12-OAHSA is a component of olive oil and mitigates obesity-induced inflammation.

Fatty acid esters of hydroxyl fatty acids (FAHFAs) are a new family of endogenous lipids that exert anti-inflammatory action. Among the various FAHFA isomers, the dietary source of oleic acid-hydroxy stearic acid (OAHSA) and its anti-inflammatory functions are poorly understood. This study investigated the composition of OAHSA isomers in dietary oils and the impact of 12-OAHSA on obesity-induced inflammation. Liquid chromatography with tandem mass spectrometry analysis revealed that various dietary oils, including fish oil, corn oil, palm oil, soybean oil, and olive oil, present a wide variation in OAHSA profiles and amounts. The highest amounts of total OAHSAs are present in olive oil including 12-OAHSA. Compared to vehicle-treated obese mice, administration of 12-OAHSA significantly improved glucose homeostasis, independent of body weight. 12-OAHSA-treated mice displayed significantly reduced accumulation of CD11c+ adipose tissue macrophages, and CD4+/CD8+ adipose tissue T lymphocytes. Concomitantly, the expression of pro-inflammatory cytokine genes and the nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway were significantly decreased in the 12-OAHSA-treated adipose tissue, while the expression of the anti-inflammatory gene Il10 was markedly increased. Moreover, in vitro cell culture experiments showed that 12-OAHSA significantly inhibited the lipopolysaccharides-induced inflammatory response in macrophages by suppressing the nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway. Collectively, these results indicated that 12-OAHSA, as a component of olive oil, mitigates obesity-induced insulin resistance by regulating AT inflammation. Therefore, 12-OAHSA could be used as a novel nutritional intervention against obesity-associated metabolic dysregulation.

Catechin ameliorates Porphyromonas gingivalis-induced inflammation via the regulation of TLR2/4 and inflammasome signaling.

BACKGROUND: Porphyromonas gingivalis is a major periodontopathogen found in patients with chronic periodontitis that can lead to alveolar bone or tooth loss. Interleukin-1ß (IL-1ß), a proinflammatory cytokine, is most relevant to the pathogenesis of periodontitis. Catechin is one of the main polyphenol compounds found in green tea and possesses a range of health benefits. This study examined the anti-inflammatory effects of catechin in THP-1-derived macrophages infected with P. gingivalis as well as its effects on P. gingivalis-induced periodontitis in a mouse model. METHODS: The cytokine levels and relevant protein expression in THP-1 cells were measured using an enzyme-linked immunosorbent assay and Western blot analysis, respectively. An apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) pyroptosome formation was measured by confocal laser scanning microscopy. Micro-computed tomography was used to determine the level of bone loss induced by a P. gingivalis oral infection. RESULTS: Catechin attenuated the production of IL-1ß by inhibiting pro-IL-1ß expression via the downregulation of nuclear factor-κB, p38 mitogen-activated protein kinase, and Toll-like receptor signaling. In addition, catechin inhibited the activation of inflammasomes induced by P. gingivalis, but did not affect the growth of P. gingivalis. Catechin reduced the level of alveolar bone loss in a P. gingivalis-induced periodontitis mouse model. CONCLUSION: Catechin possesses anti-inflammatory properties by reducing the level of IL-1ß production, suggesting that it can potentially be used for the prevention and treatment of periodontal inflammation caused by P. gingivalis.

Trans-cinnamic aldehyde inhibits Aggregatibacter actinomycetemcomitans-induced inflammation in THP-1-derived macrophages via autophagy activation.

