Interestingly, up to 37 genes involved in the immune system response, such as CCR1, CX3CR1, TLR1 and TLR7, were found to be up-regulated in advanced lesion [see Additional file 5], which might suggest that these immune/inflammatory related genes could serve as expression signatures characterizing different stages of PAD. This evidence concerns the gene CX3CR1 and peripheral arterial disease.