Smad6 Methylation Represses NFκB Activation and Periodontal Inflammation

A nucleoside-based supramolecular hydrogel integrating localized self-delivery and immunomodulation for periodontitis treatment

Periodontitis is a highly prevalent oral disease characterized by bacterial-induced hyperactivation of the host immune system, leading to a sustained inflammatory response and osteoclastic activity, which ultimately results in periodontal destruction. In this work, an immunomodulatory supramolecular hydrogel for the topical treatment of periodontitis was synthesized using a simple one-pot method. This phenylboronate ester-based 8AGPB hydrogel exhibited excellent stability, self-healing properties, injectability, and biocompatibility. During degradation, the 8AGPB hydrogel releases immunomodulatory agent 8-aminoguanosine (8AG), which regulates MAPK and NF-κB signaling pathways by modulation of second messengers in macrophages. In combination with 1,4-phenylenediboronic acid (PBA), which possesses antioxidant properties, 8AG effectively inhibits ROS production and oxidative damage in LPS-stimulated macrophages, lowering the M1/M2 macrophage polarization ratio and reducing the secretion of pro-inflammatory factors. In an experimental periodontitis model using C57BL/6 mice, periodontal injection of the 8AGPB hydrogel reduced inflammatory infiltration and osteoclastic activity through immunomodulation and inhibition of osteoclast differentiation, thereby ameliorating periodontal destruction during periodontitis progression. Overall, the 8AGPB supramolecular hydrogel, serving as an injectable self-delivery platform for 8AG, may represent a promising novel strategy for periodontitis treatment and offer insights for the development of future topical anti-inflammatory systems.

Insight into the role of macrophages in periodontitis restoration and development

Periodontitis is one of the chronic diseases that have the greatest impact on human health, and it is associated with several other chronic diseases. Tissue damage associated with periodontitis is often connected with immune response. Immune cells are a crucial component of the human immune system and are directly involved in periodontitis during the inflammatory phase of the disease. Macrophages, as a key component of the immune system, are responsible for defence, antigen presentation and phagocytosis in healthy tissue. They are also closely linked to the development and resolution of periodontitis, through mechanisms such as macrophage polarization, pattern recognition receptors recognition, efferocytosis, and Specialized Pro-resolving Mediators (SPMs) production. Additionally, apoptosis and autophagy are also known to play a role in the recovery of periodontitis. This review aims to investigate the aforementioned mechanisms in more detail and identify novel therapeutic approaches for periodontitis.

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

MicroRNA-671-5p regulates the inflammatory response of periodontal ligament stem cells via the DUSP8/p38 MAPK pathway

BACKGROUND

MicroRNAs are differentially expressed in periodontitis tissues. They are involved in cellular responses to inflammation and can be used as markers for diagnosing periodontitis. Microarray analysis showed that the expression level of microRNA-671-5p in periodontal tissues of patients with periodontitis was increased. In this study, we investigated the mechanism of action of microRNA-671-5p in human periodontal ligament stem cells (hPDLSCs) under inflammatory conditions.

METHODS AND RESULTS

HPDLSCs were treated with lipopolysaccharide (LPS) to establish an inflammation model. The cell survival rate was determined using the cell counting kit-8 (CCK8). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses were used to detect the expression of microRNA-671-5p and dual-specificity phosphatase (DUSP) 8 proteins, respectively, Interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α were detected using qRT-PCR and Enzyme-linked immunosorbent assay (ELISA). A dual-luciferase reporter system was employed to determine the relationship between micoRNA-671-5p and DUSP8 expression. Activation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway was confirmed using western blot analysis. Following the treatment of hPDLSCs with LPS, the expression levels of microRNA-671-5p in hPDLSCs were increased, cell viability decreased, and the expression of inflammatory factors displayed an increasing trend. MicroRNA-671-5p targets and binds to DUSP8. Silencing microRNA-671-5p or overexpressing DUSP8 can improve cell survival rate and reduce inflammatory responses. When DUSP8 was overexpressed, the expression of p-p38 was reduced.

CONCLUSIONS

microRNA-671-5p targets DUSP8/p38 MAPK pathway to regulate LPS-induced proliferation and inflammation in hPDLSCs.

Protein arginine methyltransferase 1, a major regulator of biological processes

Protein arginine methyltransferase 1 (PRMT1) is a major type I arginine methyltransferase that catalyzes the formation of monomethyl and asymmetric dimethylarginine in protein substrates. It was first identified to asymmetrically methylate histone H4 at the third arginine residue forming the H4R3me2a active histone mark. However, several protein substrates are now identified as being methylated by PRMT1. As a result of its association with diverse classes of substrates, PRMT1 regulates several biological processes like chromatin dynamics, transcription, RNA processing, and signal transduction. The review provides an overview of PRMT1 structure, biochemical features, specificity, regulation, and role in cellular functions. We discuss the genomic distribution of PRMT1 and its association with tRNA genes. Further, we explore the different substrates of PRMT1 involved in splicing. In the end, we discuss the proteins that interact with PRMT1 and their downstream effects in diseased states.

