Cystic fibrosis screening, evaluation, and management of hepatobiliary disease consensus recommendations.

Cystic fibrosis (CF) may cause a spectrum of hepatobiliary complications, including portal hypertension, multilobular cirrhosis, and liver failure. Current guidelines on the detection and monitoring of hepatobiliary complications in CF were published in 1999. The CF Foundation assembled a committee to evaluate research advances and formulate revised guidelines for CF-associated liver disease. A committee of hepatologists, gastroenterologists, pulmonologists, pharmacists, nurses, dietitians, individuals with CF, and the parents of a child with CF devised "population, intervention, comparison, and outcome" questions regarding hepatobiliary disease in CF. PubMed literature searches were performed for each population, intervention, comparison, and outcome question. Recommendations were voted on with 80% agreement required to approve a recommendation. Public comment on initial recommendations was solicited prior to the formulation of final recommendations. Thirty-one population, intervention, comparison, and outcome questions were assembled, 6401 manuscripts were title screened for relevance, with 1053 manuscripts undergoing detailed full-text review. Seven recommendations were approved for screening, 13 for monitoring of existing disease, and 14 for treatment of CF-associated hepatobiliary involvement or advanced liver disease. One recommendation on liver biopsy did not meet the 80% threshold. One recommendation on screening ultrasound was revised and re-voted on. Through a multidisciplinary committee and public engagement, we have assembled updated recommendations and guidance on screening, monitoring, and treatment of CF-associated hepatobiliary involvement and advanced liver disease. While research gaps remain, we anticipate that these recommendations will lead to improvements in CF outcomes through earlier detection and increased evidence-based approaches to monitoring and treatment.

Intrahepatic Cholangiolitis in Cystic Fibrosis (ICCF): An Under-Appreciated Cause of Persistent Cholestasis in Infancy.

Liver histology in infants with cystic fibrosis (CF) and persistent cholestasis is seldom reported in detail. We extend previous observation of a distinctive intrahepatic cholangiopathy (ICCF) to 3 additional infants homozygous for CFTR pathological variants and a fourth infant with a heterozygous CFTR variant, summarizing our experience in 10 infants with CFTR variants and persistent cholestasis. Cholangiograms demonstrate abnormal extrahepatic ducts in 2 infants with CF, 1 with uniform dilatation interpreted as a choledochal cyst and the other with narrow patent ducts. Liver histology in 3 CF homozygotes had prominent ductular reaction with a focally destructive cholangiolitis (inflammation of small bile ducts). The CFTR heterozygote had generalized portal edema with ductular reaction and paucity but no cholangitis. Cholestasis slowly subsided in all infants. ICCF is characterized by severe ductular reaction, prominent cholangiocyte injury, and multifocal necrotizing cholangiolitis. Local aggregates of portal ceroid might suggest previous bile leakage from damaged ducts. ICCF in liver biopsies from infants with cystic fibrosis and persistent cholestasis is unrelated to the specific CFTR genotype. Liver biopsy findings and intraoperative cholangiogram help rule out biliary atresia. ICCF is an early manifestation of CF, a likely prototype for pathogenesis of cystic fibrosis liver disease later in life.

Cystic fibrosis hepatobiliary involvement: an update on imaging in diagnosis and monitoring.

Analysis of the liver using imaging for persons with cystic fibrosis (CF) continues to evolve as new medical therapies are developed improving and extending life. In the 2010s, therapies targeted at modulating protein folding became available to those with CF. Therapeutic options have continued to expand, now providing both correction of protein folding and stabilization for most gene mutations that code for the CF transmembrane receptor protein (CFTR). Today, approximately 80% of persons with CF are eligible for highly effective modulator therapy. With these advancements, the impact of CF on the liver has become more complex, adding metabolism of CFTR modulators to intrinsic CF hepatobiliary involvement (CFHBI) and adding not previously appreciated vascular changes within the liver due to increased longevity in persons with CF. A combination of serum biomarkers and imaging is needed to add clarity to the diagnosis and monitoring of the severity of liver disease. A substantial portion of persons with CF will develop at least CFHBI and a subset will develop advanced cystic fibrosis-associated liver disease (aCFLD); therefore, diagnosis and monitoring need to begin in childhood. In this review, we cover the use of and need for imaging, including elastography, ultrasound, and magnetic resonance imaging (MRI), in diagnosing and monitoring CFHBI and its associated complications.

