Secretory leukocyte protease inhibitor reduces inflammation and alveolar bone resorption in LPS-induced periodontitis in rats and in MC3T3-E1 preosteoblasts

In periodontitis, alveolar bone resorption is induced by excessive host immune and inflammatory response against bacterial infection. Secretory leukocyte protease inhibitor (SLPI) has anti-bacterial and anti-inflammatory activity in inflammatory responses. SLPI inhibits joint inflammation and bone destruction, but the function of SLPI in periodontitis is unclear. Therefore, this study investigated whether SLPI inhibits the inflammatory response and alveolar bone resorption in LPS-induced periodontitis of rats. Micro-computed tomography and histological analysis showed that SLPI inhibited alveolar bone resorption by LPS-induced periodontitis. Immunohistochemistry revealed that SLPI decreased tumor necrosis factor-α (TNF-α) and interleukine-1β (IL-1β) expression in periodontitis tissue, and decreased mRNA and protein expression of TNF-α and IL-1β in LPS-stimulated MC3T3-E1 cells. The results indicated that SLPI reduced alveolar bone resorption in LPS-induced periodontitis and inhibited inflammatory cytokine, such as TNF-α and IL-1β, expression in LPS-stimulated MC3T3-E1 preosteoblasts. Therefore, SLPI could be a regulatory molecule by inhibiting alveolar bone resorption through the reduction of inflammatory cytokines, and inducing osteoblast activation for bone formation.     

NLRP3 regulates alveolar bone loss in ligature‐induced periodontitis by promoting osteoclastic differentiation

ObjectivesNLRP3 inflammasome is a critical part of the innate immune system and plays an important role in a variety of inflammatory diseases. However, the effects of NLRP3 inflammasome on periodontitis have not been fully studied.Materials and methodsWe used ligature‐induced periodontitis models of NLRP3 knockout mice (NLRP3^KO) and their wildtype (WT) littermates to compare their alveolar bone phenotypes. We further used Lysm‐Cre/Rosa^nTnG mouse to trace the changes of Lysm‐Cre⁺ osteoclast precursors in ligature‐induced periodontitis with or without MCC950 treatment. At last, we explored MCC950 as a potential drug for the treatment of periodontitis in vivo and in vitro.ResultsHere, we showed that the number of osteoclast precursors, osteoclast differentiation and alveolar bone loss were reduced in NLRP3^KO mice compared with WT littermates, by using ligature‐induced periodontitis model. Next, MCC950, a specific inhibitor of the NLRP3 inflammasome, was used to inhibit osteoclast precursors differentiation into osteoclast. Further, we used Lysm‐Cre/Rosa^nTnG mice to demonstrate that MCC950 decreases the number of Lysm‐Cre⁺ osteoclast precursors in ligature‐induced periodontitis. At last, treatment with MCC950 significantly suppressed alveolar bone loss with reduced IL‐1β activation and osteoclast differentiation in ligature‐induced periodontitis.ConclusionOur findings reveal that NLRP3 regulates alveolar bone loss in ligature‐induced periodontitis by promoting osteoclastic differentiation.     

Emerging complexity and new roles for the RIG-I-like receptors in innate antiviral immunity

Innate immunity is critical for the control of virus infection and operates to restrict viral susceptibility and direct antiviral immunity for protection from acute or chronic viral-associated diseases including cancer. RIG-I like receptors (RLRs) are cytosolic RNA helicases that function as pathogen recognition receptors to detect RNA pathogen associated molecular patterns (PAMPs) of virus infection. The RLRs include RIG-I, MDA5, and LGP2. They function to recognize and bind to PAMP motifs within viral RNA in a process that directs the RLR to trigger downstream signaling cascades that induce innate immunity that controls viral replication and spread. Products of RLR signaling also serve to modulate the adaptive immune response to infection. Recent studies have additionally connected RLRs to signaling cascades that impart inflammatory and apoptotic responses to virus infection. Viral evasion of RLR signaling supports viral outgrowth and pathogenesis, including the onset of viral-associated cancer.     

