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Across the world, many commercial poultry flocks and captive birds are threatened by infection with Aspergillus fumigatus. Susceptibility to aspergillosis varies among birds; among galliform birds specifically, morbidity and mortality rates seem to be greater in turkeys than in chickens. Little is known regarding the features of avian immune responses after inhalation of Aspergillus conidia, and to date, scarce information on inflammatory responses during aspergillosis exists. Thus, in the present study, we aimed to improve our understanding of the interactions between A. fumigatus and economically relevant galliform birds in terms of local innate immune responses. Intra-tracheal aerosolization of A. fumigatus conidia in turkey and chicken poults led to more severe clinical signs and lung lesions in turkeys, but leukocyte recovery from lung lavages was higher in chickens at 1dpi only. Interestingly, only chicken CD8+ T lymphocyte proportions increased after infection. Furthermore, the lungs of infected chickens showed an early upregulation of pro-inflammatory cytokines, including IL-1β, IFN-γ and IL-6, whereas in turkeys, most of these cytokines showed a downregulation or a delayed upregulation. These results confirmed the importance of an early pro-inflammatory response to ensure the development of an appropriate anti-fungal immunity to avoid Aspergillus dissemination in the respiratory tract. In conclusion, we show for the first time that differences in local innate immune responses between chickens and turkeys during aspergillosis may determine the outcome of the disease. Lay summary Aspergillus fumigatus infection may cause mortality in poultry, depending on species sensitivity. This study confirms the earlier activation of chickens' pro-inflammatory effectors to control Aspergillus dissemination, whereas turkeys' immune response enables the exacerbation of lung lesions.

The potential of herbal extracts containing bioactive compounds to strengthen immunity could contribute to reducing antimicrobial use in poultry. This study aimed at developing a reliable and robust methodological pipeline to assess the ability of herbal extracts to strengthen chicken innate defenses, especially concerning inflammation and oxidative stress. This methodology was applied to Melissa officinalis L. (MEL) extract, recognized for its biological activities including antioxidant and anti-inflammatory properties. Different methods were used to (1). guarantee the quality of MEL extract and its capacity to stimulate the innate immune system; (2). evaluate the relevance of an ex vivo model to mimic inflammatory and oxidative stress challenges to replace LPS injection in chickens; (3). analyse the effects of feed supplemented with MEL extract on inflammation and oxidative stress induced ex vivo; (4). assess the effects of MEL extract on the redox balance, health, welfare and performance in broilers exposed to suboptimal starting conditions through a large-scale approach. The quality of MEL extract preparations, through phytochemical quantification of rosmarinic acid (RA), revealed varying concentrations of RA in the different MEL extracts. RA concentrations remained stable for at least 9 months and in feed three months after incorporating MEL extract. When incubated with chicken cell lines MEL extract showed potential metabolic activation and ability to stimulate immune functions but induced cytotoxicity at high concentrations. The original ex vivo model of inflammation developed on chicken blood cells enabled inflammation and oxidative stress biomarkers to be expressed and revealed antioxidative and anti-inflammatory properties of blood cells from chickens fed MEL extract. The experimental model of chicken suboptimal starting conditions validated beneficial effects of MEL extract on the redox balance and also evidenced improved performance during the growth phase, a tendency for fewer muscle defects but a higher severity of pododermatitis lesions without affecting other welfare indicators. This study grouped methods and tools that could be combined according to the plant extract, the needs of professionals working in poultry production systems and staff responsible for animal health, welfare and feeding.

International audience; Coccidiosis is a disease caused by Eimeria, which represents the first parasitic disease in poultry farming. Among them, E. tenella is a virulent species which specifically colonizes the caecum. The inflammatory response to infection is associated to numerous host proteases including cysteine cathepsins that can be deleterious for tissue and innate immunity integrity. Here, germ-free and conventional chickens were used as models to find out whether the microbiota could modify the intestinal expression of host cysteine cathepsins during coccidiosis. The basal caecal peptidase activity primarily relies on host proteases rather than proteases from the commensal flora. While mRNA levels of E. tenella cathepsins B and L remained unchanged in germ-free and conventional broilers, an overall increase in endopeptidase activity of cysteine cathepsins was found in E. tenella-infected caeca in both experimental models (P < 0.005). A significant decrease in avian cystatin C transcription was also observed in infected conventional, but not in infected germ-free broilers. Despite an unchanged mRNA level of avian cathepsin L (CatL), its protein expression raised following infection, in parallel with an increased transcription of antimicrobial β-defensins (AvBD1, AvBD2, AvBD4, AvBD6, and AvBD7). Taken together, data support that host CatL is post-translationally upregulated during E. tenella infection, and thus may be involved in the alteration of the gut proteolytic balance. Furthermore, CatL may participate to inflammation occurring during coccidiosis through its known ability to proteolytically inactivates up-regulated avian β-defensins that are key molecules of innate immunity.

