Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study

Abstract:

Background: Around 10% of people who had COVID-9 infection suffer from persistent symptoms such as fatigue, dyspnoea, chest pain, arthralgia/myalgia, sleep disturbances, cognitive dysfunction and impairment of mental health. Different underlying pathomechanisms appear to be involved, in particular inflammation, alterations in amino acid metabolism, autonomic dysfunction and gut dysbiosis.

Aim: As routine tests are often inconspicuous in patients with Long COVID (LC), similarly to patients suffering from myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), accessible biomarkers indicating dysregulation of specific pathways are urgently needed to identify underlying pathomechanisms and enable personalized medicine treatment. Within this pilot study we aimed to proof traceability of altered metabolism by urine analysis.

Patients and methods: Urine metabolome analyses were performed to investigate the metabolic signature of patients with LC (n = 25; 20 women, 5 men) in comparison to healthy controls (Ctrl, n = 8; 7 women, 1 man) and individuals with ME/CFS (n = 8; 2 women, 6 men). Concentrations of neurotransmitter precursors tryptophan, phenylalanine and their downstream metabolites, as well as their association with symptoms (fatigue, anxiety and depression) in the patients were examined.

Results and conclusion: Phenylalanine levels were significantly lower in both the LC and ME/CFS patient groups when compared to the Ctrl group. In many LC patients, the concentrations of downstream metabolites of tryptophan and tyrosine, such as serotonin, dopamine and catecholamines, deviated from the reference ranges. Several symptoms (sleep disturbance, pain or autonomic dysfunction) were associated with certain metabolites. Patients experiencing fatigue had lower levels of kynurenine, phenylalanine and a reduced kynurenine to tryptophan ratio (Kyn/Trp). Lower concentrations of gamma-aminobutyric acid (GABA) and higher activity of kynurenine 3-monooxygenase (KMO) were observed in patients with anxiety.

Conclusively, our results suggest that amino acid metabolism and neurotransmitter synthesis is disturbed in patients with LC and ME/CFS. The identified metabolites and their associated dysregulations could serve as potential biomarkers for elucidating underlying pathomechanisms thus enabling personalized treatment strategies for these patient populations.

Source: Taenzer M, Löffler-Ragg J, Schroll A, Monfort-Lanzas P, Engl S, Weiss G, Brigo N, Kurz K. Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study. Int J Tryptophan Res. 2023 Dec 22;16:11786469231220781. doi: 10.1177/11786469231220781. PMID: 38144169; PMCID: PMC10748708. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10748708/ (Full text)

A laboratory approach for characterizing chronic fatigue: what does metabolomics tell us?

Abstract:

INTRODUCTION: Manifestations of fatigue range from chronic fatigue up to a severe syndrome and myalgic encephalomyelitis. Fatigue grossly affects the functional status and quality of life of affected individuals, prompting the World Health Organization to recognize it as a chronic non-communicable condition.

OBJECTIVES: Here, we explore the potential of urinary metabolite information to complement clinical criteria of fatigue, providing an avenue towards an objective measure of fatigue in patients presenting with the full spectrum of fatigue levels.

METHODS: The experimental group consisted of 578 chronic fatigue female patients. The measurement design was composed of (1) existing clinical fatigue scales, (2) a hepatic detoxification challenge test, and (3) untargeted proton nuclear magnetic resonance (1H-NMR) procedure to generate metabolomics data. Data analysed via an in-house Matlab script that combines functions from a Statistics and a PLS Toolbox.

RESULTS: Multivariate analysis of the original 459 profiled 1H-NMR bins for the low (control) and high (patient) fatigue groups indicated complete separation following the detoxification experimental challenge. Important bins identified from the 1H-NMR spectra provided quantitative metabolite information on the detoxification challenge for the fatigue groups.

CONCLUSIONS: Untargeted 1H-NMR metabolomics proved its applicability as a global profiling tool to reveal the impact of toxicological interventions in chronic fatigue patients. No clear potential biomarker emerged from this study, but the quantitative profile of the phase II biotransformation products provide a practical visible effect directing to up-regulation of crucial phase II enzyme systems in the high fatigue group in response to a high xenobiotic-load.

