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Effects of omentin-1 (intelectin-1) on the inflammatory reaction of oral keratinocytes upon stimulation with Porphyromonas gingivalis
Effects of omentin-1 (intelectin-1) on the inflammatory reaction of oral keratinocytes upon stimulation with Porphyromonas gingivalis
Background: Periodontal disease is complex and multifactorial in nature resulting in the progressive loss of tooth-supporting tissues. It arises from an imbalance between a dysbiotic plaque microbial community and the combating host defense mechanisms, leading to persistent and destructive local inflammation. Anti-inflammatory molecules may limit periodontal disease. Increasing evidence suggests that periodontitis is associated with obesity and related metabolic diseases. Omentin, an adipokine, has demonstrated anti-inflammatory properties. Omentin levels in gingival crevicular fluid (GCF) are decreased in periodontitis patients with obese or type 2 diabetes. Periodontal pathogens, in particular, Porphyromonas gingivalis (P. gingivalis), bear multiple virulence factors, which aid in evading host defenses and elicit inflammatory responses leading to periodontal destruction. A key virulence strategy is the targeting and invasion of host epithelial cells. The current study aimed to investigate how omentin modulates the inflammatory responses in human oral epithelial (BHY) cells elicited by exposure to P. gingivalis and its lipopolysaccharide (LPS). Methods: Oral epithelial BHY cells were used as an experimental model. Cells were infected with P. gingivalis/Escherichia coli (E. coli) or stimulated with their respective LPSs in independent experiments, followed by omentin treatment for durations up to 48 h. Increasing concentrations of omentin (50-200ng/ml) were used to treat LPS challenged cells. Real-time PCR and ELISA were used to quantify the effects of omentin on gene expression and pro- / anti-inflammatory mediator protein levels, and the levels of Toll-like receptors (TLR) 2 and 4. Results: P. gingivalis and E. coli infection each significantly up-regulated mRNA levels of pro-inflammatory cytokines; interleukin (IL) -1β, IL-6, tumor necrosis factor-α (TNF-α), and toll receptors (TLR)-2/4, while down-regulating anti-inflammatory fac-tors IL-13 and IL-25. Omentin significantly attenuated these stimulatory effects, attenuating bacterial infection-induced IL-1β, IL-6, TNF-α, and TLR-2/4 mRNA expression levels, while increasing IL-13 and IL-25. Similarly, significant but dose-dependent effects of omentin on counteracting LPS-induced increases in IL-1β, IL-6, TNF-α, and TLR-2/4 were noted, while it improved anti-inflammatory IL-10 levels. In a pleiotropic finding, omentin stimulated higher levels of pro-inflammatory cytokines under no microbial challenge. Conclusion: Our study demonstrated that omentin successfully attenuated pro-inflammatory cytokine production and TLR activation in bacteria/LPS challenged oral epithelial cells but was pro-inflammatory when applied to non-challenged cells. These findings support a premise that in presence of a microbial/LPS challenge, omen-tin aids epithelial barrier integrity, primarily performing an anti-inflammatory function that may counter local inflammation in periodontitis, similar to its role noted in other immune-inflammatory conditions.
Omentin, Porphyromonas gingivalis (P. gingivalis), Lipopolysaccharide (LPS), Oral keratinocytes, Inflammation, Periodontitis
Ning, Wanchen
2020
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Ning, Wanchen (2020): Effects of omentin-1 (intelectin-1) on the inflammatory reaction of oral keratinocytes upon stimulation with Porphyromonas gingivalis. Dissertation, LMU München: Faculty of Medicine
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Abstract

Background: Periodontal disease is complex and multifactorial in nature resulting in the progressive loss of tooth-supporting tissues. It arises from an imbalance between a dysbiotic plaque microbial community and the combating host defense mechanisms, leading to persistent and destructive local inflammation. Anti-inflammatory molecules may limit periodontal disease. Increasing evidence suggests that periodontitis is associated with obesity and related metabolic diseases. Omentin, an adipokine, has demonstrated anti-inflammatory properties. Omentin levels in gingival crevicular fluid (GCF) are decreased in periodontitis patients with obese or type 2 diabetes. Periodontal pathogens, in particular, Porphyromonas gingivalis (P. gingivalis), bear multiple virulence factors, which aid in evading host defenses and elicit inflammatory responses leading to periodontal destruction. A key virulence strategy is the targeting and invasion of host epithelial cells. The current study aimed to investigate how omentin modulates the inflammatory responses in human oral epithelial (BHY) cells elicited by exposure to P. gingivalis and its lipopolysaccharide (LPS). Methods: Oral epithelial BHY cells were used as an experimental model. Cells were infected with P. gingivalis/Escherichia coli (E. coli) or stimulated with their respective LPSs in independent experiments, followed by omentin treatment for durations up to 48 h. Increasing concentrations of omentin (50-200ng/ml) were used to treat LPS challenged cells. Real-time PCR and ELISA were used to quantify the effects of omentin on gene expression and pro- / anti-inflammatory mediator protein levels, and the levels of Toll-like receptors (TLR) 2 and 4. Results: P. gingivalis and E. coli infection each significantly up-regulated mRNA levels of pro-inflammatory cytokines; interleukin (IL) -1β, IL-6, tumor necrosis factor-α (TNF-α), and toll receptors (TLR)-2/4, while down-regulating anti-inflammatory fac-tors IL-13 and IL-25. Omentin significantly attenuated these stimulatory effects, attenuating bacterial infection-induced IL-1β, IL-6, TNF-α, and TLR-2/4 mRNA expression levels, while increasing IL-13 and IL-25. Similarly, significant but dose-dependent effects of omentin on counteracting LPS-induced increases in IL-1β, IL-6, TNF-α, and TLR-2/4 were noted, while it improved anti-inflammatory IL-10 levels. In a pleiotropic finding, omentin stimulated higher levels of pro-inflammatory cytokines under no microbial challenge. Conclusion: Our study demonstrated that omentin successfully attenuated pro-inflammatory cytokine production and TLR activation in bacteria/LPS challenged oral epithelial cells but was pro-inflammatory when applied to non-challenged cells. These findings support a premise that in presence of a microbial/LPS challenge, omen-tin aids epithelial barrier integrity, primarily performing an anti-inflammatory function that may counter local inflammation in periodontitis, similar to its role noted in other immune-inflammatory conditions.