The anti-viral immune response is dependent on the ability of infected cells to sense foreign nucleic acids. In multiple species, the pattern recognition receptor (PRR) cyclic GMP-AMP synthase (cGAS) senses viral DNA as an essential component of the innate response. cGAS initiates a range of signalling outputs that are dependent on generation of the second messenger cGAMP that binds to the adaptor protein stimulator of interferon genes (STING). Here we show that in chicken macrophages, the cGAS/STING pathway is essential not only for the production of type-I interferons in response to intracellular DNA stimulation, but also for regulation of macrophage effector functions including the expression of MHC-II and co-stimulatory molecules. In the context of fowlpox, an avian DNA virus infection, the cGAS/STING pathway was found to be responsible for type-I interferon production and MHC-II transcription. The sensing of fowlpox virus DNA is therefore essential for mounting an anti-viral response in chicken cells and for regulation of a specific set of macrophage effector functions.

Coccidiosis is a widespread intestinal disease of poultry caused by a parasite of the genus Eimeria. Eimeria tenella, is one of the most virulent species that specifically colonizes the caeca, an organ which harbors a rich and complex microbiota. Our objective was to study the impact of the intestinal microbiota on parasite infection and development using an original model of germ-free broilers. We observed that germ-free chickens presented significantly much lower load of oocysts in caecal contents than conventional chickens. This decrease in parasite load was measurable in caecal tissue by RT-qPCR at early time points. Histological analysis revealed the presence of much less first (day 2pi) and second generation schizonts (day 3.5pi) in germ-free chickens than conventional chickens. Indeed, at day 3.5pi, second generation schizonts were respectively immature only in germ-free chickens suggesting a lengthening of the asexual phase of the parasite in the absence of microbiota. Accordingly to the consequence of this lengthening, a delay in specific gamete gene expressions, and a reduction of gamete detection by histological analysis in caeca of germ-free chickens were observed. These differences in parasite load might result from an initial reduction of the excystation efficiency of the parasite in the gut of germ-free chickens. However, as bile salts involved in the excystation step led to an even higher excystation efficiency in germ-free compared to conventional chickens, this result could not explain the difference in parasite load. Interestingly, when we shunted the excystation step in vivo by infecting chickens with sporozoites using the cloacal route of inoculation, parasite invasion was similar in germ-free and in conventional chickens but still resulted in significantly lower parasite load in germ-free chickens at day 7pi. Overall, these data highlighted that the absence of intestinal microbiota alters E. tenella replication. Strategies to modulate the microbiota and/or its metabolites could therefore be an alternative approach to limit the negative impact of coccidiosis in poultry.

The avian respiratory tract is a common entry route for many pathogens and an important delivery route for vaccination in the poultry industry. Immune responses in the avian lung have mostly been studied in vivo due to the lack of robust, relevant in vitro and ex vivo models mimicking the microenvironment. Precision-cut lung slices (PCLS) have the major advantages of maintaining the 3-dimensional architecture of the lung and includes heterogeneous cell populations. PCLS have been obtained from a number of mammalian species and from chicken embryos. However, as the embryonic lung is physiologically undifferentiated and immunologically immature, it is less suitable to examine complex host–pathogen interactions including antimicrobial responses. Here we prepared PCLS from immunologically mature chicken lungs, tested different culture conditions, and found that serum supplementation has a detrimental effect on the quality of PCLS. Viable cells in PCLS remained present for ≥ 40 days, as determined by viability assays and sustained motility of fluorescent mononuclear phagocytic cells. The PCLS were responsive to lipopolysaccharide stimulation, which induced the release of nitric oxide, IL-1β, type I interferons and IL-10. Mononuclear phagocytes within the tissue maintained phagocytic activity, with live cell imaging capturing interactions with latex beads and an avian pathogenic Escherichia coli strain. Finally, the PCLS were also shown to be permissive to infection with low pathogenic avian influenza viruses. Taken together, immunologically mature chicken PCLS provide a suitable model to simulate live organ responsiveness and cell dynamics, which can be readily exploited to examine host–pathogen interactions and inflammatory responses.

The integrated innate immune features of the calcareous egg and its contents are a critical underpinning of the remarkable evolutionary success of the Aves clade. Beginning at the time of laying, the initial protective structures of the egg, i.e., the biomineralized eggshell, egg-white antimicrobial peptides, and vitelline membrane, are rapidly and dramatically altered during embryonic development. The embryo-generated extra-embryonic tissues (chorioallantoic/amniotic membranes, yolk sac, and associated chambers) are all critical to counteract degradation of primary egg defenses during development. With a focus on the chick embryo (Gallus gallus domesticus), this review describes the progressive transformation of egg innate immunity by embryo-generated structures and mechanisms over the 21-day course of egg incubation, and also discusses the critical interplay between autonomous development and maternal anticipation.

