Gilbert's syndrome leads to elevated bilirubin after initiation of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis.

Nine people with cystic fibrosis (pwCF) were found to have isolated elevations in serum total bilirubin after starting elexacaftor/tezacaftor/ivacaftor (ETI) that were associated with Gilbert's Syndrome. In longitudinal examination, total bilirubin levels increased substantially after initiation of ETI without elevations in liver transaminases in those with this syndrome. Because elevated bilirubin levels in Gilbert's Syndrome are benign, ETI was able to be continued in these individuals. Genetic testing for this relatively common syndrome should be strongly considered for pwCF experiencing isolated hyperbilirubinemia after starting ETI, since appropriate diagnosis may help pwCF avoid unnecessary interruption in this therapy with significant health benefits in CF.

Gut Microbial Changes Following Fecal Microbiota Transplantation for D-Lactic Acidosis in Two Children.

D-lactic acidosis (D-LA) is an uncommon complication of short bowel syndrome characterized by elevated plasma D-lactate and encephalopathy. Treatments include rehydration, dietary carbohydrate restriction, and antibiotics to alter the gut microbiota. Fecal microbiota transplantation (FMT) has recently been used in children to successfully treat D-LA. We compared the clinical course and then utilized metagenomic shotgun sequencing to describe changes in the composition and function of the intestinal microbiome following FMT in 2 patients with recurrent D-LA. FMT altered the composition of the fecal microbiota in these 2 patients with recurrent D-LA, though not necessarily in a consistent manner. Importantly, microbial metabolic pathways were also impacted by FMT, which may be critical for achieving desired clinical outcomes. While sample size limits the generalizability of our results, these findings set the stage for further understanding of the role of microbes in the pathogenesis of recurrent D-LA.

Prevalence, Risk Factors, and Sequelae of Asymptomatic Clostridioides difficile Colonization in Children with Cystic Fibrosis.

Patients with CF (pwCF) have high antibiotic use and an altered intestinal microbiome, known risk factors for infection with Clostridioides difficile. However, in adults with CF, C. difficile infection (CDI) is uncommon and asymptomatic colonization with C. difficile occurs frequently, for reasons that remain unclear. We investigated the rate, risk factors, and sequelae of asymptomatic C. difficile colonization in children with CF (cwCF). We identified that 32% of cwCF were colonized with C. difficile without acute gastrointestinal symptoms. Higher BMI and exposure to specific antibiotic classes (cephalosporins, fluoroquinolones, and vancomycin) were significantly associated with C. difficile colonization. No children developed symptomatic CDI in 90-days following enrollment.

Reversible deficits in apical transporter trafficking associated with deficiency in diacylglycerol acyltransferase.

Deficiency in diacylglycerol acyltransferase (DGAT1) is a rare cause of neonatal diarrhea, without a known mechanism or in vitro model. A patient presenting at our institution at 7 weeks of life with failure to thrive and diarrhea was found by whole-exome sequencing to have a homozygous DGAT1 truncation mutation. Duodenal biopsies showed loss of DGAT1 and deficits in apical membrane transporters and junctional proteins in enterocytes. When placed on a very low-fat diet, the patient's diarrhea resolved with normalization of brush border transporter localization in endoscopic biopsies. DGAT1 knockdown in Caco2-BBe cells modeled the deficits in apical trafficking, with loss of apical DPPIV and junctional occludin. Elevation in cellular lipid levels, including diacylglycerol (DAG) and phospholipid metabolites of DAG, was documented by lipid analysis in DGAT1 knockdown cells. Culture of the DGAT1 knockdown cells in lipid-depleted media led to re-establishment of occludin and return of apical DPPIV. DGAT1 loss appears to elicit global changes in enterocyte polarized trafficking that could account for deficits in absorption seen in the patient. The in vitro modeling of this disease should allow for investigation of possible therapeutic targets.

Noninfectious Manifestations and Complications of Chronic Granulomatous Disease.

