Intracellular bacterial pathogens have evolved highly specialized mechanisms to enter and survive intracellularly within their eukaryotic hosts. Rabs play an essential role in both
endocytic and exocytic traffic in eukaryotic cells . Rab5, one of the most studied Rab proteins in recent years, is involved in early steps of the endocytic process. Rab5 regulates intracellular membrane trafficking of several pathogens, including Salmonella enterica serovar Typhimurium [7–9], Mycobacterium spp , and Listeria monocytogenes . Rab5 may also mediate internalization of P. gingivalis in host cells; however, little is known about the role of Rab5 in P. gingivalis invasion. TNF-α is a potent pleiotropic proinflammatory cytokine and is released by a Ulixertinib nmr variety of different cell types in response to various Palbociclib purchase stimuli, including bacteria, parasites, viruses, cytokines and mitogens. TNF-α is involved in systemic and local inflammation due to stimulation of different signal transduction pathways, inducing the expression of a broad range of genes. TNF-α regulates a host response to infection; on the other hand, inappropriate expression of TNF-α has detrimental effects for the host. Deregulation of TNF-α has been implicated in the pathogenesis of numerous complex diseases, including periodontitis [12–14], cardiovascular diseases [15,16], diabetes mellitus [17,18], autoimmune diseases [19,20],
and cancer [21,22]. Clinical studies have shown an upregulation of TNF-α in periodontitis, e.g., in gingival crevicular fluid , in gingival tissues , and in plasma and serum [14,25]. TNF-α was shown to have an impact on different biological
processes, including induction of inflammatory mediators, such as matrix metalloproteases (MMPs), cytokines, chemokines and prostaglandins , endothelial cell activation and endothelial-leukocyte interactions , monocyte adhesion , mediating bone remodeling , and oxidative processes . P. gingivalis induces highest Anidulafungin (LY303366) Selleck YH25448 levels of TNF-α expression, followed by IL-1 and IL-6 . However, we have no information on whether TNF-α affects invasion of P. gingivalis in periodontal tissues. In the present study, we examined the effect of TNF-α on invasion of P. gingivalis in gingival epithelial cells and clarified the molecular mechanism by which TNF-α augments invasion of P. gingivalis. Results TNF-α augments invasion of P. gingivalis in gingival epithelial cells We first examined the effect of TNF-α on invasion of P. gingivalis in Ca9-22 cells. The cells were treated with 10 ng/ml of TNF-α for 3 h and were then incubated with P. gingivalis (MOI =100) for 1 h. Invasion of the cells by P. gingivalis was determined by an invasion assay. Invasion of Ca9-22 cells by P. gingivalis was observed without TNF-α pretreatment. However, the invasion was significantly increased by stimulation with TNF-α (Figure 1A). We also observed localization of intracellular P.