Normalization of sweat chloride concentration and clinical improvement with ivacaftor in a patient with cystic fibrosis with mutation S549N.
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ABSTRACT:
SUBMITTER: McGarry ME
PROVIDER: S-EPMC4502741 | biostudies-other | 2013 Oct
REPOSITORIES: biostudies-other
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Project description:The sweat chloride test remains the gold standard for confirmatory diagnosis of cystic fibrosis (CF) in support of universal newborn screening programs. However, it provides ambiguous results for intermediate sweat chloride cases while not reflecting disease progression when classifying the complex CF disease spectrum given the pleiotropic effects of gene modifiers and environment. Herein we report the first characterization of the sweat metabolome from screen-positive CF infants and identify metabolites associated with disease status that complement sweat chloride testing. Pilocarpine-stimulated sweat specimens were collected independently from two CF clinics, including 50 unaffected infants (e.g., carriers) and 18 confirmed CF cases. Nontargeted metabolite profiling was performed using multisegment injection-capillary electrophoresis-mass spectrometry as a high throughput platform for analysis of polar/ionic metabolites in volume-restricted sweat samples. Amino acids, organic acids, amino acid derivatives, dipeptides, purine derivatives, and unknown exogenous compounds were identified in sweat when using high resolution tandem mass spectrometry, including metabolites associated with affected yet asymptomatic CF infants, such as asparagine and glutamine. Unexpectedly, a metabolite of pilocarpine, used to stimulate sweat secretion, pilocarpic acid, and a plasticizer metabolite from environmental exposure, mono(2-ethylhexyl)phthalic acid, were secreted in the sweat of CF infants at significantly lower concentrations relative to unaffected CF screen-positive controls. These results indicated a deficiency in human paraoxonase, an enzyme unrelated to mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) and impaired chloride transport, which is a nonspecific arylesterase/lactonase known to mediate inflammation, bacterial biofilm formation, and recurrent lung infections in affected CF children later in life. This work sheds new light into the underlying mechanisms of CF pathophysiology as required for new advances in precision medicine of orphan diseases that benefit from early detection and intervention, including new molecular targets for therapeutic intervention.
| S-EPMC5571457 | biostudies-literature
Project description:The current guidelines for sweat chloride analysis identify the procedures for sweat collection, but not for chloride assay, which is usually performed by methods originally not aiming at the low concentrations of chloride found in sweat. To overcome this limitation, we set up, characterized, and adopted an original inductively coupled plasma mass spectrometry (ICP-MS) method for sweat chloride determination, which was designed for its easy use in a clinical laboratory. The method was linear in the range 8.5E-3 to 272.0E-3 mM, precision exhibited a relative standard deviation <?6%, and accuracy was in the range 99.7-103.8%. Limit of blank, limit of detection, and limit of quantitation were 2.1 mM, 3.2 mM, and 7.0 mM, respectively, which correspond to real concentrations injected into the mass spectrometer of 3.9E-3 mM for LOD and 8.5E-3 mM for LOQ. At first, the method was tested on 50 healthy volunteers who exhibited a mean chloride concentration of 15.7 mM (25-75th percentile 10.1-19.3 mM, range 2.8-37.4 mM); then, it was used to investigate two patients with suspected cystic fibrosis, who exhibited sweat chloride values of 65.6 mM and 81.2 mM, respectively. Moreover, the method was cross-validated by assaying 50 samples with chloride concentration values in the range 10-131 mM, by both ICP-MS and coulometric titration, which is the technology officially used in Tuscany for cystic fibrosis newborn screening. The reference analytical performances and the relatively low cost of ICP-MS, accompanied by the advantageous cost of a single sweat chloride assay, make this technology the best candidate to provide a top reference method for the quantification of chloride in sweat. The method that we propose was optimized and validated for sweat samples ??75 mg, which is the minimum amount requested by the international protocols. However, the method sensitivity and, in addition, the possibility to reduce the sample dilution factor, make possible the quantification of chloride even in samples weighting <?75 mg that are discarded according to the current guidelines. Graphical abstract.