International audience; The aim of this study was to investigate the contribution of IL-33/ST2 axis in the onset and progression of acute liver injury using a mice model of drug-induced liver injury (DILI). DILI was induced by overdose administration of acetaminophen (APAP) by oral gavage in wild-type BALB/c, ST2-deficient mice and in different bone marrow chimeras. Neutrophils were depleted by anti-Ly6G and macrophages with clodronate liposomes (CLL). Blood and liver were collected for biochemical, immunologic and genetic analyses. Mice were imaged by confocal intravital microscopy and liver non-parenchymal cells and hepatocytes were isolated for flow cytometry, genetic and immunofluorescence studies. Acetaminophen overdose caused a massive necrosis and accumulation of immune cells within the liver, concomitantly with IL-33 and chemokine release. Liver non-parenchymal cells were the major sensors for IL-33, and amongst them, neutrophils were the major players in amplification of the inflammatory response triggered by IL-33/ST2 signalling pathway. Blockage of IL-33/ST2 axis reduces APAP-mediated organ injury by dampening liver chemokine release and activation of resident and infiltrating liver non-parenchymal cells.

International audience; The excessive inflammation often present in patients with severe dengue infection is considered both a hallmark of disease and a target for potential treatments. IL-33 is a pleiotropic cytokine with pro-inflammatory effects whose role in dengue has not been fully elucidated. Here we demonstrate that IL-33 plays a disease-exacerbating role during experimental dengue infection in immunocompetent mice. Mice infected with Dengue virus serotype 2 (DENV2) produced high levels of IL-33. DENV2-infected mice treated with recombinant IL-33 developed markedly more severe disease compared to untreated mice as assessed by mortality, granulocytosis, liver damage and pro-inflammatory cytokine production. Conversely, ST2-/- mice (deficient in IL-33 receptor) infected with DENV2 developed significantly less severe disease compared to wild-type (WT) mice. Furthermore, the increased disease severity and the accompanying pathology induced by IL-33 during dengue infection were reversed by the simultaneous treatment with a CXCR2 receptor antagonist (DF2156A). Together, these results indicate that IL-33 plays a disease-exacerbating role in experimental dengue infection, likely driven by CXCR2-expressing cells, leading to elevated pro-inflammatory response-mediated pathology. Our results also indicate that IL-33 is a potential therapeutic target for dengue infection.

National audience

National audience

National audience; Beta-defensins are highly conserved cationic peptides known in mammals to directly modulate host’s immune responses and to control pathogen spread, notably bacteria [1]. In birds, avian beta-defensins (AvBDs) constitute the largest family of innate immunity antimicrobial peptides [2], although their functions are less documented as compared to human beta-defensins. AvBD2 and AvBD7, two major beta-defensins found in chicken heterophils and intestinal epithelial cells, display broad-spectrum antibacterial activity and resistance to proteolysis [3,4]. However, their capacity to modulate inflammation induced by avian pathogenic Escherichia coli (APEC) during colibacillosis, the most important bacterial disease of poultry, is not known. Moreover, the role of these defensins in the control of viral diseases including avian influenza viruses (AIV) in chickens still remains to be elucidated.In the present study, we investigated whether AvBDs could modulate the response of avian macrophages (HD11 cell line) to APEC LPS (O2 and O78) in vitro. None of the two defensins was able to directly or indirectly inhibit LPS-induced nitric oxide release by macrophages. However, AvBD2 (5 μM), but not AvBD7, was able to stimulate macrophages to produce nitric oxide.In addition, the capacity of the two AvBDs to limit the replication of an H1N1 subtype avian influenza virus (AIV) in chicken lung epithelial cells (CLEC213 cell line) was investigated. Interestingly, AvBD2 (0.5 μM), but not AvBD7, was shown to significantly reduce the cytotoxicity of AIV infection in epithelial cells by measuring ATP as a surrogate for cell viability.Taken together these results reveal for the first time substantial differences in the biological activity pattern between AvBD2 and AvBD7, with AvBD2 exerting pro-inflammatory effects on avian macrophages and antiviral effects against avian influenza viruses in chicken lung epithelial cells.

The microarray data presented in this article have been submitted to the Gene Expression Omnibus database (http://www.ncbi.nlm.nih.gov/geo/) under accession number GSE80008. The online version of this article contains supplemental material.; International audience; IFN-stimulated gene 15 (ISG15) deficiency in humans leads to severe IFNopathies and mycobacterial disease, the latter being previously attributed to its extracellular cytokine-like activity. In this study, we demonstrate a novel role for secreted ISG15 as an IL-10 inducer, unique to primary human monocytes. A balanced ISG15-induced monocyte/IL-10 versus lymphoid/IFN-γ expression, correlating with p38 MAPK and PI3K signaling, was found using targeted in vitro and ex vivo systems analysis of human transcriptomic datasets. The specificity and MAPK/PI3K-dependence of ISG15-induced monocyte IL-10 production was confirmed in vitro using CRISPR/Cas9 knockout and pharmacological inhibitors. Moreover, this ISG15/IL-10 axis was amplified in leprosy but disrupted in human active tuberculosis (TB) patients. Importantly, ISG15 strongly correlated with inflammation and disease severity during active TB, suggesting its potential use as a biomarker, awaiting clinical validation. In conclusion, this study identifies a novel anti-inflammatory ISG15/IL-10 myeloid axis that is disrupted in active TB.

