Enhanced Cardiovascular Risk and Altered Oxidative Status in Elders with Moderate Excessive Body Fat

The Relationship Between Salivary Redox, Diet, and Food Flavor Perception

The mouth is the gateway for entrance of food and microorganisms into the organism. The oral cavity is bathed by saliva, which is thus the first fluid that food and microorganisms will face after their entrance. As a result, saliva plays different functions, including lubrication, predigestion, protection, detoxification, and even transport of taste compounds to chemoreceptors located in the taste buds. To ensure its function of protection, saliva contains reactive harmful compounds such as reactive oxygen species that are controlled and neutralized by the antioxidant activity of saliva. Several antioxidant molecules control the production of molecules such as reactive oxygen compounds, neutralize them and/or repair the damage they have caused. Therefore, a balance between reactive oxidant species and antioxidant compounds exists. At the same time, food can also contain antioxidant compounds, which can participate in the equilibrium of this balance. Numerous studies have investigated the effects of different food components on the antioxidant capacity of saliva that correspond to the ability of saliva to neutralize reactive oxygen species. Contradictory results have sometimes been obtained. Moreover, some antioxidant compounds are also cofactors of enzymatic reactions that affect flavor compounds. Recent studies have considered the salivary antioxidant capacity to explain the release of flavor compounds ex vivo or in vivo. This article aims to review the effect of food on the antioxidant capacity of saliva and the impact of salivary antioxidant capacity on flavor perception after a brief presentation of the different molecules involved.

Dysfunction of Salivary Glands, Disturbances in Salivary Antioxidants and Increased Oxidative Damage in Saliva of Overweight and Obese Adolescents

Obesity is inseparably connected with oxidative stress. This process may disturb the functioning of the oral cavity, although the effect of oxidative stress on salivary gland function and changes in the qualitative composition of saliva are still unknown. Our study is the first to evaluate salivary redox homeostasis in 40 overweight and obese adolescents and in the age- and gender-matched control group. We demonstrated strengthening of the antioxidant barrier (superoxide dismutase, catalase, peroxidase, uric acid, total antioxidant capacity (TAC)) with a simultaneous decrease in reduced glutathione concentration in saliva (non-stimulated/stimulated) in overweight and obese teenagers compared to the controls. The concentration of the products of oxidative damage to proteins (advanced glycation end products), lipids (malondialdehyde, 4-hydroxynonenal) and DNA (8-hydroxydeoxyguanosine) as well as total oxidative status were significantly higher in both non-stimulated and stimulated saliva as well as plasma of overweight and obese adolescents. Importantly, we observed more severe salivary and plasma redox alterations in obese adolescents compared to overweight individuals. In the study group, we also noted a drop in stimulated salivary secretion and a decrease in total protein content. Interestingly, dysfunction of parotid glands in overweight and obese teenagers intensified with the increase of BMI. We also showed that the measurement of salivary catalase and TAC could be used to assess the central antioxidant status of overweight and obese adolescents.

High-Fat Diet Affects Ceramide Content, Disturbs Mitochondrial Redox Balance, and Induces Apoptosis in the Submandibular Glands of Mice

This is the first study to investigate the relationship between ceramides, the mitochondrial respiratory system, oxidative stress, inflammation, and apoptosis in the submandibular gland mitochondria of mice with insulin resistance (IR). The experiment was conducted on 20 male C57BL/6 mice divided into two equal groups: animals fed a high-fat diet (HFD; 60 kcal% fat) and animals fed a standard diet (10 kcal% fat). We have shown that feeding mice HFD induces systemic IR. We noticed that HFD feeding was accompanied by a significant increase in ceramide production (C18 1Cer, C18 Cer, C22 Cer, C24 1Cer, C24 Cer), higher activity of pro-oxidant enzymes (NADPH oxidase and xanthine oxidase), and weakened functioning of mitochondrial complexes in the submandibular glands of IR mice. In this group, we also observed a decrease in catalase and peroxidase activities, glutathione concentration, redox status, increased concentration of protein (advanced glycation end products, advanced oxidation protein products) and lipid (malondialdehyde, lipid hydroperoxide) peroxidation products, and enhanced production of tumor necrosis factor alpha (TNFα) and interleukin 2 (IL-2) as well as pro-apoptotic Bax in the submandibular gland mitochondria. In summary, HFD impairs salivary redox homeostasis and is responsible for enhanced oxidative damage and apoptosis in the submandibular gland mitochondria. The accumulation of some ceramides could boost free radical formation by affecting pro-oxidant enzymes and the mitochondrial respiratory chain.

