Immunohistochemical localization and expression of fibromodulin in adult rat periodontium and inflamed human gingiva

Objective: The aim of this study was to determine the distribution and expression of fibromodulin in rat periodontium and inflamed human gingiva. Methods: The distribution of fibromodulin in rat periodontium and human gingiva was studied by immunohistochemistry. The expression of fibromodulin mRNA from human periodontal cells was studied by reverse transcription-polymerase chain reaction. The distribution and mRNA expression of collagen types I and III as well as proteoglycans (decorin and biglycan) were also studied. Results: In the rat periodontium, fibromodulin was distributed in the fibroblasts as well as their extracellular matrices. Strong expression was noted in the interfaces of periodontal ligament with alveolar bone and cementum. In human gingival tissues, staining of fibromodulin was detected in the connective tissue of inflamed gingiva associated with gingivitis and periodontitis; whereas, weak staining was noted in healthy gingival tissues. The expression of fibromodulin mRNA was strongest in the cultured osteoblasts. Conclusions: Fibromodulin is differentially expressed throughout the periodontium being primarily associated with collagen type I in non-mineralized sites. Fibromodulin showed an upregulation in inflamed gingiva. Supported by a Fellowship from NHMRC of Australia ID199925 and an Early career Research Grant from the University of Queensland.