Treponema denticola Induces Epithelial Barrier Dysfunction in Polarized Epithelial Cells

Treponema Denticola Activates NF-κB Pathway via Toll-like Receptor 2

Treponema denticola is frequently isolated together with Porphyromonas gingivalis from the lesions seen in cases of chronic periodontitis and is considered a major pathogen of this disease. It has several virulence factors, including a major surface protein (Msp) and a major surface protease, dentilisin. The effect of these virulence factors on the host immune response remains to be elucidated, however. Toll-like receptors (TLRs) in the host can recognize pathogen-associated molecular patterns. Bacteria stimulate TLRs and activate the pro-inflammatory nuclear factor-kappa B pathway. Therefore, the aim of this study was to investigate the effect of T. denticola on TLR pathways. Toll-like receptor 4 and TLR2 reporter cell lines, which secrete alkaline phosphatase in response to TLR signals, were infected with the T. denticola wild type, an Msp-deficient mutant, a dentilisin-deficient mutant, or their extracts obtained via sonication. Signals from TLR2 or TLR4 cells were evaluated by alkaline phosphatase activity. Toll-like receptor 2 signals were detected in all T. denticola strains and sonication extracts, while no TLR4 signal was detected. Infection with the dentilisin-deficient mutant induced the strongest TLR2 signal among the strains. Sonication extracts of the wild type and Msp-deficient mutant showed the same level of TLR2 signaling. The TLR2 signal in the sonication extracts from the wild type was inhibited by Sparstolonin B, an antagonist of TLR2, in a dose-dependent manner. These results indicate that T. denticola is recognized by epithelial cells mainly via TLR2. The outer sheath structure may conceal potential ligands for TLR2.

Oral microbiota in the oral-genitourinary axis: identifying periodontitis as a potential risk of genitourinary cancers

Periodontitis has been proposed as a novel risk factor of genitourinary cancers: although periodontitis and genitourinary cancers are two totally distinct types of disorders, epidemiological and clinical studies, have established associations between them. Dysbiosis of oral microbiota has already been established as a major factor contributing to periodontitis. Recent emerging epidemiological evidence and the detection of oral microbiota in genitourinary organs indicate the presence of an oral-genitourinary axis and oral microbiota may be involved in the pathogenesis of genitourinary cancers. Therefore, oral microbiota provides the bridge between periodontitis and genitourinary cancers. We have carried out this narrative review which summarizes epidemiological studies exploring the association between periodontitis and genitourinary cancers. We have also highlighted the current evidence demonstrating the capacity of oral microbiota to regulate almost all hallmarks of cancer, and proposed the potential mechanisms of oral microbiota in the development of genitourinary cancers.

Paradigm shift in the pathogenesis and treatment of oral cancer and other cancers focused on the oralome and antimicrobial-based therapeutics

The oral microbiome is a community of microorganisms, comprised of bacteria, fungi, viruses, archaea, and protozoa, that form a complex ecosystem within the oral cavity. Although minor perturbations in the environment are frequent and compensable, major shifts in the oral microbiome can promote an unbalanced state, known as dysbiosis. Dysbiosis can promote oral diseases, including periodontitis. In addition, oral dysbiosis has been associated with other systemic diseases, including cancer. The objective of this review is to evaluate the epidemiologic evidence linking periodontitis to oral, gastrointestinal, lung, breast, prostate, and uterine cancers, as well as describe new evidence and insights into the role of oral dysbiosis in the etiology and pathogenesis of the cancer types discussed. Finally, we discuss how antimicrobials, antimicrobial peptides, and probiotics may be promising tools to prevent and treat these cancers, targeting both the microbes and associated carcinogenesis processes. These findings represent a novel paradigm in the pathogenesis and treatment of cancer focused on the oral microbiome and antimicrobial‐based therapies.

Microbial and Host Factors That Affect Bacterial Invasion of the Gingiva

Periodontitis is a chronic inflammation of the periodontium caused by the loss of homeostasis between subgingival biofilms and susceptible hosts. Bacterial invasion into the gingival tissue and persistent infection are major events that lead to chronic inflammation. The intratissue bacterial communities are as complex as the subgingival biofilms and can also form biofilm-like structures, which will serve as a reservoir for local and systemic infections. The epithelium forms physical, chemical, and immunological barriers against invading microbes. Nevertheless, many bacterial species can invade the gingival epithelium through transcellular and paracellular pathways. In addition, both genetic and environmental factors of the hosts can affect epithelial barrier functions and thus bacterial invasion of the gingiva. In this review, current evidence for the bacterial invasion of the gingival tissue in periodontitis has been summarized, and the microbial and host factors that determine bacterial invasion of the gingiva have been reviewed.