The role of protein arginine N-methyltransferases in inflammation

Protein arginine methyltransferases (PRMTs) promote the methylation of numerous proteins at their arginine residues. An increasing number of publications have suggested that dysregulation of PRMTs participates in various human diseases, such as cardiovascular diseases, cancer, diabetes and neurodegenerative disorders. Inflammation is one normal response to infection or injury by immune system, which can keep body homeostasis. Emerging data reveal that inflammation is associated with the development of numerous diseases. Moreover, accumulated evidence proves that PRMTs have been characterized to regulate inflammation in various diseases. In this review article, we delineate the function and molecular mechanism of PRMTs in regulation of inflammation in current literature. Moreover, we discuss that targeting PRMTs by its inhibitors and compounds could have therapeutic potential.

Akkermansia muciniphila inhibited the periodontitis caused by Fusobacterium nucleatum

Periodontitis is the most important cause of tooth loss in adults and is closely related to various systemic diseases. Its etiologic factor is plaque biofilm, and the primary treatment modality is plaque control. Studies have confirmed that Fusobacterium nucleatum can cause periodontitis through its virulence factors and copolymerizing effects with other periodontal pathogens, such as the red complex. Inhibiting F. nucleatum is an essential target for preventing periodontitis. The time-consuming and costly traditional periodontal treatment, periodontal scaling, and root planing are a significant burden on individual and public health. Antibiotic use may lead to oral microbial resistance and microbiome imbalance, while probiotics regulate microbial balance. Akkermansia muciniphila is a critical probiotic isolated from the human intestine. It can protect the integrity of the epithelial barrier, regulate and maintain flora homeostasis, improve metabolism, and colonize the oral cavity. Its abundance is inversely correlated with various diseases. We hypothesized that A. muciniphila could inhibit the effects of F. nucleatum and alleviate periodontitis. Bacterial co-culture experiments showed that A. muciniphila could inhibit the expression of the virulence gene of F. nucleatum. After treating gingival epithelial cells (GECs) with F. nucleatum and A. muciniphila, transcriptome sequencing and ELISA experiments on medium supernatant showed that A. muciniphila inhibited the inflammatory effect of F. nucleatum on GECs by inhibiting TLR/MyD88/NF-κB pathway modulation and secretion of inflammatory factors. Finally, animal experiments demonstrated that A. muciniphila could inhibit F. nucleatum-induced periodontitis in BALB/c mice.

SENP3 deletion promotes M2 macrophage polarization and accelerates wound healing through smad6/IκB/p65 signaling pathway

Macrophages preferentially polarize to the anti-inflammatory M2 subtype in response to alterations in the wound microenvironment. SUMO-specific protease 3 (SENP3), a SUMO-specific protease, has been proven to regulate inflammation in macrophages by deSUMOylating substrate proteins, but its contribution to wound healing is poorly defined. Here, we report that SENP3 deletion promotes M2 macrophage polarization and accelerates wound healing in macrophage-specific SENP3 knockout mice. Notably, it affects wound healing through the suppression of inflammation and promotion of angiogenesis and collagen remodeling. Mechanistically, we identified that SENP3 knockout facilitates M2 polarization through the Smad6/IκB/p65 signaling pathway. SENP3 knockout elevated the expression of Smad6 and IκB. Moreover, Smad6 silencing enhanced the expression of p-p65 and proinflammatory cytokines while inhibiting the level of IκB. Our study revealed the essential role of SENP3 in M2 polarization and wound healing, which offers a theoretical basis for further research and a therapeutic strategy for wound healing.

Transcriptomic analysis of the innate immune response to in vitro transfection of plasmid DNA

The innate immune response to cytosolic DNA is intended to protect the host from viral infections, but it can also inhibit the delivery and expression of therapeutic transgenes in gene and cell therapies. The goal of this work was to use mRNA sequencing to identify genes that may influence transfection efficiency in four different cell types (PC-3, Jurkat, HEK-293T, and primary T cells). The highest transfection efficiency was observed in HEK-293T cells, which upregulated only 142 genes with no known antiviral functions after transfection with lipofectamine. Lipofection upregulated 1,057 cytokine-stimulated genes (CSGs) in PC-3 cells, which exhibited a significantly lower transfection efficiency. However, when PC-3 cells were transfected in serum-containing media or electroporated, the observed transfection efficiencies were significantly higher while the expression levels of cytokines and CSGs decreased. In contrast, lipofection of Jurkat and primary T cells only upregulated a few genes, but several of the antiviral CSGs that were absent in HEK-293T cells and upregulated in PC-3 cells were observed to be constitutively expressed in T cells, which may explain the relatively low Lipofection efficiencies observed with T cells (8%-21% GFP⁺). Indeed, overexpression of one CSG (IFI16) significantly decreased transfection efficiency in HEK-293T cells.