Essential roles of RNA cap-proximal ribose methylation in mammalian embryonic development and fertility

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益生菌联合牙周基础治疗对慢性牙周炎患者口腔致病菌的影响

目的 探讨益生菌联合牙周基础治疗对慢性牙周炎患者的治疗效果及其对口腔致病菌的影响。 方法 选取2017年10月至2019年4月我院收治的120例慢性牙周炎患者为研究对象,采用随机数字法将其分为对照组(n=60)及观察组(n=60),对照组采取牙周基础治疗,包括对牙垢面进行清洁、处理咬合创伤、采用生理盐水漱口等及口服阿莫西林胶囊、甲硝唑片,观察组在对照组的基础上口服双歧杆菌三联活菌胶囊,2粒/次,2次/d。治疗4周后,比较2组研究对象探诊深度(probing depth,PD)、牙菌斑指数(dental plaque index,PLI)及牙龈出血指数(bleeding index,BI),评估治疗效果;采用细菌培养的方式观察龈沟液中主要致病菌群变化情况,并记录不良反应发生情况。 结果 治疗后,观察组研究对象PD、PLI及BI均低于对照组(t=2.614,P=0.010;t=2.523,P=0.013;t=5.330,P2=6.775,P=0.009);治疗后,2组研究对象唾液中福赛坦菌、中间普氏菌、牙龈卟啉单胞菌以及伴放线放线杆菌检出率均低于对照组(t=4.174,P=0.041;t=5.783,P=0.016;t=6.009,P=0.014;t=10.231,P=0.001);2组研究对象不良反应发生率差异无统计学意义(χ2=0.086,P=0.769)。 结论 在牙周基础治疗上口服双歧杆菌三联活菌胶囊有利于减轻慢性牙周炎患者牙周症状、抑制口腔致病菌、提高治疗效果。     

Mesenchymal stem cells in tumor development: Emerging roles and concepts

Mesenchymal stem cells (MSCs) are multipotent progenitor cells that participate in the structural and functional maintenance of connective tissues under normal homeostasis. They also act as trophic mediators during tissue repair, generating bioactive molecules that help in tissue regeneration following injury. MSCs serve comparable roles in cases of malignancy and are becoming increasingly appreciated as critical components of the tumor microenvironment. MSCs home to developing tumors with great affinity, where they exacerbate cancer cell proliferation, motility, invasion and metastasis, foster angiogenesis, promote tumor desmoplasia and suppress anti-tumor immune responses. These multifaceted roles emerge as a product of reciprocal interactions occurring between MSCs and cancer cells and serve to alter the tumor milieu, setting into motion a dynamic co-evolution of both tumor and stromal tissues that favors tumor progression. Here, we summarize our current knowledge about the involvement of MSCs in cancer pathogenesis and review accumulating evidence that have placed them at the center of the pro-malignant tumor stroma.     

Galectins in teleost fish: Zebrafish (Danio rerio) as a model species to address their biological roles in development and innate immunity

Cell surface glycans, such as glycocoproteins and glycolipids, encode information that modulates interactions between cells, or between cells and the extracellular matrix, by specifically regulating the binding to cell surface-associated or soluble carbohydrate-binding receptors, such as lectins. Rapid modifications of exposed carbohydrate moieties by glycosidases and glycosyltransferases, and the equally dynamic patterns of expression of their receptors during early development, suggest that both play important roles during embryogenesis. Among a variety of biological roles, galectins have been proposed to mediate developmental processes, such as embryo implantation and myogenesis. However, the high functional redundancy of the galectin repertoire in mammals has hindered the rigorous characterization of their specific roles by gene knockout approaches in murine models. In recent years, the use of teleost fish as alternative models for addressing developmental questions in mammals has expanded dramatically, and we propose their use for the elucidation of biological roles of galectins in embryogenesis and innate immunity. All three major galectin types, proto, chimera, and tandem-repeat, are present in teleost fish, and phylogenetic topologies confirm the expected clustering with their mammalian orthologues. As a model organism, the zebrafish (Danio rerio) may help to overcome limitations imposed by the murine models because it offers substantial advantages: external fertilization, transparent embryos that develop rapidly in vitro, a diverse toolbox of established methods to manipulate early gene expression, a growing collection of mutations that affect early embryonic development, availability of cell lines, and most importantly, an apparently less diversified galectin repertoire. Published in 2004.     

