Is adipose tissue a place for Mycobacterium tuberculosis persistence?
BACKGROUND
Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), has the ability to persist in its human host for exceptionally long periods of time. However, little is known about the location of the bacilli in latently infected individuals. Long-term mycobacterial persistence in the lungs has been reported, but this may not sufficiently account for strictly extra-pulmonary TB, which represents 10-15% of the reactivation cases.


RESULTS
We applied in situ and conventional PCR to sections of adipose tissue samples of various anatomical origins from 19 individuals from Mexico and 20 from France who had died from causes other than TB. M. tuberculosis DNA could be detected by either or both techniques in fat tissue surrounding the kidneys, the stomach, the lymph nodes, the heart and the skin in 9/57 Mexican samples (6/19 individuals), and in 8/26 French samples (6/20 individuals). In addition, mycobacteria could be immuno-detected in perinodal adipose tissue of 1 out of 3 biopsy samples from individuals with active TB. In vitro, using a combination of adipose cell models, including the widely used murine adipose cell line 3T3-L1, as well as primary human adipocytes, we show that after binding to scavenger receptors, M. tuberculosis can enter within adipocytes, where it accumulates intracytoplasmic lipid inclusions and survives in a non-replicating state that is insensitive to the major anti-mycobacterial drug isoniazid.


CONCLUSIONS
Given the abundance and the wide distribution of the adipose tissue throughout the body, our results suggest that this tissue, among others, might constitute a vast reservoir where the tubercle bacillus could persist for long periods of time, and avoid both killing by antimicrobials and recognition by the host immune system. In addition, M. tuberculosis-infected adipocytes might provide a new model to investigate dormancy and to evaluate new drugs for the treatment of persistent infection.
Neyrolles
Olivier
O
Genetics and Biochemistry of Microorganisms, Centre National de la Recherche Scientifique, Paris, France. neyrolle@pasteur.fr
Hernández-Pando
Rogelio
R
Pietri-Rouxel
France
F
Fornès
Paul
P
Tailleux
Ludovic
L
Barrios Payán
Jorge Alberto
JA
Pivert
Elisabeth
E
Bordat
Yann
Y
Aguilar
Diane
D
Prévost
Marie-Christine
MC
Petit
Caroline
C
Gicquel
Brigitte
B
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000382:microbiology / Q000648:ultrastructure; D000273:Adipose Tissue / Q000382:microbiology*; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D054884:Host-Pathogen Interactions / Q000276:immunology; D006801:Humans; D055985:Latent Tuberculosis / Q000276:immunology / Q000382:microbiology*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity*; D051116:Receptors, Scavenger / Q000502:physiology; D014376:Tuberculosis / Q000382:microbiology
D017931:DNA Primers; D004269:DNA, Bacterial; D051116:Receptors, Scavenger