Emerging role of epigenetic regulations in periodontitis: a literature review

Periodontitis is mainly initiated by periodontal pathogens including Porphyromonas gingivalis, and bad living habits such as smoking aggravate its incidence and severity. The development of periodontitis is closely related to the host's immune responses and the secretion of various cytokine networks. Moreover, periodontitis has an important connection with the development of systemic diseases. Recently, epigenetics which is a fast-developing hot research area has provided new insights into the research of various diseases including periodontitis. Epigenetics is an important supplement to the regulation of gene expression. The study of epigenetics is about causing heritable gene expression or cell phenotype changes through certain mechanisms without changing the DNA sequence. It mainly includes histone modification, DNA methylation, non-coding RNA and the latest research hotspot m6A RNA methylation. In the review, we comprehensively summarize the latest literature on the potential epigenetic regulations in various aspects of periodontitis.

How Protein Methylation Regulates Steroid Receptor Function

Steroid receptors (SRs) are members of the nuclear hormonal receptor family, many of which are transcription factors regulated by ligand binding. SRs regulate various human physiological functions essential for maintenance of vital biological pathways, including development, reproduction, and metabolic homeostasis. In addition, aberrant expression of SRs or dysregulation of their signaling has been observed in a wide variety of pathologies. SR activity is tightly and finely controlled by post-translational modifications (PTMs) targeting the receptors and/or their coregulators. Whereas major attention has been focused on phosphorylation, growing evidence shows that methylation is also an important regulator of SRs. Interestingly, the protein methyltransferases depositing methyl marks are involved in many functions, from development to adult life. They have also been associated with pathologies such as inflammation, as well as cardiovascular and neuronal disorders, and cancer. This article provides an overview of SR methylation/demethylation events, along with their functional effects and biological consequences. An in-depth understanding of the landscape of these methylation events could provide new information on SR regulation in physiology, as well as promising perspectives for the development of new therapeutic strategies, illustrated by the specific inhibitors of protein methyltransferases that are currently available.

Alterations of Asymmetric Dimethylarginine (ADMA)-Containing Protein Profiles Associated with Chronic Pancreatitis Pathogenesis

Objective

The pathophysiological mechanisms of chronic pancreatitis (CP) still remain poorly understood. In this study, we aimed to characterize asymmetric dimethylarginine (ADMA)-containing proteins in pancreatic tissues and its relationship with CP pathogenesis.

Methods

Totally 36 patients with CP were enrolled in this study. Seven other cholangiocarcinoma patients without pancreas involvements or patients with benign pancreatic tumors were included as the control group. Total proteins in human pancreatic tissues were digested by trypsin, and ADMA-containing peptides were enriched via immunoaffinity purification. The LC-MS/MS was performed to characterize ADMA-containing peptides and their modification sites in CP tissues. Relative asymmetric arginine dimethylation levels of HNRNPA3 proteins in human pancreatic tissues were detected by the immunoprecipitation combined with Western blot. The serum inflammatory factors were determined via the ELISA method.

Results

A total of 134 ADMA sites in the control group and 137 ADMA sites in CP tissues were characterized by mass spectrometry, which belong to 93 and 94 ADMA-containing proteins in the control group and CP tissues, respectively. Glycine and proline residues were significantly overrepresented in the flanking sequences of ADMA sites. ADMA-containing proteins in the CP tissues were associated with various biological processes, especially the RNA metabolism and splicing pathways. Multiple protein members of the spliceosome pathway such as HNRNPA3 possess ADMA sites in the CP tissues. HNRNPA3 dimethylation levels were greatly increased in CP tissues, which were positively correlated with inflammatory factors.

Conclusion

The pathogenesis of CP is associated with alterations of asymmetric arginine dimethylation in pancreatic tissues.

Structure, Activity, and Function of PRMT1

PRMT1, the major protein arginine methyltransferase in mammals, catalyzes monomethylation and asymmetric dimethylation of arginine side chains in proteins. Initially described as a regulator of chromatin dynamics through the methylation of histone H4 at arginine 3 (H4R3), numerous non-histone substrates have since been identified. The variety of these substrates underlines the essential role played by PRMT1 in a large number of biological processes such as transcriptional regulation, signal transduction or DNA repair. This review will provide an overview of the structural, biochemical and cellular features of PRMT1. After a description of the genomic organization and protein structure of PRMT1, special consideration was given to the regulation of PRMT1 enzymatic activity. Finally, we discuss the involvement of PRMT1 in embryonic development, DNA damage repair, as well as its participation in the initiation and progression of several types of cancers.

Role of Inhibitor SMADs in Stage 3 Grade B periodontitis before and after periodontal treatment

OBJECTIVE

This study aimed to examine the levels of transforming growth factor-beta (TGF-β) and inhibitory-Smads (I-Smads) in saliva and gingival crevicular fluid (GCF) in patients with Stage 3 Grade B periodontitis before and after non-surgical periodontal treatment.

BACKGROUND

Recently, it has been stated that Smads play an active role in all conditions where TGF-β is involved, including periodontal inflammation.

METHODS

Twenty healthy participants (control) and 20 patients with Stage 3, Grade B periodontitis were recruited. GCF and saliva samples and clinical periodontal recordings were investigated at the baseline and 1 month after treatment. TGF-β and I-Smads (Smads 6 and 7) were determined by ELISA.

