Gastrointestinal complications of cystic fibrosis

Functional variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are associated with increased risk of colorectal cancer

BACKGROUND

Individuals with cystic fibrosis (CF; a recessive disorder) have an increased risk of colorectal cancer (CRC). Evidence suggests individuals with a single CFTR variant may also have increased CRC risk.

METHODS

Using population-based studies (GECCO, CORECT, CCFR, and ARIC; 53 785 CRC cases and 58 010 controls), we tested for an association between the most common CFTR variant (Phe508del) and CRC risk. For replication, we used whole exome sequencing data from UK Biobank (UKB; 5126 cases and 20 504 controls matched 4:1 based on genetic distance, age, and sex), and extended our analyses to all other heterozygous CFTR variants annotated as CF-causing.

RESULTS

In our meta-analysis of GECCO-CORECT-CCFR-ARIC, the odds ratio (OR) for CRC risk associated with Phe508del was 1.11 (P = 0.010). In our UKB replication, the OR for CRC risk associated with Phe508del was 1.28 (P = 0.002). The sequencing data from UKB also revealed an association between the presence of any other single CF-causing variant (excluding Phe508del) and CRC risk (OR = 1.33; P = 0.030). When stratifying CFTR variants by functional class, class I variants (no protein produced) had a stronger association (OR = 1.77; p = 0.002), while class II variants (misfolding and retention of the protein in the endoplasmic reticulum) other than Phe508del (OR = 1.75; p = 0.107) had similar effect size as Phe508del, and variants in classes III-VI had non-significant ORs less than 1.0 and/or were not present in cases.

CONCLUSIONS

CF-causing heterozygous variants, especially class I variants, are associated with a modest but statistically significant increased CRC risk. More research is needed to explain the biology underlying these associations.

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.

Impact of acid blocker therapy on growth, gut microbiome, and lung disease in young children with cystic fibrosis

OBJECTIVE

Acid blocker therapy (ABT) has become common in cystic fibrosis (CF), despite insufficient evidence for benefits and studies showing potentially negative effects. We examined associations between ABT usage and growth, gut microbiome (GM), and early-onset lung disease in young children with CF.

METHODS

One hundred and forty-five infants with CF born during 2012-2017, diagnosed through newborn screening by age 3 months and followed to 36 months of age at six CF centers were evaluated. Longitudinal data on growth, pancreatic functional status, pulmonary symptoms, and acid blocker medications were prospectively collected. Early-onset lung disease severity was evaluated by a clinical scoring system. GM composition was assessed by 16S rRNA methodology.

RESULTS

ABT use before age 3 years was frequent, with 81 (56%) of patients on H2 receptor antagonist (H2RA) or proton pump inhibitor (PPI), and higher among pancreatic insufficient (60%) versus pancreatic sufficient (26%) children. H2RA was commonly prescribed in infancy before transitioning to PPI. Growth improvements were not significantly greater, while GM α-diversity at 3 years of age was significantly lower and early-onset lung disease more severe, in persistent ABT users compared to nonusers of ABT.

CONCLUSION

In our cohort of young children with CF, early and persistent ABT use was not associated with significant growth benefits and instead showed associations with reduced GM diversity and negative effects on early-onset lung disease. Consequentially, there is a critical need for systematic evaluation and comprehensive risk-benefit analysis of ABT to ensure proper guidelines for children 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.

Identification of 6,9-dihydro-5H-pyrrolo[3,2-h]quinazolines as a new class of F508del-CFTR correctors for the treatment of cystic fibrosis

Although substantial advances have been obtained in the pharmacological treatment of cystic fibrosis (CF) with the approval of Kaftrio, a combination of two correctors (VX-661, VX-445) and one potentiator (VX-770), new modulators are still needed to rescue F508del and other CFTR mutants with trafficking defects. We have previously identified PP compounds based on a tricyclic core as correctors with high efficacy in the rescue of F508del-CFTR on native epithelial cells of CF patients, particularly in combination with class 1 correctors (VX-809, VX-661). Compound PP028 was found as a lead candidate for the high rescue of F508del-CFTR and used for mechanistic insight indicating that PP028 behaves as a class 3 corrector, similarly to VX-445. From the exploration of the chemical space around the hit structure, based on iterative cycles of chemical synthesis and functional testing, the class of 6,9-dihydro-5H-pyrrolo [3,2-h]quinazolines with corrector activity was discovered. Within a series of 38 analogues, two derivatives emerged as promising candidates and used for further insight to assess the mechanism of action. Both compounds, decorated with a benzensulfonylamino group at the pyrimidine moiety, were able to generate a dose-dependent increase in CFTR function, particularly in the presence of VX-809. Half-effective concentrations (EC50) were in the single digit micromolar range and decreased in the presence of VX-809 thus indicating a synergistic interaction with class 1 correctors. Synergy was also observed with corr-4a (class 2 corrector) but not with VX-445 and PP028 (class 3 correctors) indicating that the new compounds behave as class 3 correctors. These results suggest that tricyclic pyrrolo-quinazolines interact with CFTR at a site different from that of VX-809 and represent a novel class of CFTR correctors suitable for combinatorial pharmacological treatments for the basic defect in CF.

Increased activity of epithelial Cdc42 Rho GTPase and tight junction permeability in the Cftr knockout intestine

Increased intestinal permeability is a manifestation of cystic fibrosis (CF) in people with CF (pwCF) and in CF mouse models. CF transmembrane conductance regulator knockout (Cftr KO) mouse intestine exhibits increased proliferation and Wnt/β-catenin signaling relative to wild-type mice (WT). Since the Rho GTPase Cdc42 plays a central role in intestinal epithelial proliferation and tight junction remodeling, we hypothesized that Cdc42 may be altered in the Cftr KO crypts. Immunofluorescence showed distinct tight junction localization of Cdc42 in Cftr KO fresh crypts and enteroids, the latter indicating an epithelial-autonomous feature. Quantitative PCR and immunoblots revealed similar expression of Cdc42 in the Cftr KO crypts/enteroids relative to WT, whereas pulldown assays showed increased GTP-bound (active) Cdc42 in proportion to total Cdc42 in Cftr KO enteroids. Cdc42 activity in the Cftr KO and WT enteroids could be reduced by inhibition of the Wnt transducer Disheveled. With the use of a dye permeability assay, Cftr KO enteroids exhibited increased paracellular permeability to 3 kDa dextran relative to WT. Leak permeability and Cdc42 tight junction localization were reduced to a greater extent by inhibition of Wnt/β-catenin signaling with endo-IWR1 in Cftr KO relative to WT enteroids. Increased proliferation or inhibition of Cdc42 activity with ML141 in WT enteroids had no effect on permeability. In contrast, inhibition of Cdc42 with ML141 increased permeability to both 3 kDa dextran and tight junction impermeant 500 kDa dextran in Cftr KO enteroids. These data suggest that increased constitutive Cdc42 activity may alter the stability of paracellular permeability in Cftr KO crypt epithelium.NEW & NOTEWORTHY Increased tight junction localization and GTP-bound activity of the Rho GTPase Cdc42 was identified in small intestinal crypts and enteroids of cystic fibrosis (CF) transmembrane conductance regulator knockout (Cftr KO) mice. The increase in epithelial Cdc42 activity was associated with increased Wnt signaling. Paracellular flux of an uncharged solute (3 kDa dextran) in Cftr KO enteroids indicated a moderate leak permeability under basal conditions that was strongly exacerbated by Cdc42 inhibition. These findings suggest increased activity of Cdc42 in the Cftr KO intestine underlies alterations in intestinal permeability.

