Liquid Chromatography-tandem mass spectrometry-based metabolite profiling in the hearts of germ-free and conventionally-raised mice

The microbiota is the community of microorganisms living on and in a biological system. It has shown to play a role in a broad range of medical conditions, including cardiovascular diseases. Germ-free (GF) mice grew under the condition lacking all microorganisms, in contrast to conventionally raised (CONV-R) mice colonized with a diverse microbiota. GF mice play a key role as tools to reveal the the causal relationship between microbiome and disease. In particular, GF mice present significant cardiac functional defects compared to CONV-R mice. The project's goal was to determine the spatial impact of GF vs. CONV-R status on cardiac metabolism across cardiac regions. 4 metabolite molecules showed significant differences by Random Forest analysis based on untargeted liquid chromatography-tandem mass spectrometry data. The four molecules are neighborhood of ADP-ribose (m/z = 588.11), ergothioneine (m/z = 230.1), neighborhood of dodecanoic acid (m/z = 177.13), and L-glutamine (m/z = 130.05). (Neighborhood results were generated from molecular networking.) Parallel reaction monitoring (PRM) was applied to provide more precise quantification results. In most locations, peak abundance significant difference was mapping in the locations: right ventricle free wall and left atrium part between germ-free and CONV-R conditions. Ergothioneine showed a difference in the left ventricle free wall bottom section. The metabolites may relate to the presence of microbiome and contribute to reducing the risk of cardiovascular disease

Impact of Visceral Leishmaniasis on Local Organ Metabolism in Hamsters.

Leishmania is an intracellular parasite with different species pathogenic to humans and causing the disease leishmaniasis. Leishmania donovani causes visceral leishmaniasis (VL) that manifests as hepatosplenomegaly, fever, pancytopenia and hypergammaglobulinemia. If left without treatment, VL can cause death, especially in immunocompromised people. Current treatments have often significant adverse effects, and resistance has been reported in some countries. Determining the metabolites perturbed during VL can lead us to find new treatments targeting disease pathogenesis. We therefore compared metabolic perturbation between L. donovani-infected and uninfected hamsters across organs (spleen, liver, and gut). Metabolites were extracted, analyzed by liquid chromatography-mass spectrometry, and processed with MZmine and molecular networking to annotate metabolites. We found few metabolites commonly impacted by infection across all three sites, including glycerophospholipids, ceramides, acylcarnitines, peptides, purines and amino acids. In accordance with VL symptoms and parasite tropism, we found a greater overlap of perturbed metabolites between spleen and liver compared to spleen and gut, or liver and gut. Targeting pathways related to these metabolite families would be the next focus that can lead us to find more effective treatments for VL

Building Natural Product Libraries Using Quantitative Clade-Based and Chemical Clustering Strategies

The success of natural product-based drug discovery is predicated on having chemical collections that offer broad coverage of metabolite diversity. We propose a simple set of tools combining genetic barcoding and metabolomics to help investigators build natural product libraries aimed at achieving predetermined levels of chemical coverage. It was found that such tools aided in identifying overlooked pockets of chemical diversity within taxa, which could be useful for refocusing collection strategies. We have used fungal isolates identified as Alternaria from a citizen-science-based soil collection to demonstrate the application of these tools for assessing and carrying out predictive measurements of chemical diversity in a natural product collection. Within Alternaria, different subclades were found to contain nonequivalent levels of chemical diversity. It was also determined that a surprisingly modest number of isolates (195 isolates) was sufficient to afford nearly 99% of Alternaria chemical features in the data set. However, this result must be considered in the context that 17.9% of chemical features appeared in single isolates, suggesting that fungi like Alternaria might be engaged in an ongoing process of actively exploring nature’s metabolic landscape. Our results demonstrate that combining modest investments in securing internal transcribed spacer (ITS)-based sequence information (i.e., establishing gene-based clades) with data from liquid chromatography-mass spectrometry (i.e., generating feature accumulation curves) offers a useful route to obtaining actionable insights into chemical diversity coverage trends in a natural product library. It is anticipated that these outcomes could be used to improve opportunities for accessing bioactive molecules that serve as the cornerstone of natural product-based drug discovery.Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye

Local Phenomena Shape Backyard Soil Metabolite Composition

Soil covers most of Earth’s continental surface and is fundamental to life-sustaining processes such as agriculture. Given its rich biodiversity, soil is also a major source for natural product drug discovery from soil microorganisms. However, the study of the soil small molecule profile has been challenging due to the complexity and heterogeneity of this matrix. In this study, we implemented high-resolution liquid chromatography–tandem mass spectrometry and large-scale data analysis tools such as molecular networking to characterize the relative contributions of city, state and regional processes on backyard soil metabolite composition, in 188 soil samples collected from 14 USA States, representing five USA climate regions. We observed that region, state and city of collection all influence the overall soil metabolite profile. However, many metabolites were only detected in unique sites, indicating that uniquely local phenomena also influence the backyard soil environment, with both human-derived and naturally-produced (plant-derived, microbially-derived) metabolites identified. Overall, these findings are helping to define the processes that shape the backyard soil metabolite composition, while also highlighting the need for expanded metabolomic studies of this complex environment.This research was supported by start-up funds from the University of Oklahoma (to L.-I.M.). Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye

Mapping of host-parasite-microbiome interactions reveals metabolic determinants of tropism and tolerance in Chagas disease

Chagas disease (CD) is a parasitic disease caused by Trypanosoma cruzi protozoa, presenting with cardiomyopathy, megaesophagus, and/or megacolon. To determine the mechanisms of gastrointestinal (GI) CD tissue tropism, we systematically characterized the spatial localization of infection-induced metabolic and microbiome alterations, in a mouse model of CD. Notably, the impact of the transition between acute and persistent infection differed between tissue sites, with sustained large-scale effects of infection in the esophagus and large intestine, providing a potential mechanism for the tropism of CD within the GI tract. Infection affected acylcarnitine metabolism; carnitine supplementation prevented acute-stage CD mortality without affecting parasite burden by mitigating infection-induced metabolic disturbances and reducing cardiac strain. Overall, results identified a previously-unknown mechanism of disease tolerance in CD, with potential for new therapeutic regimen development. More broadly, results highlight the potential of spatially resolved metabolomics to provide insight into disease pathogenesis and infectious disease drug development.Open Access fees paid for in whole or in part by the University of Oklahoma Libraries. This work was supported by start-up funds from the University of Oklahoma to L.-I.M. and the National Institute of Allergy and Infectious Diseases of the NIH under award number R21AI148886 to L.-I.M. Initial tissue collection was supported by a postdoctoral fellowship to L.-I.M. from the Canadian Institutes of Health Research (award number 338511; www.cihr-irsc.gc.ca/). Microbial community analysis was supported, in part, by an NIH grant (award number NIH 2R01-GM089886 to K.S). Immunological characterization was performed on instrumentation from the OU Protein Production and Characterization Core facility, supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the NIH under grant number P20GM103640. Histology samples were processed by the University of Oklahoma Health Sciences Center, Stephenson Cancer Center Tissue Pathology Shared Resource, supported by the National Cancer Institute Cancer Center Support Grant P30CA225520 and COBRE P20GM103639. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.Ye