RESULTS

Salivary Smad6 and Smad7 levels were significantly lower in the periodontitis group than healthy controls (p < .05), while there was no difference in salivary TGF-β levels between groups at baseline (p > .05). The total amounts and concentrations of GCF TGF-β, Smad6, and Smad7 were significantly lower in the periodontitis group than healthy controls at baseline (p < .05), and then decreased in concentration levels with treatment (p < .001). Positive correlations were found between total amounts and concentrations of GCF TGF-β, Smad6, and Smad7 (p < .05).

CONCLUSION

Our findings revealed that Smad6 and Smad7 in GCF and saliva decreased in periodontitis and then increased after periodontal treatment. Our study suggests that I-Smads act in parallel with TGF-β in periodontal inflammation and may have a role in the development of periodontitis.

PRMT1-p53 Pathway Controls Epicardial EMT and Invasion

Epicardial cells are cardiac progenitors that give rise to the majority of cardiac fibroblasts, coronary smooth muscle cells, and pericytes during development. An integral phase of epicardial fate transition is epithelial-to-mesenchymal transition (EMT) that confers motility. We uncover an essential role for the protein arginine methyltransferase 1 (PRMT1) in epicardial invasion and differentiation. Using scRNA-seq, we show that epicardial-specific deletion of Prmt1 reduced matrix and ribosomal gene expression in epicardial-derived cell lineages. PRMT1 regulates splicing of Mdm4, which is a key controller of p53 stability. Loss of PRMT1 leads to accumulation of p53 that enhances Slug degradation and blocks EMT. During heart development, the PRMT1-p53 pathway is required for epicardial invasion and formation of epicardial-derived lineages: cardiac fibroblasts, coronary smooth muscle cells, and pericytes. Consequently, this pathway modulates ventricular morphogenesis and coronary vessel formation. Altogether, our study reveals molecular mechanisms involving the PRMT1-p53 pathway and establish its roles in heart development.

Polymicrobial communities in periodontal disease: Their quasi-organismal nature and dialogue with the host

In health, indigenous polymicrobial communities at mucosal surfaces maintain an ecological balance via both inter-microbial and host-microbial interactions that promote their own and the host's fitness, while preventing invasion by exogenous pathogens. However, genetic and acquired destabilizing factors (including immune deficiencies, immunoregulatory defects, smoking, diet, obesity, diabetes and other systemic diseases, and aging) may disrupt this homeostatic balance, leading to selective outgrowth of species with the potential for destructive inflammation. This process, known as dysbiosis, underlies the development of periodontitis in susceptible hosts. The pathogenic process is not linear but involves a positive-feedback loop between dysbiosis and the host inflammatory response. The dysbiotic community is essentially a quasi-organismal entity, where constituent organisms communicate via sophisticated physical and chemical signals and display functional specialization (eg, accessory pathogens, keystone pathogens, pathobionts), which enables polymicrobial synergy and dictates the community's pathogenic potential or nososymbiocity. In this review, we discuss early and recent studies in support of the polymicrobial synergy and dysbiosis model of periodontal disease pathogenesis. According to this concept, disease is not caused by individual "causative pathogens" but rather by reciprocally reinforced interactions between physically and metabolically integrated polymicrobial communities and a dysregulated host inflammatory response.

Arginine methylation of R81 in Smad6 confines BMP-induced Smad1 signaling

Bone morphogenetic proteins (BMPs) secreted by a variety of cell types are known to play essential roles in cell differentiation and matrix formation in the bone, cartilage, muscle, blood vessel, and neuronal tissue. BMPs activate intracellular effectors via C-terminal phosphorylation of Smad1, Smad5, and Smad9, which relay the signaling by forming a complex with Smad4 and translocate to the nucleus for transcriptional activation. Smad6 inhibits BMP signaling through diverse mechanisms operative at the membrane, cytosolic, and nuclear levels. However, the mechanistic underpinnings of Smad6 functional diversity remain unclear. Here, using a biochemical approach and cell differentiation systems, we report a cytosolic mechanism of action for Smad6 that requires arginine methylation at arginine 81 (R81) and functions through association with Smad1 and interference with the formation of Smad1–Smad4 complexes. By mutating the methylated arginine residue, R81, and by silencing the expression of protein arginine methyltransferase 1, we show that protein arginine methyltransferase 1 catalyzes R81 methylation of Smad6 upon BMP treatment, R81 methylation subsequently facilitates Smad6 interaction with the phosphorylated active Smad1, and R81 methylation facilitates Smad6-mediated interruption of Smad1–Smad4 complex formation and nuclear translocation. Furthermore, Smad6 WT but not the methylation-deficient R81A mutant inhibited BMP-responsive transcription, attenuated BMP-mediated osteogenic differentiation, and antagonized BMP-mediated inhibition of cell invasion. Taken together, our results suggest that R81 methylation plays an essential role in Smad6-mediated inhibition of BMP responses.