Open Access; International audience; Lipid mediators are known to play important roles in the onset and resolution phases of the inflammatory response in mammals. The phospholipid platelet-activating factor (PAF) is a pro-inflammatory lipid mediator which participates in vascular- and innate immunity-associated processes by increasing vascular permeability, by facilitating leukocyte adhesion to the endothelium, and by contributing to phagocyte activation. PAF exerts its function upon binding to its specific receptor, PAF receptor (PAFR), which is abundantly expressed in leukocytes and endothelial cells (ECs). In chickens, lipid mediators and their functions are still poorly characterized, and the role of PAF as an inflammatory mediator has not yet been investigated. In the present study we demonstrate that primary chicken macrophages express PAFR and lysophosphatidylcholine acyltransferase 2 (LPCAT2), the latter being essential to PAF biosynthesis during inflammation. Also, exogenous PAF treatment induces intracellular calcium increase, reactive oxygen species release, and increased phagocytosis by primary chicken macrophages in a PAFR-dependent manner. We also show that PAF contributes to the Escherichia coli lipopolysaccharide (LPS)-induced pro-inflammatory response and boosts the macrophage response to E. coli LPS via phosphatidylinositol 3-kinase/Akt- and calmodulin kinase II-mediated intracellular signaling pathways. Exogenous PAF treatment also increases avian pathogenic E. coli intracellular killing by chicken macrophages, and PAFR and LPCAT2 are upregulated in chicken lungs and liver during experimental pulmonary colibacillosis. Finally, exogenous PAF treatment increases cell permeability and upregulates the expression of genes coding for proteins involved in leukocyte adhesion to the endothelium in primary chicken endothelial cells (chAEC). In addition to these vascular phenomena, PAF boosts the chAEC inflammatory response to bacteria-associated molecular patterns in a PAFR-dependent manner. In conclusion, we identified PAF as an inflammation amplifier in chicken macrophages and ECs, which suggests that PAF could play important roles in the endothelium-innate immunity interface in birds during major bacterial infectious diseases such as colibacillosis.

We report here the complete genome sequences of two Myoviridae phages that infect various avian-pathogenic Escherichia coli strains and that are closely related to phage phAPEC8.

We report here the complete genome sequences of two Myoviridae phages that infect various avian-pathogenic Escherichia coli strains and that are closely related to phage phAPEC8.

International audience; Vasoactive peptides are key early mediators of inflammation released through activation of different enzymatic systems. The mammalian kinin-kallikrein (K-KLK) system produces bradykinin (BK) through proteolytic cleavage of a kininogen precursor by enzymes named kallikreins. BK acts through specific ubiquitous G-protein coupled receptors (B1R and B2R) to participate in physiological processes and inflammatory responses, such as activation of mononuclear phagocytes. In chickens, the BK-like nonapeptide omithokinin (OK) has been shown to promote intracellular calcium increase in embryonic fibroblasts and to be vasodilatory in vivo. Also, one of its receptors (B2R) was already cloned. However, the participation of chicken K-KLK system components in the inflammatory response remains unknown and was therefore investigated. We first showed that B1R, B2R and kininogen 1 (KNG1) are expressed in unstimulated chicken tissues and macrophages. We next showed that chicken B1R and B2R are expressed at transcript and protein levels in chicken macrophages and are upregulated by E. coli LPS or avian pathogenic E. coli (APEC) infection. Interestingly, exogenous OK induced internalization and degradation of OK receptors protein, notably B2R. Also, OK induced intracellular calcium increase and potentiated zymosan-induced ROS production and Dextran-FITC endocytosis by chicken macrophages. Exogenous OK itself did not promote APEC killing and had no pro-inflammatory effect. However, when combined with LPS or APEC, OK upregulated cytokine/chemokine gene expression and NO production by chicken macrophages. This effect was not blocked by canonical non-peptide B1R or B2R receptor antagonists but was GPCR- and PI3K/Akt-dependent. In vivo, pulmonary colibacillosis led to upregulation of OK receptors expression in chicken lungs and liver. Also, colibacillosis led to significant upregulation of OK precursor KNG1 expression in liver and in cultured hepatocytes (LMH). We therefore provide hitherto unknown information on how OK and its receptors are involved in inflammation and infection in chickens.