Salivary and plasma native and non-urate total antioxidant capacity versus oral health status in older non-smoking adults

OBJECTIVE

The aim of this study was to evaluate the salivary C-reactive protein and native and non-urate total antioxidant capacity (TAC) of saliva and plasma in relation to various oral health status indexes in older non-smoking adults.

DESIGN

Oral health status indices involved the Decayed, Missing, Filled Teeth index, the number of decayed teeth, Approximal Plaque Index, Plaque Index and Community Periodontal Index with Treatment Needs. Sixty older patients (67.0 ± 4.5 years) with different levels of oral health were examined. Salivary C-reactive protein was assessed. The Ferric Reducing Ability of Saliva/Plasma (FRAS/FRAP) and 2.2-diphenyl-1-picryl-hydrazyl test of saliva/plasma (DPPHS/DPPH) were used to assess the native and non-urate salivary (FRAS, non-urate FRAS, DPPHS, non-urate DPPHS, and plasma TAC (FRAP, non-urate FRAP, DPPH, non-urate DPPH).

RESULTS

Salivary C-reactive protein, native TAC and non-urate TAC did not correspond to any oral health status index. No relation was found for plasma native and non-urate TAC either. In multivariate analyses, age was the only independent predictor of DPPHS and salivary uric acid (p < 0.05) while non-urate DPPH was only negatively predicted by Body Mass Index (p < 0.001). None of oral health status indices was selected as an independent predictor of salivary and plasma TAC or C-reactive protein of saliva.

CONCLUSION

Oral health status indexes did not appear to influence the native or the non-urate local antioxidant status of saliva, or the systemic antioxidant status of plasma; they had no local effect related to salivary C-reactive protein. However, lower plasma non-urate antioxidant potential was related to overweight/obesity.

Oxidative stress biomarkers in the serum and plasma of patients with non-alcoholic fatty liver disease (NAFLD). Can plasma AGE be a marker of NAFLD? Oxidative stress biomarkers in NAFLD patients

Still little is known about the redox abnormalities in patients with non-alcoholic fatty liver disease (NAFLD). The purpose of the study was to find the relationship between enzymatic and non-enzymatic antioxidants, redox homeostasis and oxidative damage in 67-patients with NAFLD. The study population was divided into patients with non-alcoholic fatty liver (early NAFLD, n = 29) and patients with non-alcoholic steatohepatitis (advanced NAFLD, n = 38). Redox biomarkers: enzymatic antioxidants (Cu - Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR)); non-enzymatic antioxidants and redox status (reduced glutathione (GSH), total antioxidant capacity (TAC)); and oxidative damage products (total oxidant status (TOS), advanced glycation end products (AGE), malondialdehyde (MDA), and DNA/RNA oxidative damage) were determined in the serum/plasma samples. The activity of SOD, GPx, GR and levels of GSH, TOS, AGE, MDA, and DNA/RNA oxidative damage were significantly elevated in early NAFLD and advanced NAFLD group compared to controls (p < .001). There was a positive correlation between AGE, TAC and ALT activity (R = 0.34, p = .04; R = 0.36, p = .03, respectively) in advanced NAFLD group. Interestingly, ROC analysis for AGE showed good discriminatory ratio for patients with minimal steatosis (BARD score 0-1) vs. moderate steatosis (BARD score 2-4), AUC = 0.76. Plasma AGE can be a potential non-invasive biomarker differentiating NAFLD patients.

Effect of N-Acetylcysteine on Antioxidant Defense, Oxidative Modification, and Salivary Gland Function in a Rat Model of Insulin Resistance

Oxidative stress plays a crucial role in the salivary gland dysfunction in insulin resistance (IR). It is not surprising that new substances are constantly being sought that will protect against the harmful effects of IR in the oral cavity environment. The purpose of this study was to evaluate the effect of N-acetylcysteine (NAC) on oxidative stress and secretory function of salivary glands in a rat model of insulin resistance. Rats were divided into 4 groups: C-normal diet, C + NAC-normal diet + NAC, HFD-high-fat diet, and HFD + NAC. We have demonstrated that NAC elevated enzymatic (superoxide dismutase, catalase, and peroxidase) and nonenzymatic antioxidants (reduced glutathione (GSH) and total antioxidant capacity (TAS)) in the parotid glands of HFD + NAC rats, while in the submandibular glands increased only GSH and TAS levels. NAC protects against oxidative damage only in the parotid glands and increased stimulated salivary secretion; however, it does not increase the protein secretion in the both salivary glands. Summarizing, NAC supplementation prevents the decrease of stimulated saliva secretion, seen in the HFD rats affected. NAC improves the antioxidative capacity of the both glands and protects against oxidative damage to the parotid glands of IR rats.

