Chronic inflammatory systemic diseases (CIDs) are a burden to humans because of life-long debilitating illness, increased mortality and high therapy costs. CIDs’ increasing prevalence in western countries has indeed placed them at the third rank of morbi-mortality causes. Unfortunately, available treatments are poorly targeted and non-curative. That is partly linked to a complex and largely ununderstood pathophysiology. Genetic susceptibility clearly plays a role. Genes linked to the immune system have been identified, but causal genes remain mostly unknown and other factors such as intestinal microbiota have also been implicated. The complexity of CIDs’ pathophysiology suggests that a holistic approach is the most susceptible to help make significant progress. Our project intends to take advantage of recent technical progress and development of informatics tools to set up a transversal approach. High-resolution sequencing technology indeed quickly produces large amounts of accurate data. Besides, new integrative informatics tools allowing storage and integrative analysis of this resulting high amount of data are now available. We intend to set-up a CID’s network allowing the gathering and extensive analysis of data related to immuno-genetic determinants, immune repertoire and microbiota from individuals suffering from one of the three major interlinked CIDs, namely Hidradenitis Suppurativa (HS), Crohn’s disease (CD) and Spondyloarthropathy (SpA) as compared to healthy volunteers.

It has been shown that methylation can act as a kind of memory of the immune system. For patients with co-infections, it is of particular importance to know when to begin an anti-retroviral therapy, especially if they are already infected with tuberculosis. The goal of this study is to find hyper or hypo methylated loci related to the reaction of HIV patients (co-infected or not) to different kind of treatments.

This project aims at identifying novel genetic traits that regulate the anti-tumor activities of NK cells and homeostasis of NK cells and other ILC using an unique mouse resource, the Collaborative Cross (CC). CC is a panel of recombinant inbred mice derived from randomized breeding of eight laboratory inbred strains combining high genetic diversity with the advantage of inbred mouse strains. We have identified CC strains that diverge in their anti-tumor immune responses and are characterizing the molecular mechanisms responsible for these differences. Ultimately, these diverse genetic traits may lead to the development of novel therapies for cancer.

Taking advantage of a murine model of controlled microbiota composed of 12 strains, we evaluated the activity of a cocktail of three virulent bacteriophages to target a murine Escherichia coli strain in the mammalian gut.

In this project we study ecological diversification of Klebsiella pneumoniae and closely related species. Using comparative genomics we want to identify the pattern of genome adaptation to different environments

Anti-TNF therapy has revolutionized treatment of many chronic inflammatory diseases, including rheumatoid arthritis, Crohn’s disease and spondyloarthritis (SpA). However, clinical efficacy of TNF-inhibitors (TNFi) is limited by a high rate of non-responsiveness (30-40%) both in SpA and other diseases, exposing a substantial fraction of patients to important side-effects without any clinical benefit. Despite the extensive use of TNFi since many years, it is still not possible to determine which patients will respond to TNFi before treatment initiation. In this study, we have tested the hypothesis that the functional analysis of immune responses may not only improve our understanding of the molecular mechanisms of TNF-blocker activity, but also identify correlates of therapeutic responses in SpA patients. To facilitate the potential translation of our findings into a clinical setting, we have used standardized whole-blood stimulation assays (“TruCulture” assays, Duffy et al., Immunity 2014), and have minimized sources of pre-analytical variability, implementing a highly sensitive and robust pipeline to assess immune functions in patients. To investigate the concept that the immune status of a patient will define their response to TNFi treatment, we have used machine-learning algorithms to identify, in whole-blood stimulation assays, immunological transcripts that correlate with clinical efficacy of TNFi. Our results obtained with a cohort of 67 SpA patients demonstrate that high expression, before treatment initiation, of molecules associated with leukocyte invasion/migration and inflammatory processes predisposes to favorable outcome of anti-TNF therapy, while high-level expression of cytotoxic molecules was associated with poor therapeutic responses to TNF-blockers. These findings may suggest that SpA patients whose immune response is characterized by strong, NF-kB-mediated inflammation are more likely to benefit from TNFi treatment than patients with an active T/NK-cell component. Unfortunately our manuscript describing these results has been rejected by Nature Medicine. However, in her letter the editor mentioned, “Should future experimental data allow you to demonstrate that the identified gene signatures predict response to treatment and outperform previously reported approaches in an independent cohort, we would be happy to look at a new submission…”. We have recruited additional SpA patients over the summer and we are currently in the process of performing the gene expression analysis. The goal of this bioinformatic analysis will be to identify transcripts in stimulated immune cells that predict therapeutic outcome in a training set of patients using machine-learning algorithms and validate the findings in a replication cohort.

