SARS-CoV-2-related bat virus behavior in human-relevant models sheds light on the origin of COVID-19.

Bat sarbecovirus BANAL-236 is highly related to SARS-CoV-2 and infects human cells, albeit lacking the furin cleavage site in its spike protein. BANAL-236 replicates efficiently and pauci-symptomatically in humanized mice and in macaques, where its tropism is enteric, strongly differing from that of SARS-CoV-2. BANAL-236 infection leads to protection against superinfection by a virulent strain. We find no evidence of antibodies recognizing bat sarbecoviruses in populations in close contact with bats in which the virus was identified, indicating that such spillover infections, if they occur, are rare. Six passages in humanized mice or in human intestinal cells, mimicking putative early spillover events, select adaptive mutations without appearance of a furin cleavage site and no change in virulence. Therefore, acquisition of a furin site in the spike protein is likely a pre-spillover event that did not occur upon replication of a SARS-CoV-2-like bat virus in humans or other animals. Other hypotheses regarding the origin of the SARS-CoV-2 should therefore be evaluated, including the presence of sarbecoviruses carrying a spike with a furin cleavage site in bats.

Liver-resident macrophage necroptosis orchestrates type 1 microbicidal inflammation and type-2-mediated tissue repair during bacterial infection.

Kupffer cells, the phagocytes of fetal origin that line the liver sinusoids, are key contributors of host defense against enteroinvasive bacteria. Here, we found that infection by Listeria monocytogenes induced the early necroptotic death of Kupffer cells, which was followed by monocyte recruitment and an anti-bacterial type 1 inflammatory response. Kupffer cell death also triggered a type 2 response that involved the hepatocyte-derived alarmin interleukin-33 (IL-33) and basophil-derived interleukin-4 (IL-4). This led to the alternative activation of the monocyte-derived macrophages recruited to the liver, which thereby replaced ablated Kupffer cells and restored liver homeostasis. Kupffer cell death is therefore a key signal orchestrating type 1 microbicidal inflammation and type-2-mediated liver repair upon infection. This indicates that beyond the classical dichotomy of type 1 and type 2 responses, these responses can develop sequentially in the context of a bacterial infection and act interdependently, orchestrating liver immune responses and return to homeostasis, respectively.

Penicillium and Talaromyces spp. emerging pathogens in dogs since 1990s.

Penicillium and Talaromyces spp. are environmental saprophytic molds rarely encountered as infectious agents in humans and animals. This article summarizes the clinical features, treatment, and outcomes of proven infections caused by Penicillium or Talaromyces in four dogs in France. Two dogs had disseminated infections, while the other two had a localized form. All dogs had positive histopathological results showing the presence of hyaline septate hyphae and a positive fungal culture with typical Penicillium conidiophores. Talaromyces georgiensis (n = 1), Penicillium labradorum (n = 2), and Penicillium from section Ramosa series Raistrickiorum (n = 1), were identified based on Internal Transcribed Spacer (ITS) Sanger sequencing. The dogs were initially treated with ketoconazole or itraconazole. Second-line treatment was initiated in three dogs, but after several relapses, the prognosis remained poor. Since the 1990s, 18 cases of Penicillium or Talaromyces infections in dogs have been described worldwide. This series of four reports brings new cases to those already reported in the literature, which are probably underestimated in the world.

Penicillium and Talaromyces spp. are molds found in the environment that rarely cause infections in humans and animals. This article summarizes the clinical features and treatment of proven infections caused by Penicillium or Talaromyces species in four dogs in France.

Topological data analysis reveals genotype-phenotype relationships in primary ciliary dyskinesia.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a heterogeneous inherited disorder caused by mutations in approximately 50 cilia-related genes. PCD genotype-phenotype relationships have mostly arisen from small case series because existing statistical approaches to investigating relationships have been unsuitable for rare diseases. METHODS: We applied a topological data analysis (TDA) approach to investigate genotype-phenotype relationships in PCD. Data from separate training and validation cohorts included 396 genetically defined individuals carrying pathogenic variants in PCD genes. To develop the TDA models, 12 clinical and diagnostic variables were included. TDA-driven hypotheses were subsequently tested using traditional statistics. RESULTS: Disease severity at diagnosis, measured by forced expiratory volume in 1 s (FEV1) z-score, was significantly worse in individuals with CCDC39 mutations (compared to other gene mutations) and better in those with DNAH11 mutations; the latter also reported less neonatal respiratory distress. Patients without neonatal respiratory distress had better preserved FEV1 at diagnosis. Individuals with DNAH5 mutations were phenotypically diverse. Cilia ultrastructure and beat pattern defects correlated closely to specific causative gene groups, confirming these tests can be used to support a genetic diagnosis. CONCLUSIONS: This large scale, multi-national study presents PCD as a syndrome with overlapping symptoms and variations in phenotype according to genotype. TDA modelling confirmed genotype-phenotype relationships reported by smaller studies (e.g. FEV1 worse with CCDC39 mutation) and identified new relationships, including FEV1 preservation with DNAH11 mutations and diversity of severity with DNAH5 mutations.

