The therapeutic potential of regulatory T lymphocytes in periodontitis: A systematic review

TLR2 agonist prevents the progression of periapical lesions in mice by reducing osteoclast activity and regulating the frequency of Tregs

AIM

To evaluate the role of regulatory T lymphocytes (Tregs) in the presence or absence of the synthetic ligand Pam3Cys during the progression of periapical lesion in wild-type (WT) and toll-like receptor 2 knockout (TLR2KO) mice.

METHODOLOGY

A total of 130 C57BL/6 male WT and TLR2KO mice were allocated into control (n = 5) and experimental (periapical lesion induction) (n = 10) groups. In specific groups (WT+Pam3cys and TLR2KO+Pam3cys), the synthetic ligand Pam3cys was administered intraperitoneally every 7 days, according to the experimental period (14, 21 and 42 days). At the end of those periods, the animals were euthanized, and the mandible and the spleen were submitted to histotechnical processing. Mandible histological sections were analysed by haematoxylin and eosin, TRAP histoenzymology and immunohistochemistry (FOXP3, RANK, RANKL and OPG). Spleen sections were analysed by immunohistochemistry (FOXP3).

RESULTS

The inflammatory infiltrate and bone resorption were more intense in the TLR2KO group compared to the WT group. The animals that received the Pam3cys had smaller periapical lesions when compared to the animals that did not receive the ligand (p < .05). TLR2KO animals showed a significant increase in the number of osteoclasts when compared to TLR2KO+Pam3cys group (p < .05). At 21 days, the WT+Pam3cys group had a lower number of osteoclasts when compared to the WT animals (p = .02). FOXP3 expression was more intense in the WT+Pam3cys groups when compared to the WT animals in the 42 days (p = .03). In the spleen analysis, the WT+Pam3cys group also had a higher expression of FOXP3 when compared to the WT animals at 14 and 42 days (p = .02). Concerning RANKL, there was a reduction in staining in the KOTLR2+Pam3cys groups at 21 and 42 days (p = .03) and a higher binding ratio between RANK/RANKL in animals that did not receive the ligand.

CONCLUSION

Administration of the Pam3cys increased the proliferation of Tregs, showed by FOXP3 expression and prevented the progression of the periapical lesion in WT mice. On the other hand, in the TLR2KO animals, Treg expression was lower with larger areas of periapical lesions. Finally, systemic administration of the Pam3cys in KO animals was able to limit the deleterious effects of the absence of the TLR2 receptor.

Oral microbiota-host interaction: the chief culprit of alveolar bone resorption

There exists a bidirectional relationship between oral health and general well-being, with an imbalance in oral symbiotic flora posing a threat to overall human health. Disruptions in the commensal flora can lead to oral diseases, while systemic illnesses can also impact the oral cavity, resulting in the development of oral diseases and disorders. Porphyromonas gingivalis and Fusobacterium nucleatum, known as pathogenic bacteria associated with periodontitis, play a crucial role in linking periodontitis to accompanying systemic diseases. In periodontal tissues, these bacteria, along with their virulence factors, can excessively activate the host immune system through local diffusion, lymphatic circulation, and blood transmission. This immune response disruption contributes to an imbalance in osteoimmune mechanisms, alveolar bone resorption, and potential systemic inflammation. To restore local homeostasis, a deeper understanding of microbiota-host interactions and the immune network phenotype in local tissues is imperative. Defining the immune network phenotype in periodontal tissues offers a promising avenue for investigating the complex characteristics of oral plaque biofilms and exploring the potential relationship between periodontitis and associated systemic diseases. This review aims to provide an overview of the mechanisms underlying Porphyromonas gingivalis- and Fusobacterium nucleatum-induced alveolar bone resorption, as well as the immunophenotypes observed in host periodontal tissues during pathological conditions.

Comparing measurement properties of EQ-5D and SF-6D in East and South-East Asian populations: a scoping review

INTRODUCTION

Euro-Qol-5 Dimension (EQ-5D) and Short-Form 6-Dimension (SF-6D) are the most commonly used generic multi-attribute utility instruments (MAUI) to calculate quality-adjusted life-years (QALYs) in East and South-East Asia. This study aims to systematically review and summarize current evidence on comparing measurement properties of EQ-5D and SF-6D in East and South-East Asian populations.

AREAS COVERED

Guided by the PRISMA systematic review and meta-analysis guidelines, a systematic literature search was conducted in databases of PubMed, Web of Science, MEDLINE, EMBASE and CINAHL (until June 2022) to obtain studies which compared measurement properties (feasibility, reliability, validity, responsiveness, and sensitivity) and agreement of EQ-5D and SF-6D in the populations.

