We recently presented a three-pronged association study that integrated human intestinal microbiome data derived from shotgun-based sequencing with untargeted serum metabolome data and measures of host physiology. Metabolome and microbiome data are high dimensional, posing a major challenge for data integration. Here, we present a step-by-step computational protocol that details and discusses the dimensionality-reduction techniques used and methods for subsequent integration and interpretation of such heterogeneous types of data. Dimensionality reduction was achieved through a combination of data normalization approaches, binning of co-abundant genes and metabolites, and integration of prior biological knowledge. The use of prior knowledge to overcome functional redundancy across microbiome species is one central advance of our method over available alternative approaches. Applying this framework, other investigators can integrate various ‘-omics’ readouts with variables of host physiology or any other phenotype of interest (e.g., connecting host and microbiome readouts to disease severity or treatment outcome in a clinical cohort) in a three-pronged association analysis to identify potential mechanistic links to be tested in experimental settings. Although we originally developed the framework for a human metabolome–microbiome study, it is generalizable to other organisms and environmental metagenomes, as well as to studies including other -omics domains such as transcriptomics and proteomics. The provided R code runs in ~1 h on a standard PC.
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This research received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013): MetaHIT, grant agreement HEALTH-F4-2007-201052 and MetaCardis, grant agreement HEALTH-2012-305312. The Department of Bio and Health Informatics, Technical University of Denmark, and the Novo Nordisk Foundation Center for Basic Metabolic Research have in addition received support from the Innovative Medicines Initiative Joint Undertaking under grant agreement no. 115317 (DIRECT), the resources of which are composed of financial contributions from the European Union’s Seventh Framework Programme (FP7/2007–2013) and EFPIA companies’ in kind contribution. The Novo Nordisk Foundation Center for Protein Research received funding from the Novo Nordisk Foundation (grant agreement NNF14CC0001). The Novo Nordisk Foundation Center for Basic Metabolic Research is an independent research center at the University of Copenhagen partially funded by an unrestricted donation from the Novo Nordisk Foundation (http://www.metabol.ku.dk). A.Ø.P. received funding from the Lundbeck Foundation (grant R218-2016-1367) and S.D.E. received funding from Agence Nationale de la Recherche MetaGenoPolis grant ‘Investissements d’avenir’ ANR-11-DPBS-0001.
The authors declare no competing interests.
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Key references using this protocol
Pedersen, H. K. et al. Nature 535, 376–381 (2016): https://doi.org/10.1038/nature18646
Integrated supplementary information
Supplementary Figure 1 Composition and concentration range of lipids and polar metabolites detected in the human serum samples in the MetaHIT cohort.
The polar metabolites include both fully identified metabolites as well as metabolites identified only at the compound class level (n=778) while the lipids include only fully identified such (n=287).
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Pedersen, H.K., Forslund, S.K., Gudmundsdottir, V. et al. A computational framework to integrate high-throughput ‘-omics’ datasets for the identification of potential mechanistic links. Nat Protoc 13, 2781–2800 (2018). https://doi.org/10.1038/s41596-018-0064-z
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