Oncostatin M is a potent stimulator of alpha1-antitrypsin secretion in lung epithelial cells: modulation by transforming growth factor-beta and interferon-gamma

Aqueous humor perturbations in chronic smokers: a proteomic study

The detrimental effects of smoking are multisystemic and its effects on the eye health are significant. Smoking is a strong risk factor for age-related nuclear cataract, age-related macular degeneration, glaucoma, delayed corneal epithelial healing and increased risk of cystoid macular edema in patients with intermediate uveitis among others. We aimed to characterize the aqueous humor (AH) proteome in chronic smokers to gain insight into its perturbations and to identify potential biomarkers for smoking-associated ocular pathologies. Compared to the control group, chronic smokers displayed 67 (37 upregulated, 30 downregulated) differentially expressed proteins (DEPs). Analysis of DEPs from the biological point of view revealed that they were proteins involved in complement activation, lymphocyte mediated immunity, innate immune response, cellular oxidant detoxification, bicarbonate transport and platelet degranulation. From the molecular function point of view, DEPs were involved in oxygen binding, oxygen carrier activity, hemoglobin binding, peptidase/endopeptidase/cysteine-type endopeptidase inhibitory activity. Several of the upregulated proteins were acute phase reactant proteins such as clusterin, alpha-2-HS-glycoprotein, fibrinogen, alpha-1-antitrypsin, C4b-binding protein and serum amyloid A-2. Further research should confirm if these proteins might serve as biomarkers or therapeutic target for smoking-associated ocular diseases.

PCR Analysis to Identify AAT Gene Promoters and Splice Variants

This chapter explores the methods used for the analysis of alpha1-antitrypsin gene expression. This includes the use of the polymerase chain reaction (PCR), reverse transcriptase-PCR (RT-PCR), and whole transcriptome analysis combined with parallel DNA sequencing to understand the processes involved in AAT expression.

Alpha-1 antitrypsin protects against phosgene-induced acute lung injury by activating the ID1-dependent anti-inflammatory response

Phosgene is widely used as an industrial chemical, and phosgene inhalation causes acute lung injury (ALI), which may further progress into pulmonary edema. Currently, an antidote for phosgene poisoning is not known. Alpha-1 antitrypsin (α1-AT) is a protease inhibitor used to treat patients with emphysema who are deficient in α1-AT. Recent studies have revealed that α1-AT has both anti-inflammatory and anti-SARS-CoV-2 effects. Herein, we aimed to investigate the role of α1-AT in phosgene-induced ALI. We observed a time-dependent increase in α1-AT expression and secretion in the lungs of rats exposed to phosgene. Notably, α1-AT was derived from neutrophils but not from macrophages or alveolar type II cells. Moreover, α1-AT knockdown aggravated phosgene- and lipopolysaccharide (LPS)-induced inflammation and cell death in human bronchial epithelial cells (BEAS-2B). Conversely, α1-AT administration suppressed the inflammatory response and prevented death in LPS- and phosgene-exposed BEAS-2B cells. Furthermore, α1-AT treatment increased the inhibitor of DNA binding 1 (ID1) gene expression, which suppressed NF-κB pathway activation, reduced inflammation, and inhibited cell death. These data demonstrate that neutrophil-derived α1-AT acts as a self-protective mechanism, which protects against phosgene-induced ALI by activating the ID1-dependent anti-inflammatory response. This study may provide novel strategies for the treatment of patients with phosgene-induced ALI.

The Induction of Alpha-1 Antitrypsin by Vitamin D in Human T Cells Is TGF-β Dependent: A Proposed Anti-inflammatory Role in Airway Disease

Background: Vitamin D upregulates anti-inflammatory and antimicrobial pathways that promote respiratory health. Vitamin D synthesis is initiated following skin exposure to sunlight, however nutritional supplementation can be required to address deficiency, for example during the winter months or due to cultural constraints. We recently reported that 1α,25-dihydroxyvitamin D3 (1,25(OH)₂D3) treatment induced alpha-1 antitrypsin (AAT) expression in CD4+, but not CD8+ T cells, with evidence supporting an immunoregulatory role.

Research Question: To understand the relationship between vitamin D, lung AAT levels and T lymphocytes further we investigated whether TGF-β is required as a co-factor for 1,25(OH)₂D3-induced upregulation of AAT by vitamin D in CD8+ T cells in vitro and correlated circulating vitamin D levels with lung AAT levels in vivo.

Results: 1,25(OH)₂D3 in combination with TGF-β1 increased AAT expression by CD8+ T cells, as well as VDR and RXRα gene expression, which may partly explain the requirement for TGF-β. CD4+ T cells may also require autocrine stimulation with TGF-β as a co-factor since 1,25(OH)₂D3 was associated with increased TGF-β bioactivity and neutralisation of TGF-β partially abrogated 1,25(OH)₂D3-induced SERPINA1 gene expression. Neither CD4+ nor CD8+ T cells responded to the circulating vitamin D precursor, 25-hydroxyvitamin D3 for induction of SERPINA1, suggesting that local generation of 1,25(OH)₂D3 is required. Transcriptional gene profiling studies previously demonstrated that human bronchial epithelial cells rapidly increased TGF-β2 gene expression in response to 1,25(OH)₂D3. Here, human epithelial cells responded to precursor 25(OH)D3 to increase bioactive TGF-β synthesis. CD8+ T cells responded comparably to TGF-β1 and TGF-β2 to increase 1,25(OH)₂D3-induced AAT. However, CD8+ T cells from adults with AAT-deficiency, homozygous for the Z allele of SERPINA1, were unable to mount this response. AAT levels in the airways of children with asthma and controls correlated with circulating 25(OH)D3.

Conclusions: Vitamin D increases AAT expression in human T cells and this response is impaired in T cells from individuals homozygous for the Z allele of SERPINA1 in a clinic population. Furthermore, a correlation between circulating vitamin D and airway AAT is reported. We propose that vitamin D-induced AAT contributes to local immunomodulation and airway health effects previously attributed to vitamin D.

Methylation of SERPINA1 gene promoter may predict chronic obstructive pulmonary disease in patients affected by acute coronary syndrome

Background

Diagnostic biomarkers for detecting chronic obstructive pulmonary disease (COPD) in acute coronary syndrome (ACS) patients are not available. SERPINA1, coding for the most potent circulating anti-inflammatory protein in the lung, has been found to be differentially methylated in blood cells from COPD patients. This study aimed to investigate the methylation profile of SERPINA1 in blood cells from ACS patients, with (COPD+) or without COPD (COPD−).