EXPERT OPINION

In general, both EQ-5D and SF-6D had good measurement properties in East and South-East Asian populations; but their utility scores cannot be used interchangeably. Compared to the 3-level EQ-5D, SF-6D had better sensitivity and lower ceiling effects, but the comparison results between the 5-level EQ-5D and SF-6D were inconsistent across populations. This scoping review found that most studies did not consider order effects, did not specify the versions of SF-6D, and ignored certain measurement properties (reliability, content validity, and responsiveness). These aspects need to be further explored in future studies.

Propolis anti-inflammatory effects on MAGE-1 and retinoic acid-treated dendritic cells and on Th1 and T regulatory cells

Background

Propolis exhibits huge potential in the pharmaceutical industry. In the present study, its effects were investigated on dendritic cells (DCs) stimulated with a tumor antigen (MAGE-1) and retinoic acid (RA) and on T lymphocytes to observe a possible differential activation of T lymphocytes, driving preferentially to Th1 or Treg cells.

Methods

Cell viability, lymphocyte proliferation, gene expression (T-bet and FoxP3), and cytokine production by DCs (TNF-α, IL-10, IL-6 and IL-1β) and lymphocytes (IFN-γ and TGF-β) were analyzed.

Results

MAGE-1 and RA alone or in combination with propolis inhibited TNF-α production and induced a higher lymphoproliferation compared to control, while MAGE-1 + propolis induced IL-6 production. Propolis in combination with RA induced FoxP3 expression. MAGE-1 induced IFN-γ production while propolis inhibited it, returning to basal levels. RA inhibited TGF-β production, what was counteracted by propolis.

Conclusion

Propolis affected immunological parameters inhibiting pro-inflammatory cytokines and favoring the regulatory profile, opening perspectives for the control of inflammatory conditions.

The Effect of GABAergic Cells Transplantation on Allodynia and Hyperalgesia in Neuropathic Animals: A Systematic Review With Meta-Analysis

The role of GABAergic cell transplantation in improving neuropathic pain is controversial. We comprehensively searched the relevant literature to identify animal studies of GABAergic cell transplantation that recorded pain behaviors as an outcome according to the Cochrane Handbook 5.0.2. Controlled studies assessing the administration of GABAergic neurons or GABAergic neuronal progenitor cells to rat or mouse neuropathic pain animal models were included. Basic design information and mechanical allodynia thresholds and heat hyperalgesia thresholds data were collected. The risk of bias for the animal experiments was assessed according to the SYRCLE's tool. This study included 10 full-text articles. GABAergic cells transplantation leads to a statistically significant improvement of allodynia (SMD = 5.26; 95% confidence interval: 3.02–7.51; P < 0.001) and hyperalgesia (SMD: 4.10; 95% confidence interval: 1.84–6.35; P < 0.001). Differentiated GABAergic cells and without antibiotics using may have a better effect for improving neuropathic pain. GABAergic cell transplantation is a promising treatment for improving neuropathic pain. This systematic review and meta-analysis evaluated the effects of GABAergic cell transplantation on neuropathic pain, which can guide future clinical trials and possible clinical treatments, and better attenuate neuropathic pain caused by abnormal circuit hyperexcitability.

Immunomodulatory strategies for bone regeneration: A review from the perspective of disease types

Tissue engineering strategies for treating bone loss to date have largely focused on targeting stem cells or vascularization. Immune cells, including macrophages and T cells, can also indirectly enhance bone healing via cytokine secretion to interact with other bone niche cells. Bone niche cues and local immune environment vary depending on anatomical location, size of defects and disease types. As such, it is critical to evaluate the role of the immune system in the context of specific bone niche and different disease types. This review focuses on immunomodulation research for bone applications using biomaterials and cell-based strategies, with a unique perspective from different disease types. We first reviewed applications for prolonging orthopaedic implant lifetime and enhancing fracture healing, two clinical challenges where immunomodulatory strategies were initially developed for orthopedic applications. We then reviewed recent research progress in harnessing immunomodulatory strategies for regenerating critical-sized, long bone or cranial bone defects, and treating osteolytic bone diseases. Remaining gaps in knowledge, future directions and opportunities were also discussed.

Immunotherapy with regulatory T and B cells in periodontitis

Periodontitis (PD), also known as gum disease, is a condition causing inflammatory bone resorption and tooth loss. Regulatory T cells (Tregs) and regulatory B cells (Bregs) are vital in controlling the immune response and hence play a role in infections and peripheral tolerance adjustment. These cells have immunosuppressive and tissue-repairing capabilities that are important for periodontal health; however, in inflammatory circumstances, Tregs may become unstable and dysfunctional, accelerating tissue deterioration. In recent years, Regulatory cell-mediated immunotherapy has been shown to be effective in many inflammatory diseases. Considering the roles of Tregs and Bregs in shaping immune responses, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the role of regulatory T and B cells, as well as their therapeutic applications in PD.

