Pathogenesis of Aspergillus fumigatus and the kinetics of galactomannan in an in vitro model of early invasive pulmonary aspergillosis: implications for antifungal therapy.
BACKGROUND
Little is known about the pathogenesis of invasive pulmonary aspergillosis and the relationship between the kinetics of diagnostic markers and the outcome of antifungal therapy.


METHODS
An in vitro model of the human alveolus, consisting of a bilayer of human alveolar epithelial and endothelial cells, was developed. An Aspergillus fumigatus strain expressing green fluorescent protein was used. Invasion of the cell bilayer was studied using confocal and electron microscopy. The kinetics of culture, polymerase chain reaction, and galactomannan were determined. Galactomannan was used to measure the antifungal effect of macrophages and amphotericin B. A mathematical model was developed, and results were bridged to humans.


RESULTS
A. fumigatus penetrated the cellular bilayer 14-16 h after inoculation. Galactomannan levels were inextricably tied to fungal invasion and were a robust measure of the antifungal effect of macrophages and amphotericin B. Neither amphotericin nor macrophages alone was able to suppress the growth of A. fumigatus; rather, the combination was required. Monte Carlo simulations showed that human dosages of amphotericin B of at least 0.6 mg/kg were required to achieve adequate drug exposure.


CONCLUSIONS
This model provides a strategy by which relationships among pathogenesis, immunological effectors, and antifungal drug therapy for invasive pulmonary aspergillosis may be further understood.
Hope
William W
WW
Immunocompromised Host Section, Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Kruhlak
Michael J
MJ
Lyman
Caron A
CA
Petraitiene
Ruta
R
Petraitis
Vidmantas
V
Francesconi
Andrea
A
Kasai
Miki
M
Mickiene
Diana
D
Sein
Tin
T
Peter
Joanne
J
Kelaher
Amy M
AM
Hughes
Johanna E
JE
Cotton
Margaret P
MP
Cotten
Catherine J
CJ
Bacher
John
J
Tripathi
Sanjay
S
Bermudez
Louis
L
Maugel
Timothy K
TK
Zerfas
Patricia M
PM
Wingard
John R
JR
Drusano
George L
GL
Walsh
Thomas J
TJ
D000666:Amphotericin B / Q000493:pharmacokinetics* / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001158:Arteries; D001228:Aspergillosis / Q000382:microbiology* / Q000628:therapy*; D001232:Aspergillus fumigatus / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000382:microbiology; D005690:Galactose / Q000031:analogs & derivatives; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008168:Lung / Q000098:blood supply; D008172:Lung Diseases, Fungal / Q000382:microbiology*; D008264:Macrophages; D008351:Mannans / Q000737:chemistry*; D008954:Models, Biological; D009010:Monte Carlo Method
D000935:Antifungal Agents; D008351:Mannans; C012990:galactomannan; D000666:Amphotericin B; D005690:Galactose