Methods

Blood samples were from 115 ACS patients, including 30 COPD+ and 85 COPD− according to lung function phenotype, obtained with spirometry. DNA treated with sodium bisulfite was PCR-amplified at SERPINA1 promoter region. Methylation analysis was carried out by sequencing the PCR products. Lymphocytes count in ACS patients was recorded at hospital admission and discharge.

Results

SERPINA1 was hypermethylated in 24/30 (80%) COPD+ and 48/85 (56.5%) COPD− (p < 0.05). Interestingly, at hospital discharge, lymphocytes count was higher in COPD− patients carrying SERPINA1 hypermethylated (1.98 × 10³ ± 0.6 cell/µl) than in COPD− carrying SERPINA1 hypomethylated (1.7 × 10³ ± 0.48 cell/µl) (p < 0.05).

Conclusions

SERPINA1 is hypermethylated in blood cells from COPD+ patients. COPD− carrying SERPINA1 hypermethylated and high lymphocytes count may be at risk of COPD development. Therefore, SERPINA1 hypermethylation may represent a potential biomarker for predicting COPD development in ACS patients.

Oncostatin M and TNF-α Induce Alpha-1 Antitrypsin Production in Undifferentiated Adipose Stromal Cells

Alpha-1 antitrypsin (A1AT), a circulating acute-phase reactant antiprotease, is produced and secreted by cells of endodermal epithelial origin, primarily hepatocytes, and by immune cells. Deficiency of A1AT is associated with increased risk of excessive lung inflammation and injury, especially following chronic cigarette smoke (CS) exposure. Exogenous administration of mesenchymal progenitor cells, including adipose tissue-derived stromal/stem cells (ASC), alleviates CS-induced lung injury through paracrine effectors such as growth factors. It is unknown, however, if mesodermal ASC can secrete functional A1AT and if CS exposure affects their A1AT production. Human ASC collected via liposuction from nonsmoking or smoking donors were stimulated by inflammatory cytokines tumor necrosis alpha (TNFα), oncostatin M (OSM), and/or dexamethasone (DEX) or were exposed to sublethal concentrations of ambient air control or CS extract (0.5%-2%). We detected minimal expression and secretion of A1AT by cultured ASC during unstimulated conditions, which significantly increased following stimulation with TNFα or OSM. Furthermore, TNFα and OSM synergistically enhanced A1AT expression and secretion, which were further increased by DEX. The A1AT transcript variant produced by stimulated ASC resembled that produced by bronchial epithelial cells rather than the variant produced by monocytes/macrophages. While the cigarette smoking status of the ASC donor had no measurable effect on the ability of ASC to induce A1AT expression, active exposure to CS extract markedly reduced A1AT expression and secretion by cultured ASC, as well as human tracheobronchial epithelial cells. ASC-secreted A1AT covalently complexed with neutrophil elastase in control ASC, but not in cells transfected with A1AT siRNA. Undifferentiated ASC may require priming to secrete functional A1AT, a potent antiprotease that may be relevant to stem cell therapeutic effects.

Activation of the c-Jun N-terminal kinase pathway aggravates proteotoxicity of hepatic mutant Z alpha1-antitrypsin

Alpha1-antitrypsin deficiency is a genetic disease that can affect both the lung and the liver. The vast majority of patients harbor a mutation in the serine protease inhibitor 1A (SERPINA1) gene leading to a single amino acid substitution that results in an unfolded protein that is prone to polymerization. Alpha1-antitrypsin defciency-related liver disease is therefore caused by a gain-of-function mechanism due to accumulation of the mutant Z alpha1-antitrypsin (ATZ) and is a key example of an disease mechanism induced by protein toxicity. Intracellular retention of ATZ triggers a complex injury cascade including apoptosis and other mechanisms, although several aspects of the disease pathogenesis are still unclear. We show that ATZ induces activation of c-Jun N-terminal kinase (JNK) and c-Jun and that genetic ablation of JNK1 or JNK2 decreased ATZ levels in vivo by reducing c-Jun-mediated SERPINA1 gene expression. JNK activation was confirmed in livers of patients homozygous for the Z allele, with severe liver disease requiring hepatic transplantation. Treatment of patient-derived induced pluripotent stem cell-hepatic cells with a JNK inhibitor reduced accumulation of ATZ.

CONCLUSION

These data reveal that JNK is a key pathway in the disease pathogenesis and add new therapeutic entry points for liver disease caused by ATZ. (Hepatology 2017;65:1865-1874).

Alpha-1 Antitrypsin Levels and Polymorphisms in Interstitial Lung Diseases

BACKGROUND/AIM

Alpha-1 antitrypsin deficiency may be a potential predisposing factor for interstitial lung fibrosis. We investigated alpha-1 antitrypsin levels and its polymorphisms in patients with interstitial lung disease.

MATERIALS AND METHODS

A total of 103 interstitial lung disease patients were compared.

RESULTS

The mean alpha-1 antitrypsin level in idiopathic interstitial pneumonia patients was 1.67 ± 0.33 g/L, and it was 1.54 ± 0.37 g/L in patients with nonidiopathic interstitial pneumonia (P = 0.13). Low alpha-1 antitrypsin levels were more frequently observed in nonidiopathic interstitial pneumonia patients compared with idiopathic interstitial pneumonia, but the difference was not statistically significant (8.9% vs. 0%, respectively, P = 0.4). In 100 patients, the normal PiMM genotype was detected, while abnormal ones (PiMZ, n = 2, 1.9%; PiMS, n = 1, 0.97%) were determined in three cases. When the frequency of alpha-1 antitrypsin polymorphism in interstitial lung disease patients was compared with the data of the healthy population, no significant difference was detected for the PiMZ and PiMS variants (P = 0.15 and P = 0.44, respectively).

CONCLUSION

Lower levels of serum alpha-1 antitrypsin were more frequent in nonidiopathic interstitial pneumonia patients than idiopathic interstitial pneumonia without an increase in genetic polymorphism. The difference was not statistically significant.

Alternative transcripts of the SERPINA1 gene in alpha-1 antitrypsin deficiency

Background

SERPINA1 is the gene for alpha-1 antitrypsin (AAT), an acute phase protein with anti-protease and immunoregulatory activities. Mutations in SERPINA1 gene cause AAT deficiency and predispose individuals to early-onset emphysema and liver diseases. Expression of the SERPINA1 gene is regulated by different promoters and alternative splicing events among non-coding exons 1A, 1B and 1C.

Methods

We have developed three quantitative PCR (QT-PCR) assays (1A, 1B and 1C). These assays were applied for the analysis of SERPINA1 alternative transcripts in: (1) 16 human tissues and (2) peripheral blood leukocytes from 33 subjects with AAT mutations and 7 controls.

