Lymphadenitis due to Histoplasmosis capsulatum var. capsulatum : Unawareness or rare occurrence in the Democratic Republic of Congo? Unusual original report with first immunohistochemical phenotyping of the fungus: Lymphadénite à histoplasma capsulatum var capsulatum. Méconnaissance ou rareté en République Démocratique du Congo ? Cas clinique inhabituel avec caractérisation du fungus par immunohistochimie

We have described herein the first lymphadenitis due to Histoplasma capsulatum var capsulatum with molecular characterization of the pathogen. The patient was a 55-year-old female from a remote village of Yabaondo in the former Province Orientale, currently Tshopo Province, Democratic Republic of Congo (DRC) who presented with multiple swollen left neck lymph nodes. She reported weight loss (undefined) but was otherwise healthy, and a presumptive diagnosis of tuberculosis (TB) was postulated. The biopsy specimen yielded plenty yeast cells of H. capsulatum var capsulatum on Hematoxylin-Eosin routine staining. The molecular identity of the fungus was confirmed by immunohistochemistry at the Pasteur Institute of Paris. The rarity of reported cases of H. capsulatum var capsulatum in DRC prompted us to report this unique case to generate awareness and preparedness of this emerging/reemerging neglected tropical fungal infection against outbreaks. H. capsulatum var capsulatum needs to be considered in the work-up of lymphadenopathies in tropical environment. Nous décrivons le premier cas d’une lymphadénite spécifique histoplasmique à Histoplasma capsulatum var capsulatum. Il s’agissait d’une patiente de 55 ans originaire du village Yabaondo dans l’ancienne Province Orientale, actuellement Province de la Tshopo. Son état général était satisfaisant excepté un amaigrissement et la présence de nombreux ganglions cervicaux gauches de taille variable, présumés tuberculeuses (TB). La biopsie a montré un remaniement de l’architecture folliculaire remplacée par une prolifération de gros macrophages bourrés des spores d’H. capsulatum var capsulatum. L’immunohistochimie utilisant un anticorps spécifique maison a été réalisé à l’Institut Pasteur de Paris et a confirmé l’identité moléculaire du microorganisme. La rareté des cas d’histoplasmose à H. capsulatum en RD Congo nous a motivé à rapporter ce cas inédit afin d’attirer l’attention et de contribuer à la préparation de la lutte contre cette entité émergente/reémergente négligée. L’Histoplasmose à H. capsulatum var capsulatum doit être evoquée dans la demarche de diagnostic differentiel d’une lymphadénopathie en milieu tropical

A humanized mouse model for sequestration of Plasmodium falciparum sexual stages and in vivo evaluation of gametocytidal drugs

The development of new drugs to disrupt malaria transmission requires the establishment of an in vivo model to address the biology of Plasmodium falciparum sexual stages (gametocytes). Herein we show that chemically immune-modulated NSG mice grafted with human erythrocytes support complete sexual development of P. falciparum parasites and generate high gametocytemia. Immunohistochemistry and RT-qPCR analyses indicate an enrichment of immature gametocytes in the bone marrow and the spleen, suggesting a sequestration mechanism reminiscent to that observed in humans. Upon primaquine treatment, elimination of gametocytes from peripheral blood and from sequestration sites was observed, providing a proof of concept that these mice can be used for testing drugs. Therefore, this model allows the investigation of P. falciparum sexual commitment, gametocyte interactions with the bone marrow and spleen and provides the missing link between current in vitro assays and Phase I trials in humans for testing new malaria gametocytidal drugs

Cell therapy of Duchenne muscular dystrophy: preclinical trial in GRMD dogs

Duchenne muscular dystrophy (DMD), a genetic progressive X-linked muscular dystrophy, is the most common genetic disease in humans. Cell therapy based on the use of somatic stem cells is a very promising approach. In a dog myopathy model, we isolated a muscle stem cell (MuStem) with the essential requirements for therapeutic use: high amplification capacity, ability to fuse with muscle fibers, renewal of the satellite cell population, dispersion in the whole body after vascular administration, persistence of long-term effect, and dramatic clinical improvement of treated animals. These preclinical results pave the way for a therapeutic trial in children with Duchenne muscular dystrophy.La dystrophie musculaire de Duchenne (DMD) est une maladie génétique progressive du muscle liée au chromosome X. Elle est la maladie génétique la plus fréquente chez l'homme. La thérapie cellulaire basée sur l'utilisation de cellules souches somatiques est une voie thérapeutique riche d'intérêt. Nous avons isolé, chez un modèle de chien myopathe, une cellule souche musculaire (MuStem) qui présente les qualités indispensables à une utilisation thérapeutique: forte capacité d'amplification, capacité à fusionner avec les fibres musculaires, renouvellement du contingent de cellules satellites, dispersion dans l'organisme après administration vasculaire, persistance de l'effet à long terme, spectaculaire amélioration clinique des animaux traités. Ces résultats précliniques ouvrent la voie à un essai thérapeutique chez l'enfant atteint de dystrophie musculaire de Duchenne