BACKGROUND: Inflammation is an essential response against bacterial infection as a host defense mechanism, which can lead to tissue damage. Aggregatibacter actinomycetemcomitans (Aa) is major pathogen for aggressive periodontitis characterized by rapid destruction of periodontal tissue surrounding teeth. Trans-cinnamic aldehyde is a key bioactive compound of the cinnamon extracts, which has anti-inflammatory, antioxidant, antipyretic, antimicrobial, and anti-cancer properties. The objective of the present study was to investigate the anti-inflammatory effect of trans-cinnamic aldehyde against Aa infection in human THP-1 derived macrophages and on Aa-induced periodontitis in mice. METHODS: THP-1 cells were differentiated with phorbol 12-mystristate 13-acetate and were infected with live Aa. Trans-cinnamic aldehyde was pretreated 30 minutes before the bacterial infection. Cytokine production was determined by enzyme-linked immunosorbent assay (ELISA) and protein expressions were detected by Western blot analysis. Autophagosome formation was detected by Cyto-ID. Viable cell count was carried out to determine bacterial adhesion, internalization, and intracellular survival. Experimental periodontitis was induced by inoculating Aa orally to mice, and microcomputed tomography was used to evaluate bone loss. RESULTS: Pretreatment of trans-cinnamic aldehyde significantly inhibited Aa-stimulated release of tumor necrosis factor-α and interleukin (IL)-1ß. Pretreatment of trans-cinnamic aldehyde inhibited Aa-induced expression of TLR signaling pathway as well as the phosphorylation of JNK, p38, and nuclear factor (NF)-κB. Also, trans-cinnamic aldehyde treatment downregulated the expression of pro-IL-1ß, caspase-1, and inflammasome components. Trans-cinnamic aldehyde treatment significantly decreased intracellular survival of Aa. Moreover, the autophagosome formation and the expressions of autophagy markers including Beclin-1, ATG5, and LC3 were increased. Finally, trans-cinnamic aldehyde significantly inhibited bone loss in Aa-induced mouse periodontitis. CONCLUSIONS: Trans-cinnamic aldehyde inhibited Aa-stimulated expression of inflammatory responses and inhibited intracellular bacterial survival via autophagy activation. These results suggest that trans-cinnamic aldehyde may serve as an anti-inflammatory agent for aggressive periodontitis.

Elevated MicroRNA-128 in Periodontitis Mitigates Tumor Necrosis Factor-α Response via p38 Signaling Pathway in Macrophages.

BACKGROUND: Periodontitis is a chronic inflammatory disease resulting from an inflammatory response to subgingival plaque bacteria, including Porphyromonas gingivalis. MicroRNA (miRNA) is a current focus in regulating the inflammatory processes. In this study, the inflammatory miRNA expression in gingival tissues of patients with periodontitis and of healthy individuals is compared, and its role in regulating the inflammatory response is examined. METHODS: Gingival tissues from patients with periodontitis and healthy individuals were collected for miRNA microarray. THP-1 and CA9-22 cells were challenged with P. gingivalis, and miRNA expression was determined by real-time polymerase chain reaction. Target genes for miRNA were predicted using TargetScanHuman database, and miRNA gene expressions were reviewed using public databases. For the functional study, THP-1 cells were transfected with a miRNA-128 mimic, and target gene expression was compared with THP-1 cells challenged with P. gingivalis. For the tolerance test, THP-1 cells transfected with miRNA-128 mimic were treated with phorbol 12-myristate 13-acetate (PMA) or paraformaldehyde (PFA)-fixed Escherichia coli. Tumor necrosis factor (TNF)-α production was determined by enzyme-linked immunosorbent assay, and mitogen-activated protein kinase (MAPK) protein phosphorylation was determined by Western blot. RESULTS: Gingival tissues from patients with periodontitis showed increased expression of miRNA-128, miRNA-34a, and miRNA-381 and decreased expression of miRNA-15b, miRNA-211, miRNA-372, and miRNA-656. THP-1 cells and CA9-22 cells challenged with P. gingivalis showed increased miRNA-128 expression. Among the predicted miRNA-128 target genes, several genes that are involved in MAPK signaling pathway showed similar gene expression pattern between P. gingivalis challenge and miRNA-128 mimic transfection. In THP-1 cells transfected with miRNA-128 mimic, TNF-α production was lower, and phosphorylation of p38 was inhibited when challenged with PMA or PFA-fixed E. coli. CONCLUSION: miRNA-128 may be involved in mitigating the inflammatory response induced by P. gingivalis in periodontitis.

Aloin Inhibits Interleukin (IL)-1ß-Stimulated IL-8 Production in KB Cells.