皮肤共生菌在皮肤健康和疾病中的作用研究进展

人体皮肤上有多种微生物定居,这些微生物群落的组成、分布和动态变化对皮肤的健康状况和疾病有着重要的调节作用.然而,人们一直不清楚皮肤微生物群落如何影响人类健康.对皮肤共生菌进行深入研究,不仅有助于发现有益皮肤共生菌菌株,也有助于筛选相应皮肤疾病新的药物靶标.近年来,对皮肤共生菌与宿主之间相互影响和作用机制的研究逐渐深入,...     

Recent advances in the biology of IL-1 family cytokines and their potential roles in development of sepsis

The IL-1 family comprises two anti-inflammatory cytokines (IL-37, IL-38), two receptor antagonists (IL-1ra, IL-36ra), and seven ligand agonists (IL-1α, IL-1β, IL-33, IL-36α, IL-36β, IL-36γ). The members of this family exert pleiotropic effects on intercellular signaling, leading to pro- or anti-inflammatory responses. They initiate potent inflammatory and immune responses by binding to specific receptors in the IL-1 receptor family, and their activities are repressed by naturally occurring inhibitors. Various immune cells produce and are regulated by these crucial molecules, which appear to be involved in the pathogenesis of diverse diseases including cancer as well as inflammatory and autoimmune disorders. Recent decades have seen substantial progress in understanding how the IL-1 family contributes to the development of sepsis. In this review, we will briefly introduce the IL-1 family and discuss its critical role in inflammatory and immune responses. The potential significance of IL-1 members in sepsis will also be explored, together with the clinical implications for treating this dangerous condition.     

Inhibition of SARS-CoV-2 Infection by Human Defensin HNP1 and Retrocyclin RC-101

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 is an enveloped virus responsible for the COVID-19 pandemic. The emergence of new potentially more transmissible and vaccine-resistant variants of SARS-CoV-2 is an ever-present threat. Thus, it remains essential to better understand innate immune mechanisms that can inhibit the virus. One component of the innate immune system with broad antipathogen, including antiviral, activity is a group of cationic immune peptides termed defensins. The ability of defensins to neutralize enveloped and non-enveloped viruses and to inactivate numerous bacterial toxins correlate with their ability to promote the unfolding of proteins with high conformational plasticity. We found that human neutrophil α-defensin HNP1 binds to SARS-CoV-2 Spike protein with submicromolar affinity that is more than 20 fold stronger than its binding to serum albumin. As such, HNP1, as well as a θ-defensin retrocyclin RC-101, both interfere with Spike-mediated membrane fusion, Spike-pseudotyped lentivirus infection, and authentic SARS-CoV-2 infection in cell culture. These effects correlate with the abilities of the defensins to destabilize and precipitate Spike protein and inhibit the interaction of Spike with the ACE2 receptor. Serum reduces the anti-SARS-CoV-2 activity of HNP1, though at high concentrations, HNP1 was able to inactivate the virus even in the presence of serum. Overall, our results suggest that defensins can negatively affect the native conformation of SARS-CoV-2 Spike, and that α- and θ-defensins may be valuable tools in developing SARS-CoV-2 infection prevention strategies.     

