ACE and gingivitis: AGT, renin, ACE-2, AT1R and the MasR each had low mRNA expression with no differences among constitutive cells or cells challenged with LPS from P. gingivalis or E. coli. ACE was the only target that was significantly more expressed in gingival fibroblasts compared to periodontal ligament cells regardless of the group tested, further supporting the hypothesis that RAS may be involved in the progression of gingivitis rather then the maintenance.