) is a fungal pulmonary disease with high mortality in immunocompromised patients. Neutrophils are essential in defending against fungal infections; however, their role in PCP is controversial. Here we aim to investigate the effects of neutrophil extracellular traps (NETs) on Pneumocystis clearance and lung injury using a mouse model of PCP. Intriguingly, although neutrophils play a fundamental role in defending against fungal infections, NETs failed to eliminate Pneumocystis, but instead impaired the killing of Pneumocystis. Mechanically, Pneumocystis triggered Leukotriene B4 (LTB4)-dependent neutrophil swarming, leading to agglutinative NET formation. Blocking Leukotriene B4 with its receptor antagonist Etalocib significantly reduced the accumulation and NET release of neutrophils in vitro and in vivo, enhanced the killing ability of neutrophils against Pneumocystis, and alleviated lung injury in PCP mice. This study identifies the deleterious role of agglutinative NETs in Pneumocystis infection and reveals a new way to prevent NET formation, which provides new insights into the pathogenesis of PCP.

A Novel C-C Chemoattractant Cytokine (Chemokine) Receptor 6 (CCR6) Antagonist (PF-07054894) Distinguishes between Homologous Chemokine Receptors, Increases Basal Circulating CCR6+ T Cells, and Ameliorates Interleukin-23-Induced Skin Inflammation

Blocking chemokine receptor C-C chemoattractant cytokine (chemokine) receptor (CCR) 6-dependent T cell migration has therapeutic promise in inflammatory diseases. PF-07054894 is a novel CCR6 antagonist that blocked only CCR6, CCR7, and C-X-C chemoattractant cytokine (chemokine) receptor (CXCR) 2 in a β-arrestin assay panel of 168 G protein-coupled receptors. Inhibition of CCR6-mediated human T cell chemotaxis by (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) was insurmountable by CCR6 ligand, C-C motif ligand (CCL) 20. In contrast, blockade of CCR7-dependent chemotaxis in human T cells and CXCR2-dependent chemotaxis in human neutrophils by PF-07054894 were surmountable by CCL19 and C-X-C motif ligand 1, respectively. [3H]-PF-07054894 showed a slower dissociation rate for CCR6 than for CCR7 and CXCR2 suggesting that differences in chemotaxis patterns of inhibition could be attributable to offset kinetics. Consistent with this notion, an analog of PF-07054894 with fast dissociation rate showed surmountable inhibition of CCL20/CCR6 chemotaxis. Furthermore, pre-equilibration of T cells with PF-07054894 increased its inhibitory potency in CCL20/CCR6 chemotaxis by 10-fold. The functional selectivity of PF-07054894 for inhibition of CCR6 relative to CCR7 and CXCR2 is estimated to be at least 50- and 150-fold, respectively. When administered orally to naïve cynomolgus monkeys, PF-07054894 increased the frequency of CCR6+ peripheral blood T cells, suggesting that blockade of CCR6 inhibited homeostatic migration of T cells from blood to tissues. PF-07054894 inhibited interleukin-23-induced mouse skin ear swelling to a similar extent as genetic ablation of CCR6. PF-07054894 caused an increase in cell surface CCR6 in mouse and monkey B cells, which was recapitulated in mouse splenocytes in vitro. In conclusion, PF-07054894 is a potent and functionally selective CCR6 antagonist that blocks CCR6-mediated chemotaxis in vitro and in vivo. SIGNIFICANCE STATEMENT: The chemokine receptor, C-C chemoattractant cytokine (chemokine) receptor 6 (CCR6) plays a key role in the migration of pathogenic lymphocytes and dendritic cells into sites of inflammation. (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) is a novel CCR6 small molecule antagonist that illustrates the importance of binding kinetics in achieving pharmacological potency and selectivity. Orally administered PF-07054894 blocks homeostatic and pathogenic functions of CCR6, suggesting that it is a promising therapeutic agent for the treatment of a variety of autoimmune and inflammatory diseases.

Serum cytokine changes induced by direct hemoperfusion with polymyxin B-immobilized fiber in patients with acute respiratory failure

BACKGROUND

Polymyxin B-immobilized Fiber therapy (PMX-DHP) may improve the prognosis of patients with rapidly progressive interstitial lung diseases (ILDs). However, the mechanisms by which PMX-DHP ameliorates oxygenation are unclear. The present study aimed to clarify the changes in serum cytokine concentrations during PMX-DHP with steroid pulse therapy.

METHODS

Patients with acute respiratory failure (ARF) and rapidly progressive ILDs, acute exacerbation of idiopathic pulmonary fibrosis (IPF), or acute respiratory distress syndrome (ARDS), and treated with PMX-DHP were assessed, including patients with IPF. The serum concentrations of 38 cytokines were compared between the ARF and IPF groups before treatment. In the ARF group, cytokine levels were compared before, immediately after PMX-DHP, and the day after termination of steroid pulse therapy.

RESULTS

Fourteen ARF and eight IPF patients were enrolled. A comparison of the cytokine levels before treatment initiation revealed that EGF, GRO, IL-10, MDC, IL-12p70, IL-15, sCD40L, IL-7, IP-10, MCP-1, and MIP-1β were significantly different between the two groups. In the ARF group treated with PMX-DHP, the concentrations of MDC, IP-10, and TNF-α continuously decreased during treatment (P < 0.01). Further, the cytokine levels of GRO, IL-10, IL-1Ra, IL-5, IL-6, and MCP-1 decreased after the entire treatment period, with no change observed during the steroid-only period (P < 0.01, except GRO and MCP-1). Although PMX-DHP significantly reduced eotaxin and GM-CSF serum levels (P < 0.01 and P < 0.05), these levels did not change after treatment.

CONCLUSIONS

PMX-DHP combined with steroid pulse therapy might reduce GRO, IL-10, IL-1Ra, IL-5, IL-6, and MCP-1 levels in ARF, contributing to better oxygenation in the disorder.

Chemokines and chemokine receptors during COVID-19 infection

Chemokines are crucial inflammatory mediators needed during an immune response to clear pathogens. However, their excessive release is the main cause of hyperinflammation. In the recent COVID-19 outbreak, chemokines may be the direct cause of acute respiratory disease syndrome, a major complication leading to death in about 40% of severe cases. Several clinical investigations revealed that chemokines are directly involved in the different stages of SARS-CoV-2 infection. Here, we review the role of chemokines and their receptors in COVID-19 pathogenesis to better understand the disease immunopathology which may aid in developing possible therapeutic targets for the infection.

Time-course transcriptomic alterations reflect the pathophysiology of polyhexamethylene guanidine phosphate-induced lung injury in rats

Objective: Humidifier-disinfectant-induced lung injury is a new syndrome associated with a high mortality rate and characterized by severe hypersensitivity pneumonitis, acute interstitial pneumonia, or acute respiratory distress syndrome. Polyhexamethylene guanidine phosphate (PHMG-P), a guanidine-based antimicrobial agent, is a major component associated with severe lung injury. In-depth studies are needed to determine how PHMG-P affects pathogenesis at the molecular level. Therefore, in this study, we analyzed short-term (4 weeks) and long-term (10 weeks) PHMG-P-exposure-specific gene-expression patterns in rats to improve our understanding of time-dependent changes in fibrosis.Materials and methods: Gene-expression profiles were analyzed in rat lung tissues using DNA microarrays and bioinformatics tools.Results: Clustering analysis of gene-expression data showed different gene-alteration patterns in the short- and long-term exposure groups and higher sensitivity to gene-expression changes in the long-term exposure group than in the short-term exposure group. Supervised analysis revealed 34 short-term and 335 long-term exposure-specific genes, and functional analysis revealed that short-term exposure-specific genes were involved in PHMG-P-induced initial inflammatory responses, whereas long-term exposure-specific genes were involved in PHMG-P-related induction of chronic lung fibrosis.Conclusion: The results of transcriptomic analysis were consistent with lung histopathology results. These findings indicated that exposure-time-specific changes in gene expression closely reflected time-dependent pathological changes in PHMG-P-induced lung injury.