Tyrosine‐protein phosphatase non‐receptor type 2 inhibits alveolar bone resorption in diabetic periodontitis via dephosphorylating CSF1 receptor

Tyrosine‐protein phosphatase non‐receptor type 2 (PTPN2) is an important protection factor for diabetes and periodontitis, but the underlying mechanism remains elusive. This study aimed to identify the substrate of PTPN2 in mediating beneficial effects of 25‐Hydroxyvitamin D₃ (25(OH)2D₃) on diabetic periodontitis. 25(OH)2D₃ photo‐affinity probe was synthesized with the minimalist linker and its efficacy to inhibit alveolar bone loss, and inflammation was evaluated in diabetic periodontitis mice. The probe was used to pull down the lysates of primary gingival fibroblasts. We identified PTPN2 as a direct target of 25(OH)2D₃, which effectively inhibited inflammation and bone resorption in diabetic periodontitis mice. In addition, we found that colony‐stimulating factor 1 receptor (CSF1R) rather than JAK/STAT was the substrate of PTPN2 to regulate bone resorption. PTPN2 direct interacted with CSF1R and dephosphorylated Tyr807 residue. In conclusion, PTPN2 dephosphorylates CSF1R at Y807 site and inhibits alveolar bone resorption in diabetic periodontitis mice. PTPN2 and CSF1R are potential targets for the therapy of diabetic periodontitis or other bone loss‐related diseases.     

Insights into the molecular basis of the NOD2 signalling pathway

The cytosolic pattern recognition receptor NOD2 is activated by the peptidoglycan fragment muramyl dipeptide to generate a proinflammatory immune response. Downstream effects include the secretion of cytokines such as interleukin 8, the upregulation of pro-interleukin 1β, the induction of autophagy, the production of antimicrobial peptides and defensins, and contributions to the maintenance of the composition of the intestinal microbiota. Polymorphisms in NOD2 are the cause of the inflammatory disorder Blau syndrome and act as susceptibility factors for the inflammatory bowel condition Crohn''s disease. The complexity of NOD2 signalling is highlighted by the observation that over 30 cellular proteins interact with NOD2 directly and influence or regulate its functional activity. Previously, the majority of reviews on NOD2 function have focused upon the role of NOD2 in inflammatory disease or in its interaction with and response to microbes. However, the functionality of NOD2 is underpinned by its biochemical interactions. Consequently, in this review, we have taken the opportunity to address the more ‘basic’ elements of NOD2 signalling. In particular, we have focused upon the core interactions of NOD2 with protein factors that influence and modulate the signal transduction pathways involved in NOD2 signalling. Further, where information exists, such as in relation to the role of RIP2, we have drawn comparison with the closely related, but functionally discrete, pattern recognition receptor NOD1. Overall, we provide a comprehensive resource targeted at understanding the complexities of NOD2 signalling.     

Emerging roles of PHLPP phosphatases in metabolism

Over the last decades, research has focused on the role of pleckstrin homology (PH) domain leucine-rich repeat protein phosphatases (PHLPPs) in regulating cellular signaling via PI3K/Akt inhibition. The PKB/Akt signaling imbalances are associated with a variety of illnesses, including various types of cancer, inflammatory response, insulin resistance, and diabetes, demonstrating the relevance of PHLPPs in the prevention of diseases. Furthermore, identification of novel substrates of PHLPPs unveils their role as a critical mediator in various cellular processes. Recently, researchers have explored the increasing complexity of signaling networks involving PHLPPs whereby relevant information of PHLPPs in metabolic diseases was obtained. In this review, we discuss the current knowledge of PHLPPs on the well-known substrates and metabolic regulation, especially in liver, pancreatic beta cell, adipose tissue, and skeletal muscle in relation with the stated diseases. Understanding the context-dependent functions of PHLPPs can lead to a promising treatment strategy for several kinds of metabolic diseases.     

