A recent study published in Gut Microbes identified correlations between dietary habits, gastrointestinal and respiratory microbiota, lung function, and pulmonary exacerbations in children with cystic fibrosis (CF).

For the purpose of this prospective, cross-sectional, controlled observational study, the researchers recruited 82 participants at an Australian tertiary pediatric hospital. They compared a cohort of children with CF to a cohort of healthy controls from April 2018 to September 2019.

The participants were asked to provide stool and airway (sputum or oropharyngeal swab) samples and complete a clinical questionnaire and a 120-item semiquantitative food frequency questionnaire. For patients with CF, a detailed medical chart review was also conducted.

The samples were analyzed by DNA extraction and 16S ribosomal RNA gene sequencing. Enzyme-linked immunosorbent assay (ELISA) testing was used to measure levels of calprotectin, a biomarker of gastrointestinal inflammation.

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According to the results, children with CF had significant respiratory and gastrointestinal dysbiosis as well as increased intestinal inflammation when compared to age- and sex-matched healthy controls. In addition, they demonstrated reduced relative intakes of whole grains, fiber, and resistant starch alongside increased relative intakes of total, saturated, and trans fats.

The researchers also identified significant and multidirectional associations between diet, gastrointestinal microbiota, respiratory microbiota, and clinically relevant endpoints.

They found the calprotectin levels to correlate positively with the consumption of takeaway and noncore foods and negatively with the intake of grains, whole grains, and core foods.

Akkermansia, one of the key bacterial genera that were reduced in the stool of children with CF, negatively correlated with calprotectin levels and positively correlated with the percentage predicted forced expiratory volume over 1 second (FEV1%).

Moreover, the number of recent pulmonary exacerbations was negatively correlated with the presence of butyrate-producing gastrointestinal bacteria and positively correlated with the airway bacterium Stenotrophomonas maltophilia.

“Our findings position the CF diet as a potential modulator in gastrointestinal inflammation and the proposed gut-lung axial relationship in CF,” the authors wrote. “The dietary intake of whole grains, fiber, and resistant starch may be protective against intestinal inflammation and should be explored as potential therapeutic adjuvants for children with CF.”

Respiratory and gastrointestinal dysbiosis along with gastrointestinal inflammation represent distinct hallmarks of CF. Although the microbial “gut-lung axis” is well-researched in chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease, scarce evidence connects these events in CF.

Reference

McKay I, van Dorst J, Katz T, et al. Diet and the gut-lung axis in cystic fibrosis – direct & indirect links. Gut Microbes. Published online December 27, 2022. doi:10.1080/19490976.2022.2156254