Soluble CD14 acts as a DAMP in human macrophages: origin and involvement in inflammatory cytokine/chemokine production.

The innate immune system is able to detect bacterial LPS through the pattern recognition receptor CD14, which delivers LPS to various TLR signaling complexes that subsequently induce intracellular proinflammatory signaling cascades. In a previous study, we showed the overproduction of the soluble form of CD14 (sCD14) by macrophages from patients with cystic fibrosis (CF). CF is an autosomal recessive disorder that is caused by mutations in the gene that encodes the CFTR protein and is characterized by persistent inflammation. Macrophages play a significant role in the initial stages of this disease due to their inability to act as suppressor cells, leading to chronic inflammation in CF. In this work, we investigated the origin of sCD14 by human macrophages and studied the effect of sCD14 on the production of inflammatory cytokine/chemokine. Our data indicate that sCD14 stimulate proinflammatory cytokine/chemokine production in a manner that is independent of LPS but dependent on the TLR-4/CD14 membrane complex, NF-κB, and the inflammasome. Therefore, sCD14, overproduced by CF macrophages, originates primarily from the endocytosis/exocytosis process and should be considered to be a danger-associated molecular pattern. This elucidation of the origin and inflammation-induced mechanisms associated with sCD14 contributes to our understanding of maintained tissue inflammation.-Lévêque, M., Simonin-Le Jeune, K., Jouneau, S., Moulis, S., Desrues, B., Belleguic, C., Brinchault, G., Le Trionnaire, S., Gangneux, J.-P., Dimanche-Boitrel, M.-T., Martin-Chouly, C. Soluble CD14 acts as a DAMP in human macrophages: origin and involvement in inflammatory cytokine/chemokine production.

Assessment of endocrine disruptor impacts on lipid metabolism in a fatty acid-supplemented HepaRG human hepatic cell line.

The incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. This disease encompasses several stages, from steatosis to steatohepatitis and, eventually, to fibrosis and cirrhosis. Exposure to environmental contaminants is one of the risk factors and an increasing amount of evidence points to a role for endocrine disrupting compounds (EDCs). This study assesses the impact of selected EDCs on the formation of lipid droplets, the marker for steatosis in a hepatic model. The mechanisms underlying this effect are then explored. Ten compounds were selected according to their obesogenic properties: bisphenol A, F and S, butyl-paraben, cadmium chloride, p,p'-DDE, DBP, DEHP, PFOA and PFOS. Using a 2D or 3D model, HepaRG cells were exposed to the compounds with or without fatty acid supplementation. Then, the formation of lipid droplets was quantified by an automated fluorescence-based method. The expression of genes and proteins involved in lipid metabolism and the impact on cellular respiration was analyzed. The formation of lipid droplets, which is revealed or enhanced by oleic acid supplementation, was most effectively induced by p,p'-DDE and DEHP. Experiments employing either 2D or 3D culture conditions gave similar results. Both compounds induced the expression of PLIN2. p,p'-DDE also appears to act by decreasing in fatty acid oxidation. Some EDCs were able to induce the formation of lipid droplets, in HepaRG cells, an effect which was increased after supplementation of the cells with oleic acid. A full understanding of the mechanisms of these effects will require further investigation. The novel automated detection method described here may also be useful in the future as a regulatory test for EDC risk assessment.

Obesity III: Obesogen assays: Limitations, strengths, and new directions.

There is increasing evidence of a role for environmental contaminants in disrupting metabolic health in both humans and animals. Despite a growing need for well-understood models for evaluating adipogenic and potential obesogenic contaminants, there has been a reliance on decades-old in vitro models that have not been appropriately managed by cell line providers. There has been a quick rise in available in vitro models in the last ten years, including commercial availability of human mesenchymal stem cell and preadipocyte models; these models require more comprehensive validation but demonstrate real promise in improved translation to human metabolic health. There is also progress in developing three-dimensional and co-culture techniques that allow for the interrogation of a more physiologically relevant state. While diverse rodent models exist for evaluating putative obesogenic and/or adipogenic chemicals in a physiologically relevant context, increasing capabilities have been identified for alternative model organisms such as Drosophila, C. elegans, zebrafish, and medaka in metabolic health testing. These models have several appreciable advantages, including most notably their size, rapid development, large brood sizes, and ease of high-resolution lipid accumulation imaging throughout the organisms. They are anticipated to expand the capabilities of metabolic health research, particularly when coupled with emerging obesogen evaluation techniques as described herein.

