Impact of elexacaftor/tezacaftor/ivacaftor on vitamin D absorption in cystic fibrosis patients.

BACKGROUND: Cystic fibrosis (CF) is a multisystem disorder that results in the buildup of mucus in various organs. Ninety percent of CF patients are classified as pancreatic insufficient, leading to malabsorption of nutrients and fat-soluble vitamins without the assistance of exogenous pancreatic enzymes. This study was designed to determine if serum 25-hydroxyvitamin D concentrations were impacted by initiation of elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA). METHODS: Serum 25-hydroxyvitamin D concentrations were measured before and 1 year post-ELX/TEZ/IVA initiation. A Wilcoxon signed-rank test was used to compare values. RESULTS: Seventy-six patients were included in the final analysis. The average age of our population was 25.8 years (SD = 13.2 years) with a majority being male, homozygous F508del, pancreatic insufficient, and not modulator-naive. The median increase of serum vitamin D concentration after initiating ELX/TEZ/IVA was 5 ng/ml (interquartile range = -4, 13; p = .0035). CONCLUSIONS: We suggest that ELX/TEZ/IVA may improve fat-soluble vitamin absorption, specifically serum 25-hydroxyvitamin D. These results may lead to adjustments in vitamin supplementation in patients receiving cystic fibrosis transmembrane conductance regulator modulator therapy.

ACG Clinical Guideline: Management of Irritable Bowel Syndrome.

Irritable bowel syndrome (IBS) is a highly prevalent, chronic disorder that significantly reduces patients' quality of life. Advances in diagnostic testing and in therapeutic options for patients with IBS led to the development of this first-ever American College of Gastroenterology clinical guideline for the management of IBS using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Twenty-five clinically important questions were assessed after a comprehensive literature search; 9 questions focused on diagnostic testing; 16 questions focused on therapeutic options. Consensus was obtained using a modified Delphi approach, and based on GRADE methodology, we endorse the following: We suggest that a positive diagnostic strategy as compared to a diagnostic strategy of exclusion be used to improve time to initiating appropriate therapy. We suggest that serologic testing be performed to rule out celiac disease in patients with IBS and diarrhea symptoms. We suggest that fecal calprotectin be checked in patients with suspected IBS and diarrhea symptoms to rule out inflammatory bowel disease. We recommend a limited trial of a low fermentable oligosaccharides, disacchardies, monosaccharides, polyols (FODMAP) diet in patients with IBS to improve global symptoms. We recommend the use of chloride channel activators and guanylate cyclase activators to treat global IBS with constipation symptoms. We recommend the use of rifaximin to treat global IBS with diarrhea symptoms. We suggest that gut-directed psychotherapy be used to treat global IBS symptoms. Additional statements and information regarding diagnostic strategies, specific drugs, doses, and duration of therapy can be found in the guideline.

Effect of lubiprostone on vinca alkaloid-induced constipation in patients with hematological malignancies: a propensity score-matched analysis.

Patients receiving vinca alkaloids for hematological malignancies frequently experience constipation that is unresponsive to laxatives. Research on treatment of vinca alkaloid-induced constipation is limited. This study aimed to determine whether the chloride channel activator lubiprostone ameliorates vinca alkaloid-induced constipation in patients with hematological malignancies. In this retrospective cohort study, vinca alkaloid-induced constipation (grade ≥ 3 using the Common Terminology Criteria for Adverse Events) was investigated in patients treated for hematological malignancies between July 2014 and June 2019 who had already been prescribed osmotic laxatives and additionally received either a stimulant laxative or lubiprostone. Univariate and multivariate analyses were performed to identify the risk factors for persistent constipation after introduction of the second laxative. A propensity score model was used to match 67 patients taking a stimulant laxative and 67 treated with lubiprostone, and the occurrence of intractable constipation was compared between groups. Overall, 203 patients were included, among whom 50 (25%) had constipation. On multivariate analysis, body mass index, opioid use, and addition of lubiprostone were independently associated with constipation. Patients treated with lubiprostone were significantly less likely to experience intractable constipation than did those treated with stimulant laxatives (10% vs. 34%, P = 0.002). Moreover, post-constipation diarrhea was significantly less frequent among patients treated with lubiprostone (42% vs. 63%, P = 0.024). Lubiprostone was more effective than stimulant laxatives at treating vinca alkaloid-induced intractable constipation in patients with hematological malignancies, and its use could enable safe vinca alkaloid chemotherapy.

Ivacaftor Reverses Airway Mucus Abnormalities in a Rat Model Harboring a Humanized G551D-CFTR.