A human immune system mouse model with robust lymph node development.

Lymph nodes (LNs) facilitate the cellular interactions that orchestrate immune responses. Human immune system (HIS) mice are powerful tools for interrogation of human immunity but lack secondary lymphoid tissue (SLT) as a result of a deficiency in Il2rg-dependent lymphoid tissue inducer cells. To restore LN development, we induced expression of thymic-stromal-cell-derived lymphopoietin (TSLP) in a Balb/c Rag2-/-Il2rg-/-SirpaNOD (BRGS) HIS mouse model. The resulting BRGST HIS mice developed a full array of LNs with compartmentalized human B and T cells. Compared with BRGS HIS mice, BRGST HIS mice have a larger thymus, more mature B cells, and abundant IL-21-producing follicular helper T (TFH) cells, and show enhanced antigen-specific responses. Using BRGST HIS mice, we demonstrated that LN TFH cells are targets of acute HIV infection and represent a reservoir for latent HIV. In summary, BRGST HIS mice reflect the effects of SLT development on human immune responses and provide a model for visualization and interrogation of regulators of immunity.

Genetic Diversity of Collaborative Cross Mice Controls Viral Replication, Clinical Severity, and Brain Pathology Induced by Zika Virus Infection, Independently of Oas1b.

The explosive spread of Zika virus (ZIKV) has been associated with major variations in severe disease and congenital afflictions among infected populations, suggesting an influence of host genes. We investigated how genome-wide variants could impact susceptibility to ZIKV infection in mice. We first describe that the susceptibility of Ifnar1-knockout mice is largely influenced by their genetic background. We then show that Collaborative Cross (CC) mice, which exhibit a broad genetic diversity, in which the type I interferon receptor (IFNAR) was blocked by an anti-IFNAR antibody expressed phenotypes ranging from complete resistance to severe symptoms and death, with large variations in the peak and the rate of decrease in the plasma viral load, in the brain viral load, in brain histopathology, and in the viral replication rate in infected cells. The differences in susceptibility to ZIKV between CC strains correlated with the differences in susceptibility to dengue and West Nile viruses between the strains. We identified highly susceptible and resistant mouse strains as new models to investigate the mechanisms of human ZIKV disease and other flavivirus infections. Genetic analyses revealed that phenotypic variations are driven by multiple genes with small effects, reflecting the complexity of ZIKV disease susceptibility in the human population. Notably, our results rule out the possibility of a role of the Oas1b gene in the susceptibility to ZIKV. Altogether, the findings of this study emphasize the role of host genes in the pathogeny of ZIKV infection and lay the foundation for further genetic and mechanistic studies.IMPORTANCE In recent outbreaks, ZIKV has infected millions of people and induced rare but potentially severe complications, including Guillain-Barré syndrome and encephalitis in adults. While several viral sequence variants were proposed to enhance the pathogenicity of ZIKV, the influence of host genetic variants in mediating the clinical heterogeneity remains mostly unexplored. We addressed this question using a mouse panel which models the genetic diversity of the human population and a ZIKV strain from a recent clinical isolate. Through a combination of in vitro and in vivo approaches, we demonstrate that multiple host genetic variants determine viral replication in infected cells and the clinical severity, the kinetics of blood viral load, and brain pathology in mice. We describe new mouse models expressing high degrees of susceptibility or resistance to ZIKV and to other flaviviruses. These models will facilitate the identification and mechanistic characterization of host genes that influence ZIKV pathogenesis.

Central nervous system candidiasis beyond neonates: Lessons from a nationwide study.

