Background and Objective Although previous studies revealed the potential use of probiotics in the control of periodontitis, little is known about their interactions with gingival epithelial cells (GECs). Since GECs comprise the first defense in the subgingival microenvironment, the aim of this study was to evaluate the effect of probiotic lactobacilli and bifidobacteria strains on OBA‐9 cells challenged with Porphyromonas gingivalis. Methods Immortalized human GECs (OBA‐9) were challenged with live P. gingivalis (strains W83 and ATCC33277) and co‐infected with one of 12 tested probiotic strains at a multiplicity of infection (MOI) of 1:1000 for 2 hours. Bacterial adhesion and invasion were determined by antibiotic exclusion analysis and CFU counting. OBA‐9 viability was assessed by MTT assay, and levels of inflammatory mediators (TNF‐α, IL‐1β, and CXCL8) in the supernatants were determined by ELISA. The expression of genes encoding Toll‐like receptors (TLR2, TLR4) was evaluated by RT‐qPCR. Results Both strains of P. gingivalis were able to adhere and invade OBA‐9 cells, with significant loss in cell viability, increase in the levels of TNF‐α and IL‐1β, and upregulation of TLR4. However, co‐infection with probiotics attenuated these effects in P. gingivalis challenged GECs. Most probiotics maintained OBA‐9 viability and reduced pathogens adhesion and invasion. Furthermore, probiotics were able to adhere to GECs, which was enhanced for most strains in the presence of P. gingivalis. The synthesis of IL‐1β and TNF‐α by P. gingivalis in challenged GECs was reduced in co‐culture with most of the tested probiotics, whereas the secretion of CXCL8 increased, and TLR4 was downregulated. Conclusion Probiotics can alter the interaction of GECs with P. gingivalis by modulating the pathogen's ability to adhere and invade these cells, as well as by regulating the innate immune response. Such properties are strain‐specific and may indicate the most efficient probiotics to control periodontitis.

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Maresin-1 (MaR1) and Resolvin E1 (RvE1) are specialized pro-resolving lipid mediators (SPMs) that regulate inflammatory processes. We have previously demonstrated the hard and soft tissue regenerative capacity of RvE1 in an in vivo model of the periodontal disease characterized by inflammatory tissue destruction. Regeneration of periodontal tissues requires a well-orchestrated process mediated by periodontal ligament stem cells. However, limited data are available on how SPMs can regulate the regenerative properties of human periodontal ligament stem cells (hPDLSCs) under inflammatory conditions. Thus, we measured the impact of MaR1 and RvE1 in an in vitro model of hPDLSC under stimulation with IL-1β and TNF-α by evaluating pluripotency, migration, viability/cell death, periodontal ligament markers (α-smooth muscle actin, tenomodulin, and periostin), cementogenic-osteogenic differentiation, and phosphoproteomic perturbations. The data showed that the pro-inflammatory milieu suppresses pluripotency, viability, and migration of hPDLSCs; MaR1 and RvE1 both restored regenerative capacity by increasing hPDLSC viability, accelerating wound healing/migration, and up-regulating periodontal ligament markers and cementogenicosteogenic differentiation. Protein phosphorylation perturbations were associated with the SPM-induced regenerative capacity of hPDLSCs. Together, these results demonstrate that MaR1 and RvE1 restore or improve the regenerative properties of highly specialized stem cells when inflammation is present and offer opportunities for direct pharmacologic treatment of lost tissue integrity.

Inflammatory periodontal disease known as periodontitis is one of the most common conditions that affect human teeth and often leads to tooth loss. Due to the complexity of the periodontium, which is composed of several tissues, its regeneration and subsequent return to a homeostatic state is challenging with the therapies currently available. Cellular therapy is increasingly becoming an alternative in regenerative medicine/dentistry, especially therapies using mesenchymal stem cells, as they can be isolated from a myriad of tissues. Periodontal ligament stem cells (PDLSCs) are probably the most adequate to be used as a cell source with the aim of regenerating the periodontium. Biological insights have also highlighted PDLSCs as promising immunomodulator agents. In this review, we explore the state of knowledge regarding the properties of PDLSCs, as well as their therapeutic potential, describing current and future clinical applications based on tissue engineering techniques.

Periodontitis is an oral chronic inflammatory disease which has been associated with a wide range of systemic disorders some of which include diabetes, inflammatory bowel diseases, cardiovascular diseases, cancer, neurodegeneration, rheumatoid arthritis, and chronic liver diseases. [1][2][3][4][5][6][7] Periodontitis and these systemic conditions all share some degree of similarity in their pathophysiology which is characterized by a long-lasting deregulated inflammatory response.Today it is recognized that genetic predisposition, exposure to acquired risk factors and epigenetic changes throughout life play a decisive role for the development of immune-based disorders by modifying the host's susceptibility. 8,9 Given that time is required for their onset, the inflammatory imbalance resulting from one disease could directly alter the pathophysiology of the other or they could simply occur in a host sharing a similarly disturbed immunological background favorable for the development of general chronic disorders. Regardless of the perspective to be taken into account, periodontitis has an important place, whether as a warning time marker for the predisposition of other chronic diseases, or as an independent factor for their development or clinical worsening with direct effects on patients' uality of life, treatment outcome, and prognosis.The increasing knowledge also suggests that imbalances in the microbiota-immunity interactions may contribute to the onset of a multitude of immune-mediated diseases. 10 While how and when this dysbiosis develops in different organs is still unknown, oral bacteria such as Porphyromonas gingivalis and Fusobacterium nucleatum have been associated with various disorders distant from the oral cavity. [11][12][13] In this context, interactions between oral and gut microbiomes are complex, dynamic, and context-dependent since both sites are part of the multivariate environment of the gastrointestinal tract. Under physiological conditions they can keep a fine-tuned balance across the lifespan, but failures in this crosstalk due to a hostmicrobe disequilibrium have the potential to activate inflammatory networks in different organs. 14 The liver is among the organs that can be more affected by these biological networks and pathogenic disturbances since it maintains anatomical proximity and intense physiological interdependence with the intestine via metabolic exchange and translocation of bacteria. For this reason, interest in the so-called oral-gut-liver axis has emerged, along with the idea that the oral dysbiosis caused by unrestrained inflammation could affect the pathophysiology of chronic liver diseases via blood circulation or enteral route. 1,15,16,17 The activation of a susceptible host immune system by pathogenand damage-associated molecular patterns (PAMPs; DAMPs) in the periodontal milieu could induce the systemic overexpression of an array of pro-inflammatory cytokines and chemokines hence potentially impacting the hepatic metabolism. 11 In parallel, oral bacteria in the contex...