Differences in peripheral and tissue immune cell populations following haematopoietic stem cell transplantation in Crohn's disease patients

Background and aims: recent studies have shown the efficacy of autologous haematopoietic stem cell transplantation [HSCT] in severely refractory Crohn's disease [CD] patients. HSCT is thought to eliminate auto-reactive cells; however, no specific studies of immune reconstitution in CD patients are available. Methods: we followed a group of CD patients [n = 18] receiving autologous HSCT, with 50% of them achieving endoscopic drug-free remission. To elucidate the mechanisms driving efficacy, we monitored changes after HSCT in blood and intestine immune-cell composition. CD patients [n = 22] receiving anti-tumour necrosis factor [TNF]-α were included for comparison. Results: severe immune ablation followed by HSCT induced dramatic changes in both peripheral blood T and B cells in all patients regardless of the efficacy of the treatment. Endoscopic remission at week 52 following HSCT was associated with significant intestinal transcriptional changes. A comparison of the remission signature with that of anti-TNFα identified both common and unique genes in the HSCT-induced response. Based on deconvolution analysis of intestinal biopsy transcriptome data, we show that response to HSCT, but not to anti-TNFα, is associated with an expansion of naïve B-cells, as seen in blood, and a decrease in the memory resting T-cell content. As expected, endoscopic remission, in response to both HSCT and anti-TNFα, led to a significant reduction in intestinal neutrophil and M1 macrophage content. Conclusions: peripheral blood immune remodelling after HSCT does not predict efficacy. In contrast, a profound intestinal T-cell depletion that is maintained long after transplant is associated with mucosal healing following HSCT, but not anti-TNFα

Nod1 and Nod2 in Innate Immune Responses, Adaptive Immunity and Bacterial Infection

The last decade has been witness to a number of seminal discoveries in the field of innate immunity. The discovery that microbial molecules and endogenous danger signals can be detected by germ-line encoded receptors has changed the way we study the immune system. Indeed, the characterization of Toll in Drosophila as a sensor of microbial products in 1997 then led to the discovery of a family of Toll Like Receptors (TLRs) in mammals. TLRs are critical for the induction of inflammatory responses and the generation of a successful adaptive immune response. The array of ligands that these transmembrane proteins recognized mediates defense against bacteria, viruses, fungus and parasites, as well as, possibly, cancerous cells. In addition to this membrane-bound family of recognition proteins, two families of pattern recognition receptors have been recently shown to respond to microbial and chemical ligands within the cytosol. These represent the Nod Like Receptors (NLRs) and RIGI-like helicase receptor (RLH) families. Nod1 and Nod2 are members of the NLR family of proteins, which are responsible for the recognition of components derived from the bacterial cell wall, more precisely, moieties of peptidoglycan. As such, Nod1 and Nod2 are implicated in the recognition and the defense against bacterial pathogens. Importantly, the genes encoding these two proteins have also been linked to the etiology of several inflammatory disorders such as Crohn’s disease and asthma. In this thesis, we show that recognition of Nod1 and Nod2 ligands generates a rapid and transient inflammatory response in vivo. When co-injected with a model protein, Nod1 and Nod2 ligands exhibit adjuvant properties that lead to the generation of an antigen-specific Th2 type adaptive immune response. Surprisingly, recognition of the Nod1 ligand in non-hematopoietic cells is critical for the generation of this immune response. In contrast, TLRs classically tip the balance towards a Th1 response and interestingly, co-injection of TLR and Nod ligands synergize to generate a more potent immune response characterized by the generation of Th1, Th2 and Th17 T cell respones. To study the role of Nod1 and Nod2 in the context of a bacterial infection in vivo, we used an intestinal mouse pathogen, Salmonella enterica serovar Typhimurium. We were able to show that Nod1-deficient mice, but not Nod2-deficient mice, are more susceptible to the strain of this bacterium, which enters the host through the active pickup in the intestinal lumen by underlying myeloid cells. This sampling mechanism is mediated by a subset of dendritic cells that populate the intestinal lamina propria. Accordingly, the defect seen in Nod1-deficient mice localizes to the mucosal barrier where these dendritic cells appear to have an impaired response towards the bacteria. Taken together, these results increase our knowledge on the general role of Nod1 and Nod2 in immunity and might generate new avenues of research and potential therapeutic targets.Ph