Mitochondria are double-membrane bound organelles that are essential in every tissue of the body. They are metabolic hubs and signalling platforms that are deeply integrated into cellular homeostasis. The functions of mitochondria are intimately linked to their form, which is regulated by a balance of membrane fusion and fission: dynamin-like GTPases OPA1 and MFN1/2 perform membrane fusion and DRP1 regulates membrane fission. Mutations in mitochondrial genes cause a pleiotropic spectrum of clinical disorders whose underlying genetic, morphological and biochemical defects can be easily studied in skin fibroblasts generated from patient biopsies. The morphology of mitochondria is inextricably linked to its many essential functions in the cell and we are interested in understanding the relationship between mitochondrial shape changes and metabolism in the context of acquired and inborn human diseases. Balanced fusion and fission events shape mitochondria to meet metabolic demands and to ensure removal of damaged organelles. Mitochondrial fragmentation occurs in response to nutrient excess and cellular dysfunction and has been observed in mitochondrial genetic diseases and is thought to play an important role in the development of disease. The physiological relevance of mitochondrial morphology and the mechanisms that regulate mitochondrial dynamics are incomplete and so we have set out to find ways to rebalance mitochondrial dynamics in genetic diseases. We recently developed imaging and informatics pipelines to allow for the automated, rapid, reliable quantification of mitochondrial morphology in human fibroblasts. We applied this new technology in the context of genome-wide siRNA screens in immortalized fibroblasts from an OPA1 patient with dominant optic atrophy and control fibroblasts to identify candidate genes able to reverse the mitochondrial fragmentation phenotype associated with mitochondrial dysfunction in patient cells. We have performed the same genome-wide screen in healthy immortalized control fibroblasts. Together, these studies will help us identify lists of genetic modifiers and therapeutic targets that can be investigated further using cell biology and biochemical tools in the lab.

Our goal is to have a bioinformatic tool that performs the 2 x 2 comparison of matrices of numbers in matrix batches. Each matrix corresponds to the use of gene fragments (V or J) to create a re-arranged gene (VJ) encoding a specific antibody, identified by droplet microfluidic or flow cytometry techniques followed by high throughput sequencing (NGS). ). The matrices are made for the two chains encoding the specificity of an antibody: the heavy chain (VH) or the light chain (VL). The goal is to compare VH matrices one against another, and VL matrices one against another for antibody gene rearrangements in mice, llama, and humans.

This project is integrated in the analysis of the gut ecosystem of children implicated in the AFRIBIOTA project, a translational project performed within a consortium of researchers and medical doctors from the Central African Republic, Madagascar, France and Canada (see https://research.pasteur.fr/fr/program_project/the-afribiota-project/). AFRIBIOTA aims at understanding the risk factors and pathophysiological changes underlying chronic child malnutrition as manifested through delayed growth. Within the project submitted, we aim at assessing a possible link between asymptomatic pathogen carriage, gut inflammation and stunted growth of children included in the study site in Antananarivo, Madagascar.

Several bacterial pathogens compromise the barrier function of endothelia by triggering the opening of transendothelial cell macroaperture (TEM) tunnels as large as several micrometres in width. This phenomenon has been linked to the dissemination of Staphylococcus aureus via the haematogenous route. The opening of TEMs occurs in response to the overall relaxation of the actomyosin cytoskeleton and cell spreading-associated with a disruption of focal adhesions via either toxin-induced inhibition of RhoA signaling or increase of the flux of cyclic-AMP broad signaling molecule. The principles of dewetting, i.e. the spontaneous withdrawal of a liquid film from a non-wettable surface by nucleation and growth of dry patches, explain the physical phenomena underpinning the opening of TEM tunnels. For both liquid and cellular dewetting, the growth of holes is governed by a competition between surface forces and line tension that limit the TEM widening. By conducting high-resolution microscopy approaches we unveil the presence of an actomyosin cable encircling TEMs. We have developed a theoretical cellular dewetting framework to interpret TEM physical parameters that are quantitatively determined by laser ablation experiments. We establish the critical role of ezrin and non-muscle myosin II (NMII) in building actin cables along TEM edges to progressively implement line tension that limits TEMs enlargement.