Oxidative Modification in the Salivary Glands of High Fat-Diet Induced Insulin Resistant Rats

Still little is known about the role of oxidative stress (OS) in the pathogenesis of the salivary gland dysfunction in the course of insulin resistance (IR). To induce IR rats was fed with a high fat diet (HFD) during 8 weeks. Stimulated and non-stimulated salivary flow rate, total protein, as well as oxidative damage markers: 4-HNE protein adduct, 8-isoprostanes (8-isoP), 8-hydroxy-D-guanosine (8-OHdG), advanced oxidation protein product (AOPP), and protein carbonyls (PC) were determined in the plasma and submandibular and parotid glands of IR and control rats. We have shown a significant decrease (45%) of the stimulated salivary flow rate, and in the total protein concentration in the parotid (35%) and submandibular (10%) glands of HFD IR as compared to the control rats. The level of 4-HNE protein adduct (15%) and 8-isoP (20%) in the submandibular glands of IR rats as well as total level of 4-HNE protein adduct (39%), 8-isoP (27%), AOPP (25%), PC (32%), and 8-OHdG (18%) in the parotid glands of IR rats were significantly higher as compared to the control group. We showed no correlation between the assessed OS parameters in the plasma and salivary glands. However, the redox balance in both glands shifted toward the oxidative status, parotid glands of IR rats are exposed to greater intensity OS. Stimulated secretory ability and mechanisms involved in the synthesis/secretion of proteins in the salivary glands are depressed in the course of IR. Oxidative damage in the salivary glands arises independently from the general OS in the course of insulin resistance induced by a high fat diet.

Peripheral brain-derived neurotrophic factor is related to cardiovascular risk factors in active and inactive elderly men

Regular exercise plays an important preventive and therapeutic role in heart and vascular diseases, and beneficially affects brain function. In blood, the effects of exercise appear to be very complex and could include protection of vascular endothelial cells via neurotrophic factors and decreased oxidative stress. The purpose of this study was to identify the age-related changes in peripheral brain-derived neurotrophic factor (BDNF) and its relationship to oxidative damage and conventional cardiovascular disease (CVD) biomarkers, such as atherogenic index, C-reactive protein (hsCRP) and oxidized LDL (oxLDL), in active and inactive men. Seventeen elderly males (61-80 years) and 17 young males (20-24 years) participated in this study. According to the 6-min Åstrand-Rhyming bike test, the subjects were classified into active and inactive groups. The young and elderly active men had a significantly better lipoprotein profile and antioxidant status, as well as reduced oxidative damage and inflammatory state. The active young and elderly men had significantly higher plasma BDNF levels compared to their inactive peers. BDNF was correlated with VO2max (r=0.765, P<0.001). In addition, we observed a significant inverse correlation of BDNF with atherogenic index (TC/HDL), hsCRP and oxLDL. The findings demonstrate that a high level of cardiorespiratory fitness reflected in VO2max was associated with a higher level of circulating BDNF, which in turn was related to common CVD risk factors and oxidative damage markers in young and elderly men.

Impact of morbid obesity and bariatric surgery on antioxidant/oxidant balance of the unstimulated and stimulated human saliva

OBJECTIVE

There is no study evaluating the influence of morbid obesity and bariatric surgery on antioxidant/oxidant homeostasis of the unstimulated and stimulated human saliva.

MATERIALS AND METHODS

Salivary flow rate, total antioxidant status (TAS), total oxidant status (TOS), oxidative status index (OSI), the total amount of uric acid (UA), polyphenols (pPh), catalase (CAT), superoxide dismutase 2 (SOD2), specific activity of peroxidase (Px), as well as malondialdehyde (MDA), and advanced glycation end products (AGE) concentrations were determined in the unstimulated (UWS) and stimulated (SWS) whole saliva of patients with morbid obesity before and after bariatric surgery.

RESULTS

In both UWS and SWS, the total amount of TOS, OSI, SOD2, and MDA was statistically higher in patients with morbid obesity as compared to the healthy controls, as well as significantly lower in the patients treated surgically as compared to the obese patients. The median values of the total amount of TAS, CAT, UA, pPh, and specific activity of Px were significantly reduced in UWS and SWS in patients with morbid obesity as compared to the control group and also statistically elevated in patients after bariatric surgery as compared to the patients with morbid obesity.

CONCLUSIONS

In morbid obesity, reduced unstimulated and stimulated salivary flow can be observed. Bariatric surgery restored only unstimulated salivary flow to normal values. Disturbances in oxidant/antioxidant homeostasis may be observed in UWS and SWS of obese patients before and after treatment.