Methodological assessment of systematic reviews of in-vitro dental studies

BACKGROUND

Systematic reviews of in-vitro studies, like any other study, can be of heterogeneous quality. The present study aimed to evaluate the methodological quality of systematic reviews of in-vitro dental studies.

METHODS

We searched for systematic reviews of in-vitro dental studies in PubMed, Web of Science, and Scopus databases published up to January 2022. We assessed the methodological quality of the systematic reviews using a modified "A MeaSurement Tool to Assess systematic Reviews" (AMSTAR-2) instrument. The 16 items, in the form of questions, were answered with yes, no, or py (partial yes). Univariable and multivariable linear regression models were used to examine the association between systematic review characteristics and AMSTAR-2 percent score. Overall confidence in the results of the systematic reviews was rated, based on weaknesses identified in critical and non-critical AMSTAR-2 items.

RESULTS

The search retrieved 908 potential documents, and after following the eligibility criteria, 185 systematic reviews were included. The most researched topics were ceramics and dental bonding. The overall rating for the confidence in the results was critically low in 126 (68%) systematic reviews. There was high variability in the response among the AMSTAR-2 items (0% to 75% positively answered). The univariable analyses indicated dental specialty (p = 0.03), number of authors (coef: 1.87, 95% CI: 0.26, 3.47, p = 0.02), and year of publication (coef: 2.64, 95% CI: 1.90, 3.38, p < 0.01) were significantly associated with the AMSTAR-2 percent score. Whereas, in the multivariable analysis only specialty (p = 0.01) and year of publication (coef: 2.60, 95% CI: 1.84, 3.35, p < 0.001) remained significant. Among specialties, endodontics achieved the highest AMSTAR-2 percent score.

CONCLUSIONS

The methods of systematic reviews of in vitro dental studies were suboptimal. Year of publication and dental specialty were associated with AMSTAR-2 scores. The overall rating of the confidence in the results was low and critically low for most systematic reviews.

Carvone and its pharmacological activities: A systematic review

Natural products from plants have gained prominence in the search for therapeutic alternatives. Monoterpenes, such as carvone, are suggested as candidates for the treatment of several diseases. Therefore, the objective of this study is to review the pharmacological activities of carvone in experimental models in vitro and in vivo. For this, the searches were carried out in May 2020 (upgraded in July 2021) in the databases of PubMed, Web of Science and Scopus and gathered studies on the pharmacological activities of carvone. Two independent reviewers performed the selection of articles using the Rayyan application, extracted the relevant data and assessed the methodological quality of the selected studies using Syrcle's risk of bias tool. Ninety-one articles were selected that described 10 pharmacological activities of carvone, such as antimicrobial, antispasmodic, anti-inflammatory, antioxidant, antinociceptive, anticonvulsant, among others. The evaluation of the methodological quality presented an uncertain risk of bias for most studies. In light of that, carvone stands out as a viable and promising alternative in the treatment of several pathological conditions. However, carrying out studies to evaluate possible mechanisms of action and the safety of this monoterpene is recommended.

Polarization of human gingival fibroblasts by Th1-, Th2-, Th17-, and Treg-derived cytokines

BACKGROUND AND OBJECTIVE

The purpose of this study was to evaluate whether gingival fibroblasts (GFs) can be differently activated and polarized into distinct functional subtypes by T-helper (Th) cytokines.

METHODS

Gingival fibroblasts were stimulated with interferon (IFN)-γ, interleukin (IL)-4, IL-17, and transforming growth factor (TGF)-β, representative cytokines of Th1, Th2, Th17, and regulatory T cells, respectively, and the gene expression profiles were analyzed by microarray. Differentially expressed genes (DEGs) in GFs stimulated by 4 cytokines were screened, and a gene ontology (GO) analysis of the DEGs was conducted. To confirm the reliability of the microarray results, the DEGs that showed the largest differences compared with non-stimulated GFs were further analyzed by RT-PCR. To evaluate the effect of polarization on GFs responses to lipopolysaccharide (LPS), GFs stimulated by 4 cytokines were further stimulated with Escherichia coli LPS and mRNA levels of several genes were analyzed using RT-PCR.