Evaluation of the Use of Appetite Stimulants in Pediatric Patients with Cystic Fibrosis.

OBJECTIVE: Poor nutrition in patients with cystic fibrosis (CF) has been associated with lower lung function and increased morbidity and mortality. Conversely, better nutritional status has been associated with improved pulmonary function and fewer CF-associated complications. There is no consensus regarding appetite stimulant therapy in patients with CF (pwCF). The primary objective of this study was to determine if the use of appetite stimulants was associated with weight changes in pediatric pwCF in the ambulatory care setting. METHODS: This was a retrospective study that evaluated 62 pediatric pwCF who received cyproheptadine or mirtazapine for appetite stimulation for at least 6 consecutive months. Weight z scores were collected for each patient at baseline, 3, 6, and 12 months of therapy, if available. RESULTS: Increase in weight z score after 3 months of therapy was statistically significant based on both univariable and multivariable models when evaluating the entire cohort. The adjusted mean difference for change in weight z score was 0.33 ( P < 0.001) from baseline to month 3. There was a statistically significant improvement in pulmonary function after 3 and 6 months of therapy. CONCLUSIONS: Appetite stimulant therapy was associated with improvement in weight z score in the first 3 months of treatment. Appetite stimulant therapy was associated with improvement in pulmonary function in the first 3 months of therapy, which supports the relationship between weight gain and improved pulmonary function in pwCF. These findings suggest that appetite stimulants contribute to weight gain in pediatric pwCF, particularly within the first 3 months of therapy.

Patient Attitudes Regarding Health Care Clinician Communication in Adolescents With Cystic Fibrosis.

BACKGROUND: The quality of health care clinician (HCC) communication varies, yet few studies evaluate ways to improve communication among adolescents with cystic fibrosis (CF). We sought to characterize the attitudes of adolescents and young adults (AYA) with CF about HCC communication and describe the components important for high-quality communication. METHODS: AYA with CF aged 12-20 years from a single large pediatric CF care center participated in a brief survey and semi-structured individual and group virtual interviews that were recorded, transcribed, coded, and analyzed with a combined deductive and inductive approach. Discrepancies were resolved by consensus. RESULTS: Among the 39 survey respondents, most were White (77%), male (51%), and averaged 15.51 years (range 12-20 years). Many (40%) perceived their health status as " neutral " and over half (61%) were " very satisfied " with HCC communication. Overall, among the 17 interviews (averaged 53.6 min, range 31.5-74 min), participants reported a desire to be actively engaged in discussions about their health and included in the decision-making process with HCC to support adolescent autonomy and cultivate trust. Some factors detract (loss of control and fear of diagnosis), and others strengthen (transition to adult care and external motivators) adolescent autonomy. Some factors detract (perceived lack of interdisciplinary communication, statements of noncompliance, and being compared to others) and others strengthen (inherent trust and familiarity over time) the cultivation of trust. CONCLUSIONS: The development of adolescent autonomy and the cultivation and maintenance of trust between the patient and HCC are 2 essential components of quality communication that should inform future communication-focused interventions.

Evaluation of the Effectiveness of In-line Immobilized Lipase Cartridge in Enterally Fed Patients With Cystic Fibrosis.