CXCR1/CXCR2 antagonist G31P inhibits nephritis in a mouse model of uric acid nephropathy

The prevalence of gout is relatively high worldwide, and many gout patients suffer from uric acid nephropathy (UAN) concomitantly. ELR-CXC chemokines such as CXCL8 and CXCL1 have a elevated expression in UAN. In this research, a mouse UAN model was established for a 12 week duration, and uric acid-related crystals were observed. CXCL8(3-72)K11R/G31P (G31P) is a mutant protein of CXCL8/interleukin 8 (IL-8), which has been reported to have therapeutic efficacy in both inflammatory diseases and malignancies for it acts as a selective antagonist towards CXCR1/CXCR2. In this study, G31P-treated mice showed declined production of the blood urea nitrogen (BUN) level and urine volume in UAN mice compared with G31P-untreated UAN counterparts. In addition, G31P effectively improved renal fibrosis, and reduced uric acid accumulation and leukocyte infiltration in UAN kidneys. Furthermore, the expressions of CXCL1 and CXCL2 were reduced and the activation of NOD-like receptors protein 3 (NLRP3) was inhibited by G31P treatment. This study has demonstrated that G31P attenuates inflammatory progression in chronic UAN, and plays a renoprotective function.

Severe Influenza Is Characterized by Prolonged Immune Activation: Results From the SHIVERS Cohort Study

Background

The immunologic factors underlying severe influenza are poorly understood. To address this, we compared the immune responses of influenza-confirmed hospitalized individuals with severe acute respiratory illness (SARI) to those of nonhospitalized individuals with influenza-like illness (ILI).

Methods

Peripheral blood lymphocytes were collected from 27 patients with ILI and 27 with SARI, at time of enrollment and then 2 weeks later. Innate and adaptive cellular immune responses were assessed by flow cytometry, and serum cytokine levels were assessed by a bead-based assay.

Results

During the acute phase, SARI was associated with significantly reduced numbers of circulating myeloid dendritic cells, CD192+ monocytes, and influenza virus-specific CD8+ and CD4+ T cells as compared to ILI. By the convalescent phase, however, most SARI cases displayed continued immune activation characterized by increased numbers of CD16+ monocytes and proliferating, and influenza virus-specific, CD8+ T cells as compared to ILI cases. SARI was also associated with reduced amounts of cytokines that regulate T-cell responses (ie, interleukin 4, interleukin 13, interleukin 12, interleukin 10, and tumor necrosis factor β) and hematopoiesis (interleukin 3 and granulocyte-macrophage colony-stimulating factor) but increased amounts of a proinflammatory cytokine (tumor necrosis factor α), chemotactic cytokines (MDC, MCP-1, GRO, and fractalkine), and growth-promoting cytokines (PDGFBB/AA, VEGF, and EGF) as compared to ILI.

Conclusions

Severe influenza cases showed a delay in the peripheral immune activation that likely led prolonged inflammation, compared with mild influenza cases.

The mercurial nature of neutrophils: still an enigma in ARDS?

The acute respiratory distress syndrome (ARDS) is a life-threatening lung condition resulting from direct and indirect insults to the lung. It is characterized by disruption of the endothelial-epithelial barrier, alveolar damage, pulmonary edema, and respiratory failure. A key feature of ARDS is the accumulation of neutrophils in the lung microvasculature, interstitium, and alveolar space. Despite a clear association between neutrophil influx into the lung and disease severity, there is some debate as to whether neutrophils directly contribute to disease pathogenesis. The primary function of neutrophils is to provide immediate host defense against pathogenic microorganisms. Neutrophils release numerous antimicrobial factors such as reactive oxygen species, proteinases, and neutrophil extracellular traps. However, these factors are also toxic to host cells and can result in bystander tissue damage. The excessive accumulation of neutrophils in ARDS may therefore contribute to disease progression. Central to neutrophil recruitment is the release of chemokines, including the archetypal neutrophil chemoattractant IL-8, from resident pulmonary cells. However, the chemokine network in the inflamed lung is complex and may involve several other chemokines, including CXCL10, CCL2, and CCL7. This review will therefore focus on the experimental and clinical evidence supporting neutrophils as key players in ARDS and the chemokines involved in recruiting them into the lung.

Role of chemokines in the pathogenesis of acute lung injury

Acute lung injury (ALI) is due to an uncontrolled systemic inflammatory response resulting from direct injury to the lung or indirect injury in the setting of a systemic process. Such insults lead to the systemic inflammatory response syndrome (SIRS), which includes activation of leukocytes-alveolar macrophages and sequestered neutrophils-in the lung. Although systemic inflammatory response syndrome is a physiologic response to an insult, systemic leukocyte activation, if excessive, can lead to end organ injury, such as ALI. Excessive recruitment of leukocytes is critical to the pathogenesis of ALI, and the magnitude and duration of the inflammatory process may ultimately determine the outcome in patients with ALI. Leukocyte recruitment is a well orchestrated process that depends on the function of chemokines and their receptors. Understanding the mechanisms that contribute to leukocyte recruitment in ALI may ultimately lead to the development of effective therapeutic strategies.

Immunosuppression following surgical and traumatic injury

Severe sepsis and organ failure are still the major causes of postoperative morbidity and mortality after major hepatobiliary pancreatic surgery. Despite recent progress in understanding the immune conditions of abdominal sepsis, the postoperative incidence of septic complications after major visceral surgery remains high. This review focuses on the clinical and immunological parameters that determine the risk of the development and lethal outcome of postoperative septic complication following major surgery and trauma. A review of the literature indicates that surgical and traumatic injury profoundly affects the innate and adaptive immune responses, and that a marked suppression in cell-mediated immunity following an excessive inflammatory response appears to be responsible for the increased susceptibility to subsequent sepsis. The innate and adaptive immune responses are initiated and modulated by pathogen-associated molecular-pattern molecules and by damage-associated molecular-pattern molecules through the pattern-recognition receptors. Suppression of cell-mediated immunity may be caused by multifaceted cytokine/inhibitor profiles in the circulation and other compartments of the host, excessive activation and dysregulated recruitment of polymorphonuclear neutrophils, induction of alternatively activated or regulatory macrophages that have anti-inflammatory properties, a shift in the T-helper (Th)1/Th2 balance toward Th2, appearance of regulatory T cells, which are potent suppressors of the innate and adaptive immune system, and lymphocyte apoptosis in patients with sepsis. Recent basic and clinical studies have elucidated the functional effects of surgical and traumatic injury on the immune system. The research studies of interest may in future aid in the selection of appropriate therapeutic protocols.

Protection against sepsis-induced lung injury by selective inhibition of protein kinase C-δ (δ-PKC)

Inflammation and proinflammatory mediators are activators of δ-PKC. In vitro, δ-PKC regulates proinflammatory signaling in neutrophils and endothelial and epithelial cells, cells that can contribute to lung tissue damage associated with inflammation. In this study, a specific δ-PKC TAT peptide inhibitor was used to test the hypothesis that inhibition of δ-PKC would attenuate lung injury in an animal model of ARDS. Experimental ARDS was induced in rats via 2CLP, a model of polymicrobial sepsis. Following 2CLP surgery, the δ-PKC TAT inhibitory peptide (2CLP+δ-PKC TAT in PBS) or PBS (2CLP+PBS) was administered intratracheally. Controls consisted of SO, where animals underwent a laparotomy without 2CLP. Twenty-four hours after SO or 2CLP, blood, BALF, and lung tissue were collected. 2CLP induced δ-PKC phosphorylation in the lung within 24 h. Treatment with the δ-PKC TAT inhibitory peptide significantly decreased pulmonary δ-PKC phosphorylation, indicating effective inhibition of δ-PKC activation. Plasma and BALF levels of the chemokines CINC-1 and MIP-2 were elevated in 2CLP + PBS rats as compared with SO rats. Treatment with δ-PKC TAT reduced 2CLP-induced elevations in chemokine levels in BALF and plasma, suggesting that δ-PKC modulated chemokine expression. Most importantly, intratracheal administration of δ-PKC TAT peptide significantly attenuated inflammatory cell infiltration, disruption of lung architecture, and pulmonary edema associated with 2CLP. Thus, δ-PKC is an important regulator of proinflammatory events in the lung. Targeted inhibition of δ-PKC exerted a lung-protective effect 24 h after 2CLP.