Combinatorial pathway disruption is a powerful approach to delineate metabolic impacts of endocrine disruptors.

The prevalence of metabolic diseases, such as obesity, diabetes, metabolic syndrome and chronic liver diseases among others, has been rising for several years. Epidemiology and mechanistic (in vivo, in vitro and in silico) toxicology have recently provided compelling evidence implicating the chemical environment in the pathogenesis of these diseases. In this review, we will describe the biological processes that contribute to the development of metabolic diseases targeted by metabolic disruptors, and will propose an integrated pathophysiological vision of their effects on several organs. With regard to these pathomechanisms, we will discuss the needs, and the stakes of evolving the testing and assessment of endocrine disruptors to improve the prevention and management of metabolic diseases that have become a global epidemic since the end of last century.

Obesity II: Establishing causal links between chemical exposures and obesity.

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Global effects of inorganic arsenic on gene expression profile in human macrophages.

Inorganic arsenic, a major environmental contaminant, exerts immunosuppressive effects towards human cells. We previously demonstrated that relevant environmental concentrations of inorganic arsenic altered morphology and functions of human primary macrophages, suggesting interference with macrophage differentiation program. The goal of this study was to determine global effect of low concentrations of arsenic trioxide (As(2)O(3)) on gene expression profile in human primary macrophages, in order to identify molecular targets of inorganic arsenic, especially those relevant of macrophage differentiation process. Using a pan-genomic microarray, we demonstrate that exposure of human blood monocyte-derived macrophages to 1microM As(2)O(3) for 72h, a non-cytototoxic concentration, results in up-regulation of 32 genes and repression of 91 genes. Among these genes, 26 are specifically related to differentiation program of human macrophages. Particularly, we validated that As(2)O(3) strongly alters expression of MMP9, MMP12, CCL22, SPON2 and CXCL2 genes, which contribute to major macrophagic functions. Most of these metalloid effects were reversed when As(2)O(3)-treated macrophages were next cultured in arsenic-free medium. We also show that As(2)O(3) similarly regulates expression of this macrophagic gene subset in human alveolar macrophages, the phenotype of which closely resembles that of blood monocyte-derived macrophage. In conclusion, our study demonstrates that environmentally relevant concentrations of As(2)O(3) impair expression of macrophage-specific genes, which fully supports interference of metalloid with differentiation program of human macrophages.

MEHP/ethanol co-exposure favors the death of steatotic hepatocytes, possibly through CYP4A and ADH involvement.

Liver steatosis has been associated with various etiological factors (obesity, alcohol, environmental contaminants). How those factors work together to induce steatosis progression is still scarcely evaluated. Here, we tested whether phthalates could potentiate death of steatotic hepatocytes when combined with ethanol. Pre-steatotic WIF-B9 hepatocytes were co-exposed to mono (2-ethylhexyl) (MEHP, 500 nM; main metabolite of di (2-ethylhexyl) phthalate or DEHP) and ethanol (5 mM) for 5 days. An increased apoptotic death was detected, involving a DNA damage response. Using 4-Methypyrazole to inhibit ethanol metabolism, and CH-223191 to antagonize the AhR receptor, we found that an AhR-dependent increase in alcohol dehydrogenase (ADH) activity was essential for cell death upon MEHP/ethanol co-exposure. Toxicity was also prevented by HET0016 to inhibit the cytochrome P450 4A (CYP4A). Using the antioxidant thiourea, a role for oxidative stress was uncovered, notably triggering DNA damage. Finally, co-exposing the in vivo steatosis model of high fat diet (HFD)-zebrafish larvae to DEHP (2.56 nM)/ethanol (43 mM), induced the pathological progression of liver steatosis alongside an increased Cyp4t8 (human CYP4A homolog) mRNA expression. Altogether, these results further emphasized the deleterious impact of co-exposures to ethanol/environmental pollutant towards steatosis pathological progression, and unraveled a key role for ADH and CYP4A in such effects.

