The role of blood-brain barrier TJ proteins in neuroinflammtion
In neurological disorders such as MS and stroke, barrier characteristics of the blood-brain barrier (BBB) are lost. Recent data from partner 5 suggest that stabilizing claudin expression at the BBB during experimental autoimmune encephalomyelitis (EAE), an animal model for MS, reduces BBB permeability and ameliorates the disease. Thus, therapeutic sealing of BBB endothelial cell-cell junctions represents an attractive alternative for restoring BBB function and eventually CNS homeostasis.
The challenges faced for developing such methods include our present lack of in-depth knowledge of the precise molecular architecture of BBB tight junctions (TJs) and our incomplete understanding of how the individual TJ components function and are regulated and how they are expressed in the BBB. In contrast to claudin-5, the functions of other TJ proteins including claudins or members of the Ig superfamily and others expressed at the BBB, remain unknown to date.
Using novel transgenic mouse models with inducible or constitutive lack of these junctional proteins in the BBB partner 5 will investigate the expression and function of these molecules in maintaining TJ integrity of the BBB and how they influence the migration of different immune cell subsets across the BBB under physiological flow in vitro, employing established in vitro BBB models and in vivo using animal models of MS and stroke. Stroke models are available through collaboration with partner 1. Functional approaches to studying BBB function in vitro, e.g. impedance and permeability, will be accompanied by in vivo investigations of BBB integrity; here diffusion of injected tracers across the BBB will be assessed by means of live cell imaging (2-photon microscopy) and mesoscopic 3D-imaging to elucidate disease pathology in EAE and stroke models. These techniques will be available for other partner, e.g. partner 1. Fluorescently labelled immune cell subsets will be traced by live cell imaging. Depending on the results, transcriptome analyses of the different BBB models or CNS microvessels will be performed to identify novel targets for elevating BBB function.
- Lena Wyss, Julia Schäfer, Stefan Liebner, Michel Mittelbronn, Urban Deutsch, Gaby Enzmann, Ralf H. Adams, Michel Aurrand-Lions, Karl H. Plate, Beat A. Imhof, Britta Engelhardt. (2012) Junctional adhesion molecule (JAM)-C deficient C57BL/6 mice develop a severe hydrocephalus. PLoSOne 7(9):e45619. doi: 10.1371
- Pfeiffer F, Schäfer J, Lyck R, Makrides V, Brunner S, Schaeren-Wiemers N, Deutsch U and B Engelhardt. (2011) Claudin-1 induced sealing of blood-brain barrier tight junctions ameliorates chronic experimental autoimmune encephalomyelitis. Acta Neuropathol 122: 601-614
- Coisne Caroline, Ruth Lyck and Britta Engelhardt. 2013. Live cell imaging techniques to study T cell trafficking across the blood-brain barrier in vitro and in vivo. Fluids and Barriers of the CNS 10:7 doi:10.1186/2045-8118-10-7; 21 January 2013
Tasks and methodology
- In vitro BBB models
- In vivo investigations of BBB integrity including 2P intravital microscopy of the diffusion of injected tracers across the BBB
- Mesoscopic imaging of BBB integrity
- In vitro and in vivo live cell imaging to trace fluorescently labelled immune cells
- Transcriptome analysis
University of Luebeck, Cell specific gene deletion in brain endothelium, 7 month