Measurement of soluble inflammatory mediators in cerebrospinal fluid of human immunodeficiency virus-positive patients at distinct stages of infection by solid-phase protein array

The objective of this study was to evaluate immune cytokine expression in cerebrospinal fluid (CSF) of patients with human immunodeficiency virus-1 (HIV-1)-associated dementia (HAD) using a novel cytokine array assay. HIV-1 induces a condition resembling classical subcortical dementia, known as HAD. The immune mechanisms contributing to HAD have not been elucidated. Cytokine expression in CSF was determined by solid-phase protein array in 33 neurologically asymptomatic HIV-positive male patients and were compared to levels in non-HIV controls and patients with HAD. Neurological examinations and lumbar and venous punctures were conducted in all patients and controls. Interleukin (IL)-1, IL-4, and IL-10, were up-regulated in all treated acquired immunodeficiency syndrome (AIDS) patients independent of neurological status compared to controls. In contrast, interferon gamma (IFN-gamma), IL-1alpha, IL-15, and tumor necrosis factor alpha (TNF-alpha) were highly expressed in patients with HAD compared to undemented HIV-positive patients. These results show that solid-phase protein array can detect immunological changes in patients infected with HIV. Cytokine expression levels differ in different disease stages and in patients on different treatment paradigms. Pending further validation on a larger number of patients, this method may be a useful tool in CSF diagnostics and the longitudinal evaluation of patient with HAD.

Dysregulated macrophage-inflammatory protein-2 expression drives illness in bacterial superinfection of influenza

Influenza virus infection is a leading cause of death and disability throughout the world. Influenza-infected hosts are vulnerable to secondary bacterial infection, however, and an ensuing bacterial pneumonia is actually the predominant cause of influenza-attributed deaths during pandemics. A number of mechanisms have been proposed by which influenza may predispose to superinfection with an unrelated or heterologous pathogen, but the subsequent interaction between the host, virus, and bacteria remains an understudied area. In this study, we develop and examine a novel model of heterologous pulmonary infection in which an otherwise subclinical Bordetella parapertussis infection synergizes with an influenza virus infection to yield a life-threatening secondary pneumonia. Despite a profound pulmonary inflammatory response and unaltered viral clearance, bacterial clearance was significantly impaired in heterologously infected mice. No deficits were observed in pulmonary or systemic adaptive immune responses or the viability or function of infiltrating inflammatory cells to explain this phenomenon, and we provide evidence that the onset of severe pulmonary inflammation actually precedes the increased bacterial burden, suggesting that exacerbated inflammation is independent of bacterial burden. To that end, neutralization of the ELR(+) inflammatory chemokine MIP-2 (CXCL2/GRO-beta) attenuated the inflammation, weight loss, and clinical presentation of heterologously infected mice without impacting bacterial burden. These data suggest that pulmonary inflammation, rather than pathogen burden, is the key threat during bacterial superinfection of influenza and that selective chemokine antagonists may be a novel therapeutic intervention in cases of bacterial superinfection of influenza.

The absence of Hck, Fgr, and Lyn tyrosine kinases augments lung innate immune responses to Pneumocystis murina

Src family tyrosine kinases (SFKs) phosphorylate immunotyrosine activation motifs in the cytoplasmic tail of multiple immunoreceptors, leading to the initiation of cellular effector functions, such as phagocytosis, reactive oxygen species production, and cytokine production. SFKs also play important roles in regulating these responses through the activation of immunotyrosine inhibitory motif-containing inhibitory receptors. As myeloid cells preferentially express the SFKs Hck, Fgr, and Lyn, we questioned the role of these kinases in innate immune responses to Pneumocystis murina. Increased phosphorylation of Hck was readily detectable in alveolar macrophages after stimulation with P. murina. We further observed decreased phosphorylation of Lyn on its C-terminal inhibitory tyrosine in P. murina-stimulated alveolar macrophages, indicating that SFKs were activated in alveolar macrophages in response to P. murina. Mice deficient in Hck, Fgr, and Lyn exhibited augmented clearance 3 and 7 days after intratracheal administration of P. murina, which correlated with elevated levels of interleukin 1beta (IL-1beta), IL-6, CXCL1/KC, CCL2/monocyte chemoattractant protein 1, and granulocyte colony-stimulating factor in lung homogenates and a dramatic increase in macrophage and neutrophil recruitment. Augmented P. murina clearance was also observed in Lyn(-/-) mice 3 days postchallenge, although the level was less than that observed in Hck(-/-) Fgr(-/-) Lyn(-/-) mice. A correlate to augmented clearance of P. murina in Hck(-/-) Fgr(-/-) Lyn(-/-) mice was a greater ability of alveolar macrophages from these mice to kill P. murina in vitro, suggesting that SFKs regulate the alveolar macrophage effector function against P. murina. Mice deficient in paired immunoglobulin receptor B (PIR-B), an inhibitory receptor activated by SFKs, did not exhibit enhanced inflammatory responsiveness to or clearance of P. murina. Our results suggest that SFKs regulate innate lung responses to P. murina in a PIR-B-independent manner.

Evaluation of bronchoalveolar lavage fluid from ARDS patients with regard to apoptosis

BACKGROUND

Apoptosis is thought to play an important role in the development of acute respiratory distress syndrome (ARDS). We evaluated the bronchoalveolar lavage (BAL) fluid from ARDS patients focusing on apoptosis.

METHODS

The study enrolled 31 ARDS patients and 20 healthy controls. BAL fluid levels of caspase-cleaved cytokeratin-18 (CK-18) and soluble mediators such as interleukin-8 (IL-8), soluble Fas (sFas), soluble Fas ligand (sFasL), growth-related oncogene-alpha (GRO-alpha), granulocyte colony-stimulating factor (G-CSF), and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The BAL fluid caspase-cleaved CK-18 levels in ARDS patients were higher than those in controls, reflecting increased epithelial apoptosis, and were correlated with lung injury scores (rs=0.49). The BAL fluid levels of all mediators were significantly higher in ARDS patients than in controls. In ARDS patients, the BAL fluid IL-8 level was positively correlated with the levels of sFas (rs=0.57), GRO-alpha (rs=0.47), and TRAIL (rs=0.45). The BAL fluid IL-8 (rs=0.61), sFas (rs=0.57), G-CSF (rs=0.44), and TRAIL (rs=0.33) levels were correlated with the BAL fluid neutrophil count. The G-CSF levels were significantly higher in non-surviving than in surviving ARDS patients [median 183.4 pg/mL (interquartile range 76.7-315.9) vs. 63.8 pg/mL (36.2-137.2); p<0.05]. The sFas levels were positively correlated with the PaO2/FiO2 ratio (rs=0.40), and the TRAIL levels were negatively correlated with the multiple organ dysfunction scores (rs=-0.37).

CONCLUSIONS

Among the mediators in BAL fluid from ARDS patients, G-CSF had the most significant prognostic implications, and the sFas and TRAIL levels were correlated with clinical severity.

Role of interleukin-8 and growth-regulated oncogene-α in the chemotactic migration of all-trans retinoic acid-treated promyelocytic leukemic cells toward alveolar epithelial cells*

OBJECTIVE

Although all-trans retinoic acid (ATRA) can treat acute promyelocytic leukemia (APL), it also causes retinoic acid syndrome with presentations similar to acute respiratory distress syndrome. We investigated the role of interleukin (IL)-8 and growth-regulated oncogene (GRO)-alpha in the chemotactic transmigration of ATRA-treated NB4 (ATRA-NB4) APL cells toward A549 alveolar epithelial cells.

DESIGN

An in vitro human cell culture study.

SETTING

University hospital research laboratories.

SUBJECTS

NB4 and A549 cells.

INTERVENTIONS

NB4 and A549 cells were separately cultured with ATRA and/or dexamethasone for 1-3 days. NB4 or ATRA-NB4 cells were then placed in an upper insert and co-incubated with A549 cells or their conditioned medium located in a lower plate.

MEASUREMENTS AND MAIN RESULTS

ATRA stimulated NB4 cells to transmigrate toward the A549 cells in a time- and dose-dependent manner. Replacement of A459 condition medium by its original medium abrogated this transmigration. Only A549 cells constitutively secreted GRO-alpha, and both A549 and NB4 cells constitutively secreted IL-8, which was enhanced by ATRA. Exogenous administration of IL-8 or GRO-alpha also promoted the ATRA-NB4 transmigration. The binding assay demonstrated that ATRA-NB4 cells bound IL-8, but not GRO-alpha, more avidly. Pretreatment with antibodies directed against IL-8 and GRO-alpha receptors reduced ATRA-NB4 transmigration by about 60%. Dexamethasone did not suppress their IL-8 secretion and transmigration in ATRA-NB4 cells, but when applied to A549 cells, IL-8 secretion was suppressed but not GRO-alpha secretion, and there was attenuation of ATRA-NB4 transmigration.