Interleukin 22 mitigates endothelial glycocalyx shedding after lipopolysaccharide injury

BACKGROUND

The endothelial glycocalyx (EG) on the luminal surface of endothelial cells contributes to the permeability barrier of vessels and prevents activation of the coagulation cascade. Endothelial glycocalyx damage, which occurs in the shock state, results in endotheliopathy. Interleukin (IL)-22 is a cytokine with both proinflammatory and anti-inflammatory properties, and how IL-22 affects the EG has not been studied. We hypothesized that IL-22:Fc, a recombinant fusion protein with human IL-22 and the Fc portion of human immunoglobulin G1 (which extends the protein half-life), would not affect EG shedding in endothelium after injury.

METHODS

Human umbilical vein endothelial cells (HUVECs) were exposed to 1 μg/mL lipopolysaccharide (LPS). Lipopolysaccharide-injured cells (n = 284) were compared with HUVECs with LPS injury plus 0.375 μg/mL of IL-22:Fc treatment (n = 293) for 12 hours. These two cohorts were compared with control HUVECs (n = 286) and HUVECs exposed to IL-22:Fc alone (n = 269). Cells were fixed and stained with fluorescein isothiocyanate-labeled wheat germ agglutinin to quantify EG. Total RNA was collected, and select messenger RNAs were quantified by real time - quantitative polymerase chain reaction (RT-qPCR) using SYBR green fluorescence.

RESULTS

Exposure of HUVECs to LPS resulted in degradation of the EG compared with control (5.86 vs. 6.09 arbitrary unit [AU], p = 0.01). Interleukin-22:Fc alone also resulted in degradation of EG (5.08 vs. 6.09 AU, p = 0.01). Treatment with IL-22:Fc after LPS injury resulted in less degradation of EG compared with LPS injury alone (5.86 vs. 5.08 AU, p = 0.002). Expression of the IL-22Ra1 receptor was not different for IL-22:Fc treated compared with LPS injury only (0.69 vs. 0.86 relative expression, p = 0.10). Treatment with IL-22:Fc after LPS injury resulted in less matrix metalloproteinase 2 (0.79 vs. 1.70 relative expression, p = 0.005) and matrix metalloproteinase 14 (0.94 vs. 2.04 relative expression, p = 0.02).

CONCLUSIONS

Interleukin-22:Fc alone induces EG degradation. However, IL-22:Fc treatment after LPS injury appears to mitigate EG degradation. This protective effect appears to be mediated via reduced expression of metalloproteinases.

Effects of chronic apical periodontitis on the inflammatory response of the aorta in hyperlipemic rats

OBJECTIVES

To study the effects of chronic apical periodontitis (CAP) on the inflammatory response and initial lesion of aorta in hyperlipemic rats.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats aged 14 weeks were randomly divided into 4 experimental groups (n = 8), namely, normal diet (ND), high-fat diet (HFD), CAP, and HFD + CAP. The rats were raised under controlled conditions and fed with diet specified for each group. All subjects were euthanatized after 14 weeks for histopathological analysis. Serum cytokines were analyzed to assess changes in gene and protein expression of aorta via enzyme-linked immunosorbent assay and real-time polymerase chain reaction. Results were analyzed by one-way ANOVA.

RESULTS

Low-density lipoprotein cholesterol levels in rats in HFD + CAP group were significantly higher than those in other groups. By comparison, low-density lipoprotein cholesterol levels in rats in both the HFD and HFD + CAP groups were significantly lower than those in the other groups. No significant difference among all groups was observed in terms of CRP level. However, levels of IL-2, IL-6, and IL-10 increased in the experimental CAP rats compared with the control rats. mRNA expression levels of MCP-1, TLR-4, and NF-κB p65 were markedly elevated in rats in the HFD group compared with those in rats in the ND group. TLR-4 mRNA expression was significantly higher in rats in the HFD + CAP group than that in rats in the HFD group.

CONCLUSIONS

CAP mediated the high expression of cytokines and induced the initial inflammatory response in the aorta. Apical periodontitis may affect the level of inflammatory cytokines (IL-2, IL-6, and IL-10) depending on the immune response.

CLINICAL RELEVANCE

CAP may trigger a systemic inflammatory response and affect the aorta of patients.

SMAD6 transduces endothelial cell flow responses required for blood vessel homeostasis

Fluid shear stress provided by blood flow instigates a transition from active blood vessel network expansion during development, to vascular homeostasis and quiescence that is important for mature blood vessel function. Here we show that SMAD6 is required for endothelial cell flow-mediated responses leading to maintenance of vascular homeostasis. Concomitant manipulation of the mechanosensor Notch1 pathway and SMAD6 expression levels revealed that SMAD6 functions downstream of ligand-induced Notch signaling and transcription regulation. Mechanistically, full-length SMAD6 protein was needed to rescue Notch loss-induced flow misalignment. Endothelial cells depleted for SMAD6 had defective barrier function accompanied by upregulation of proliferation-associated genes and down regulation of junction-associated genes. The vascular protocadherin PCDH12 was upregulated by SMAD6 and required for proper flow-mediated endothelial cell alignment, placing it downstream of SMAD6. Thus, SMAD6 is a required transducer of flow-mediated signaling inputs downstream of Notch1 and upstream of PCDH12, as vessels transition from an angiogenic phenotype to maintenance of a homeostatic phenotype.

