5α-reductase activity in human gingiva and gingival fibroblasts in response to bacterial culture supernatants, using [14C]4-androstenedione as substrate

5α-Reduction of androgen substrates is increased in inflamed gingiva. It was therefore relevant to study the effect of bacterial culture supernatants derived from Prevotella intermedius (P.i), Porphyromonas gingivalis (P.g) and Actinobacillus actinomycetemcomitans(A.a) on the metabolism of [14C]4androstenedione to 5α-dihydrotestosterone (DHT) in gingival tissue and cultured fibroblasts. Chronically inflamed human gingival tissue and cultured gingival fibroblasts from the same source were incubated in duplicate with [14C]4-androstenedione and optimal concentrations of P.i, P.g and A.a culture supernatants in Eagleʹs minimal essential medium in a Co2 incubator for 24 h at 37°C. The metabolites were then extracted, separated and quantified using a radioisotope scanner. There were 87, 50 and 6% increases in DHT synthesis by human gingival tissue in response to the culture supernatants of P.i, P.g and A.a, respectively, over control incubations (n = 3; p < 0.01: Wilcoxon signed-rank statistic for paired observations). With the cells in culture, all four fibroblast cell lines produced DHT and testosterone from [14C]4-androstenedione in varying amounts. The production of DHT was enhanced in the presence of each of the bacterial culture supernatants to varying degrees (P.i 40%, P.g 35% and A.a 40%; p < 0.01). Combinations of the bacterial extracts: (P.i + Rg), (P.i + A.a), (P.g + A.a) and (P.i + P.g + A.a), showed intermediate or suppressor effects on DHT formed compared with individual incubations. Culture supernatants of these pathogens can influence DHT synthesis in fibroblasts, an effect that is modulated by baseline androgen metabolism and the proportion of virulent pathogens present. This may have some bearing on host susceptibility and the progression of the periodontal lesion.