CONCLUSIONS

IL-8 and GRO-alpha secreted from alveolar epithelial cells play an important role in the cell-cell interaction involved in the chemotactic transmigration of ATRA-treated APL cells toward alveolar epithelial cells.

Pneumocystis-mediated IL-8 release by macrophages requires coexpression of mannose receptors and TLR2

Interaction with the unique fungus Pneumocystis (Pc) promotes IL-8 release by human alveolar macrophages (AM), although the receptor(s) mediating IL-8 release have not been identified. TLR2 recognizes fungal components and mediates release of host defense cytokines and chemokines, although whether TLR2 mediates signaling in response to Pc is not known. In the current study, Pc induced IL-8 release by human AM, and AM pretreatment with anti-TLR2 neutralizing antibody reduced IL-8 release. However, in nonphagocytic human embryonic kidney (HEK)293 cells transfected with human TLR2 cDNA, incubation with Pc did not induce IL-8 release, whereas these same cells released IL-8 in response to the TLR2 agonist lipoteichoic acid. Targeted gene silencing of AM mannose receptors (MR; phagocytic receptors for Pc) using small interfering RNA also reduced Pc-mediated IL-8 release in human AM. However, HEK293 cells transfected with human MR cDNA alone did not release IL-8 in response to Pc. In contrast, HEK293 cells cotransfected with human TLR2 and human MR cDNA released IL-8 in response to Pc. In human AM, Pc promoted direct interaction of MR and TLR2, IL-8 release was reduced markedly upon simultaneous blocking of TLR2 and gene silencing of MR, and IL-8 release was dependent in part on transcription factor NF-kappaB and ERK1/2 and JNK MAPKs. These studies demonstrate that Pc-mediated IL-8 release by human AM requires the coexpression of MR and TLR2 and further supports the concept that combinatorial interactions of macrophage innate receptors provide specificity of host defense cell responses to infectious challenge.

Respuesta inflamatoria y apoptosis en la lesión pulmonar aguda

One of the principal mechanisms of pulmonary injury in acute respiratory distress is due to the effects of the precipitated inflammatory response. The damage produced to the alveolar epithelium and underlying endothelium depends on the sequestration and activation of inflammatory cells, which in turn exert their actions through mediators. On the other hand, apoptosis is a mechanism responsible for epithelial damage and regulation of inflammation. Response of the lung tissue subjected to mechanical ventilation stimulus is added to the previous mechanisms. All these processes flow into a series of common pathways of cellular activation. Knowledge of these mechanisms could serve to identify which patients would benefit from a specific treatment before applying therapies that act indiscriminately in the inflammatory response.

Divergent signaling pathways in phagocytic cells during sepsis

Neutrophil accumulation in the lung plays a pivotal role in the pathogenesis of acute lung injury during sepsis. Directed movement of neutrophils is mediated by a group of chemoattractants, especially CXC chemokines. Local lung production of CXC chemokines is intensified during experimental sepsis induced by cecal ligation and puncture (CLP), as reflected by rising levels of MIP-2 and cytokine-induced neutrophil chemoattractant-1 in bronchoalveolar lavage fluids. Alveolar macrophages are primed and blood neutrophils are down-regulated for production of MIP-2 and cytokine-induced neutrophil chemoattractant production in response to LPS and C5a. Under these conditions of stimulation, activation of MAPKs (p38, p42/p44) occurs in sham neutrophils but not in CLP neutrophils, while under the same conditions phosphorylation of p38 and p42/p44 occurs in both sham and CLP alveolar macrophages. These data indicate that, under septic conditions, there is impaired signaling in neutrophils and enhanced signaling in alveolar macrophages, resulting in CXC chemokine production, and C5a appears to play a pivotal role in this process. As a result, CXC chemokines increase in lung, setting the stage for neutrophil accumulation in lung during sepsis.

Cytokine regulation in SARS coronavirus infection compared to other respiratory virus infections

The pathogenesis of severe acute respiratory syndrome (SARS) is poorly understood and cytokine dysregulation has been suggested as one relevant mechanism to be explored. We compared the cytokine profile in Caco2 cells after infection of SARS coronavirus (SARS‐CoV) with other respiratory viruses including respiratory syncytial virus (RSV), influenza A virus (FluAV), and human parainfluenza virus type 2 (hPIV2). Interferon (IFN) system (production and response) was not suppressed by SARS‐CoV infection. Therefore, SARS‐CoV replication was suppressed by pretreatment with IFN. SARS‐CoV and RSV induced high levels of IL‐6 and RANTES compared with FluAV and hPIV2. Induction level of suppressor of cytokine signaling‐3 (SOCS3) by SARS‐CoV was significantly lower than that by RSV in spite of the significant production of IL‐6. Toll‐like receptors 4 and 9, which correlate with the induction of inflammatory response, were upregulated by SARS‐CoV infection. Collectively, overinduction of inflammatory cytokine and dysregulation of cytokine signaling may contribute to the immunopathology associated with “severe” inflammation in SARS. J. Med. Virol. 78:417–424, 2006. © 2006 Wiley‐Liss, Inc.

Modeling the early events of severe acute respiratory syndrome coronavirus infection in vitro

The clinical picture of severe acute respiratory syndrome (SARS) is characterized by pulmonary inflammation and respiratory failure, resembling that of acute respiratory distress syndrome. However, the events that lead to the recruitment of leukocytes are poorly understood. To study the cellular response in the acute phase of SARS coronavirus (SARS-CoV)-host cell interaction, we investigated the induction of chemokines, adhesion molecules, and DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin) by SARS-CoV. Immunohistochemistry revealed neutrophil, macrophage, and CD8 T-cell infiltration in the lung autopsy of a SARS patient who died during the acute phase of illness. Additionally, pneumocytes and macrophages in the patient's lung expressed P-selectin and DC-SIGN. In in vitro study, we showed that the A549 and THP-1 cell lines were susceptible to SARS-CoV. A549 cells produced CCL2/monocyte chemoattractant protein 1 (MCP-1) and CXCL8/interleukin-8 (IL-8) after interaction with SARS-CoV and expressed P-selectin and VCAM-1. Moreover, SARS-CoV induced THP-1 cells to express CCL2/MCP-1, CXCL8/IL-8, CCL3/MIP-1alpha, CXCL10/IP-10, CCL4/MIP-1beta, and CCL5/RANTES, which attracted neutrophils, monocytes, and activated T cells in a chemotaxis assay. We also demonstrated that DC-SIGN was inducible in THP-1 as well as A549 cells after SARS-CoV infection. Our in vitro experiments modeling infection in humans together with the study of a lung biopsy of a patient who died during the early phase of infection demonstrated that SARS-CoV, through a dynamic interaction with lung epithelial cells and monocytic cells, creates an environment conducive for immune cell migration and accumulation that eventually leads to lung injury.

Viral inhibition of IL-1- and neutrophil elastase-induced inflammatory responses in bronchial epithelial cells

Previously, we elucidated the intracellular mechanisms by which neutrophil elastase (NE) up-regulates inflammatory gene expression in bronchial epithelial cells. In this study, we examine the effects of both IL-1 and NE on inflammatory gene expression in 16HBE14o- bronchial epithelial cells and investigate approaches to abrogate these inflammatory responses. IL-1 induced IL-8 protein production in time- and dose-dependent fashions, an important observation given that IL-8 is a potent neutrophil chemoattractant and a key inflammatory mediator. IL-1 and NE were shown to activate the p38 MAPK pathway in 16HBE14o- cells. Western blot analysis demonstrated IL-1R-associated kinase 1 (IRAK-1) degradation in response to stimulation with both IL-1 and NE. In addition, the expression of dominant negative IRAK-1 (IRAK-1delta), IRAK-2delta, or IRAK-4delta inhibited IL-1- and NE-induced NF-kappaB-linked reporter gene expression. Dominant negative versions of the intracellular adaptor proteins MyD88 (MyD88delta) and MyD88 adaptor-like (Mal P/H) abrogated NE-induced NF-kappaB reporter gene expression. In contrast, only MyD88delta was found to inhibit IL-1-induced NF-kappaB reporter activity. We also investigated the vaccinia virus proteins, A46R and A52R, which have been shown to antagonize IL-1 signaling. Transfection with A46R or A52R cDNA inhibited IL-1- and NE-induced NF-kappaB and IL-8R gene expression and IL-8 protein production in primary and transformed bronchial epithelial cells. Furthermore, cytokine array studies demonstrated that IL-1 and NE can up-regulate the expression of IL-6, oncostatin M, epithelial cell-derived neutrophil activating peptide-78, growth-related oncogene family members, vascular endothelial growth factor, and GM-CSF, with induction of these proteins inhibited by the viral proteins. These findings identify vaccinia virus proteins as possible therapeutic agents for the manifestations of several inflammatory lung diseases.

