IMMUNOLOGIC AND BIOCHEMICAL COMPARISON OF URINARY GLYCOPROTEINS IN PATIENTS WITH CYSTIC FIBROSIS OF THE PANCREAS AND NORMAL CONTROLS

Urinary metabolomics reveals unique metabolic signatures in infants with cystic fibrosis

BACKGROUND

Biologic pathways and metabolic mechanisms underpinning early systemic disease in cystic fibrosis (CF) are poorly understood. The Baby Observational and Nutrition Study (BONUS) was a prospective multi-center study of infants with CF with a primary aim to examine the current state of nutrition in the first year of life. Its secondary aim was to prospectively explore concurrent nutritional, metabolic, respiratory, infectious, and inflammatory characteristics associated with early CF anthropometric measurements. We report here metabolomics differences within the urine of these infants as compared to infants without CF.

METHODS

Urine metabolomics was performed for 85 infants with predefined clinical phenotypes at approximately one year of age enrolled in BONUS via Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS). Samples were stratified by disease status (non-CF controls (n = 22); CF (n = 63, All-CF)) and CF clinical phenotype: respiratory hospitalization (CF Resp, n = 22), low length (CF LL, n = 23), and low weight (CF LW, n = 15).

RESULTS

Global urine metabolomics profiles in CF were heterogeneous, however there were distinct metabolic differences between the CF and non-CF groups. Top pathways altered in CF included tRNA charging and methionine degradation. ADCYAP1 and huntingtin were identified as predicted unique regulators of altered metabolic pathways in CF compared to non-CF. Infants with CF displayed alterations in metabolites associated with bile acid homeostasis, pentose sugars, and vitamins.

CONCLUSIONS

Predicted metabolic pathways and regulators were identified in CF infants compared to non-CF, but metabolic profiles were unable to discriminate between CF phenotypes. Targeted metabolomics provides an opportunity for further understanding of early CF disease.

TRIAL REGISTRATION

United States ClinicalTrials.Gov registry NCT01424696 (clinicaltrials.gov).

Analysis and HPLC fractionation of urine from patients with cystic fibrosis, chronic lung diseases and normal controls

The amounts of creatinine, protein, carbohydrate and sialic acid in the urine of 19 patients with cystic fibrosis (CF), 12 normal controls and 11 pathological controls with chronic lung disease have been determined. The mean creatinine excretion levels of the total CF group as well as the CF subgroups are significantly decreased when compared to normal controls but comparable to pathological controls. Mean urinary protein levels appear to be increased in patients with CF compared to normal controls and pathological controls but the increased levels resulted from factors (e.g., presence of diabetes mellitus) other than CF. No significant differences were found in amounts of total carbohydrate and sialic acid in urine and fractionated urinary preparations for the total group of nondiabetic patients with CF when compared to both normal and pathological controls. HPLC fractionation of low Mr (less than 10,000 Daltons) urinary preparations indicated the presence of an unknown peak in all of the antibiotic-treated CF patients, 43% of CF patients on low or no medication, 17% of the normal controls and 9% of the pathological controls. The present results illustrate the importance of including appropriate pathological controls and dividing patients with CF into subgroups according to clinical factors and types of therapy employed.