Results

Tissue-specific expression was found for the SERPINA1 transcripts. The 1A transcripts were mainly expressed in leukocytes and lung tissue while those detected with the 1B assay were highly restricted to leukocytes. Only 1B transcripts significantly correlated with serum AAT levels. The 1C transcripts were specifically found in lung, liver, kidney and pancreas. Furthermore, the expression of transcripts was related to AAT genotypes. While deficient variants of AAT had no pronounced effect on the transcript expression, null alleles were associated with significant reduction of different transcripts.

Conclusions

The possibility to discriminate between SERPINA1 alternative splicing products will help us to understand better the regulation of SERPINA1 gene and its association with SERPINA1 mutations-related diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0585-y) contains supplementary material, which is available to authorized users.

Oncostatin M mediates STAT3-dependent intestinal epithelial restitution via increased cell proliferation, decreased apoptosis and upregulation of SERPIN family members

Objective

Oncostatin M (OSM) is produced by activated T cells, monocytes, and dendritic cells and signals through two distinct receptor complexes consisting of gp130 and LIFR (I) or OSMR-β and gp130 (II), respectively. Aim of this study was to analyze the role of OSM in intestinal epithelial cells (IEC) and intestinal inflammation.

Methods

OSM expression and OSM receptor distribution was analyzed by PCR and immunohistochemistry experiments, signal transduction by immunoblotting. Gene expression studies were performed by microarray analysis and RT-PCR. Apoptosis was measured by caspases-3/7 activity. IEC migration and proliferation was studied in wounding and water soluble tetrazolium assays.

Results

The IEC lines Caco-2, DLD-1, SW480, HCT116 and HT-29 express mRNA for the OSM receptor subunits gp130 and OSMR-β, while only HCT116, HT-29 and DLD-1 cells express LIFR mRNA. OSM binding to its receptor complex activates STAT1, STAT3, ERK-1/2, SAPK/JNK-1/2, and Akt. Microarray analysis revealed 79 genes that were significantly up-regulated (adj.-p≤0.05) by OSM in IEC. Most up-regulated genes belong to the functional categories “immunity and defense” (p = 2.1×10⁻⁷), “apoptosis” (p = 3.7×10⁻⁴) and “JAK/STAT cascade” (p = 3.4×10⁻⁶). Members of the SERPIN gene family were among the most strongly up-regulated genes. OSM significantly increased STAT3- and MEK1-dependent IEC cell proliferation (p<0.05) and wound healing (p = 3.9×10⁻⁵). OSM protein expression was increased in colonic biopsies of patients with active inflammatory bowel disease (IBD).

Conclusions

OSM promotes STAT3-dependent intestinal epithelial cell proliferation and wound healing in vitro. Considering the increased OSM expression in colonic biopsy specimens of patients with active IBD, OSM upregulation may modulate a barrier-protective host response in intestinal inflammation. Further in vivo studies are warranted to elucidate the exact role of OSM in intestinal inflammation and the potential of OSM as a drug target in IBD.

Alpha-1 antitrypsin: a potent anti-inflammatory and potential novel therapeutic agent

Alpha-1 antitrypsin (AAT) has long been thought of as an important anti-protease in the lung where it is known to decrease the destructive effects of major proteases such as neutrophil elastase. In recent years, the perception of this protein in this simple one dimensional capacity as an anti-protease has evolved and it is now recognised that AAT has significant anti-inflammatory properties affecting a wide range of inflammatory cells, leading to its potential therapeutic use in a number of important diseases. This present review aims to discuss the described anti-inflammatory actions of AAT in modulating key immune cell functions, delineate known signalling pathways and specifically to identify the models of disease in which AAT has been shown to be effective as a therapy.

Differences in acute lung response to elastase instillation in two rodent species may determine differences in severity of emphysema development

Elastase intratracheal instillation induces early emphysema in rodents. However, Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats. We have reported species differences in oxidant/antioxidant balance modulating antiprotease function early after instillation. We now hypothesize that other components of the initial lung response to elastase might also be species-dependent. Sprague-Dawley rats and Syrian Golden hamsters received a single dose of pancreatic elastase (0.55 U/100 g body wt) to study acute lung injury biomarkers. Using serum, lung, and bronchoalveolar lavage fluid (BALF) samples, we evaluated changes in alveolar-capillary permeability, alpha 1-antitrypsin (α(1)-AT) concentration and activity, glutathione content, and proinflammatory cytokines. Rats showed a large increase in alveolar-capillary permeability and few hemorrhagic changes, whereas hamsters exhibited large hemorrhagic changes (P < 0.01) and mild transendothelial passage of proteins. Western blots showed a 30-fold increase in BALF α(1)-AT concentration in rats and only a 7-fold increase in hamsters (P < 0.001), with [α(1)-AT-elastase] complexes only in rats, suggesting differences in antiprotease function. This was confirmed by the α(1)-AT bioassay showing 20-fold increase in α(1)-AT activity in rats and only twofold increase in hamsters (P < 0.001). In rats, results were preceded by a 3-, 60-, and 20-fold increase in IL-6, IL-1β, and TNF-α respectively (P < 0.001). In hamsters, only IL-1β and TNF-α showed mild increases. All parameters studied were back to baseline by 4 days. In conclusion, several components of the initial lung response showed species differences. Cytokine release pattern and functional inhibition of α(1)-AT were the most significant components differing among species and could account for differences in susceptibility to elastase.

Transforming growth factor-beta1 shows an incremental osteoinductive dose-response relationship

OBJECTIVE

To determine if there is a dose-response curve for TGF-beta1 in a rabbit calvarial defect model.

STUDY DESIGN

Controlled animal study using arms of increasing concentrations of TGF-beta1 to evaluate the osteoinductive potential of each arm.

METHODS

Sixteen skeletally mature New Zealand white rabbits were randomized into control and experimental arms. Incremental doses of TGF-beta1 delivered in an inactivated guanidine-extracted demineralized bone matrix (Gu-DBM) carrier were implanted into a critically sized calvarial defect. The animals were sacrificed at 4 weeks and histomorphometric analysis was then accomplished.

RESULTS

TGF-beta1 showed a dose-response relationship, with the higher doses chosen for this study causing more robust osteoinduction.

CONCLUSIONS

In this pilot dosing study, TGF-beta1 demonstrates increasing osteoinduction with increasing dose levels in this animal model.