BACKGROUND: Pancreatic insufficiency occurs in most patients with cystic fibrosis (CF) contributing to malnutrition. In the United States, 3600 patients with CF require enteral feeding (EF). Oral pancreatic enzymes are commonly used with EF, despite not being designed or approved for this use. An immobilized lipase cartridge (ILC) for extracorporeal digestion of enteral feedings was developed. The sponsor provided it to patients via a structured program, which we evaluated to assess the effectiveness of the ILC on nutritional status. METHODS: The program provided the ILC to patients prescribed the device while reimbursement efforts were ongoing. Baseline anthropometric data were obtained and subsequent measurements of height, weight, and body mass index (BMI) were collected at 6 and 12 months. RESULTS: Inclusion criteria were met by 100 patients (age = 0--45 years). Over 12 months of use in patients >2 years of age (n = 93), there were significant improvements seen in height and weight z-scores with improvement trend seen in BMI. The frequency of achieving the 50th percentile increased steadily for weight and BMI from baseline to 12 months but not for height. CONCLUSIONS: This evaluation of a program to assist patient access to ILC demonstrates that better growth is possible over standard of care. The association of ILC use with significant improvements in anthropometric parameters over a 12-month period in people with CF demonstrates the effectiveness of ILC as rational enzyme therapy during enteral feedings.

Gastrointestinal Factors Associated With Hospitalization in Infants With Cystic Fibrosis: Results From the Baby Observational and Nutrition Study.

OBJECTIVES: To identify factors that increase the risk of gastrointestinal-related (GI-related) hospitalization of infants with cystic fibrosis (CF) during the first year of life. METHODS: The Baby Observational and Nutrition Study was a longitudinal, observational cohort of 231 infants diagnosed with CF by newborn screening. We performed a post-hoc assessment of the frequency and indications for GI-related admissions during the first year of life. RESULTS: Sixty-five participants had at least one admission in the first 12 months of life. High pancreatic enzyme replacement therapy (PERT) dosing (>2000 lipase units/kg per meal; hazard ratio [HR] = 14.75, P = 0.0005) and use of acid suppressive medications (HR = 4.94, P = 0.01) during the study period were positively associated with subsequent GI-related admissions. High levels of fecal calprotectin (fCP) (>200 µg/g) and higher relative abundance of fecal Klebsiella pneumoniae were also positively associated with subsequent GI-related admissions (HR = 2.64, P = 0.033 and HR = 4.49, P = 0.002, respectively). During the first 12 months of life, participants with any admission had lower weight-for-length z scores (WLZ) (P = 0.01). The impact of admission on WLZ was particularly evident in participants with a GI-related admission (P < 0.0001). CONCLUSIONS: Factors associated with a higher risk for GI-related admission during the first 12 months include high PERT dosing, exposure to acid suppressive medications, higher fCP levels, and/or relative abundance of fecal K pneumoniae early in life. Infants with CF requiring GI-related hospitalization had lower WLZ at 12 months of age than those not admitted as well as those admitted for non-GI-related indications.

Association of in-line digestive enzyme cartridge with enteral feeds on improvement in anthropometrics among pediatric patients with cystic fibrosis.

BACKGROUND: Approximately 85% of patients with cystic fibrosis (CF) have exocrine pancreatic insufficiency (EPI) with 10% requiring supplemental nighttime enteral tube feedings. Administration of pancreatic enzyme replacement therapy (PERT) with nighttime feedings is fraught with challenges. RELiZORB (Alcresta Therapeutics, Inc), an in-line lipase cartridge, delivers PERT continuously with enteral feedings. Outcomes related to the use of this in-line lipase cartridge are lesser known. This project evaluated anthropometrics related to in-line lipase cartridge use among pediatric patients with CF already receiving oral PERT therapy prior to nighttime enteral feedings. METHODS: Retrospective chart review was performed on 29 patients with CF and EPI receiving supplemental tube feedings and utilizing in-line lipase cartridge for a continuous 12 month period between 2015 and 2019. Anthropometrics were evaluated 12 months before and after initiation of in-line lipase cartridge. RESULTS: Compared with mean height z score at 6-months pre-in-line lipase cartridge, mean height z score at 6-months post-in-line-lipase cartridge (adjusted mean difference [AMD] = 0.2540; 95% CI = [0.0487, 0.4592]; P = 0.0153) and mean height z score at 12-months post-in-line lipase cartridge (AMD = 0.2684; 95% CI = [0.0203, 0.5166]; P = 0.0340) were significantly higher. Mean weight z score at 12-months post-in-line-lipase-cartridge neared statistical significance compared with 6-months pre-in-line lipase cartridge (AMD = 0.2816; 95% CI = [-0.0003, 0.5634]; P = 0.0502) when excluding seven patients with advanced lung disease (forced expiratory volume in the first second of expiration of 40%). Weight-for-length or body mass index did not significantly differ compared with pre-in-line lipase cartridge. CONCLUSION: Use of in-line lipase cartridge with enteral feeds improved anthropometrics, especially height, in pediatric patients with CF.