Chronic granulomatous disease (CGD), a primary immunodeficiency characterized by a deficient neutrophil oxidative burst and the inadequate killing of microbes, is well known to cause a significantly increased risk of invasive infection. However, infectious complications are not the sole manifestations of CGD; substantial additional morbidity is driven by noninfectious complications also. These complications can include, for example, a wide range of inflammatory diseases that affect the gastrointestinal tract, lung, skin, and genitourinary tract and overt autoimmune disease. These diseases can occur at any age and are especially problematic in adolescents and adults with CGD. Many of these noninfectious complications present a highly challenging therapeutic conundrum, wherein immunosuppression must be balanced against an already markedly increased risk of invasive fungal and bacterial infections. In this review, the myriad noninfectious complications of CGD are discussed, as are important gaps in our understanding of these processes, which warrant further investigation.

Elevated prostaglandin E metabolites and abnormal plasma fatty acids at baseline in pediatric cystic fibrosis patients: a pilot study.

BACKGROUND: Airway inflammation is a significant contributor to the morbidity of cystic fibrosis (CF) disease. One feature of this inflammation is the production of oxygenated metabolites, such as prostaglandins. Individuals with CF are known to have abnormal metabolism of fatty acids, typically resulting in reduced levels of linoleic acid (LA) and docosahexaenoic acid (DHA). METHODS: This is a randomized, double-blind, cross-over clinical trial of DHA supplementation with endpoints of plasma fatty acid levels and prostaglandin E metabolite (PGE-M) levels. Patients with CF age 6-18 years with pancreatic insufficiency were recruited. Each participant completed 3 four-week study periods: DHA at two different doses (high dose and low dose) and placebo with a minimum 4 week wash-out between each period. Blood, urine, and exhaled breath condensate (EBC) were collected at baseline and after each study period for measurement of plasma fatty acids as well as prostaglandin E metabolites. RESULTS: Seventeen participants were enrolled, and 12 participants completed all 3 study periods. Overall, DHA supplementation was well tolerated without significant adverse events. There was a significant increase in plasma DHA levels with supplementation, but no significant change in arachidonic acid (AA) or LA levels. However, at baseline, AA levels were lower and LA levels were higher than previously reported for individuals with CF. Urine PGE-M levels were elevated in the majority of participants at baseline, and while levels decreased with DHA supplementation, they also decreased with placebo. CONCLUSIONS: Urine PGE-M levels are elevated at baseline in this cohort of pediatric CF patients, but there was no significant change in these levels with DHA supplementation compared to placebo. In addition, baseline plasma fatty acid levels for this cohort showed some difference to prior reports, including higher levels of LA and lower levels of AA, which may reflect changes in clinical care, and consequently warrants further investigation.

Increased elongase 6 and Δ9-desaturase activity are associated with n-7 and n-9 fatty acid changes in cystic fibrosis.

Patients with cystic fibrosis, caused by mutations in CFTR, exhibit specific and consistent alterations in the levels of particular unsaturated fatty acids compared with healthy controls. Evidence suggests that these changes may play a role in the pathogenesis of this disease. Among these abnormalities are increases in the levels of n-7 and n-9 fatty acids, particularly palmitoleate (16:1n-7), oleate (18:1n-9), and eicosatrienoate or mead acid (20:3n-9). The underlying mechanisms of these particular changes are unknown, but similar changes in the n-3 and n-6 fatty acid families have been correlated with increased expression of fatty acid metabolic enzymes. This study demonstrated that cystic fibrosis cells in culture exhibit increased metabolism along the metabolic pathways leading to 16:1n-7, 18:1n-9, and 20:3n-9 compared with wild-type cells. Furthermore, these changes are accompanied by increased expression of the enzymes that produce these fatty acids, namely Δ5, Δ6, and Δ9 desaturases and elongases 5 and 6. Taken together, these findings suggest that fatty acid abnormalities of the n-7 and n-9 series in cystic fibrosis are as a result, at least in part, of increased expression and activity of these metabolic enzymes in CFTR-mutated cells.