The skin is a significant but overlooked anatomical reservoir for vector-borne African trypanosomes

The role of mammalian skin in harbouring and transmitting arthropod-borne protozoan parasites has been overlooked for decades as these pathogens have been regarded primarily as blood-dwelling organisms. Intriguingly, infections with low or undetected blood parasites are common, particularly in the case of Human African Trypanosomiasis caused by Trypanosoma brucei gambiense. We hypothesise, therefore, the skin represents an anatomic reservoir of infection. Here we definitively show that substantial quantities of trypanosomes exist within the skin following experimental infection, which can be transmitted to the tsetse vector, even in the absence of detectable parasitaemia. Importantly, we demonstrate the presence of extravascular parasites in human skin biopsies from undiagnosed individuals. The identification of this novel reservoir requires a re-evaluation of current diagnostic methods and control policies. More broadly, our results indicate that transmission is a key evolutionary force driving parasite extravasation that could further result in tissue invasion-dependent pathology

Infection-mediated priming of phagocytes protects against lethal secondary Aspergillus fumigatus challenge

Phagocytes restrict the germination of Aspergillus fumigatus conidia and prevent the establishment of invasive pulmonary aspergillosis in immunecompetent mice. Here we report that immunecompetent mice recovering from a primary A. fumigatus challenge are protected against a secondary lethal challenge. Using RAGγc knock-out mice we show that this protection is independent of T, B and NK cells. In protected mice, lung phagocytes are recruited more rapidly and are more efficient in conidial phagocytosis and killing. Protection was also associated with an enhanced expression of CXCR2 and Dectin-1 on bone marrow phagocytes. We also show that protective lung cytokine and chemokine responses are induced more rapidly and with enhanced dynamics in protected mice. Our findings support the hypothesis that following a first encounter with a non-lethal dose of A. fumigatus conidia, the innate immune system is primed and can mediate protection against a secondary lethal infection

Liver-Resident Macrophage Necroptosis Orchestrates Type 1 Microbicidal Inflammation and Type-2-Mediated Tissue Repair during Bacterial Infection

International audienceKupffer 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

Fulminant Nocardiosis Due to a Multidrug-Resistant Isolate in a 12-Year-Old Immunocompetent Child

International audienceNocardiosis is a rare cause of infection that usually affects immunocompromised adult patients and might not be recognized by pediatricians. We report a fatal case of disseminated nocardiosis in a previously healthy child initially admitted for an abdominal mass with suspicion of a renal malignant tumor. The patient, originating from Mali without any medical history, displayed abdominal pain with progressive altered general status. Laboratory and imaging findings revealed lymphocytic meningitis and disseminated abscesses in the brain and the cerebellum and a large number of cystic lesions of the kidney. Despite being administered wide-spectrum antibiotics and antituberculous and antifungal therapies with an external ventricular drainage for intracranial hypertension, the patient died 6 days after his admission. Nocardia spp was cultured from a renal biopsy and the cerebrospinal fluid. Species identification and antibiotic susceptibility were obtained later, revealing a multidrug-resistant isolate of the Nocardia elegans/aobensis/africana complex. This case reveals the difficulties of diagnosing nocardiosis, in particular in children not known to be immunocompromised, because we face multiple differential diagnoses and the importance of treating nocardiosis appropriately because of intrinsic resistance issues

Encapsulated Bacillus anthracis interacts closely with liver endothelium.