RESULTS

Differentially expressed genes by 4 Th cytokines were enriched in different GO terms, and the patterns of gene expression on GFs were shown functionally different. GFs stimulated with IFN-γ (GF(IFN-γ)) up-regulated the expression of chemokines (chemokine (C-X-C motif) ligand (CXCL)9, -10, -11, chemokine (C-C motif) ligand (CCL)8), molecules involved in antigen presentation, complement component 3 (C3), and other immune response-related molecules, whereas they down-regulated the expression of several types of collagen, extracellular matrix (ECM) components, and DNA replication and nuclear protein-related molecules. By contrast, GF(IL-4) up-regulated the expression of ECM components, cell adhesion molecules, and tissue development-related molecules and down-regulated the expression of chemokines (CXCL10 and CXCL8) and adaptive immune response-related molecules. GF(IL-17) up-regulated the expression of chemokines and other molecules for neutrophil infiltration and activation, the pro-inflammatory cytokine IL-6, and C3. GF(TGF-β) up-regulated the expression of cell growth-related molecules, ECM components, several types of collagen, and cell adhesion molecules and down-regulated the expression of molecules related to complement activation and bacterial recognition. GFs stimulated by 4 cytokines responded differently to LPS.

CONCLUSION

These results show that Th cytokines can polarize GFs into cells with functionally distinct features: immune-activating but tissue-destructive GF(IFN-γ), tissue-reparative, and immune-inhibiting GF(IL-4), highly pro-inflammatory GF(IL-17), and potent tissue-reparative GF(TGF-β).

The Effects of Porphyromonas gingivalis on Atherosclerosis-Related Cells

Atherosclerosis (AS), one of the most common types of cardiovascular disease, has initially been attributed to the accumulation of fats and fibrous materials. However, more and more researchers regarded it as a chronic inflammatory disease nowadays. Infective disease, such as periodontitis, is related to the risk of atherosclerosis. Porphyromonas gingivalis (P. gingivalis), one of the most common bacteria in stomatology, is usually discovered in atherosclerotic plaque in patients. Furthermore, it was reported that P. gingivalis can promote the progression of atherosclerosis. Elucidating the underlying mechanisms of P. gingivalis in atherosclerosis attracted attention, which is thought to be crucial to the therapy of atherosclerosis. Nevertheless, the pathogenesis of atherosclerosis is much complicated, and many kinds of cells participate in it. By summarizing existing studies, we find that P. gingivalis can influence the function of many cells in atherosclerosis. It can induce the dysfunction of endothelium, promote the formation of foam cells as well as the proliferation and calcification of vascular smooth muscle cells, and lead to the imbalance of regulatory T cells (Tregs) and T helper (Th) cells, ultimately promoting the occurrence and development of atherosclerosis. This article summarizes the specific mechanism of atherosclerosis caused by P. gingivalis. It sorts out the interaction between P. gingivalis and AS-related cells, which provides a new perspective for us to prevent or slow down the occurrence and development of AS by inhibiting periodontal pathogens.

Humanized Mouse Models for the Study of Periodontitis: An Opportunity to Elucidate Unresolved Aspects of Its Immunopathogenesis and Analyze New Immunotherapeutic Strategies

Periodontitis is an oral inflammatory disease in which the polymicrobial synergy and dysbiosis of the subgingival microbiota trigger a deregulated host immune response, that leads to the breakdown of tooth-supporting tissues and finally tooth loss. Periodontitis is characterized by the increased pathogenic activity of T helper type 17 (Th17) lymphocytes and defective immunoregulation mediated by phenotypically unstable T regulatory (Treg), lymphocytes, incapable of resolving the bone-resorbing inflammatory milieu. In this context, the complexity of the immune response orchestrated against the microbial challenge during periodontitis has made the study of its pathogenesis and therapy difficult and limited. Indeed, the ethical limitations that accompany human studies can lead to an insufficient etiopathogenic understanding of the disease and consequently, biased treatment decision-making. Alternatively, animal models allow us to manage these difficulties and give us the opportunity to partially emulate the etiopathogenesis of periodontitis by inoculating periodontopathogenic bacteria or by placing bacteria-accumulating ligatures around the teeth; however, these models still have limited translational application in humans. Accordingly, humanized animal models are able to emulate human-like complex networks of immune responses by engrafting human cells or tissues into specific strains of immunodeficient mice. Their characteristics enable a viable time window for the study of the establishment of a specific human immune response pattern in an in vivo setting and could be exploited for a wider study of the etiopathogenesis and/or treatment of periodontitis. For instance, the antigen-specific response of human dendritic cells against the periodontopathogen Porphyromonas gingivalis favoring the Th17/Treg response has already been tested in humanized mice models. Hypothetically, the proper emulation of periodontal dysbiosis in a humanized animal could give insights into the subtle molecular characteristics of a human-like local and systemic immune response during periodontitis and support the design of novel immunotherapeutic strategies. Therefore, the aims of this review are: To elucidate how the microbiota-elicited immunopathogenesis of periodontitis can be potentially emulated in humanized mouse models, to highlight their advantages and limitations in comparison with the already available experimental periodontitis non-humanized animal models, and to discuss the potential translational application of using these models for periodontitis immunotherapeutics.

