Abstracts (complete list) - Wissenschaft Online

Johannes Stephani, Ronald Naumann, Hermann Wagner, Tim Sparwasser
Generation of TLR- „humanized“ Mice with Bacterial Artificial
Chromosome-Technology
”Humanized“ transgenic mice expressing human pattern recognition receptors
specifically on DCs are urgently needed to develop small animal models for testing new
vaccination strategies, since significant immunologic differences limit the interpretation
of data obtained from mouse experiments. In comparison to mice, human Toll-like
receptor 9 (TLR9) has a different ligand specificity and is expressed on different immune
cells. In mice, TLR9 recognizes unmethylated CpG DNA and is expressed on
conventional dendritic cells (cDCs), plasmacytoid dendritic cells (pDCs) and B cells. In
humans, TLR9 is only detectable on pDCs and B cells and mediates immune cell
activation by slightly different CpG sequences. We attempted to generate a mouse
model mimicking human TLR9 expression by transgenesis of a Bacterial Artificial
Chromosome (BAC) containing human TLR9 together with all its cis- and transregulatory
regions. The purified and linearized BAC has been injected into pronuclei of
fertilized C57BL/6 mouse eggs, and human BAC-transgenic mice were generated. Two
BAC transgenic founder mice were obtained which are currently backcrossed to a
murine TLR9 deficient background. First preliminary immunization data with “human”
CpG sequences may suggest that the human promoter is functional in mice. Currently
we are analyzing the expression level and specificity of human TLR9 in mice. This
mouse model may provide us with new valuable tools to directly examine the role of
human TLR9 on plasmacytoid DCs and B cells in vaccination studies and may allow us to
test the therapeutical potential of CpG oligonucleotides in various diseases such as
infection, allergy and tumor models.