In vivo experimental model of human gingival mucosa using immunodeficient mice

Human β-defensin-2 and interleukin-1β expression in response to Porphyromonas gingivalis challenge in mice transplanted with periodontitic human gingiva

Inter-individual variability in the host response contributes significantly to expression of periodontal disease. Thus, research into the human host response is considered important in the analysis of periodontal disease. Human β-defensin-2 (hBD-2) is typically produced by epithelial tissues after stimulation with microorganisms and inflammatory mediators, and it contributes to the initial defense in the innate immune response. However, hBD-2 expression in response to infection has not been investigated in human gingival tissue with periodontitis. We examined the response to Porphyromonas gingivalis in an established in vivo model of human gingival grafts with various degrees of periodontitis. We also investigated the expression profile of interleukin-1β (IL-1β). Gingival tissues were collected from 40 patients with chronic periodontitis (21 with slight-to-moderate disease, 19 with severe disease) during tooth extraction or periodontal surgery. These tissues were transplanted subcutaneously into nu/nu mice. We used real-time PCR to compare the expression of hBD-2 and IL-1β. In slight-to-moderate chronic periodontitis, hBD-2 expression was significantly higher in the stimulated group than in the non-stimulated group (p < 0.05), but there was no significant increase in the group with severe chronic periodontitis. IL-1β expression did not differ between groups. Increased expression of hBD-2 and IL-1β was associated with slight-to-moderate periodontitis (p < 0.05), and there was a significant relationship between decreased hBD-2 and IL-1β expression and severe periodontitis (p < 0.05). The initial expression profile of hBD-2 in P. gingivalis infection differs according to the severity of periodontitis. In addition, changes in hBD-2 and IL-1β expression may be important in the progression of periodontitis.

Induction of β-Defensin Expression by Porphyromonas gingivalis-Infected Human Gingival Graft Transplanted in nu/nu Mouse Subdermis

It is important to understand the onset of periodontal disease in terms of bacterial infection and host factors. Host-bacteria interactions can be elicited in human cultured cells and animal models, but these models provide only limited biological information about human host reactions against bacterial attacks. Development of an in vivo model using human gingival tissue is needed. We established an in vivo model using nu/nu mice and evaluated host defense following bacterial infection in human gingiva. Human gingival samples were collected from periodontitis patients and transplanted in nu/nu mouse subdermis. After 2 weeks, human characteristics were confirmed by positive immunohistochemical reactions for human-specific markers. We used this model to investigate human β-defensin-2 (hBD-2), an antimicrobial peptide that contributes to initial defense against bacterial invasion. Using real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry, we investigated whether hBD-2 expression was induced in human gingiva as a response to Porphyromonas gingivalis as a periodontal pathogen. Two hours after infection with bacteria, we detected increased expression of hBD-2 mRNA, which was localized in the epithelium of human gingiva. Using our in vivo model, we concluded that increased hBD-2 may play an important role in early defense from bacterial infection in human gingival epithelium.