Local delivery of GM-CSF protects mice from lethal pneumococcal pneumonia

K Steinwede, O Tempelhof, K Bolte, R Maus… - The Journal of …, 2011 - journals.aai.org
K Steinwede, O Tempelhof, K Bolte, R Maus, J Bohling, B Ueberberg, F Länger…
The Journal of Immunology, 2011journals.aai.org
The growth factor GM-CSF has an important role in pulmonary surfactant metabolism and
the regulation of antibacterial activities of lung sentinel cells. However, the potential of intra-
alveolar GM-CSF to augment lung protective immunity against inhaled bacterial pathogens
has not been defined in preclinical infection models. We hypothesized that transient
overexpression of GM-CSF in the lungs of mice by adenoviral gene transfer (Ad-GM-CSF)
would protect mice from subsequent lethal pneumococcal pneumonia. Our data show that …
Abstract
The growth factor GM-CSF has an important role in pulmonary surfactant metabolism and the regulation of antibacterial activities of lung sentinel cells. However, the potential of intra-alveolar GM-CSF to augment lung protective immunity against inhaled bacterial pathogens has not been defined in preclinical infection models. We hypothesized that transient overexpression of GM-CSF in the lungs of mice by adenoviral gene transfer (Ad-GM-CSF) would protect mice from subsequent lethal pneumococcal pneumonia. Our data show that intra-alveolar delivery of Ad-GM-CSF led to sustained increased pSTAT5 expression and PU. 1 protein expression in alveolar macrophages during a 28-d observation period. Pulmonary Ad-GM-CSF delivery 2–4 wk prior to infection of mice with Streptococcus pneumoniae significantly reduced mortality rates relative to control vector-treated mice. This increased survival was accompanied by increased inducible NO synthase expression, antibacterial activity, and a significant reduction in caspase-3–dependent apoptosis and secondary necrosis of lung sentinel cells. Importantly, therapeutic treatment of mice with rGM-CSF improved lung protective immunity and accelerated bacterial clearance after pneumococcal challenge. We conclude that prophylactic delivery of GM-CSF triggers long-lasting immunostimulatory effects in the lung in vivo and rescues mice from lethal pneumococcal pneumonia by improving antibacterial immunity. These data support use of novel antibiotic-independent immunostimulatory therapies to protect patients against bacterial pneumonias.
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