January 2020 Meeting

Speaker: Alison Scott, University of Maryland

Topic: Exploring the spatially-resolved lipidome during lung infection by Gram-negative pathogens using mass spectrometry imaging

Date: Monday, January 13th, 2020

Time: 6:15 pm Dinner, 7:15 pm Presentation

Location: Shimadzu Scientific Instruments, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Meghan Burke (meghan.burke@nist.gov) by Friday, January 10th if you will be attending the dinner.

Abstract: Mass spectrometry imaging (MSI) is a technique for mapping the spatial distributions of molecules in sectioned tissue. Histology-preserving tissue preparation methods are central to successful MSI studies. Common fixation methods, used to preserve tissue morphology, can result in artifacts in the resulting MSI experiment including delocalization of analytes, altered adduct profiles, and loss of key analytes due to irreversible cross-linking and diffusion. This is especially troublesome in lung and airway samples, in which histology and morphology is best interpreted from 3D reconstruction, requiring the large and small airways to remain inflated during analysis. We developed an MSI-compatible inflation containing as few exogenous components as possible, forgoing perfusion, fixation, and addition of salt solutions upon inflation that resulted in an ungapped 3D molecular reconstruction through more than 300 microns. We characterized a series of polyunsaturated phospholipids (PUFA-PLs), specifically phosphatidylinositol (-PI) lipids linked to lethal inflammation in bacterial infection and mapped them in serial sections of inflated mouse lung. PUFA-PIs were identified using spatial lipidomics and determined to be spatially determinant markers of major airway features using unsupervised hierarchical clustering. Using this preparation in combination with high-content lipidome imaging, we characterized the dynamic response of the same host lipids in the context of infection by Gram-negative pathogens in mouse lungs. Two infection models were used (Francisella novicida and Pseudomonas aeruginosa) to illustrate the divergent innate immune lipid response from Toll-like receptor 4 (TLR4)-silent and TLR4-stimulating pathogens, respectively. Network analysis of the lipid response was indicative of a neutrophil-driven response to TLR4-stimulating infection. In combination, the lung inflation method and infection modeling facilitate a new portal to understand the complex role of host lipid remodeling in the innate immune response.

December 2019 Meeting

Speaker: Asher Newsome, Smithsonian Institution

Topic: Ambient Sampling and Ionization for Mass Spectrometry of Museum Objects
and Materials

Date: Monday, December 16th, 2019

Time: 6:15 pm Dinner, 7:15 pm Presentation

Location: Shimadzu Scientific Instruments, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Meghan Burke (meghan.burke@nist.gov) by Friday, December 13th if you will be attending the dinner.

Abstract: The pace of development of ambient mass spectrometry has hardly slowed since kicking off fifteen years ago. Whether a given technique moves from academia to industry or follows some other path, often a design originally intended to be a general-purpose analytical MS tool – versatile, based on fundamental principles, relatively open-source – becomes increasingly engineered toward niche applications, particularly the biomedical and defense markets. With some 150 million objects (including living specimens) in its collection that have been selected for conservation and are available for study, the interests of the Smithsonian Institution fill every niche. The versatility, modularity, and throughput of our mass spectrometry systems are therefore a top priority. A varied selection of our recent projects using ambient ionization, direct analysis in real time (DART), and solid phase microextraction (SPME) to analyze ancient, historic, and modern objects is presented, as well as some of our instrumental modifications to accommodate the unique needs of a museum.

November 2019 Meeting

Speaker: Xiaoyu Yang, National Institute of Standards and Technology

Topic: Searching a Comprehensive High Resolution Tandem Mass Spectral Library for Accurate Metabolite Identification

Date: Monday, November 18th, 2019

Time: 6:15 pm Dinner, 7:15 pm Presentation

Location: Shimadzu Scientific Instruments, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Meghan Burke (meghan.burke@nist.gov) by Friday, November 15th if you will be attending the dinner.

Abstract: Identifying metabolites from millions of electrospray-generated tandem mass spectra is highly challenging, especially in view of the complex chemistry occurring in the electrospray process. We are working to assist in the identification process through the development of a comprehensive reference tandem mass spectral library. We will describe our two part approach. First, we are rapidly building a fully annotated library of all major ions generated in the electrospray process for compounds of analytical interest. Second, we are extending search algorithms to identify compounds not present in the library, but which have similar fragmentation mechanisms. We will describe our latest developments in these areas, with a focus on human metabolite identification.

October 2019 Meeting

Speaker: Leslie Hicks, University of North Carolina at Chapel Hill

Topic: Investigating plant-derived antimicrobial peptides using PepSAVI-MS

Date: Monday, October 21st, 2019

Time: 6:15 pm Dinner, 7:15 pm Presentation

Location: Shimadzu Scientific Instruments, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Meghan Burke (meghan.burke@nist.gov) by Friday, October 18th if you will be attending the dinner.

Abstract: As current methods for antibiotic drug discovery are being outpaced by the rise of antimicrobial resistance, new methods and innovative technologies are crucial to replenish our dwindling arsenal of antimicrobial therapeutics. While natural products are a well-studied source of biologically active small molecules, peptidyl factors contributing to their medicinal properties remain largely unexplored. To this end, we have developed the PepSAVI-MS to identify bioactive peptide targets from complex biological samples. The developed platform is highly versatile as it is adaptable to any natural product source of peptides and can test against diverse physiological targets, including bacteria, fungi, and cancer cells for which there is a developed bioassay. As such, we demonstrated extension of this pipeline to fungal and bacterially-sourced AMPs and are beginning to probe the vast array of botanical natural product sources to prioritize highly active species for downstream analysis.

September 2019 Meeting

Speaker: Joseph Zaia, Boston University School of Medicine

Topic: Proteomics, glycomics, and glycoproteomics of matrisome molecules

Date: Monday, September 16th, 2019

Time: 6:15 pm Dinner, 7:15 pm Presentation

Location: Shimadzu Scientific Instruments, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Meghan Burke (meghan.burke@nist.gov) by Friday, September 16th if you will be attending the dinner.

Abstract: The most straightforward applications of proteomics database searching involve intracellular proteins. While intracellular gene products number in the thousands, their well-defined post-translational modifications (PTMs) makes database searching practical. By contrast, cell surface and extracellular matrisome proteins pass through the secretory pathway where many become glycosylated, modulating their physicochemical properties, adhesive interactions, and diversifying their functions. While matrisome proteins number only a few hundred, their high degree of complex glycosylation multiplies the number of theoretical proteoforms by orders of magnitude. Given that extracellular networks that mediate cell-cell and cell-pathogen interactions in physiology depend on glycosylation, it is important to characterize the proteomes, glycomes and glycoproteomes of matrisome molecules that exist in a given biological context. In this presentation, I will summarize proteomics approaches for characterizing matrisome molecules, with an emphasis on applications to brain diseases.