Importin 8 is involved in human periodontitis by the NF-κB pathway

This study was undertaken to investigate the roles of importin 8 (IPO8) and infiltrating macrophages in human periodontitis. Gingival tissues were collected from 18 male patients with mild and severe periodontitis. IPO8 expression was observed by immunohistochemistry and western blotting. CD68 expression, a marker for macrophages, was observed by immunohistochemistry and immunofluorescence. IPO8 expression in mouse macrophage RAW264.7 cells stimulated by lipopolysaccharide (LPS) purified from Porphyromonas gingivalis was examined in vitro using small interfering RNA (siRNA). Phosphorylation of nuclear factor kappa B (NF)-κB pp65 was detected as an indicator of NF-κB activation by immunofluorescence and western blotting. IPO8 expression was increased in gingival tissues with periodontitis compared with healthy ones, and the elevation rose in proportion to the severity of periodontitis. Similarly, more CD68+ infiltrating macrophages were observed in severe periodontitis tissues. LPS stimulation promoted IPO8 expression in mouse macrophage cells. Knockdown of IPO8 by siRNA alleviated the LPS-induced increases in tumor necrosis factor-α and interleukin-6 gene expression, as well as NF-κB activation, by decreasing the expression of NF-κB pp 65 in the nuclei of cells in vitro. In conclusion, IOP8 plays a role in human periodontitis. Targeted inhibition of IOP8 expression could effectively alleviate periodontal inflammation.