Sydney, March 18 Iron build-up in the lung cells and tissues is associated with worse asthma symptoms and lower lung function, say researchers.
The study, published in the European Respiratory Journal, included data from asthma patient samples and mouse models, and showed a relationship between iron build-up in the lung cells and tissues and the severity of asthma.
Experimental models also showed that iron build-up in the lungs triggers immune system responses that are typical in asthma and lead to worsening of the disease.
This includes effects like increased mucus secretion and scarring of the lungs, which result in narrowing of the airways and making breathing difficult.
"We showed that lung function was lowest among patients with the highest levels of iron build-up in their airway cells and tissues," said study lead author Jay Horvat, Associate Professor at the University of Newcastle in Australia.
"As lower iron levels outside of cells and higher iron levels within cells were both associated with worse lung function, we think that the immune system's role in 'hiding' iron minerals within the lung cells may be contributing to asthma severity," Horvat added.
For the findings, the researchers used a combination of asthma patient samples and experimental models to investigate irregular iron absorption into lung cells and to assess how lung cell iron levels affect disease severity.
First, the researchers assessed airway cell iron levels in 11 severe and 12 mild-to-moderate asthma patients and compared their iron levels with 12 healthy people who did not have asthma.
Asthma severity was determined by how much air a person could breathe out in one second and based on the frequency of experiencing asthma symptoms.
The researchers collected airway cell samples from participants using biopsy.
They also conducted multiple tests to asses iron levels in the airway cell samples and found that iron levels outside of the lung cells were lower in asthma patients compared with healthy people; iron levels were also significantly lower in severe asthmatics compared with mild-to-moderate asthmatics.
In contrast, iron levels within the lung cells were markedly higher in the bronchoscope 'wash' samples of mild-to-moderate and severe asthmatics compared with healthy people.
The difference in lung cell iron levels between severe asthmatics compared with mild-to-moderate asthmatics was not significant, but the analyses showed that having high levels of iron in the lung cells and less iron outside of cells was associated with more severe airflow obstruction.
Taken together, the results show that lower iron levels outside of cells and higher iron levels within cells were both associated with lower lung function and worse asthma.
Next, the researchers carried out lab tests using two different mouse models to investigate the effects of increasing lung cell iron levels on asthma severity.
In one of the experimental models conducted over an eight-week period, one group of mice was exposed to iron overload through diet and another group were fed a normal low-iron diet.
After eight weeks, liver and lung tissues were collected from the mice for further analysis and airway inflammation was measured.
In a separate genetic model, the researchers triggered iron overloading in the lung cells of mice that were fed a normal iron diet, to assess the effects on the lungs.
The analyses showed that increasing the lung cell iron levels caused inflammatory cell responses such as increased mucus secretion and scarring in the airways, which the researchers say leads to worsening of asthma.
( With inputs from IANS )