Marques, Rafael Elias Guabiraba, Rodrigo Russo, Remo Castro Teixeira, Mauro Martins Wellcome Trust/United Kingdom England Expert Opin Ther Targets. 2013 Dec;17(12):1439-60. doi: 10.1517/14728222.2013.837886. Epub 2013 Oct 3.; International audience; INTRODUCTION: Chemokines play important roles in inflammation and in immune responses. This article will discuss the current literature on the C-C chemokine ligand 5 (CCL5), and whether it is a therapeutic target in the context of various allergic, autoimmune or infectious diseases. AREAS COVERED: Small-molecule inhibitors, chemokine and chemokine receptor-deficient mice, antibodies and modified chemokines are the current tools available for CCL5 research, and there are several ongoing clinical trials targeting the CCL5 receptors, CCR1, CCR3 and CCR5. There are fewer studies specifically targeting the chemokine itself and clinical studies with anti-CCL5 antibodies are still to be carried out. EXPERT OPINION: Although clinical trials are strongly biased toward HIV treatment and prevention with blockers of CCR5, the therapeutic potential for CCL5 and its receptors in other diseases is relevant. Overall, it is not likely that specific targeting of CCL5 will result in new adjunct strategies for the treatment of infectious diseases with a major inflammatory component. However, targeting CCL5 could result in novel therapies for chronic inflammatory diseases, where it may decrease inflammatory responses and fibrosis, and certain solid tumors, where it may have a role in angiogenesis.

Dengue virus (DENV), a mosquito-borne flavivirus, is a public health problem in many tropical countries. IL-22 and IL-17A are key cytokines in several infectious and inflammatory diseases. We have assessed the contribution of IL-22 and IL-17A in the pathogenesis of experimental dengue infection using a mouse-adapted DENV serotype 2 strain (P23085) that causes a disease that resembles severe dengue in humans. We show that IL-22 and IL-17A are produced upon DENV-2 infection in immune-competent mice. Infected IL-22(-/-) mice had increased lethality, neutrophil accumulation and pro-inflammatory cytokines in tissues, notably IL-17A. Viral load was increased in spleen and liver of infected IL-22(-/-) mice. There was also more severe liver injury, as seen by increased transaminases levels and tissue histopathology. γδ T cells and NK cells are sources of IL-17A and IL-22, respectively, in liver and spleen. We also show that DENV-infected HepG2 cells treated with rhIL-22 had reduced cell death and decreased IL-6 production. IL-17RA(-/-) mice were protected upon infection and IL-17A-neutralizing-Ab-treatment partially reversed the phenotype observed in IL-22(-/-) -infected mice. We suggest that disrupting the balance between IL-22 and IL-17A levels may represent an important strategy to reduce inflammation and tissue injury associated with severe dengue infection.

International audience

Background Locomotor disorders and infections by Escherichia coli represent major concerns to the poultry industry worldwide. Avian pathogenic E. coli (APEC) is associated with extraintestinal infections leading to respiratory or systemic disease known as colibacillosis. The most common lesions seen in cases of colibacillosis are perihepatitis, airsacculitis, pericarditis, peritonitis/salpingitis and arthritis. These diseases are responsible for significant economic losses in the poultry industry worldwide. E. coli has been recently isolated from vertebral osteomyelitis cases in Brazil and there are no data on molecular and phenotypic characteristics of E. coli strains isolated from lesions in the locomotor system of broilers. This raised the question whether specific E. coli strains could be responsible for bone lesions in broilers. The aim of this study was to assess these characteristics of E. coli strains isolated from broilers presenting vertebral osteomyelitis and arthritis in Brazil. Results Fifteen E. coli strains from bone lesions were submitted to APEC diagnosis and setting of ECOR phylogenic group, O serogroup, flagella type, virulence genes content, genetic patterns by Pulsed Field Gel Electrophoresis (PFGE) and Multilocus Sequence Typing (MLST). In addition, bacterial isolates were further characterized through a lethality test, serum resistance test and antibiotic resistance profile. E. coli strains harbored different genetic pattern as assessed by PFGE, regardless of flock origin and lesion site. The strains belonged to seven sequence types (STs) previously described (ST117, ST101, ST131, ST 371 and ST3107) or newly described in this study (ST5766 and ST5856). ECOR group D (66.7 %) was the most frequently detected. The strains belonged to diverse serogroups (O88, O25, O12, and O45), some of worldwide importance. The antibiotic resistance profile confirmed strains’ diversity and revealed a high proportion of multidrug-resistant strains (73 %), mainly to quinolones and beta-lactams, including third generation cephalosporin. The percentage of resistance to tetracycline was moderate (33 %) but always associated with multidrug resistance. Conclusions Our results demonstrated that vertebral osteomyelitis and arthritis in broilers can be associated with highly diverse E. coli based on molecular and phenotypic characteristics. There was no specific virulence patterns of the E. coli strains associated with vertebral osteomyelitis or arthritis. Also, E. coli strains were frequently multidrug resistant and belonged to STs commonly shared by APEC and human ExPEC strains. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0762-0) contains supplementary material, which is available to authorized users.