Cross-Cutting mHealth Behavior Change Techniques to Support Treatment Adherence and Self-Management of Complex Medical Conditions: Systematic Review.

Background: Mobile health (mHealth) interventions have immense potential to support disease self-management for people with complex medical conditions following treatment regimens that involve taking medicine and other self-management activities. However, there is no consensus on what discrete behavior change techniques (BCTs) should be used in an effective adherence and self-management-promoting mHealth solution for any chronic illness. Reviewing the extant literature to identify effective, cross-cutting BCTs in mHealth interventions for adherence and self-management promotion could help accelerate the development, evaluation, and dissemination of behavior change interventions with potential generalizability across complex medical conditions. Objective: This study aimed to identify cross-cutting, mHealth-based BCTs to incorporate into effective mHealth adherence and self-management interventions for people with complex medical conditions, by systematically reviewing the literature across chronic medical conditions with similar adherence and self-management demands. Methods: A registered systematic review was conducted to identify published evaluations of mHealth adherence and self-management interventions for chronic medical conditions with complex adherence and self-management demands. The methodological characteristics and BCTs in each study were extracted using a standard data collection form. Results: A total of 122 studies were reviewed; the majority involved people with type 2 diabetes (28/122, 23%), asthma (27/122, 22%), and type 1 diabetes (19/122, 16%). mHealth interventions rated as having a positive outcome on adherence and self-management used more BCTs (mean 4.95, SD 2.56) than interventions with no impact on outcomes (mean 3.57, SD 1.95) or those that used >1 outcome measure or analytic approach (mean 3.90, SD 1.93; P=.02). The following BCTs were associated with positive outcomes: self-monitoring outcomes of behavior (39/59, 66%), feedback on outcomes of behavior (34/59, 58%), self-monitoring of behavior (34/59, 58%), feedback on behavior (29/59, 49%), credible source (24/59, 41%), and goal setting (behavior; 14/59, 24%). In adult-only samples, prompts and cues were associated with positive outcomes (34/45, 76%). In adolescent and young adult samples, information about health consequences (1/4, 25%), problem-solving (1/4, 25%), and material reward (behavior; 2/4, 50%) were associated with positive outcomes. In interventions explicitly targeting medicine taking, prompts and cues (25/33, 76%) and credible source (13/33, 39%) were associated with positive outcomes. In interventions focused on self-management and other adherence targets, instruction on how to perform the behavior (8/26, 31%), goal setting (behavior; 8/26, 31%), and action planning (5/26, 19%) were associated with positive outcomes. Conclusions: To support adherence and self-management in people with complex medical conditions, mHealth tools should purposefully incorporate effective and developmentally appropriate BCTs. A cross-cutting approach to BCT selection could accelerate the development of much-needed mHealth interventions for target populations, although mHealth intervention developers should continue to consider the unique needs of the target population when designing these tools.

Remote endpoints for clinical trials in cystic fibrosis: Report from the U.S. CF foundation remote endpoints task force.

The COVID-19 pandemic necessitated a rapid shift in clinical research to perform virtual visits and remote endpoint assessments, providing a key opportunity to optimize the use of remote endpoints for clinical trials in cystic fibrosis. The use of remote endpoints could allow more diverse participation in clinical trials while minimizing participant burden but must be robustly evaluated to ensure adequate performance and feasibility. In response, the Cystic Fibrosis Foundation convened the Remote Endpoint Task Force (Supplemental Table 1), a multidisciplinary group of CF researchers with remote endpoint expertise and community members tasked to better understand the current and future use of remote endpoints for clinical research. Here, we describe the current use of remote endpoints in CF clinical research, address key unanswered questions regarding their use and feasibility, and discuss the next steps to determine clinical trial readiness.