Case Series: Hyperbilirubinemia under elexacaftor/tezacaftor/ivacaftor in the presence of Gilbert's syndrome

Liver-related side effects are a known complication of treatment with elexacaftor/tezacaftor/ivacaftor (ETI) for cystic fibrosis (CF). Gilbert's syndrome is caused by a genetic mutation that reduces activity of the enzyme UDP glucuronosyltransferase 1 polypeptide A1 (UGT1A1), causing elevated levels of unconjugated bilirubin in the blood and duodenal bile. The presence of Gilbert's syndrome and CF might represent additive risk factors for liver-related adverse events during ETI treatment. This case series describes six people with CF (pwCF) in whom previously unknown Gilbert's syndrome was unmasked after initiation of treatment with ETI. Although all patients had some level of hepatic dysfunction and/or elevated levels of bilirubin after initiation of ETI, the clinical course varied. Only one patient had to stop ETI therapy altogether, while the others were able to continue treatment (some at a reduced dosage and others at the full recommended daily dosage). All patients, even those using a lower dosage, experienced clinical benefit during ETI therapy. Gilbert's syndrome is not a contraindication for ETI therapy but may be mistaken for a risk factor for liver-related adverse events in pwCF. This is something that physicians need to be aware of in pwCF who show liver adverse events during ETI therapy.

Diagnosis, Management, and Prognosis of Cystic Fibrosis-Related Liver Disease in Children

Cystic fibrosis (CF) is a multifaceted disorder predominantly investigated for its pulmonary manifestations, yet patients with CF also exhibit a spectrum of extrapulmonary manifestations, notably those involving the hepatobiliary system. The latter constitutes the third leading cause of morbidity and mortality in individuals with CF. Cystic fibrosis-related liver disease (CFLD), with an escalating prevalence, manifests diverse clinical presentations ranging from hepatomegaly to cirrhosis and hepatopulmonary syndrome. Consequently, early detection and appropriate management are imperative for sustaining the health and influencing the quality of life of CF patients afflicted with CFLD. This review aims to consolidate existing knowledge by providing a comprehensive overview of hepatobiliary manifestations associated with CF. It delineates the clinical hepatobiliary manifestations, diagnostic methodologies, incorporating minimally invasive markers, and therapeutic approaches, encompassing the impact of novel CFTR modulators on CFLD. Given the exigency of early diagnosis and the intricate management of CFLD, a multidisciplinary team approach is essential to optimize care and enhance the quality of life for this subset of patients. In conclusion, recognizing CF as more than solely a pulmonary ailment, the authors underscore the imperative for further clinical investigations to establish a more robust evidence base for CFLD management within the continuum of this chronic disease.

Diagnosis and Management of Gastrointestinal Manifestations in Children with Cystic Fibrosis

Cystic fibrosis (CF) is primarily known for its pulmonary consequences, which are extensively explored in the existing literature. However, it is noteworthy that individuals with CF commonly display gastrointestinal (G-I) manifestations due to the substantial presence of the cystic fibrosis transmembrane conductance regulator (CFTR) protein in the intestinal tract. Recognized as pivotal nonpulmonary aspects of CF, G-I manifestations exhibit a diverse spectrum. Identifying and effectively managing these manifestations are crucial for sustaining health and influencing the overall quality of life for CF patients. This review aims to synthesize existing knowledge, providing a comprehensive overview of the G-I manifestations associated with CF. Each specific G-I manifestation, along with the diagnostic methodologies and therapeutic approaches, is delineated, encompassing the impact of innovative treatments targeting the fundamental effects of CF on the G-I tract. The findings underscore the imperative for prompt diagnosis and meticulous management of G-I manifestations, necessitating a multidisciplinary team approach for optimal care and enhancement of the quality of life for affected individuals. In conclusion, the authors emphasize the urgency for further clinical studies to establish a more robust evidence base for managing G-I symptoms within the context of this chronic disease. Such endeavors are deemed essential for advancing understanding and refining the clinical care of CF patients with G-I manifestations.

Cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic disease caused by variants in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR dysfunction results in abnormal chloride and bicarbonate transport in epithelial cells, leading to a multiorgan disease dominated by respiratory and digestive manifestations. The respiratory disease, which is characterized by airway mucus plugging, chronic bacterial infection and progressive development of bronchiectasis, may lead to chronic respiratory failure, which is the main cause of premature death in people with CF. Over the past 50 years, major progress has been obtained by implementing multidisciplinary care, including nutritional support, airway clearance techniques and antibiotics in specialized CF centers. The past 10 years have further seen the progressive development of oral medications, called CFTR modulators, that partially restore ion transport and lead to a major improvement in clinical manifestations and lung function, presumably resulting in longer survival. Although an increasing proportion of people with CF are being treated with CFTR modulators, challenges remain regarding access to CFTR modulators due to their high cost, and their lack of marketing approval and/or effectiveness in people with rare CFTR variants. The anticipated increase in the number of adults with CF and their aging also challenge the current organization of CF care. The purpose of this review article is to describe current status and future perspective of CF disease and care.

The Impact of Long-Term Macrolide Exposure on the Gut Microbiome and Its Implications for Metabolic Control

Long-term low-dose macrolide therapy is now widely used in the treatment of chronic respiratory diseases for its immune-modulating effects, although the antimicrobial properties of macrolides can also have collateral impacts on the gut microbiome. We investigated whether such treatment altered intestinal commensal microbiology and whether any such changes affected systemic immune and metabolic regulation. In healthy adults exposed to 4 weeks of low-dose erythromycin or azithromycin, as used clinically, we observed consistent shifts in gut microbiome composition, with a reduction in microbial capacity related to carbohydrate metabolism and short-chain fatty acid biosynthesis. These changes were accompanied by alterations in systemic biomarkers relating to immune (interleukin 5 [IL-5], IL-10, monocyte chemoattractant protein 1 [MCP-1]) and metabolic (serotonin [5-HT], C-peptide) homeostasis. Transplantation of erythromycin-exposed murine microbiota into germ-free mice demonstrated that changes in metabolic homeostasis and gastrointestinal motility, but not systemic immune regulation, resulted from changes in intestinal microbiology caused by macrolide treatment. Our findings highlight the potential for long-term low-dose macrolide therapy to influence host physiology via alteration of the gut microbiome. IMPORTANCE Long-term macrolide therapy is widely used in chronic respiratory diseases although its antibacterial activity can also affect the gut microbiota, a key regulator of host physiology. Macrolide-associated studies on the gut microbiota have been limited to short antibiotic courses and have not examined its consequences for host immune and metabolic regulation. This study revealed that long-term macrolides depleted keystone bacteria and impacted host regulation, mediated directly by macrolide activity or indirectly by alterations to the gut microbiota. Understanding these macrolide-associated mechanisms will contribute to identifying the risk of long-term exposure and highlights the importance of targeted therapy for maintenance of the gut microbiota.