Immunology developed under the notion of the immune system exists to fight pathogens. Recently, the discovery of interactions with commensal microbiota that are essential to human health initiated a change in this old paradigm. Here, we argue that the immune system has major physiological roles extending far beyond defending the host. Immune and inflammatory responses share the core property of sensing, defining the immune system also as a sensory system. The inference with the immune system collects, interprets, and stores information, while creating an identity of self, places it in close relationship to the nervous system, which suggests that these systems may have a profound evolutionary connection. ispartof: FRONTIERS IN IMMUNOLOGY vol:7 issue:MAR ispartof: location:Switzerland status: published

Soares, Alexandre Learth Coelho, Fernando Rodrigues Guabiraba, Rodrigo Kamal, Mamdouh Vargaftig, B Boris Li, Lily Li, Jian Tavares-de-Lima, Wothan Ryffel, Bernhard Augusta, Ga. Shock. 2010 Sep;34(3):306-13. doi: 10.1097/SHK.0b013e3181cdc585.; International audience; Intestinal ischemia-reperfusion (I/R) injury may cause acute systemic and lung inflammation. Here, we revisited the role of TNF-alpha in an intestinal I/R model in mice, showing that this cytokine is not required for the local and remote inflammatory response upon intestinal I/R injury using neutralizing TNF-alpha antibodies and TNF ligand-deficient mice. We demonstrate increased neutrophil recruitment in the lung as assessed by myeloperoxidase activity and augmented IL-6, granulocyte colony-stimulating factor, and KC levels, whereas TNF-alpha levels in serum were not increased and only minimally elevated in intestine and lung upon intestinal I/R injury. Importantly, TNF-alpha antibody neutralization neither diminished neutrophil recruitment nor any of the cytokines and chemokines evaluated. In addition, the inflammatory response was not abrogated in TNF and TNF receptors 1 and 2-deficient mice. However, in view of the damage on the intestinal barrier upon intestinal I/R with systemic bacterial translocation, we asked whether Toll-like receptor (TLR) activation is driving the inflammatory response. In fact, the inflammatory lung response is dramatically reduced in TLR2/4-deficient mice, confirming an important role of TLR receptor signaling causing the inflammatory lung response. In conclusion, endogenous TNF-alpha is not or minimally elevated and plays no role as a mediator for the inflammatory response upon ischemic tissue injury. By contrast, TLR2/4 signaling induces an orchestrated cytokine/chemokine response leading to local and remote pulmonary inflammation, and therefore disruption of TLR signaling may represent an alternative therapeutic target.

Guabiraba, Rodrigo Campanha-Rodrigues, Ana Lucia Souza, Adriano L S Santiago, Helton C Lugnier, Claire Alvarez-Leite, Jacqueline Lemos, Virginia S Teixeira, Mauro M Netherlands Eur J Pharmacol. 2010 May 10;633(1-3):85-92. doi: 10.1016/j.ejphar.2010.01.021. Epub 2010 Feb 10.; International audience; Reactive oxygen species, cytokines and chemokines produced at inflammatory sites are pivotal events in the progression of many diseases. Flavonoids are well-known for their antioxidant and anti-inflammatory activities. Here, we investigated the effects of the flavonoid dioclein on the production of mediators of inflammation in vitro and possible underlying mechanisms. Murine macrophages were pretreated with dioclein, rolipram, a PDE4 (cyclic nucleotide phosphosdiesterase type 4) inhibitor, or butylated hydroxytoluene (BHT), an antioxidant, and then activated with LPS or LPS/IFN-gamma. The concentration of TNF-alpha, IL-6, CXCL1/KC, CCL2/JE, and nitric oxide (NO) was determined on culture supernatants. To evaluate potential mechanisms of action, dioclein was tested for inhibition of PDE4 activity and for antioxidant properties by chemiluminescence assays. Dioclein was efficient in reducing the production of cytokines, chemokines and NO in a concentration-dependent manner (from 5 to 50muM). Dioclein was more effective than BHT and rolipram, while having similar inhibitory effects to the combination of BHT plus rolipram. Dioclein inhibited PDE4 activity with an approximate IC(50) of 16.8+/-1.4muM and strongly reduced the concentration of reactive oxygen species in cell and cell-free systems, being more effective than the standard antioxidant BHT. The flavonoid dioclein possesses significant antioxidant and PDE4 inhibitory activity, showing that the substance may have substantial advantages over mechanisms of action already described for many flavonoids. Such effects account for the anti-inflammatory effects of dioclein, mainly by reducing the concentration of mediators of inflammation, such as cytokines, chemokines and reactive oxygen species by macrophages.