Validation of an omega-3 substrate challenge absorption test as an indicator of global fat lipolysis.

INTRODUCTION: The coefficient of fat absorption (CFA) quantifies fat that remains in stool after digestion and is not a direct measure of lipolysis. CFA has been used to assess treatment of pancreatic insufficiency but does not correlate with pancreatic enzyme replacement therapy dose. We explored use of an omega-3 substrate absorption challenge test as a sensitive test of lipolysis and absorption. METHODS: We studied a novel microbially-derived lipase (SNSP003) employing an established surgical model commonly used to study the uptake of macronutrients, the exocrine pancreatic insufficient pig. Pigs were fed a high-fat diet and given a standardized omega-3 substrate challenge to test the effect of lipolysis on its absorption. Blood was drawn at 0, 1, 2, 4, 6, 8, 12, and 24 hours following the substrate challenge and was analyzed for omega-3 and total fat levels (c14:c24). SNSP003 was also compard to porcine pancrelipase. RESULTS: The absorption of omega-3 fats was significantly increased following administration of 40, 80 and 120 mg SNSP003 lipase by 51% (p = 0.02), 89%, (p = 0.001) and 64% (p = 0.01), respectively, compared to that observed when no lipase was administered to the pigs, with Tmax at 4 hours. The two highest SNSP003 doses were compared to porcine pancrelipase and no significant differences were observed. Both doses increased plasma total fatty acids (141% for the 80 mg dose (p = 0.001) and 133% for the 120 mg dose (p = 0.006), compared to no lipase) and no significant differences were observed between the SNSP003 lipase doses and porcine pancrelipase. CONCLUSION: The omega-3 substrate absorption challenge test differentiates among different doses of a novel microbially-derived lipase and correlates with global fat lipolysis and absorption in exocrine pancreatic insufficient pigs. No significant differences were observed between the two highest novel lipase doses and porcine pancrelipase. Studies in humans should be designed to support the evidence presented here that suggests the omega-3 substrate absorption challenge test has advantages over the coefficient of fat absorption test to study lipase activity.

The use of DXA for early detection of pediatric cystic fibrosis-related bone disease.

BACKGROUND: Cystic fibrosis (CF)-related bone disease (CFBD) is seen in adults and can be associated with respiratory illness and malnutrition. There is limited and conflicting data regarding CFBD in pediatric CF. With longer life expectancy and promotion of disease prevention, pediatric CFBD demands further investigation. METHODS: Our center initiated a quality improvement (QI) project from April 2016 to December 2018 to improve CFBD screening in patients 8 years or older, per current CF Foundation (CFF) guidelines. Our team formulated a dual-energy X-ray absorptiometry (DXA) scan algorithm based upon degree of bone mineral density (BMD); shared CFBD guideline recommendations in our quarterly newsletter; and ordered scans for eligible patients at weekly review meetings. We reviewed DXA results from 141 patients after institutional review board approval and gathered data including comorbidities, genetics, anthropometric measures, medication exposure, and relevant serum studies. RESULTS: Fifty-three percent of our patients had normal BMD (n = 75). Seventeen patients (12%) had a Z score ≤ -2. Patients with lower BMD also had lower mean forced expiratory volume (FEV1 ) percent predicted (FEV1 %) (p < 0.001) as well as lower body mass index % (p = 0.001). Patients with lower BMD were overall older at time of DXA (p = 0.016). During study duration, 13 patients who had abnormal DXA results underwent repeat DXAs after physical therapy; 11 of the 13 showed improvement in DXA results. CONCLUSIONS: A DXA scan is a useful screening tool and can be used to identify pediatric patients who could benefit from further therapy and interventions to preserve adequate bone health and avoid further loss. QI initiatives can lead to improved screening and diagnosis and earlier intervention such as physical therapy. Further studies are needed to better understand the utility of physical therapy in children with CF.

Standardizing and optimizing nutrition evaluation frequency of enterally fed patients in an ambulatory pediatric gastroenterology practice: A single-center study.