Rationale: Animal models have been highly informative for understanding the characteristics, onset, and progression of cystic fibrosis (CF) lung disease. In particular, the CFTR-/- rat has revealed insights into the airway mucus defect characteristic of CF but does not replicate a human-relevant CFTR (cystic fibrosis transmembrane conductance regulator) variant.Objectives: We hypothesized that a rat expressing a humanized version of CFTR and harboring the ivacaftor-sensitive variant G551D could be used to test the impact of CFTR modulators on pathophysiologic development and correction.Methods: In this study, we describe a humanized-CFTR rat expressing the G551D variant obtained by zinc finger nuclease editing of a human complementary DNA superexon, spanning exon 2-27, with a 5' insertion site into the rat gene just beyond intron 1. This targeted insertion takes advantage of the endogenous rat promoter, resulting in appropriate expression compared with wild-type animals.Measurements and Main Results: The bioelectric phenotype of the epithelia recapitulates the expected absence of CFTR activity, which was restored with ivacaftor. Large airway defects, including depleted airway surface liquid and periciliary layers, delayed mucus transport rates, and increased mucus viscosity, were normalized after the administration of ivacaftor.Conclusions: This model is useful to understand the mechanisms of disease and the extent of pathology reversal with CFTR modulators.

Management of functional constipation in children and adults.

Functional constipation is common in children and adults worldwide. Functional constipation shows similarities in children and adults, but important differences also exist regarding epidemiology, symptomatology, pathophysiology, diagnostic workup and therapeutic management. In children, the approach focuses on the behavioural nature of the disorder and the initial therapeutic steps involve toilet training and laxatives. In adults, management focuses on excluding an underlying cause and differentiating between different subtypes of functional constipation - normal transit, slow transit or an evacuation disorder - which has important therapeutic consequences. Treatment of adult functional constipation involves lifestyle interventions, pelvic floor interventions (in the presence of a rectal evacuation disorder) and pharmacological therapy. When conventional treatments fail, children and adults are considered to have intractable functional constipation, a troublesome and distressing condition. Intractable constipation is managed with a stepwise approach and in rare cases requires surgical interventions such as antegrade continence enemas in children or colectomy procedures for adults. New drugs, including prokinetic and prosecretory agents, and surgical strategies, such as sacral nerve stimulation, have the potential to improve the management of children and adults with intractable functional constipation.

Italian and North American dietary intake after ivacaftor treatment for Cystic Fibrosis Gating Mutations.

BACKGROUND: In patients with cystic fibrosis (CF), ivacaftor treatment results in significant weight gain and the impact on diet has not been explored. METHODS: A study in 22 subjects (6.1-61.6 years) compared diet, energy balance, weight gain, and body composition, before and after three months of treatment in Italians and North Americans with CFTR gating mutations. RESULTS: With no differences between groups in energy or macronutrient intake at baseline, fat intake increased in all subjects, and both fat and energy intake increased in Italians. Height, weight, BMI, lean and fat mass, and % body fat increased and resting energy expenditure decreased after treatment. Weight gain was associated with energy and fat intake. CONCLUSIONS: Fat intake increased with treatment, possibly due to the recommendation to take ivacaftor with high fat meals. Increased energy and fat intake correlated with weight gain. Regional dietary patterns differed.

Childhood constipation: finally something is moving!

Recent developments in the evaluation and treatment of childhood constipation are likely to influence the way we deal with pediatric defecation disorders in the near future. Innovations in both colonic and anorectal manometry are leading to novel insights into functional defecation disorders in children. Promising results have been achieved with innovative therapies such as electrical stimulation and new drugs with targets that differ from conventional pharmacological treatments. Also, new surgical approaches, guided by manometric findings, have led to improvement in patient outcome. Finally, utilization of non-pharmacological interventions such as fiber and probiotics has been a field of particular interest in recent years. The aim of this article is to provide an update on these and other novel diagnostic and therapeutic tools related to childhood constipation.

Alteration of the Intestinal Environment by Lubiprostone Is Associated with Amelioration of Adenine-Induced CKD.

The accumulation of uremic toxins is involved in the progression of CKD. Various uremic toxins are derived from gut microbiota, and an imbalance of gut microbiota or dysbiosis is related to renal failure. However, the pathophysiologic mechanisms underlying the relationship between the gut microbiota and renal failure are still obscure. Using an adenine-induced renal failure mouse model, we evaluated the effects of the ClC-2 chloride channel activator lubiprostone (commonly used for the treatment of constipation) on CKD. Oral administration of lubiprostone (500 µg/kg per day) changed the fecal and intestinal properties in mice with renal failure. Additionally, lubiprostone treatment reduced the elevated BUN and protected against tubulointerstitial damage, renal fibrosis, and inflammation. Gut microbiome analysis of 16S rRNA genes in the renal failure mice showed that lubiprostone treatment altered their microbial composition, especially the recovery of the levels of the Lactobacillaceae family and Prevotella genus, which were significantly reduced in the renal failure mice. Furthermore, capillary electrophoresis-mass spectrometry-based metabolome analysis showed that lubiprostone treatment decreased the plasma level of uremic toxins, such as indoxyl sulfate and hippurate, which are derived from gut microbiota, and a more recently discovered uremic toxin, trans-aconitate. These results suggest that lubiprostone ameliorates the progression of CKD and the accumulation of uremic toxins by improving the gut microbiota and intestinal environment.