MiR-146a is over-expressed and controls IL-6 production in cystic fibrosis macrophages.

Cystic fibrosis (CF) is an inherited disease that is characterised by susceptibility to bacterial infections and chronic lung inflammation. Recently, it was suggested that macrophages contribute to impaired host defence and excessive inflammatory responses in CF. Indeed, dysfunction attributed to CF macrophages includes decreased bacterial killing and exaggerated inflammatory responses. However, the mechanisms behind such defects have only been partially defined. MicroRNAs (miRNAs) have emerged as key regulators of several macrophage functions, including their activation, differentiation and polarisation. The goal of this study was to investigate whether miRNA dysregulation underlies the functional abnormalities of CF macrophages. MiRNA profiling of macrophages was performed, with 22 miRNAs identified as differentially expressed between CF and non-CF individuals. Among these, miR-146a was associated with significant enrichment of validated target genes involved in responses to microorganisms and inflammation. As miR-146a dysregulation has been reported in several human inflammatory diseases, we analysed the impact of increased miR-146a expression on inflammatory responses of CF macrophages. These data show that inhibition of miR-146a in lipopolysaccharide-stimulated CF macrophages results in increased interleukin-6 production, which suggests that miR-146a overexpression in CF is functional, to restrict inflammatory responses.

Low interleukin-10 release after ex vivo stimulation of whole blood is associated with persistent organ dysfunction in sepsis: A prospective observational study.

BACKGROUND: Sepsis profoundly alters immune homeostasis. Cytokine release after whole blood lipopolysaccharide (LPS)-stimulation reflects cell function across multiple immune cell classes and represents the immune response to LPS. The main goal of this study was to evaluate the prognostic value of ex vivo stimulation of whole blood with LPS in sepsis. METHODS: Blood was drawn on day 1 and day 7 after admission, and stimulated ex vivo with LPS. Tumour necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6 and IL-10 were measured with and without stimulation. Our primary outcome measure was the persistence of at least one organ dysfunction at day 7. Organ dysfunction was defined according to the SOFA components by a score ≥ 2. RESULTS: Forty-nine patients with sepsis from a 21-bed intensive care unit, and 23 healthy volunteers were enrolled. The blood of septic patients was less responsive to ex vivo stimulation with LPS than that of healthy controls at day 1 and 7, as demonstrated by lower TNF-α, IL-1ß, IL-6 and IL-10 release. Persistent organ dysfunction was more frequent in patients with lower IL-10 release at day 1 but such an association was not found for pro-inflammatory cytokines. A persistent low IL-10 release at day 7 was also associated with persistent organ dysfunction. CONCLUSION: These data suggest that the capacity to produce IL-10 in response to whole blood ex vivo stimulation early in sepsis, as well as persistent low IL-10 response over time, may help in prognostication and patient stratification. These results will need to be confirmed in future studies.

Phagocytosis depends on TRPV2-mediated calcium influx and requires TRPV2 in lipids rafts: alteration in macrophages from patients with cystic fibrosis.

Whereas many phagocytosis steps involve ionic fluxes, the underlying ion channels remain poorly defined. As reported in mice, the calcium conducting TRPV2 channel impacts the phagocytic process. Macrophage phagocytosis is critical for defense against pathogens. In cystic fibrosis (CF), macrophages have lost their capacity to act as suppressor cells and thus play a significant role in the initiating stages leading to chronic inflammation/infection. In a previous study, we demonstrated that impaired function of CF macrophages is due to a deficient phagocytosis. The aim of the present study was to investigate TRPV2 role in the phagocytosis capacity of healthy primary human macrophage by studying its activity, its membrane localization and its recruitment in lipid rafts. In primary human macrophages, we showed that P. aeruginosa recruits TRPV2 channels at the cell surface and induced a calcium influx required for bacterial phagocytosis. We presently demonstrate that to be functional and play a role in phagocytosis, TRPV2 might require a preferential localization in lipid rafts. Furthermore, CF macrophage displays a perturbed calcium homeostasis due to a defect in TRPV2. In this context, deregulated TRPV2-signaling in CF macrophages could explain their defective phagocytosis capacity that contribute to the maintenance of chronic infection.