The alpha-1-antitrypsin gene promoter in human A549 lung derived cells, and a novel transcription initiation site

Alpha-1-antitrypsin (AAT), also called serine proteinase inhibitor A1 (Serpin A1), is the most abundant serpin in human plasma. A major physiological role of AAT is to protect the lung from the destructive effects of excess uninhibited neutrophil elastase. During inflammation, circulating levels of AAT may increase twofold-to-threefold as part of the acute-phase response. The liver is the main contributor to this increase. However, local synthesis may provide an important mechanism for controlling neutrophil elastase activity at sites of inflammation, and previous studies have shown a marked increase in production after cytokine stimulation. In the current study we report a distinct transcription initiation site for AAT expression in the lung alveolar epithelial cell line A549, which is located nine bases upstream of the previously mapped full-length monocyte transcription start-site, and show using site-directed mutagenesis that two Sp1 sites and a putative TATA box are functional. EMSA experiments provide evidence for Sp1 and Sp3 binding to these two Sp1 sites. We have also mapped the minimal promoter region and a cell-specific element essential for expression in A549 cells, both of which reside in an 865bp fragment upstream of the transcription start-site. Understanding the mechanisms of AAT gene regulation in a lung-derived cell line has important implications for understanding the control of localised lung tissue damage which occurs as a result of excess proteolytic activity.

Regulated expression of the IL-31 receptor in bronchial and alveolar epithelial cells, pulmonary fibroblasts, and pulmonary macrophages

Interleukin-31 (IL-31), an IL-6 cytokine family member, is proposed to play a role in animal models of airway hyperreactivity. It is produced by activated T cells and signals via a heterodimeric receptor complex composed of IL-31Ralpha and OSMRbeta. Only low levels of IL-31Ralpha expression have been demonstrated in pulmonary epithelial cell lines, however, and little is known about the ability to regulate its expression and signaling. Therefore, primary cultures of human bronchial and alveolar epithelial cells, pulmonary fibroblasts, pulmonary macrophages, and established lines of immortalized bronchial epithelial cells (HBE) and alveolar carcinoma cells (A549) were analyzed by RT-PCR, immunoblotting, and thymidine incorporation. Distinct, cell type-specific regulation of IL-31Ralpha expression was detected. Transforming growth factor-beta (TGF-beta) enhanced IL-31Ralpha mRNA expression in primary cultures and established lines of epithelial cells, but not in macrophages. In contrast, interferon-gamma (IFN-gamma) induced IL-31Ralpha mRNA expression in macrophages. IL-31Ralpha protein expression was below detection threshold in primary epithelial cell cultures but was detectable in A549 cells and increased with TGF-beta treatment. In HBE and A549 cells, TGF-beta pretreatment increased IL-31-mediated Stat3 and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. In A549 cells, TGF-beta magnified IL-31-dependent suppression of proliferation. The data suggest that increased IL-31Ralpha expression correlates with an enhanced response to IL-31.

Neutrophil elastase (NE) and NE inhibitors: canonical and noncanonical functions in lung chronic inflammatory diseases (cystic fibrosis and chronic obstructive pulmonary disease)

Proteases and antiproteases have multiple important roles both in normal homeostasis and during inflammation. Antiprotease molecules may have developed in a parallel network, consisting of "alarm" and "systemic" inhibitors. Their primary function was thought until recently to mainly prevent the potential injurious effects of excess release of proteolytic enzymes, such as neutrophil elastase (NE), from inflammatory cells. However, recently, new potential roles have been ascribed to these antiproteases. We will review "canonical" and new "noncanonical" functions for these molecules, and more particularly, those pertaining to their role in innate and adaptive immunity (antibacterial activity and biasing of the adaptive immune response).

Hereditary alpha-1-antitrypsin deficiency and its clinical consequences

Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder that manifests as pulmonary emphysema, liver cirrhosis and, rarely, as the skin disease panniculitis, and is characterized by low serum levels of AAT, the main protease inhibitor (PI) in human serum. The prevalence in Western Europe and in the USA is estimated at approximately 1 in 2,500 and 1 : 5,000 newborns, and is highly dependent on the Scandinavian descent within the population. The most common deficiency alleles in North Europe are PI Z and PI S, and the majority of individuals with severe AATD are PI type ZZ. The clinical manifestations may widely vary between patients, ranging from asymptomatic in some to fatal liver or lung disease in others. Type ZZ and SZ AATD are risk factors for the development of respiratory symptoms (dyspnoea, coughing), early onset emphysema, and airflow obstruction early in adult life. Environmental factors such as cigarette smoking, and dust exposure are additional risk factors and have been linked to an accelerated progression of this condition. Type ZZ AATD may also lead to the development of acute or chronic liver disease in childhood or adulthood: prolonged jaundice after birth with conjugated hyperbilirubinemia and abnormal liver enzymes are characteristic clinical signs. Cirrhotic liver failure may occur around age 50. In very rare cases, necrotizing panniculitis and secondary vasculitis may occur. AATD is caused by mutations in the SERPINA1 gene encoding AAT, and is inherited as an autosomal recessive trait. The diagnosis can be established by detection of low serum levels of AAT and isoelectric focusing. Differential diagnoses should exclude bleeding disorders or jaundice, viral infection, hemochromatosis, Wilson's disease and autoimmune hepatitis. For treatment of lung disease, intravenous alpha-1-antitrypsin augmentation therapy, annual flu vaccination and a pneumococcal vaccine every 5 years are recommended. Relief of breathlessness may be obtained with long-acting bronchodilators and inhaled corticosteroids. The end-stage liver and lung disease can be treated by organ transplantation. In AATD patients with cirrhosis, prognosis is generally grave.

Methods for studying stem cells: adult stem cells for lung repair

Recent progress in lung biology includes the description of a series of pulmonary stem and progenitor cells involved in homeostasis and regeneration of the respiratory system. Moreover, the contribution of extrapulmonary stem cells to healthy and pathological lung tissue has been observed and the developmental biology of such processes should provide important hints for understanding maintenance and repair of adult lung structure and function. Despite such remarkable advances, the phenotypic and especially the functional characterization of these stem and progenitor cells, and their derivatives, along with an understanding of the molecular cues and pathways underlying differentiation into specific respiratory lineages is still in its infancy. Accordingly, the role of endogenous and extrapulmonary stem cells in normal tissue repair and pathogenesis is still largely mysterious and added basic knowledge is required in order to explore their potential for novel regenerative therapies. This review provides an overview of the current state of the art in adult lung stem cell biology including technical aspects of isolation, characterization and differentiation, and a discussion of perspectives for future regenerative therapies.