Novel tricyclic pyrrolo-quinolines as pharmacological correctors of the mutant CFTR chloride channel

F508del, the most frequent mutation in cystic fibrosis (CF), impairs the stability and folding of the CFTR chloride channel, thus resulting in intracellular retention and CFTR degradation. The F508del defect can be targeted with pharmacological correctors, such as VX-809 and VX-445, that stabilize CFTR and improve its trafficking to plasma membrane. Using a functional test to evaluate a panel of chemical compounds, we have identified tricyclic pyrrolo-quinolines as novel F508del correctors with high efficacy on primary airway epithelial cells from CF patients. The most effective compound, PP028, showed synergy when combined with VX-809 and VX-661 but not with VX-445. By testing the ability of correctors to stabilize CFTR fragments of different length, we found that VX-809 is effective on the amino-terminal portion of the protein that includes the first membrane-spanning domain (amino acids 1-387). Instead, PP028 and VX-445 only show a stabilizing effect when the second membrane-spanning domain is included (amino acids 1-1181). Our results indicate that tricyclic pyrrolo-quinolines are a novel class of CFTR correctors that, similarly to VX-445, interact with CFTR at a site different from that of VX-809. Tricyclic pirrolo-quinolines may represent novel CFTR correctors suitable for combinatorial pharmacological treatments to treat the basic defect in CF.

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.

Cystic fibrosis and primary ciliary dyskinesia: Similarities and differences

Cystic fibrosis (CF) and Primary ciliary dyskinesia (PCD) are both rare chronic diseases, inherited disorders associated with multiple complications, namely respiratory complications, due to impaired mucociliary clearance that affect severely patients' lives. Although both are classified as rare diseases, PCD has a much lower prevalence than CF, particularly among Caucasians. As a result, CF is well studied, better recognized by clinicians, and with some therapeutic approaches already available. Whereas PCD is still largely unknown, and thus the approach is based on consensus guidelines, expert opinion, and extrapolation from the larger evidence base available for patients with CF. Both diseases have some clinical similarities but are very different, necessitating different treatment by specialists who are familiar with the complexities of each disease.This review aims to provide an overview of the knowledge about the two diseases with a focus on the similarities and differences between both in terms of disease mechanisms, common clinical manifestations, genetics and the most relevant therapeutic options. We hoped to raise clinical awareness about PCD, what it is, how it differs from CF, and how much information is still lacking. Furthermore, this review emphasises the fact that both diseases require ongoing research to find better treatments and, in particular for PCD, to fill the medical and scientific gaps.

Elexacaftor/tezacaftor/ivacaftor and gastrointestinal outcomes in cystic fibrosis: Report of promise-GI

BACKGROUND

Elexacaftor/tezacaftor/ivacaftor (ETI) improves pulmonary disease in people with cystic fibrosis (PwCF), but its effect on gastrointestinal symptoms, which also affect quality of life, is not clear.

METHODS

PROMISE is a 56-center prospective, observational study of ETI in PwCF >12 years and at least one F508del allele. Gastrointestinal symptoms, evaluated by validated questionnaires: Patient Assessment of Upper Gastrointestinal Disorders-Symptom (PAGI-SYM), Patient Assessment of Constipation-Symptom (PAC-SYM), Patient Assessment of Constipation-Quality of Life (PAC-QOL)), fecal calprotectin, steatocrit and elastase-1 were measured before and 6 months after ETI initiation. Mean difference and 95% confidence intervals were obtained from linear regression with adjustment for age and sex.

RESULTS

438 participants fully completed at least 1 questionnaire. Mean (SD) for baseline PAGI-SYM, PAC-SYM, and PAC-QOL total scores were 0.56 (0.59), 0.47 (0.45), and 0.69 (0.53) out of maximum 5, 4, and 5, respectively (higher score indicates greater severity). Corresponding age- and sex-adjusted 6 months mean changes (95% CI) in total scores were -0.15 (-0.21, -0.09) for PAGI-SYM, -0.14 (-0.19, -0.09) for PAC-SYM, and -0.15 (-0.21, -0.10) for PAC-QOL. While statistically significant, changes were small and unlikely to be of clinical importance. Fecal calprotectin showed a change (95% CI) from baseline of -66.2 µg/g (-86.1, -46.2) at 6 months, while fecal elastase and steatocrit did not meaningfully change.

CONCLUSIONS

After 6 months of ETI, fecal markers of inflammation decreased. Gastrointestinal symptoms improved, but the effect size was small. Pancreatic insufficiency did not improve.

Lower Expression of CFTR Is Associated with Higher Mortality in a Meta-Analysis of Individuals with Colorectal Cancer

Individuals with cystic fibrosis (CF), caused by biallelic germline mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), have higher risk and earlier onset of colorectal cancer (CRC). A subset of CRC patients in the non-CF population expresses low levels of tumoral CFTR mRNA which may also cause decreased CFTR activity. To determine the consequences of reduced CFTR expression in this population, we investigated association of tumoral CFTR expression with overall and disease-specific mortality in CRC patients. CFTR mRNA expression, clinical factors and survival data from 1177 CRC patients reported in the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus studies GSE39582 and GSE17538 were included. Log-transformed and z-normalized [mean = 0, standard deviation (SD) = 1] CFTR expression values were modeled as quartiles or dichotomized at the median. Univariate and multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for overall and disease-specific mortality in individual studies and meta-analyses. Analyses of each of the three individual datasets showed a robust association of decreased CFTR expression with increased mortality. In meta-analyses adjusted for stage at diagnosis, age and sex, CFTR expression was inversely associated with risk of overall death [pooled HR (95% CI): 0.70 (0.57-0.86)] and disease-specific death [pooled HR (95% CI): 0.68 (0.47-0.99)]. Associations did not differ by stage at diagnosis, age, or sex. Meta-analysis of overall death stratified by microsatellite instable (MSI) versus microsatellite stable (MSS) status indicated potential interaction between MSI/MSS status and CFTR expression, (p-interaction: 0.06). The findings from these three datasets support the hypothesis that low CFTR expression is associated with increased CRC mortality.

Nutritional Care in Children with Cystic Fibrosis

Patients with cystic fibrosis (CF) are prone to malnutrition and growth failure, mostly due to malabsorption caused by the derangement in the chloride transport across epithelial surfaces. Thus, optimal nutritional care and support should be an integral part of the management of the disease, with the aim of ameliorating clinical outcomes and life expectancy. In this report, we analyzed the nutrition support across the different ages, in patients with CF, with a focus on the relationships with growth, nutritional status, disease outcomes and the use of the CF transmembrane conductance regulator (CFTR) modulators. The nutrition support goal in CF care should begin as early as possible after diagnosis and include the achievement of an optimal nutritional status to support the growth stages and puberty development in children, that will further support the maintenance of an optimal nutritional status in adult life. The cornerstone of nutrition in patients with CF is a high calorie, high-fat diet, in conjunction with a better control of malabsorption due to pancreatic enzyme replacement therapy, and attention to the adequate supplementation of fat-soluble vitamins. When the oral caloric intake is not enough for reaching the anthropometric nutritional goals, supplemental enteral feeding should be initiated to improve growth and the nutritional status. In the last decade, the therapeutic possibilities towards CF have grown in a consistent way. The positive effects of CFTR modulators on nutritional status mainly consist in the improvement in weight gain and BMI, both in children and adults, and in an amelioration in terms of the pulmonary function and reduction of exacerbations. Several challenges need to be overcome with the development of new drugs, to transform CF from a fatal disease to a treatable chronic disease with specialized multidisciplinary care.

