Infants with cystic fibrosis have altered fecal functional capacities with potential clinical and metabolic consequences

Persistent delay in maturation of the developing gut microbiota in infants with cystic fibrosis

The healthy human infant gut microbiome undergoes stereotypical changes in taxonomic composition between birth and maturation to an adult-like stable state. During this time, extensive communication between microbiota and the host immune system contributes to health status later in life. Although there are many reported associations between microbiota compositional alterations and disease in adults, less is known about how microbiome development is altered in pediatric diseases. One pediatric disease linked to altered gut microbiota composition is cystic fibrosis (CF), a multi-organ genetic disease involving impaired chloride secretion across epithelia and heightened inflammation both in the gut and at other body sites. Here, we use shotgun metagenomics to profile the strain-level composition and developmental dynamics of the infant fecal microbiota from several CF and non-CF longitudinal cohorts spanning from birth to greater than 36 months of life. We identify a set of keystone species that define microbiota development in early life in non-CF infants but are missing or decreased in relative abundance in infants with CF, resulting in a delayed pattern of microbiota maturation, persistent entrenchment in a transitional developmental phase, and subsequent failure to attain an adult-like stable microbiota. Delayed maturation is strongly associated with cumulative antibiotic treatments, and we also detect the increased relative abundance of oral-derived bacteria and higher levels of fungi in infants with CF, features that are associated with decreased gut bacterial density. These findings suggest the potential for future directed therapies targeted at overcoming developmental delays in microbiota maturation for infants with CF.IMPORTANCEThe human gastrointestinal tract harbors a diversity of microbes that colonize upon birth and collectively contribute to host health throughout life. Infants with the disease cystic fibrosis (CF) harbor altered gut microbiota compared to non-CF counterparts, with lower levels of beneficial bacteria. How this altered population is established in infants with CF and how it develops over the first years of life is not well understood. By leveraging multiple large non-CF infant fecal metagenomic data sets and samples from a CF cohort collected prior to highly effective modulator therapy, we define microbiome maturation in infants up to 3 years of age. Our findings identify conserved age-diagnostic species in the non-CF infant microbiome that are diminished in abundance in CF counterparts that instead exhibit an enrichment of oral-derived bacteria and fungi associated with antibiotic exposure. Together, our study builds toward microbiota-targeted therapy to restore healthy microbiota dynamics in infants with CF.

The Impact of Complementary Feeding on Fecal Microbiota in Exclusively Breast-Fed Infants with Cystic Fibrosis (A Descriptive Study)

BACKGROUND/OBJECTIVES

Early life gut microbiota plays a pivotal role in shaping immunity, metabolism, and overall health outcomes. This is relevant in healthy infants but may be even more crucial in infants with chronic devastating diseases, such as cystic fibrosis (CF). While the introduction of solid foods in healthy infants modifies the composition of colonic microbiota, less knowledge is available on those with CF. The aim of this descriptive observational study was to assess the composition of fecal microbiota in six exclusively breast-fed infants with CF, and then explore the changes induced upon the introduction of different foods.

METHODS

two types of fecal samples were collected from each subject: one during the exclusive-breastfeeding period, and the other after incorporating each new food in the ad libitum diet. The microbiota composition was analyzed by 16S rRNA amplicon sequencing.

RESULTS

Wide heterogenicity in the composition at the phylum level (variable proportions of Actinobacteriota, Proteobacteria, and Firmicutes, and the absence of Bacteroidota in all subjects) was found, and different enterotypes were characterized in each subject by the main presence of one genus: Bifidobacterium in Subject 1 (relative abundance of 54.4%), Klebsiella in Subject 3 (49.1%), Veillonella in Subjects 4 and 5 (32.7% and 36.9%, respectively), and Clostridium in Subject 6 (48.9%). The transition to complementary feeding induced variable changes in microbiota composition, suggesting a subject-specific response and highlighting the importance of inter-individual variation.

CONCLUSIONS

Further studies are required to identify which foods contribute to shaping colonic microbiota in the most favorable way for patients with CF using a personalized approach.

