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A Soluble PrP^C Derivative and Membrane-Anchored PrP^C in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

ABSTRACT: Nonpathogenic cellular prion protein (PrP^C) demonstrates anti-inflammatory activity; however, the responsible mechanisms are incompletely defined. PrP^C exists as a GPI-anchored membrane protein in diverse cells; however, PrP^C may be released from cells by ADAM proteases or when packaged into extracellular vesicles (EVs). In this study, we show that a soluble derivative of PrP^C (S-PrP) counteracts inflammatory responses triggered by pattern recognition receptors in macrophages, including TLR2, TLR4, TLR7, TLR9, NOD1, and NOD2. S-PrP also significantly attenuates the toxicity of LPS in mice. The response of macrophages to S-PrP is mediated by a receptor assembly that includes the N-methyl-d-aspartate receptor (NMDA-R) and low-density lipoprotein receptor-related protein-1 (LRP1). PrP^C was identified in EVs isolated from human plasma. These EVs replicated the activity of S-PrP, inhibiting cytokine expression and IκBα phosphorylation in LPS-treated macrophages. The effects of plasma EVs on LPS-treated macrophages were blocked by PrP^C-specific Ab, by antagonists of LRP1 and the NMDA-R, by deleting Lrp1 in macrophages, and by inhibiting Src family kinases. Phosphatidylinositol-specific phospholipase C dissociated the LPS-regulatory activity from EVs, rendering the EVs inactive as LPS inhibitors. The LPS-regulatory activity that was lost from phosphatidylinositol-specific phospholipase C-treated EVs was recovered in solution. Collectively, these results demonstrate that GPI-anchored PrP^C is the essential EV component required for the observed immune regulatory activity of human plasma EVs. S-PrP and EV-associated PrP^C regulate innate immunity by engaging the NMDA-R/LRP1 receptor system in macrophages. The scope of pattern recognition receptors antagonized by S-PrP suggests that released forms of PrP^C may have broad anti-inflammatory activity.

SUBMITTER: Mantuano E

PROVIDER: S-EPMC8702456 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature

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A Soluble PrPC Derivative and Membrane-Anchored PrPC in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

Mantuano Elisabetta E Azmoon Pardis P Banki Michael A MA Sigurdson Christina J CJ Campana Wendy M WM Gonias Steven L SL

Journal of immunology (Baltimore, Md. : 1950) 20211122 1

Nonpathogenic cellular prion protein (PrPC) demonstrates anti-inflammatory activity; however, the responsible mechanisms are incompletely defined. PrPC exists as a GPI-anchored membrane protein in diverse cells; however, PrPC may be released from cells by ADAM proteases or when packaged into extracellular vesicles (EVs). In this study, we show that a soluble derivative of PrPC (S-PrP) counteracts inflammatory responses triggered by pattern recognition ...[more]

PMID: 34810220

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Project description:Prion diseases are fatal neurodegenerative diseases in mammals with the unique characteristics of misfolding and aggregation of the cellular prion protein (PrPC) to the scrapie prion (PrPSc). Although neuroinflammation and neuronal loss feature within the disease process, the details of PrPC/PrPSc molecular transition to generate different aggregated species, and the correlation between each species and sequence of cellular events in disease pathogenesis are not fully understood. In this study, using mice inoculated with the RML isolate of mouse-adapted scrapie as a model, we applied asymmetric flow field-flow fractionation to monitor PrPC and PrPSc particle sizes and we also measured seeding activity and resistance to proteases. For cellular analysis in brain tissue, we measured inflammatory markers and synaptic damage, and used the isotropic fractionator to measure neuronal loss; these techniques were applied at different timepoints in a cross-sectional study of disease progression. Our analyses align with previous reports defining significant decreases in PrPC levels at pre-clinical stages of the disease and demonstrate that these decreases become significant before neuronal loss. We also identified the earliest PrPSc assemblies at a timepoint equivalent to 40% elapsed time for the disease incubation period; we propose that these assemblies, mostly composed of proteinase K (PK)-sensitive species, play an important role in triggering disease pathogenesis. Lastly, we show that the PK-resistant assemblies of PrPSc that appear at timepoints close to the terminal stage have similar biophysical characteristics, and hence that preparative use of PK-digestion selects for this specific subpopulation. In sum, our data argue that qualitative, as well as quantitative, changes in PrP conformers occur at the midpoint of subclinical phase; these changes affect quaternary structure and may occur at the threshold where adaptive responses become inadequate to deal with pathogenic processes.

Project description:BackgroundThe N-methyl-D-aspartate receptors are key mediators of excitatory transmission and are implicated in many forms of synaptic plasticity. These receptors are heterotetrameres consisting of two obligatory NR1 and two regulatory subunits, usually NR2A or NR2B. The NR2B subunits are abundant in the early postnatal brain, while the NR2A/NR2B ratio increases during early postnatal development. This shift is driven by NMDA receptor activity. A functional interplay of the Low Density Lipoprotein Receptor Related Protein 1 (LRP1) NMDA receptor has already been reported. Such abilities as interaction of LRP1 with NMDA receptor subunits or its important role in tPa-mediated NMDA receptor signaling were already demonstrated. Moreover, mice harboring a conditional neuronal knock-out mutation of the entire Lrp1 gene display NMDA-associated behavioral changes. However, the exact role of LRP1 on NMDA receptor function remains still elusive.ResultsTo provide a mechanistic explanation for such effects we investigated whether an inactivating knock-in mutation into the NPxY2 motif of LRP1 might influence the cell surface expression of LRP1 and NMDA receptors in primary cortical neurons. Here we demonstrate that a knock-in into the NPxY2 motif of LRP1 results in an increased surface expression of LRP1 and NR2B NMDA receptor subunit due to reduced endocytosis rates of LRP1 and the NR2B subunit in primary neurons derived from LRP1ΔNPxY2 animals. Furthermore, we demonstrate an altered phosphorylation pattern of S1480 and Y1472 in the NR2B subunit at the surface of LRP1ΔNPxY2 neurons, while the respective kinases Fyn and casein kinase II are not differently regulated compared with wild type controls. Performing co-immunoprecipitation experiments we demonstrate that binding of LRP1 to NR2B might be linked by PSD95, is phosphorylation dependent and this regulation mechanism is impaired in LRP1ΔNPxY2 neurons. Finally, we demonstrate hyperactivity and changes in spatial and reversal learning in LRP1ΔNPxY2 mice, confirming the mechanistic interaction in a physiological readout.ConclusionsIn summary, our data demonstrate that LRP1 plays a critical role in the regulation of NR2B expression at the cell surface and may provide a mechanistic explanation for the behavioral abnormalities detected in neuronal LRP1 knock-out animals reported earlier.

Dataset Information

A Soluble PrP^C Derivative and Membrane-Anchored PrP^C in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

Publications

A Soluble PrP<sup>C</sup> Derivative and Membrane-Anchored PrP<sup>C</sup> in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

A Soluble PrPC Derivative and Membrane-Anchored PrPC in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

Publications

A Soluble PrP&lt;sup&gt;C&lt;/sup&gt; Derivative and Membrane-Anchored PrP&lt;sup&gt;C&lt;/sup&gt; in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

A Soluble PrP^C Derivative and Membrane-Anchored PrP^C in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.

A Soluble PrP<sup>C</sup> Derivative and Membrane-Anchored PrP<sup>C</sup> in Extracellular Vesicles Attenuate Innate Immunity by Engaging the NMDA-R/LRP1 Receptor Complex.