Cystic Fibrosis-Related Gut Dysbiosis: A Systematic Review

BACKGROUND AND AIMS

Cystic Fibrosis (CF) is associated with gut dysbiosis, local and systemic inflammation, and impaired immune function. Gut microbiota dysbiosis results from changes in the complex gut milieu in response to CF transmembrane conductance regulator (CFTR) dysfunction, pancreatic malabsorption, diet, medications, and environmental influences. In several diseases, alteration of the gut microbiota influences local and systemic inflammation and disease outcomes. We conducted a systematic review of the gut microbiota in CF and explored factors influencing dysbiosis.

METHODS

An electronic search of three databases was conducted in January 2019, and re-run in June 2021. Human, animal, and in vitro studies were included. The primary outcome was differences in the gut microbiota between people with CF (pwCF) and healthy controls. Secondary outcomes included the relationship between the gut microbiota and other factors, including diet, medication, inflammation, and pulmonary function in pwCF.

RESULTS

Thirty-eight studies were identified. The literature confirmed the presence of CF-related gut dysbiosis, characterized by reduced diversity and several taxonomic changes. There was a relative increase of bacteria associated with a pro-inflammatory response coupled with a reduction of those considered anti-inflammatory. However, studies linking gut dysbiosis to systemic and lung inflammation were limited. Causes of gut dysbiosis were multifactorial, and findings were variable. Data on the impact of CFTR modulators on the gut microbiota were limited.

CONCLUSIONS

CF-related gut dysbiosis is evident in pwCF. Whether this influences local and systemic disease and is amenable to interventions with diet and drugs, such as CFTR modulators, requires further investigation.

The association of fecal calprotectin and respiratory exacerbation in cystic fibrosis patients

Background

CF patients experience several episodes of pulmonary exacerbations and reduction in their lung function progressively. Lung function is not the only diagnostic index by physicians to decide if CF patients require antibiotic therapy following pulmonary exacerbations. Non-invasive fecal indicators are increasingly being used to assess intestinal inflammation. Calprotectin is the most extensively utilized fecal biomarker in recent CF researches.

Methods

In this longitudinal study, 30 CF patients (1–18 years) without current infectious gastroenteritis were recruited from Mofid Children's Hospital and Masih Daneshvari Hospital, Tehran, Iran. Then, fecal calprotectin levels were evaluated before treatment, two weeks after systemic antibiotic administration, as well as recurrence of pulmonary exacerbation after first post-hospital discharge.

Results

The initial fecal calprotectin level in CF patients receiving antibiotics was 651.13 ± 671.04, significantly decreasing two weeks after antibiotic therapy and following recurrence (171.81 ± 224.40, 607.93 ± 549.89, respectively; P < 0.01). Following systemic antibiotic treatment, the patient's respiratory and GI symptoms improved (P < 0.01).

Conclusion

Our findings revealed that fecal calprotectin modifications are associated with CF pulmonary exacerbations and antibiotic treatment could reduce calprotectin levels. Therefore, the fecal calprotectin level could be considered as a diagnostic tool and an index to follow the response to treatment in CF pulmonary exacerbations.

Surgical considerations in cystic fibrosis: what every general surgeon needs to know

Cystic fibrosis (CF) is a complex multiorgan disease, which often affects the gastrointestinal tract. With improved CF specific therapies and multidisciplinary management, patients with CF are now living longer with a median life expectancy of around 50 years. This increased life expectancy has resulted in corresponding increase in presentations of the CF patient with comorbid surgical conditions that were never important considerations. Investigations and management of these conditions, such as distal intestinal obstruction syndrome and colorectal cancer warrant good clinical understanding of the unique challenges that CF patients present including chronic immunosuppression, impaired respiratory function and their multi-organ dysfunction. The purpose of this review is to provide general surgeons with a contemporary update on the CF related surgical issues as they are likely to become increasingly involved in the care of these complex patients and form an integral part of the multidisciplinary team.

Pharmacogenomics: a tool to improve medication safety and efficacy in patients with cystic fibrosis

Cystic fibrosis is a genetic, multiorgan system disease that involves the use of many medications to control symptoms associated with the underlying condition. Many of these medications have Clinical Pharmacogenetics Implementation Consortium evidence-based guidelines for pharmacogenomics that are available to guide dosing. The aim of this article is to review relevant literature and evaluate the utility of preemptive pharmacogenomics testing for persons with cystic fibrosis and propose a pharmacogenomics panel that could be considered standard of care for persons with cystic fibrosis.

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.

The Intestinal Microbiome and Cystic Fibrosis Transmembrane Conductance Regulator Modulators: Emerging Themes in the Management of Gastrointestinal Manifestations of Cystic Fibrosis

PURPOSE OF REVIEW

While commonly associated with pulmonary manifestations, cystic fibrosis (CF) is a systemic disease with wide-ranging effects on the gastrointestinal (GI) tract. This article reviews major recent updates in gastroenterological CF care and research.

RECENT FINDINGS

The high burden of GI symptoms in CF has led to recent studies assessing GI-specific symptom questionnaires and scoring systems. Intestinal dysbiosis potentially contributes to gastrointestinal symptoms in patients with CF and an increased risk of gastrointestinal cancers in CF. An increased incidence of colorectal cancer (CRC) has led to CF-specific CRC screening and surveillance recommendations. Pharmacologic therapies targeting specific cystic fibrosis transmembrane conductance regulator (CFTR) mutations have shown promise in treating GI manifestations of CF. New research has highlighted the importance of intestinal dysbiosis in CF. Future studies should assess whether CFTR modulators affect the gut microbiome and whether altering the gut microbiome will impact GI symptoms and GI cancer risk.

Surveillance of Colorectal Cancer (CRC) in Cystic Fibrosis (CF) Patients

Cystic Fibrosis (CF) is the commonest inherited genetic disorder in Caucasians due to a mutation in the gene CFTR (Cystic Fibrosis Transmembrane Conductance Regulator), and it should be considered as an Inherited Colorectal Cancer (CRC) Syndrome. In the United States, physicians of CF Foundation established the “Developing Innovative Gastroenterology Speciality Training Program” to increase the research on CF in gastrointestinal and hepatobiliary diseases. The risk to develop a CRC is 5–10 times higher in CF patients than in the general population and even greater in CF patients receiving immunosuppressive therapy due to organ transplantation (30-fold increased risk relative to the general population). Colonoscopy should be considered the best screening for CRC in CF patients. The screening colonoscopy should be started at the age of 40 in CF patients and, if negative, a new colonoscopy should be performed every 5 years and every 3 years if adenomas are detected. For transplanted CF patients, the screening colonoscopy could be started at the age of 35, in transplanted patients at the age of 30 and, if before, at the age of 30. CF transplanted patients, between the age of 35 and 55, must repeat colonoscopy every 3 years. Our review draws attention towards the clinically relevant development of CRC in CF patients, and it may pave the way for further screenings and studies.

Evaluation of Fused Pyrrolothiazole Systems as Correctors of Mutant CFTR Protein

Cystic fibrosis (CF) is a genetic disease caused by mutations that impair the function of the CFTR chloride channel. The most frequent mutation, F508del, causes misfolding and premature degradation of CFTR protein. This defect can be overcome with pharmacological agents named “correctors”. So far, at least three different classes of correctors have been identified based on the additive/synergistic effects that are obtained when compounds of different classes are combined together. The development of class 2 correctors has lagged behind that of compounds belonging to the other classes. It was shown that the efficacy of the prototypical class 2 corrector, the bithiazole corr-4a, could be improved by generating conformationally-locked bithiazoles. In the present study, we investigated the effect of tricyclic pyrrolothiazoles as analogues of constrained bithiazoles. Thirty-five compounds were tested using the functional assay based on the halide-sensitive yellow fluorescent protein (HS-YFP) that measured CFTR activity. One compound, having a six atom carbocyle central ring in the tricyclic pyrrolothiazole system and bearing a pivalamide group at the thiazole moiety and a 5-chloro-2-methoxyphenyl carboxamide at the pyrrole ring, significantly increased F508del-CFTR activity. This compound could lead to the synthesis of a novel class of CFTR correctors.