BACKGROUND: Nutrition monitoring is essential in feeding tube-dependent patients receiving home enteral nutrition (HEN). We identified lack of consistency in dietitian evaluations for our pediatric patients receiving HEN. Consequently, after establishing an institutional standard for nutrition reassessment intervals, we underwent a quality improvement (QI) initiative to improve rates of adherence to standard frequency of dietitian consults and referrals among patients receiving HEN. METHODS: A prospective QI initiative from April 2021 to December 2021 was performed using multiple plan-do-study-act (PDSA) cycles. Interventions included (1) a reminder placard, (2) the display of feeding tube status and date of the last dietitian note in the electronic health record (EHR) clinic schedule dashboard, and (3) an autotext smart element to the EHR default clinic note template. The goal was to enable clinicians to quickly identify the need for nutrition evaluation with either a same-day dietitian consult or a referral to nutrition clinic. RESULTS: Among 111 HEN patients with >6 months since last nutrition encounter, the dietitian referral/consult rate prior to any interventions was 58%. The placard (PDSA 1) was abandoned before obtaining reportable data because of sampling bias and clinic workflow inefficiencies. The clinic schedule dashboard modification (PDSA 2) improved the dietitian referral/consult rate to 66%. Subsequently, the clinic note smart element (PDSA 3) increased the rate to 77%. An 8-week postintervention check revealed a compliance rate of 78%. CONCLUSION: Implementation of minimally interruptive EHR enhancements showed a sustained increase in dietitian referrals and consults for patients receiving HEN, which may improve nutrition outcomes.

Need to study simplification of gastrointestinal medication regimen in cystic fibrosis in the era of highly effective modulators.

INTRODUCTION: The success of highly effective modulator therapy (HEMT) has led to consideration of simpler regimens for people with CF (PwCF) with opportunities to modify burdensome regimens. Despite the intuitive appeal of discontinuing chronic therapies no longer necessary, this process should be pursued systematically to ensure safety, adherence, and validate patient-centered preferences. We designed a questionnaire to determine the state of use of acid-suppressive medications (ASM) and pancreatic enzyme therapy (PERT), current self-withdrawal and provider-directed withdrawal practices, and interest in a standardized withdrawal study. METHODS: In collaboration with CF Foundation (CFF), a questionnaire was developed and distributed to members of Community Voice (CV, comprised of PwCF and their loved ones), and CF providers regarding the need to study simplifying the gastrointestinal (GI) regimen for PwCF on HEMT. RESULTS: Approximately 20-40% of CV or CF providers have decreased or stopped ASM for those on HEMT. For PERT, CV and CF providers have decreased dose (34%-48% and approximately 25%, respectively) more often than having stopped it altogether (13%-24% and 3%-12%, respectively). Cumulatively, there is interest in pursuing research in this area (86% CV and 89% CF providers) and willingness to enroll in such a study (80% CV and 89% CF providers). CONCLUSION: Systematically studying the withdrawal of common GI medications, ASM and PERT, is important to CV and CF providers. Decreases in dosing and withdrawal are already taking place without evidence to support this practice. This questionnaire is the first step in designing a GI medication simplification study in PwCF on HEMT.

Multicenter prospective study showing a high gastrointestinal symptom burden in cystic fibrosis.