International audienceBACKGROUND: The Bacillus anthracis poly-gamma-D-glutamate capsule is essential for virulence. It impedes phagocytosis and protects bacilli from the immune system, thus promoting systemic dissemination. METHODS: To further define the virulence mechanisms brought into play by the capsule, we characterized the interactions between encapsulated nontoxinogenic B. anthracis and its host in vivo through histological analysis, perfusion, and competition experiments with purified capsule. RESULTS: Clearance of encapsulated bacilli from the blood was rapid (>90% clearance within 5 min), with 75% of the bacteria being trapped in the liver. Competition experiments with purified capsule polyglutamate inhibited this interaction. At the septicemic phase of cutaneous infection with spores, the encapsulated bacilli were trapped in the vascular spaces of the liver and interacted closely with the liver endothelium in the sinusoids and terminal and portal veins. They often grow as microcolonies containing capsular material shed by the bacteria. CONCLUSION: We show that, in addition to its inhibitory effect on the interaction with the immune system, the capsule surrounding B. anthracis plays an active role in mediating the trapping of the bacteria within the liver and may thus contribute to anthrax pathogenesis. Because other microorganisms produce polyglutamate, it may also represent a general mechanism of virulence or in vivo survival

Multiparametric functional nuclear magnetic resonance imaging shows alterations associated with plasmid electrotransfer in mouse skeletal muscle.

BACKGROUND: In vivo gene electrotransfer is frequently used in preclinical gene therapy. Many studies have attempted to optimize protocols efficiency at the same time as reducing muscle damage. Most of them have reported histological evidence of muscle degeneration and completion of regeneration within 15 days. The functional consequences have rarely been addressed, which may reflect the lack of appropriate techniques. Yet, it is important to characterize the changes induced by the procedure itself because it may interfere with therapy. We used multiparametric functional (mpf)-nuclear magnetic resonance (NMR) imaging to evaluate mice hindlimb muscle after electrotransfer of an empty plasmid. METHODS: NMR experiments were performed in a 4T Bruker magnet. Arterial spin labeling imaging of perfusion and blood oxygenation level dependent contrast and (31) P spectroscopy of phosphocreatine kinetics and pH were simultaneously acquired from the mice hindlimb during 2 min of electrically stimulated exercise and recovery. RESULTS: After 15 days, hindlimb cross-sectional area decreased by 10% compared to control mice. Specific force-time integral and end-exercise pH were identical in both groups, whereas oxidative capacities increased. Perfusion values doubled, and oxygenation significantly decreased. Histology revealed: (i) degeneration/regeneration; (ii) a decrease in type IIb fibers and an increase in type I and IIa fibers; and (iii) increased capillary density. CONCLUSIONS: In this model, loss in muscle mass was accompanied by important alterations of perfusion and bioenergetics. Fifteen days after electrotransfer, this was correlated with fiber type shift, capillary bed remodeling and degeneration/regeneration. mpf-NMR provides new insights into the functional consequences of standard electrotransfer and represents a powerful tool for optimization and longitudinal assessment of preclinical gene therapy protocols

Protective or Deleterious Role of Scavenger Receptors SR-A and CD36 on Host Resistance to <i>Staphylococcus aureus</i> Depends on the Site of Infection

<div><p><i>Staphylococcus aureus</i> is a major human opportunistic pathogen responsible for a broad spectrum of infections ranging from benign skin infection to more severe life threatening disorders (e.g. pneumonia, sepsis), particularly in intensive care patients. Scavenger receptors (SR-A and CD36) are known to be involved in <i>S. aureus</i> recognition by immune cells in addition to MARCO, TLR2, NOD2 and α5β1 integrin. In the present study, we further deciphered the contribution of SR-A and CD36 scavenger receptors in the control of infection of mice by <i>S. aureus</i>. Using double SR-A/CD36 knockout mice (S/C-KO) and <i>S. aureus</i> strain HG001, a clinically relevant non-mutagenized strain, we showed that the absence of these two scavenger receptors was protective in peritoneal infection. In contrast, the deletion of these two receptors was detrimental in pulmonary infection following intranasal instillation. For pulmonary infection, susceptible mice (S/C-KO) had more colony-forming units (CFU) in their broncho-alveolar lavages fluids, associated with increased recruitment of macrophages and neutrophils. For peritoneal infection, susceptible mice (wild-type) had more CFU in their blood, but recruited less macrophages and neutrophils in the peritoneal cavity than resistant mice. Exacerbated cytokine levels were often observed in the susceptible mice in the infected compartment as well as in the plasma. The exception was the enhanced compartmentalized expression of IL-1β for the resistant mice (S/C-KO) after peritoneal infection. A similar mirrored susceptibility to <i>S. aureus</i> infection was also observed for MARCO and TLR2. <i>Marco and tlr2</i> -/- mice were more resistant to peritoneal infection but more susceptible to pulmonary infection than wild type mice. In conclusion, our results show that innate immune receptors can play distinct and opposite roles depending on the site of infection. Their presence is protective for local pulmonary infection, whereas it becomes detrimental in the peritoneal infection.</p></div