A multicentre analysis of Clostridium difficile in persons with Cystic Fibrosis demonstrates that carriage may be transient and highly variable with respect to strain and level

PURPOSE

Clostridium difficile has been reported to occur in the gastrointestinal tract of 50% of Cystic Fibrosis (CF) subjects, however, clinical C. difficile infection (CDI) is a rare occurrence in this cohort despite the presence of toxigenic and hypervirulent ribotypes. Here, we present the first longitudinal, multicentre analysis of C. difficile prevalence among adult CF subjects.

METHODOLOGY

Faecal samples were collected from adults with CF (selected based on confirmed Pseudomonas aeruginosa pulmonary colonisation) from Ireland, UK and Belgium as part of the CFMATTERS clinical research trial (grant No. 603038) and from non-CF controls. Faecal samples were collected on enrolment, at three monthly intervals, during pulmonary exacerbation and three months post exacerbation. C. difficile was isolated from faecal samples by ethanol shocking followed by culturing on cycloserine cefoxitin egg yolk agar. Isolates were characterised in terms of ribotype, toxin type and antibiotic susceptibility to antibiotics routinely used in the treatment of CDI (metronidazole and vancomycin) and those implicated in induction of CDI (ciprofloxacin and moxifloxacin).

RESULTS

Prevalence of C. difficile among CF subjects in the three sites was similar ranging from 47% to 50% at baseline, while the healthy control cohort had a carriage rate of 7.1%. Including subjects who were positive for C. difficile at any time point there was a higher carriage rate of 71.4%, 66.7% and 63.2% in Ireland, UK, and Belgium, respectively. Ribotyping of 80 isolates from 45 CF persons, over multiple time points revealed 23 distinct ribotypes with two ribotypes (046 and 078) shared by all centres. The proportion of toxigenic isolates varied across the sites, ranging from 66.7% in Ireland to 52.9% in Belgium and 100% in the UK. Antibiotic susceptibility rates to vancomycin, metronidazole, ciprofloxacin and moxifloxacin was 100%, 97.5%, 1.3% and 63.8%, respectively.

CONCLUSIONS

This study demonstrates the highest carriage rate of C. difficile to date in a CF cohort. Longitudinal data show that C. difficile can be a transient inhabitant of the CF gut, changing both in terms of strain and excretion rates.

Decreased Wait Time and Increased Satisfaction With Bedside Pancreatic Enzyme Dosing for the Inpatient Adolescent With Cystic Fibrosis: A Quality Improvement Project Comparing Enzyme Self-Administration to Nurse Administration

For children with cystic fibrosis (CF), enzymes are essential with meals to absorb nutrients and ensure adequate growth. When hospitalized, CF patients typically rely on nurse-administered medications. Recently, a pediatric hospital unit began allowing adolescents with CF enzymes at the bedside. Postimplementation, a satisfaction questionnaire was administered to participating patients and nurses measuring patient and nurse satisfaction with access to bedside enzymes versus nurse administration and overall time for enzyme delivery. The survey utilized a 5-point Likert scale. The wait time for pancreatic enzymes decreased for self-administered enzymes when compared to those that were nurse administered. All (11/11) patients and 86% (12/14) of nurses preferred the self-administration of enzymes. Hospitalized pediatric CF patients and nurses had higher levels of satisfaction with enzyme self-administration. Immediate access to enzymes in room safes impact patient autonomy, reflecting home self-care practices. Decreases in wait times optimize nutritional growth and healing while hospitalized. As a result, a new limited scope policy allowing patient-administered enzymes is now in place in the pediatric inpatient CF unit.

Changes in fecal microbiota with CFTR modulator therapy: A pilot study

Studies have demonstrated that people with CF with pancreatic insufficiency (PI) have fecal dysbioses. Evidence suggests the causes of these dysbioses are multifactorial, and that important drivers include antibiotic exposure, dietary intake, and CF gastrointestinal tract dysfunction, including nutrient malabsorption. In this pilot study, we tested whether initiation of the CFTR modulator treatments ivacaftor (in a cohort of pancreatic sufficient (PS) people with CF and an R117H CFTR variant) or lumacaftor/ivacaftor (in a cohort of PI people with CF and an F508del variant) changed fecal measures of malabsorption or fecal microbiomes. While we identified no statistically significant fecal changes with either treatment, we detected trends in the PI cohort when initiating lumacaftor/ivacaftor towards decreased fecal fat content and towards fecal microbiomes that more closely resembled the fecal microbiota of people without PI. While these findings support a model in which nutrient malabsorption resulting from CF-induced PI drives fecal dysbiosis, they must be validated in future, larger studies of fecal microbiome and malabsorption outcomes with highly effective CFTR modulator therapies.

Increased Fecal Calprotectin Is Associated with Worse Gastrointestinal Symptoms and Quality of Life Scores in Children with Cystic Fibrosis

In cystic fibrosis (CF), cystic fibrosis transmembrane regulator (CFTR) dysfunction leads to digestive disorders that promote intestinal inflammation and dysbiosis enhancing gastrointestinal symptoms. In pancreatic insufficiency CF patients, both intestinal inflammation and dysbiosis, are associated with an increase in the fecal calprotectin (FC) level. However, associations between the FC level, gastrointestinal symptoms, and quality of life (QoL) remain poorly studied. We aimed to assess such associations in pancreatic insufficiency CF children. The FC level was measured in pancreatic insufficiency CF children's stool samples. Children and their parents completed two questionnaires: The Gastrointestinal Symptoms Scales 3.0-PedsQLTM and the Quality of Life Pediatric Inventory 4.0-PedsQLTM. Lower scores indicated worse symptomatology or QoL. Thirty-seven CF children were included. A FC level above 250 µg/g was associated with worse gastrointestinal symptoms and QoL scores. The FC level was inversely correlated with several gastrointestinal scores assessed by children (i.e., Total, "Heart Burn Reflux", "Nausea and Vomiting", and "Gas and Bloating"). Several QoL scores were correlated with gastrointestinal scores. The FC level was weakly associated with clinical parameters. Some gastrointestinal and QoL scores were related to disease severity associated parameters. In CF, the FC level, biomarker previously related to intestinal inflammation and dysbiosis, was associated with worse digestive symptoms and QoL scores.

Dysregulated signalling pathways in innate immune cells with cystic fibrosis mutations

Cystic fibrosis (CF) is one of the most common life-limiting recessive genetic disorders in Caucasians, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). CF is a multi-organ disease that involves the lungs, pancreas, sweat glands, digestive and reproductive systems and several other tissues. This debilitating condition is associated with recurrent lower respiratory tract bacterial and viral infections, as well as inflammatory complications that may eventually lead to pulmonary failure. Immune cells play a crucial role in protecting the organs against opportunistic infections and also in the regulation of tissue homeostasis. Innate immune cells are generally affected by CFTR mutations in patients with CF, leading to dysregulation of several cellular signalling pathways that are in continuous use by these cells to elicit a proper immune response. There is substantial evidence to show that airway epithelial cells, neutrophils, monocytes and macrophages all contribute to the pathogenesis of CF, underlying the importance of the CFTR in innate immune responses. The goal of this review is to put into context the important role of the CFTR in different innate immune cells and how CFTR dysfunction contributes to the pathogenesis of CF, highlighting several signalling pathways that may be dysregulated in cells with CFTR mutations.