BACKGROUND AND AIMS: People with cystic fibrosis (PwCF) suffer from gastrointestinal (GI) symptoms affecting their quality of life (QOL). Despite the relevance of GI symptoms to the overall health of PwCF, a paucity of studies only have comprehensively assessed the prevalence, severity and QOL of GI symptoms in both children and adults with Cystic Fibrosis (CF). METHODS: Eligible participants ≥2 years of age across 26 US CF centers were followed for 4 weeks. Three validated GI electronic patient-reported outcome measures (ePROMs) with a recall period of 2 weeks and a stool-specific questionnaire were administered weekly over four weeks. Total and domain scores of ePROMs were evaluated overall and in subgroups using linear mixed-effect models. RESULTS: Of 402 enrolled, 58% were ≥ 18 years of age (52% male). The mean (SD) of the total score for PAC-SYM was 0.52 (0.55), for PAGI-SYM was 0.63 (0.67), and for PAC-QOL was 0.67 (0.55). For specific ePROM questions, prevalence of moderate to very severe symptoms were as follows: straining (20.3%), fullness (18.3%), incomplete bowel movements (17.1%), bloating (16.4%), distension (16.4%), abdominal pain (upper-5.1%, lower-7.5%). Comparing participants ≥18 versus <18, a higher prevalence of bloating (63.7% versus 27.3%), lower abdominal pain (39.8% vs 26.2%), stomach fullness (75.6% versus 56.2%), and abdominal distension (60.2% versus 34.9%) was found. Both age groups reported high treatment dissatisfaction as measured with PAC-QOL, mean 1.39 (95% CI: 1.30, 1.47). CONCLUSION: GI symptoms were reported in all age ranges irrespective of gender, with higher prevalence observed amongst older and female subgroups. Dissatisfaction with GI targeted treatments were reported in a large proportion of participants despite therapy, highlighting an unmet need for clinical interventions. CLINICALTRIALS: GOV: NCT03801993.

Regulation of purinergic signaling in biliary epithelial cells by exocytosis of SLC17A9-dependent ATP-enriched vesicles.

ATP in bile is a potent secretogogue, stimulating biliary epithelial cell (BEC) secretion through binding apical purinergic receptors. In response to mechanosensitive stimuli, BECs release ATP into bile, although the cellular basis of ATP release is unknown. The aims of this study in human and mouse BECs were to determine whether ATP release occurs via exocytosis of ATP-enriched vesicles and to elucidate the potential role of the vesicular nucleotide transporter SLC17A9 in purinergic signaling. Dynamic, multiscale, live cell imaging (confocal and total internal reflection fluorescence microscopy and a luminescence detection system with a high sensitivity charge-coupled device camera) was utilized to detect vesicular ATP release from cell populations, single cells, and the submembrane space of a single cell. In response to increases in cell volume, BECs release ATP, which was dependent on intact microtubules and vesicular trafficking pathways. ATP release occurred as stochastic point source bursts of luminescence consistent with exocytic events. Parallel studies identified ATP-enriched vesicles ranging in size from 0.4 to 1 µm that underwent fusion and release in response to increases in cell volume in a protein kinase C-dependent manner. Present in all models, SLC17A9 contributed to ATP vesicle formation and regulated ATP release. The findings are consistent with the existence of an SLC17A9-dependent ATP-enriched vesicular pool in biliary epithelium that undergoes regulated exocytosis to initiate purinergic signaling.

Understanding Cystic Fibrosis Comorbidities and Their Impact on Nutritional Management.

Cystic fibrosis (CF) is a chronic, multisystem disease with multiple comorbidities that can significantly affect nutrition and quality of life. Maintaining nutritional adequacy can be challenging in people with cystic fibrosis and has been directly associated with suboptimal clinical outcomes. Comorbidities of CF can result in significantly decreased nutritional intake and intestinal absorption, as well as increased metabolic demands. It is crucial to utilize a multidisciplinary team with expertise in CF to optimize growth and nutrition, where patients with CF and their loved ones are placed in the center of the care model. Additionally, with the advent of highly effective modulators (HEMs), CF providers have begun to identify previously unrecognized nutritional issues, such as obesity. Here, we will review and summarize commonly encountered comorbidities and their nutritional impact on this unique population.

Association between stool consistency and clinical variables among infants with cystic fibrosis: Findings from the BONUS study.

