ABSTRACT
The accumulation of amyloid-ß (Aß) in the walls of capillaries and arteries as cerebral amyloid angiopathy (CAA) is part of the small vessel disease spectrum, related to a failure of elimination of Aß from the brain. Aß is eliminated along basement membranes in walls of cerebral capillaries and arteries (Intramural Peri-Arterial Drainage-IPAD), a pathway that fails with age and ApolipoproteinEε4 (ApoE4) genotype. IPAD is along basement membranes formed by capillary endothelial cells and surrounding astrocytes. Here, we examine (1) the composition of basement membranes synthesised by ApoE4 astrocytes; (2) structural differences between ApoE4 and ApoE3 astrocytes, and (3) how flow of Aß affects Apo3/4 astrocytes. Using cultured astrocytes expressing ApoE3 or ApoE4, immunofluorescence, confocal, correlative light and electron microscopy (CLEM), and a millifluidic flow system, we show that ApoE4 astrocytes synthesise more fibronectin, possess smaller processes, and become rarefied when Aß flows over them, as compared to ApoE3 astrocytes. Our results suggest that basement membranes synthesised by ApoE4 astrocytes favour the aggregation of Aß, its reduced clearance via IPAD, thus promoting cerebral amyloid angiopathy.
Subject(s)
Apolipoproteins E/metabolism , Astrocytes/metabolism , Basement Membrane/metabolism , Fibronectins/metabolism , Laminin/metabolism , Alternative Splicing , Amyloid beta-Peptides/metabolism , Apolipoprotein E3/metabolism , Apolipoprotein E4/metabolism , Astrocytes/cytology , Cells, Cultured , Fluorescent Antibody Technique , Humans , Microscopy, Confocal , Microscopy, ElectronABSTRACT
INTRODUCTION: Between 3 and 18% of craniofacial osteosynthesis plates are removed due to chronic infection. Removal of the plate is necessary to manage the chronic infective state i.e. miniplate removal results in resolution of the infection. These observations are suggestive of a biofilm-related infection. The aim of this retrospective study was to characterise the presence of biofilm on the removed miniplates from oral and maxillofacial surgery. MATERIALS AND METHODS: A total of 12 plates and associated screws were recovered from eleven patients suffering from persistent, trauma site infection. The recovered plates plus 1 control plate were imaged using scanning electron microscopy (SEM). One recovered plate was also imaged using confocal microscopy (CM) for comparative purposes. RESULTS: Of the 12 plates, 3 (25%) demonstrated highly localised polymicrobial biofilms, five (42%) demonstrated coccal biofilms, one possessed a filamentous biofilm and one showed attached yeast. Overall, 75% of the plates and 82% of the patients exhibited evidence of biofilm to varying degrees. All of the infections resolved following removal of the plates and antibiotic treatment. CONCLUSION: Microbial biofilms can explain the clinical course of chronic infections associated with miniplates.