Though candidiasis is the most frequent invasive fungal infection, Candida spp. central nervous system (CNS) infections are rare but severe. To further describe clinico-patho-radiological presentations of this entity, we report a retrospective study from January 2005 to December 2018 including patients aged ≥ 28 days with proven or probable CNS candidiasis in France. Twenty-four patients were included. Seventeen patients (70%) had CNS localization secondary to disseminated candidiasis (10 with hematologic malignancies [HM]; the seven other patients had infective endocarditis [IE]). Among patients with HM, seven previously had lumbar puncture for intrathecal chemotherapy, the three others had IE. Among patients with disseminated infection, magnetic resonance imaging (MRI) evidenced meningitis (17%), micro-abscesses (58%), or vascular complications (67%). Seven patients (30%) had isolated CNS involvement related to neurosurgery (n = 2), CARD9 deficiency (n = 2), intravenous drug use, diabetes mellitus, or no identified predisposing condition (n = 1 each). All evaluated patients with isolated CNS involvement had meningitis on cerebrospinal fluid (CSF) and intracranial hypertension. For the latter patients, MRI evidenced meningitis (71%) or abscesses (57%). Among all patients, cerebrospinal fluid (CSF) culture grew Candida spp. in 31% of cases. CSF ßDGlucan or mannan Ag were positive in respectively 86% and 80% of cases. Mortality attributed to CNS candidiasis was 42%: 53% in case of disseminated infection (70% for HM) and 14% in case of localized infection. CNS candidiasis are isolated or occur during disseminated infection in patients with HM and lumbar puncture for intrathecal chemotherapy or during IE. Clinical, radiological finding and outcome highly vary according to CNS localized versus disseminated candidiasis. LAY SUMMARY: Candida is a yeast and is the most common cause of fungal infections worldwide. Candida central nervous system (CNS) infections are rare, severe, and poorly described. We report a retrospective study from January 2005 to December 2018 including patients aged ≥ 28 days with proven or probable CNS candidiasis in France. Twenty-four patients were included (14 men, median age 51 years). Seventeen patients had CNS localization secondary to disseminated candidiasis from blood to CNS (10 with hematologic malignancies [HM], the seven other patients had infective endocarditis [IE]). Seven patients had isolated CNS involvement related to neurosurgery (n = 2), CARD9 deficiency (n = 2), intravenous drug use (n = 1), diabetes mellitus (n = 1), or no identified risk factor (n = 1).During Candida CNS infections, brain lesions were meningitis abscesses or vascular complications. Cerebrospinal fluid (CSF) culture grew Candida spp. in 31% of cases. Forty-two percent of patients died from infection: 53% in case of disseminated infection (70% for HM) and 14% in case of localized infection.

USF1 defect drives p53 degradation during Helicobacter pylori infection and accelerates gastric carcinogenesis.

OBJECTIVE: Helicobacter pylori (Hp) is a major risk factor for gastric cancer (GC). Hp promotes DNA damage and proteasomal degradation of p53, the guardian of genome stability. Hp reduces the expression of the transcription factor USF1 shown to stabilise p53 in response to genotoxic stress. We investigated whether Hp-mediated USF1 deregulation impacts p53-response and consequently genetic instability. We also explored in vivo the role of USF1 in gastric carcinogenesis. DESIGN: Human gastric epithelial cell lines were infected with Hp7.13, exposed or not to a DNA-damaging agent camptothecin (CPT), to mimic a genetic instability context. We quantified the expression of USF1, p53 and their target genes, we determined their subcellular localisation by immunofluorescence and examined USF1/p53 interaction. Usf1-/- and INS-GAS mice were used to strengthen the findings in vivo and patient data examined for clinical relevance. RESULTS: In vivo we revealed the dominant role of USF1 in protecting gastric cells against Hp-induced carcinogenesis and its impact on p53 levels. In vitro, Hp delocalises USF1 into foci close to cell membranes. Hp prevents USF1/p53 nuclear built up and relocates these complexes in the cytoplasm, thereby impairing their transcriptional function. Hp also inhibits CPT-induced USF1/p53 nuclear complexes, exacerbating CPT-dependent DNA damaging effects. CONCLUSION: Our data reveal that the depletion of USF1 and its de-localisation in the vicinity of cell membranes are essential events associated to the genotoxic activity of Hp infection, thus promoting gastric carcinogenesis. These findings are also of clinical relevance, supporting USF1 expression as a potential marker of GC susceptibility.

Aspergillus felis in Patient with Chronic Granulomatous Disease.

We report a case of Aspergillus felis infection in a patient with chronic granulomatous disease who had overlapping features of invasive pulmonary aspergillosis and allergic bronchopulmonary aspergillosis. Identifying the species responsible for aspergillosis by molecular methods can be crucial for directing patient management and selection of appropriate antifungal agents.

