Glia 2001 Dec;36(3):414-420
Wolf SA, Gimsa U, Bechmann I, Nitsch
R.
Department of Cell and Neurobiology,
Institute of Anatomy, Humboldt University Hospital Charite, Berlin, Germany.
Autoreactive T-cells are involved in demyelination, neurodegeneration, and the recruitment of peripheral macrophages and nonspecific activated T-cells in autoimmune diseases such as multiple sclerosis (MS).
The ligation of costimulatory B7 molecules on microglia with CD28/CTLA-4 on T-cells is thought to be crucial to the onset and course of MS and its rodent model experimental autoimmune encephalomyelitis (EAE).
It is currently unclear as to how far the nature of infiltrating T-cells has an impact on the expression of the B7 molecules on microglia, the resident antigen-presenting cells (APCs) of the brain.
We studied the expression of B7-1 and B7-2 on microglia after encounter with preactivated Th1 and Th2 cells from transgenic mice whose T-cells express a receptor (TCR) either specific to myelin basic protein (MBP) or ovalbumin (OVA) using murine organotypic entorhinal-hippocampal slice cultures (OEHSC).
Our main finding was that Th1 cells downregulate the constitutive expression of B7-2 and induce B7-1 expression while Th2 cells do not induce this B7-1 upregulation.
The main difference between MBP- and OVA-specific cells was seen in experiments were Th1 cells had direct contact to APCs but not to brain tissue. In contrast to MBP-specific Th1 cells, OVA-specific Th1 cells required the addition of antigen to upregulate B7-1 and downregulate B7-2.
When the cells were allowed to have contact to brain tissue, no difference was seen in the pattern of B7 regulation between OVA- and MBP-specific T-cells.
Our data suggest that T-cells are
able to modulate B7 expression on microglial cells in the brain independent
of antigen presentation through TCR/MHC-II ligation but presumably by soluble
mediators.
PMID: 11746777 [PubMed - as supplied
by publisher]
Copyright 2001 Wiley-Liss, Inc.