Evolution of foamy macrophages in the pulmonary granulomas of experimental tuberculosis models.
The chronic phase of Mycobacterium tuberculosis infection in mouse experimental models is characterized by the accumulation of foamy macrophages (FM)--which shape the outer ring of the granuloma - in the alveolar spaces, as detected in paraffin-embedded tissues stained with hematoxylin-eosin. In this study, the use of semi- and ultra-thin sections offers more detailed information about the origin of FM both in mouse and guinea-pig experimental models. Lipid bodies (LB) are present in macrophages from the beginning of infection and accumulate in the chronic phase. LB progress from an early (ELB) to a late (LLB) stage, defined according to their progressive capacity to generate cholesterol crystals, resembling atherosclerotic lesions. FM arise from massive accumulation of LLB. Electronic microscopy reveals intracellular lipophilic inclusions (ILIs) in those M. tuberculosis bacilli inside FM. It is our hypothesis that the accumulation of lipids in M. tuberculosis concomitant to the establishment of the non-replicating state prepares the bacilli for future reactivation and for facing future stressful environments.
Cáceres
Neus
N
Department of Microbiology, Fundació Institut per a la Investigació en Ciències de la Salut Germans Trias i Pujol, Badalona, Catalonia, Spain.
Tapia
Gustavo
G
Ojanguren
Isabel
I
Altare
Frederic
F
Gil
Olga
O
Pinto
Sergio
S
Vilaplana
Cristina
C
Cardona
Pere-Joan
PJ
D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D002908:Chronic Disease; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D005487:Foam Cells / Q000378:metabolism / Q000648:ultrastructure*; D006099:Granuloma / Q000378:metabolism / Q000473:pathology*; D006168:Guinea Pigs; D008168:Lung / Q000378:metabolism / Q000473:pathology; D016676:Macrophages, Alveolar / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008854:Microscopy, Electron; D009336:Necrosis / Q000378:metabolism / Q000473:pathology; D010588:Phagosomes / Q000648:ultrastructure; D014397:Tuberculosis, Pulmonary / Q000378:metabolism / Q000473:pathology*
D002784:Cholesterol