Spraggins, J. M. | bioRxiv Science

bioRxiv2020

Spatially-targeted proteomics of the host-pathogen interface during staphylococcal abscess formation

Staphylococcus aureus is a common cause of invasive and life-threatening infections that are often multi-drug resistant. To develop novel treatment approaches, a detailed understanding of the complex host-pathogen interactions during infection is essential. This is particularly true for the molecular processes that govern the formation of tissue abscesses, as these heterogeneous structures are important contributors to staphylococcal pathogenicity. To fully characterize the developmental process leading to mature abscesses, temporal and spatial analytical approaches are required. Spatially targeted proteomic technologies, such as micro liquid extraction surface analysis, offer insight into complex biological systems including detection of bacterial proteins, and their abundance in the host environment. By analyzing the proteomic constituents of different abscess regions across the course of infection, we defined the immune response and bacterial contribution to abscess development through spatial and temporal proteomic assessment. The information gathered was mapped to biochemical pathways to characterize the metabolic processes and immune strategies employed by the host. These data provide insights into the physiological state of bacteria within abscesses and elucidate pathogenic processes at the host-pathogen interface.

microbiology↗

bioRxiv2020

Lipid Landscape of the Human Retina and Supporting Tissues Revealed by High Resolution Imaging Mass Spectrometry

The human retina evolved to facilitate complex visual tasks. It supports vision at light levels ranging from starlight to sunlight, and its supporting tissues and vasculature regulate plasma-delivered lipophilic essentials for vision, including retinoids (vitamin A derivatives). The human retina is of particular interest because of its unique anatomic specializations for high-acuity and color vision that are also vulnerable to prevalent blinding diseases. The retinas exquisite cellular architecture is composed of numerous cell types that are aligned horizontally, giving rise to structurally distinct cell, synaptic, and vascular layers that are visible in histology and in diagnostic clinical imaging. Suitable for retinal investigations, MALDI imaging mass spectrometry (IMS) technologies are now capable of providing images at low micrometer spatial resolution with high levels of chemical specificity. In this study, a multimodal imaging approach combined with a recently developed method of high accuracy multi-image registration was used to define the localization of lipids in human retina tissue at laminar, cellular, and sub-cellular levels. Data acquired by IMS combined with autofluorescence and bright-field microscopy of human retina sections in macular and peripheral regions indicate differences in distributions and abundances of lipid species across and within single cell types. Of note is localization of signals within specific layers of macula, localization within different compartments of photoreceptors and RPE, complementarity of signals between macular retina and non-macular RPE, and evidence that lipids differing by a single double bond can have markedly different distributions.

biochemistry↗