title: Mycobacteria infect different cell types in the human lung and cause species dependent cellular changes in infected cells.
abstract: BACKGROUND
  Mycobacterial infections remain a significant cause of morbidity and mortality worldwide. Due to limitations of the currently available model systems, there are still comparably large gaps in the knowledge about the pathogenesis of these chronic inflammatory diseases in particular with regard to the human host. Therefore, we aimed to characterize the initial phase of mycobacterial infections utilizing a human ex vivo lung tissue culture model designated STST (Short-Term Stimulation of Tissues).
  
  
  METHODS
  Human lung tissues from 65 donors with a size of 0.5-1 cm(3) were infected each with two strains of three different mycobacterial species (M. tuberculosis, M. avium, and M. abscessus), respectively. In order to preserve both morphology and nucleic acids, the HOPE® fixation technique was used. The infected tissues were analyzed using histo- and molecular-pathological methods. Immunohistochemistry was applied to identify the infected cell types.
  
  
  RESULTS
  Morphologic comparisons between ex vivo incubated and non-incubated lung specimens revealed no noticeable differences. Viability of ex vivo stimulated tissues demonstrated by TUNEL-assay was acceptable. Serial sections verified sufficient diffusion of the infectious agents deep into the tissues. Infection was confirmed by Ziel Neelsen-staining and PCR to detect mycobacterial DNA. We observed the infection of different cell types, including macrophages, neutrophils, monocytes, and pneumocytes-II, which were critically dependent on the mycobacterial species used. Furthermore, different forms of nuclear alterations (karyopyknosis, karyorrhexis, karyolysis) resulting in cell death were detected in the infected cells, again with characteristic species-dependent differences.
  
  
  CONCLUSIONS
  We show the application of a human ex vivo tissue culture model for mycobacterial infections. The immediate primary infection of a set of different cell types and the characteristic morphologic changes observed in these infected human tissues significantly adds to the current understanding of the initial phase of human pulmonary tuberculosis. Further studies are ongoing to elucidate the molecular mechanisms involved in the early onset of mycobacterial infections in the human lung.
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. amirad_mon@yahoo.com.|Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia. amirad_mon@yahoo.com.
authors.forename: Dariimaa
authors.initials: D
authors.lastname: Ganbat
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. sseehase@fz-borstel.de.|Airway Research Center North (ARCN), Member of the German Center for Lung Research, Gießen, Germany. sseehase@fz-borstel.de.
authors.forename: Sophie
authors.initials: S
authors.lastname: Seehase
authors.affiliation: National Reference Center for Mycobacteria, Research Center Borstel, Borstel, Germany. elvira.richter@labor-limbach.de.|Present address: Labor Limbach, Heidelberg, Germany. elvira.richter@labor-limbach.de.
authors.forename: Elvira
authors.initials: E
authors.lastname: Richter
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. evollmer@fz-borstel.de.|Airway Research Center North (ARCN), Member of the German Center for Lung Research, Gießen, Germany. evollmer@fz-borstel.de.
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Vollmer
authors.affiliation: Microbial Interface Biology, Research Center Borstel, Borstel, Germany. nreiling@fz-borstel.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Reiling
authors.affiliation: Bioinformatics, Research Center Borstel, Borstel, Germany. kfellenberg@fz-borstel.de.
authors.forename: Kurt
authors.initials: K
authors.lastname: Fellenberg
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. kgaede@fz-borstel.de.|Airway Research Center North (ARCN), Member of the German Center for Lung Research, Gießen, Germany. kgaede@fz-borstel.de.
authors.forename: Karoline I
authors.initials: KI
authors.lastname: Gaede
authors.affiliation: Airway Research Center North (ARCN), Member of the German Center for Lung Research, Gießen, Germany. C.Kugler@lungenclinic.de.|Thoracic Surgery, Lungen Clinic Grosshansdorf, Grosshansdorf, Germany. C.Kugler@lungenclinic.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Kugler
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. tgoldmann@fz-borstel.de.|Airway Research Center North (ARCN), Member of the German Center for Lung Research, Gießen, Germany. tgoldmann@fz-borstel.de.
authors.forename: Torsten
authors.initials: T
authors.lastname: Goldmann
mesh_terms: D056809:Alveolar Epithelial Cells / Q000382:microbiology / Q000473:pathology; D002467:Cell Nucleus / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D008168:Lung / Q000378:metabolism / Q000473:pathology*; D008214:Lymphocytes / Q000382:microbiology / Q000473:pathology; D016676:Macrophages, Alveolar / Q000382:microbiology / Q000473:pathology; D009000:Monocytes / Q000382:microbiology / Q000473:pathology; D009161:Mycobacterium / Q000235:genetics; D009165:Mycobacterium Infections, Nontuberculous / Q000378:metabolism / Q000473:pathology*; D009162:Mycobacterium avium / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000235:genetics; D009504:Neutrophils / Q000382:microbiology / Q000473:pathology; D016133:Polymerase Chain Reaction; D046509:Tissue Culture Techniques; D014022:Tissue Survival; D014397:Tuberculosis, Pulmonary / Q000378:metabolism / Q000473:pathology*