Globally one out of four children under 5 years is affected by linear growth delay (stunting). This syndrome has severe long-term sequelae including increased risk of illness and mortality and delayed psychomotor development. Stunting is a syndrome that is linked to poor nutrition and repeated infections. To date, the treatment of stunted children is challenging as the underlying etiology and pathophysiological mechanisms remain elusive. We hypothesize that pediatric environmental enteropathy (PEE), a chronic inflammation of the small intestine, plays a major role in the pathophysiology of stunting, failure of nutritional interventions and diminished response to oral vaccines, potentially via changes in the composition of the pro- and eukaryotic intestinal communities. The main objective of AFRIBIOTA is to describe the intestinal dysbiosis observed in the context of stunting and to link it to PEE. Secondary objectives include the identification of the broader socio-economic environment and biological and environmental risk factors for stunting and PEE as well as the testing of a set of easy-to-use candidate biomarkers for PEE. We also assess host outcomes including mucosal and systemic immunity and psychomotor development. AFRIBIOTA is a case-control study for stunting recruiting children in Bangui, Central African Republic and in Antananarivo, Madagascar. In each country, 460 children aged 2–5 years with no overt signs of gastrointestinal disease are recruited (260 with no growth delay, 100 moderately stunted and 100 severely stunted). We compare the intestinal microbiota composition (gastric and small intestinal aspirates; feces), the mucosal and systemic immune status and the psychomotor development of children with stunting and/or PEE compared to non-stunted controls. We also perform anthropological and epidemiological investigations of the children’s broader living conditions and assess risk factors using a standardized questionnaire. To date, the pathophysiology and risk factors of stunting and PEE have been insufficiently investigated. AFRIBIOTA will add new insights into the pathophysiology underlying stunting and PEE and in doing so will enable implementation of new biomarkers and design of evidence-based treatment strategies for these two syndromes. These analyses comprise the child development aspects of AFRIBIOTA.

We need an independent statistician to confirm that appropriate statistical tests were used to analyze the data in your manuscript for the final revision of our manuscript in Science Signaling (Manuscript Number: aar3993, \"LGP2 binds PACT to regulate RIG-I- and MDA5-mediated antiviral response\" ). Sincerely yours, Anastassia Komarova

Without new treatment development tuberculosis could cause about 70 million deaths by 2050, mostly due to the spread of multidrug-resistant strains. The standard drug regimen still builds on the first drugs introduced decades ago, and takes 6 months in the case of drug-sensitive tuberculosis, and up to 2 years in the case of drug-resistant tuberculosis, with heavy side effects. This long therapeutic regimen often results in patients not being able to follow it or complete it correctly, which promotes the chronicity of the infection and ultimately the onset of drug resistance. Although a few new molecules have been discovered, improving both the quality and the duration of tuberculosis chemotherapy remain pressing needs. Furthermore, the failure of chemotherapy is not only due to genetic resistance, which takes relatively long to occur, but also to the intrinsic ability of mycobacteria to diversify in discrete phenotypic states, which can endure drugs even in the absence of genetic mutations. This phenomenon, known as persistence, can eventually favor the onset of resistance, with major repercussions on disease control. In sum, tuberculosis therapy presents many challenges and in our view it is critical to study the ability of a drug or a drug combination to sterilize discrete subpopulations, which may either pre-exist in the population or result from adaptive processes. We found that, prior to drug exposure, phenotypically distinct subpopulations exist that display different drug susceptibility. In light of this, we hypothesized that phenotypic variation from cell to cell favors persistence and can consequently bring about treatment failure. Here we aim to identify molecules that reduce phenotypic variation, making the population more uniformly and rapidly susceptible to standard treatment. To this end, we developed a microfluidic system that allows us to track single cells by live imaging and to carry out a screening at the single-cell level, looking for molecules that homogenize the bacterial population and enhance the effectiveness of the standard treatment. Our approach could ultimately offer original therapeutic strategies towards better control of tuberculosis.