Modulation of neutrophil apoptosis in plasma of patients after orthognathic surgery

BACKGROUND

Human neutrophils undergo rapid apoptosis during in vitro culture. The aim of this study was to investigate the role of interleukin-8 (IL-8) on neutrophil apoptosis in surgery-induced inflammation.

MATERIALS AND METHODS

Blood samples were drawn from 21 patients with mandibular prognathism 2 days before, and 1 and 5 days after orthognathic surgery. The IL-8 levels in the separated plasma were measured using an ELISA kit. The expression of two receptors for IL-8, CXCR1, and CXCR2, and their role in neutrophil apoptosis was evaluated using a flow cytometer.

RESULTS

The IL-8 levels in the plasma were correlated with acute inflammatory markers, such as peripheral blood neutrophil counts and C-reactive protein levels. Both IL-8 receptors were markedly raised in patient-derived neutrophils 1 day post-operatively. Recombinant IL-8 (0-100 ng/ml) suppressed apoptosis in fresh-isolated neutrophils from healthy donors dose-dependently. Neutrophil apoptosis 1 day post-operatively was slightly accelerated in the presence of fetal bovine serum compared to the value 2 days pre-operatively and 5 days post-operatively. In contrast, in the presence of autogenous plasma, neutrophil apoptosis was significantly suppressed 1 day post-operatively compared to the value 2 days pre-operatively and 5 days post-operatively. Moreover, the anti-apoptotic effect of plasma on neutrophil apoptosis was partially decreased by the addition of anti-IL-8 neutralizing antibody.

CONCLUSIONS

These results suggest that circulating neutrophils are susceptible to augmentation by IL-8 through the reinforcement of IL-8 receptors in acute inflammatory conditions. Furthermore, IL-8 may, in part, contribute to the regulation of neutrophil survival during the inflammatory response.

IL-8 increases transmission of HIV type 1 in cervical explant tissue

Interleukin-8 (IL-8) is the predominant cytokine expressed in the female genital tract of women with certain infectious/inflammatory conditions. IL-8 increased HIV-1 replication in T cells and to a greater extent in monocytes/macrophages in vitro. Physiological levels of IL-8 increased susceptibility to HIV-1 infection 5- to 8-fold in cervical explant tissues. Competitive inhibition of the IL-8 receptor CXCR2 with the small molecule inhibitor SB225002 resulted in a 45-70% decrease in cervical explant susceptibility to HIV-1 infection.

Induction of IL-8 release in lung cells via activator protein-1 by recombinant baculovirus displaying severe acute respiratory syndrome-coronavirus spike proteins: identification of two functional regions

The inflammatory response and the intracellular signaling pathway induced by severe acute respiratory syndrome (SARS)-coronavirus (CoV) were studied in lung epithelial cells and fibroblasts. SARS-CoV spike (S) protein-encoding plasmid induced activations of IL-8 promoter and AP-1, but not NF-kappaB in these cells. Mutation of the AP-1, not the kappaB site, abolished the SARS-CoV S protein-induced IL-8 promoter activity. IL-8 release was effectively induced by vAtEpGS688, a baculovirus exhibiting the aa 17-688 fragment of S protein, and this induction was attenuated by the angiotensin-converting enzyme 2 Ab. Recombinant baculovirus expressing different deletion and insertion fragments identified the functional region of S protein from aa 324-688 (particularly the N-terminal aa 324-488 and the C-terminal aa 609-688), which is responsible for IL-8 production. Activations of AP-1 DNA-protein binding and MAPKs after vAtEpGS688 transduction were demonstrated, and SARS-CoV S protein-induced IL-8 promoter activity was inhibited by the specific inhibitors of MAPK cascades. These results suggested that the S protein of SARS-CoV could induce release of IL-8 in the lung cells via activations of MAPKs and AP-1. The identification of the functional domain for IL-8 release will provide for the drug design on targeting specific sequence domains of S protein responsible for initiating the inflammatory response.

Chemokines in acute respiratory distress syndrome

A characteristic feature of all inflammatory disorders is the excessive recruitment of leukocytes to the site of inflammation. The loss of control in trafficking these cells contributes to inflammatory diseases. Leukocyte recruitment is a well-orchestrated process that includes several protein families including the large cytokine subfamily of chemotactic cytokines, the chemokines. Chemokines and their receptors are involved in the pathogenesis of several diseases. Acute lung injury that clinically manifests as acute respiratory distress syndrome (ARDS) is caused by an uncontrolled systemic inflammatory response resulting from clinical events including major surgery, trauma, multiple transfusions, severe burns, pancreatitis, and sepsis. Systemic inflammatory response syndrome involves activation of alveolar macrophages and sequestered neutrophils in the lung. The clinical hallmarks of ARDS are severe hypoxemia, diffuse bilateral pulmonary infiltrates, and normal intracardiac filling pressures. The magnitude and duration of the inflammatory process may ultimately determine the outcome in patients with ARDS. Recent evidence shows that activated leukocytes and chemokines play a key role in the pathogenesis of ARDS. The expanding number of antagonists of chemokine receptors for inflammatory disorders may hold promise for new medicines to combat ARDS.

Prospective study of neutrophil chemokine responses in trauma patients at risk for pneumonia

Neutrophil hyperactivity contributes to organ failure, whereas hypofunction permits sepsis. The chemokine receptors CXCR1 and CXCR2 are central to polymorphonuclear neutrophil (PMN) function. We prospectively assessed CXCR function and expression in PMNs from trauma patients at high risk for pneumonia and their matched volunteer controls. CXCR2-specific calcium flux and chemotaxis were desensitized by injury, returning toward normal after 1 week. CXCR1 responses were relatively maintained. These defects appeared to be caused by preferential suppression of CXCR2 surface expression. To evaluate potential mechanisms of in vivo chemokine receptor regulation further we studied cross-desensitization of chemokine receptors in normal PMNs. Susceptibility to desensitization was in the order CXCR2 > CXCR1 > formyl peptide or C5a receptors. Trauma desensitizes CXC receptors, with CXCR2 being especially vulnerable. Desensitization is most marked immediately postinjury, generally resolving by Day 7. High-affinity chemoattractant receptors responsible for PMN chemotaxis from bloodstream to tissue appear to be regulated by injury. Receptors for end-target chemoattractants regulate CXCR1 and CXCR2 but resist suppression themselves and respond normally after injury. CXCR2 desensitization occurs before pneumonia, which developed in 44% of these patients. Suppression of high-affinity PMN receptors, like CXCR2, may predispose to pneumonia after trauma or other inflammatory conditions that lead to systemic inflammatory response syndrome.

Cytokine-mediated inflammation in acute lung injury

Clinical acute lung injury (ALI) is a major cause of acute respiratory failure in critically ill patients. There is considerable experimental and clinical evidence that pro- and anti-inflammatory cytokines play a major role in the pathogenesis of inflammatory-induced lung injury from sepsis, pneumonia, aspiration, and shock. A recent multi-center clinical trial found that a lung-protective ventilatory strategy reduces mortality by 22% in patients with ALI. Interestingly, this protective ventilatory strategy was associated with a marked reduction in the number of neutrophils and the concentration of pro-inflammatory cytokines released into the airspaces of the injured lung. Further research is needed to establish the contribution of cytokines to both the pathogenesis and resolution of ALI.

Plasma inflammatory cytokines and chemokines in severe acute respiratory syndrome

Severe acute respiratory syndrome (SARS) is a recently emerged infectious disease caused by a novel coronavirus, but its immunopathological mechanisms have not yet been fully elucidated. We investigated changes in plasma T helper (Th) cell cytokines, inflammatory cytokines and chemokines in 20 patients diagnosed with SARS. Cytokine profile of SARS patients showed marked elevation of Th1 cytokine interferon (IFN)-gamma, inflammatory cytokines interleukin (IL)-1, IL-6 and IL-12 for at least 2 weeks after disease onset, but there was no significant elevation of inflammatory cytokine tumour necrosis factor (TNF)-alpha, anti-inflammatory cytokine IL-10, Th1 cytokine IL-2 and Th2 cytokine IL-4. The chemokine profile demonstrated significant elevation of neutrophil chemokine IL-8, monocyte chemoattractant protein-1 (MCP-1), and Th1 chemokine IFN-gamma-inducible protein-10 (IP-10). Corticosteroid reduced significantly IL-8, MCP-1 and IP-10 concentrations from 5 to 8 days after treatment (all P < 0.001). Together, the elevation of Th1 cytokine IFN-gamma, inflammatory cytokines IL-1, IL-6 and IL-12 and chemokines IL-8, MCP-1 and IP-10 confirmed the activation of Th1 cell-mediated immunity and hyperinnate inflammatory response in SARS through the accumulation of monocytes/macrophages and neutrophils.