Fluorescent hybridisation combined with flow cytometry and hybridisation of total RNA to analyse the composition of microbial communities in human faeces using 16S rRNA probes

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Hybrid piezochromic coatings for impact detection on composite substrates for aeronautic

International audienceStructural Health Monitoring (SHM) is a major issue in the aeronautic field, especially for impact detection on composite materials which can be time consuming. Impact-sensitive coatings are an interesting way to save costs and time associated with these monitoring operations. This paper describes the successful preparation of a reversible piezochromic coating for impacts detection on composite substrates. It results from the incorporation of piezochromic pigments into a hybrid organic-inorganic matrix. It has been optimized by studying and quantifying their piezochromic behavior by UV-visible spectroscopy. It revealed that the piezochromic properties of the sensitive coating and the pigments alone are quite different and ruled by the hardness of the film. The obtained sensitivity and threshold pressure are determined to be 28% GPa−1 and 0.2 GPa respectively

Hybrid piezochromic coatings for impact detection on composite substrates for aeronautic

Structural Health Monitoring (SHM) is a major issue in the aeronautic field, especially for impact detection on composite materials which can be time consuming. Impact-sensitive coatings are an interesting way to save costs and time associated with these monitoring operations. This paper describes the successful preparation of a reversible piezochromic coating for impacts detection on composite substrates. It results from the incorporation of piezochromic pigments into a hybrid organic-inorganic matrix. It has been optimized by studying and quantifying their piezochromic behavior by UV-visible spectroscopy. It revealed that the piezochromic properties of the sensitive coating and the pigments alone are quite different and ruled by the hardness of the film. The obtained sensitivity and threshold pressure are determined to be 28% GPa−1 and 0.2 GPa respectively.Revêtements Piézochromes Réversibles pour la Détection d'Impacts sur Supports Composite

In Vitro and In Vivo Analysis of the Gram-Negative Bacteria-Derived Riboflavin Precursor Derivatives Activating Mouse MAIT Cells.

International audienceMucosal-associated invariant T (MAIT) cells recognize microbial compounds presented by the MHC-related 1 (MR1) protein. Although riboflavin precursor derivatives from Gram-positive bacteria have been characterized, some level of ligand heterogeneity has been suggested through the analysis of the MAIT cell TCR repertoire in humans and differential reactivity of human MAIT cell clones according to the bacteria. In this study, using Gram-negative bacteria mutated for the riboflavin biosynthetic pathway, we show a strict correlation between the ability to synthesize the 5-amino-ribityl-uracil riboflavin precursor and to activate polyclonal and quasi-monoclonal mouse MAIT cells. To our knowledge, we show for the first time that the semipurified bacterial fraction and the synthetic ligand activate murine MAIT cells in vitro and in vivo. We describe new MR1 ligands that do not activate MAIT cells but compete with bacterial and synthetic compounds activating MAIT cells, providing the capacity to modulate MAIT cell activation. Through competition experiments, we show that the most active synthetic MAIT cell ligand displays the same functional avidity for MR1 as does the microbial compound. Altogether, these results show that most, if not all, MAIT cell ligands found in Escherichia coli are related to the riboflavin biosynthetic pathway and display very limited heterogeneity

Effects of post-hatch fast of chick on digestive tract development and growth performance according to diet and rearing environmental conditions

