An Investigation into the Effects of Outer Membrane Vesicles and Lipopolysaccharide of Porphyromonas gingivalis on Blood-Brain Barrier Integrity, Permeability, and Disruption of Scaffolding Proteins in a Human in vitro Model

Article type: Research Article

Authors: Pritchard, Anna Barlach^{a; *} | Fabian, Zsolt^b | Lawrence, Clare L.^c | Morton, Glyn^d | Crean, StJohn^a | Alder, Jane E.^c

Affiliations: [a] Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK | [b] School of Medicine, University of Central Lancashire, Preston, UK | [c] Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK | [d] School of Forensic and Investigative Science, University of Central Lancashire, Preston, UK

Correspondence: [*] Correspondence to: Anna Barlach Pritchard, Brain and Behaviour Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK. Tel.: +44 0 1772 895906; E-mail: [email protected].

Abstract: Background:The effects of the key pathogens and virulence factors associated with gum disease such as Porphyromonas gingivalis (P. gingivalis) on the central nervous system is of great interest with respect to development of neuropathologies and hence therapeutics and preventative strategies. Chronic infections and associated inflammation are known to weaken the first line of defense for the brain, the blood-brain barrier (BBB). Objective:The focus of this study is to utilize an established human in vitro BBB model to evaluate the effects of P. gingivalis virulence factors lipopolysaccharide (LPS) and outer membrane vesicles (OMVs) on a primary-derived human model representing the neurovascular unit of the BBB. Methods:Changes to the integrity of the BBB after application of P. gingivalis LPS and OMVs were investigated and correlated with transport of LPS. Additionally, the effect of P. gingivalis LPS and OMVs on human brain microvascular endothelial cells in monolayer was evaluated using immunofluorescence microscopy. Results:The integrity of the BBB model was weakened by application of P. gingivalis LPS and OMVs, as measured by a decrease in electrical resistance and a recovery deficit was seen in comparison to the controls. Application of P. gingivalis OMVs to a monoculture of human brain microvascular endothelial cells showed disruption of the tight junction zona occludens protein (ZO-1) compared to controls. Conclusion:These findings show that the integrity of tight junctions of the human BBB could be weakened by association with P. gingivalis virulence factors LPS and OMVs containing proteolytic enzymes (gingipains).

Keywords: Alzheimer’s disease, blood-brain barrier, human brain microvascular endothelial cells, in vitro BBB model, microbiome, periodontal disease

DOI: 10.3233/JAD-215054

Journal: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 343-364, 2022