Alpha-1-Antitrypsin Deficiency: Current Concepts

Since the condition was first described four decades ago, alpha-1-antitrypsin (A1AT) deficiency has served as a model for other disease processes. A1AT is the archetypal serpin designed to ensnare proteases, a process that involves significant conformational change within the molecule. Mutations in the A1AT gene lead to misfolding of the protein and accumulation within the endoplasmic reticulum of hepatocytes resulting in two different pathologic processes. First, the accumulation of mutant A1AT protein has a directly toxic effect on the liver, resulting in hepatitis and cirrhosis. Second, the resultant decrease in circulating A1AT results in protease-antiprotease imbalance at the lung surface and emphysema ensues. A1AT deficiency therefore can be seen as two distinct disease processes: a conformational disease of the liver and a protease-antiprotease imbalance of the lung. This two-stage model of disease in A1AT deficiency is elegant in its simplicity and goes a long way to explaining the clinical manifestations that occur in patients with the condition. However, some aspects of the disease are not readily explained. Recent findings suggest that there is more to the lung damage in A1AT deficiency than simple proteolytic insult and that the presence of the mutant protein itself is proinflammatory and may indeed cause chronic injury to the cells that produce it. This review discusses some of the emerging concepts in alpha-1-antitrypsin research and outlines the implications these new ideas may have for treatment of this condition.

A pure population of lung alveolar epithelial type II cells derived from human embryonic stem cells

Alveolar epithelial type II (ATII) cells are small, cuboidal cells that constitute approximately 60% of the pulmonary alveolar epithelium. These cells are crucial for repair of the injured alveolus by differentiating into alveolar epithelial type I cells. ATII cells derived from human ES (hES) cells are a promising source of cells that could be used therapeutically to treat distal lung diseases. We have developed a reliable transfection and culture procedure, which facilitates, via genetic selection, the differentiation of hES cells into an essentially pure (>99%) population of ATII cells (hES-ATII). Purity, as well as biological features and morphological characteristics of normal ATII cells, was demonstrated for the hES-ATII cells, including lamellar body formation, expression of surfactant proteins A, B, and C, alpha-1-antitrypsin, and the cystic fibrosis transmembrane conductance receptor, as well as the synthesis and secretion of complement proteins C3 and C5. Collectively, these data document the successful generation of a pure population of ATII cells derived from hES cells, providing a practical source of ATII cells to explore in disease models their potential in the regeneration and repair of the injured alveolus and in the therapeutic treatment of genetic diseases affecting the lung.

Serpin A1 and CD91 as host instruments against HIV-1 infection: are extracellular antiviral peptides acting as intracellular messengers?

Serpin A1 (alpha1-antitrypsin, alpha1-proteinase inhibitor) has been shown to be a non-cytolytic antiviral factor present in blood and effective against HIV infection. The best known physiological role of serpin A1 is to inhibit neutrophil elastase, a proteinase which is secreted by neutrophils at sites of infection and inflammation. Decreased HIV-infectivity is associated with decreased density of membrane-associated elastase. The enzyme may facilitate binding of the HIV membrane protein gp120 to host cells, and it specifically cleaves SDF-1, the physiological ligand of the HIV-1 co-receptor CXCR4. It has been suggested that one of the actions of serpin A1 as antiviral agent is to reduce HIV infectivity, and this property could be due to elastase inhibition. However, the most dramatic effect of serpin A1 is inhibition of HIV production. In vitro experiments indicate that the C-terminal peptide of serpin A1, produced during the formation of the complex of serpin with serine proteinases, may be responsible for the inhibition of HIV-1 expression in infected cells. This peptide, an integral part of the serpin-enzyme complex, is internalized by several scavenger receptors. Peptides corresponding to the C-terminal section of serpin A1 inhibit HIV-1 long-terminal-repeat-driven transcription and interact with nuclear proteins, such as alpha1-fetoprotein transcription factor. LDL-receptor-related protein 1 (LRP1/CD91), the best known receptor for serpin-enzyme complexes, is up-regulated in monocytes of HIV-1-infected true non-progressors. CD91 could be one of the major players in host resistance against HIV-1. It has the capacity of internalizing antiviral peptides such as serpin C-terminal fragments and alpha-defensins, and is at the same time the receptor for heat-shock proteins in antigen-presenting cells, in which chaperoned viral peptides could lead to the induction of cytotoxic T-cell responses.

Interleukin-31 and oncostatin-M mediate distinct signaling reactions and response patterns in lung epithelial cells

Lung epithelial cells are primary targets of oncostatin M (OSM) and, to a lower degree, of interleukin (IL)-6 and IL-31, all members of the IL-6 cytokine family. The OSM receptor (OSMR) signals through activation of STAT and mitogen-activated protein kinase pathways to induce genes encoding differentiated cell functions, reduce cell-cell interaction, and suppress cell proliferation. IL-31 functions through the heteromeric IL-31 receptor, which shares with OSMR the OSMRbeta subunit, but does not engage gp130, the common subunit of all other IL-6 cytokine receptors. Because the response of epithelial cells to IL-31 is unknown, the action of IL-31 was characterized in the human alveolar epithelial cell line A549 in which the expression of the ligand-binding IL-31Ralpha subunit was increased. IL-31 initiated signaling that differed from other IL-6 cytokines by the particularly strong recruitment of the STAT3, ERK, JNK, and Akt pathways. IL-31 was highly effective in suppressing proliferation by altering expression of cell cycle proteins, including up-regulation of p27(Kip1) and down-regulation of cyclin B1, CDC2, CDK6, MCM4, and retinoblastoma. A single STAT3 recruitment site (Tyr-721) in the cytoplasmic domain of IL-31Ralpha exerts a dominant function in the entire receptor complex and is critical for gene induction, morphological changes, and growth inhibition. The data suggest that inflammatory and immune reactions involving activated T-cells regulate functions of epithelial cells by IL-6 cytokines through receptor-defined signaling reactions.

Alpha1-antitrypsin deficiency: current perspective on research, diagnosis, and management

The Alpha One International Registry (AIR), a multinational research program focused on alpha1-antitrypsin (AAT) deficiency, was formed in response to a World Health Organization recommendation. Each of the nearly 20 participating countries maintains a national registry of patients with AAT deficiency and contributes to an international database located in Malmö, Sweden. This database is designed to increase understanding of AAT deficiency. Additionally, AIR members are engaged in active, wide-ranging investigations to improve the diagnosis, monitoring, and treatment of the disease and meet biennially to exchange views and research findings. The fourth biennial meeting was held in Copenhagen, Denmark, on 2-3 June 2005. This review covers the wide range of AAT deficiency-related topics that were addressed encompassing advances in genetic characterization, risk factor identification, clinical epidemiology, inflammatory and signalling processes, therapeutic advances, and lung imaging techniques.