The Ubiquitin Proteasome System in Periodontal Disease: A Comprehensive Review

The turnover of intracellular proteins is a highly selective and regulated process. This process is responsible for avoiding injury and irreparable breakdown of cellular constituents. Its impairment disrupts cellular stability, integrity, and homeostasis. The ubiquitin-proteasome system (UPS) is responsible for this programmed degradation of most intracellular proteins. This process involves a cascade of enzymes that involves the ubiquitin conjugation to a target substrate protein, its recognition and degradation by the proteasome. The turn-over of intracellular proteins is a non-stop ubiquitous process that regulates a series of mechanisms, for instance transcription, translation, endocytosis. In addition, proteasome act by releasing peptides that may serve to other purposes, such as antigen presentation in immune actions and enzymatic flagging toward biosynthesis and gluconeogenesis. The role of the UPS impairment in periodontal diseases is gaining growing. This acquaintance might contribute to the development of novel therapeutic applications. Thus, this review focuses on the latest progresses on the role of the UPS and its signaling pathways in Periodontal Medicine. Furthermore, we discuss the potential of UPS-based drugs development to be used in periodontal disease therapy.

A new anabolic compound, LLP2A-Ale, reserves periodontal bone loss in mice through augmentation of bone formation

BACKGROUND

Currently, there are no effective medications to reverse periodontal disease (PD)-induced bone loss. The objective of this study was to test a new anabolic compound, LLP2A-Ale, or with the combination treatment of mesenchymal stromal cell (MSC), in the treatment of bone loss secondary to PD.

METHODS

PD was induced in mice by placing a ligature around the second right molar. At one week after disease induction, the mice were treated with placebo, LLP2A-Ale, MSCs, or combination of LLP2A-Ale + MSCs, and euthanized at week 4.

RESULTS

We found that PD induced alveolar bone loss that was associated with reduced bone formation. LLP2A-Ale alone or in combination with MSCs sustained alveolar bone formation and reversed alveolar bone loss. Additionally, PD alone caused systemic inflammation and increased the circulating levels of G-CSF, IP-10, MIP-1a, and MIP2, which were suppressed by LLP2A-Ale +/- MSCs. LLP2A-Ale +/- MSCs increased bone formation at the peripheral skeletal site (distal femur), which was otherwise suppressed by PD.

CONCLUSION

Our findings indicated that LLP2A-Ale treatment rescued alveolar bone loss caused by PD, primarily by increasing bone formation. LLP2A-Ale also attenuated the circulating levels of a series of inflammatory cytokines and reversed the PD-induced suppression of systemic bone formation.

DNA methylation alterations and their potential influence on macrophage in periodontitis

OBJECTIVES

To explore how various methylation mechanisms function and affect macrophages in periodontitis, with an aim of getting a comprehensive understanding of pathogenesis of the disease.

SUBJECT

Alterations in DNA methylation are associated with different periodontitis susceptible factors and disrupt immunity homeostasis. The host's immune response to stimulus plays a vital role in the progression of periodontitis. Macrophages are key immune cells of immune system. They act as critical regulators in maintaining issue homeostasis with their nature of high plasticity. The altered methylation status of genes may cause abnormal expression of proteins in the progress of periodontitis, thus, exert potential influence on macrophages.

RESULTS

Certain genes are selectively activated or silenced due to the changes in the methylation status, which causes the alteration of the expression level of cytokines/chemokines, signal molecules, extracellular matrix molecules, leads to the change in local microenvironment, affects activation states of immune cells including macrophages, thus influences the host immune response during periodontitis.. This results in differential susceptibility and therapeutic outcome.

CONCLUSION

DNA methylation alteration may cause aberrant expression level of genes associated with periodontal diseases, thus results in deregulation of macrophages, which supports the prospect of using DNA methylation-related parameter as a new biomarker for the diagnosis and treatment of periodontitis.

The Role of DNA Methylation and Histone Modification in Periodontal Disease: A Systematic Review

Despite a number of reports in the literature on the role of epigenetic mechanisms in periodontal disease, a thorough assessment of the published studies is warranted to better comprehend the evidence on the relationship between epigenetic changes and periodontal disease and its treatment. Therefore, the aim of this systematic review is to identify and synthesize the evidence for an association between DNA methylation/histone modification and periodontal disease and its treatment in human adults. A systematic search was independently conducted to identify articles meeting the inclusion criteria. DNA methylation and histone modifications associated with periodontal diseases, gene expression, epigenetic changes after periodontal therapy, and the association between epigenetics and clinical parameters were evaluated. Sixteen studies were identified. All included studies examined DNA modifications in relation to periodontitis, and none of the studies examined histone modifications. Substantial variation regarding the reporting of sample sizes and patient characteristics, statistical analyses, and methodology, was found. There was some evidence, albeit inconsistent, for an association between DNA methylation and periodontal disease. IL6, IL6R, IFNG, PTGS2, SOCS1, and TNF were identified as candidate genes that have been assessed for DNA methylation in periodontitis. While several included studies found associations between methylation levels and periodontal disease risk, there is insufficient evidence to support or refute an association between DNA methylation and periodontal disease/therapy in human adults. Further research must be conducted to identify reproducible epigenetic markers and determine the extent to which DNA methylation can be applied as a clinical biomarker.