Lichtheimia corymbifera Colonization Leading to Pulmonary Infection Can Be Prevented with Liposomal Amphotericin B in a New Murine Model.

The incidence of pulmonary mucormycosis is constantly increasing, especially in hematological patients staying in high-efficiency particulate air-filtered rooms. Pulmonary inhalation of spores may occur outside the hospital, leading to invasive disease once patients received chemotherapies. We developed a new pulmonary mucormycosis mouse model mimicking the expected pathophysiology in human to study antifungal drugs. Naive mice were inoculated intratracheally with Lichtheimia corymbifera spores. After 3 days, mice received corticosteroids and cyclophosphamide and secondarily developed the disease, while only 5% of the initial inoculum was present in the lungs at day 3. Lung colonization with L. corymbifera spores in immunocompetent mice can last at least 44 days. Antifungal drug was administered the day of immunosuppression. Injection of a single 15 mg/kg of body weight dose of liposomal amphotericin B significantly improved survival and pulmonary fungal burden compared with controls, whereas 80 mg/kg oral posaconazole did not. These results show that a unique dose of liposomal amphotericin B offers a real potential decolonization treatment to prevent infection in our mouse model of L. corymbifera lung colonization followed by lung infection.

Microglial production of quinolinic acid as a target and a biomarker of the antidepressant effect of ketamine.

Major depressive disorder is a complex multifactorial condition with a so far poorly characterized underlying pathophysiology. Consequently, the available treatments are far from satisfactory as it is estimated that up to 30% of patients are resistant to conventional treatment. Recent comprehensive evidence has been accumulated which suggests that inflammation may be implied in the etiology of this disease. Here we investigated ketamine as an innovative treatment strategy due to its immune-modulating capacities. In a murine model of LPS-induced depressive-like behavior we demonstrated that a single dose of ketamine restores the LPS-induced depressive-like alterations. These behavioral effects are associated with i/ a reversal of anxiety and reduced self-care, ii/ a decrease in parenchymal cytokine production, iii/ a modulation of the microglial reactivity and iv/ a decrease in microglial quinolinic acid production that is correlated with plasmatic peripheral production. In a translational approach, we show that kynurenic acid to quinolinic acid ratio is a predictor of ketamine response in treatment-resistant depressed patients and that the reduction in quinolinic acid after a ketamine infusion is a predictor of the reduction in MADRS score. Our results suggest that microglia is a key therapeutic target and that quinolinic acid is a biomarker of ketamine response in major depressive disorder.

A Novel Polyaminocarboxylate Compound To Treat Murine Pulmonary Aspergillosis by Interfering with Zinc Metabolism.

Aspergillus fumigatus can cause pulmonary aspergillosis in immunocompromised patients and is associated with a high mortality rate due to a lack of reliable treatment options. This opportunistic pathogen requires zinc in order to grow and cause disease. Novel compounds that interfere with fungal zinc metabolism may therefore be of therapeutic interest. We screened chemical libraries containing 59,223 small molecules using a resazurin assay that compared their effects on an A. fumigatus wild-type strain grown under zinc-limiting conditions and on a zinc transporter knockout strain grown under zinc-replete conditions to identify compounds affecting zinc metabolism. After a first screen, 116 molecules were selected whose inhibitory effects on fungal growth were further tested by using luminescence assays and hyphal length measurements to confirm their activity, as well as by toxicity assays on HeLa cells and mice. Six compounds were selected following a rescreening, of which two were pyrazolones, two were porphyrins, and two were polyaminocarboxylates. All three groups showed good in vitro activity, but only one of the polyaminocarboxylates was able to significantly improve the survival of immunosuppressed mice suffering from pulmonary aspergillosis. This two-tier screening approach led us to the identification of a novel small molecule with in vivo fungicidal effects and low murine toxicity that may lead to the development of new treatment options for fungal infections by administration of this compound either as a monotherapy or as part of a combination therapy.

[Practices in infectious pathology in France in 2015. Results of the national survey]. / Pratique de la pathologie infectieuse en France en 2015. Résultats d'un questionnaire national.

