Odontogenic infection of Porphyromonas gingivalis (P.g.), a major periodontal pathogen, exacerbates pathological progression of non-alcoholic steatohepatitis (NASH). In this study, we aimed to clarify the detailed mechanism in which P.g. induced hepatic stellate cells (HSCs; key effector cells in liver fibrosis) activation. In the liver of high fat diet-induced NASH mouse model with P.g. odontogenic infection, immunolocalization of P.g. was detected. The number of hepatic crown-like structure, which was macrophage aggregation and related to liver fibrosis, was drastically increased and fibrosis area was also increased through upregulating immunoexpression of Phosphorylated Smad2 (key signaling molecule of TGF-β1) and Galectin-3. P.g.-secreted trypsin-like enzyme [gingipain; an activator of protease-activated receptor 2 (PAR2)] stimulated HSC proliferation and differentiation through Smad and ERK signaling induced by TGF-β1 produced from HSCs with P.g.-infection. Further, Galectin-3 produced from HSCs with P.g. infection and P.g.-derived LPS/lipoprotein stimulation stabilized TGFβ-receptor II resulting in increasing sensitivity for TGF-β1, finally leading to HSC differentiation via activating Smad and ERK signaling. In addition to them, hepatocytes (main component cells of liver) contributed to HSC activation through TGF-β1 and Galectin-3 production in paracrine manner. Collectively, P.g.-odontogenic infection exacerbates fibrosis of NASH by HSC activation through TGF-β1 and Gal-3 production from HSCs and hepatocytes.

Dental pulp plays an important role in the health of teeth. The aging of teeth is strongly related to the senescence of dental pulp cells. A novel adipokine, visfatin, is closely associated with cellular senescence. However, little is known about the effect of visfatin on the senescence of human dental pulp cells (hDPCs). Here, it was found that in vivo visfatin levels in human dental pulp tissues increase with age and are upregulated in vitro in hDPCs during premature senescence activated by H₂O₂, suggesting a correlation between visfatin and senescence. In addition, visfatin knockdown by small interfering RNA led to the reduction in hDPC senescence; however, treatment with exogenous visfatin protein induced the senescence of hDPCs along with increased NADPH consumption, which was reversed by FK866, a chemical inhibitor of visfatin. Furthermore, visfatin-induced senescence was associated with both the induction of telomere damage and the upregulation of senescence-associated secretory phenotype (SASP) factors as well as NF-κB activation, which were all inhibited by FK866. Taken together, these results demonstrate, for the first time, that visfatin plays a pivotal role in hDPC senescence in association with telomere dysfunction and the induction of SASP factors.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammatory bone destruction in which tumor necrosis factor alpha (TNF-α) plays a key role. Bovine lactoferrin (bLF) is a multifunctional protein with anti-inflammatory and immunomodulatory properties. This study aimed to clarify the inhibitory effects of bLF on the pathological progression of RA. The mannan-induced arthritis model in SKG mice (genetic RA model) was used. Orally applied liposomal bLF (LbLF) markedly reduced ankle joint swelling and bone destruction. Histologically, pannus formation and osteoclastic bone destruction were prevented in the LbLF-treated animals. Moreover, orally administered LbLF improved the balance between Th17 cells and regulatory T cells isolated from the spleen of mannan-treated SKG mice. In an in vitro study, the anti-inflammatory effects of bLF on TNF-α-induced TNF-α production and downstream signaling pathways were analyzed in human synovial fibroblasts from RA patients (RASFs). bLF suppressed TNF-α production from RASFs by inhibiting the nuclear factor kappa B and mitogen-activated protein kinase pathways. The intracellular accumulation of bLF in RASFs increased in an applied bLF dose-dependent manner. Knockdown of the lipoprotein receptor-related protein-1 (LRP1) siRNA gene reduced bLF expression in RASFs, indicating that exogenously applied bLF was mainly internalized through LRP-1. Immunoprecipitated proteins with anti-TNF receptor-associated factor 2 (TRAF2; an adapter protein/ubiquitin ligase) included bLF, indicating that bLF binds directly to the TRAF2-TRADD-RIP complex. This indicates that LbLF may effectively prevent the pathological progression of RA by suppressing TNF-α production by binding to the TRAF2-TRADD-RIP complex from the RASFs in the pannus. Therefore, supplemental administration of LbLF may have a beneficial effect on preventive/therapeutic reagents for RA.

FK866 possesses various functional properties, such as anti-angiogenic, anti-cancer, and anti-inflammatory activities. We previously demonstrated that premature senescence of human dental pulp cells (hDPCs) was induced by hydrogen peroxide (H₂O₂). The present study aimed to investigate whether H₂O₂-induced premature senescence of hDPCs is affected by treatment with FK866. We found that FK866 markedly inhibited the senescent characteristics of hDPCs after exposure to H₂O₂, as revealed by an increase in the number of senescence-associated β-galactosidase (SA-β-gal)-positive hDPCs and the upregulation of the p21 and p53 proteins, which acts as molecular indicators of cellular senescence. Moreover, the stimulatory effects of H₂O₂ on cellular senescence are associated with oxidative stress induction, such as excessive ROS production and NADPH consumption, telomere DNA damage induction, and upregulation of senescence-associated secretory phenotype factors (IL-1β, IL-6, IL-8, COX-2, and TNF-α) as well as NF-κB activation, which were all blocked by FK866. Thus, FK866 might antagonize H₂O₂-induced premature senescence of hDPCs, acting as a potential therapeutic antioxidant by attenuating oxidative stress-induced pathologies in dental pulp, including inflammation and cellular senescence.

Lactoferrin (LF), an iron-binding glycoprotein, has been reported to have anticancer properties. However, the molecular mechanisms behind its anticancer effects on oral squamous cell carcinoma (OSCC) have not yet been elucidated. Therefore, we aimed to clarify the effects of LF on invasion of OSCC, and its underlying molecular mechanism. OSCC cell lines, HSC2 and HOC313, were treated with bovine LF (bLF). The effects of bLF on cell invasion were examined by a chamber migration assay, wound healing assay, and Boyden chamber method with a basement-membrane-analogue. Expression levels of MMP-1, MMP-3, and AP-1 were examined using RT-PCR, qRT-PCR, and western blotting. Roles of LRP1, a receptor of bLF, on cell invasion were analyzed using siLRP1 knockdown cells. Furthermore, to clarify the importance of LRP1 in invasion, the effects of bLF on tPA-induced invasion of OSCC cells were examined. The invasion assays showed that bLF suppressed invasion of the OSCC cells. Moreover, bLF down-regulated AP-1, and resulted in reductions of MMP-1 and MMP-3. With SiLRP1 knockdown, OSCC cells failed to induce their invasion, and bLF was not able to exert its effects on invasion. Furthermore, bLF remarkably inhibited tPA-induced cell invasion. These findings suggest the importance of LRP1 in bLF-suppressed invasion of OSCC cells via the reduction of AP-1 and MMP production.