Pre- versus post-operative untargeted plasma nuclear magnetic resonance spectroscopy metabolomics of pheochromocytoma and paraganglioma

Abstract

Purpose Pheochromocytomas and Paragangliomas (PPGL) result in chronic catecholamine excess and serious health complications. A recent study obtained a metabolic signature in plasma from PPGL patients; however, its targeted nature may have generated an incomplete picture and a broader approach could provide additional insights. We aimed to characterize the plasma metabolome of PPGL patients before and after surgery, using an untargeted approach, and to broaden the scope of the investigated metabolic impact of these tumors. Design A cohort of 36 PPGL patients was investigated. Blood plasma samples were collected before and after surgical tumor removal, in association with clinical and tumor characteristics. Methods Plasma samples were analyzed using untargeted nuclear magnetic resonance (NMR) spectroscopy metabolomics. The data were evaluated using a combination of uni- and multi-variate statistical methods. Results Before surgery, patients with a nonadrenergic tumor could be distinguished from those with an adrenergic tumor based on their metabolic profiles. Tyrosine levels were significantly higher in patients with high compared to those with low BMI. Comparing subgroups of pre-operative samples with their post-operative counterparts, we found a metabolic signature that included ketone bodies, glucose, organic acids, methanol, dimethyl sulfone and amino acids. Three signals with unclear identities were found to be affected. Conclusions Our study suggests that the pathways of glucose and ketone body homeostasis are affected in PPGL patients. BMI-related metabolite levels were also found to be altered, potentially linking muscle atrophy to PPGL. At baseline, patient metabolomes could be discriminated based on their catecholamine phenotype.

Preanalytical Pitfalls in Untargeted Plasma Nuclear Magnetic Resonance Metabolomics of Endocrine Hypertension

“…Glutamate was included in a panel for detecting albuminuria in hypertensive patients [33] and, along with proline, has shown a statistically different concentration distribution in hypertensive nephrosclerosis compared to controls [34]. In our previous work [35], proline and methanol were found to be higher in preoperative PPGL patients. To investigate possible confounders in our EHT-PHT signatures, we employed three correction approaches to compare results.…”

“…We analyzed Lithium Heparin blood plasma samples collected from 356 patients sampled at 13 ENSAT-HT centers, along with the post-operative counterparts of a subset of PPGL samples, which were used in our previous study [ 35 ]. After excluding technical outliers, 337 patients were finally included.…”

“…We recorded spectra according to our NMR method as reported and previously applied [ 35 , 55 ]. Study samples, along with 146 Quality Control (QC) samples, were analyzed over 46 batches, whereas 99 Healthy Volunteer (HV) samples, were analyzed over 43 batches.…”

“…Both the sequence and batch number of all samples were recorded for estimating technical variability. Longitudinal Eddy-Current Delay (LED) spectra were recorded and processed as previously described [ 35 , 55 ]. Spectra with high line width were not used for further analysis (maleic acid peak width > 1.2 Hz, n = 4), along with spectra recorded from samples that had large chemical shift differences from other samples ( n = 4) or peaks corresponding to EDTA ( n = 2) or citrate (intensities corresponding to blood collection, n = 1).…”