CD25+ B cells produced IL-35 and alleviated local inflammation during experimental periodontitis

BACKGROUND AND OBJECTIVE

Host immunity is crucial during periodontal inflammations. B cells are considered to have a function of immunoregulation, and TLRs are considered to be crucial in this process. The present study illustrates the potential roles and rules of CD25+ B cells during periodontitis, especially its effect on regulating host IL-35 level and Th1, Th17, and Treg differentiation.

MATERIAL AND METHODS

The proportion of local and systemic CD25+ B cell subpopulations from periodontitis models were identified by flow cytometry. To illustrate further mechanism, B cells were cultured with a different type of TLR activators. Expression of IL-10, IL-35, and TGF-β was detected by ELISA and real-time PCR. We also set adoptive transfer models by using CD25+ B cells. Alveolar bone erosion, proportion of Th1, Th17, and Tregs, and levels of IFN-γ, TNF-α, IL-1β, and IL-17 were identified.

RESULT

Periodontitis induces more CD25+ B cell subpopulations and promotes their IL-10, IL-35, and TGF-βproduction. TLR activators enhanced Breg proliferation and function. LPS+CpG obviously induced more CD25+ B cell differentiation and production of IL-10, IL-35, and TGF-β. Adoptive transfer of CD25+ B cells reduces alveolar bone destruction and local Tregs, proportion, especially the local level of IFN-γ and IL-17. In addition, adoptive transfer of CD25+ B cells remedies the pathological change in the proportion of IL-1β and Th1/Th17 in local lesions. We did not find any significant difference in peripheral blood, regardless of group and detected items.

CONCLUSION

Results of the present study clarify that CD25+ B cells enlarged and produced more IL-10, IL-35 and TGF-β during periodontitis, activation of TLR4 and TLR9 played crucial roles in this process. Also, CD25+ B cells alleviated periodontal inflammation and alveolar bone resorption. Our findings further expanded the potential of B cells during periodontitis.

Maintaining homeostatic control of periodontal bone tissue

Alveolar bone is a unique osseous tissue due to the proximity of dental plaque biofilms. Periodontal health and homeostasis are mediated by a balanced host immune response to these polymicrobial biofilms. Dysbiotic shifts within dental plaque biofilms can drive a proinflammatory immune response state in the periodontal epithelial and gingival connective tissues, which leads to paracrine signaling to subjacent bone cells. Sustained chronic periodontal inflammation disrupts "coupled" osteoclast-osteoblast actions, which ultimately result in alveolar bone destruction. This chapter will provide an overview of alveolar bone physiology and will highlight why the oral microbiota is a critical regulator of alveolar bone remodeling. The ecology of dental plaque biofilms will be discussed in the context that periodontitis is a polymicrobial disruption of host homeostasis. The pathogenesis of periodontal bone loss will be explained from both a historical and current perspective, providing the opportunity to revisit the role of fibrosis in alveolar bone destruction. Periodontal immune cell interactions with bone cells will be reviewed based on our current understanding of osteoimmunological mechanisms influencing alveolar bone remodeling. Lastly, probiotic and prebiotic interventions in the oral microbiota will be evaluated as potential noninvasive therapies to support alveolar bone homeostasis and prevent periodontal bone loss.

Association of bacterial vaginosis with periodontitis in a cross-sectional American nationwide survey

To explore the association between bacterial vaginosis (BV) and periodontitis (PD) and to determine whether PD and BV might be linked with systemic serum alterations. We used the National Health and Nutrition Examination Survey 2001-2004, with women aged 18-49 years old and diagnosed with or without BV according to Nugent's method. PD was defined according to the 2012 case definition. We compared serum counts according to the presence of PD and the presence of BV. Multivariable regression was used to explore and identify relevant variables towards the presence of BV. 961 women fulfilled the inclusion criteria. In women with BV, PD was associated with higher inflammation, characterized by increased white blood cells (p = 0.006) and lymphocyte (p = 0.009) counts. Predictive models presented a statistically significant association between PD and BV [Odds Ratio (OD) = 1.69, 95% Confidence Interval (CI): 1.09-2.61 for periodontitis; OD = 2.37, 95% CI: 1.30-4.29 for severe PD]. Fully adjusted models for age, smoking, body mass index, diabetes mellitus and number of systemic conditions reinforced this association [OD = 1.71, 95% CI: 1.06-2.76 for PD; OD = 2.21, 95% CI: 1.15-4.25 for severe PD]. An association between BV and PD is conceivable. PD was associated with higher systemic markers of inflammation in women with BV. Our data is novel and could serve as a foundation to guide future studies in the confirmation of this association and the underlying mechanisms.

