Irish researchers have made a major breakthrough in understanding why women with the life-threatening disease cystic fibrosis (CF) have a poorer survival rate than men, it emerged today.
Academics found higher levels of the hormone oestrogen limits the lungs’ ability to fight infection and bacteria that attack good cells.
CF is a life-threatening inherited disease which targets the lungs and the digestive system.
A build-up of mucus can make it difficult to clear bacteria and leads to cycles of lung infections and inflammation, which can eventually damage a patient’s lungs.
Ireland has both the highest incidence of CF in the world – at 2.98 per 10,000 - and the highest carrier rate in the world with 1 in 19 individuals classed as carriers.
The incidence of cystic fibrosis in Ireland is almost four times the average rate in other EU countries and the USA.
Researchers from the Royal College of Surgeons in Ireland (RCSI) and Dublin’s Beaumont Hospital studied why female CF patients have poorer survival rates, poorer lung function and are more susceptible to lung infections than male CF patients.
They found oestrogen limits the lungs’ ability to respond to infection and revealed it prevented the release of a chemical signal (IL-8) that triggers the influx of white blood cells (neutrophils) into the lungs to fight the infection when cells are attacked by bacteria.
The study was published in the American Journal of Respiratory and Critical Care Medicine.
Dr Sanjay Chotirmall, joint lead author of the paper, said: “Our ultimate aim would be improving the quality of life and survival rate for female sufferers of cystic fibrosis.”
Medics revealed that in most people’s lungs, a protective layer of fluid known as the airway surface liquid (ASL) keeps the lungs’ lining hydrated and defends the lungs from infections.
However in CF sufferers this layer is thinner and previous research demonstrated that this protective layer is reduced even further at times of elevated levels of oestrogen during the menstrual cycle, so the likelihood of acquiring an infection is increased during this period.
Dr Chotirmall, of the Respiratory Research Division of RCSI, Beaumont Hospital, said: “This reduced response to infection combined with a greater likelihood of acquiring an infection in the first place, both caused by high oestrogen levels, goes a long way towards explaining how females with cystic fibrosis have more aggressive disease, particularly with the onset of puberty.
“Our research may contribute towards narrowing the gender gap in cystic fibrosis by identifying new potential targets for treatment, such as stabilisation of oestrogen levels, or more aggressively employing preventative strategies against infection during the one week of the four-week menstrual cycle where oestrogen levels are at their highest.”