BACKGROUND: Concerns related to stool consistency are common in the first year of life among children with cystic fibrosis (CF). However, normal stool patterns for infants with CF have not been described. METHODS: Secondary analysis was completed from the previously described BONUS cohort which followed 231 infants with CF through the first 12 months of life. Pain, stool category, stool frequency, feeding type, PERT dose, acid suppression medication, antibiotics usage, stool softener usage and fecal calprotectin were described at 3, 6, and 12 months. Repeated measure ANOVA was used to test the difference in mean stool number. Generalized linear mixed models were used to investigate the relationship between stool characteristics and various factors. RESULTS: The frequency of constipation was stable throughout the first year of life (10-13%) while watery stool significantly decreased from 21.3% at 3 months to 5.8% at 12 months (p=<0.001). The number of stools at months 6 (mean=2.40) and 12 (mean=2.50) are significantly lower than in month 3 (mean=2.83), p<0.025. Exclusive breast feeding was associated with an increased risk for constipation (OR=2.64  [1.60-4.37], p = 0.002) while exclusive formula feeding and acid suppression was associated with decreased risk for constipation (OR=0.40  [0.26-0.61], p=<0.0001 and OR=0.59  [0.39-0.89], p = 0.01 respectively). Pain was not significantly associated with stool consistency. CONCLUSION: Stool frequency and consistency evolves in infant with CF in a fashion similar to that reported in non-CF infants over the first year. Constipation was not associated with pain and was less common among infants receiving acid suppression or exclusively formula feeding.

The mammalian SKIV2L RNA exosome is essential for early B cell development.

The SKIV2L RNA exosome is an evolutionarily conserved RNA degradation complex in the eukaryotes. Mutations in the SKIV2L gene are associated with a severe inherited disorder, trichohepatoenteric syndrome (THES), with multisystem involvement but unknown disease mechanism. Here, we reported a THES patient with SKIV2L mutations showing severe primary B cell immunodeficiency, hypogammaglobulinemia, and kappa-restricted plasma cell dyscrasia but normal T cell and NK cell function. To corroborate these findings, we made B cell-specific Skiv2l knockout mice (Skiv2lfl/flCd79a-Cre), which lacked both conventional B-2 and innate-like B-1 B cells in the periphery and secondary lymphoid organs. This was linked to a requirement of SKIV2L RNA exosome activity in the bone marrow during early B cell development at the pro-B cell to large pre-B cell transition. Mechanistically, Skiv2l-deficient pro-B cells exhibited cell cycle arrest and DNA damage. Furthermore, loss of Skiv2l led to substantial out-of-frame V(D)J rearrangement of immunoglobulin heavy chain and severely reduced surface expression of µH, both of which are crucial for pre-BCR signaling and proliferative burst during early B cell development. Together, our data demonstrated a crucial role for SKIV2L RNA exosome in early B cell development in both human and mice by ensuring proper V(D)J recombination and Igh expression, which serves as the molecular basis for immunodeficiency associated with THES.

Cytoplasmic RNA quality control failure engages mTORC1-mediated autoinflammatory disease.

Inborn errors of nucleic acid metabolism often cause aberrant activation of nucleic acid sensing pathways, leading to autoimmune or autoinflammatory diseases. The SKIV2L RNA exosome is cytoplasmic RNA degradation machinery that was thought to be essential for preventing the self-RNA-mediated interferon (IFN) response. Here, we demonstrate the physiological function of SKIV2L in mammals. We found that Skiv2l deficiency in mice disrupted epidermal and T cell homeostasis in a cell-intrinsic manner independently of IFN. Skiv2l-deficient mice developed skin inflammation and hair abnormality, which were also observed in a SKIV2L-deficient patient. Epidermis-specific deletion of Skiv2l caused hyperproliferation of keratinocytes and disrupted epidermal stratification, leading to impaired skin barrier with no appreciable IFN activation. Moreover, Skiv2l-deficient T cells were chronically hyperactivated and these T cells attacked lesional skin as well as hair follicles. Mechanistically, SKIV2L loss activated the mTORC1 pathway in both keratinocytes and T cells. Both systemic and topical rapamycin treatment of Skiv2l-deficient mice ameliorated epidermal hyperplasia and skin inflammation. Together, we demonstrate that mTORC1, a classical nutrient sensor, also senses cytoplasmic RNA quality control failure and drives autoinflammatory disease. We also propose SKIV2L-associated trichohepatoenteric syndrome (THES) as a new mTORopathy for which sirolimus may be a promising therapy.