The SloR metalloregulator is involved in the Streptococcus mutans oxidative stress response

SloR, a 25‐kDa metalloregulatory protein in Streptococcus mutans modulates the expression of multiple genes, including the sloABC operon that encodes essential Mn²⁺ transport and genes that promote cariogenesis. In this study, we report on SloC‐ and SloR‐deficient strains of S. mutans (GMS284 and GMS584, respectively) that demonstrate compromised survivorship compared with their UA159 wild‐type progenitor and their complemented strains (GMS285 and GMS585, respectively), when challenged with streptonigrin and/or in growth competition experiments. The results of streptonigrin assays revealed significantly larger zones of inhibition for GMS584 than for either UA159 or GMS585, indicating weakened S. mutans survivorship in the absence of SloR. Competition assays revealed a compromised ability for GMS284 and GMS584 to survive peroxide challenge compared with their SloC‐ and SloR‐proficient counterparts. These findings are consistent with a role for SloC and SloR in S. mutans aerotolerance. We also predicted differential expression of oxidative stress tolerance genes in GMS584 versus UA159 and GMS585 when grown aerobically. The results of quantitative RT‐PCR experiments revealed S. mutans sod, tpx, and sloC expression that was upregulated in GMS584 compared with UA159 and GMS585, indicating that the impact of oxidative stress on S. mutans is more severe in the absence of SloR than in its presence. The results of electrophoretic mobility shift assays indicate that SloR does not bind to the sod or tpx promoter regions directly, implicating intermediaries that may arbitrate the SloR response to oxidative stress.     

Periodontitis as an infectious disease: specific features and their implications

Periodontitis may be viewed as an infectious disease with a number of specific characteristics. Pathogens of the subgingival microbiota can interact with host tissues even without direct tissue penetration. Hence, antimicrobial agents must be available at a sufficiently high concentration not only within the periodontal tissues, but also outside, in the environment of the periodontal pocket. The subgingival microbiota accumulate on the root surface to form an adherent layer of plaque with the characteristics of a biofilm. Several mechanisms, such as diffusion barriers, and selective inactivation of agents lead to an increased resistance of bacteria in biofilms. Mechanical supragingival plaque control is indispensable to prevent the re-emergence of periodontal pathogens and the re-establishment of a biofilm in treated sites. Since specific features have important implications for the use of antimicrobial agents in periodontal therapy, extrapolations from experiences made in the therapy of other infections are only partially valid. The ultimate evidence for the efficacy of systemic or local chemotherapy must be obtained from treatment studies in humans with adequate follow-up.     

氧化应激在糖尿病相关性牙周炎发病中的作用

在糖尿病相关性牙周炎发病机制的研究中,糖尿病患者中长期慢性的高糖状态可能通过多个途径诱发氧化应激,局部产生大量的活性氧族(ROS),而ROS可改变信号传导通路引起炎症反应因子的基因和蛋白质表达异常,导致机体炎症应答大大增强,促使牙周炎症发生.本文就高血糖诱发氧化应激的可能途径、氧化应激作用机制、抗氧化物在糖尿病相关性牙...     

Evidence of oxidative stress in temporomandibular disorders: a pilot study

Oxidative stress is involved in the pathogenesis of many conditions and is caused by free radicals in concentrations that overwhelm the natural scavenging mechanisms and cause pain and inflammation. This investigation sought to determine whether pain from temporomandibular disorders was associated with increased oxidative stress as measured by biomarkers in saliva and serum. Both salivary and serum levels of the oxidative stress biomarkers including 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were compared in patients with mild and severe TMJD pain and with healthy controls. These biomarkers were determined spectrophotometrically in saliva and serum from 10 high TMJD pain patients, 10 low TMJD pain patients, and 10 healthy control subjects from National Institute of Dental Research's TMJ Implant Registry and Repository. Linear and logistic regression analyses were used to evaluate the association between each biomarker and TMJD pain. The mean levels of log 8-hydroxydeoxyguanosine (saliva P < 0·0001, serum P = 0·0008), malondialdehyde (saliva P = 0·002, serum P = 0·004) and total antioxidant status (saliva P = 0·005; serum P = 0·001) achieved statistically significant differences between groups. In linear regression analysis, both salivary and serum levels of each biomarker were associated with TMJD pain. In a multivariable analysis, again, both salivary levels and serum levels were also different between groups. Salivary levels of oxidative stress ratios of 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were significantly different between patients with TMJD pain and controls and was comparable to that in serum. These biomarkers hold promise as a potential diagnostic and therapeutic strategy.     