Dobutamine inhibits monocyte chemoattractant protein-1 production and chemotaxis in human monocytes

It has been reported that, in patients with acute myocardial infarction or congestive heart failure, monocyte chemoattractant protein-1 (MCP-1) plays an important role in the development of inflammatory responses and that the level of MCP-1 is correlated with the severity of the disease. We conducted this study to investigate the effects of dobutamine and dopamine on lipopolysaccharide (LPS)-induced MCP-1 production in human monocytic THP-1 cells. Monocytes were incubated in vitro with LPS for 16 h at 37 degrees C in the presence or absence of dobutamine or dopamine. Enzyme-linked immunosorbent assay was used to examine the effect of dobutamine on MCP-1 synthesis, with the MCP-1 messenger RNA expression examined by reverse transcriptase-polymerase chain reaction. Dobutamine inhibited LPS-induced production of MCP-1, as well as messenger RNA expression, in a dose-dependent manner, whereas dopamine had no significant effect. Furthermore, we demonstrated that dobutamine suppressed MCP-1-induced chemotaxis and peak [Ca(2+)](i) in monocytic THP-1 cells. These findings suggest that dobutamine may modulate monocyte activation, such as chemotaxis and [Ca(2+)](i), as well as MCP-1 production, during therapy for congestive heart failure.

IMPLICATIONS

Monocyte chemoattractant protein-1 (MCP-1) plays important roles in the inflammatory processes associated with pathogenesis of cardiovascular diseases. In this study, dobutamine was found to inhibit lipopolysaccharide-induced MCP-1 production and messenger RNA expression, as well as MCP-1-induced chemotaxis and peak [Ca(2+)](i), in human monocytes.

Adrenaline inhibits lipopolysaccharide-induced macrophage inflammatory protein-1 alpha in human monocytes: the role of beta-adrenergic receptors

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) has an important role in the development of inflammatory responses during infection by regulating leukocyte trafficking and function. Our study was conducted to investigate the effect of adrenaline on lipopolysaccharide (LPS)-induced MIP-1 alpha production by human peripheral blood monocytes and human monocytic THP-1 cells. Monocytes were incubated in vitro with LPS for 4 h at 37 degrees C in the presence and absence of adrenaline and/or specific alpha- and beta-adrenergic receptor antagonists and agonists. The effects of adrenaline on MIP-1 alpha synthesis were studied at the protein level by using enzyme-linked immunosorbent assays and at the messenger RNA level by using reverse transcriptase-polymerase chain reaction. Adrenaline inhibited LPS-induced MIP-1 alpha production in a dose-dependent manner. The suppressive effect could be completely prevented by propranolol, but not by phentolamine. The specific beta-adrenergic agonist isoproterenol produced the same inhibitory effect on LPS-induced MIP-1 alpha production, whereas the alpha-adrenergic agonist phenylephrine had a minimal effect. In addition, suppression of MIP-1 alpha production was associated with an increase of intracellular cyclic adenosine monophosphate (cAMP) by the cell membrane-permeable cAMP analog dibutyryl-cAMP. Furthermore, we found that adrenaline inhibited LPS-induced MIP-1 alpha messenger RNA expression. These findings suggest that adrenaline can modulate MIP-1 alpha production in inflammatory diseases and sepsis.

Critical role for CXCR2 and CXCR2 ligands during the pathogenesis of ventilator-induced lung injury

Mortality related to adult respiratory distress syndrome (ARDS) ranges from 35% to 65%. Lung-protective ventilator strategies can reduce mortality during ARDS. The protective strategies limit tidal volumes and peak pressures while maximizing positive end-expiratory pressure. The efficacy of this approach is due to a reduction of shear-stress of the lung and release of inflammatory mediators. Ventilator-induced lung injury (VILI) is characterized by inflammation. The specific mechanism(s) that recruit leukocytes during VILI have not been elucidated. Because the murine CXC chemokines KC/CXCL1 and MIP-2/CXCL2/3, via CXCR2, are potent neutrophil chemoattractants, we investigated their role in a murine model of VILI. We compared two ventilator strategies in C57BL/6 mice: high peak pressure and high stretch (high peak pressure/stretch) versus low peak pressure/stretch for 6 hours. Lung injury and neutrophil sequestration from the high-peak pressure/stretch group were greater than those from the low-peak pressure/stretch group. In addition, lung expression of KC/CXCL1 and MIP-2/CXCL2/3 paralleled lung injury and neutrophil sequestration. Moreover, in vivo inhibition of CXCR2/CXC chemokine ligand interactions led to a marked reduction in neutrophil sequestration and lung injury. These findings were confirmed using CXCR2(-/-) mice. Together these experiments support the notion that increased expression of KC/CXCL1 and MIP-2/CXCL2/3 and their interaction with CXCR2 are important in the pathogeneses of VILI.

CXCL8((3-73))K11R/G31P antagonizes the neutrophil chemoattractants present in pasteurellosis and mastitis lesions and abrogates neutrophil influx into intradermal endotoxin challenge sites in vivo

The ELR(+) CXC chemokines are critical for protective neutrophil responses to most bacterial infections, but nevertheless can contribute importantly to the pathogenic effects of many inflammatory responses. We recently engineered a series of high affinity CXCL8/IL-8 antagonists, one of which, CXCL8((3-73))K11R/G31P, binds very strongly to neutrophils via the CXCR1 and CXCR2. Herein we show in competitive 125I-ligand binding assays that bovine CXCL8((3-73))K11R/G31P has an affinity for neutrophils that is 2-3 orders of magnitude higher than that of CXCL8/IL-8. Furthermore, when used at approximately 0.5 nM, CXCL8((3-73))K11R/G31P inhibited by 50% the chemotactic responses of neutrophils to 129 nM CXCL8/IL-8, but it also blocked chemotactic responses to the alternate ELR-CXC chemokines CXCL1/GRO alpha and CXCL5/ENA-78. Furthermore, CXCL8((3-73))K11R/G31P could inhibit by 93-97% the spectrum of neutrophil chemotactic activities present within wash fluids from clinical bacterial pneumonia or experimental endotoxin-induced mastitis lesions. Finally, intramuscular or subcutaneous application of CXCL8((3-73))K11R/G31P (75 micro g/kg) reduced by up to 97% neutrophil infiltration into intradermal endotoxin challenge sites in cattle, and prevented their circulating neutrophils from responding to CXCL8/IL-8 or ENA-78 in vitro. This data thus encourages further investigation of the potential impact of this novel antagonist on ELR-CXC chemokine-driven inflammatory disorders.

Interleukin-8 and growth-regulated oncogene alpha mediate angiogenesis in Kaposi's sarcoma

The development of the complex neoplasm Kaposi's sarcoma is dependent on infection with the Kaposi's sarcoma-associated herpesvirus (KSHV) and appears to be greatly enhanced by cytokines and human immunodeficiency virus type 1 (HIV-1) Tat. Interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) are chemokines involved in chemoattraction, neovascularization, and stimulation of HIV-1 replication. We have previously demonstrated that production of GRO-alpha is stimulated by exposure of monocyte-derived macrophages (MDM) to HIV-1. Here we show that exposure of MDM to HIV-1, viral Tat, or viral gp120 leads to a substantial increase in IL-8 production. We also demonstrate that IL-8 and GRO-alpha are induced by KSHV infection of endothelial cells and are crucial to the angiogenic phenotype developed by KSHV-infected endothelial cells in cell culture and upon implantation into SCID mice. Thus, the three known etiological factors in Kaposi's sarcoma pathogenesis-KSHV, HIV-1 Tat, and cellular growth factors-might be linked, in part, through induction of IL-8 and GRO-alpha.