Gastrointestinal, Pancreatic, and Hepatic Manifestations of Cystic Fibrosis in the Newborn

Gastrointestinal, pancreatic, and hepatic signs and symptoms represent the most common presentation of early disease among patients with cystic fibrosis and may be the initial indication of disease. Regardless of whether cystic fibrosis is diagnosed early by newborn screening or later by clinical course, the impact of gastrointestinal, pancreatic, and hepatic manifestations on early life is nearly ubiquitous. Conditions strongly linked with cystic fibrosis, such as meconium ileus and pancreatic insufficiency, must be recognized and treated early to optimize both short- and long-term care. Similarly, less specific conditions such as reflux, poor weight gain, and cholestasis are frequently encountered in infants with cystic fibrosis. In this population, these conditions may present unique challenges in which early interventions may have significant influence on both short- and long-term morbidity and mortality outcomes.

Digestive enzymes of fungal origin as a relevant cause of false positive Aspergillus antigen testing in intensive care unit patients

Background

Galactomannan antigen (GM) testing is widely used in the diagnosis of invasive aspergillosis (IA). Digestive enzymes play an important role in enzyme substitution therapy in exocrine pancreatic insufficiency. As digestive enzymes of fungal origin like Nortase contain enzymes from Aspergillus, a false-positive result of the test might be possible because of cross-reacting antigens of the cell wall of the producing fungi. We, therefore, asked whether the administration of fungal enzymes is a relevant cause of false-positive GM antigen test results.

Methods

Patients with a positive GM antigen test between January 2016 and April 2020 were included in the evaluation and divided into two groups: group 1—Nortase-therapy, group 2—no Nortase-therapy. In addition, dissolved Nortase samples were analyzed in vitro for GM and β-1,3-D-glucan. For statistical analysis, the chi-squared and Mann‒Whitney U tests were used.

Results

Sixty-five patients were included in this evaluation (30 patients receiving Nortase and 35 patients not receiving Nortase). The overall false positivity rate of GM testing was 43.1%. Notably, false-positive results were detected significantly more often in the Nortase group (73.3%) than in the control group (17.1%, p < 0.001). While the positive predictive value of GM testing was 0.83 in the control group, there was a dramatic decline to 0.27 in the Nortase group. In vitro analysis proved that the Nortase enzyme preparation was highly positive for the fungal antigens GM and β-1,3-D-glucan.

Conclusions

Our data demonstrate that the administration of digestive enzymes of fungal origin like Nortase leads to a significantly higher rate of false-positive GM test results compared to that in patients without digestive enzyme treatment.

Impact of gastrointestinal physiology on drug absorption in special populations--An UNGAP review

The release and absorption profile of an oral medication is influenced by the physicochemical properties of the drug and its formulation, as well as by the anatomy and physiology of the gastrointestinal (GI) tract. During drug development the bioavailability of a new drug is typically assessed in early clinical studies in a healthy adult population. However, many disease conditions are associated with an alteration of the anatomy and/or physiology of the GI tract. The same holds true for some subpopulations, such as paediatric or elderly patients, or populations with different ethnicity. The variation in GI tract conditions compared to healthy adults can directly affect the kinetics of drug absorption, and thus, safety and efficacy of an oral medication. This review provides an overview of GI tract properties in special populations compared to healthy adults and discusses how drug absorption is affected by these conditions. Particular focus is directed towards non-disease dependent conditions (age, sex, ethnicity, genetic factors, obesity, pregnancy), GI diseases (ulcerative colitis and Crohn's disease, celiac disease, cancer in the GI tract, Roux-en-Y gastric bypass, lactose intolerance, Helicobacter pylori infection, and infectious diseases of the GI tract), as well as systemic diseases that change the GI tract conditions (cystic fibrosis, diabetes, Parkinson's disease, HIV enteropathy, and critical illness). The current knowledge about GI conditions in special populations and their impact on drug absorption is still limited. Further research is required to improve confidence in pharmacokinetic predictions and dosing recommendations in the targeted patient population, and thus to ensure safe and effective drug therapies.

Fecal dysbiosis in infants with cystic fibrosis is associated with early linear growth failure

Most infants with cystic fibrosis (CF) have pancreatic exocrine insufficiency that results in nutrient malabsorption and requires oral pancreatic enzyme replacement. Newborn screening for CF has enabled earlier diagnosis, nutritional intervention, and enzyme replacement for these infants, allowing most infants with CF to achieve their weight goals by 12 months of age¹. Nevertheless, most infants with CF continue to have poor linear growth during their first year of life¹. Although this early linear growth failure is associated with worse long-term respiratory function and survival^2,3, the determinants of stature in infants with CF have not been defined. Several characteristics of the CF gastrointestinal (GI) tract, including inflammation, maldigestion and malabsorption, could promote intestinal dysbiosis^4,5. As GI microbiome activities are known to affect endocrine functions^6,7, the intestinal microbiome of infants with CF might also impact growth. We identified an early, progressive fecal dysbiosis that distinguished infants with CF and low length from infants with CF and normal length. This dysbiosis included altered abundances of taxa that perform functions important for GI health, nutrient harvest, and growth hormone signaling, including decreased Bacteroidetes and increased Proteobacteria. Thus, the GI microbiota represent a potential therapeutic target to correct linear growth defects among infants with CF.

A non-randomised single centre cohort study, comparing standard and modified bowel preparations, in adults with cystic fibrosis requiring colonoscopy

BACKGROUND

Adults with cystic fibrosis (CF) have been reported to be at five to ten-fold risk (25 to 30 fold risk after solid organ transplant) of colorectal cancer (CRC) than the general population. Limited publications to date have reported on practical aspects of achieving adequate colonic cleanse producing good visualisation. In this study, we compared two bowel preparation regimens, standard bowel preparation and a modified CF bowel preparation.

METHODS

A non-randomised study of adults with CF attending a single centre, requiring colonoscopy investigation were selected. Between 2001 and 2015, 485 adults with CF attended the clinic; 70 adults with CF had an initial colonoscopy procedure. After five exclusions, standard bowel preparation was prescribed for 27 patients, and modified CF bowel preparation for 38 patients. Demographic and clinical data were collected for all consenting patients.

RESULTS

There was a significant difference between modified CF bowel preparation group and standard bowel preparation group in bowel visualisation outcomes, with the modified CF bowel preparation group having a higher proportion of "excellent/good" GI visualisation cleanse (50.0% versus 25.9%) and lower rates of "poor" visualisation cleanse (10.5% versus 44.5%) than standard bowel preparation (p = 0.006). Rates of "fair" GI cleanse visualisation were similar between the two groups (39.4% versus 29.6%) (Additional file 1: Table S1). Detection rates of adenomatous polyps at initial colonoscopy was higher in modified CF bowel preparation cohort than with standard preparation group (50.0% versus 18.5%, p < 0.01). Positive adenomatous polyp detection rate in patient's age > 40 years of age was higher (62.5%) than those < 40 years of age (24.3%) (p = 0.003). Colonic adenocarcinoma diagnosis was similar in both groups.