Complex chronic diseases are caused by the accumulation of genetic, microbial and lifestyle factors. The number and complexity of such factors makes prediction of pathogenesis and therapy particularly difficult. Although a single factor is rarely sufficient to trigger pathology, genetic and environmental factors have so far been studied in isolation. Nevertheless, a substantial number of genetic variants have been associated with disease risk and the concomitant lifestyle shift and excessive hygiene are thought to contribute to the increased incidence in inflammatory diseases in industrialized countries. Moreover, clinical and experimental observations suggest a strong impact of gut microbiota on susceptibility to inflammatory diseases. The aim of 3D PATH is to explore the multiplicity and complexity of genetic, microbial and lifestyle factors associated with vulnerability to inflammatory pathology, using mice of the Collaborative Cross (CC), that model human genetic variability. Quantitative trait loci analyses, as well as integrative data analyses on metabolic and inflammatory outcomes will reveal new genetic variants and combinations of variants associated with disease susceptibility, and whether alterations of the gut microbiota in genetically susceptible mouse strains can trigger the phenotype. Moreover, the longitudinal design of experiments will allow us to identify early biomarkers that predict the pathology later in life. In a second step, validation of the identified risk factor combinations and exploration of the underlying molecular mechanisms will be performed taking advantage of the mouse model.

The provision of human biological material collected, processed and stored under optimal conditions is crucial to ensure the quality of research carried out downstream. These optimal conditions must be determined by a rational method validation approach taking into account the critical parameters of the different biological sample management processes that are likely to have an impact on their quality.

The therapeutic anti-IgE antibody Omalizumab is used for the treatment of severe asthma, and is known to trigger anaphylaxis in some patients. Since Omalizumab is a humanized IgG1, so we hypothesized that Omalizumab could trigger anaphylaxis through the alternative FcgR-mediated pathway. Indeed, we observed that Omalizumab can trigger anaphylaxis in genetically modified mice expressing human FcgRs. We further produced a mutant version of Omalizumab which can still block IgE but cannot bind FcgRs, and demonstrated that this mutant anti-IgE does not induce FcgR-mediated anaphylaxis.

Hi-C contact maps reflect the relative contact frequencies between pairs of genomic loci, quantified through deep-sequencing. Differential analyses of these maps facilitate downstream biological interpretations. However, the multi-fractal nature of the DNA polymer inside the cellular envelope results in frequency values spanning several orders of magnitude: contacts involving loci pairs at large genomic distance are much sparser compared to closer pairs. The same is true for poorly covered regions such as telomeres and repeated sequences. Poor coverage translates into low signal-to-noise ratios. There is no clear consensus to address this limitation. We present a fast, flexible procedure operating on simple data that takes into account the contacts in each region of a contact map. Binning is performed only when necessary on noisy regions, preserving informative ones. This results in high-quality, low-noise contact maps that can be conveniently visualized for rigorous comparative analyses.

Deconvolution of the polyclonal antibody response targeting HIV-1 allowed the identification of broadly neutralizing monoclonal antibodies (bNAbs) targeting the viral envelope. Infusion of bNAbs protects against HIV-1 acquisition and decreases viral load. bNAbs kill HIV-1-infected cells, modulate host immune responses, and, when associated to latency-reversal agents, delay viral rebound in animal models. These antiviral activities are mediated by the Fc region, which is required for optimal in vivo efficacy. Thus, the landscape of Fc effector functions triggered by bNAbs is under intense investigation. Our aim is to decipher the molecular mechanisms underlying the sensitivity of HIV-1-infected cells to Fc effector functions.

Epidemiological data report an association between obesity and inflammatory bowel disease (IBD). Furthermore, animal models demonstrate that maternal high fat diet (HFD) and maternal obesity increase susceptibility to IBD in offsprings. However, the mechanisms that translate maternal obesity and HFD into increased susceptibility to IBD later in life remain unknown. Here we report that excess calorie intake by neonatal mice, as a consequence of maternal HFD, forced feeding of neonates or low litter competition, leads to multiple causally-linked perturbations in the intestine that imprint the individual with long term susceptibility to IBD.