Regulatory T cell phenotype and anti-osteoclastogenic function in experimental periodontitis

The alveolar bone resorption is a distinctive feature of periodontitis progression and determinant for tooth loss. Regulatory T lymphocytes (Tregs) display immuno-suppressive mechanisms and tissue repairing functions, which are critical to support periodontal health. Tregs may become unstable and dysfunctional under inflammatory conditions, which can even accelerate tissue destruction. In this study, experimental periodontitis was associated with the progressive and increased presence of Th17 and Treg-related mediators in the gingiva (IL-6, IL-17A, IL-17F, RANKL, IL-10, TGF-β and GITR; P < 0.05), and the proliferation of both Treg and Th17 cells in cervical lymph nodes. Tregs from cervical lymph nodes had reduced Foxp3 expression (> 25% MFI loss) and increased IL-17A expression (> 15%), compared with Tregs from spleen and healthy controls. Tregs gene expression analysis showed a differential signature between health and disease, with increased expression of Th17-associated factors in periodontitis-derived Tregs. The ex vivo suppression capacity of Tregs on osteoclastic differentiation was significantly lower in Tregs obtained from periodontally diseased animals compared to controls (P < 0.05), as identified by the increased number of TRAP⁺ osteoclasts (P < 0.01) in the Tregs/pre-osteoclast co-cultures. Taken together, these results demonstrate that Tregs become phenotypically unstable and lose anti-osteoclastogenic properties during experimental periodontitis; thus, further promoting the Th17-driven bone loss.

Tuning cytokines enriches dendritic cells and regulatory T cells in the periodontium

BACKGROUND

Periodontal disease results from the pathogenic interactions between the tissue, immune system, and microbiota; however, standard therapy fails to address the cellular mechanism underlying the chronic inflammation. Dendritic cells (DC) are key regulators of T cell fate, and biomaterials that recruit and program DC locally can direct T cell effector responses. We hypothesized that a biomaterial that recruited and programmed DC toward a tolerogenic phenotype could enrich regulatory T cells within periodontal tissue, with the eventual goal of attenuating T cell mediated pathology.

METHODS

The interaction of previously identified factors that could induce tolerance, granulocyte-macrophage colony stimulating factor (GM-CSF) and thymic stromal lymphopoietin (TSLP), with the periodontitis network was confirmed in silico. The effect of the cytokines on DC migration was explored in vitro using time-lapse imaging. Finally, regulatory T cell enrichment in the dermis and periodontal tissue in response to alginate hydrogels delivering TSLP and GM-CSF was examinedin vivo in mice using immunohistochemistry and live-animal imaging.

RESULTS

The GM-CSF and TSLP interactome connects to the periodontitis network. GM-CSF enhances DC migration in vitro. An intradermal injection of an alginate hydrogel releasing GM-CSF enhanced DC numbers and the addition of TSLP enriched FOXP3+ regulatory T cells locally. Injection of a hydrogel with GM-CSF and TSLP into the periodontal tissue in mice increased DC and FOXP3+ cell numbers in the tissue, FOXP3+ cells in the lymph node, and IL-10 in the tissue.

CONCLUSION

Local biomaterial-mediated delivery of GM-CSF and TSLP can enrich DC and FOXP3+ cells and holds promise for treating the pathologic inflammation of periodontal disease.

Periodontitis and circulating blood cell profiles: a systematic review and meta-analysis

Periodontitis is a chronic inflammatory disease with local and systemic implications. Evidence suggests consistent hematologic changes associated with periodontitis. Our aim was to critically appraise the available evidence on hemogram, leukogram, and thrombogram alterations in otherwise healthy patients suffering from periodontitis when compared with controls. For this systematic review (SR), we searched MEDLINE, Web of Science, EMBASE, and the Cochrane Library (CENTRAL) for studies published up to June 2020. Both observational and interventional studies with baseline standard hematologic levels were included. Outcomes of interest were baseline hemogram, leukogram, and thrombogram values and the impact of periodontitis treatment on these outcomes. Upon risk of bias assessment, data extraction and both qualitative and quantitative (standardized mean differences) analyses were performed. Random-effects meta-analyses were performed to provide pooled estimates. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed (PROSPERO Reg. No. CRD42020164531). A total of 45 studies, eight intervention and 37 case-control studies, were identified after the final search of 3,012 titles. Following quality assessment, 43 articles were deemed to have low risk of bias, and two articles moderate risk. Meta-analyses confirmed that periodontitis was associated with both white and red cell lineages. Severe chronic periodontitis was associated with greater white blood cell counts (mean difference [MD] = 0.53, 95% confidence interval [CI]: 0.26-0.79) when compared with controls. Periodontitis was associated with a larger number of neutrophils (MD = 7.16%, 95% CI: 5.96-8.37) and lower mean platelet volume (MD = 0.30 fL, 95% CI: 0.49 to -0.10) compared with healthy participants. Nonsurgical periodontal treatment was associated with a decrease in white blood cell (WBC) levels (MD = 0.28 10⁹/L, 95% CI: -0.47 to -0.08) in patients with chronic periodontitis. Periodontitis is associated with hematologic changes (Strength of Recommendation Taxonomy [SORT] A recommendation). Higher WBC levels, higher neutrophil levels, higher erythrocyte sedimentation rate, and lower mean platelet volumes are the most common blood count findings. The association between periodontitis and WBC could be causal in nature. Further assessment to determine whether periodontitis causes changes in circulating blood cells and to identify the molecular mechanisms underlying these associations is warranted.

