TGFB1 and periodontitis: Their results indicate that Porphyromonasgingivalis is a major contributor to the altered immune responses and pathology of periodontitis.14 As TGF-β has been implicated in differentially regulated gene expression in gingival fibroblasts, Ohshima et al15 hypothesized that TGF-β signaling would be activated in periodontitis-affected gingiva, along with enhanced collagen degradation.