Omp25-dependent engagement of SLAMF1 by Brucella abortus in dendritic cells limits acute inflammation and favours bacterial persistence in vivo

The strategies by which intracellular pathogenic bacteria manipulate innate immunity to establish chronicity are poorly understood. Here, we show that Brucella abortus outer membrane protein Omp25 specifically binds the immune cell receptor SLAMF1 in vitro. The Omp25-dependent engagement of SLAMF1 by B. abortus limits NF-κB translocation in dendritic cells (DCs) with no impact on Brucella intracellular trafficking and replication. This in turn decreases pro-inflammatory cytokine secretion and impairs DC activation. The Omp25-SLAMF1 axis also dampens the immune response without affecting bacterial replication in vivo during the acute phase of Brucella infection in a mouse model. In contrast, at the chronic stage of infection, the Omp25/SLAMF1 engagement is essential for Brucella persistence. Interaction of a specific bacterial protein with an immune cell receptor expressed on the DC surface at the acute stage of infection is thus a powerful mechanism to support microbe settling in its replicative niche and progression to chronicity.Fil: Degos, Clara. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Hysenaj, Lisiena. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Gonzalez Espinoza, Gabriela. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Arce Gorvel, Vilma. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Gagnaire, Aurélie. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Papadopoulos, Alexia. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Pasquevich, Karina Alejandra. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Méresse, Stéphane. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Cassataro, Juliana. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Mémet, Sylvie. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Gorvel, Jean Pierre. Inserm; Francia. Centre National de la Recherche Scientifique; Franci

Les modifications de l'hématopoïèse lors de la brucellose

La brucellose est une maladie qui se transmet de l’animal à l’homme. Elle est causée par la bactérie Brucella. Lors de ma thèse, j’ai montré que Brucella persiste dans les cellules de la moelle osseuse des animaux infectés. Ces observations sont très importantes car la moelle est un organe responsable de la génération des cellules du système immunitaires et c’est la principale niche des cellules souches hématopoïétiques. Au cours de ma thèse, j'ai montré que la protéine de la membrane externe 25 de Brucella (Omp25) est capable de lier au récepteur SLAMF1, une molécule exprimée par les cellules souches hématopoïétiques. Cette interaction conduit à la génération d'un plus grand nombre de cellules myéloïdes par les cellules souches hématopoïétiques. Les cellules myéloïdes sont la niche préférée de Brucella. Ainsi, cette stratégie permet à la bactérie d'envahir l’hôte et d'établir une infection chronique de longue durée. SLAMF 1 apparaît comme une nouvelle cible thérapeutique pour le contrôle des maladies infectieuses chroniques, ce qui représenterait une avancée importante dans la génération de nouveaux médicaments.Brucellosis is a disease that is transmitted from animals to humans. It is caused by the pathogenic bacterium Brucella. During my thesis, I showed that Brucella persists in the bone marrow cells of infected animals. These observations are very important because the bone marrow is an organ of the immune system responsible for the generation of the immune cells, as it is the principal niche of hematopoietic stem cells. During my thesis, I showed that Brucella outer membrane 25 (Omp25) is able to bind SLAMF1, a hematopoietic stem cell molecule. This interaction leads to the production of more myeloid cells by the hematopoietic stem cell. Myeloid cells are the favorite niche of Brucella. Thus, this strategy allows the bacteria to invade the host and establish a long lasting chronic infection. SLAMF 1 appears as a new therapeutic target for controlling chronic infectious diseases, which would represent an important advance in the generation of new drugs

La danse entre Brucella et les cellules souches hématopoïétiques

International audienceNo abstract availabl

CD150-dependent hematopoietic stem cell sensing of Brucella instructs myeloid commitment

International audienceSo far, hematopoietic stem cells (HSC) are considered the source of mature immune cells, the latter being the only ones capable of mounting an immune response. Recent evidence shows HSC can also directly sense cytokines released upon infection/inflammation and pathogen-associated molecular pattern interaction while keeping a long-term memory of previously encountered signals. Direct sensing of danger signals by HSC induces early myeloid commitment, increases myeloid effector cell numbers, and contributes to an efficient immune response. Here, by using specific genetic tools on both the host and pathogen sides, we show that HSC can directly sense B. abortus pathogenic bacteria within the bone marrow via the interaction of the cell surface protein CD150 with the bacterial outer membrane protein Omp25, inducing efficient functional commitment of HSC to the myeloid lineage. This is the first demonstration of direct recognition of a live pathogen by HSC via CD150, which attests to a very early contribution of HSC to immune response