The impact of a whole foods dietary intervention on gastrointestinal symptoms, inflammation, and fecal microbiota in pediatric patients with cystic fibrosis: A pilot study

BACKGROUND

Gastrointestinal (GI) complications are a significant source of morbidity for people with cystic fibrosis (PwCF). Historically, dietary recommendations in CF have focused on calories, typically emphasizing a high fat diet. The changing landscape of CF highlights the need to update this nutritional strategy. There is little research into how the quality of calories consumed by PwCF influences nutritional outcomes, GI symptoms, or likely contributors: intestinal inflammation and GI microbiology. We assessed the feasibility of a whole foods-based diet (WFD) and avoidance of ultra-processed foods, measuring safety/tolerability, adherence, and GI symptoms, as well as fecal measures of inflammation and microbiota among children with CF (CwCF) with GI symptoms.

METHODS

Single center, 4-week dietary intervention involving CwCF aged 5-14 years who screened positive on GI symptom questionnaire. Assessments included weight, symptom questionnaires and adverse events (AEs). Stool was analyzed for microbiota (16S rRNA) and calprotectin.

RESULTS

108 children were pre-screened, 9 enrolled and 8 initiated and completed the study. There were no significant changes in weight and no AEs. PEDS-QL GI identified overall improvement in symptoms. Certain symptom domains (constipation, diarrhea, gas/bloating, stomach pain and hurt) demonstrated significant improvement on the WFD. Of two participants with abnormal fecal calprotectin at enrollment, both exhibited decreased values on WFD. There was no significant change in microbiota diversity.

CONCLUSION

A WFD diet was feasible and safe in CwCF. There was improvement in GI symptom scores based on both parent and child assessments. Larger studies are needed to further investigate effects on intestinal inflammation and microbiota.

Improving growth in infants with CF

Cystic fibrosis (CF) results in chronic pulmonary infections, inflammation, pancreatic insufficiency, and multiple gastrointestinal manifestations. Malnutrition and poor growth are hallmarks of CF, and strongly associated with poor outcomes. Through newborn screening, many infants can be diagnosed within a few days of life, which allows for early initiation of nutritional counseling and close clinical follow-up. Obstacles to growth for infants with CF start in utero, as newborns with CF can have a lower birth weight than the general population. Improving infant growth has been linked to improved clinical outcomes and survival. It remains a top priority and challenge for caregivers and healthcare teams. An interdisciplinary approach, including registered dietitian and social work support, is essential to optimize health for infants with CF. Remaining barriers to normalcy include deficits in linear growth, lack of accurate nutrition biomarkers, persistence of inequities related to social determinant of health, particularly in the global CF community.

The gastrointestinal microbiome, small bowel bacterial overgrowth, and microbiome modulators in cystic fibrosis

People with cystic fibrosis (pwCF) have an altered gastrointestinal microbiome. These individuals also demonstrate propensity toward developing small intestinal bacterial overgrowth (SIBO). The dysbiosis present has intestinal and extraintestinal implications, including potential links with the higher rates of gastrointestinal malignancies described in CF. Given these implications, there is growing interest in therapeutic options for microbiome modulation. Alternative therapies, including probiotics and prebiotics, and current CF transmembrane conductance regulator gene modulators are promising interventions for ameliorating gut microbiome dysfunction in pwCF. This article will characterize and discuss the current state of knowledge and expert opinions on gut dysbiosis and SIBO in the context of CF, before reviewing the current evidence supporting gut microbial modulating therapies in CF.

Changes in fecal lipidome after treatment with ivacaftor without changes in microbiome or bile acids

BACKGROUND

Alterations in gastrointestinal health are prominent manifestations of cystic fibrosis (CF) and can independently impact pulmonary function. Ivacaftor has been associated with robust improvements in pulmonary function and weight gain, but less is known about the impact of ivacaftor on the fecal microbiome, lipidome, and bile acids.

METHODS

Stool samples from 18 patients with CF and gating mutations (ages 6-61 years, 13 pancreatic insufficient) were analyzed for fecal microbiome and lipidome composition as well as bile acid concentrations at baseline and after 3 months of treatment with ivacaftor. Microbiome composition was also assessed in a healthy reference cohort.