Fine-Tuning of GLI Activity through Arginine Methylation: Its Mechanisms and Function

The glioma-associated oncogene (GLI) family consists of GLI1, GLI2, and GLI3 in mammals. This family has important roles in development and homeostasis. To achieve these roles, the GLI family has widespread outputs. GLI activity is therefore strictly regulated at multiple levels, including via post-translational modifications for context-dependent GLI target gene expression. The protein arginine methyl transferase (PRMT) family is also associated with embryogenesis, homeostasis, and cancer mainly via epigenetic modifications. In the PRMT family, PRMT1, PRMT5, and PRMT7 reportedly regulate GLI1 and GLI2 activity. PRMT1 methylates GLI1 to upregulate its activity and target gene expression. Cytoplasmic PRMT5 methylates GLI1 and promotes GLI1 protein stabilization. Conversely, nucleic PRMT5 interacts with MENIN to suppress growth arrest-specific protein 1 expression, which assists Hedgehog ligand binding to Patched, indirectly resulting in downregulated GLI1 activity. PRMT7-mediated GLI2 methylation upregulates its activity through the dissociation of GLI2 and Suppressor of Fused. Together, PRMT1, PRMT5, and PRMT7 regulate GLI activity at multiple revels. Furthermore, the GLI and PRMT families have strong links with various cancers through cancer stem cell maintenance. Therefore, PRMT-mediated regulation of GLI activity would have important roles in cancer stem cell maintenance.

MiR-32-5p aggravates intestinal epithelial cell injury in pediatric enteritis induced by Helicobacter pylori

BACKGROUND

Pediatric enteritis is one of the infectious diseases in the digestive system that causes a variety of digestive problems, including diarrhea, vomiting, and bellyache in children. Clinically, Helicobacter pylori (H. pylori) infection is one of the common factors to cause pediatric enteritis. It has been demonstrated that aberrant expression of microRNAs (miRNAs) is found in gastrointestinal diseases caused by H. pylori, and we discovered a significant increase of miR-32-5p in H. pylori-related pediatric enteritis. However, the exact role of miR-32-5p in it is still unknown.

AIM

To investigate the role of aberrant miR-32-5p in pediatric enteritis induced by H. pylori.

METHODS

MiR-32-5p expression was detected by quantitative real time-polymerase chain reaction. The biological role of miR-32-5p in H. pylori-treated intestinal epithelial cells was evaluated by Cell Counting Kit-8 assay and flow cytometry. The potential target of miR-32-5p was predicted with TargetScanHuman and verified by luciferase assay. The downstream mechanism of miR-32-5p was explored by using molecular biology methods.

RESULTS

We found that miR-32-5p was overexpressed in serum of H. pylori-induced pediatric enteritis. Further investigation revealed that H. pylori infection promoted the death of intestinal epithelial cells, and increased miR-32-5p expression. Moreover, miR-32-5p mimic further facilitated apoptosis and inflammatory cytokine secretion of intestinal epithelial cells. Further exploration revealed that SMAD family member 6 (SMAD6) was the direct target of miR-32-5p, and SMAD6 overexpression partially rescued cell damage induced by H. pylori. The following experiments showed that miR-32-5p/SMAD6 participated in the apoptosis of intestinal epithelial cells induced by transforming growth factor-β-activated kinase 1 (TAK1)-p38 activation under H. pylori infection.

CONCLUSION

Our work uncovered the crucial role of aberrant expression of miR-32-5p in H. pylori–related pediatric enteritis, and suggested that the TAK1-p38 pathway is involved in it.

Crosstalk between histone modification and DNA methylation orchestrates the epigenetic regulation of the costimulatory factors, Tim‑3 and galectin‑9, in cervical cancer

Persistent infection with high-risk human papillomavirus is known to cause cervical cancer. The binding of the costimulatory factors, Tim-3 and galectin-9, can cause immune tolerance and lead to immune escape during carcinogenesis. Epigenetic regulation is essential for Tim-3/galectin-9 expression, which affects the outcome of local cervical cancer infection. Hence, exploring the epigenetic regulatory mechanisms of costimulatory signaling by Tim-3/galectin-9 is of great interest for investigating the mechanisms through which these proteins are regulated in cervical cancer tumorigenesis. In this study, we report that E2F-1 and FOXM1 mediated by HPV18 E6 and E7 can enhance the transcriptional activity of Enhancer of zeste homolog 2 (EZH2) by binding to its promoter region, resulting in the induced expression of the EZH2-specific target protein, H3K27me3, which consequently reduces the expression of the downstream target gene, DNA (cytosine-5)-methyltransferase 3A (DNMT3A). EZH2 and H3K27me3 directly interact with the DNMT3A promoter region to negatively regulate its expression in HeLa cells. Moreover, the downregulated DNMT3A and the decreased methylation levels in HAVCR2/LGALS9 promoter regions in HeLa cells promoted the expression of Tim-3/galectin-9. Furthermore, the high expression of Tim-3/galectin-9 was associated with HPV positivity among patients with cervical cancer. Moreover, HAVCR2/LGALS9 promoter regions were hypermethylated in normal cervical tissues, and this hypermethylated status inhibited gene expression. On the whole, these findings suggest that EZH2, H3K27me3 and DNMT3A mediate the epigenetic regulation of the negative stimulatory molecules, Tim-3 and galectin-9 in cervical cancer which is associated with HPV18 infection.

