title: Histopathological findings, phenotyping of inflammatory cells, and expression of markers of nitritative injury in joint tissue samples from calves after vaccination and intraarticular challenge with Mycoplasma bovis strain 1067.
abstract: BACKGROUND
  The pathogenesis of caseonecrotic lesions developing in lungs and joints of calves infected with Mycoplasma bovis is not clear and attempts to prevent M. bovis-induced disease by vaccines have been largely unsuccessful. In this investigation, joint samples from 4 calves, i.e. 2 vaccinated and 2 non-vaccinated, of a vaccination experiment with intraarticular challenge were examined. The aim was to characterize the histopathological findings, the phenotypes of inflammatory cells, the expression of class II major histocompatibility complex (MHC class II) molecules, and the expression of markers for nitritative stress, i.e. inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT), in synovial membrane samples from these calves. Furthermore, the samples were examined for M. bovis antigens including variable surface protein (Vsp) antigens and M. bovis organisms by cultivation techniques.
  
  
  RESULTS
  The inoculated joints of all 4 calves had caseonecrotic and inflammatory lesions. Necrotic foci were demarcated by phagocytic cells, i.e. macrophages and neutrophilic granulocytes, and by T and B lymphocytes. The presence of M. bovis antigens in necrotic tissue lesions was associated with expression of iNOS and NT by macrophages. Only single macrophages demarcating the necrotic foci were positive for MHC class II. Microbiological results revealed that M. bovis had spread to approximately 27% of the non-inoculated joints. Differences in extent or severity between the lesions in samples from vaccinated and non-vaccinated animals were not seen.
  
  
  CONCLUSIONS
  The results suggest that nitritative injury, as in pneumonic lung tissue of M. bovis-infected calves, is involved in the development of caseonecrotic joint lesions. Only single macrophages were positive for MHC class II indicating down-regulation of antigen-presenting mechanisms possibly caused by local production of iNOS and NO by infiltrating macrophages.
authors.forename: Vemuri Rama
authors.initials: VR
authors.lastname: Devi
authors.forename: François
authors.initials: F
authors.lastname: Poumarat
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Grand
authors.forename: Renate
authors.initials: R
authors.lastname: Rosengarten
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hermeyer
authors.affiliation: Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, Hannover, D-30559, Germany. marion.hewicker-trautwein@tiho-hannover.de.
authors.forename: Marion
authors.initials: M
authors.lastname: Hewicker-Trautwein
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000378:metabolism; D000942:Antigens, Bacterial / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000382:microbiology / Q000473:pathology*; D016207:Cytokines / Q000097:blood; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007150:Immunohistochemistry / Q000662:veterinary; D007596:Joints / Q000382:microbiology*; D009175:Mycoplasma Infections / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D045682:Mycoplasma bovis / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D013583:Synovial Membrane / Q000382:microbiology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014611:Vaccination / Q000662:veterinary
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D015415:Biomarkers; D016207:Cytokines; D000949:Histocompatibility Antigens Class II; C121437:Vsp protein, bacterial; C002744:3-nitrotyrosine; D014443:Tyrosine; D052247:Nitric Oxide Synthase Type II