Initial periodontal treatment affects nucleotide-binding domain leucine-rich repeat-containing protein 3 inflammasome priming in peripheral blood mononuclear cells

Objective: Accumulating evidence suggests an association between periodontitis and several systemic diseases, such as atherosclerosis. In the lesions of these diseases, nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC) and caspase-1 form inflammasome complex, which leads to the functional maturation of interleukin (IL)-1β via cleavage of caspase-1 in macrophages. IL-1β plays a critical role in the etiology of these diseases; however, inflammasome priming?specifically, IL-1β and NLRP3 upregulation?is necessary for effective IL-1β production. We investigated the effect of initial periodontal treatment on the inflammasome priming of peripheral blood mononuclear cells (PBMCs). Methods: Twenty-two patients with chronic periodontitis were enrolled in this study and given initial periodontal treatment. Peripheral blood samples were collected at baseline and re-evaluation (41.1 ± 29.1 d after the treatment), and the relative expression of IL-1β, and three inflammasome components, ASC, NLRP3 and Caspase-1, mRNA was determined using quantitative reverse transcription PCR. PBMCs were stimulated with silica crystals, and the IL-1β secretion was measured via enzyme-linked immunosorbent assay. Results: Probing pocket depth and bleeding on probing (BOP) were significantly improved after the treatment. Expression of IL-1β and ASC in the PBMCs decreased after the treatment. PBMCs stimulated with silica crystals secreted IL-1β. The treatment attenuated IL-1β secretion by PBMCs in low BOP percentages group whereas IL-1β secretion was increased in high BOP percentages group. Conclusion: Periodontal treatment altered the inflammasome priming status of the PBMCs, however, the effects on systemic diseases need to be further investigated

Dental Calculus Stimulates Interleukin-1beta Secretion by Activating NLRP3 Inflammasome in Human and Mouse Phagocytes

Dental calculus is a mineralized deposit associated with periodontitis. The bacterial components contained in dental calculus can be recognized by host immune sensors, such as Toll-like receptors (TLRs), and induce transcription of proinflammatory cytokines, such as IL-1beta. Studies have shown that cellular uptake of crystalline particles may trigger NLRP3 inflammasome activation, leading to the cleavage of the IL-1beta precursor to its mature form. Phagocytosis of dental calculus in the periodontal pocket may therefore lead to the secretion of IL-1beta, promoting inflammatory responses in periodontal tissues. However, the capacity of dental calculus to induce IL-1beta secretion in human phagocytes has not been explored. To study this, we stimulated human polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) with dental calculus collected from periodontitis patients, and measured IL-1beta secretion by ELISA. We found that calculus induced IL-1beta secretion in both human PMNs and PBMCs. Calculus also induced IL-1beta in macrophages from wild-type mice, but not in macrophages from NLRP3- and ASC-deficient mice, indicating the involvement of NLRP3 and ASC. IL-1beta induction was inhibited by polymyxin B, suggesting that LPS is one of the components of calculus that induces pro-IL-1beta transcription. To analyze the effect of the inorganic structure, we baked calculus at 250 degrees C for 1 h. This baked calculus failed to induce pro-IL-1beta transcription. However, it did induce IL-1beta secretion in lipid A-primed cells, indicating that the crystalline structure of calculus induces inflammasome activation. Furthermore, hydroxyapatite crystals, a component of dental calculus, induced IL-1beta in mouse macrophages, and baked calculus induced IL-1beta in lipid A-primed human PMNs and PBMCs. These results indicate that dental calculus stimulates IL-1beta secretion via NLRP3 inflammasome in human and mouse phagocytes, and that the crystalline structure has a partial role in the activation of NLRP3 inflammasome

The efficacy of a novel zinc-containing desensitizer CAREDYNE Shield for cervical dentin hypersensitivity: a pilot randomized controlled trial

