Exposure to Moulds in the Environment Triggers Allergic and Inflammatory Responses

Submitted by GAtherton on 6 June 2016

In the aftermath of flooding our homes and other buildings often become damp and consequently mouldy. More commonly we know that without adequate ventilation our homes can become damp as indoor air humidity rises and deposits its moisture on our walls and windows, especially when the walls are colder than the air and also as air temperature drops, forcing the water out of the air and onto surrounding surfaces.

Once mould grows it starts to produce spores and volatile chemicals and to release them into the air and this is thought to cause harm to human health – in particular when the spores of some mould species are inhaled deep into the lungs e.g. Aspergillus.

For the most part the illnesses caused were thought to be allergic, though recently evidence has accumulated sufficiently to also be sure that damp (and possibly moulds)  causes and exacerbates asthma.

This latest paper uses a mouse model for investigating the effects of  inhaled spores combined with a specifically designed machine that generates clouds of dry spores to detect the immunological responses to chronic exposure to low levels of dry Aspergillus spores, similar to that found in damp homes. They discovered that germination of spores of A. fumigatus was important  for the immune response and also that there were signs of both the allergic and inflammatory response pathways being activated via a novel mechanism involving IL-13.

The authors state “The results of this study suggest that personal exposure to low doses of fungal bioaerosols for long durations can result in the development of allergic responses involving moderate airway inflammation.”

When treating people who have been exposed to chronic low level exposure to fungal spores it might be important for doctors to treat both the allergic and inflammatory aspects of the illnesses caused rather than just assume that it is an allergic reaction.