Russo, Remo C Guabiraba, Rodrigo Garcia, Cristiana C Barcelos, Luciola S Roffe, Ester Souza, Adriano L S Amaral, Flavio A Cisalpino, Daniel Cassali, Geovanni D Doni, Andrea Bertini, Riccardo Teixeira, Mauro M Am J Respir Cell Mol Biol. 2009 Apr;40(4):410-21. doi: 10.1165/rcmb.2007-0364OC. Epub 2008 Oct 3.; International audience; Pulmonary fibrosis is characterized by chronic inflammation and excessive collagen deposition. Neutrophils are thought to be involved in the pathogenesis of lung fibrosis. We hypothesized that CXCR2-mediated neutrophil recruitment is essential for the cascade of events leading to bleomycin-induced pulmonary fibrosis. CXCL1/KC was detected as early as 6 hours after bleomycin instillation and returned to basal levels after Day 8. Neutrophils were detected in bronchoalveolar lavage and interstitium from 12 hours and peaked at Day 8 after instillation. Treatment with the CXCR2 receptor antagonist, DF2162, reduced airway neutrophil transmigration but led to an increase of neutrophils in lung parenchyma. There was a significant reduction in IL-13, IL-10, CCL5/RANTES, and active transforming growth factor (TGF)-beta(1) levels, but not on IFN-gamma and total TGF-beta(1,) and enhanced granulocyte macrophage-colony-stimulating factor production in DF2162-treated animals. Notably, treatment with the CXCR2 antagonist led to an improvement of the lung pathology and reduced collagen deposition. Using a therapeutic schedule, DF2162 administered from Days 8 to 16 after bleomycin reduced pulmonary fibrosis and levels of active TGF-beta(1) and IL-13. DF2162 treatment reduced bleomycin-induced expression of von Willebrand Factor, a marker of angiogenesis, in the lung. In vitro, DF2162 reduced the angiogenic activity of IL-8 on human umbilical vein endothelial cells. In conclusion, we show that CXCR2 plays an important role in mediating fibrosis after bleomycin instillation. The compound blocks angiogenesis and the production of pro-angiogenic cytokines, and decreases IL-8-induced endothelial cell activation. An effect on neutrophils does not appear to account for the major effects of the blockade of CXCR2 in the system.

Drug-induced liver injury (DILI) is an important cause of acute liver failure, with limited therapeutic options. During DILI, oncotic necrosis with concomitant release and recognition of intracellular content amplifies liver inflammation and injury. Among these molecules, self-DNA has been widely shown to trigger inflammatory and autoimmune diseases; however, whether DNA released from damaged hepatocytes accumulates into necrotic liver and the impact of its recognition by the immune system remains elusive. Here we show that treatment with two different hepatotoxic compounds (acetaminophen and thioacetamide) caused DNA release into the hepatocyte cytoplasm, which occurred in parallel with cell death in vitro. Administration of these compounds in vivo caused massive DNA deposition within liver necrotic areas, together with an intravascular DNA coating. Using confocal intravital microscopy, we revealed that liver injury due to acetaminophen overdose led to a directional migration of neutrophils to DNA-rich areas, where they exhibit an active patrolling behavior. DNA removal by intravenous DNASE1 injection or ablation of Toll-like receptor 9 (TLR9)-mediated sensing significantly reduced systemic inflammation, liver neutrophil recruitment, and hepatotoxicity. Analysis of liver leukocytes by flow cytometry revealed that emigrated neutrophils up-regulated TLR9 expression during acetaminophen-mediated necrosis, and these cells sensed and reacted to extracellular DNA by activating the TLR9/NF-κB pathway. Likewise, adoptive transfer of wild-type neutrophils to TLR9−/− mice reversed the hepatoprotective phenotype otherwise observed in TLR9 absence. Conclusion: Hepatic DNA accumulation is a novel feature of DILI pathogenesis. Blockage of DNA recognition by the innate immune system may constitute a promising therapeutic venue. (Hepatology 2015;61:348–360)

Avian pathogenic Escherichia coli (APEC) strains cause severe respiratory and systemic diseases, threatening food security and avian welfare worldwide. Intensification of poultry production and the quick expansion of free-range production systems will increase the incidence of colibacillosis through greater exposure of birds to pathogens and stress. Therapy is mainly based on antibiotherapy and current vaccines have poor efficacy. Serotyping remains the most frequently used diagnostic method, only allowing the identification of a limited number of APEC strains. Several studies have demonstrated that the most common virulence factors studied in APEC are all rarely present in the same isolate, showing that APEC strains constitute a heterogeneous group. Different isolates may harbor different associations of virulence factors, each one able to induce colibacillosis. Despite its economical relevance, pathogenesis of colibacillosis is poorly understood. Our knowledge on the host response to APEC is based on very descriptive studies, mostly restricted to bacteriological and histopathological analysis of infected organs such as lungs. Furthermore, only a small number of APEC isolates have been used in experimental studies. In the present review, we discuss current knowledge on APEC diversity and virulence, including host response to infection and the associated inflammatory response with a focus on pulmonary colibacillosis.

