  Atherosclerosis occurs when plaque clogs the arteries. It is a leading cause
of death in the United States and worldwide. In this paper, we study the
bifurcation for a highly nonlinear and highly coupled PDE model of plaque
formation in the early stage of atherosclerosis. The model involves LDL and HDL
cholesterols, macrophage cells as well as foam cells, with the interface
separating the plaque and blood flow region being a free boundary. We establish
the first bifurcation point for the system corresponding to $n=1$ mode. The
symmetry-breaking stationary solution studied in this paper might be helpful in
understanding why there exists arterial plaque that is often accumulated more
on one side of the artery than the other.