Background: Recently, a novel zinc-containing desensitizer, CAREDYNE Shield, was developed. This new type of desensitizer induces chemical occlusion of dentinal tubules for desensitization and releases zinc ion for root caries prevention. Despite these features, its clinical effectiveness in the improvement of cervical dentine hypersensitivity remains to be elucidated. Thus, we aimed to evaluate the effectiveness of CAREDYNE Shield in patients with CDH.Methods: Forty CDH teeth which matched the eligibility criteria were randomly allocated to two groups in a 1:1 ratio: the CAREDYNE Shield group (intervention group) and the Nanoseal group (control group). The pain intensity in response to air stimuli, gingival condition, and oral hygiene status of CDH teeth were assessed before and at 4 weeks after treatment. The primary outcome was the reduction of pain intensity in response to air stimuli from baseline to 4 weeks after intervention.Results: From November 2019 to April 2021, 24 participants with 40 teeth were enrolled in this study and 33 teeth in 20 participants were assessed at 4 weeks after treatment. A significant reduction of pain in response to air stimuli was observed in both groups; however, no significant difference was observed between the groups.Conclusions: This study showed that CAREDYNE Shield is effective for CDH and its effectiveness is similar to Nanoseal

The Role of Cytokines Produced via the NLRP3 Inflammasome in Mouse Macrophages Stimulated with Dental Calculus in Osteoclastogenesis

Dental calculus (DC) is a common deposit in periodontitis patients. We have previously shown that DC contains both microbial components and calcium phosphate crystals that induce an osteoclastogenic cytokine IL-1β via the NLRP3 inflammasome in macrophages. In this study, we examined the effects of cytokines produced by mouse macrophages stimulated with DC on osteoclastogenesis. The culture supernatants from wild-type (WT) mouse macrophages stimulated with DC accelerated osteoclastogenesis in RANKL-primed mouse bone marrow macrophages (BMMs), but inhibited osteoclastogenesis in RANKL-primed RAW-D cells. WT, but not NLRP3-deficient, mouse macrophages stimulated with DC produced IL-1β and IL-18 in a dose-dependent manner, indicating the NLRP3 inflammasome-dependent production of IL-1β and IL-18. Both WT and NLRP3-deficient mouse macrophages stimulated with DC produced IL-10, indicating the NLRP3 inflammasome-independent production of IL-10. Recombinant IL-1β accelerated osteoclastogenesis in both RANKL-primed BMMs and RAW-D cells, whereas recombinant IL-18 and IL-10 inhibited osteoclastogenesis. These results indicate that DC induces osteoclastogenic IL-1β in an NLRP3 inflammasome-dependent manner and anti-osteogenic IL-18 and IL-10 dependently and independently of the NLRP3 inflammasome, respectively. DC may promote alveolar bone resorption via IL-1β induction in periodontitis patients, but suppress resorption via IL-18 and IL-10 induction in some circumstances

Initial periodontal treatment affects nucleotide-binding domain leucine-rich repeat-containing protein 3 inflammasome priming in peripheral blood mononuclear cells

Objective: Accumulating evidence suggests an association between periodontitis and several systemic diseases, such as atherosclerosis. In the lesions of these diseases, nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC) and caspase-1 form inflammasome complex, which leads to the functional maturation of interleukin (IL)-1β via cleavage of caspase-1 in macrophages. IL-1β plays a critical role in the etiology of these diseases; however, inflammasome priming—specifically, IL-1β and NLRP3 upregulation—is necessary for effective IL-1β production. We investigated the effect of initial periodontal treatment on the inflammasome priming of peripheral blood mononuclear cells (PBMCs). Methods: Twenty-two patients with chronic periodontitis were enrolled in this study and given initial periodontal treatment. Peripheral blood samples were collected at baseline and re-evaluation (41.1 ± 29.1 d after the treatment), and the relative expression of IL-1β, and three inflammasome components, ASC, NLRP3 and Caspase-1, mRNA was determined using quantitative reverse transcription PCR. PBMCs were stimulated with silica crystals, and the IL-1β secretion was measured via enzyme-linked immunosorbent assay. Results: Probing pocket depth and bleeding on probing (BOP) were significantly improved after the treatment. Expression of IL-1β and ASC in the PBMCs decreased after the treatment. PBMCs stimulated with silica crystals secreted IL-1β. The treatment attenuated IL-1β secretion by PBMCs in low BOP percentages group whereas IL-1β secretion was increased in high BOP percentages group. Conclusion: Periodontal treatment altered the inflammasome priming status of the PBMCs, however, the effects on systemic diseases need to be further investigated

Lipopolysaccharides from Periodontopathic Bacteria Porphyromonas gingivalis and Capnocytophaga ochracea Are Antagonists for Human Toll-Like Receptor 4