International audienceIn commercial conditions, chicks underwent a post-hatch fast (PHF) between 24 and 72h, and about 24h when hatchery and farm are in the same region. Effects on digestive tract development (DTD) and animal growth are controversial due to several factors such as definition of bird age (from hatching in most studies, or from farm arrival), animal genetics, or dietary and environmental conditions (DEC).Here, the effect of PHF was studied on body weight (BW) and DTD of Ross PM3, during a first experiment (48h fast), with age of birds determined as the age at farm arrival with access to feed and water. To study the effect of DEC, birds were reared either in optimal DEC, or damaged DEC (low quality diet and/or low quality rearing environment) in a 2x2x2 factorial design (6 pens/treatment ; 54 birds/pen of 2.3 m2 of useful area). In a second experiment, the effect of a shorter PHF (24h) was studied on chick BW and DTD.In the first study, PHF showed effects on DTD, BW and animal health, differing according to DEC. At the farm arrival, PHF chicks had lower BW than direct fed (DF) chicks (-3.5 g), due to lower yolk sac (YS) (2.0 vs 5.1 g), but similar BW without YS. The relative weight (rW) of the segments of the DT (expressed relative to BW without YS) was higher in PHF chicks (proventriculus : +37% ; gizzard : +33% ; small intestine (SI) : +27 ; caeca : +79%). At 3 weeks of age (w), PHF showed no effect on the DT, but, at 5 w, a lower rW of gizzard (- 14%) was observed in PHF chickens, irrespective of DEC. No difference in SI morphology was observed at 3 and 5 w, irrespective of DEC, as well as for dry matter ileal digestibility at 3 w. In optimal DEC, PHF led to beneficial effect on BW as well as at 3 w (+5%) and 5 w (+3.5%). Damaged DEC led to a higher decreased BW in PHF than in DF chickens, -12% and -10.5% respectively at 3 w, and -16% and -10% at 5 w. This led to a lower final BW in PHF compared to DF chickens (-3.5%). These damaged DEC led to higher footpad dermatitis in PHF chickens at 3 w, but no difference at 5 w.In the second study, a decrease of chick BW after PHF was also observed (-2.6 g), due to lower YS (3.2 vs 6.0 g), as well as an increase of the rW of the segments of the DT (proventriculus : +21% ; gizzard : +25% ; SI : +23% ; caeca : x 2.75).In conclusion, PHF (24 or 48h) has a positive effect on the chick DTD. These PHF seem beneficial on bird growth in optimal, but not in damaged DEC. This period of live needs to be managed according to DEC

Cocultures of human colorectal tumor spheroids with immune cells reveal the therapeutic potential of MICA/B and NKG2A targeting for cancer treatment

Abstract Background Immunotherapies still fail to benefit colorectal cancer (CRC) patients. Relevant functional assays aimed at studying these failures and the efficacy of cancer immunotherapy in human are scarce. 3D tumor cultures, called tumor organoids or spheroids, represent interesting models to study cancer treatments and could help to challenge these issues. Methods We analyzed heterotypic cocultures of human colon tumor-derived spheroids with immune cells to assess the infiltration, activation and function of T and NK cells toward human colorectal tumors in vitro. Results We showed that allogeneic T and NK cells rapidly infiltrated cell line-derived spheroids, inducing immune-mediated tumor cell apoptosis and spheroid destruction. NKG2D, a key activator of cytotoxic responses, was engaged on infiltrating cells. We thus assessed the therapeutic potential of an antibody targeting the specific ligands of NKG2D, MICA and MICB, in this system. Anti-MICA/B enhanced immune-dependent destruction of tumor spheroid by driving an increased NK cells infiltration and activation. Interestingly, tumor cells reacted to immune infiltration by upregulating HLA-E, ligand of the inhibitory receptor NKG2A expressed by CD8 and NK cells. NKG2A was increased after anti-MICA/B treatment and, accordingly, combination of anti-MICA/B and anti-NKG2A was synergistic. These observations were ultimately confirmed in a clinical relevant model of coculture between CRC patients-derived spheroids and autologous tumor-infiltrating lymphocytes. Conclusions Altogether, we show that tumor spheroids represent a relevant tool to study tumor-lymphocyte interactions on human tissues and revealed the antitumor potential of immunomodulatory antibodies targeting MICA/B and NKG2A