CONCLUSION

This study primarily highlights that standard colonoscopy bowel preparation is often inadequate in patients with CF, and that colonic lavage using modified CF bowel preparation is required to obtain good colonic visualisation. A higher rate of polyps in patients over 40 years of age (versus less than 40 years) was evident. These results support adults with CF considered for colonoscopy screening at 40 years of age, or prior to this if symptomatic; which is earlier than CRC screening in the non-CF Australian population.

Two CFTR mutations within codon 970 differently impact on the chloride channel functionality

Pharmacological rescue of mutant cystic fibrosis transmembrane conductance regulator (CFTR) in cystic fibrosis (CF) depends on the specific defect caused by different mutation classes. We asked whether a patient with the rare p.Gly970Asp (c.2909G>A) mutation could benefit from CFTR pharmacotherapy since a similar missense mutant p.Gly970Arg (c.2908G>C) was previously found to be sensitive to potentiators in vitro but not in vivo. By complementary DNA transfection, we found that both mutations are associated with defective CFTR function amenable to pharmacological treatment. However, analysis of messenger RNA (mRNA) from patient's cells revealed that c.2908G>C impairs RNA splicing whereas c.2909G>A does not perturb splicing and leads to the expected p.Gly970Asp mutation. In agreement with these results, nasal epithelial cells from the p.Gly970Asp patient showed significant improvement of CFTR function upon pharmacological treatment. Our results underline the importance of controlling the effect of CF mutation at the mRNA level to determine if the pharmacotherapy of CFTR basic defect is appropriate.

Cystic Fibrosis: Clinical Phenotypes in Children and Adolescents

PURPOSE

The objective of this study was to describe the clinical phenotypes of children and adolescents with cystic fibrosis (CF); and to assess the role of pancreatic insufficiency and neonatal screening in diagnosis.

METHODS

A cross-sectional study was conducted, which included 77 patients attending a reference center of CF between 2014 and 2016. Epidemiological data, anthropometric measurements, and the presence of pulmonary, pancreatic, gastrointestinal and hepatobiliary manifestations were evaluated based on clinical data and complementary examinations.

RESULTS

Of the 77 patients, 51.9% were male, with a median age of 147 months (7.0-297.0 months), and the majority showed adequate nutritional status. The most common phenotype was pulmonary (92.2%), followed by pancreatic (87.0%), with pancreatic insufficiency in most cases. Gastrointestinal manifestation occurred in 46.8%, with constipation being the more common factor. Hepatobiliary disease occurred in 62.3% of patients. The group with pancreatic insufficiency was diagnosed earlier (5.0 months) when compared to the group with sufficiency (84.0 months) (p=0.01). The age of diagnosis was reduced following implementation of neonatal screening protocols for CF (6.0 months before vs. 3.0 months after, p=0.02).

CONCLUSION

The pulmonary phenotype was the most common, although extrapulmonary manifestations were frequent and clinically relevant, and should mandate early detection and treatment. Neonatal screening for CF led to earlier diagnosis in patients with pancreatic failure, and therefore, should be adopted universally.

IVACAFTOR restores FGF19 regulated bile acid homeostasis in cystic fibrosis patients with an S1251N or a G551D gating mutation

OBJECTIVE

Disruption of the enterohepatic circulation of bile acids (BAs) is part of the gastrointestinal phenotype of cystic fibrosis (CF). Ivacaftor (VX-770), a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator, improves pulmonary function in CF patients with class III gating mutations. We studied the effect of ivacaftor on the enterohepatic circulation by assessing markers of BA homeostasis and their changes in CF patients.

METHODS

In CF patients with an S1251N mutation (N = 16; age 9-35 years S125N study/NTR4873) or a G551D mutation (N = 101; age 10-24 years; GOAL study/ NCT01521338) we analyzed plasma fibroblast growth factor 19 (FGF19) and 7α-hydroxy-4-cholesten-3-one (C4) levels, surrogate markers for intestinal BA absorption and hepatic synthesis, respectively, before and after treatment with ivacaftor.

RESULTS

At baseline, median FGF19 was lower (52% and 53%, P < .001) and median C4 higher (350% and 364%, P < .001), respectively, for the S1251 N and G551D mutation patient groups compared to healthy controls. Treatment with ivacaftor significantly increased FGF19 and reduced C4 levels towards normalization in both cohorts but this did not correlate with CFTR function in other organs, as measured by sweat chloride levels or pulmonary function.

CONCLUSIONS

We demonstrate that patients with CFTR gating mutations display interruption of the enterohepatic circulation of BAs reflected by lower FGF19 and elevated C4 levels. Treatment with ivacaftor partially restored this disruption of BA homeostasis. The improvement did not correlate with established outcome measures of CF, suggesting involvement of modulating factors of CFTR correction in different organs.

Gastrointestinal pathophysiology and nutrition in cystic fibrosis

Cystic fibrosis (CF) is a severe, progressive, multisystemic disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene. Optimizing nutrition is critical, as higher growth parameters are associated with better pulmonary function and outcomes, but unfortunately patients with this disease are prone to malnutrition, growth failure, and vitamin deficiencies. The purpose of this review is to provide a timely highlight of the physiologic processes and outcome data to support today's management strategies, as well as review these principles themselves. Areas covered: This review covers the background of the importance of vigilant attention to nutrition and growth in these patients, the underlying physiology leading to an abnormal gastrointestinal tract and its role in CF malnutrition, and current evaluation and management strategies to address nutrition in CF. Analysis of up-to-date relevant literature was performed using PubMed. Expert commentary: Advances in research and clinical developments over the years have improved knowledge of this disease as well as patient outcomes. Of particular importance is optimizing nutrition especially in the early stages of life, as well as accounting for the markedly abnormal CF intestinal milieu when addressing the gastrointestinal and nutritional needs of these patients.

Practical approach to the gastrointestinal manifestations of cystic fibrosis

Cystic fibrosis (CF) is the most common, life-shortening, genetic illness affecting children in Australia and New Zealand. The genetic abnormality results in abnormal anion transport across the apical membrane of epithelial cells in a number of organs, including the lungs, gastrointestinal tract, liver and genito-urinary tract. Thus, CF is a multi-system disorder that requires a multi-disciplinary approach. Respiratory disease is the predominant cause of both morbidity and mortality in patients with CF. However, there are significant and clinically relevant gastrointestinal, liver, pancreatic and nutritional manifestations that must be detected and managed in a timely and structured manner. The aim of this review is to provide evidence-based information and clinical algorithms to guide the nutritional and gastrointestinal management of patients with CF.

Reduction of Recurrence Risk of Pancreatitis in Cystic Fibrosis With Ivacaftor: Case Series

The effect of ivacaftor in patients with cystic fibrosis (CF) with recurrent pancreatitis is unknown. We conducted a multicenter retrospective study of patients with CF taking ivacaftor who had a history of recurrent pancreatitis. During the first 3 months of therapy, only 1 of the 6 patients had an episode of pancreatitis, which was managed on an outpatient basis. Between 3 and 12 months on ivacaftor therapy, none of the patients had recurrence of pancreatitis or required hospitalization. The use of ivacaftor was associated with a reduced frequency and recurrence rate of pancreatitis in patients with CF.

