Obesity-related gut damage may worsen asthma symptoms

Changes in gut function caused by weight gain are associated with an increase in asthma severity, according to research involving Faculty of Medicine researchers.

The study, which was a collaboration with Neil Williams, Senior Lecturer in Exercise Physiology and Nutrition, at Nottingham Trent University, showed a significant association of increasing body weight with higher levels of inflammation, signs of gut permeability (where water, bacteria and toxins can leak through), and poorer control of asthma. These findings, which were presented at the Society for Endocrinology annual conference, suggest that losing weight could improve symptoms for patients with severe asthma and highlights the gut as a potential, alternative therapeutic target for improving asthma control in patients with obesity.

In the study, researchers examined the relationship between body weight and gut permeability with the symptoms of 98 patients with severe asthma from the Wessex AsThma CoHort of difficult asthma (WATCH) study at Southampton. Patients with lean to obese body mass index (BMI) reported their symptoms using the Asthma Control Questionnaire-6. Blood tests were taken to measure levels of gutpermeability markers, as well as markers of asthma-related inflammation. Patients with poorly controlled asthma had significantly higher levels of gut permeability and these levels increased with increasing body weight. Increasing concentrations of gut permeability markers also correlated with higher levels of asthma-related inflammatory markers.

Hans Michael Haitchi and Ramesh Kurukulaaratchy, both Associate Professors in Respiratory Medicine at the University of Southampton were involved in the study. 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.”

The study included only a small number of patients with difficult-to-treat and severe asthma. More research is needed to study the effects in participants with well-controlled asthma, over a range of BMIs, as well as examining whether targeting the gut can improve asthma control in affected patients. Lead investigator, Cristina Parenti, from Nottingham Trent University, concluded: “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.”