The impact of impaired macrophage functions in cystic fibrosis disease progression.

The underlying cause of morbidity in cystic fibrosis (CF) is the decline in lung function, which results in part from chronic inflammation. Inflammation and infection occur early in infancy in CF and the role of innate immune defense in CF has been highlighted in the last years. Once thought simply to be consumers of bacteria, macrophages have emerged as highly sensitive immune cells that are located at the balance point between inflammation and resolution of this inflammation in CF pathophysiology. In order to assess the potential role of macrophage in CF, we review the evidence that: (1) CF macrophage has a dysregulated inflammatory phenotype; (2) CF macrophage presents altered phagocytosis capacity and bacterial killing; and (3) lipid disorders in CF macrophage affect its function. These alterations of macrophage weaken innate defense of CF patients and may be involved in CF disease progression and lung damage.

Modulation of matrix metalloproteinase production from human lung fibroblasts by type 4 phosphodiesterase inhibitors.

Over-expression of matrix metalloproteinases by lung fibroblasts has been blamed for much of the tissue destruction associated with airway inflammation. Because cyclic AMP is known to regulate fibroblast proliferation, as well as cytokine and extracellular matrix protein production, the current study was designed to evaluate the ability of three selective phosphodiesterase (PDE) type 4 inhibitors, rolipram, cilomilast and CI-1044, to inhibit extracellular matrix degradation. Using zymography and ELISA, we found that pro-MMP-2 release was enhanced following 24 h treatment of human lung fibroblast (MRC-5) with TGF-beta1 (10 ng/ml) or TNF-alpha (10 ng/ml), whereas PMA (0.02 microM) had no effect. One hour of pre-incubation with PDE4 inhibitors (10 microM) induced an inhibition of TNF-alpha-stimulated pro-MMP-2 release. Zymography and immunoblotting revealed that fibroblasts cultured with PMA or TNF-alpha released increased amounts of pro-MMP-1, whereas TGF-beta1 had no effect. Incubation with CI-1044 or cilomilast significantly prevented the TNF-alpha increase in pro-MMP-1. These results suggest that PDE4 inhibitors are effective in inhibiting the pro-MMP-2 and pro-MMP-1 secretion induced by TNF-alpha and might underline a potential therapeutic benefit of selective PDE4 inhibitors in lung diseases associated with abnormal tissue remodelling.

Solid-phase synthesis and evaluation of libraries of substituted 4,5-dihydropyridazinones as vasodilator agents.

The solid-phase parallel preparation of a library of 4,5-dihydropyridazin-3(2H)-one derivatives substituted at position 6 with piperazinylmethyl or tetrahydroquinolinylmethyl groups and analogues (3) is reported. Polymer-supported gamma-keto-delta-aminoesters prepared from Wang resin reacted with hydrazine or methylhydrazine to afford pyridazinones in good yields after a cyclization cleavage approach. We have evaluated these novel analogues and several compounds of other series (1, 2) for their vasorelaxant effect. Among the products tested, 3l and 3d proved to be efficacious and potent relaxant agents of the isolated rat aorta. Inhibitors of phosphodiesterase (PDE3), responsible for the breakdown of cyclic AMP in the vascular smooth muscle, are currently developed for cardiac heart failure because of their inotropic effect and coronary vasodilatation. We had expected that the vasodilatation induced by 3l, as efficient as reference PDE3 inhibitors, milrinone or CI-930, to be due to PDE3 inhibition. However 3l and 3d exhibited a low inhibitory effect against PDE3 isoenzyme activity. These compounds induced a significant vasorelaxation, which could be of therapeutic interest even if their mechanism of action remains to be determined.

