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Untargeted metabolomics molecular features data for plasma of 20 Peromyscus leucopus and 20 Mus musculus treated with LPS or controls

Citation

Barbour, Alan; Islam, Nurul; Milovic, Ana; Belisle, John (2021), Untargeted metabolomics molecular features data for plasma of 20 Peromyscus leucopus and 20 Mus musculus treated with LPS or controls, Dryad, Dataset, https://doi.org/10.7280/D12M4N

Abstract

Animals that are competent natural reservoirs of zoonotic diseases commonly suffer little morbidity from the pathogens they persistently harbor. The mechanisms of this infection tolerance and the trade-off costs are poorly understood. We used exposure to a single dose of lipopolysaccharide (LPS) endotoxin as an experimental model of inflammation to compare the responses of the cricentine rodent Peromyscus leucopus, the white-footed deermouse, to that of Mus musculus, the standard laboratory model for pathogenesis studies. Four hours after injection with either LPS or saline, blood and spleen and liver tissues were collected postmortem and subjected to RNA-seq, untargeted metabolomics, and specific RT-qPCR. This was followed by analysis of differential expression at the gene, pathway, and empirical network levels. The deermice showed the same signs of sickness as the mice with LPS exposure, and in addition demonstrated comparable increases in levels of corticosterone and expression of interleukin (IL)-6, tumor necrosis factor, IL-1b, and acute phase reactants, including C-reactive protein. But whereas the M. musculus response to LPS was best-characterized by network analysis as cytokine-associated, the P. leucopus response was dominated by pathway terms associated with neutrophil activity. Dichotomies between the species in expression profiles of arginase 1 and nitric oxide synthase 2, as well as the ratios of IL-10 to IL-12, were consistent with a type M1 polarized macrophage response in the mice and a type M2 or alternatively-activated response in the deermice. Analysis of metabolites in the plasma and RNA in the tissues revealed differences between the two species in tryptophan metabolism during response to LPS. Two up-regulated genes in particular signified the difference between the species: Slpi (secretory leukocyte proteinase inhibitor) and Ibsp (integrin-binding protein sialoprotein). The latter was previously unrecognized in the context of inflammation or infection. Key RNA-seq findings in P. leucopus were replicated in a second LPS experiment with older animals, in a systemic bacterial infection model, and with cultivated fibroblasts. Taken together, the results indicate that the deermouse possesses several adaptive traits to moderate effects of inflammation and oxidative stress ensuing from infection. This seems to be at the cost of infection persistence and that is to the benefit of the pathogen.  

Methods

Plasma samples were collected from 20 Peromyscus leucopus and 20 Mus musculus (BALB/c strain) 4 hours after intraperitoneal injection with E. coli lipopolysaccharide at 10 micrograms/gm body weight (12 of each species) or with normal saline alone (8 of each species). The animals of each species were equally divided by sex.  Forty microliter volumes of plasma were extracted with 120 microliters methanol containing as internal standards phenylalanine d5 (175 ng/mL), 1-methyl tryptophan (37.5 ng/mL), and arachnidonoyl amide (30 ng/mL). After precipitated proteins were removed by centrifugation, the supernatant was dried under vacuum and then suspended in 50% methanol. Aliquots of 10 microliter were subjected to high pressure liquid chromatography (HPLC) and quadrupole (Q) time-of-flight (TOF) mass spectrometry (MS) with periodic inclusion of pooled samples for quality control. Metabolites were separated on an Agilent Technologies Poroshell C8 column (100 x 2.1 mm, 2.7 micron) with a gradient of acetonitrile and water both containing 0.1% formic acid with an Agilent 1260 HPLC pump. The eluent was introduced into an Agilent Technologies 6520 Q-TOF-MS instrument equipped with an electrospray ionization source. The parameters for the analysis were a capillary voltage of 4000 V, fragmenter voltage of 120 V, gas at 310° C, gas flow of 10 L/min, and nebulizer pressure of 45 psig. Data were acquired in the positive ion mode at a scan range of 75-1700 for the mass-to-charge ratio (m/z) and at a rate of 1.67 spectra per second. The raw data files were converted to the XML-based mzML format with Proteowizard. The files were then processed for peak picking, grouping, and retention time correction with the XCMS suite of software. The centWave algorithm was applied to detect chromatographic peaks with these parameter settings: ≤ 30 ppm for m/z deviation in consecutive peaks, signal to noise ratio of 10, a prefilter of 3 scans with peak intensity of ≥ 750, and 10 to 45 s for peak width. Molecular features (MF), defined by m/z and retention time, were grouped across samples using a bandwidth of 15 and overlapping m/z slice of 0.02. Retention time correction was performed with the retcor algorithm of XCMS. 

Usage Notes

The dataset consists of an Excel workbook with two sheets. The first sheet contains the data for P. leucopus and the second sheet contains the data for M. musculus. The fold change values are for the LPS-treated to the control values.  Included on each are the quality control (QC) values for each run. 

Funding

National Institutes of Health, Award: AI136523