Researchers working on the ‘hygiene hypothesis’ have found more evidence that exposure to microbes may protect against the development of asthma, they report today.
A team led by Professor Fabrice Bureau at the University of Liege, Belgium, exposed large white blood cells called macrophages to DNA from bacteria, and found that this makes the cells strongly immunosuppressive by "strongly amplifying a population of interstitial macrophages."
This effect persisted for several months in laboratory mice, and the adapted cells were then able to prevent and treat asthma in tests on these mice, the scientists confirm.
Details are published today (22 March) in Immunity. The team explain that previous studies suggest that exposure to a so-called "non-hygienic" environment, rich in microbes, plays a protective role against the development of allergies, including asthma.
They believe their discovery could aid the development of a cell therapy based on the administration of these regulatory macrophages to people with asthma. Although synthetic compounds mimicking bacterial DNA have undergone human trials for asthma, none of these compounds are currently approved for use, partly due to a lack of knowledge about their mechanisms of action.
Professor Bureau says: "If it is possible to create suppressive macrophage from blood monocytes of asthmatic patients, it is quite conceivable to reinject these macrophages into the lungs of these same patients, during routine bronchoscopy procedures performed by pneumologists here at the University of Liege, and to evaluate the therapeutic potential of these cells."
The team have already a patent for exclusive use of their invention, and are going to begin studies with human participants soon.
Sabatel, C. et al. Bacterial CpG-DNA protects against asthma by expanding lung interstitial regulatory macrophages from local and splenic reservoir monocytes. Immunity 22 March 2017
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