The murine Lyme arthritis-associated mmp9 was also significantly upregulated in the dura mater of infected mice at day 7 post-infection [14,44,45]; however, the magnitude of expression change did not reach our fold-change cut-off for differential expression calling (padj = 0.003; Fold-change = 1.3; DEG cut-off = 1.5). This evidence concerns the gene MMP9 and infection.