Abstract
Purpose: :
Complement factor H (CFH) polymorphisms are the strongest genetic risk factors associated with age-related macular degeneration (AMD). How this gene confers risk of AMD is not clear. Mouse cfh protein shares only partial homology to its human counterpart. To facilitate the study of the role of CFH in animal models, we generated bacterial artificial chromosome (BAC) transgenic mouse lines carrying human CFH variants. We also examined whether human CFH can functionally replace mouse cfh in the mouse complement alternative pathway.
Methods: :
BAC clones spanning the entire human CFH gene (either the normal Y402 or the "at-risk" H402 variant) were used to generate transgenic mice. Positive founder lines were established and back-crossed to C57BL/6 as well as cfh null (cfh-/-) mice. We characterized the transgenic mice on the cfh-/- background (CFH402Y, cfh-/- and CFH402H, cfh-/-). The pattern of tissue expression was explored using quantitative real-time PCR. The presence of CFH402Y and CFH402H in plasma was confirmed by MALDI-TOF-TOF and analyzed semi-quantitatively on Western blots. The function of human CFH in the mouse complement alternative pathway was investigated using Western blots and using a C3 hemolysis assay. Retina morphology was assessed on semi-thin plastic sections.
Results: :
We successfully generated three lines that carry the human CFH gene (two H402 and one Y402 variants). For all three lines, the human CFH mRNA is expressed in the liver at the highest levels, and at moderate levels in the brain and eye. Human CFH protein was identified in the plasma. In the absence of mouse cfh, the human CFH can inhibit the cleavage of mouse C3 to C3b and increase the amount of functional C3 in the mouse plasma. Initial analysis on young adult transgenic mouse retinas did not yield morphological abnormalities.
Conclusions: :
Humanized CFH transgenic mice are phenotypically similar to wild type mice and the human CFH protein can replace mouse cfh in the mouse complement alternative pathway.
Keywords: age-related macular degeneration • transgenics/knock-outs • immunomodulation/immunoregulation