睡眠剥夺对大鼠咬肌氧化应激指标的影响

目的：观察睡眠剥夺后大鼠咬肌组织氧化应激相关物质的变化，探讨睡眠剥夺在颞下颌关节紊乱病发病中的作用。方法：35只Wistar大鼠，随机分为5组：睡眠剥夺1d组、5d组、9d组、正常对照组和大平台对照组。采用改良多平台睡眠剥夺法（modified multipleplat-formmethod，MMPM）建立大鼠睡眠剥夺模型，观察睡眠剥夺对咬肌组织中超氧化物歧化酶（SOD）、谷胱甘肽一过氧化物酶（GSH-PX）、过氧化氢酶（CAT）活性及丙二醛（MDA）、还原型谷胱甘肽（GSH）、过氧化氢（H2O2）含量的影响。结果：与正常对照组和大平台对照组相比，睡眠剥夺后大鼠咬肌组织中MDA、GSH及H2O2的含量明显升高（P〈0．05），且随着睡眠剥夺时间的延长有明显上升的趋势；而SOD、GSH—PX及CAT的活性随睡眠剥夺时间的延长有降低的趋势。结论：睡眠剥夺可引起大鼠咬肌发生明显的氧化应激反应，这可能是颢下颌关节紊乱病的致病因素之一。     

氧化应激诱发糖尿病性牙周炎作用及机制

糖尿病和牙周炎有双向关系,二者间作用机制尚不清楚。糖尿病长期高糖状态可诱发氧化应激(oxidative stress,OS)反应,产生大量活性氧族(ROS),可通过改变信号传导通路等途径引起炎症因子基因和蛋白质表达异常,导致炎症反应增强,破坏牙周组织。该文从OS诱发糖尿病性牙周炎作用、OS诱发糖尿病性牙周炎机制、抗氧化物治疗及前景等方面进行研究,为糖尿病性牙周炎治疗和研究提供依据。     

The bcp gene in the bcp-recA-vimA-vimE-vimF operon is important in oxidative stress resistance in Porphyromonas gingivalis W83

The ability of Porphyromonas gingivalis to overcome oxidative stress in the inflammatory environment of the periodontal pocket is critical for its survival. We have previously demonstrated that the recA locus, which carries the bacterioferritin co-migratory protein (bcp) gene and has a unique genetic architecture, plays a role in virulence regulation and oxidative stress resistance in P. gingivalis. To further characterize the bcp gene, which was confirmed to be part of the bcp-recA-vimA-vimE-vimF operon, we created a P. gingivalis bcp-defective isogenic mutant (FLL302) by allelic exchange. Compared with the wild-type, FLL302 had a similar growth rate, black pigmentation, β-hemolysis and UV sensitivity. Although there was no change in the distribution of gingipain activity, there was a 30% reduction in both Arg-X and Lys-X activities in the mutant strain compared with the wild-type. When exposed to 0.25 mm hydrogen peroxide, P. gingivalis FLL302 was more sensitive than the wild-type. In addition, the cloned P. gingivalis bcp gene increased resistance to 0.25 mm hydrogen peroxide in a bcp-defective Escherichia coli mutant. The mutant also demonstrated decreased aerotolerance when compared with the wild-type. Porphyromonas gingivalis FLL302 and the wild-type strain had similar virulence profiles in a mouse model of virulence. These observations suggest that the bcp gene may play a role in oxidative stress resistance but has a decreased functional significance in the pathogenic potential of P. gingivalis.     

