Substance P: An immunohistochemical and biochemical study in human gingival tissues. A role for neurogenic inflammation?
In this study, researchers aimed to determine whether the neuropeptide substance P could be detected in human gingiva and whether its effect on gingival fibroblasts could indicate a potential role for neurogenic inflammation in the periodontal disease. They took healthy human gingival tissue and inflamed gingival specimens during periodontal surgery. These tissues were fixed and stained to confirm inflammatory status of the tissues. Immunohistochemical staining was done, and polyclonal rabbit anti-substance P in human gingival tissue was used. The effect of substance P on gingival fibroblast DNA synthesis was also measured in various media concentrations of Dulbecco's odification of eagle's medium (DMEM) and fetal calf serum (FCS) with or without substance P. Protein and proteoglycan synthesis by gingival fibroblasts was assessed in varying concentrations of substance P.
The results revealed that in healthy gingiva the antibody localized in the connective tissue, specifically within the rete peg region, as well as around blood vessels. In inflamed tissue the distribution was similar to the normal tissues with the fibrous networks and extravascular distributions as well as localizing specifically to the inflammatory foci. The distribution in inflamed tissues was notable in that it appeared to be closely associated with cell infiltrates. When the cells were exposed to substance P in media containing 0% FCS, there was little detectable DNA synthesis. At 0.2% FCS there was a significant increase in DNA synthesis. In the presence of substance P and 0.2% FCS, maximum stimulation was noted at 10-9 M and was found to approach levels noted for cells exposed to 10% FCS. The amount of proteoglycan and total protein released into the culture by the cells exposed to substance P did not differ significantly from the controls, although the cells exposed to substance P appeared to retain more material within the cell layer.
This study has demonstrated the presence of substance P in normal and inflamed human gingiva as well as the ability of substance P to influence human gingival fibroblast proliferative and synthetic activity. The immunohistochemical localization of substance P in gingival tissues implicates it as a potential mediator of inflammation. [M.C.R.]
Bartold, P.M., A. Kylstra, and R. Lawson, J Periodont, 65:1113,1994