Spatially Targeted Proteomics of the Host–Pathogen Interface during Staphylococcal Abscess Formation

Abstract

Staphylococcus aureus is a common cause of invasive and life-threatening infections that are often multidrug 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 microliquid 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.

Uncovering Molecular Heterogeneity in the Kidney With Spatially Targeted Mass Spectrometry

“…One study identified 67 proteins only detected in glomeruli and 25 unique to proximal tubules, with many additional proteins shared by both regions being conserved housekeeping and cytoskeletal proteins (Sigdel et al, 2020). Notably, this study found that proximal tubule proteins comprised a greater fraction of the homogenate proteome than glomerular proteins, and known glomerular markers such as podocin, eva-1 homolog B, and claudin-5 could be identified in dissected glomeruli but not in kidney homogenate (Guiberson et al, 2021). This underscores the value of a spatially targeted approach to study glomeruli (Sigdel et al, 2020).…”

“…Spatially targeted MS technologies are characterized as either profiling experiments, where a single spectral signature is collected from a discrete cell type or FTU, or as imaging experiments where MS data are collected from an array of measurement locations (i.e., pixels) to visualize molecular distributions in situ (Figure 1). Micro-liquid extraction surface analysis (microLESA) is a profiling approach using a robotic fluidic printer to deposit trypsin droplets to specific tissue regions for surface protein digestion (Ryan et al, 2019;Guiberson et al, 2021). Peptides are then recovered using a larger droplet and subjected to liquid chromatography-tandem MS (LC-MS/MS) for protein identification.…”

Spatial relationships of intra-lesion heterogeneity in Mycobacterium tuberculosis microenvironment, replication status, and drug efficacy

“…Finally, the approaches and concepts established here are likely to also have broad applicability to other bacterial species, with the burgeoning appreciation of the importance of spatial heterogeneity in varied aspects of bacterial-host interactions for infection outcome of many pathogens. This spans spatial differences in Staphylococcus aureus biology in abscesses and Yersinia pseudotuberculosis physiology and host response within microcolonies [ 59 – 62 ], to microniches in the gastrointestinal tract and its implications for bacterial survival and growth [ 63 , 64 ]. Spatial differences within biofilms of bacteria such as Pseudomonas aeruginosa and Vibrio cholerae have also recently been elegantly demonstrated [ 65 , 66 ].…”

Clostridioides difficile infection induces a rapid influx of bile acids into the gut during colonization of the host

“…Our findings stem from the use of cutting-edge IMS technology that allows for untargeted discovery-based visualization of molecular species, revealing spatial localization and intensity patterns that would be impossible to detect with traditional LC-MS/MS alone ( Figure S1 ). This approach has been useful in a variety of host-pathogen interaction studies, such as in Staphylococcus aureus infections ( Guiberson et al, 2021 ). The incorporation of MALDI IMS to study S. aureus soft tissue abscesses allows for molecular profiling of the bacterial nidus and surrounding tissue, revealing molecular changes that occur in this region during infection ( Cassat et al, 2018 ).…”