Source: Erasmus E, Mason S, van Reenen M, Steffens FE, Vorster BC, Reinecke CJ. A laboratory approach for characterizing chronic fatigue: what does metabolomics tell us? Metabolomics. 2019 Nov 27;15(12):158. doi: 10.1007/s11306-019-1620-4. https://www.ncbi.nlm.nih.gov/pubmed/31776682

Comparison of differential metabolites in urine of the middle school students with chronic fatigue syndrome before and after exercise

Abstract:

OBJECTIVE: To study the differential metabolites in urine and the characteristics of metabolic pathway of middle school students with chronic fatigue syndrome (CFS) before and after exercise, and then explain the metabolic mechanism of CFS.

METHODS: Eight male middle school students (age:17-19) with CFS were selected as the CFS group according to CFS screening criteria of the U.S. centers.At the same time, 8 male health students of the same age from the same school were selected as the control group. They were administrated to do one-time exercise on the improved Harvard step (up and down steps 30 times/min for 3 minutes). Their urine was collected before and after exercise, and the differential metabolites in urine were detected by liquid chromatography-mass spectrometry (LC-MS). The multidimensional statistical methods were used to analyze the metabolites by principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Finally, MetPA database was used to analyze the metabolites and to construct the correlative metabolic pathways.

RESULTS: Compared with the control group, the creatine, indoleacetaldehyde, phytosphingosine and pyroglutamic acid were selected as differential metabolites and the contents of those were decreased significantly (P<0.05 or P<0.01) in CFS group before the step movement. However, 11 differential metabolites in CFS group were selected out after exercise, which were nonanedioic acid, methyladenosine, acetylcarnitine, capric acid, corticosterone, creatine, levonorgestrel, pantothenic acid, pyroglutamic acid, xanthosine and xanthurenic acid in sequence, the contents of methyladenosine and creatine were significantly increased (P<0.05) and the contents of the other 9 differential metabolites were significantly decreased (P<0.05 or P<0.01)compared with the control group.

The 15 differential metabolites mentioned above were input MetPA database in order to analyze the metabolic pathways weighted score.The results showed that the arginine-proline metabolism pathway disorders were detected in the CFS group before exercise, the marker metabolite was creatine. And 3 metabolic pathways disorder were detected in the CFS group after exercise, which were arginine-proline metabolism, biosynthesis of pantothenic acid and CoA, steroid hormone biosynthesis, and the marker metabolites, in turn, were creatine, pantothenic acid and corticosterone.

CONCLUSIONS: The disorder of arginine-proline metabolic pathway is detected in CFS middle school students before exercise intervention. After exercise, it can be detected that the steroid hormone biosynthetic metabolic pathway, pantothenic acid and CoA metabolic pathways also have metabolic disorders.

Source: Chi AP, Wang ZN, Shi B, Yang XF, Min RX, Song J. Comparison of differential metabolites in urine of the middle school students with chronic fatigue syndrome before and after exercise. [Article in Chinese] Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2018 Apr 8;34(4):340-344 349. doi: 10.12047/j.cjap.5633.2018.078.  https://www.ncbi.nlm.nih.gov/pubmed/30788942

Hematologic and urinary excretion anomalies in patients with chronic fatigue syndrome

Abstract:

Patients with chronic fatigue syndrome (CFS) have a broad and variable spectrum of signs and symptoms with variable onsets. This report outlines the results of a single-blind, cross-sectional research project that extensively investigated a large cohort of 100 CFS patients and 82 non fatigued control subjects with the aim of performing a case-control evaluation of alterations in standard blood parameters and urinary amino and organic acid excretion profiles.

Blood biochemistry and full blood counts were unremarkable and fell within normal laboratory ranges. However, the case-control comparison of the blood cell data revealed that CFS patients had a significant decrease in red cell distribution width and increases in mean platelet volume, neutrophil counts, and the neutrophil-lymphocyte ratio.