| S-EPMC7495987 | biostudies-literature
Project description:BACKGROUND:Disruption of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function causes cystic fibrosis (CF), and lung disease produces most of the mortality. Loss of CFTR-mediated HCO3- secretion reduces the pH of airway surface liquid (ASL) in vitro and in neonatal humans and pigs in vivo. However, we previously found that, in older children and adults, ASL pH does not differ between CF and non-CF. Here, we tested whether the pH of CF ASL increases with time after birth. Finding that it did suggested that adaptations by CF airways increase ASL pH. This conjecture predicted that increasing CFTR activity in CF airways would further increase ASL pH and also that increasing CFTR activity would correlate with increases in ASL pH. METHODS:To test for longitudinal changes, we measured ASL pH in newborns and then at 3-month intervals. We also studied people with CF (bearing G551D or R117H mutations), in whom we could acutely stimulate CFTR activity with ivacaftor. To gauge changes in CFTR activity, we measured changes in sweat Cl- concentration immediately before and 48 hours after starting ivacaftor. RESULTS:Compared with that in the newborn period, ASL pH increased by 6 months of age. In people with CF bearing G551D or R117H mutations, ivacaftor did not change the average ASL pH; however reductions in sweat Cl- concentration correlated with elevations of ASL pH. Reductions in sweat Cl- concentration also correlated with improvements in pulmonary function. CONCLUSIONS:Our results suggest that CFTR-independent mechanisms increase ASL pH in people with CF. We speculate that CF airway disease, which begins soon after birth, is responsible for the adaptation. FUNDING:Vertex Inc., the NIH (P30DK089507, 1K08HL135433, HL091842, HL136813, K24HL102246), the Cystic Fibrosis Foundation (SINGH17A0 and SINGH15R0), and the Burroughs Wellcome Fund.
| S-EPMC6129116 | biostudies-literature
Project description:Newborn screening (NBS) for cystic fibrosis (CF) has become standard practice in many countries. Consequently, the prevalence of infants with intermediate sweat test results has increased. This study examined clinical practices in the United States (US) related to intermediate sweat test results subsequent to NBS.Respondents from 77 (47% response rate) US CF centers completed telephone surveys documenting clinical practices related to intermediate sweat chloride levels (30-59 mmol/L) following abnormal NBS.Thirty percent of centers followed CF Foundation guidelines for classifying intermediate results. There was much variability in sweat testing procedures, diagnostic labels, additional diagnostics, addressing prognosis, and services offered to parents. CF center staff identified a need for resources to better address the uncertainty associated with intermediate results.Results suggest the need for education regarding current guidelines and consensus regarding the nomenclature and services offered to families of newborns with intermediate sweat test results.
| S-EPMC3616645 | biostudies-literature
Project description:Sweat plays a crucial role in thermo-regulation and skin health and potentially antimicrobial defense. Its composition is highly dynamic and its homeostasis involves a fine tuning of metabolic pathways. In-depth profiling of sweat protein composition will increase our understanding of skin disorders. Cystic Fibrosis (CF) is associated with high NaCl sweat concentration due to the absence of the CFTR protein. Patients with CF (pwCF) often display aquagenic palmoplantar keratodermia, a rare skin disorder characterized by skin wrinkling with oedema and whitish papules on the palms and/or soles, the pathophysiology of which is unknown. We report an in-depth analysis of the human sweat proteome of pwCF patients in comparison with that of healthy subjects (S).
2023-03-11 | PXD032894 | Pride
Project description:(1) Background: Diagnostic testing for cystic fibrosis (CF) is based on a sweat chloride test (SCT) considering the appropriate signs and symptoms of the disease and results of a gene mutation analysis. In 2014, the Istituto Superiore di Sanità (ISS) established a pilot Italian external quality assessment program for CF SCT (Italian EQA-SCT), which is now a third party service carried out by the ISS. (2) Methods: The ongoing scheme is prospective, enrollment is voluntary, and the payment of a fee is required. Results are shared through a dedicated web-facility. Assessment covers the analysis, interpretation, and reporting of results. (3) Results: Thirteen, fifteen, sixteen, and fifteen different laboratories, respectively, participated from 2015 to 2016 and from 2018 to 2019 in the Italian EQA-SCT scheme. Eleven different laboratories participated each year in all four rounds of the Italian EQA-SCT. (4) Conclusions: The overall results obtained from the laboratories participating constantly clearly show that their qualitative and quantitative performance improved significantly. This is due to the opportunity-after receiving the EQA results-to constantly review their performance and address any inconsistencies. We firmly believe that participation in the EQA program will improve the quality of participating laboratories and that EQA participation should become mandatory as a fundamental requirement for laboratory accreditation.
| S-EPMC7246827 | biostudies-literature
Project description:Metabolic alkalosis is uncommon in infancy. Cystic fibrosis (CF) patients can develop dehydration because of sweat salt or gastrointestinal losses; with the correct salt supplementation, the electrolyte alterations can be reversed. Here, we present a CF patient with recurrent metabolic alkalosis, initially oriented as pseudo-Bartter's syndrome. However, despite accurate treatment, patient needed daily intravenous fluids to maintain homeostasis. An extended study was made, including a urine study that could rule out Bartter's diagnosis. Finally, after a complementary test that included electrolyte stools study and genetic analysis, congenital chloride diarrhea could be diagnosed.
