Healthy and Inflamed Gingival Fibroblasts Differ in Their Inflammatory Response to Porphyromonas gingivalis Lipopolysaccharide.

Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) can induce the host immune response in periodontitis patients. Human gingival fibroblasts (GFs) play an important role in regulating the host immune response in periodontitis. However, whether GFs isolated from healthy subjects (HGFs) and inflamed ones (IGFs) can modulate different inflammatory response remains problematic. The aim of this study was to investigate the expression of different inflammatory cytokines between HGFs and IGFs after P. gingivalis LPS stimulation. In this study, hematoxylin and eosin (H&E) staining was used to assess the inflammation status of gingiva. HGFs and IGFs were stimulated with 1, 5, and 10 μg/ml P. gingivalis LPS for 6, 12, and 24 h. The amount of inflammatory cytokines, interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor (TNF)-α, was determined by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). The results showed that gingiva from periodontitis patients presented epithelial hyperkeratosis and abundant inflamed cells in the connective tissue. HGFs participated in the overproduction of IL-8 and IL-1β in a dose- and time-dependent manner; however, IL-6 and TNF-α just showed a dose-response change when stimulated with LPS after 24 h. In IGFs, IL-6, IL-8, IL-1β, and TNF-α could be induced by lower LPS with shorter time stimulation and the dose-response phenomenon was observed in mRNA levels. In conclusion, the resident IGFs do not exhibit LPS tolerance and play an important role in modulating host immune response, which are critical in the immunopathogenesis of periodontal disease.