Increase in serum and salivary neutrophil gelatinase-associated lipocalin levels with increased periodontal inflammation

OBJECTIVE

This study aimed to determine serum and salivary levels of neutrophil gelatinase-associated lipocalin (NGAL) and evaluate NGAL correlation with key anti-interleukin 10 (IL-10) and pro-inflammatory (IL-1β) cytokines in different severities of periodontal diseases. We also calculated the systemic inflammation using the periodontal inflamed surface area (PISA) to evaluate its correlation with NGAL in the study groups.

METHODOLOGY

Eighty systemically healthy and non-smoking individuals were separated into four groups of 20: clinically healthy (Group 1), gingivitis (Group 2), stage I generalized periodontitis (Group 3, Grade A), and stage III generalized periodontitis (Group 4, Grade A). Sociodemographic characteristics and periodontal parameters were recorded, and PISA was calculated. The serum and salivary levels of interleukin (IL)-1β, IL-10, and NGAL were determined using the enzyme-linked immunosorbent assay (ELISA).

RESULTS

We observed a significant increase in serum and salivary NGAL levels from healthy to periodontitis groups (p=0.000). Group 2 presented significantly higher serum and salivary IL-10 levels and salivary IL-1β levels than Group 3 (p=0.000). Serum and salivary parameters (IL-1β, IL-10, and NGAL levels) were strongly positively correlated to periodontal parameters and PISA values (p=0.000). Groups 2 and 3 showed overlapping PISA values.

CONCLUSION

The overlapping PISA values found in Groups 2 and 3 suggest that gingivitis might progress to a systemic inflammatory burden somewhat comparable to stage I periodontitis. This finding is supported by the higher serum and salivary cytokines/mediators levels in the gingivitis group than in stage I periodontitis group. Serum and salivary NGAL levels increased proportionally to disease severity and PISA. NGAL seems to play a role in the pathogenesis of periodontal disease, within the limitation of our study.

Boldine inhibits the alveolar bone resorption during ligature-induced periodontitis by modulating the Th17/Treg imbalance

BACKGROUND

During periodontitis, tooth-supporting alveolar bone is resorbed when there is an increased expression of the pro-osteolytic factor termed receptor activator of nuclear factor κB ligand (RANKL), which is responsible for osteoclast differentiation and activation. In periodontitis-affected tissues, the imbalance between T-helper type-17 (Th17) and T-regulatory (Treg) lymphocyte activity favors this RANKL overexpression. In this context, immunotherapeutic strategies aimed at modulating this Th17/Treg imbalance could eventually arrest the RANKL-mediated alveolar bone loss. Boldine has been reported to protect from pathological bone loss during rheumatoid arthritis and osteoporosis, whose pathogenesis is associated with a Th17/Treg imbalance. However, the effect of boldine on alveolar bone resorption during periodontitis has not been elucidated yet. This study aimed to determine whether boldine inhibits alveolar bone resorption by modulating the Th17/Treg imbalance during periodontitis.

METHODS

Mice with ligature-induced periodontitis were orally treated with boldine (10/20/40 mg/kg) for 15 consecutive days. Non-treated periodontitis-affected mice and non-ligated mice were used as controls. Alveolar bone loss was analyzed by micro-computed tomography and scanning electron microscopy. Osteoclasts were quantified by histological identification of tartrate-resistant acid phosphatase-positive cells. Production of RANKL and its competitive antagonist osteoprotegerin (OPG) were analyzed by ELISA, quantitative polymerase chain reaction (qPCR), and immunohistochemistry. The Th17 and Treg responses were analyzed by quantifying the T-cell frequency and number by flow cytometry. Also, the expression of their signature transcription factors and cytokines were quantified by qPCR.

RESULTS

Boldine inhibited the alveolar bone resorption. Consistently, boldine caused a decrease in the osteoclast number and RANKL/OPG ratio in periodontal lesions. Besides, boldine reduced the Th17-lymphocyte detection and response and increased the Treg-lymphocyte detection and response in periodontitis-affected tissues.

CONCLUSION

Boldine, administered orally, inhibited the alveolar bone resorption and modulated the Th17/Treg imbalance during experimental periodontitis.