Cryptic haplotypes ofSERPINA1confer susceptibility to chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major cause of mortality and morbidity worldwide. While cigarette smoking is a major cause of COPD, only 15% of smokers develop the disease, indicating major genetic influences. The most widely recognized candidate gene in COPD is SERPINA1, although it has been suggested that SERPINA3 may also play a role. To detect cryptic genetic variants that might contribute to disease, we identified 15 SNP haplotype tags from high-density SNP maps of the two genes and evaluated these SNPs in the largest case-control genetic study of COPD conducted so far. For SERPINA1, six newly identified haplotypes with a common backbone of five SNPs were found to increase the risk of disease by six- to 50-fold, the highest risk of COPD reported to date. In contrast, no haplotype associations for SERPINA3 were identified.

Transforming growth factor beta1 regulates angiotensin II type I receptor gene expression in the extravillous trophoblast cell line SGHPL-4

The angiotensin II type 1 (AT1) receptor, transforming growth factor beta1 (TGFbeta1) and Oncostatin M (OSM) control key pathways that may be important during placentation. Although interactions between them exist in other tissues, trophoblast cells have not been investigated. Extravillous trophoblast cells, SGHPL-4, were stimulated with 10 ng/ml TGFbeta1 +/- 100 ng/ml OSM for 24 h. Real-time PCR showed that AT1 expression increased 2.76-fold [95% confidence interval (CI) = 1-6.74, P = 0.05] in response to TGFbeta1 and 4.21-fold (95% CI = 1.33-11.76, P = 0.03) with TGFbeta1 + OSM. Luciferase reporter gene constructs containing three haplotypes of the 59 flanking region of the AT1 receptor gene were transfected into SGHPL-4 and HepG2 cells and stimulated with 0.1, 1 and 10 ng/ml TGFbeta1 and 50 ng/ml OSM. Responses were dose and cell dependent. Luciferase activity increased in HepG2 cells in response to TGFbeta1 alone or together with OSM (P < 0.001); transcriptional activation differed between AT1 receptor gene haplotypes. In SGHPL-4 cells, luciferase activity was reduced on exposure to low concentrations of TGFbeta1 or high concentrations of TGFbeta1 combined with OSM (P = 0.003); the response was unaffected by haplotype. Interaction between AT1 and TGFbeta1 is a novel observation in trophoblast and suggests new avenues for the study of placentation.

Expression and secretion of alpha1-proteinase inhibitor are regulated by proinflammatory cytokines in human pancreatic islet cells

AIMS/HYPOTHESIS

Alpha1-proteinase inhibitor (alpha1-PI) has been considered a key player in inflammatory processes. In humans, the main production site of alpha1-PI is the liver, but other tissues, including pancreatic islets, also synthesise this molecule. The aims of this study were to assess the islet cell types that produce alpha1-PI, to determine whether alpha1-PI is actually secreted by islet cells, and to assess how its production and/or secretion are regulated.

METHODS

Expression of alpha1-PI in human islet cells was assessed by immunofluorescence, electron microscopy and western blotting. Release of alpha1-PI was analysed by reverse haemolytic plaque assay and ELISA. The effects of cytokines on alpha1-PI synthesis and secretion were tested.

RESULTS

Immunofluorescence showed that alpha and delta cells do express alpha1-PI, whereas beta cells do not. By electron microscopy, we demonstrated a colocalisation of alpha1-PI with glucagon and somatostatin within secretory granules. Immunolabelling also revealed localisation of alpha1-PI within the Golgi apparatus, related vesicles and lysosomal structures. The expression of alpha1-PI in islet cells was also demonstrated by western blotting and ELISA of protein extracts. ELISA and reverse haemolytic plaque assay showed that alpha1-PI is secreted into the culture medium. Treatment of islet cells with IL-1beta and oncostatin M for 4 days increased the production and release of alpha1-PI.

CONCLUSIONS/INTERPRETATION

Our results demonstrate that alpha1-PI is expressed by the alpha and delta cells of human islets, and that proinflammatory cytokines enhance the production and release of this inhibitor.

House dust mite Der p 1 downregulates defenses of the lung by inactivating elastase inhibitors

House dust mites (HDM) are the most common source of aeroallergens and in genetic susceptible individuals can cause symptoms ranging from atopic dermatitis to bronchial asthma. Der p 1, a major target of the human immune responses to HDM, through its enzymatic properties can modulate the adaptive immune system by the cleavage of CD23 and CD25. The consequences of this would be to promote allergic inflammatory responses. Furthermore, by disrupting epithelial tight junctions Der p 1 facilitates the transport of allergen across the epithelium. Here, we report that Der p 1 has additional effects on the innate defense mechanisms of the lung, by inactivating in vitro and ex vivo the elastase inhibitors human (h) alpha1-proteinase inhibitor (h-A1-Pi), mouse (m-), (but not human [h])-SLPI and h-elafin. We confirm that Der p 1 contain both cysteine and serine proteinases, and extend this finding to demonstrate for the first time that h-elafin is particularly sensitive to the biological activity of the latter. Because these elastase inhibitors have antimicrobial, as well as antielastase activity, our results suggest that inactivation of these innate components of the lung defense system by Der p 1 may increase the susceptibility of patients with allergic inflammation to infection.

Neutrophil DNA contributes to the antielastase barrier during acute lung inflammation

During acute lung inflammation, the airspaces are invaded by circulating neutrophils. These may then injure tissues through the release of elastase. Different natural specific inhibitors such as alpha1-proteinase inhibitor, secretory leukocyte proteinase inhibitor, and elafin are nonetheless able to counteract the enzymatic activity of elastase. The present study was undertaken to assess the role of these different inhibitors in the intrinsic antielastase barrier during lipopolysaccharide-induced lung inflammation in mice. Upon intranasal administration of lipopolysaccharide to mice, the antielastase activity recovered from bronchoalveolar lavage fluids (BALF) increases progressively up to 48 h (7-fold) and returns to the basal level within 72 h. By contrast, when the same experiments are performed with neutropenic mice (pretreatment with an antigranulocyte antibody, or vinblastine), the increase is almost totally absent. Ultrafiltration of BALF through 100 kD cutoff membranes shows that the activity remains in the retentate, thus ruling out a role for native alpha1-proteinase inhibitor, secretory leukocyte proteinase inhibitor, and elafin. Gel filtration and fraction analysis show that the material eluted with a Mr of 600 kD. Agarose gel electrophoresis and ethidium bromide staining reveal that the activity corresponds to the presence a large amount of DNA. Interestingly, DNase treatment of the active fraction suppresses the antielastase activity. Analysis of BALF from patients with acute lung inflammation shows the presence of DNA with antielastase activity. We therefore concluded that during acute lung inflammation, the recruitment of neutrophils in the airspaces accounts for the increased presence of DNA, which in turn contributes to the antielastase barrier.

