The Intestinal Microbiota Contributes to the Ability of Helminths to Modulate Allergic Inflammation

We thank Manuel Kulagin for technical help, Pierre Bonnaventure for portal vein blood sampling, Francisco Sepulveda for technical assistance in GS-MS acquisition, and Dorothee Hahne (Metabolomics Australia, University of Western Australia) for human samples SCFA isolation, acquisition, and analysis. We also thank Cristina Cartoni (Phenotyping Unit, EPFL) for Milliplex analysis, Jessica Dessimoz and her team from the Histology Core Facility (EPFL), Miguel Garcia and his team from the Flow Cytometry Core Facility (EPFL), and staff from the EPFL CPG animal house for excellent animal care. The computations were partially performed at the Vital-IT Center for high-performance computing of the SIB Swiss Institute of Bioinformatics (http://www.vital-it.ch). The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 310948. Funding for A.W.W. and a subset of the 16S rRNA gene sequencing was provided by the Wellcome Trust (grant number WT 098051). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Mechanisms of Intestinal Epithelial Barrier Dysfunction by Adherent-Invasive Escherichia coli.

Pathobiont expansion, such as that of adherent-invasive Escherichia coli (AIEC), is an emerging factor associated with inflammatory bowel disease. The intestinal epithelial barrier is the first line of defense against these pathogens. Inflammation plays a critical role in altering the epithelial barrier and is a major factor involved in promoting the expansion and pathogenesis of AIEC. AIEC in turn can exacerbate intestinal epithelial barrier dysfunction by targeting multiple elements of the barrier. One critical element of the epithelial barrier is the tight junction. Increasing evidence suggests that AIEC may selectively target protein components of tight junctions, leading to increased barrier permeability. This may represent one mechanism by which AIEC could contribute to the development of inflammatory bowel disease. This review article discusses potential mechanisms by which AIEC can disrupt epithelial tight junction function and intestinal barrier function

Caspase-8 controls the gut response to microbial challenges by Tnf-alpha-dependent and independent pathways

Objectives: Intestinal epithelial cells (IEC) express toll-like receptors (TLR) that facilitate microbial recognition. Stimulation of TLR ligands induces a transient increase in epithelial cell shedding, a mechanism that serves the antibacterial and antiviral host defence of the epithelium and promotes elimination of intracellular pathogens. Although activation of the extrinsic apoptosis pathway has been described during inflammatory shedding, its functional involvement is currently unclear. Design: We investigated the functional involvement of caspase-8 signalling in microbial-induced intestinal cell shedding by injecting Lipopolysaccharide (LPS) to mimic bacterial pathogens and poly(I:C) as a probe for RNA viruses in vivo. Results: TLR stimulation of IEC was associated with a rapid activation of caspase-8 and increased epithelial cell shedding. In mice with an epithelial cell-specific deletion of caspase-8 TLR stimulation caused Rip3-dependent epithelial necroptosis instead of apoptosis. Mortality and tissue damage were more severe in mice in which IECs died by necroptosis than apoptosis. Inhibition of receptor-interacting protein (Rip) kinases rescued the epithelium from TLR-induced gut damage. TLR3-induced necroptosis was directly mediated via TRIF-dependent pathways, independent of Tnf-α and type III interferons, whereas TLR4-induced tissue damage was critically dependent on Tnf-α. Conclusions: Together, our data demonstrate an essential role for caspase-8 in maintaining the gut barrier in response to mucosal pathogens by permitting inflammatory shedding and preventing necroptosis of infected cells. These data suggest that therapeutic strategies targeting the cell death machinery represent a promising new option for the treatment of inflammatory and infective enteropathies

α-Lactosylceramide Protects Against iNKT-Mediated Murine Airway Hyperreactivity and Liver Injury Through Competitive Inhibition of Cd1d Binding.

Invariant natural killer T (iNKT) cells, which are activated by T cell receptor (TCR)-dependent recognition of lipid-based antigens presented by the CD1d molecule, have been shown to participate in the pathogenesis of many diseases, including asthma and liver injury. Previous studies have shown the inhibition of iNKT cell activation using lipid antagonists can attenuate iNKT cell-induced disease pathogenesis. Hence, the development of iNKT cell-targeted glycolipids can facilitate the discovery of new therapeutics. In this study, we synthesized and evaluated α-lactosylceramide (α-LacCer), an α-galactosylceramide (α-GalCer) analog with lactose substitution for the galactose head and a shortened acyl chain in the ceramide tail, toward iNKT cell activation. We demonstrated that α-LacCer was a weak inducer for both mouse and human iNKT cell activation and cytokine production, and the iNKT induction by α-LacCer was CD1d-dependent. However, when co-administered with α-GalCer, α-LacCer inhibited α-GalCer-induced IL-4 and IFN-γ production from iNKT cells. Consequently, α-LacCer also ameliorated both α-GalCer and GSL-1-induced airway hyperreactivity and α-GalCer-induced neutrophilia when co-administered in vivo. Furthermore, we were able to inhibit the increases of ConA-induced AST, ALT and IFN-γ serum levels through α-LacCer pre-treatment, suggesting α-LacCer could protect against ConA-induced liver injury. Mechanistically, we discerned that α-LacCer suppressed α-GalCer-stimulated cytokine production through competing for CD1d binding. Since iNKT cells play a critical role in the development of AHR and liver injury, the inhibition of iNKT cell activation by α-LacCer present a possible new approach in treating iNKT cell-mediated diseases

CCR1 as a therapeutic target in multiple myeloma: preventing tumour dissemination and therapeutic resistance

