title: Regulation of IL-8 by Irsogladine maleate is involved in abolishment of Actinobacillus actinomycetemcomitans-induced reduction of gap-junctional intercellular communication.
abstract: Our previous report has shown that Irsogladine maleate (IM) counters and obviates the reduction in gap junction intercellular communication (GJIC) and the increase in IL-8 levels, respectively, induced by outer membrane protein 29 from Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) in cultured human gingival epithelial cells (HGEC). In addition, IM suppresses the increase in the secretion of IL-8 caused by whole live A. actinomycetemcomitans. These findings implicate the modulation of IL-8 levels by IM in abolishment of the reduction of GJIC in HGEC. Tight junctions are also responsible for cell-cell communication. Zonula occludens protein-1 (ZO-1) is a major tight junction protein. To investigate the regulatory mechanism of intercellular communication mediated by IM, in the present study, we focused on the involvement of IL-8 in A. actinomycetemcomitans-induced change in GJIC and ZO-1 expression in HGEC. IM countered the A. actinomycetemcomitans-induced reduction in levels of Connexin (CX) 43, suggesting that it could abolish the A. actinomycetemcomitans-induced reduction in GJIC in HGEC. CXCR-1 is a receptor of IL-8. The simultaneous addition of A. actinomycetemcomitans and anti-CXCR-1 antibody also abrogated the repression of GJIC and CX43 expression by A. actinomycetemcomitans in HGEC, although the anti-CXCR-1 antibody was less effective than IM. IM inhibited the IL-8-induced reduction in CX43 levels and GJIC in HGEC. IM countered the A. actinomycetemcomitans-induced reduction in the expression of ZO-1, although anti-CXCR-1 antibody did not influence the decrease in ZO-1 mRNA levels caused by A. actinomycetemcomitans. Furthermore, IL-8 had little effect on the mRNA levels of ZO-1. These findings suggest that IL-8 mediates the A. actinomycetemcomitans-induced reduction of GJIC and CX43 expression in HGEC. The regulation of IL-8 levels by IM in HGEC is partially involved in abrogation of the reduction of GJIC and CX43 expression by A. actinomycetemcomitans. Furthermore, the regulatory effect of IM on the expression of CX43 and ZO-1 is different.
authors.affiliation: Department of Periodontal Medicine, Division of Frontier Medical Science, Hiroshima University Graduate School of Biomedical Science, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan. tfuji@hiroshima-u.ac.jp
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fujita
authors.forename: Arata
authors.initials: A
authors.lastname: Ashikaga
authors.forename: Hideki
authors.initials: H
authors.lastname: Shiba
authors.forename: Yuushi
authors.initials: Y
authors.lastname: Uchida
authors.forename: Chikara
authors.initials: C
authors.lastname: Hirono
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Iwata
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Takeda
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Kishimoto
authors.forename: Reika
authors.initials: R
authors.lastname: Hirata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Shiba
authors.forename: Hidemi
authors.initials: H
authors.lastname: Kurihara
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects* / Q000502:physiology*; D002450:Cell Communication / Q000187:drug effects*; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D017629:Gap Junctions / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D014227:Triazines / Q000494:pharmacology*
chemical_list: D018031:Connexin 43; D016209:Interleukin-8; D014227:Triazines; C041836:irsogladine