In vivo effect of adhesion inhibitor heparin on Legionella pneumophila pathogenesis in a murine pneumonia model.
OBJECTIVE
To examine the effect of intratracheal heparin instillation on Legionella pneumophila-related acute lung injury (ALI) and systemic dissemination.


METHODS
Prospective, controlled experimental study.


METHODS
University research laboratory.


METHODS
A/J mice received 5 microg of sulfated heparin intratracheally co-instilled with 10(6) or 10(8) colony-forming units (CFU) of a virulent isolate of L. pneumophila.


RESULTS
ALI was assessed in control groups (PBS and PBS-heparin) and on days 1, 2 and 3 post-infection, in terms of the lung wet-to-dry (W/D) weight ratios and of lung endothelial permeability to radio-labeled albumin (Perm-I(125)). Lung bacterial loads were measured and systemic spread was assessed by blood and target organ culture. The alveolar inflammatory response was evaluated by measuring the cytokine levels (TNF-alpha, IFN-gamma, IL-6 and IL-12p70) in bronchoalveolar lavage fluids (BALF). Co-instilled heparin improved mouse survival after the 10(8) CFU challenge (p < 0.01). On day 2, heparin co-instillation significantly reduced the W/D ratio and Perm-I(125) (p < 0.01 and p < 0.001 respectively), improved lung bacterial clearance (p < 0.001), prevented systemic dissemination (blood, liver, spleen, kidneys and brain cultures, all p < 0.05) and significantly increased IFN-gamma and IL-12p70 levels in BALF (p < 0.05).


CONCLUSIONS
Heparin co-instillation during intratracheal L. pneumophila challenge has a protective effect on the alveolar-capillary barrier and prevents bacterial dissemination. These results tend to confirm the competitive inhibition by heparin of L. pneumophila attachment to lung epithelium in vivo, and point to the possible involvement of a heparan-sulfate adhesin in L. pneumophila binding to pneumocytes.
Ader
Florence
F
Université Lyon 1, Centre National de référence des Légionelles, Faculté de Médecine Laennec, Lyon cedex 08, France. florence.ader@univ-lyon1.fr
Le Berre
Rozenn
R
Fackeure
Rémi
R
Raze
Dominique
D
Menozzi
Franco Dante
FD
Viget
Nathalie
N
Faure
Karine
K
Kipnis
Eric
E
Guery
Benoît
B
Jarraud
Sophie
S
Etienne
Jerome
J
Chidiac
Christian
C
D055371:Acute Lung Injury / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control*; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D016207:Cytokines / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D005343:Fibrinolytic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D006493:Heparin / Q000494:pharmacology / Q000627:therapeutic use*; D016952:Legionella pneumophila / Q000187:drug effects* / Q000472:pathogenicity; D007877:Legionnaires' Disease / Q000378:metabolism / Q000517:prevention & control*; D051379:Mice
D016207:Cytokines; D005343:Fibrinolytic Agents; D006493:Heparin