Multiple myeloma (MM) is a haematological malignancy characterised by the clonal proliferation of plasma cells (PC) within the bone marrow (BM). While the introduction of novel therapies, such as the proteasome inhibitor bortezomib, has greatly improved patient outcomes, a subset of patients still does very poorly, due to intrinsic resistance to therapy, rapid disease relapse and increased tumour dissemination. However, the mechanisms which underpin MM PC dissemination and intrinsic resistance remain poorly understood. Our laboratory has previously shown that MM PC expression of the chemokine receptor CCR1 is associated with poor prognosis in newly diagnosed patients. In this thesis, the mechanisms underlying the prognostic disadvantage of elevated CCR1 expression are explored. In addition, the prognostic significance of MM PC expression of other chemokine receptors is also investigated. MM disease development, progression and relapse is dependent on MM PC haematogenous dissemination from one bone site to another. Currently, there is little understanding of which factors regulate spontaneous dissemination. Our previous studies suggested that elevated MM PC CCR1 expression is associated with increased numbers of circulating MM PC in newly diagnosed patients. Here, is was found that knockout of CCR1 in the MM cell line OPM2 resulted in almost no circulating tumour cells and prevented the formation of disseminated tumours following intratibial injection, suggesting that CCR1 is critical in egress from the BM to the circulation. In support of this, constitutive expression of CCR1 in 5TGM1 MM cells increased the incidence of disseminated tumours in C57BL/KaLwRij mice. Furthermore, pharmacological inhibition of CCR1 slowed the formation of disseminated tumours in intratibial RPMI-8226 or OPM2 tumour models. These studies support the further investigation of CCR1 inhibition as a therapeutic modality to inhibit MM tumour dissemination. The poor prognosis associated with CCR1 expression in MM patients suggests that CCR1 may also play a role in therapeutic resistance. In order to investigate this, the effect of CCR1 overexpression and knockdown in MM cell lines on response to bortezomib treatment was assessed. CCR1 knockout increased bortezomib sensitivity in vitro and in vivo, while constitutive expression of CCR1 decreased bortezomib sensitivity in vitro. Furthermore, RNA sequencing analysis revealed that elevated MM PC CCR1 expression at diagnosis or at relapse was associated with poorer overall survival in patients receiving bortezomib treatment. Future studies are warranted to assess the ability of CCR1 inhibitors to increase response to bortezomib. In order to investigate the potential role of other chemokine receptors in MM pathogenesis, we conducted an in silico analysis to determine the association between chemokine receptor expression on MM PCs and overall survival in MM patients. These studies identified, for the first time, that elevated CCR10 expression is associated with poor prognosis. Notably, elevated MM PC CCR10 mRNA or protein expression was not associated with other known prognostic factors in MM patients. Taken together, these studies suggest that CCR1 is a potential target to enhance response to therapy and prevent dissemination of MM PCs. In addition, they suggest that future studies are warranted to investigate the role of CCR10 in MM pathogenesisThesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 202

Interplanetary scintillation and pulsar pulse statistics

The effect of interplanetary plasma on pulsed pulsar radiation passing through is considered. The pulses of two rotating radio transients (J0609+16, J1132+25) and a pulsar (B0320+39) detected on the Large Phased Array (Pushchino observatory) were analyzed. It is shown that in observations at the frequency of 111 MHz, on elongations of 20o-40o, both an increase and a decrease in the number of received pulses are observed. The change in the number of pulses is explained by the distortion of the energy distribution of pulses due to interplanetary scintillation. These changes in the number of observed pulses are in qualitative agreement with the expected dependence of the scintillation index on the observed sources elongation. Analytical expressions are obtained that allow estimating the effective modulation index from observations of individual pulses for the power distribution of pulses by energy.Comment: accepted to MNRAS, 5 pages, 3 figure

Genetics of inflammatory bowel disease from multifactorial to monogenic forms

Inflammatory bowel disease (IBD) is a group of chronic multifactorial disorders. According to a recent study, the number of IBD association loci is increased to 201, of which 37 and 27 loci contribute specifically to the development of Crohn\u2019s disease and ulcerative colitis respectively. Some IBD associated genes are involved in innate immunity, in the autophagy and in the inflammatory response such as NOD2, ATG16L1 and IL23R, while other are implicated in immune mediated disease (STAT3) and in susceptibility to mycobacterium infection (IL12B). In case of early onset of IBD (VEO-IBD) within the 6th year of age, the disease may be caused by mutations in genes responsible for severe monogenic disorders such as the primary immunodeficiency diseases. In this review we discuss how these monogenic disorders through different immune mechanisms can similarly be responsible of VEO-IBD phenotype. Moreover we would highlight how the identification of pathogenic genes by Next Generation Sequencing technologies can allow to obtain a rapid diagnosis and to apply specific therapies

Mechanisms underlying bone loss associated with gut inflammation

Patients with gastrointestinal diseases frequently suffer from skeletal abnormality, characterized by reduced bone mineral density, increased fracture risk, and/or joint inflammation. This pathological process is characterized by altered immune cell activity and elevated inflammatory cytokines in the bone marrow microenvironment due to disrupted gut immune response. Gastrointestinal disease is recognized as an immune malfunction driven by multiple factors, including cytokines and signaling molecules. However, the mechanism by which intestinal inflammation magnified by gut-residing actors stimulates bone loss remains to be elucidated. In this article, we discuss the main risk factors potentially contributing to intestinal disease-associated bone loss, and summarize current animal models, illustrating gut-bone axis to bridge the gap between intestinal inflammation and skeletal disease