Persistence of Brucella abortus in the bone marrow of infected mice

Brucellosis is a zoonotic bacterial infection that may persist for long periods causing relapses in antibiotic-treated patients. The ability of Brucella to develop chronic infections is linked to their capacity to invade and replicate within the mononuclear phagocyte system, including the bone marrow (BM). Persistence of Brucella in the BM has been associated with hematological complications such as neutropenia, thrombocytopenia, anemia, and pancytopenia in human patients. In the mouse model, we observed that the number of Brucella abortus in the BM remained constant for up to 168 days of postinfection. This persistence was associated with histopathological changes, accompanied by augmented numbers of BM myeloid GMP progenitors, PMNs, and CD4+ lymphocytes during the acute phase (eight days) of the infection in the BM. Monocytes, PMNs, and GMP cells were identified as the cells harboring Brucella in the BM. We propose that the BM is an essential niche for the bacterium to establish long-lasting infections and that infected PMNs may serve as vehicles for dispersion of Brucella organisms, following the Trojan horse hypothesis. Monocytes are solid candidates for Brucella reservoirs in the BM.La brucelosis es una infección bacteriana zoonótica que puede persistir durante largos períodos de tiempo y causar recaídas en pacientes tratados con antibióticos. La posibilidad de que los brucelosos desarrollen infecciones crónicas está vinculada a su capacidad de invadir y replicarse dentro del sistema mononuclear-fagocitario, incluyendo la médula ósea (BM). La persistencia de la Brucellaina la BM ha sido asociada con complicaciones hematológicas como la neutropenia, la trombocitopenia, la anemia y la pancitopenia en pacientes humanos. En el modelo de ratón, observamos que el número de Brucella abortusin la BM se mantuvo constante hasta 168 días después de la infección. Esta persistencia se asoció a cambios histopatológicos, acompañados de un aumento en el número de progenitores mieloides GMP de la BM, PMN y linfocitos CD4+ durante la fase aguda (ocho días) de la infección en la BM. Se identificaron los monocitos, PMNs y células GMP como las células que albergan a la Brucella en la BM. Proponemos que el BM es un nicho esencial para que la bacteria establezca infecciones duraderas y que las PMN infectadas pueden servir como vehículos para la dispersión de los organismos de Brucella, siguiendo la hipótesis del Caballo de Troya. Los monocitos son candidatos sólidos para los depósitos de Brucelos en el BM.Escuela Medicina Veterinari

SARS-CoV-2 infection studies in lung organoids identify TSPAN8 as novel mediator

SARS coronavirus-2 (SARS-CoV-2) is causing a global pandemic with large variation in COVID-19 disease spectrum. SARS-CoV-2 infection requires host receptor ACE2 on lung epithelium, but epithelial underpinnings of variation are largely unknown. We capitalized on comprehensive organoid assays to report remarkable variation in SARS-CoV-2 infection rates of lung organoids from different subjects. Tropism is highest for TUBA- and MUC5AC-positive organoid cells, but levels of TUBA-, MUC5A-, or ACE2- positive cells do not predict infection rate. We identify surface molecule Tetraspanin 8 (TSPAN8) as novel mediator of SARS-CoV-2 infection, which is not downregulated by this specific virus. TSPAN8 levels, prior to infection, strongly correlate with infection rate and TSPAN8-blocking antibodies diminish SARS-CoV-2 infection. We propose TSPAN8 as novel functional biomarker and potential therapeutic target for COVID-19

Advances in Animal Models and Cutting-Edge Research in Alternatives: Proceedings of the Third International Conference on 3Rs Research and Progress, Vishakhapatnam, 2022.

Animal experimentation has been integral to drug discovery and development and safety assessment for many years, since it provides insights into the mechanisms of drug efficacy and toxicity (e.g. pharmacology, pharmacokinetics and pharmacodynamics). However, due to species differences in physiology, metabolism and sensitivity to drugs, the animal models can often fail to replicate the effects of drugs and chemicals in human patients, workers and consumers. Researchers across the globe are increasingly applying the Three Rs principles by employing innovative methods in research and testing. The Three Rs concept focuses on: the replacement of animal models (e.g. with in vitro and in silico models or human studies), on the reduction of the number of animals required to achieve research objectives, and on the refinement of existing experimental practices (e.g. eliminating distress and enhancing animal wellbeing). For the last two years, Oncoseek Bio-Acasta Health, a 3-D cell culture-based cutting-edge translational biotechnology company, has organised an annual International Conference on 3Rs Research and Progress. This series of global conferences aims to bring together researchers with diverse expertise and interests, and provides a platform where they can share and discuss their research to promote practices according to the Three Rs principles. In November 2022, the 3rd international conference, Advances in Animal Models and Cutting-Edge Research in Al- ternatives, took place at the GITAM University in Vishakhapatnam (AP, India) in a hybrid format (i.e. online and in- person). These conference proceedings provide details of the presentations, which were categorised under five different topic sessions. It also describes a special interactive session on in silico strategies for preclinical research in oncology, which was held at the end of the first day

SARS-CoV-2 infection studies in lung organoids identify TSPAN8 as novel mediator.

SARS coronavirus-2 (SARS-CoV-2) is causing a global pandemic with large variation in COVID-19 disease spectrum. SARS-CoV-2 infection requires host receptor ACE2 on lung epithelium, but epithelial underpinnings of variation are largely unknown. We capitalized on comprehensive organoid assays to report remarkable variation in SARS-CoV-2 infection rates of lung organoids from different subjects. Tropism is highest for TUBA- and MUC5AC-positive organoid cells, but levels of TUBA-, MUC5A-, or ACE2-positive cells do not predict infection rate. We identify surface molecule Tetraspanin 8 (TSPAN8) as novel mediator of SARS-CoV-2 infection, which is not downregulated by this specific virus. TSPAN8 levels, prior to infection, strongly correlate with infection rate and TSPAN8-blocking antibodies diminish SARS-CoV-2 infection. We propose TSPAN8 as novel functional biomarker and potential therapeutic target for COVID-19