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Obesity-related gut damage may worsen asthma symptoms


Southampton researchers have found an association between gut damage due to weight gain and more severe asthma.


The researchers showed increased body weight was associated with worse control of asthma. They also found it led to greater inflammation and gut permeability. This means more water, bacteria and toxins can leak through the gut walls.


These results suggest losing weight could improve symptoms for patients with severe asthma. They also identify the gut as a new target for asthma treatments for patients with obesity.


Dr Hans Michael Haitchi and Dr Ramesh Kurukulaaratchy were involved in the study. They are both researchers at the NIHR Southampton Biomedical Research Centre. Both are also Associate Professors in Respiratory Medicine at the University of Southampton.


Gut permeability and asthma


The researchers examined the relationship between body weight and gut permeability in patients with severe asthma. They looked at the symptoms and body weight of 98 patients from the Wessex asthma cohort of difficult asthma (WATCH) study in Southampton.


The participants had a body mass index (BMI) ranging from lean to obese. They reported their symptoms using a questionnaire on asthma control. The research team also took blood samples. They used these to measure levels of markers for gut permeability and asthma-related inflammation.


Patients with poorly controlled asthma had significantly higher levels of gut permeability. These levels increased with increasing body weight. More gut permeability markers also correlated with more asthma-related inflammatory markers.


Dr Haitchi said: “Asthma is a chronic inflammatory condition which we know can be worse in patients with obesity. Although it is common, if poorly controlled asthma can lead to serious complications and an increased risk of severe asthma attacks, which can be life threatening.


“These findings give a good indication that improving patient’s diet and their gut environment could be an effective way of managing their asthma.”


Collaborative research


The study was a collaboration with researchers at Nottingham Trent University. These included Dr Neil Williams and lead investigator Cristina Parenti.


It included only a small number of patients with difficult-to-treat and severe asthma. Further studies could study participants with well-controlled asthma, over a range of BMIs. They also examine whether targeting the gut improves patients' asthma control.


Cristina Parenti said: “Our initial findings show that increased gut permeability is likely to be a factor in worsening asthma symptoms in patients with obesity. So it will be interesting to look at whether dietary interventions can improve symptoms for these patients.”