Treg and TH17 link to immune response in individuals with peri-implantitis: a preliminary report

BACKGROUND AND OBJECTIVES

Treg and TH17 cells influence the inflammatory process in periodontal diseases and could also play in a similar pattern, an essential role in immune-inflammatory mechanisms involved in the destruction of the peri-implant tissues, peri-implantitis. Therefore, this study evaluated the levels of RORγT and FOXP3 gene expression in subjects with peri-implantitis and healthy peri-implant tissues.

METHODS

A total of 35 subjects with implant-supported restorations in both diseased and healthy clinical conditions (n = 15 healthy; n = 20 peri-implantitis) were included in this study. Peri-implantitis was defined as probing depth > 5 mm, bleeding on probing and/or suppuration, and peri-implant bone loss >4 mm. Peri-implant tissue biopsies were collected for analysis of the mRNA, RORγT, and FOXP3 expression levels. The samples were submitted to total RNA extraction, treatment with DNAse, and cDNA synthesis. Subsequently, real-time PCR reaction was performed to evaluate the levels of RORγT and FOXP3 gene expression to the reference gene. These were analyzed by the non-parametric Mann-Whitney method with a level of significance of 5%.

RESULTS

Higher gene expression levels of the transcription factors RORγT and FOXP3 were detected in the tissues affected by peri-implantitis when compared with healthy tissues (p < 0.05).

CONCLUSIONS

The present study demonstrated the possible existence of a hybrid TH17-Treg profile, based on the gene expression of transcription factors inducing differentiation of these cells. Further studies must be designed to gain a better understanding of the immunological mechanisms involved in the pathogenesis of peri-implantitis.

CLINICAL RELEVANCE

The levels of RORγT and FOXP3 transcription factors that were linked to cells with the FOXP3+RORγT+ phenotype could be used as a predictor of peri-implantitis progression.

Interleukin-35 inhibits alveolar bone resorption by modulating the Th17/Treg imbalance during periodontitis

AIM

T lymphocytes play a central role during the pathogenesis of periodontitis, and the imbalance between the pathogenic T-helper type 17 (Th17) and protective T-regulatory (Treg) lymphocytes determines the tooth-supporting alveolar bone resorption. Interleukin (IL)-35 is a novel anti-inflammatory cytokine with therapeutic properties in diseases whose pathogenesis is associated with the Th17/Treg imbalance; however, its role during periodontitis has not been established yet. This study aimed to elucidate whether IL-35 inhibits the alveolar bone resorption during periodontitis by modulating the Th17/Treg imbalance.

MATERIALS AND METHODS

Mice with ligature-induced periodontitis were treated with locally or systemically administrated IL-35. As controls, periodontitis-affected mice without IL-35 treatment and non-ligated mice were used. Alveolar bone resorption was measured by micro-computed tomography and scanning electron microscopy. The Th17/Treg pattern of the immune response was analysed by qPCR, ELISA, and flow cytometry.

RESULTS

IL-35 inhibited alveolar bone resorption in periodontitis mice. Besides, IL-35 induced less detection of Th17 lymphocytes and production of Th17-related cytokines, together with higher detection of Treg lymphocytes and production of Treg-related cytokines in periodontitis-affected tissues.

CONCLUSION

IL-35 is beneficial in the regulation of periodontitis; particularly, IL-35 inhibited alveolar bone resorption and this inhibition was closely associated with modulation of the periodontal Th17/Treg imbalance.

Involvement of Cathepsins in Innate and Adaptive Immune Responses in Periodontitis

Periodontitis is an infectious disease whereby the chronic inflammatory process of the periodontium stimulated by bacterial products induces specific host cell responses. The activation of the host cell immune system upregulates the production of inflammatory mediators, comprising cytokines and proteolytic enzymes, which contribute to inflammation and bone destruction. It has been well known that periodontitis is related to systemic inflammation which links to numerous systemic diseases, including diabetes and arteriosclerosis. Furthermore, periodontitis has been reported in association with neurodegenerative diseases such as Alzheimer's disease (AD) in the brain. Regarding immune responses and inflammation, cathepsin B (CatB) plays pivotal role for the induction of IL-1β, cathepsin K- (CatK-) dependent active toll-like receptor 9 (TLR9) signaling, and cathepsin S (CatS) which involves in regulating both TLR signaling and maturation of the MHC class II complex. Notably, both the production and proteolytic activities of cathepsins are upregulated in chronic inflammatory diseases, including periodontitis. In the present review, we focus on the roles of cathepsins in the innate and adaptive immune responses within periodontitis. We believe that understanding the roles of cathepsins in the immune responses in periodontitis would help to elucidate the therapeutic strategies of periodontitis, thus benefit for reduction of systemic diseases as well as neurodegenerative diseases in the global aging society.