Impaired functions of macrophage from cystic fibrosis patients: CD11b, TLR-5 decrease and sCD14, inflammatory cytokines increase.

BACKGROUND: Early in life, cystic fibrosis (CF) patients are infected with microorganisms. The role of macrophages has largely been underestimated in literature, whereas the focus being mostly on neutrophils and epithelial cells. Macrophages may however play a significant role in the initiating stages of this disease, via an inability to act as a suppressor cell. Yet macrophage dysfunction may be the first step in cascade of events leading to chronic inflammation/infection in CF. Moreover, reports have suggested that CFTR contribute to altered inflammatory response in CF by modification of normal macrophage functions. OBJECTIVES: In order to highlight possible intrinsic macrophage defects due to impaired CFTR, we have studied inflammatory cytokines secretions, recognition of pathogens and phagocytosis in peripheral blood monocyte-derived macrophages from stable adult CF patients and healthy subjects (non-CF). RESULTS: In CF macrophage supernatants, concentrations of sCD14, IL-1ß, IL-6, TNF-α and IL-10 were strongly raised. Furthermore expression of CD11b and TLR-5 were sorely decreased on CF macrophages. Beside, no difference was observed for mCD14, CD16, CD64, TLR-4 and TLR1/TLR-2 expressions. Moreover, a strong inhibition of phagocytosis was observed for CF macrophages. Elsewhere CFTR inhibition in non-CF macrophages also led to alterations of phagocytosis function as well as CD11b expression. CONCLUSIONS: Altogether, these findings demonstrate excessive inflammation in CF macrophages, characterized by overproduction of sCD14 and inflammatory cytokines, with decreased expression of CD11b and TLR-5, and impaired phagocytosis. This leads to altered clearance of pathogens and non-resolution of infection by CF macrophages, thereby inducing an exaggerated pro-inflammatory response.

Inorganic arsenic alters expression of immune and stress response genes in activated primary human T lymphocytes.

Inorganic arsenic, a carcinogenic environmental contaminant, exerts immunosuppressive effects on human T lymphocytes. In particular, interleukin-2 (IL2) secretion and T cell proliferation are reduced when peripheral blood mononuclear cells (PBMC) from individuals chronically exposed to arsenic are stimulated ex vivo with lectins such as phytohemaglutinin (PHA). However, it is not clear whether the metalloid directly acts on T cells or blocks monocyte-dependent accessory signals activated by PHA. We report that in vitro pre-treatment of PBMC with sodium arsenite (NaAs) reduces IL2 secretion and T cell proliferation induced by PHA, but does not prevent expression of monocyte-derived cytokines (IL1, IL6, TNFα) functioning as lymphocyte-activating factors. In addition, we found that NaAs delays induction of IL2 and IL2 receptor α chain (IL2RA) mRNA levels in human primary isolated T cells activated by PHA. Kinetic analysis showed that NaAs pre-treatment first inhibits, but thereafter markedly increases, induction of IL2 and IL2RA mRNA when T cells are stimulated with PHA for 8 h and 72 h, respectively. We conducted whole genome microarray-based analysis of gene expression in primary T cell cultures derived from independent donors. NaAs systematically and significantly up-regulated a set of 35 genes, including several immune and stress genes, such as IL13, granulocyte-macrophage colony stimulating factor, lymphotoxin α and heme oxygenase-1 (HO-1). Up-regulation of HO-1, a stress and immunosuppressive protein, was rapidly detectable, both in T cells and in PBMC treated with NaAs. Inhibition of the immunosuppressive activity of HO-1 in PBMC however failed to prevent NaAs-dependent inhibition of T cell proliferation induced by PHA. Our findings demonstrate that, at least in vitro, inorganic arsenic acts directly on human T cells and impairs their activity, probably independently of HO-1 expression and monocyte-related accessory signals.

Anti-inflammatory effect of fluvastatin on IL-8 production induced by Pseudomonas aeruginosa and Aspergillus fumigatus antigens in cystic fibrosis.

