Interleukin-4 released from human gingival fibroblasts reduces osteoclastogenesis. (December 2016)

• Record Type: Journal Article
• Authors: Ujiie, Yuko; Karakida, Takeo; Yamakoshi, Yasuo; Ohshima, Tomoko; Gomi, Kazuhiro; Oida, Shinichiro
• Is Part Of: Archives of oral biology. Volume 72(2016)
• Page Start: 187
• Page End: 193
• Publication Date: 2016-12
• Subjects: Interleukin-4 -- RANKL -- Osteoprotegerin -- Human gingival fibroblasts; Mouth -- Periodicals; Mouth -- Diseases -- Periodicals; Dentistry -- Periodicals; Electronic journals; 617.6005
• DOI: 10.1016/j.archoralbio.2016.08.024
• Languages: English
• ISSNs: 0003-9969

Abstract

Highlights: Conditioning medium of human gingival fibroblasts (hGF-CM) decreased TRAP staining of stimulated RAW264 cells in a dose-dependent manner. The gene expression of IL-4 and Osteoprotegerin (OPG) was observed in hGF-CM as osteoclastogenesis inhibitory factors. IL-4 released from hGF showed differential inhibition of osteoclasts. Abstract: Objective: Human gingival epithelium is continuously exposed to bacteria and acts as the first line of defense in periodontal tissues. It is crucial to maintain healthy, non-inflamed gingival tissue to avoid gingivitis and periodontitis. The purpose of this study was to investigate the influence of IL-4 in human gingival fibroblasts (hGF) on the activation of osteoclasts. Design: Two hGF samples were obtained from two healthy patients, and one was collected from a commercially available resource. The hGFs were cultured, and conditioned medium of hGF (hGF-CM) was stocked at −80 °C. The mRNA was isolated from the hGF cultures and analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) for expression of suppressive osteoclastogenetic mediators, such as interleukin (IL)-4, osteoprotegerin (OPG), IL-10, IL-27, and IL-33. The hGF-CM was used to investigate the inhibitory function of mouse macrophages supplemented with either glutathione S-transferase-Receptor activator of NF-kB ligand (GST-RANKL), human recombinant (rh)IL-4, or rhOPG but not a combination. Differentiation of osteoclasts was examined by tartrate resistant acid phosphatase (TRAP) staining and TRAP assay. The suppressive role of IL-4 was assessed by neutralizing IL-4 antibody in the TRAP assay. Results: The hGF-CM reduced both TRAP positive staining and activity in a dose-dependent manner. IL-4 and OPG mRNA expressions were expressed in hGF-CM from three different donors but that of IL-10, IL-27, or IL-33 was not detected. In the RAW264 culture, rhIL-4 and rhOPG reduced TRAP positive staining as well as activity in a dose-dependent manner. Moreover, addition of neutralizing antibodies for IL-4 reduced the inhibitory effect of conditioned medium from gingival fibroblasts in the RAW264 culture. Conclusion: We concluded that hGF potentially contained suppressive mediators, such as IL-4 and OPG, for osteoclastogenesis. Moreover, we confirmed that the differential inhibition of osteoclast is caused by OPG as well as IL-4 in hGF-CM.