Porphyromonas gingivalis conditioned medium induces amyloidogenic processing of the amyloid-β protein precursor upon in vitro infection of sh-sy5y cells

Kanagasingam, Shalini, von Ruhland, Christopher, Welbury, Richard, Chukkapalli, Sasanka S. and Singhrao, Sim K. 2022. Porphyromonas gingivalis conditioned medium induces amyloidogenic processing of the amyloid-β protein precursor upon in vitro infection of sh-sy5y cells. Journal of Alzheimer's Disease Reports 6 (1) , pp. 577-587. 10.3233/ADR-220029

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Abstract

Background: Cleavage of the amyloid-β protein precursor (AβPP) mediated by host secretase enzymes, releases several fragments including amyloid-β (Aβ40 and Aβ42). Objective: To determine if Porphyromonas gingivalis conditioned medium cleaved AβPP to release Aβ40 and Aβ42. Methods: The SH-SY5Y cell line was challenged, in vitro, with P. gingivalis (Pg381) conditioned medium in the presence/absence of cytokines. The cells and their supernatants were assessed for AβPP cleavage fragments by immunoblotting and transmission electron microscopy. Results: Western blotting of the cell lysates with the anti-AβPP C-terminal antibody demonstrated variable molecular weight bands corresponding to full length and fragmented AβPP in lanes treated with the following factors: Tryptic soy broth (TSB), Pg381, IL-6, Pg381 + IL-1β, and Pg381 + TNF-α. The low molecular weight bands corresponding to the C99 dimerized fragment were observed in the Pg381 and interlukin-6 (IL-6) treated groups and were significantly more intense in the presence of Pg381 with either IL-6 or TNF-α. Bands corresponding to the dimerized C83 fragment were observed with cells treated with TNF-α alone and with Pg381 combined with IL-1β or IL-6 or TNF-α. The anti-Aβ antibody detected statistically significant Aβ40 and Aβ42, levels when these two Aβ species were pooled across test samples and compared to the untreated group. Electron microscopic examination of the supernatants demonstrated insoluble Aβ40 and Aβ42. Conclusion: These observations strongly imply that AβPP is an infection responsive protein cleaved via the amyloidogenic pathway on exposure to conditioned medium and in the presence of pro-inflammatory mediators.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Medicine
Publisher:	IOS Press
ISSN:	2542-4823
Date of First Compliant Deposit:	11 November 2022
Date of Acceptance:	23 August 2022
Last Modified:	14 May 2023 02:15
URI:	https://orca.cardiff.ac.uk/id/eprint/154129

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