The selective CXCR2 antagonist SB272844 blocks interleukin-8 and growth-related oncogene-alpha-mediated inhibition of spontaneous neutrophil apoptosis

The aims of this study were to investigate the effects of Interleukin-8 (IL-8) and Growth related oncogene-alpha (Gro-alpha) on neutrophil apoptosis and determine the potential for a selective CXCR2 antagonist to inhibit these responses. IL-8 and Gro-alpha both produced dose dependent inhibition of spontaneous human neutrophil apoptosis after 16 hours incubation (59+/-3.5% and 27.5+/-3% respectively; EC50s 2.2+/-1.8 nM, and 0.5+/-0.2 nM respectively). The pro-survival effect of a fixed concentration of agonist (IL-8 or Gro-alpha) on cultured neutrophils was abrogated by a selective CXCR2 antagonist SB272844 (K(D)s 253 nM and 49.9 nM in the presence of IL-8 or Gro-alpha respectively). Our data suggests that the anti-apoptotic effect of Gro-alpha is mediated through CXCR2 as selective CXCR2 blockade with SB272844 can potently abrogate this response. The inhibitory effect of IL-8 may in addition partly be mediated through CXCR1 as SB272844 was less potent in its ability to abrogate the anti-apoptotic effects of IL-8 when this agent was used as an agonist. CXCR2 antagonists may have a therapeutic role in controlling neutrophil-driven inflammation by reducing neutrophil recruitment and restoring neutrophils to the tissue clearance pathway of apoptosis.

CXCL8((3-73))K11R/G31P antagonizes ligand binding to the neutrophil CXCR1 and CXCR2 receptors and cellular responses to CXCL8/IL-8

We recently reported that CXCL8((3-73))K11R is a high affinity agonist of neutrophil activation and chemotactic responses. In this report we employed CXCL8((3-73))K11R as a template to generate CXCL8/IL-8 analogues with antagonist activities, using site-directed mutagenesis to introduce conservative amino acid substitutions into the first turn within the molecule's beta-pleated sheet region (G31P, P32G) and, in association with these, into the putative receptor-recognition site (T12S, H13F, F17S). We then examined their impact on the analogues' biological activities and found that a G31P substitution rendered CXCL8((3-73))K11R a high affinity antagonist of CXCL8/IL-8. The ranking (in the order of decreasing CXCL8/IL-8 antagonist activities) of the CXCL8((3-73))K11R analogues we generated was, G31P>T12S/G31P>H13F/G31P>T12S/H13F/G31P>>P32G approximately T12S/P32G approximately H13F/P32G>T12S/H13F/P32G; CXCL8((3-73))K11R/F17S did not inhibit CXCL8/IL-8-dependent responses. CXCL8((3-73))K11R/G31P had no discernible agonist (beta-glucuronidase release, chemotactic) activity, but at 12.5 ng/ml it bound to purified neutrophils more avidly than did 1.25 microg/ml CXCL8/IL-8. Furthermore, CXCL8((3-73))K11R/G31P competitively antagonized the binding of CXCR1- and CXCR2-specific antibodies to these receptors. Taken together, these data thus provide further impetus to the study of the potential efficacy of CXCL8((3-73))K11R/G31P as a broad-spectrum antagonist of the ELR-CXC chemokines in experimental and clinical settings.

Levels of the chemokines growth-related oncogene alpha and epithelial neutrophil-activating protein 78 are raised in patients with severe acute pancreatitis

BACKGROUND

Multiple organ dysfunction syndrome secondary to systemic leucocyte activation is the major cause of death following an attack of acute pancreatitis. Although plasma levels of interleukin (IL) 8 are known to be raised in acute pancreatitis, levels of other CXC chemokines such as growth-related oncogene (GRO) alpha and epithelial neutrophil-activating protein (ENA) 78, which are also potent neutrophil chemoattractants and activators, have not been measured.

METHODS

Timed plasma samples were obtained from 51 patients with acute pancreatitis, 27 with a severe attack and 24 with mild disease according to the Atlanta classification. Samples were analysed to determine levels of C-reactive protein (CRP), IL-8, GRO-alpha and ENA-78.

RESULTS

Plasma levels of IL-8, GRO-alpha and ENA-78 were increased in patients with severe as opposed to mild acute pancreatitis as early as 24 h following disease onset. Using cut-off levels of 7 pg/ml for IL-8, 70 pg/ml for GRO-alpha and 930 pg/ml for ENA-78, peak levels within the first 24 h of admission had an accuracy of 81, 71 and 87 per cent respectively in predicting the severity of an attack of acute pancreatitis.

CONCLUSION

In patients with severe acute pancreatitis plasma levels of GRO-alpha and ENA-78 were raised in addition to those of IL-8, suggesting that all three chemokines are involved in the inflammatory response in this condition.

Modulation of chemokine production in lung microvascular endothelial cells by dopamine is mediated via an oxidative mechanism

Serum concentrations of catecholamines are high in patients with sepsis or acute respiratory distress syndrome (ARDS). Because chemokines mediate the recruitment of neutrophils into inflammatory sites, we addressed the question of whether dopamine (DA) is able to influence chemokine production in endothelial cells under basal and proinflammatory conditions. To this end, lung microvascular endothelial cells (LMVEC) were stimulated or not for 24 h with the bacterial toxins lipopolysaccharide (LPS) (1 microg/ml) or lipoteichonic acid (LTA) (10 microg/ml) in the presence or absence of various concentrations of DA (1-100 microg/ml). Whereas under basal and stimulatory conditions, the addition of DA to endothelial cells dose-dependently increased IL-8 production, the production of ENA-78 and Gro-alpha was significantly inhibited (P < 0.01). This effect could still be demonstrated when the cells were stimulated for up to 3 h with LPS before DA administration. Similar findings were detected for the mRNA expression of these chemokines. The influence of DA on chemokine production was not receptor mediated and could be prevented by antioxidants or radical scavengers. Moreover, addition of H(2)O(2) to endothelial cells gave results similar to those observed with DA stimulation, suggesting a pivotal role for reactive oxygen species in DA-mediated modulation of chemokine production in endothelial cells. Our data thus demonstrate that DA administration results in the induction of oxidative stress, with profound effects on endothelial chemokine production.

Intraoperative prostaglandin E1 improves antimicrobial and inflammatory responses in alveolar immune cells

OBJECTIVE

Anesthesia and surgery decrease antimicrobial and increase proinflammatory functions of alveolar immune cells. Thus, anti-inflammatory agents that do not further suppress antimicrobial functions are required. We tested the hypothesis that intraoperative prostaglandin E1 (PGE1) suppresses proinflammatory responses and prevents the reduction in antimicrobial responses of alveolar immune cells.

DESIGN

Prospective, randomized, controlled, double-blind study.

SETTING

University hospital.

PATIENTS

A total of 40 patients undergoing elective orthopedic surgery under propofol/fentanyl anesthesia.

INTERVENTION

In double-blind fashion, the patients received PGE1 from the beginning to the end of surgery (PGE1 group, n = 20) or nothing (control group, n = 20).

METHODS AND MAIN RESULTS

Alveolar immune cells were harvested by bronchoalveolar lavage immediately after induction of anesthesia; 2, 4, and 6 hrs after induction of anesthesia; and at the end of surgery. We measured opsonized and nonopsonized phagocytosis. Microbicidal activity was evaluated to directly kill Listeria monocytogenes in alveolar macrophages. Finally, we determined the expression of proinflammatory cytokines including interleukin (IL)-1beta, IL-8, interferon-gamma, and tumor necrosis factor-alpha, and that of anti-inflammatory cytokines (IL-4 and IL-10) by semiquantitative polymerase chain reaction. Nonopsonized and opsonized phagocytosis and microbicidal activity of alveolar macrophages decreased and the expression of genes for all pro- and anti-inflammatory cytokines increased significantly over time in both groups. Starting 2-4 hrs after induction of anesthesia, the increases in gene expression of proinflammatory cytokines were 1.5-3 times smaller in the PGE1 than in the control group. Starting 6 hrs after anesthesia, the increase in gene expression of IL-10 was 1.5-3 times greater in the PGE1 than in the control group. Intraoperative decreases in phagocytic and microbial activities were the same in the two groups.

CONCLUSION

Intraoperative PGE1 not only suppressed proinflammatory responses, but also protected antimicrobial functions of alveolar macrophages, possibly because PGE1 is mostly inactivated in the pulmonary intravascular space. Our results suggest that intraoperative PGE1 protects the pulmonary immune defense in alveolar immune cells.

