MMP9 and infection: In our study, in comparison to intracellular infection, which induced a modest pro-inflammatory response as reported by others (Tuchscherr et al., 2011; Tan et al., 2014), extracellular infection induced manifest changes in gene expression of pro-immune factors (such as CSF2, CXCL8) and of tissue remodeling factors (such as MMP1, MMP9) as expected (Wang et al., 2010).