RESULTS

Alpha and beta diversity of the microbiome were different between CF and reference cohort at baseline, but no treatment effect was seen in the CF cohort between baseline and 3 months. Seven lipids increased with treatment. No differences were seen in bile acid concentrations after treatment in CF. At baseline, 403 lipids and unconjugated bile acids were different between pancreatic insufficient (PI-CF) and sufficient (PS-CF) groups and 107 lipids were different between PI-CF and PS-CF after 3 months of treatment.

CONCLUSIONS

The composition and diversity of the fecal microbiome were different in CF as compared to a healthy reference, and did not change after 3 months of ivacaftor. We detected modest differences in the fecal lipidome with treatment. Differences in lipid and bile acid profiles between PS-CF and PI-CF were attenuated after 3 months of treatment.

Species- and subspecies-level characterization of health-associated bacterial consortia that colonize the human gut during infancy

BACKGROUND

The human gut microbiome develops rapidly during infancy, a key window of development coinciding with the maturation of the adaptive immune system. However, little is known about the microbiome growth dynamics over the first few months of life and whether there are any generalizable patterns across human populations. We performed metagenomic sequencing on stool samples (n = 94) from a cohort of infants (n = 15) at monthly intervals in the first 6 months of life, augmenting our dataset with seven published studies for a total of 4,441 metagenomes from 1,162 infants.

RESULTS

Strain-level de novo analysis was used to identify 592 of the most abundant organisms in the infant gut microbiome. Previously unrecognized consortia were identified which exhibited highly correlated abundances across samples and were composed of diverse species spanning multiple genera. Analysis of a published cohort of infants with cystic fibrosis identified one such novel consortium of diverse Enterobacterales which was positively correlated with weight gain. While all studies showed an increased community stability during the first year of life, microbial dynamics varied widely in the first few months of life, both by study and by individual.

CONCLUSION

By augmenting published metagenomic datasets with data from a newly established cohort, we were able to identify novel groups of organisms that are correlated with measures of robust human development. We hypothesize that the presence of these groups may impact human health in aggregate in ways that individual species may not in isolation.

Strain-level characterization of health-associated bacterial consortia that colonize the human gut during infancy

Background

The human gut microbiome develops rapidly during infancy, a key window of development coinciding with maturation of the adaptive immune system. However, little is known of the microbiome growth dynamics over the first few months of life and whether there are any generalizable patterns across human populations. We performed metagenomic sequencing on stool samples (n=94) from a cohort of infants (n=15) at monthly intervals in the first six months of life, augmenting our dataset with seven published studies for a total of 4,441 metagenomes from 1,162 infants.

Results

Strain-level de novo analysis was used to identify 592 of the most abundant organisms in the infant gut microbiome. Previously unrecognized consortia were identified which exhibited highly correlated abundances across samples and were composed of diverse species spanning multiple genera. Analysis of a cohort of infants with cystic fibrosis identified one such novel consortium of diverse Enterobacterales which was positively correlated with weight gain. While all studies showed an increased community stability during the first year of life, microbial dynamics varied widely in the first few months of life, both by study and by individual.

Conclusion

By augmenting published metagenomic datasets with data from a newly established cohort we were able to identify novel groups of organisms that are correlated with measures of robust human development. We hypothesize that the presence of these groups may impact human health in aggregate in ways that individual species may not in isolation.

Autoimmunity in people with cystic fibrosis

Cystic fibrosis (CF) clinicians may see patients who have difficult-to-manage symptoms that do not have a clear CF-related etiology, such as unusual gastrointestinal (GI) complaints, vasculitis, or arthritis. Alterations in immunity, inflammation and intraluminal dysbiosis create a milieu that may lead to autoimmunity, and the CF transmembrane regulator protein may have a direct role as well. While autoantibodies and other autoimmune markers may develop, these may or may not lead to organ involvement, therefore they are helpful but not sufficient to establish an autoimmune diagnosis. Autoimmune involvement of the GI tract is the best-established association. Next steps to understand autoimmunity in CF should include a more in-depth assessment of the community perspective on its impact. In addition, bringing together specialists in various fields including, but not limited to, pulmonology, gastroenterology, immunology, and rheumatology, would lead to cross-dissemination and help define the path forward in basic science and clinical practice.