The regulation, functions and clinical relevance of arginine methylation

Methylation of arginine residues by protein arginine methyltransferases (PRMTs) is involved in the regulation of fundamental cellular processes, including transcription, RNA processing, signal transduction cascades, the DNA damage response and liquid-liquid phase separation. Recent studies have provided considerable advances in the development of experimental tools and the identification of clinically relevant PRMT inhibitors. In this review, we discuss the regulation of PRMTs, their various cellular roles and the clinical relevance of PRMT inhibitors for the therapy of neurodegenerative diseases and cancer.

Epigenetic Approaches to the Treatment of Dental Pulp Inflammation and Repair: Opportunities and Obstacles

Concerns over the cost and destructive nature of dental treatment have led to the call for novel minimally invasive, biologically based restorative solutions. For patients with toothache, this has resulted in a shift from invasive root-canal-treatment (RCT) toward more conservative vital-pulp-treatment (VPT) procedures, aimed to protect the pulp and harness its natural regenerative capacity. If the dental pulp is exposed, as long as the infection and inflammation can be controlled, conservative therapies can promote the formation of new tertiary dentine in a stem cell-led reparative process. Crucially, the volume and quality of new dentine is dependent on the material applied; however, currently available dental-materials are limited by non-specific action, cytotoxicity and poor clinical handling. Looking to the future, an improved understanding of the cellular regulators of pulpal inflammation and associated repair mechanisms is critical to predict pulpal responses and devise novel treatment strategies. Epigenetic modifications of DNA-associated proteins and the influences of non-coding RNAs have been demonstrated to control the self-renewal of stem cell populations as well as regulate mineralised tissue development and repair. Notably, the stability of microRNAs and their relative ease of sampling from pulpal blood highlight their potential for application as diagnostic inflammatory biomarkers, while increased understanding of their actions will not only enhance our knowledge of pulpal disease and repair, but also identify novel molecular targets. The potential therapeutic application of epigenetic modifying agents, DNA-methyltransferase-inhibitors (DNMTi) and histone-deacetylase-inhibitors (HDACi), have been shown to promote mineralisation and repair processes in dental-pulp-cell (DPC) populations as well as induce the release of bioactive dentine-matrix-components. Consequently, HDACis and DNMTis have the potential to enhance tertiary dentinogenesis by influencing the cellular and tissue processes at low concentrations with minimal side effects, providing an opportunity to develop a topically placed, inexpensive bio-inductive restorative material. The aim of this review is to highlight the potential role of epigenetic approaches in the treatment of the damaged dental pulp, considering the opportunities and obstacles, such as off-target effects, delivery mechanisms, for the therapeutic use of miRNA as an inflammatory biomarker or molecular target, before discussing the application of HDACi and DNMTi to the damaged pulp to stimulate repair.

Arginine methylation of SMAD7 by PRMT1 in TGF-β-induced epithelial-mesenchymal transition and epithelial stem-cell generation

The epithelial-to-mesenchymal transdifferentiation (EMT) is crucial for tissue differentiation in development and drives essential steps in cancer and fibrosis. EMT is accompanied by reprogramming of gene expression and has been associated with the epithelial stem-cell state in normal and carcinoma cells. The cytokine transforming growth factor β (TGF-β) drives this program in cooperation with other signaling pathways and through TGF-β-activated SMAD3 as the major effector. TGF-β-induced SMAD3 activation is inhibited by SMAD7 and to a lesser extent by SMAD6, and SMAD6 and SMAD7 both inhibit SMAD1 and SMAD5 activation in response to the TGF-β-related bone morphogenetic proteins (BMPs). We previously reported that, in response to BMP, protein arginine methyltransferase 1 (PRMT1) methylates SMAD6 at the BMP receptor complex, thereby promoting its dissociation from the receptors and enabling BMP-induced SMAD1 and SMAD5 activation. We now provide evidence that PRMT1 also facilitates TGF-β signaling by methylating SMAD7, which complements SMAD6 methylation. We found that PRMT1 is required for TGF-β-induced SMAD3 activation, through a mechanism similar to that of BMP-induced SMAD6 methylation, and thus promotes the TGF-β-induced EMT and epithelial stem-cell generation. This critical mechanism positions PRMT1 as an essential mediator of TGF-β signaling that controls the EMT and epithelial cell stemness through SMAD7 methylation.