Adaptive immune cells play important role in pathogenesis of multiple sclerosis by infiltrating the central nervous system, thereby contributing to demyelination and maintenance of an inflammatory microenvironment. In particular, autoreactive T cells, CD4+ T helper and CD8+ T cells exert a detrimental effect, while CD4+ regulatory T cells (Treg) have impaired suppressive function. Interferon b (IFNb), a commonly prescribed treatment for relapsing-remitting multiple sclerosis (RR-MS) decreases relapse rates and brain disability progression. However, around 30% of patients are or become non-responsive to treatment. Our aim is to determine the immune signatures associated with clinical efficacy of IFNb treatment in RRMS patients

The aim of this project is to understand how inherited APC gene mutations affect the immune system of familial adenomatous polyposis patients, and to evaluate the potential contribution of altered immune responses to polyposis and intestinal cancer development in these patients. (see https://research.pasteur.fr/en/project/projet-de-recherche-clinique-impact-des-mutations-du-gene-apc-adenomatous-polyposis-coli-dans-les-reponses-immunes-anti-tumorales/)

Comparison of Microsatellites and Multi Locus Sequences Typing approaches. Fungi: Pneumocytis jirovecii

The transcriptome signature during rabies infection will be analyzed both in animal model (mouse) and in human, at the central nervous system level, to identify the main canonical pathways involved during the infection.

Oral administration is a preferred model for studying infection by bacterial enteropathogens such as Yersinia. In the mouse model, the most frequent method for oral infection consists of oral gavage with a feeding needle directly introduced in the animal stomach via the esophagus. In this study, we compared needle gavage to bread feeding as an alternative mode of bacterial administration.

Parvimonas micra is a gram+ anaerobic coccus bacteria associated with colorectal cancer (CRC). The stool of patients with CRC has higher Parvimonas micra concentration compared to healthy individuals. It is also present in the colonic mucosa of CRC patients. Even if we find it in the adjacent healthy tissue, it is predominantly found in the tumor. Furthermore, it is correlated with the CpG island methylator phenotype (CIMP), a particular subtype of CRC. More specifically, it is associated with the hyper-methylation of tumor suppressor gene promoters. To find out whether this bacteria is involved in the initiation of CRC, we have developed a model of a differentiated epithelial monolayer of human colonic primary cells. After co-culture with this microorganism, we found a significant increase in the global DNA methylation level of the cell genome compared to the bacteria-free control. Now we would like to determine whether this increase in DNA methylation is specific to certain regions of the genome. Therefore, we will use Illumina's Infinium MethylationEPIC BeadChip Kit.

We studied the impact of deletion of different component of a regulatory system on the transcription of specific genes.

The aim of this study is based on the analysis of the transcriptome during the infection with European bat lyssavirus type 1 (EBLV-1) in torpid bat. This study will be conducted using an in vitro model using another bat cell line from an European bat.

Hepatitis C virus (HCV) infection is a slow and asymptomatic progressive liver disease leading to metabolic disorders such as steatosis, an accumulation of lipid droplets (LDs) in hepatocytes. We have assessed the interplay between HCV variants recovered from chronically infected patients and LD content in infected hepatoma cells, through quantitative imaging approaches.

Modulation of infectious diseases transmission by climate conditions must be investigate in Sahel to prevent epidemics. Registration of data on flu transmission and on rainfalls+ temperature was conducted over the last ten years by the Flu national reference center in Niamey. Time series analysis must be conducted to investigate the correlation between the number of cases and climatic conditions.

Immune thrombocytopenia (ITP) is an autoimmune condition characterized by an autoantibody response against platelets, driven by pathogenic plasma cells often found in the spleen. This autoreactive plasma cell population remains poorly characterized, especially in terms of antibody affinity and anatomical distribution. In order to tackle this problem, we have developed a microfluidic platform to characterize platelet-specific plasma cells isolated from ITP patients, in terms of their IgG secretion rate and affinity for a platelet autoantigen at the single-cell level.

