Although the findings of this study are the first to demonstrate increased expression of NONMMUT0013718 and Id2 in macrophages but not endothelial cells infected in vitro, it remains to be determined whether changes in the lungs during in vivo Rickettsia infection are due to increased transcription within target host cells, increased recruitment of inflammatory cells, or possibly a combinatorial effect of both. Here, ID2 is linked to Rickettsiosis.