Persistent delay in maturation of the developing gut microbiota in infants with cystic fibrosis

The healthy human infant gut microbiome undergoes stereotypical changes in taxonomic composition between birth and maturation to an adult-like stable state. During this time, extensive communication between microbiota and the host immune system contributes to health status later in life. Although there are many reported associations between microbiota compositional alterations and disease in adults, less is known about how microbiome development is altered in pediatric diseases. One pediatric disease linked to altered gut microbiota composition is cystic fibrosis (CF), a multi-organ genetic disease involving impaired chloride secretion across epithelia and heightened inflammation both in the gut and at other body sites. Here, we use shotgun metagenomics to profile the strain-level composition and developmental dynamics of the infant fecal microbiota from several CF and non-CF longitudinal cohorts spanning from birth to greater than 36 months of life. We identify a set of keystone species whose prevalence and abundance reproducibly define microbiota development in early life in non-CF infants, but are missing or decreased in relative abundance in infants with CF. The consequences of these CF-specific differences in gut microbiota composition and dynamics are a delayed pattern of microbiota maturation, persistent entrenchment in a transitional developmental phase, and subsequent failure to attain an adult-like stable microbiota. We also detect the increased relative abundance of oral-derived bacteria and higher levels of fungi in CF, features that are associated with decreased gut bacterial density in inflammatory bowel diseases. Our results define key differences in the gut microbiota during ontogeny in CF and suggest the potential for directed therapies to overcome developmental delays in microbiota maturation.

Can Bioactive Food Substances Contribute to Cystic Fibrosis-Related Cardiovascular Disease Prevention?

Advances in cystic fibrosis (CF) care have significantly improved the quality of life and life expectancy of patients. Nutritional therapy based on a high-calorie, high-fat diet, antibiotics, as well as new therapies focused on CFTR modulators change the natural course of the disease. They do so by improving pulmonary function and growing BMI. However, the increased weight of such patients can lead to unwanted long-term cardiovascular effects. People with CF (pwCF) experience several cardiovascular risk factors. Such factors include a high-fat diet and increased dietary intake, altered lipid metabolism, a decrease in the level of fat-soluble antioxidants, heightened systemic inflammation, therapeutic interventions, and diabetes mellitus. PwCF must pay special attention to food and eating habits in order to maintain a nutritional status that is as close as possible to the proper physiological one. They also have to benefit from appropriate nutritional counseling, which is essential in the evolution and prognosis of the disease. Growing evidence collected in the last years shows that many bioactive food components, such as phytochemicals, polyunsaturated fatty acids, and antioxidants have favorable effects in the management of CF. An important positive effect is cardiovascular prevention. The possibility of preventing/reducing cardiovascular risk in CF patients enhances both quality of life and life expectancy in the long run.

What Do We Know about the Microbiome in Cystic Fibrosis? Is There a Role for Probiotics and Prebiotics?

Cystic fibrosis (CF) is a life-shortening genetic disorder that affects the cystic fibrosis transmembrane conductance regulator (CFTR) protein. In the gastrointestinal (GI) tract, CFTR dysfunction results in low intestinal pH, thick and inspissated mucus, a lack of endogenous pancreatic enzymes, and reduced motility. These mechanisms, combined with antibiotic therapies, drive GI inflammation and significant alteration of the GI microbiota (dysbiosis). Dysbiosis and inflammation are key factors in systemic inflammation and GI complications including malignancy. The following review examines the potential for probiotic and prebiotic therapies to provide clinical benefits through modulation of the microbiome. Evidence from randomised control trials suggest probiotics are likely to improve GI inflammation and reduce the incidence of CF pulmonary exacerbations. However, the highly variable, low-quality data is a barrier to the implementation of probiotics into routine CF care. Epidemiological studies and clinical trials support the potential of dietary fibre and prebiotic supplements to beneficially modulate the microbiome in gastrointestinal conditions. To date, limited evidence is available on their safety and efficacy in CF. Variable responses to probiotics and prebiotics highlight the need for personalised approaches that consider an individual's underlying microbiota, diet, and existing medications against the backdrop of the complex nutritional needs in CF.