Quantitative Metabolomics by 1H-NMR and LC-MS/MS Confirms Altered Metabolic Pathways in Diabetes

Abstract

Insulin is as a major postprandial hormone with profound effects on carbohydrate, fat, and protein metabolism. In the absence of exogenous insulin, patients with type 1 diabetes exhibit a variety of metabolic abnormalities including hyperglycemia, glycosurea, accelerated ketogenesis, and muscle wasting due to increased proteolysis. We analyzed plasma from type 1 diabetic (T1D) humans during insulin treatment (I+) and acute insulin deprivation (I-) and non-diabetic participants (ND) by 1H nuclear magnetic resonance spectroscopy and liquid chromatography-tandem mass spectrometry. The aim was to determine if this combination of analytical methods could provide information on metabolic pathways known to be altered by insulin deficiency. Multivariate statistics differentiated proton spectra from I- and I+ based on several derived plasma metabolites that were elevated during insulin deprivation (lactate, acetate, allantoin, ketones). Mass spectrometry revealed significant perturbations in levels of plasma amino acids and amino acid metabolites during insulin deprivation. Further analysis of metabolite levels measured by the two analytical techniques indicates several known metabolic pathways that are perturbed in T1D (I-) (protein synthesis and breakdown, gluconeogenesis, ketogenesis, amino acid oxidation, mitochondrial bioenergetics, and oxidative stress). This work demonstrates the promise of combining multiple analytical methods with advanced statistical methods in quantitative metabolomics research, which we have applied to the clinical situation of acute insulin deprivation in T1D to reflect the numerous metabolic pathways known to be affected by insulin deficiency.

Cordyceps sinensis protects against liver and heart injuries in a rat model of chronic kidney disease: a metabolomic analysis

“…The significant depletion of hepatic glutathione in the OP rats was a marker of the disruption of cellular redox status related to CKD-induced liver injury. However, increased glutathione turnover was observed in CS rats, which implied that C sinensis mitigated CKD-related liver injury via its antioxidative activity [48] . Taurine, a free amino acid, is known to counteract oxidative stress in tissues (liver, kidney and retina) [49,50] .…”

Metabolomics in diabetes research

“…These findings from human patients can be summarised as follows: i) As expected, diabetic patients exhibited differences in glucose metabolism. Patients with T1DM under insulin deprivation (Lanza et al 2010) or in T2DM (Li et al 2009, Suhre et al 2010) demonstrated elevated glucose or mannose levels compared with healthy controls. Furthermore, in both T1DM and T2DM patients (Messana et al 1998, Zuppi et al 2002 increased lactate levels were observed, at which these levels increased with the grade of glucosuria in T2DM patients (Messana et al 1998).…”

“…iii) The above-mentioned results were further confirmed in regards to the levels of ketone bodies during diabetes. Higher levels of acetone, acetoacetate and b-hydroxybutyrate were observed in insulin-deprived T1DM (Lanza et al 2010) and T2DM (Nicholson et al 1984, Messana et al 1998, Suhre et al 2010) subjects, indicating ketoacidotic metabolic decompensation. iv) Additionally, alterations in intestinal microflora-associated metabolites have been detected.…”

“…A broad range of amino acids, including leucine, isoleucine, valine, phenylalanine, tyrosine, alanine, tryptophan and homocitrulline, has been shown to be substantially increased in T1DM (Lanza et al 2010) or T2DM patients (Messana et al 1998, Suhre et al 2010 as well as among subjects with obesity or impaired glucose tolerance (Zhao et al 2010b). In addition, these findings have been confirmed by studies that revealed positive associations between amino acid levels and the homoeostasis model assessment index ) and insulin resistance of obese subjects, according to Bergman's minimal model (Huffman et al 2009).…”

UPLC-based metabonomic applications for discovering biomarkers of diseases in clinical chemistry

“…Another UPLC-based metabonomic study has revealed significant perturbations in plasma amino acids and amino acid metabolites during insulin deprivation in T1D. Several known metabolic pathways are perturbed in acute insulin deprivation T1D [81]. Plasma branched chain amino acids are increased in untreated T1D [82] and have been attributed to the breakdown of muscle protein and release of amino acids in the circulation [83] and liver [84].…”