Dengue is a mosquito-borne disease that affects millions of people worldwide yearly. Currently, there is no vaccine or specific treatment available. Further investigation on dengue pathogenesis is required to better understand the disease and to identify potential therapeutic targets. The chemokine system has been implicated in dengue pathogenesis, although the specific role of chemokines and their receptors remains elusive. Here we describe the role of the CC-chemokine receptor CCR5 in Dengue virus (DENV-2) infection. In vitro experiments showed that CCR5 is a host factor required for DENV-2 replication in human and mouse macrophages. DENV-2 infection induces the expression of CCR5 ligands. Incubation with an antagonist prevents CCR5 activation and reduces DENV-2 positive-stranded (+) RNA inside macrophages. Using an immunocompetent mouse model of DENV-2 infection we found that CCR5(-/-) mice were resistant to lethal infection, presenting at least 100-fold reduction of viral load in target organs and significant reduction in disease severity. This phenotype was reproduced in wild-type mice treated with CCR5-blocking compounds. Therefore, CCR5 is a host factor required for DENV-2 replication and disease development. Targeting CCR5 might represent a therapeutic strategy for dengue fever. These data bring new insights on the association between viral infections and the chemokine receptor CCR5.

Souza, Adriano L S Roffe, Ester Pinho, Vanessa Souza, Danielle G Silva, Adriana F Russo, Remo C Guabiraba, Rodrigo Pereira, Cintia A J Carvalho, Flavia M Barsante, Michele M Correa-Oliveira, Rodrigo Fraga, Lucia A O Negrao-Correa, Deborah Teixeira, Mauro M Infect Immun. 2005 Apr;73(4):2515-23.; International audience; In human schistosomiasis, the concentrations of the chemokine macrophage inflammatory protein 1α (MIP-1alpha/CCL3) is greater in the plasma of patients with clinical hepatosplenic disease. The objective of the present study was to confirm the ability of CCL3 to detect severe disease in patients classified by ultrasonography (US) and to evaluate the potential role of CCL3 in Schistosoma mansoni-infected mice. CCL3 was measured by enzyme-linked immunosorbent assay in the plasma of S. mansoni-infected patients. CCL3-deficient mice were infected with 25 cercariae, and various inflammatory and infectious indices were evaluated. The concentration of CCL3 was higher in the plasma of S. mansoni-infected than noninfected patients. Moreover, CCL3 was greater in those with US-defined hepatosplenic than with the intestinal form of the disease. In CCL3-deficient mice, the size of the granuloma and the liver eosinophil peroxidase activity and collagen content were diminished compared to wild-type mice. In CCL3-deficient mice, the worm burden after 14 weeks of infection, but not after 9 weeks, was consistently smaller. The in vitro response of mesenteric lymph node cells to antigen stimulation was characterized by lower levels of interleukin-4 (IL-4) and IL-10. CCL3 is a marker of disease severity in infected humans, and experimental studies in mice suggest that CCL3 may be a causative factor in the development of severe schistosomiasis.

International audience; Th9 cells protect hosts against helminthic infection but also mediate allergic disease. Here we show that nitric oxide (NO) promotes Th9 cell polarization of murine and human CD4(+) T cells. NO de-represses the tumour suppressor gene p53 via nitrosylation of Mdm2. NO also increases p53-mediated IL-2 production, STAT5 phosphorylation and IRF4 expression, all essential for Th9 polarization. NO also increases the expression of TGFβR and IL-4R, pivotal to Th9 polarization. OVA-sensitized mice treated with an NO donor developed more severe airway inflammation. Transferred Th9 cells induced airway inflammation, which was exacerbated by NO and blocked by anti-IL-9 antibody. Nos2(-/-) mice had less Th9 cells and developed attenuated eosinophilia during OVA-induced airway inflammation compared with wild-type mice. Our data demonstrate that NO is an important endogenous inducer of Th9 cells and provide a hitherto unrecognized mechanism for NO-mediated airway inflammation via the expansion of Th9 cells.

Guabiraba, Rodrigo Ryffel, Bernhard Immunology. 2013 Oct 12. doi: 10.1111/imm.12188.; International audience; Dengue viruses (DENV), a group of four serologically distinct but related flaviviruses, are responsible for one of the most important emerging viral diseases. This mosquito-borne disease has a great impact in tropical and subtropical areas of the world in terms of illness, mortality, and economic costs, mainly due to the lack of approved vaccine or antiviral drugs. Infections with one of the four serotypes of DENV (DENV-1-4) result in symptoms ranging from an acute, self-limiting febrile illness (dengue fever, DF) to severe dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). We reviewed the existing mouse models of infection, including the DENV-2 adapted strain P23085. The role of CC chemokines, IL-17, IL-22 and invariant NKT (iNKT) cells in mediating the exacerbation of disease in immune competent mice is highlighted. Investigations in both immune deficient and competent mouse models of DENV infection may help identify key host-pathogen factors and devise novel therapies to restrain the systemic and local inflammatory responses associated to severe dengue infection. This article is protected by copyright. All rights reserved.