Toll-like receptors (TLRs) 2 and 4 have recently been identified as possible signal transducers for various bacterial ligands. To investigate the roles of TLRs in the recognition of periodontopathic bacteria by the innate immune system, a Chinese hamster ovary (CHO) nuclear factor-κB (NF-κB)-dependent reporter cell line, 7.7, which is defective in both TLR2- and TLR4-dependent signaling pathways was transfected with human CD14 and TLRs. When the transfectants were exposed to freeze-dried periodontopathic bacteria, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Capnocytophaga ochracea, and Fusobacterium nucleatum, and a non-oral bacterium, Escherichia coli, all species of the bacteria induced NF-κB-dependent CD25 expression in 7.7/huTLR2 cells. Although freeze-dried A. actinomycetemcomitans, F. nucleatum, and E. coli also induced CD25 expression in 7.7/huTLR4 cells, freeze-dried P. gingivalis did not. Similarly, lipopolysaccharides (LPS) extracted from A. actinomycetemcomitans, F. nucleatum, and E. coli induced CD25 expression in 7.7/huTLR4 cells, but LPS from P. gingivalis and C. ochracea did not. Furthermore, LPS from P. gingivalis and C. ochracea attenuated CD25 expression in 7.7/huTLR4 cells induced by repurified LPS from E. coli. LPS from P. gingivalis and C. ochracea also inhibited the secretion of interleukin-6 (IL-6) from U373 cells, the secretion of IL-1β from human peripheral blood mononuclear cells, and ICAM-1 expression in human gingival fibroblasts induced by repurified LPS from E. coli. These findings indicated that LPS from P. gingivalis and C. ochracea worked as antagonists for human TLR4. The antagonistic activity of LPS from these periodontopathic bacteria may be associated with the etiology of periodontal diseases

Cyclosporin A and phenytoin modulate inflammatory responses.

Gingival overgrowth is a common side-effect of administration of the immunosuppressant cyclosporin A and the anti-epileptic drug phenytoin. While cyclosporin-induced gingival overgrowth is often accompanied by gingival inflammation, phenytoin-induced gingival overgrowth usually forms fibrotic lesions. To determine whether these drugs alter the inflammatory responses of gingival fibroblasts, we investigated the effects of cyclosporin and phenytoin on Toll-like receptor (TLR)-mediated responses to microbial components. In Chinese hamster ovary reporter cell lines, cyclosporin alone triggered signaling, whereas phenytoin down-regulated signaling induced by the TLR2 or TLR4 ligand. In human gingival fibroblasts, cyclosporin alone did not induce evident inflammatory responses, but augmented the expression of CD54 and the production of interleukin (IL)-6 and IL-8 induced by TLR ligands, whereas phenytoin attenuated those responses. Cyclosporin also augmented CD54 expression in gingiva of mice injected with lipopolysaccharide. These results indicated that cyclosporin positively and phenytoin negatively modulated inflammatory responses of human gingival fibroblasts

T cell and periosteum cooperation in osteoclastogenesis induced by lipopolysaccharide injection in transplanted mouse tibia

Background/purpose: We previously reported that injedctions of lipopolysaccharide (LPS) into the gingiva of mice induce inflammatory bone resorption that actively involved T cells. Receptor activator of NF-κB ligand (RANKL), which is an essential factor for osteoclastogenesis, was reportedly produced by osteoblasts, fibroblasts, and T cells in vitro; however, it has not been established which cells affect osteoclastogenesis in vivo. Here we determined the roles of T cells and the periosteum on osteoclastogenesis in LPS-induced inflammatory bone resorption. Materials and methods: Thirty-five BALB/c (wild-type: WT) and 10 BALB/c-nu/nu (nude: Nu) mice congenitally lacking T cells were used. Using inbred WT mice, tibias were transplanted with and without the periostea [(+) and (−), respectively, n = 15 per group] into the dorsal subcutaneous connective tissue of WT or Nu mice. Each group received four injections around the transplanted site: experimental groups were injected with LPS, and control groups were injected with phosphate-buffered saline. Isolated tissues were prepared for histopathological observation of the transplanted bone surface. Results: Many infiltrating inflammatory cells were present near the surface of the tibias in the LPS-injected groups. Only the WT (+) LPS group showed osteoclasts. The number of mononuclear preosteoclasts and RANKL-positive cells was highest in the WT (+) LPS group, and there were no significant differences among the other three groups. Conclusion: T cells and the periosteum are closely involved in osteoclastogenesis in inflammatory bone resorption in vivo. Keywords: Osteoclastogenesis, Periosteum, Receptor activator of NF-κB ligand, T cell