Peripheral blood neutrophils are hyperresponsive to IL-8 and Gro-alpha in cryptogenic fibrosing alveolitis

Cryptogenic fibrosing alveolitis (CFA) is characterized by increased pulmonary recruitment of peripheral blood neutrophils (PBNs) by interleukin (IL)-8 and other chemotactic mediators. This study investigated whether, in CFA, the PBN motility response is primed by IL-8 and growth-related oncogene (Gro)-alpha, as demonstrated in other neutrophilic inflammatory diseases, and whether the motility response of PBNs to IL-8 and Gro-alpha can be abrogated using a selective antagonist for the neutrophil receptor for IL-8 and Gro-alpha, CXCR2. The percentage of PBNs to undergo shape change (%SC), spontaneously and in response to IL-8 and Gro-alpha, was measured in patients with CFA (n=10) and controls (n=10), and the effect of the CXCR2 antagonist SB272844 studied. Plasma levels of IL-8, and Gro-alpha were measured using an enzyme-linked immunosorbent assay (ELISA). The %SC of unstimulated PBNs and the potency of Gro-alpha and IL-8 to produce neutrophil polarization was greater in CFA than in controls; dose which produces 50% of maximal effect (EC50) of IL-8 was 3.6 +/- 0.7 nM for CFA versus 6.3 +/- 1.0 nM for controls; p<0.05. SB272844 inhibited Gro-alpha induced but not IL-8 induced neutrophil shape change (equilibrium constant (KD) 123 +/- 18 nM). Plasma concentrations of Gro-alpha were increased in patients with CFA. PBNs are spontaneously activated and undergo a greater motility response to IL-8 and Gro-alpha in CFA. Interleukin-8 and growth-related oncogene-alpha, circulating in substimulatory amounts in cryptogenic fibrosing alveolitis, may prime the peripheral blood neutrophils motility response, thus increasing their capacity for migration to the lung. Selective CXCR2 antagonists may be useful to block the Gro-alpha-induced priming response whilst preserving neutrophil functions mediated by CXCR1, the alternative neutrophil receptor for interleukin-8.

Interleukin-8 stimulates human immunodeficiency virus type 1 replication and is a potential new target for antiretroviral therapy

Production of the C-X-C chemokines interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) in macrophages is stimulated by exposure to human immunodeficiency virus type 1 (HIV-1). We have demonstrated previously that GRO-alpha then stimulates HIV-1 replication in both T lymphocytes and macrophages. Here we demonstrate that IL-8 also stimulates HIV-1 replication in macrophages and T lymphocytes. We further show that increased levels of IL-8 are present in the lymphoid tissue of patients with AIDS. In addition, we demonstrate that compounds which inhibit the actions of IL-8 and GRO-alpha via their receptors, CXCR1 and CXCR2, also inhibit HIV-1 replication in both T lymphocytes and macrophages, indicating potential therapeutic uses for these compounds in HIV-1 infection and AIDS.

Intraperitoneal blood exacerbates the remote inflammatory response to murine peritonitis

BACKGROUND

This study investigated the effects of intra-abdominal blood on the systemic response to peritonitis using a murine model of hemorrhage, peritonitis, and multiple organ dysfunction syndrome.

METHODS

The model used male ICR mice subjected to hemorrhage and intraperitoneal zymosan. Half of the mice received intraperitoneal blood. Outcome measures included lung myeloperoxidase, lung edema, lung injury score, and plasma and lung tissue chemokine production.

RESULTS

Peritoneal blood (in association with peritoneal inflammation) increased lung neutrophil sequestration (myeloperoxidase) (2.56 +/- 1.42 vs. 1.45 +/- 0.49 U/left lung, p = 0.04) and lung weight (0.11 +/- 0.04 vs. 0.07 +/- 0.02 g/left lung, p = 0.02), and was associated with significantly higher chemokine levels in plasma (KC and MCP-1) and lung tissue (KC, MIP-2, and MCP-1). Both plasma and lung tissue neutrophil chemoattractants KC and MIP-2 were significantly linearly correlated with myeloperoxidase (p < 0.009), and lung tissue KC (a neutrophil chemokine) and MCP-1 and MIP-1alpha (mononuclear cell chemokines) correlated with lung injury score (p < 0.003).

CONCLUSION

Although blood alone in the peritoneal cavity was well tolerated, in conjunction with inflammation, it was synergistic in amplifying the systemic inflammatory response. The amplified lung injury in this model was associated with significant increases in circulating and lung tissue chemokine concentrations.

Human immunodeficiency virus type 1 (HIV-1)-induced GRO-alpha production stimulates HIV-1 replication in macrophages and T lymphocytes

We examined the early effects of infection by CCR5-using (R5 human immunodeficiency virus [HIV]) and CXCR4-using (X4 HIV) strains of HIV type 1 (HIV-1) on chemokine production by primary human monocyte-derived macrophages (MDM). While R5 HIV, but not X4 HIV, replicated in MDM, we found that the production of the C-X-C chemokine growth-regulated oncogene alpha (GRO-alpha) was markedly stimulated by X4 HIV and, to a much lesser extent, by R5 HIV. HIV-1 gp120 engagement of CXCR4 initiated the stimulation of GRO-alpha production, an effect blocked by antibodies to CXCR4. GRO-alpha then fed back and stimulated HIV-1 replication in both MDM and lymphocytes, and antibodies that neutralize GRO-alpha or CXCR2 (the receptor for GRO-alpha) markedly reduced viral replication in MDM and peripheral blood mononuclear cells. Therefore, activation of MDM by HIV-1 gp120 engagement of CXCR4 initiates an autocrine-paracrine loop that may be important in disease progression after the emergence of X4 HIV.

Association of IL-8 and MCP-1 with the development of reexpansion pulmonary edema in rabbits

BACKGROUND

The aim of this study is to determine the relationships between the cytokines and the inflammatory response in reexpansion pulmonary edema (RPE).

METHODS

We examined the cell population, epithelial permeability measured by Evans blue dye (EB), betaglucuronidase and cytokine concentrations in bronchoalveolar lavage fluid (BALF) and/or blood using a rabbit RPE model.

RESULTS

We confirmed that RPE is characterized by recruitment of polymorphonuclear leukocytes (PMNs), the release of PMN granular contents into the air spaces, and increased vascular permeability. These findings were highly correlated with increased interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) concentrations in the BALF. Growth related oncogene (GRO) was detected in the BALF from only 2 of the 7 reexpanded lungs while TNFalpha was not detected in any rabbits. A similar but less severe inflammatory response to the reexpanded lung was found in the contralateral lung.

CONCLUSIONS

IL-8 and MCP-1 may play important roles in the development of RPE; the inflammatory response is independent of TNFalpha and unilateral reexpansion of the lung induces an inflammatory response not only in the reexpanded lung but also in the contralateral lung.

Local inflammatory responses following bronchial endotoxin instillation in humans

To study local lung inflammation, 34 subjects had endotoxin (1-4 ng/kg) instilled into a lung segment and saline instilled into a contralateral segment followed by bronchoalveolar lavage (BAL) at 2 h, 6 h, 24 h, or 48 h. Endotoxin instillation resulted in a focal inflammatory response with a distinct time course. An early phase (2 h to 6 h) revealed an increase in neutrophils (p = 0.0001) with elevated cytokines (tumor necrosis factor [TNF]-alpha, TNF receptors [TNFR], interleukin [IL]-1beta, IL-1 receptor antagonist, IL-6, granulocyte-colony-stimulating factor [G-CSF], all p < or = 0.002, but no change in IL-10) and chemokines (IL-8, epithelial neutrophil activating protein-78, monocyte chemotactic protein-1, macrophage inflammatory protein [MIP]-1alpha, MIP-1beta, all p < or = 0.001, but no change in growth-regulated peptide-alpha). A later phase (24 h to 48 h) showed increased neutrophils, macrophages, monocytes, and lymphocytes (all p < or = 0.02), and a return to basal levels of most mediators. Elevated levels of inflammatory markers (TNFR(1), TNFR(2), L-selectin, lactoferrin, and myeloperoxidase) persisted in the BAL at 48 h (p < or = 0.001). Increased permeability to albumin occurred throughout both phases (p = 0.001). Blood C-reactive protein, serum amyloid A, IL-6, IL-1ra, G-CSF, but not TNF-alpha increased by 8 h (all p < or = 0.008). The local pulmonary inflammatory response to endotoxin has a unique qualitative and temporal profile of inflammation compared with previous reports of intravenous endotoxin challenges. This model provides a means to investigate factors that initiate, amplify, and resolve local lung inflammation.