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Biomolecular Ultrasound Imaging of Phagolysosomal Function

Ling, Bill and Lee, Justin and Maresca, David and Lee-Gosselin, Audrey and Malounda, Dina and Swift, Margaret B. and Shapiro, Mikhail G. (2020) Biomolecular Ultrasound Imaging of Phagolysosomal Function. ACS Nano, 14 (9). pp. 12210-12221. ISSN 1936-0851. https://resolver.caltech.edu/CaltechAUTHORS:20200911-133137357

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Abstract

Phagocytic clearance and lysosomal processing of pathogens and debris are essential functions of the innate immune system. However, the assessment of these functions in vivo is challenging because most nanoscale contrast agents compatible with noninvasive imaging techniques are made from nonbiodegradable synthetic materials that do not undergo regular lysosomal degradation. To overcome this challenge, we describe the use of an all-protein contrast agent to directly visualize and quantify phagocytic and lysosomal activities in vivo by ultrasound imaging. This contrast agent is based on gas vesicles (GVs), a class of air-filled protein nanostructures naturally expressed by buoyant microbes. Using a combination of ultrasound imaging, pharmacology, immunohistology, and live-cell optical microscopy, we show that after intravenous injection, GVs are cleared from circulation by liver-resident macrophages. Once internalized, the GVs undergo lysosomal degradation, resulting in the elimination of their ultrasound contrast. By noninvasively monitoring the temporal dynamics of GV-generated ultrasound signal in circulation and in the liver and fitting them with a pharmacokinetic model, we can quantify the rates of phagocytosis and lysosomal degradation in living animals. We demonstrate the utility of this method by showing how these rates are perturbed in two models of liver dysfunction: phagocyte deficiency and nonalcoholic fatty liver disease. The combination of proteolytically degradable nanoscale contrast agents and quantitative ultrasound imaging thus enables noninvasive functional imaging of cellular degradative processes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acsnano.0c05912DOIArticle
ORCID:
AuthorORCID
Ling, Bill0000-0002-1276-7204
Lee, Justin0000-0002-3657-4386
Maresca, David0000-0002-4921-6406
Lee-Gosselin, Audrey0000-0002-2431-2741
Malounda, Dina0000-0001-7086-9877
Shapiro, Mikhail G.0000-0002-0291-4215
Additional Information:© 2020 American Chemical Society. Received: July 16, 2020; Accepted: September 9, 2020; Published: September 9, 2020. The authors thank A. Collazo and the Caltech Biological Imaging Facility of the Beckman Institute for assistance with optical microscopy; the City of Hope Analytical Cytometry Core Facility for assistance with cell sorting; the UCLA Translational Pathology Core Laboratory for assistance with tissue histology; J. Szablowski for helpful advice on tissue immunofluorescence; L. Frankiw and D. Baltimore for lentiviral plasmids and assistance with macrophage cell lines; and D. Piraner, A. Lakshmanan and D. Wu for fruitful discussions. This research was supported by the National Institutes of Health (Grant R01-EB018975 to M.G.S.) and the Human Frontier Science Program (grant RGP0050/2016 to M.G.S.). B.L was supported by the NIH/NRSA Pre-Doctoral Training Grant (T32GM07616) and the Caltech Center for Environmental and Microbial Interactions. J.L. was supported by the Paul and Daisy Soros Fellowship. D. Maresca was supported by the Human Frontier Science Program Cross-Disciplinary Fellowship (LT000637/2016). Related research in the Shapiro laboratory is supported by the Pew Charitable Trust, the David and Lucile Packard Foundation, and the Heritage Medical Research Institute. Data and Code Availability: All gas vesicles, plasmids, data, and code are available from the authors upon reasonable request. Author Contributions: B.L. and M.G.S. conceived the research. B.L. conducted the in vivo imaging experiments with assistance from D. Maresca and A.L.-G. B.L. and J.L. conducted in vitro macrophage experiments. B.L. established and validated the pharmacology and disease models with assistance from M.B.S. D. Malounda prepared gas vesicles for experiments. B.L. and M.G.S. wrote the paper with input from all other authors. M.G.S. supervised the research. The authors declare no competing financial interest.
Group:Caltech Center for Environmental Microbial Interactions (CEMI), Heritage Medical Research Institute
Funders:
Funding AgencyGrant Number
NIHR01-EB018975
Human Frontier Science ProgramRGP0050/2016
NIH Predoctoral FellowshipT32GM07616
Caltech Center for Environmental Microbial Interactions (CEMI)UNSPECIFIED
Paul and Daisy Soros FellowshipUNSPECIFIED
Human Frontier Science ProgramLT000637/2016
Pew Charitable TrustUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Heritage Medical Research InstituteUNSPECIFIED
Subject Keywords:ultrasound, contrast agents, phagocytosis, lysosomes, liver disease, reticuloendothelial system
Issue or Number:9
Record Number:CaltechAUTHORS:20200911-133137357
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200911-133137357
Official Citation:Biomolecular Ultrasound Imaging of Phagolysosomal Function. Bill Ling, Justin Lee, David Maresca, Audrey Lee-Gosselin, Dina Malounda, Margaret B. Swift, and Mikhail G. Shapiro. ACS Nano 2020 14 (9), 12210-12221; DOI: 10.1021/acsnano.0c05912
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105348
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:14 Sep 2020 14:10
Last Modified:20 Oct 2020 21:04

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