NMR and metabolism

NMR spectroscopy

NMR spectroscopy is a powerful tool for detecting, identifying and quantifying a wide range of high and low molecular weight compounds without any prior selection and with little sample preparation. Furthermore, it provides invaluable information about the detailed molecular and chemical structure of the measured compounds.
NMR spectroscopy takes advantage of the fact that certain nuclei possess a spin, besides their mass and charge. When placed in a magnetic field, the magnetic moment experiences a torque which results in the axis of the spin precessing about the axis of the magnetic field in one of the allowed orientations, for 1H, 13C, 19F and 31P nuclei, parallel to the external magnetic field (lower energy state) and anti-parallel (higher energy state) to it. The difference in energy between these two states is related to the strength of the external magnetic field. Therefore, NMR spectroscopy typically profits from strong magnetic fields. Different resonances in the spectrum can be seen with a) different chemical shifts depending on the chemical environment of each nuclei and b) different intensities which are related to the concentration of the compound and the number of protons that give rise to that signal. Therefore, NMR can be quantitative, if the experiment is carried out appropriately.

Chances and challenges of NMR spectroscopy
1H NMR-based metabolomics has shown its usefulness in analysing a variety of biofluids and tissue extracts. We have applied the technique to urine, plasma, different tissue extracts (e.g. liver, kidney, and heart) and aqueous extracts of feces and gut luminal content and different foods (e.g. fruit juices, coffee and wine). The technique delivers a quantitative overview of the abundant metabolites in a given biological sample without the necessity of exhaustive sample preparation. The absence of analytical suppression effects allows a quantitative and therefore inter-sample comparison of main metabolite quantities. Through the availability of high-field instruments and the use of cryogenic probes sensitivity increases and 2-dimensional experiments are possible in a feasible time. Especially 2D experiments (e.g. 1H-13C-HSQC, 1H-1H-TOCSY, J-resolved) are necessary to overcome the problems of signal overlap and annotation of the signals to chemical structures. It is particularly the identification of detected features that poses a bottleneck in both NMR and MS metabolomics research. Therefore, through identification investigations are needed in order to assign metabolites or chemical structures to signals. This can be achieved by comparison of chemical shifts to information available in publicly available databases such as HMDB, BMRB and BML-NMR and literature. In addition, a series of 2D NMR spectra are needed for metabolite assignment to enable a comprehensive description of metabolites present in biological matrices.
Furthermore, 2D experiments offer a much reduced signal overlap and therefore increase the number of elucidated metabolites in a sample.

Our research interests

Spatial resolution of the gut for microbiome-metabolome research. The microbiota of the gastrointestinal tract displays compositional differences between mucus and lumen, and longitudinally from cecum to colon and feces. We have reported spatial variation of gut luminal metabolites in mice that directly link to microbial breakdown of carbohydrates and proteins in the cecum and re-absorption processes in the colon. Such metabolic variation is affected by the microbiota but might also directly promote the feedback for growth of selected bacteria along the gut and trigger signaling pathways for the microbiome and the host with effects in health and disease.

Urine metabolomics research in health and disease. Our interest is to identify the contribution of environmental factors such as diet, drugs and the gut microbiome on the metabolic phenotype. We furthermore metabolically characterize samples from different intervention trials and cohorts in order to elucidate potential biomarkers in cardiovascular disease and chronic kidney disease. We continuously work on the comprehensive chemical characterization of foods and beverages and the elucidation of associated food biomarkers. Further interests include the metabolic phenotyping of human individuals for population stratification using cohort studies and for personalizing human lifestyle interventions.

Application of NMR metabolomics to a variety of biological matrices across different species. NMR metabolomics can be applied to different biological samples, while sample preparation remains similar. Therefore, we are interested in characterizing the metabolome of many biological matrixes e.g. different biofluids and extracts from any bodily tissue.
The translatability of e.g. rodent models to humans is limited. Even though animal models offer powerful tools to investigate principles of metabolic pathways and interplay between host and microbiota, it is of utmost importance to turn to animal models having closer proximity to humans in terms of gut physiology, immunology, and nutrition. We are interested in investigating the metabolome of different animal models in order to trace complex interactions between host and microbiota regarding nutritional interventions and disease etiology, while limiting the large variation and exogenous influences generally observed in humans.

Selected publications

1H NMR-based metabolite profiling workflow to reduce inter-sample chemical shift variations in urine samples for improved biomarker discovery. Gil RB, Lehmann R, Schmitt-Kopplin P, Heinzmann SS. Anal Bioanal Chem. 2016.

Challenges of metabolomics in human gut microbiota research. Smirnov KS, Maier TV, Walker A, Heinzmann SS, Forcisi S, Martinez I, Walter J, Schmitt-Kopplin P. Int J Med Micro 2016.

2-Furoylglycine as a candidate biomarker of coffee consumption. Heinzmann SS, Holmes E, Kochhar S, Nicholson JK, Schmitt-Kopplin P. J Agric Food Chem. 2015 Sep 30;63(38):8615-21.

Gut metabolites and bacterial community networks during a pilot intervention study with flaxseeds in healthy adult men. Lagkouvardos I, Kläring K, Heinzmann SS, Platz S, Scholz B, Engel KH, Schmitt-Kopplin P, Haller D, Rohn S, Skurk T, Clavel T. Mol Nutr Food Res. 2015 May 18.

Chemical messages in 170-year-old champagne bottles from the Baltic Sea: Revealing tastes from the past. Jeandet P, Heinzmann SS, Roullier-Gall C, Cilindre C, Aron A, Deville MA, Moritz F, Karbowiak T, Demarville D, Brun C, Moreau F, Michalke B, Liger-Belair G, Witting M, Lucio M, Steyer D, Gougeon RD, Schmitt-Kopplin P. Proc Natl Acad Sci U S A. 2015 May 12;112(19):5893-8.

Deep metabotyping of the murine gastrointestinal tract for the visualization of digestion and microbial metabolism. Heinzmann SS, Schmitt-Kopplin P. J Proteome Res. 2015 May 1;14(5):2267-77.

Metabolomics in GI disease and the influence of the gut microbiome on host metabolism. In: Gobal Metabolic Profiling: Clinical Applications.
Walker A, Heinzmann SS, P. Schmitt-Kopplin. Future Medicine. January 2014, Pages 84-95. doi: 10.4155/ebo.13.566

Stability and robustness of human metabolic phenotypes in response to sequential food challenges.
Heinzmann SS, Merrifield CA, Rezzi S, Kochhar S, Lindon JC, Holmes E, Nicholson JK. J Proteome Res. 2012 Feb 3;11(2):643-55.

Metabolic profiling strategy for discovery of nutritional biomarkers: proline betaine as a marker of citrus consumption.
Heinzmann SS, Brown IJ, Chan Q, Bictash M, Dumas ME, Kochhar S, Stamler J, Holmes E, Elliott P, Nicholson JK. Am J Clin Nutr. 2010 Aug;92(2):436-43.