Emerging roles of Orai3 in pathophysiology

Calcium (Ca²⁺) is a ubiquitous second messenger that regulates a plethora of physiological functions. Deregulation of calcium homeostasis has been reported in a wide variety of pathological conditions including cardiovascular disorders, cancer and neurodegenerative diseases. One of the most ubiquitous pathways involved in regulated Ca²⁺ influx into cells is the store-operated Ca²⁺ entry (SOCE) pathway. In 2006, Orai1 was identified as the channel protein that mediates SOCE in immune cells. Orai1 has two mammalian homologs, Orai2 and Orai3. Although Orai1 has been the most widely studied Orai isoform, Orai3 has recently received significant attention. Under native conditions, Orai3 was demonstrated to be an important component of store-independent arachidonate-regulated Ca²⁺ (ARC) entry in HEK293 cells, and more recently of a store-independent leukotrieneC₄-regulated Ca²⁺ (LRC) entry pathway in vascular smooth muscle cells. Recent studies have shown upregulation of Orai3 in estrogen receptor-expressing breast cancers and a critical role for Orai3 in breast cancer development in immune-compromised mice. Orai3 upregulation was also shown to contribute to vascular smooth muscle remodeling and neointimal hyperplasia caused by vascular injury. Furthermore, Orai3 has been shown to contribute to proliferation of effector T-lymphocytes under oxidative stress. In this review, we will discuss the role of Orai3 in reported pathophysiological conditions and will contribute ideas on the potential role of Orai3 in native Ca²⁺ signaling pathways and human disease.     

Detection and characterization of beta-lactamase genes in subgingival bacteria from patients with refractory periodontitis

Fifty-three beta-lactamase-producing strains of oral bacteria isolated from patients with refractory periodontitis in Norway and USA were screened for the presence of the bla(TEM), bla(SHV), bla(OXA), bla(ampC), bla(cfxA), and bla(cepA/cblA) genes by the polymerase chain reaction (PCR). The PCR products were characterized by direct sequencing of the amplified DNA. Thirty-four of the 53 enzyme-producing strains (64%) were positive in one of the PCR assays. All beta-lactamase-producing Prevotella and Capnocytophaga spp. were CfxA positive. TEM-type beta-lactamases were identified in one strain each of Escherichia coli and Neisseria sp., and one strain of Citrobacter freundii possessed an AmpC-type beta-lactamase. Screening for gene cassettes and genes known to be associated with integrons did not reveal the presence of integrons in these oral bacteria. Sequence analyses showed that most CfxA positive Prevotella and Capnocytophaga isolates from patients with refractory periodontitis harboured variants of the CfxA2 and CfxA3 enzyme. The present study also showed that many different genetic determinants of beta-lactamase production are found in bacteria isolated from refractory periodontitis, many of which remain to be characterized.     

Phylogenetic and functional gene structure shifts of the oral microbiomes in periodontitis patients

Determining the composition and function of subgingival dental plaque is crucial to understanding human periodontal health and disease, but it is challenging because of the complexity of the interactions between human microbiomes and human body. Here, we examined the phylogenetic and functional gene differences between periodontal and healthy individuals using MiSeq sequencing of 16S rRNA gene amplicons and a specific functional gene array (a combination of GeoChip 4.0 for biogeochemical processes and HuMiChip 1.0 for human microbiomes). Our analyses indicated that the phylogenetic and functional gene structure of the oral microbiomes were distinctly different between periodontal and healthy groups. Also, 16S rRNA gene sequencing analysis indicated that 39 genera were significantly different between healthy and periodontitis groups, and Fusobacterium, Porphyromonas, Treponema, Filifactor, Eubacterium, Tannerella, Hallella, Parvimonas, Peptostreptococcus and Catonella showed higher relative abundances in the periodontitis group. In addition, functional gene array data showed that a lower gene number but higher signal intensity of major genes existed in periodontitis, and a variety of genes involved in virulence factors, amino acid metabolism and glycosaminoglycan and pyrimidine degradation were enriched in periodontitis, suggesting their potential importance in periodontal pathogenesis. However, the genes involved in amino acid synthesis and pyrimidine synthesis exhibited a significantly lower relative abundance compared with healthy group. Overall, this study provides new insights into our understanding of phylogenetic and functional gene structure of subgingival microbial communities of periodontal patients and their importance in pathogenesis of periodontitis.     

Vascular traffic control of neutrophil recruitment to the liver by microbiota-endothelium crosstalk

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