| S-EPMC6976311 | biostudies-literature
Project description:The concentration of chloride in sweat remains the most robust biomarker for confirmatory diagnosis of cystic fibrosis (CF), a common life-shortening genetic disorder. Early diagnosis via quantitative assessment of sweat chloride allows prompt initiation of care and is critically important to extend life expectancy and improve quality of life. The collection and analysis of sweat using conventional wrist-strapped devices and iontophoresis can be cumbersome, particularly for infants with fragile skin, who often have insufficient sweat production. Here, we introduce a soft, epidermal microfluidic device ("sweat sticker") designed for the simple and rapid collection and analysis of sweat. Intimate, conformal coupling with the skin supports nearly perfect efficiency in sweat collection without leakage. Real-time image analysis of chloride reagents allows for quantitative assessment of chloride concentrations using a smartphone camera, without requiring extraction of sweat or external analysis. Clinical validation studies involving patients with CF and healthy subjects, across a spectrum of age groups, support clinical equivalence compared to existing device platforms in terms of accuracy and demonstrate meaningful reductions in rates of leakage. The wearable microfluidic technologies and smartphone-based analytics reported here establish the foundation for diagnosis of CF outside of clinical settings.
| S-EPMC8351625 | biostudies-literature
Project description:In clinical routine, the diagnosis of cystic fibrosis (CF) is still a challenge due to the limitations of diagnosis guidelines and tests. A diagnosis test of choice, the sweat test measures eccrine sweat chloride concentration as a byproduct of the eccrine sweat gland CFTR function. Despite the combined use of CFTR genotyping and direct physiologic testing of CFTR function, reports of inconclusive diagnosis justified the need for alternative tests and new biomarkers. Meanwhile, eccrine sweat composition has already been linked to disease-specific profiles of non-electrolytes (i.e. proteins, peptides and metabolites). In this study, we analyzed sweat samples from 28 healthy volunteers and 14 CF patients by UHPLC-Q-Orbitrap-based Shotgun proteomics, to address CF-related changes in sweat protein composition and abundance. Over 1000 proteins were identified and quantified in a label-free manner. Beside similar protein composition, enrichment and functional classifications, HV and CF samples were grouped apart since protein abundance profiles were significantly correlated with CF status and degree of severity (ΔF508 homozygous and pancreatic insufficiency onset). Four-hundred and two proteins in CF-specific abundance, 68 proteins in genotype-specific abundance and 71 proteins in abundance related to pancreatic status, respectively, highlighted eccrine gland cell perturbations in protein biosynthesis & trafficking, CFTR proteostasis & membrane stability, cell-cell adherence, membrane integrity & cytoskeleton crosstalk. Cytoskeleton-related biomarkers were of utmost interest because of consistent abundances between CF sweat and other CF tissues. Nine clinical CF diagnosis biomarker (CUTA, ARG1, EZR, AGA, FLNA, MAN1A1, MIA3, LFNG, SIAE) and 5 CF severity biomarker (ARG1, GPT, MDH2, EML4 (ΔF508 homozygous), MGAT1 (pancreatic insufficiency)) candidates were deemed suitable for further verification.
2022-10-13 | PXD028518 | Pride
Project description:BackgroundCystic Fibrosis (CF) is a multi-systemic disease resulting from mutations in the Cystic Fibrosis Transmembrane Regulator (CFTR) gene and has major manifestations in the sino-pulmonary, and gastro-intestinal tracts. Clinical phenotypes were generated using 26 common clinical variables to generate classes that overlapped quantiles of lung function and were based on multiple aspects of CF systemic disease.MethodsThe variables included age, gender, CFTR mutations, FEV1% predicted, FVC% predicted, height, weight, Brasfield chest xray score, pancreatic sufficiency status and clinical microbiology results. Complete datasets were compiled on 211 subjects. Phenotypes were identified using a proximity matrix generated by the unsupervised Random Forests algorithm and subsequent clustering by the Partitioning around Medoids (PAM) algorithm. The final phenotypic classes were then characterized and compared to a similar dataset obtained three years earlier.FindingsClinical phenotypes were identified using a clustering strategy that generated four and five phenotypes. Each strategy identified 1) a low lung health scores phenotype, 2) a younger, well-nourished, male-dominated class, 3) various high lung health score phenotypes that varied in terms of age, gender and nutritional status. This multidimensional clinical phenotyping strategy identified classes with expected microbiology results and low risk clinical phenotypes with pancreatic sufficiency.InterpretationThis study demonstrated regional adult CF clinical phenotypes using non-parametric, continuous, ordinal and categorical data with a minimal amount of subjective data to identify clinically relevant phenotypes. These studies identified the relative stability of the phenotypes, demonstrated specific phenotypes consistent with published findings and identified others needing further study.
| S-EPMC4378917 | biostudies-literature