Director: Huerre Michel,René
The Histotechnology and Pathology Unit is part of the Microbial Pathogenesis Department, which studies bacterial infections (Mycobacteria, gram-positive, gram-negative), viral infections (Myxoma virus, HIV) and parasitic diseases (Entamoeba, Aspergillus) in animal models. Our unit also studies the mechanism of inflammation (Toll-like receptors) and the transcription factor involved (i.e. hnF1). We also use a Beta-imager for quantitative autoradiography on tissue or whole-body sections in several models of infectious diseases (experimental), to study the pharmacodistribution of neuroreceptors and to demonstrate the involvement of genes in development
I - Infectious diseases in human and experimental pathology
Mycobacteria (Coll. Unit of Mycobacteria, B. Gicquel, Unit of Bacterial Molecular Genetics: S. Cole, P. Brodin; Reference Centre for Mycobacteria: G. Marchal and Immune Regulation Unit: C. Leclerc & L. Majlessi). Mycobacteria are a large and ubiquitous group of pathogens that cause chronic inflammation. The histological spectrum is bipolar - granulomatous with activated macrophages containing a few pathogens, or histiocytic, containing numerous bacteria - according to the pathogenicity of the bacteria and the immune status of the host. Several experimental models have been used to study the lesions induced by several types of characterised mutant strain (metabolic strains, rd1 BCGetc.) in which pathogenicity is correlated with the in situ production of ESAT-6 protein. (Photo 1)
Neisseria (Coll. Unit of Neisseria, J.M. Alonso). Neisseria persist in the pharynx of the host and are able to invade the lung after the induction of local and general immunosuppression. This mechanism has been demonstrated in a murine model of pneumonia following influenza virus inoculation. Various mutant strains of Neisseria have been tested, and the results obtained suggest that host factors predominate in the pathogenesis of bacterial pneumonia.
Helicobacter (Coll. Unit of Mucosal Pathogenesis, A. Labigne, E. Touati and R. Ferrero). We have investigated the chronic gastric lesions induced by Helicobacter pylori (Hp) and mutagenic effects on the gastric epithelium in a transgenic mouse model (Big blue I lac z). The induction of mutagenic effects and local NO production were found to be correlated with the development and severity of gastritis and chronic metaplasia, considered precancerous lesions. The team of R. Ferrero has studied the role of the Nod1 system in inflammation and intraepithelial transduction.
Gram-positive bacteria. Listeria model. (Bacteria-Cell Interactions Unit) A series of cases of human placentitis has been studied in collaboration with Cochin Hospital (Prof. M.C. Vacher-Lavenu) and M. Lecuit has demonstrated the role of cadherin in a placental histoculture model.
Myxomavirus (F. Messud-Petit, C. Camus-Bouclainville, Veterinary School of Toulouse) NF-Kb is a key factor in development of the inflammatory reaction. Myxomavirus, responsible for myxomatosis in rabbits, encodes several proteins, including MNF (Myxoma Nuclear Factor). MNF has nine ankyrine repeats interacts with NF-Kb molecules and attenuates the inflammatory reaction. We have studied the lesions induced in the rabbit by mutant of myxomatosis virus deleted of MNF.
SIV and placenta infection. (E. Menu, F. Barre-Sinoussi, Retrovirus Unit) E. Menu has tested an original protocol involving the embedding of the placenta in a synthetic medium, making it possible to study local infection over time. Histological studies have demonstrated that architecture is preserved until day 10.
Parasites and fungi
Entamoeba histolytica. Liver amoebiasis. M.C. Rigothier and N. Guillen, Parasitology Unit. The kinetics of the inflammatory reaction and the role of mobility have been studied in the hamster model.
Aspergillosis (M. Chignard, V. Balloy, M. Si-Tahar; Pharmacology Unit and J.P. Latge, A. Beauvais, Aspergillosis Unit) Lung lesions have been characterised in various experimental models of invasive aspergillosis (Photo 2) . Vinblastin treatment induced severe, acute neutropenia and aspergillosis with numerous hyphae but no inflammatory reaction. Conversely, in corticosteroid-treated mice, lesions developed, with a diffuse, extensive inflammatory reaction, numerous polymorphonuclear cells and few hyphae. Several mutant strains have been studied and the role of TLR has been investigated.
II - . Phenotypic analysis of genetically modified strains.
2-1 HNF1 beta (coll L. Gresh, E, Fisher, Unité Génétique et maladies)
Hepatocyte Nuclear Factor 1beta (HNF1beta) is a homeoprotein predominantly expressed in renal, pancreatic and hepatic epithelia. We report that mice with renal-specific inactivation of HNF1beta develop polycystic kidney disease.
2-2 Plag1-/- (coll K. Hensen, C. Braem, W. Van de Wen, University of Leuven).
The pleomorphic adenoma gene 1 (Plag1) proto-oncogene encodes a transcription factor and is implicated in human tumorigenesis via ectopic overexpression. We establish that Plag1 disruption in mouse differentially affects pre- and postnatal growth and development of organs, with reproductive repercussions.
2-3 Model of vitiligo
We studied a transgenic model of vitiligo and melanoma in which ret oncogene fused to the metallothionein promoter. The occurrence of spontaneous tumor nodules in MT/ret mice with melanoma-associated vitiligo is significantly delayed when compared in melanoma mice without vitiligo. The results confirm that vitiligo is associated with clinical benefit and further demonstrate the crucial role of CD8+ T cells for tumor control in melanoma-associated vitiligo.
III - Quantitative autoradiography (Ana Cardona) The unit has developed several applications for quantitative autoradiography using the beta-imager, combined with pathological studies to demonstrate the topography of labelled molecules within tissues, or cells or whole bodies sections. These techniques made it possible to demonstrate that peptidoglycan from Helicobacter pylori strains was able to invade epithelial cells via NOD1(Coll. R. Ferrero and Agnès Labigne, Mucosal Pathogenesis Unit) The use of the beta imager allowed to study in a rat model the pharmacodistribution of sialorphin considered to be the first natural inhibitor of the NEP-encephalinase, caracterized in mammals (Collaboration C. Rougeot. Unité Pharmacologie des régulations neuro-endocrines) In addition, A. Bristeau-leprince has studied the pharmacocinetic of the DPTsh1(and cargo effect) in vivo in a mouse model (Collaboration Unité de Chimie Organique A. Garcia, A.Bristeau-Leprince C. Rougeot.)
Photo 1: demonstration of ESAT-6 in macrophages after BCG-rd1 infection.
Photo 2: Invasive aspergillosis in neutropenia.
Keywords: Infectious diseases, pathology, histopathology, pathogenesis, autoradiography