BACKGROUND: Early in life, patients with cystic fibrosis (CF) are infected with microorganisms including bacteria and fungi, particularly Pseudomonas aeruginosa and Aspergillus fumigatus. Since recent research has identified the anti-inflammatory properties of statins (besides their lipid-lowering effects), we investigated the effect of fluvastatin on the production of the potent neutrophil chemoattractant chemokine, IL-8, in whole blood from CF patients, stimulated by Pseudomonas aeruginosa (LPS) and Aspergillus fumigatus (AFA) antigens. RESULTS: Whole blood from adult patients with CF and from healthy volunteers was collected at the Rennes University Hospital (France). Blood was pretreated for 1 h with fluvastatin (0-300 µM) and incubated for 24 h with LPS (10 µg/mL) and/or AFA (diluted 1/200). IL-8 protein levels, quantified by ELISA, were increased in a concentration-dependent manner when cells were stimulated by LPS or AFA. Fluvastatin strongly decreased the levels of IL-8, in a concentration-dependent manner, in whole blood from CF patients. However, its inhibitory effect was decreased or absent in whole blood from healthy subjects. Furthermore, the inhibition induced by fluvastatin in CF whole blood was reversed in the presence of intermediates within the cholesterol biosynthesis pathway, mevalonate, farnesyl pyprophosphate or geranylgeranyl pyrophosphate that activate small GTPases by isoprenylation. CONCLUSIONS: For the first time, the inhibitory effects of fluvastatin on CF systemic inflammation may reveal the important therapeutic potential of statins in pathological conditions associated with the over-production of pro-inflammatory cytokines and chemokines as observed during the manifestation of CF. The anti-inflammatory effect could be related to the modulation of the prenylation of signalling proteins.

Increased extracellular matrix metalloproteinase inducer (EMMPRIN) expression in pulmonary fibrosis.

Extracellular matrix metalloproteinase inducer (EMMPRIN) was examined on bronchoalveolar lavage fluids (BALFs) and lung tissue from patients with fibrosis (usual interstitial pneumonia-idiopathic pulmonary fibrosis [UIP-IPF], n = 15; diffuse parenchymal lung diseases without IPF characteristics on computerized tomography scan, n = 8) and without fibrosis (n = 6). In UIP-IPF, EMMPRIN staining was increased in areas of fibrosis, mainly in macrophages and in epithelial cells. EMMPRIN was also found in the extracellular medium with significant levels in patients with lung fibrosis compared to subjects without fibrosis. Moreover, macrophages from patients with lung fibrosis spontaneously produce EMMPRIN. These findings show that EMMPRIN is increased in lung fibrosis.

Selective PDE4 inhibitors as potent anti-inflammatory drugs for the treatment of airway diseases.

Phosphodiesterases (PDEs) are responsible for the breakdown of intracellular cyclic nucleotides, from which PDE4 are the major cyclic AMP metabolizing isoenzymes found in inflammatory and immune cells. This generated greatest interest on PDE4 as a potential target to treat lung inflammatory diseases. For example, cigarette smoke-induced neutrophilia in BAL was dose and time dependently reduced by cilomilast. Beside the undesired side effects associated with the first generation of PDE4 inhibitors, the second generation of selective inhibitors such as cilomilast and roflumilast showed clinical efficacy in asthma and chronic obstructive pulmonary diseases trials, thus re-enhancing the interest on these classes of compounds. However, the ability of PDE4 inhibitors to prevent or modulate the airway remodelling remains relatively unexplored. We demonstrated that selective PDE4 inhibitor RP 73-401 reduced matrix metalloproteinase (MMP)-9 activity and TGF-beta1 release during LPS-induced lung injury in mice and that CI-1044 inhibited the production of MMP-1 and MMP-2 from human lung fibroblasts stimulated by pro-inflammatory cytokines. Since inflammatory diseases of the bronchial airways are associated with destruction of normal tissue structure, our data suggest a therapeutic benefit for PDE4 inhibitors in tissue remodelling associated with chronic lung diseases.