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The effect of monoclonal antibodies against HSP60 on Histoplasma capsulatum extracellular vesicles


EMSL Project ID
50042

Abstract

The capacity of the human fungal pathogen Histoplasma capsulatum (Hc) to cause severe invasive disease is attributed to the fungus’ ability to subvert host responses, especially in the setting of immune compromise due to advanced HIV infection. For example, the capacity of the fungus to impair phagosome maturation and the presence of melanin in the fungal cell wall contribute to the capacity of the fungus to survive intracellularly and avoid host surveillance as well as block the effects of host effector responses. We have shown that Hc produces extracellular vesicles containing biologically active molecules. However, many questions on disease pathogenesis arise from this process of vesiculogenesis. We will explore how protective and non-protective antibodies regulate the production and release of extracellular vesicles from Hc. We are pursuing this work based on our findings that protective antibodies to Hc alter gene expression and that cross-linking by antibodies changes the outcome of interactions with host effector cells. Using a pair of protective and non-protective monoclonal antibodies (mAb) that bind to the same region on heat shock protein 60 expressed on the Hc cell surface, we will determine the mAbs’ capacity to alter the formation and secretion of these bilayered vesicles as well as their impact on the cargo within the vesicles. The resources located at EMSL will be essential for the detailed characterization of the vesicular composition and the impact of antibody treatment on it. We are pursuing this work based on our observations that the vesicles can alter the behavior of host cells and that the cargo within the vesicles includes compounds that are toxic to host cells. The results of the studies in this project will provide new insights into the basic biology of Hc, elucidate new activities of antibody, and serve as a potential foundation for new therapeutic approaches to combat this important fungus as well as other eukaryotic pathogens.

Project Details

Start Date
2017-10-04
End Date
2018-09-30
Status
Closed

Team

Principal Investigator

Ernesto Nakayasu
Institution
Pacific Northwest National Laboratory

Team Members

Christina Stevenson
Institution
Pacific Northwest National Laboratory

Samuel Payne
Institution
Pacific Northwest National Laboratory

Charles Ansong
Institution
National Institutes of Health

Thomas Metz
Institution
Pacific Northwest National Laboratory

Related Publications

Baltazar L.M., D. Zamith-Miranda, M.C. Burnet, H. Choi, L. Nimrichter, E.S. Nakayasu, and J.D. Nosanchuk. 2018. "Concentration-dependent protein loading of extracellular vesicles released by Histoplasma capsulatum after antibody treatment and its modulatory action upon macrophages." mSphere 8. PNNL-SA-124828. doi:10.1038/s41598-018-25665-5
Matos Baltazar L, Nakayasu ES, Sobreira TJ, Choi H, Casadevall A, Nimrichter L, Nosanchuk JD. "Antibody Binding Alters the Characteristics and Contents of Extracellular Vesicles Released by Histoplasma capsulatum". mSphere. 2016 Mar 30;1(2). pii: e00085-15. doi: 10.1128/mSphere.00085-15. eCollection 2016 Mar-Apr.