Evaluation of the urine excretion parameters also revealed a number of anomalies. The overnight urine output and rate of amino acid excretion were both reduced in the CFS group (P < 0.01). Significant decreases in the urinary excretion of asparagine (P < 0.0001), phenylalanine (P < 0.003), the branch chain amino acids (P < 0.005), and succinic acid (P < 0.0001), as well as increases in 3-methylhistidine (P < 0.05) and tyrosine (P < 0.05) were observed.

It was concluded that the urinary excretion and blood parameters data supported the hypothesis that alterations in physiologic homeostasis exist in CFS patients.

 

Source: Niblett SH, King KE, Dunstan RH, Clifton-Bligh P, Hoskin LA, Roberts TK, Fulcher GR, McGregor NR, Dunsmore JC, Butt HL, Klineberg I, Rothkirch TB. Hematologic and urinary excretion anomalies in patients with chronic fatigue syndrome. Exp Biol Med (Maywood). 2007 Sep;232(8):1041-9. https://www.ncbi.nlm.nih.gov/pubmed/17720950

 

CFSUM1 and CFSUM2 in urine from patients with chronic fatigue syndrome are methodological artefacts

Abstract:

McGregor et al. reported increased levels of an unidentified urinary compound (CFSUM1) in patients with chronic fatigue syndrome (CFS), with reduced excretion of another unidentified compound (CFSUM2), and suggested the possibility of chemical or metabolic ‘markers’ for CFS. The identity of CFSUM1 as reported was erroneous and the identities of these compounds have remained unknown until now.

Urine samples were obtained from 30 patients with ME/CFS, 30 age- and sex-matched healthy controls, 20 control patients with depression and 22 control patients with rheumatoid arthritis. Samples were prepared using the published methods of McGregor et al. to produce heptafluorobutyryl-isobutyl derivatives of urinary metabolites. Alternative preparations utilised isopropyl, n-butyl and trifluoroacetyl derivatives. These were separated and identified using gas chromatography-mass spectrometry.

CFSUM2 was identified as being partially derivatised [isobutyl ester-mono-heptafluorobutyryl (HFB)] serine. CFSUM1 was identified as partially derivatised pyroglutamic acid, being the isobutyl ester without formation of a HFB derivative.

Both CFSUM1 and CFSUM2 are artefacts of the sample preparation procedure and previously reported quantitative abnormalities of CFSUM1 and CFSUM2 in urine from patients with ME/CFS are also artefactual. Pyroglutamic acid may be of primarily dietary origin. The methods used cannot provide reliable qualitative or quantitative data on urinary metabolites. No clinical or biochemical significance can be drawn between these compounds in ME/CFS or any other clinical conditions.

 

Source: Chalmers RA, Jones MG, Goodwin CS, Amjad S. CFSUM1 and CFSUM2 in urine from patients with chronic fatigue syndrome are methodological artefacts. Clin Chim Acta. 2006 Feb;364(1-2):148-58. Epub 2005 Aug 10. http://www.ncbi.nlm.nih.gov/pubmed/16095585

 

Urinary electrophoretic profiles from chronic fatigue syndrome and chronic fatigue syndrome/fibromyalgia patients: a pilot study for achieving their normalization

Abstract:

Aim of our study was to determine if there were distinct, disease-related patterns of urinary analytes in chronic fatigue syndrome (CFS) and chronic fatigue syndrome/fibromyalgia (CFS/FM) compared to normal controls (NC).

Urine was collected from these subjects for two consecutive 24 h periods and aliquots were submitted to micellar electrokinetic chromatography (MEKC). To compensate for the differences in peak migration times, these were normalized from the 35 min duration of run to a 100-point scale, and each peak was assigned its normalized time measure. Peak heights were also normalized by dividing the mAU by that of the internal standard (creatinine) and multiplying by 100. MEKC with normalization for peak height and migration time generated comparable results within each of the patient groups.

CFS/FM and CFS had significant differences in peaks compared to NC that may be of significance as biomarkers of illnesses.