Parameters of oxidative stress in saliva from diabetic and parenteral drug addict patients

BACKGROUND: Oxidative stress constitutes the basis for many diseases and it may account for the severity of systemic and oral disease complications. The aim of this study was to assess whether saliva may be used to detect the body's oxidative stress level. METHODS: Oxidative stress was determined in saliva from 14 diabetic patients and 10 heroin addicts; two different pathologic conditions related to free radical damage, and 21 healthy control subjects were included in the study. Glutathione peroxidase (GPx) and reductase (GRd) activities, and glutathione (GSH) and glutathione disulfide (GSSG) levels were analyzed in the saliva of all individuals. Other variables including salivary volume and the oral status were also analyzed. RESULTS: Diabetic patients had GPx and GRd activities of 39.98 +/- 1.61 and 6.19 +/- 0.61 nmol/min/mg prot, respectively. These values were significantly higher (P < 0.001) than those obtained in control saliva (27.51 +/- 0.86 and 3.44 +/- 0.25 nmol/min/mg prot, respectively). Drug addicts showed significantly (P < 0.001) lower salivary GPx and GRd activities than controls. Both group of patients had significantly lower levels of GSH and higher of GSSG than controls (P < 0.001). CONCLUSIONS: Changes in the antioxidant enzymes and glutathione levels in saliva from two different pathologic situations as those here studied suggest that this biologic fluid may be suitable for determining the prognosis and evolution of these diseases and its oral manifestations.     

高糖对人牙髓细胞增殖及氧化应激的影响

目的 探讨高糖对人牙髓细胞(HDPCs)增殖和氧化应激的影响,以探索高糖环境对牙髓的影响机制.方法 分离培养牙髓细胞,鉴定组织来源,实验分为4组:低糖组(葡萄糖5.5 mmol/L)、正常组(葡萄糖25 mmol/L)、高糖组(葡萄糖50mmol/L)、高渗组(与50 mmol/L组渗透压相等,并与5.5 mmol/L...     

谷氧还蛋白在牙龈卟啉单胞菌脂多糖诱导脐静脉内皮细胞氧化应激中的作用

目的 从基因和蛋白水平研究谷氧还蛋白（Grx）在牙龈卟啉单胞菌脂多糖（LPS）诱导脐静脉内皮细胞（EA-hy926细胞）时的表达变化及其对Akt通路的调控作用。方法 采用牙龈卟啉单胞菌的LPS（1 000 ng·mL^-1）对EA-hy926细胞进行不同时间段（4、12、18、24 h）的刺激诱导,采用实时荧光定量逆转录聚合酶链反应检测细胞grx1基因的表达变化;然后加入Grx特异性抑制剂氯化亚硝脲（BCNU）,使用Western blot法检测对照组、LPS组（1 000 ng·mL^-1LPS刺激12 h）和BCNU组（25 μmol·mL^-1BCNU预处理30 min+1 000 ng·mL^-1LPS刺激12 h）的Grx、Akt、磷酸化Akt蛋白的表达情况。结果 LPS诱导下,EA-hy926细胞的grx1基因表达量在各个时间段均上调,12 h时grx1表达量最高。LPS诱导12 h时,LPS组的Grx蛋白表达量较对照组明显升高（P<0.05）,而BCNU可有效抑制Grx蛋白的表达（P<0.05）;Akt蛋白表达量在各组间无明显差异（P>0.05）,而LPS组的磷酸化Akt活性升高,显著高于对照组和BCNU组（P<0.05）,与Grx蛋白的表达趋势一致。结论 LPS可以从基因和蛋白水平诱导Grx的表达;Grx是Akt的潜在调节因子,可能对LPS刺激下Akt的调控具有重要意义。