Pathologists have been, are and will be always implicated in the diagnosis of infectious and tropical diseases. The resurgence of opportunistic infections due to the development of immunosuppressive drugs, the increase of migratory involvements draining tropical infections and the last epidemics spotlight the importance of pathologists in the field of infectious diseases. However, cancer is nowadays the first preoccupation of pathologists, which is constantly subject to evaluate diagnostic and prognostic markers and factors predictive to targeted therapy response or immunotherapy. As tumor pathology, infectious diseases require more sophisticated and rapidly changing complementary techniques, appraisals and perhaps a national network of diagnosis. The infectious pathology club committee carries out here a census of methods used in the diagnosis of infectious diseases in France in 2015 and particularly the different techniques used by laboratories to perform infectious diseases diagnosis. This will lay down the foundation of a future national organization of the infectious pathology in providing efficient services (diagnostic support, complementary tools) for the community of French pathologists in this specific domain of competence.

Thalidomide for steroid-dependent chronic disseminated candidiasis after stem cell transplantation: A case report.

Chronic disseminated candidiasis (CDC) is a rare and difficult-to-treat invasive fungal disease occurring mainly after prolonged and profound neutropenia. We describe the case of a 59-year-old man successfully treated with thalidomide for CDC recurrences after an autologous transplantation. We add evidence of the effectiveness of immunomodulatory drugs to manage inflammatory reconstitution immune syndrome-related refractory CDC.

Physical Sequestration of Bacillus anthracis in the Pulmonary Capillaries in Terminal Infection.

The lung is the terminal target of Bacillus anthracis before death, whatever the route of infection (cutaneous, inhalational, or digestive). During a cutaneous infection in absence of toxins, we observed encapsulated bacteria colonizing the alveolar capillary network, bacteria and hemorrhages in alveolar and bronchiolar spaces, and hypoxic foci in the lung (endothelial cells) and brain (neurons and neuropil). Circulating encapsulated bacteria were as chains of approximately 13 µm in length. Bacteria of such size were immediately trapped within the lung capillary network, but bacteria of shorter length were not. Controlling lung-targeted pathology would be beneficial for anthrax treatment.

Deficiency of multidrug resistance 2 contributes to cell transformation through oxidative stress.

Multidrug resistance 2 (Mdr2), also called adenosine triphosphate-binding cassette B4 (ABCB4), is the transporter of phosphatidylcholine (PC) at the canalicular membrane of mouse hepatocytes, which plays an essential role for bile formation. Mutations in human homologue MDR3 are associated with several liver diseases. Knockout of Mdr2 results in hepatic inflammation, liver fibrosis and hepatocellular carcinoma (HCC). Whereas the pathogenesis in Mdr2 (-/-) mice has been largely attributed to the toxicity of bile acids due to the absence of PC in the bile, the question of whether Mdr2 deficiency per se perturbs biological functions in the cell has been poorly addressed. As Mdr2 is expressed in many cell types, we used mouse embryonic fibroblasts (MEF) derived from Mdr2 (-/-) embryos to show that deficiency of Mdr2 increases reactive oxygen species accumulation, lipid peroxidation and DNA damage. We found that Mdr2 (-/-) MEFs undergo spontaneous transformation and that Mdr2 (-/-) mice are more susceptible to chemical carcinogen-induced intestinal tumorigenesis. Microarray analysis in Mdr2-/- MEFs and cap analysis of gene expression in Mdr2 (-/-) HCCs revealed extensively deregulated genes involved in oxidation reduction, fatty acid metabolism and lipid biosynthesis. Our findings imply a close link between Mdr2 (-/-) -associated tumorigenesis and perturbation of these biological processes and suggest potential extrahepatic functions of Mdr2/MDR3.

Deep dermatophytosis and inherited CARD9 deficiency.

BACKGROUND: Deep dermatophytosis is a severe and sometimes life-threatening fungal infection caused by dermatophytes. It is characterized by extensive dermal and subcutaneous tissue invasion and by frequent dissemination to the lymph nodes and, occasionally, the central nervous system. The condition is different from common superficial dermatophyte infection and has been reported in patients with no known immunodeficiency. Patients are mostly from North African, consanguineous, multiplex families, which strongly suggests a mendelian genetic cause. METHODS: We studied the clinical features of deep dermatophytosis in 17 patients with no known immunodeficiency from eight unrelated Tunisian, Algerian, and Moroccan families. Because CARD9 (caspase recruitment domain-containing protein 9) deficiency has been reported in an Iranian family with invasive fungal infections, we also sequenced CARD9 in the patients. RESULTS: Four patients died, at 28, 29, 37, and 39 years of age, with clinically active deep dermatophytosis. No other severe infections, fungal or otherwise, were reported in the surviving patients, who ranged in age from 37 to 75 years. The 15 Algerian and Tunisian patients, from seven unrelated families, had a homozygous Q289X CARD9 allele, due to a founder effect. The 2 Moroccan siblings were homozygous for the R101C CARD9 allele. Both alleles are rare deleterious variants. The familial segregation of these alleles was consistent with autosomal recessive inheritance and complete clinical penetrance. CONCLUSIONS: All the patients with deep dermatophytosis had autosomal recessive CARD9 deficiency. Deep dermatophytosis appears to be an important clinical manifestation of CARD9 deficiency. (Funded by Agence Nationale pour la Recherche and others.).