 

Source: Casado B, Zanone C, Annovazzi L, Iadarola P, Whalen G, Baraniuk JN. Urinary electrophoretic profiles from chronic fatigue syndrome and chronic fatigue syndrome/fibromyalgia patients: a pilot study for achieving their normalization. J Chromatogr B Analyt Technol Biomed Life Sci. 2005 Jan 5;814(1):43-51. http://www.ncbi.nlm.nih.gov/pubmed/15607706

 

Preliminary determination of the association between symptom expression and urinary metabolites in subjects with chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) patients have a urinary metabolite labeled CFSUM1 with increased incidence (P < 0.004) and relative abundance (P < 0.00003). The relative abundances of urinary CFSUM1 and beta-alanine were associated with alterations in metabolite excretion and symptom incidence.

In 20 CFS patients and 45 non-CFS subjects, symptom/metabolite associations were investigated by assessing symptom sensitivity and specificity, and symptom indices of total symptom incidence, CFS core symptoms, cognitive, neurological, musculoskeletal, gastrointestinal, infection-related and genitourinary symptom indices, as well as a visual analogue pain scale of average pain intensity. Thirty-three symptoms had significant (P < 0.005) sensitivity and specificity in the CFS patients compared to that in the non-CFS controls.

Severe fatigue was the only symptom with 100% sensitivity and specificity and CFSUM1 excretion was the primary metabolite for expression of this symptom. All nine symptom indices had elevated responses in the CFS patients (all P < 0.0000001). Multiple regression analyses indicated that all the symptom indices had significant correlations (R) with changes in the urinary excretion of metabolites (P < 0.0001).

CFSUM1 and beta-alanine were the first and second metabolites correlated with the CFS core symptom index and CFSUM1 was primarily associated with infection-related and musculoskeletal indices whereas beta-alanine was primarily associated with gastrointestinal and genitourinary indices. The strong associations of CFSUM1 and beta-alanine with CFS symptom expression provide a molecular basis for developing an objective test for CFS.

 

Source: McGregor NR, Dunstan RH, Zerbes M, Butt HL, Roberts TK, Klineberg IJ. Preliminary determination of the association between symptom expression and urinary metabolites in subjects with chronic fatigue syndrome. Biochem Mol Med. 1996 Jun;58(1):85-92. http://www.ncbi.nlm.nih.gov/pubmed/8809350

 

Preliminary determination of a molecular basis of chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS/ME) is a debilitating fatigue illness that has an unknown etiology. We studied 20 chronic fatigue syndrome (CFS) patients, who complied with the Oxford and American CDC definitions, and 45 non-CFS subjects.

Participants completed questionnaires, were clinically examined, and had first morning urine specimens collected, which were screened by gas chromatography-mass spectrometry for changes in metabolite excretion.

Multivariate analysis of the urinary metabolite profiles differed significantly in the CFS patients compared to the non-CFS patients (P < 0.004). The CFS patients had increases in aminohydroxy-N-methylpyrrolidine (P < 0.00003, referred to as chronic fatigue symptom urinary marker 1, or CFSUM1), tyrosine (P < 0.02), beta-alanine (P < 0.02), aconitic acid (P < 0.05), and succinic acid (P < 0.05) and reductions in an unidentified urinary metabolite, CFSUM2 (P < 0.0007), alanine (P < 0.005), and glutamic acid (P < 0.02). CFSUM1, beta-alanine, and CFSUM2 were found by discriminant function analysis to be the first, second, and third most important metabolites, respectively for discriminating between CFS and non-CFS subjects.

The abundances of CFSUM1 and beta-alanine were positively correlated with symptom incidence (P < 0.01 and P < 0.001, respectively), symptom severity, core CFS symptoms, and SCL-90-R somatization (P < 0.00001), suggesting a molecular basis for CFS.

 

Source: McGregor NR, Dunstan RH, Zerbes M, Butt HL, Roberts TK, Klineberg IJ. Preliminary determination of a molecular basis of chronic fatigue syndrome. Biochem Mol Med. 1996 Apr;57(2):73-80. http://www.ncbi.nlm.nih.gov/pubmed/8733884