The LabEx Milieu interieur (MI) project is a clinical study aiming to define the natural variability of the human immune response. Fibroblasts were prepared from skin biopsies of 300 of the 1000 healthy donors (30 men and 30 women in each of 5 decades from 20 to 69 years) by Genethon. Each primary line is annotated by metadata derived from the systematic genotypic-phenotypic analysis Labex-MI (serology, genomic analyzes, proteomics, transcriptome, microbiota, clinical data and epidemiological selection criteria). The objective is to characterize the innate immune response of fibroblasts from healthy donors. We have developed approaches to obtain standardized measures of the immune response and to identify interindividual variance (Chansard et al., 2021) on a subset of sixteen primary fibroblast lines.. We observed that cell responses to LPS stimulation were distributed between “low” and “high” responders, while inter-donor variability of the response to poly I: C was very low. Poly I: C and LPS activate pathways from TLR3 and TLR4 receptors, respectively. We set up a real-time quantitative PCR assay of the 16 cells in parallel using the BioMark automated PCR system (Fluidigm) for comparative quantification of mRNAs baseline expression in the donors’ fibroblasts to check if low responses to LPS were due to a different expression of TLR4 and other factors of the pathway. We will extend the analysis to stimulated cells by Poly I: C ,LPS and other agonists of the innate immune response and also in parallel to cells infected by Leptospira interrogans.

We seek to make the appropriate statistical comparisons of oxygen consumption and mitochondrial membrane potential measurements in paired, high-resolution respirometry measurements between control and experimental samples

Factors determining RABV tropism are largely unknown. Here, we are identifying the susceptibilities and influence of glial cells on RABV infection.

Using reverse genetics, we produced recombinant viruses within a prototypic HCV strain backbone, by substituting its core coding sequence by the equivalent sequences from from clinical isolates of different HCV genotypes. To verify that heterologous core sequences did not impair cross-talk with prototypic viral elements and could be used for comparative studies, we monitored the viral replication of our set of core intergenotypic viruses. For this, we quantified the amount of intracellular viral RNA, secreted genomes and infectious titers at different time points following infection of hepatoma cells with the recombinant viruses.

New mouse genetic reference populations obtained from 8 distinct founder strains, including 3 wild-derived strains, have been developped since the 2000s and are now available. These populations captured around 95% of the existing murine genetic diversity and constitute a better model than standard inbred laboratory mouse strains. These populations constitute tools to identify new phenotypes and to map the causative genetic variants (QTL mapping) behind these phenotypes. These populations include : i) Collaborative Cross (CC) inbred strains; ii) Recombinant inbred between CCs (CC-RIXs) and iii) Diversity Outbred. These populations are specifically used in the Mouse Genetics Laboratory to identify new variants involved in host susceptiblity differences to pathogens.

This project addresses two main questions: does Chlamydia trachomatis modify glycolysis and/or oxidative phosphorylation in the host, and do the bacteria need these metabolic pathways to complete their developmental cycle.

Bacterial toxins can induce a wide range of life threatening diseases and are at risk of bioweapon development due to their extreme toxicity and ease of production. Some AB-like toxins exploit the host cell endocytic machinery to enter into the cell cytosol where they exert their poisoning effects. Host-targeted therapy involving the development of small molecules interfering with key vesicular trafficking components hijacked by bacterial toxins offers to counteract toxin action. We have identified the small compound C910, in a cell-based High-throughput screen (HTS) followed by orthogonal screens described in (Mahtal N et al., 2018), for its cell-protective activity against CNF1 toxin from pathogenic Escherichia coli, as well as diphtheria and Shiga toxins. Therefore, to characterize C910 mechanism of action and find its cellular target we have realized an siRNA wide-genome screening on primary human cells. This screening aims to find genes that can interfere with the trafficking of the CNF1 toxin.