Regulation of haptoglobin secretion by recombinant bovine cytokines in primary cultured bovine hepatocytes

We examined the regulation of haptoglobin (Hp) secretion in primary cultured bovine hepatocytes using recombinant bovine (rb) proinflammatory cytokines. The concentrations of Hp in the supernatant of cultured hepatocytes after incubation with rb interleukin (IL)-6, rb tumor necrosis factor (TNF)-alpha, rbIL-1 beta or rbIFN-gamma alone or with combinations of two of these cytokines were measured by ELISA. The rbIL-6, rbTNF-alpha and rbIL-1 beta increased Hp synthesis, but rbIFN-gamma did not, and rbIL-6 was the most effective Hp inducer among these cytokines. The Hp secretion was accelerated synergistically by combined treatment with rbIL-6 and rbTNF-alpha, whereas it remained unchanged with a combination of rbIL-6 and rbIL-1 beta. In contrast, the combination of rbIL-6 and rbIFN-gamma downregulated Hp secretion. In conclusion, IL-6 is the principal cytokine in Hp secretion in bovine hepatocytes in vitro, and its activity may be regulated by other cytokines.

Effect of fluticasone on the elastase:antielastase profile of the normal lung

BACKGROUND

Excessive elastolytic activity contributes to the pathogenesis of several inflammatory respiratory diseases. The effect of glucocorticoids, which are potent anti-inflammatory agents, on the elastase:antielastase balance of the human respiratory tract is unclear, as studies on patients and in vitro have yielded inconsistent results.

DESIGN

To clarify this, bronchoalveolar lavage and lavage fluids from the upper and central airways were collected from 10 healthy, nonsmoking volunteers before and after a 2-week course of inhaled fluticasone propionate (2 x 500 micrograms day-1). Concentrations of two neutrophil elastase inhibitors, alpha-1-proteinase inhibitor (PI) and secretory leukoproteinase inhibitor (SLPI), as well as neutrophil elastase (NE) activity and NE inhibitory capacity (NEIC) were quantified in all lavage fluids.

RESULTS

Concentrations of SLPI were highest in the proximal airways and decreased distally. Neutrophil elastase inhibitory capacity activity followed the same gradient and correlated positively and consistently with SLPI, suggesting that this inhibitor makes an important contribution to the regulation of elastolytic activity in the healthy human respiratory tract. Inhaled fluticasone propionate had no effect on any component of the elastase:antielastase balance at any level of the respiratory tract, even though circulating cortisol levels were reduced in all subjects, confirming subject compliance and adequate pulmonary delivery of the drug.

CONCLUSION

This lack of action in the respiratory tract may contribute to the ineffectiveness of inhaled glucocorticoids in respiratory conditions characterised by excessive elastolytic activity.

Database of bronchoalveolar lavage fluid proteins

Bronchoalveolar lavage during fiberoptic bronchoscopy is extensively used for investigating cellular and biochemical alterations of the epithelial lining fluid in various lung disorders. Two-dimensional electrophoresis (2-DE) offers the possibility to simultaneously display and analyze proteins contained in bronchoalveolar lavage fluid (BALF). We present the current status of 2-DE of BALF samples with an updated listing of the proteins already identified and of their level and/or posttranslational alterations in lung disorders. Alternatives to 2-DE of BALF samples and future prospects of proteomics to unravel lung functions and pathologies are discussed.

Polymorphonuclear neutrophils are a source of hepatocyte growth factor in patients with severe alcoholic hepatitis

BACKGROUND/AIMS

Hepatocyte growth factor (HGF) is a pleiotropic cytokine involved in liver regeneration. Plasma HGF levels correlate with survival and hepatocyte proliferation in alcoholic hepatitis (AH). As AH is accompanied by inflammation, neutrophilia and polymorphonuclear neutrophil (PMN) infiltration of the liver, we postulated that PMN could be a source of HGF in such patients.

METHODS

We studied 25 patients with severe AH in comparison with 20 alcoholic cirrhotic patients without AH and 20 healthy controls; the impact of a 28-day course of corticosteroids was evaluated in patients with AH.

RESULTS

On day 0, HGF plasma and homogenized liver tissue levels were markedly increased in AH patients as compared to controls. The role of PMN in HGF production during AH was confirmed by a significantly higher ex-vivo HGF production capacity of lipopolysaccharide-stimulated blood PMN from AH patients relative to both control groups. Formyl-Methionyl-Leucyl-Phenylalanine-induced PMN release of HGF (degranulation conditions) was also higher in AH patients. In this setting, we found that HGF release by PMN ex vivo correlated strongly with HGF plasma levels, and that the degree of hepatic PMN correlated strongly with hepatic HGF levels. HGF plasma levels and ex-vivo HGF release by PMN were unaffected by steroid therapy.

CONCLUSIONS

These findings suggest that, by releasing HGF, PMN could participate in liver regeneration during severe alcoholic hepatitis.

Hepatocyte growth factor is produced by blood and alveolar neutrophils in acute respiratory failure

We tested the novel hypothesis that neutrophils in the lung or the airspaces may produce hepatocyte growth factor (HGF) in ventilated patients with acute respiratory failure. Neutrophils were purified from blood and bronchoalveolar lavage (BAL) fluid samples from 16 mechanically ventilated patients who underwent BAL for a diagnostic workup of ventilator-acquired pneumonia. Most of the patients had pneumonia (n = 11). Ten nonventilated patients served as controls. Both blood and BAL neutrophils released HGF in vitro. Basal HGF secretion by blood neutrophils from controls was 823 (666) pg x ml(-1) x 10(-7) neutrophils (median, 25th-75th percentile) and doubled to 1,730 (1,684-2,316) pg x ml(-1) x 10(-7) neutrophils (P = 0.001) with lipopolysaccharide (LPS) stimulation. Basal HGF secretion by blood neutrophils from patients was similar [956 (655-2,140) pg x ml(-1) x 10(-7) neutrophils, P = 0.4] and doubled with LPS stimulation [2,767 (2,165-3,688) pg x ml(-1) x 10(-7) neutrophils, P < 0.0001 vs. controls]. Alveolar neutrophils released HGF in vitro [653 (397-1,209) pg x ml(-1) x 10(-7) neutrophils]. LPS stimulation did not significantly increase the HGF release from alveolar neutrophils [762 (434-1,305) pg x ml(-1) x 10(-7) neutrophils]. BAL HGF positively correlated with the BAL neutrophil count (P = 0.01, R = 0.58). We conclude that blood and alveolar neutrophils from patients with acute respiratory failure can produce HGF, a mitogenic factor that may enhance the alveolar repair process.