Absence of Fungal Spore Internalization by Bronchial Epithelium in Mouse Models Evidenced by a New Bioimaging Approach and Transmission Electronic Microscopy.

Clinical data and experimental studies suggest that bronchial epithelium could serve as a portal of entry for invasive fungal infections. We therefore analyzed the interactions between molds and the bronchial/bronchiolar epithelium at the early steps after inhalation. We developed invasive aspergillosis (Aspergillus fumigatus) and mucormycosis (Lichtheimia corymbifera) murine models that mimic the main clinical risk factors for these infections. Histopathology studies were completed with a specific computer-assisted morphometric method to quantify bronchial and alveolar spores and with transmission electron microscopy. Morphometric analysis revealed a higher number of bronchial/bronchiolar spores for A. fumigatus than L. corymbifera. The bronchial/bronchiolar spores decreased between 1 and 18 hours after inoculation for both fungi, except in corticosteroid-treated mice infected with A. fumigatus, suggesting an effect of cortisone on bronchial spore clearance. No increase in the number of spores of any species was observed over time at the basal pole of the epithelium, suggesting the lack of transepithelial crossing. Transmission electron microscopy did not show spore internalization by bronchial epithelial cells. Instead, spores were phagocytized by mononuclear cells on the apical pole of epithelial cells. Early epithelial internalization of fungal spores in vivo cannot explain the bronchial/bronchiolar epithelium invasion observed in some invasive mold infections. The bioimaging approach provides a useful means to accurately enumerate and localize the fungal spores in the pulmonary tissues.

Structural and Functional Alterations of Skeletal Muscle Microvasculature in Dystrophin-Deficient mdx Mice.

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease, caused by an absence of dystrophin, inevitably leading to death. Although muscle lesions are well characterized, blood vessel alterations that may have a major impact on muscle regeneration remain poorly understood. Our aim was to elucidate alterations of the vascular network organization, taking advantage of Flk1(GFP/+) crossed with mdx mice (model for human DMD where all blood vessels express green fluorescent protein) and functional repercussions using in vivo nuclear magnetic resonance, combining arterial spin-labeling imaging of perfusion, and (31)P-spectroscopy of phosphocreatine kinetics. For the first time, our study focused on old (12-month-old) mdx mice, displaying marked chronic muscle lesions, similar to the lesions observed in human DMD, in comparison to young-adult (3-month-old) mdx mice displaying only mild muscle lesions with no fibrosis. By using an original approach combining a specific animal model, state-of-the-art histology/morphometry techniques, and functional nuclear magnetic resonance, we demonstrated that the microvascular system is almost normal in young-adult in contrast to old mdx mice, displaying marked microvessel alterations, and the functional repercussions on muscle perfusion and bioenergetics after a hypoxic stress vary depending on stage of pathology. This original approach clarifies disease evolution and paves the way for setting up new diagnostic markers or therapeutic strategies.

Sumoylation controls host anti-bacterial response to the gut invasive pathogen Shigella flexneri.

Shigella flexneri, the etiological agent of bacillary dysentery, invades the human colonic epithelium and causes its massive inflammatory destruction. Little is known about the post-translational modifications implicated in regulating the host defense pathway against Shigella. Here, we show that SUMO-2 impairs Shigella invasion of epithelial cells in vitro. Using mice haploinsufficient for the SUMO E2 enzyme, we found that sumoylation regulates intestinal permeability and is required to restrict epithelial invasion and control mucosal inflammation. Quantitative proteomics reveals that Shigella infection alters the sumoylation status of a restricted set of transcriptional regulators involved in intestinal functions and inflammation. Consistent with this, sumoylation restricts the pro-inflammatory transcriptional response of Shigella-infected guts. Altogether, our results show that the SUMO pathway is an essential component of host innate protection, as it reduces the efficiency of two key steps of shigellosis: invasion and inflammatory destruction of the intestinal epithelium.