In recent years, immune dysfunctions, including auto-immune mechanisms and peripheral inflammation, have been clearly associated with severe neuropsychiatric disorders like bipolar disorders (BD) and schizophrenia (SZ). These findings are supported by an extensive litterature highlighting a higher risk to develop neuropsychiatric disorders in patients suffering from auto-immune diseases and also the presence of low-grade inflammation and abnormal immunoglobulin rates in patients with psychosis. It is now well-established, since the description of paraneoplastic and auto-immune encephalitis, that antibodies targeting self-antigens such as membrane receptors or intracellular proteins could trigger psychiatric symptoms and severe inflammation. Therefore, an in-depth characterisation of circulating auto-antibodies and their clinical and/or biological implications has become a critical issue to stratify specific subgroups of patients with auto-immune psychosis in order to adjust and adapt the treatment and care, and develop novel approaches. Nicotinic acetylcholine receptors (nAChRs) have been linked to severe neuropsychiatric disorders by clinical and genome-wide association studies (GWAS). In addition to their key roles in neuronal function, nAChRs are also involved in the complex regulation of immuno-inflammatory processes both in the brain and the periphery, making them prime candidates to study the link between inflammation and major psychiatric disorders. Furthermore, nAChRs have already been identified as the target of autoimmune mechanisms leading to the destruction of the neuromuscular junction in the well-described autoimmune disease, myasthenia gravis. Based on these findings, we have started to dissect auto-immune mechanisms against nAChRs involved in SZ and BD. In brief, anti-nAChR auto-antibodies contribute to cognitive dysfunction and psychotic symptoms through peripheral inflammation. Here, our goals are (1) to extend the current knowledge by dissecting the relationship between clinical features and peripheral inflammation (cytokines, chemokines, ...) (2) to stratify patients with anti-nAChR auto-immune psychosis by using cluster analyse

Vaccines against COVID-19 have been developed for use as homologous two-dose regimens and several of them have demonstrated efficacy. There is limited data on the clinical and the immune response induced by heterologous vaccination regimens (HVR) using alternate vaccine modalities. CORSER-4 is a Viro-Immunology cohort promoted by the Institut Pasteur that will follow-up subjects from the time they receive a prime vaccine dose or a boosting dose. We determined subjects sub-groups of interest defined by the type of vaccine immunization they receive: (i) Heterologous two-dose vaccine regimen, the less frequently used at the moment, (ii) Homologous two-dose vaccine regimen, the more frequently used; (iii) One-dose vaccine regimen and (iv) Infectious-prime vaccine-boost immunization in COVID-19-experienced patients. The subject will be enrolled on the planed last boost injection visit and 5 Follow-up visits will be further conducted (Month1, M3, M6, M12 and M24). We will collect longitudinal clinical data and biological samples. We will explore Viral and Immune Response in sera, nasopharyngeal secretions and in saliva samples. We will assess the immune response obtained by various vaccination regimen against the reference strains and the variants of concern, and the durability of the humoral and cellular response. In addition, we will document any occurring acute infection episode with a supplemental unscheduled visit in order to detect an emerging variant viral strain. Altogether, the CORSER-4 project constitutes an opportunity to evaluate early anti-SARS-CoV-2 immunity in heterologous (and others) vaccine regimens and to estimate their efficacy and their sustainable (M24) protection against circulating virus strains (reference and variants).

Mitochondria are dynamic organelles that undergo constant morphological changes, resulting from fusion and fission events. Mitochondrial fission is crucial for mitochondrial function, apoptosis, mitophagy, and mitochondrial segregation during mitosis. While core mitochondrial fission factors have been elucidated and characterized, it is unclear if additional molecules participate or are main players of the fission process. To solve this question, we setup a genome wide, high content imaging (HCI) screening to identify suppressors of mitochondrial fragmentation in Opa1-/- cells. The principle is that using cells deficient for mitochondrial fusion (ablated for the core fusion protein Opa1), we may identify fission factors by screening for genes for which the loss of function is able to complement Opa1-/- phenotype. This was validated in preliminary experiments of silencing of the core fission protein Drp1, where confocal and electron microscopy confirmed that ablation of Drp1 resulted in mitochondrial elongation in Opa1-/- cells without causing mitochondrial fusion in a classic polyethylene glycol fusion assay. Following miniaturization of the assay, we set up an efficient pipeline to perform an automated HCI screening in Opa1-/- MEFs transfected with a pooled siRNAs library targeting >19,000 genes. Automated imaging and high content image quantification allowed us to generate a list of potential hits, that we aim to process in collaboration with the lab of Timothy Wai and the C3BI HUB, in order to identify promising genes that will be validated and investigated in the future.

We observed that Chlamydia trachomatis infection results in deep changes in the histone methylation profile of the infected cells.