Oncostatin M production by blood and alveolar neutrophils during acute lung injury

Polymorphonuclear neutrophils (PMN) are involved in the pathogenesis of acute lung injury (ALI), secreting numerous mediators such as proteases, reactive oxygen species, and cytokines. Because we had recently observed the ability of normal human PMN to degranulate and synthesize oncostatin M (OSM), an IL-6-family cytokine, we quantified OSM production ex vivo by highly purified blood and alveolar PMN from 24 ventilated patients with ALI, including some patients with severe pneumonia. Most of the patients had no detectable OSM in plasma, and OSM production by cultured blood PMN was similar to that of healthy controls. However, OSM was present in bronchoalveolar lavage (BAL) fluid supernatant, with significantly higher levels during pneumonia. In addition, alveolar OSM levels correlated with the number of PMN obtained by BAL, suggesting that PMN are an important source of OSM within the alveoli. Indeed, purified alveolar PMN from all of the patients, especially those with pneumonia, strongly produced OSM. Interestingly, in the latter patients, alveolar PMN always produced more OSM than autologous blood PMN. These results document the functional duality of PMN in ALI by showing the participation of PMN in the modulation of lung inflammation.

Alveolar epithelial type II cell: defender of the alveolus revisited

In 1977, Mason and Williams developed the concept of the alveolar epithelial type II (AE2) cell as a defender of the alveolus. It is well known that AE2 cells synthesise, secrete, and recycle all components of the surfactant that regulates alveolar surface tension in mammalian lungs. AE2 cells influence extracellular surfactant transformation by regulating, for example, pH and [Ca2+] of the hypophase. AE2 cells play various roles in alveolar fluid balance, coagulation/fibrinolysis, and host defence. AE2 cells proliferate, differentiate into AE1 cells, and remove apoptotic AE2 cells by phagocytosis, thus contributing to epithelial repair. AE2 cells may act as immunoregulatory cells. AE2 cells interact with resident and mobile cells, either directly by membrane contact or indirectly via cytokines/growth factors and their receptors, thus representing an integrative unit within the alveolus. Although most data support the concept, the controversy about the character of hyperplastic AE2 cells, reported to synthesise profibrotic factors, proscribes drawing a definite conclusion today.

Human bronchoalveolar lavage fluid: two-dimensional gel electrophoresis, amino acid microsequencing and identification of major proteins

Although bronchoalveolar lavage has been used as a research and clinical tools for more than two decades to investigate the cellular and soluble components of the lower respiratory tract, its exact protein composition has never been established. In this context, proteins of human bronchoalveolar lavage fluids (BALF), obtained by washing the epithelial lining fluid of the lungs with phosphate-buffered saline, were analyzed by two-dimensional electrophoresis (2-DE) under denaturing and reducing conditions. To characterize the widest amount of proteins, an analytical map of human bronchoalveolar lavage fluid proteins has been created from a pool of BALF from various patients. The resulting map comprises 211 silver-stained spots in the range of pI 3.5-10 and molecular mass 5-100 kDa. We identified 182 spots by microsequence analysis and by matching with human blood plasma and the Macrophage Like Cell line reference 2-DE maps available from the SWISS-2DPAGE database. The human bronchoalveolar lavage fluid was found to contain 61 different proteins or isoforms thereof. Most of the proteins had low molecular masses (< 35 kDa) and rather acidic isoelectric points (pI; 4 < pI < 7). The proteins in the lavage either are produced locally or originate from plasma. Two unknown proteins were identified and are currently under investigation.

Oncostatin M Production and Regulation by Human Polymorphonuclear Neutrophils

Oncostatin M (OSM) is an interleukin-6 (IL-6) family cytokine known in particular to induce the synthesis of acute-phase proteins by hepatocytes. Because human polymorphonuclear neutrophils (PMN) can secrete numerous cytokines, the potential production of OSM by PMN was investigated. Highly purified PMN were found to contain an intracellular stock of preformed OSM that was rapidly mobilized by degranulating agents such as phorbol myristate acetate and granulocyte-macrophage colony-stimulating factor (GM-CSF). Moreover, PMN produced OSM after a few hours of stimulation by various agonists. The most potent effect was observed with the combination of lipopolysaccharide and GM-CSF, which had a concentration- and time-dependent effect at both the protein and mRNA levels. Actinomycin D strongly reduced OSM mRNA induction, suggesting the involvement of gene transcription. Cycloheximide inhibited OSM protein synthesis but did not affect the release of preformed stores. In addition, OSM production was downregulated by dexamethasone, whereas IL-10 had no effect. The OSM produced by PMN was biologically active, as demonstrated by its ability to induce 1-acid glycoprotein synthesis by HepG2 cells. OSM secretion thus occurs through a two-step mechanism in PMN, consisting of early release of a preformed stock, followed by de novo protein synthesis. This would allow rapid and sustained OSM release to occur at inflammatory sites, and may contribute to the modulation of local inflammation.

Oncostatin M Production and Regulation by Human Polymorphonuclear Neutrophils

Oncostatin M (OSM) is an interleukin-6 (IL-6) family cytokine known in particular to induce the synthesis of acute-phase proteins by hepatocytes. Because human polymorphonuclear neutrophils (PMN) can secrete numerous cytokines, the potential production of OSM by PMN was investigated. Highly purified PMN were found to contain an intracellular stock of preformed OSM that was rapidly mobilized by degranulating agents such as phorbol myristate acetate and granulocyte-macrophage colony-stimulating factor (GM-CSF). Moreover, PMN produced OSM after a few hours of stimulation by various agonists. The most potent effect was observed with the combination of lipopolysaccharide and GM-CSF, which had a concentration- and time-dependent effect at both the protein and mRNA levels. Actinomycin D strongly reduced OSM mRNA induction, suggesting the involvement of gene transcription. Cycloheximide inhibited OSM protein synthesis but did not affect the release of preformed stores. In addition, OSM production was downregulated by dexamethasone, whereas IL-10 had no effect. The OSM produced by PMN was biologically active, as demonstrated by its ability to induce 1-acid glycoprotein synthesis by HepG2 cells. OSM secretion thus occurs through a two-step mechanism in PMN, consisting of early release of a preformed stock, followed by de novo protein synthesis. This would allow rapid and sustained OSM release to occur at inflammatory sites, and may contribute to the modulation of local inflammation.