CFTR is a potential marker for nasopharyngeal carcinoma prognosis and metastasis

While there is an increasing interest in the correlation of cystic fibrosis transmembrane conductance regulator (CFTR) and cancer incidence, the role of CFTR in nasopharyngeal carcinoma (NPC) development remains unknown. In this study, we aimed to explore the prognostic value of CFTR in NPC patients. The expression of CFTR was determined in NPC cell lines and tissues. Statistical analysis was utilized to evaluate the correlation between CFTR expression levels and clinicopathological characteristics and prognosis in 225 cases of NPC patients. The results showed that CFTR was down-regulated in NPC tissues and cell lines. Low expression of CFTR was correlated with advanced stage (p = 0.026), distant metastasis (p < 0.001) and poor prognosis (p < 0.01). Multivariate analysis identified CFTR as an independent prognostic factor (p = 0.003). Additionally, wound healing and transwell assays revealed that overexpression of CFTR inhibited NPC cell migration and invasion, whereas knockdown of CFTR promoted cell migration and invasion. Thus, the current study indicates that CFTR, as demonstrated to play an important role in tumor migration and invasion, may be used as a potential prognostic indicator in NPC.

Variceal Hemorrhage and Adverse Liver Outcomes in Patients With Cystic Fibrosis Cirrhosis

OBJECTIVES

Cirrhosis occurs in 5% to 10% of cystic fibrosis (CF) patients, often accompanied by portal hypertension. We analyzed 3 adverse liver outcomes, variceal bleeding (VB), liver transplant (LT), and liver-related death (LD), and risk factors for these in CF Foundation Patient Registry subjects with reported cirrhosis.

METHODS

We determined 10-year incidence rates for VB, LT, LD, and all-cause mortality (ACM), and examined risk factors using competing risk models and Cox-proportional hazard regression.

RESULTS

From 2003 to 2012, 943 participants (41% females, mean age 18.1 years) had newly reported cirrhosis; 24.7% required insulin, 85% had previous pseudomonas. Seventy-three subjects had reported VB: 38 with first VB and new cirrhosis reported simultaneously and 35 with VB after cirrhosis report. Ten-year cumulative VB, LT, and LD rates were 6.6% (95% confidence interval [CI]: 4.0, 9.1%), 9.9% (95% CI: 6.6%, 13.2%), and 6.9% (95% CI: 4.0%, 9.8%), respectively, with an ACM of 39.2% (95% CI: 30.8, 36.6%). ACM was not increased in subjects with VB compared to those without (hazard ratio [HR] 1.10, 95% CI: 0.59, 2.08). CF-related diabetes (HR: 3.141, 95% CI:1.56, 6.34) and VB (HR: 4.837, 95% CI: 2.33, 10.0) were associated with higher LT risk, whereas only worse lung function was associated with increased LD in multivariate analysis. Death rate among subjects with VB was 24% with LT and 20.4% with native liver.

CONCLUSIONS

VB is an uncommon complication of CF cirrhosis and can herald the diagnosis, but does not affect ACM. Adverse liver outcomes and ACM are frequent by 10 years after cirrhosis report.

Personalized medicine in CF: from modulator development to therapy for cystic fibrosis patients with rare CFTR mutations

Cystic fibrosis (CF) is the most common life-shortening genetic disease affecting ~1 in 3,500 of the Caucasian population. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. To date, more than 2,000 CFTR mutations have been identified, which produce a wide range of phenotypes. The CFTR protein, a chloride channel, is normally expressed on epithelial cells lining the lung, gut, and exocrine glands. Mutations in CFTR have led to pleiotropic effects in CF patients and have resulted in early morbidity and mortality. Research has focused on identifying small molecules, or modulators, that can restore CFTR function. In recent years, two modulators, ivacaftor (Kalydeco) and lumacaftor/ivacaftor (Orkambi), have been approved by the U.S. Food and Drug Administration to treat CF patients with certain CFTR mutations. The development of these modulators has served as proof-of-concept that targeting CFTR by modulators is a viable therapeutic option. Efforts to discover new modulators that could deliver a wider and greater clinical benefit are still ongoing. However, traditional randomized controlled trials (RCTs) require large numbers of patients and become impracticable to test the modulators' efficacy in CF patients with CFTR mutations at frequencies much lower than 1%, suggesting the need for personalized medicine in these CF patients.

The treatment of the pulmonary and extrapulmonary manifestations of cystic fibrosis

Cystic fibrosis (CF) is a complex multisystem disease with considerable between patient variability in its manifestations and severity. In the past several decades, the range of treatments and the evidence to support their use for the pulmonary and extrapulmonary manifestations of CF have increased dramatically, contributing to the improved median survival of patients. As therapy for CF has evolved, new challenges including treatment adherence, medication intolerance and allergy, medical complications and coping with the burden of disease in the context of having a family and managing employment have arisen. While the majority of current therapy focuses primarily on improving symptoms, new therapies (CFTR modulators) target the underlying genetic defect.

Determinants of Serum Glycerophospholipid Fatty Acids in Cystic Fibrosis

The etiology of altered blood fatty acid (FA) composition in cystic fibrosis (CF) is understood only partially. We aimed to investigate the determinants of serum glycerophospholipids’ FAs in CF with regard to the highest number of FAs and in the largest cohort to date. The study comprised 172 CF patients and 30 healthy subjects (HS). We assessed Fas’ profile (gas chromatography/mass spectrometry), CF transmembrane conductance regulator (CFTR) genotype, spirometry, fecal elastase-1, body height and weight Z-scores, liver disease, diabetes and colonization by Pseudomonas aeruginosa. The amounts of saturated FAs (C14:0, C16:0) and monounsaturated FAs (C16:1n-7, C18:1n-9, C20:1n-9, C20:3n-9) were significantly higher in CF patients than in HS. C18:3n-6, C20:3n-6 and C22:4n-6 levels were also higher in CF, but C18:2n-6, C20:2n-6 and C20:4n-6, as well as C22:6n-3, were lower. In a multiple regression analysis, levels of seven FAs were predicted by various sets of factors that included age, genotype, forced expiratory volume in one second, pancreatic status and diabetes. FA composition abnormalities are highly prevalent in CF patients. They seem to be caused by both metabolic disturbances and independent clinical risk factors. Further research into the influence of CFTR mutations on fat metabolism and desaturases’ activity is warranted.

Microbiome in the pathogenesis of cystic fibrosis and lung transplant-related disease

Significant advances in culture-independent methods have expanded our knowledge about the diversity of the lung microbial environment. Complex microorganisms and microbial communities can now be identified in the distal airways in a variety of respiratory diseases, including cystic fibrosis (CF) and the posttransplantation lung. Although there are significant methodologic concerns about sampling the lung microbiome, several studies have now shown that the microbiome of the lower respiratory tract is distinct from the upper airway. CF is a disease characterized by chronic airway infections that lead to significant morbidity and mortality. Traditional culture-dependent methods have identified a select group of pathogens that cause exacerbations in CF, but studies using bacterial 16S rRNA gene-based microarrays have shown that the CF microbiome is an intricate and dynamic bacterial ecosystem, which influences both host immune health and disease pathogenesis. These microbial communities can shift with external influences, including antibiotic exposure. In addition, there have been a number of studies suggesting a link between the gut microbiome and respiratory health in CF. Compared with CF, there is significantly less knowledge about the microbiome of the transplanted lung. Risk factors for bronchiolitis obliterans syndrome, one of the leading causes of death, include microbial infections. Lung transplant patients have a unique lung microbiome that is different than the pretransplanted microbiome and changes with time. Understanding the host-pathogen interactions in these diseases may suggest targeted therapies and improve long-term survival in these patients.