BACKGROUND: Interleukin (IL)-1ß, which is elevated in oral diseases including gingivitis, stimulates epithelial cells to produce IL-8 and perpetuate inflammatory responses. This study investigates stimulatory effects of salivary IL-1ß in IL-8 production and determines if aloin inhibits IL-1ß-stimulated IL-8 production in epithelial cells. METHODS: Saliva was collected from volunteers to determine IL-1ß and IL-8 levels. Samples from volunteers were divided into two groups: those with low and those with high IL-1ß levels. KB cells were stimulated with IL-1ß or saliva with or without IL-1 receptor agonist or specific mitogen-activated protein kinase (MAPK) inhibitors. IL-8 production was measured by enzyme-linked immunosorbent assay (ELISA). MAPK protein expression involved in IL-1ß-induced IL-8 secretion was detected by Western blot. KB cells were pretreated with aloin, and its effect on IL-1ß-induced IL-8 production was examined by ELISA and Western blot analysis. RESULTS: Saliva with high IL-1ß strongly stimulated IL-8 production in KB cells, and IL-1 receptor agonist significantly inhibited IL-8 production. Low IL-1ß-containing saliva did not increase IL-8 production. IL-1ß treatment of KB cells induced activation of MAPK signaling molecules as well as nuclear factor-kappa B. IL-1ß-induced IL-8 production was decreased by p38 and extracellular signal-regulated kinase (ERK) inhibitor treatment. Aloin pretreatment inhibited IL-1ß-induced IL-8 production in a dose-dependent manner and inhibited activation of the p38 and ERK signaling pathway. Finally, aloin pretreatment also inhibited saliva-induced IL-8 production. CONCLUSIONS: Results indicated that IL-1ß in saliva stimulates epithelial cells to produce IL-8 and that aloin effectively inhibits salivary IL-1ß-induced IL-8 production by mitigating the p38 and ERK pathway. Therefore, aloin may be a good candidate for modulating oral inflammatory diseases.

Aggregatibacter actinomycetemcomitans-Induced AIM2 Inflammasome Activation Is Suppressed by Xylitol in Differentiated THP-1 Macrophages.

BACKGROUND: Aggressive periodontitis is characterized by rapid destruction of periodontal tissue caused by Aggregatibacter actinomycetemcomitans. Interleukin (IL)-1ß is a proinflammatory cytokine, and its production is tightly regulated by inflammasome activation. Xylitol, an anticaries agent, is anti-inflammatory, but its effect on inflammasome activation has not been researched. This study investigates the effect of xylitol on inflammasome activation induced by A. actinomycetemcomitans. METHODS: The differentiated THP-1 macrophages were stimulated by A. actinomycetemcomitans with or without xylitol and the expressions of IL-1ß and inflammasome components were detected by real time PCR, ELISA, confocal microscopy and Immunoblot analysis. The effects of xylitol on the adhesion and invasion of A. actinomycetemcomitans to cells were measured by viable cell count. RESULTS: A. actinomycetemcomitans increased pro IL-1ß synthesis and IL-1ß secretion in a multiplicity of infection- and time-dependent manner. A. actinomycetemcomitans also stimulated caspase-1 activation. Among inflammasome components, apoptosis-associated speck-like protein containing a CARD (ASC) and absent in melanoma 2 (AIM2) proteins were upregulated by A. actinomycetemcomitans infection. When cells were pretreated with xylitol, proIL-1ß and IL-1ß production by A. actinomycetemcomitans infection was significantly decreased. Xylitol also inhibited ASC and AIM2 proteins and formation of ASC puncta. Furthermore, xylitol suppressed internalization of A. actinomycetemcomitans into differentiated THP-1 macrophages without affecting viability of A. actinomycetemcomitans within cells. CONCLUSIONS: A. actinomycetemcomitans induced IL-1ß production and AIM2 inflammasome activation. Xylitol inhibited these effects, possibly by suppressing internalization of A. actinomycetemcomitans into cells. Thus, this study proposes a mechanism for IL-1ß production via inflammasome activation and discusses a possible use for xylitol in periodontal inflammation caused by A. actinomycetemcomitans.

Activation of NLRP3 and AIM2 inflammasomes by Porphyromonas gingivalis infection.

Porphyromonas gingivalis, a major periodontopathogen, is involved in the pathogenesis of periodontitis. Interleukin-1ß (IL-1ß), a proinflammatory cytokine, regulates innate immune responses and is critical for the host defense against bacterial infection. However, excessive IL-1ß is linked to periodontal destruction. IL-1ß synthesis, maturation, and secretion are tightly regulated by Toll-like receptor (TLR) signaling and inflammasome activation. We found much higher levels of inflammasome components in the gingival tissues from patients with chronic periodontitis than in those from healthy controls. To investigate the molecular mechanisms by which P. gingivalis infection causes IL-1ß secretion, we examined the characteristics of P. gingivalis-induced signaling in differentiated THP-1 cells. We found that P. gingivalis induces IL-1ß secretion and inflammatory cell death via caspase-1 activation. We also found that P. gingivalis-induced IL-1ß secretion and pyroptic cell death required both NLRP3 and AIM2 inflammasome activation. The activation of the NLRP3 inflammasome was mediated by ATP release, the P2X7 receptor, and lysosomal damage. In addition, we found that the priming signal via TLR2 and TLR4 activation precedes P. gingivalis-induced IL-1ß release. Our study provides novel insight into the innate immune response against P. gingivalis infection which could potentially be used for the prevention and therapy of periodontitis.