The Relationship between the Concentration of Salivary Tyrosine and Antioxidants in Patients with Oral Lichen Planus

Highly sensitive and simultaneous detection of ascorbic acid, dopamine, and uric acid using Pt@g-C3N4/N-CNTs nanocomposites

The detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is crucial for understanding and managing various illnesses. In this research, Pt@g-C3N4 nanoparticles were synthesized via hydrothermal method and combined with N-doped carbon nanotubes (N-CNTs). The Pt@g-C3N4/N-CNTs-modified glassy carbon (GC) electrode was fabricated as an electrochemical sensor for the determination of AA, DA, and UA. The linear response range of AA, DA, and UA in the optimal condition was 100-3,000 μM, 1-100 μM, and 2-215 μM boasting a low detection limit (S/N = 3) of 29.44 μM (AA), 0.21 μM (UA), and 2.99 μM (DA), respectively. Additionally, the recoveries of AA, DA, and UA in serum sample were 100.4%-106.7%. These results corroborate the feasibility of the proposed method for the simultaneous, sensitive, and reliable detection of AA, DA, and UA. Our Pt@g-C3N4/N-CNTs/GC electrode can provide a potential strategy for disease diagnosis and health monitoring in clinical settings.

ASCT2-mediated glutamine uptake promotes Th1 differentiation via ROS-EGR1-PAC1 pathway in oral lichen planus

Oral lichen planus (OLP) is a T cell-mediated autoimmune disease of oral mucosa concerning with the redox imbalance. Although glutamine uptake mediated by alanine-serine-cysteine transporter 2 (ASCT2) is critical to T cell differentiation, the exact mechanism remains ambiguous. Here, we elucidate a novel regulatory mechanism of ASCT2-mediated uptake in the differentiation and proliferation of T cells through maintaining redox balance in OLP. The results of immunohistochemistry (IHC) showed that both ASCT2 and glutaminase (GLS) were obviously upregulated compared to controls in OLP. Moreover, correlation analyses indicated that ASCT2 expression was significantly related to GLS level. Interestingly, the upregulation of glutamine metabolism in epithelial layer was consistent with that in lamina propria. Functional assays in vitro revealed the positive association between glutamine metabolism and lymphocytes infiltration. Additionally, multiplex immunohistochemistry (mIHC) uncovered a stronger colocalization among ASCT2 and CD4 and IFN-γ, which was further demonstrated by human Th1 differentiation assay in vitro. Mechanistically, targeting glutamine uptake through interference with ASCT2 using L-γ-Glutamyl-p-nitroanilide (GPNA) decreased the glutamine uptake of T cells and leaded to the accumulation of intracellular reactive oxygen species (ROS), which promoted dual specificity phosphatase 2 (DUSP2/PAC1) expression through activation of early growth response 1 (EGR1) to induce dephosphorylation of signal transducer and activator of transcription 3 (STAT3) and inhibit Th1 differentiation in turn. These results demonstrated that glutamine uptake mediated by ASCT2 induced Th1 differentiation by ROS-EGR1-PAC1 pathway, and restoring the redox dynamic balance through targeting ASCT2 may be a potential treatment for T cell-mediated autoimmune diseases.

Protein Intake and Oral Health in Older Adults-A Narrative Review

Oral health is vital to general health and well-being for all ages, and as with other chronic conditions, oral health problems increase with age. There is a bi-directional link between nutrition and oral health, in that nutrition affects the health of oral tissues and saliva, and the health of the mouth may affect the foods consumed. Evidence suggests that a healthy diet generally has a positive impact on oral health in older adults. Although studies examining the direct link between oral health and protein intake in older adults are limited, some have explored the relationship via malnutrition, which is also prevalent among older adults. Protein-energy malnutrition (PEM) may be associated with poor oral health, dental caries, enamel hypoplasia, and salivary gland atrophy. This narrative review presents the theoretical evidence on the impact of dietary protein and amino acid composition on oral health, and their combined impact on overall health in older adults.

Determination of up to twenty carboxylic acid containing compounds in clinically relevant matrices by o-benzylhydroxylamine derivatization and liquid chromatography-tandem mass spectrometry

Carboxylic acid containing compounds (R-COOH) are involved in a large number of biological processes and they are relevant for several pathological processes such as neurodegeneration or cancer. Comprehensive methodologies for the quantitative determination of R-COOH in biological samples are required. In this study we have developed a LC-MS/MS method for the quantification of 20 endogenous R-COOH belonging to different pathways such as kynurenine metabolism, serotoninergic pathway, glycolysis, tricarboxylic acid cycle, dopaminergic pathway, short chain fatty acids and glycine metabolism. The approach included derivatization with o-benzylhydroxylamine (reaction time 1 h), liquid-liquid extraction with ethyl acetate and LC-MS/MS detection (run time 10 min). The method was optimized and validated in 5 different matrices (urine, plasma, saliva, brain and liver) following two different approaches: (i) using surrogate matrices and (ii) using actual human samples by standard additions. A suitable linearity was obtained in the endogenous range of the analytes. Adequate intra and inter-assay accuracies (80-120%) and intra- and inter-assay precisions (<20%) were achieved for almost all analytes in all studied matrices. The method was applied in several scenarios to confirm (i) human urinary changes produced in glycolysis after exercise, (ii) metabolic changes produced in rat brain and plasma by methamphetamine administration and (iii) metabolic alterations in human plasma caused by vitamin B6 deficiency. Additionally, the application of the method allowed for establishing previously unreported alterations in R-COOH metabolites under these conditions. Due to the comprehensive analyte and matrix coverage and the wide applicability of the developed methodology, it can be considered as a suitable tool for the study of R-COOH status in health and disease by targeted metabolomics.

Salivary Uric Acid: A Noninvasive Wonder for Clinicians?

This review is a summary of the modern-day approach and recent trend in the determination of uric acid in the saliva of humans and its use in diagnosis by clinicians. Uric acid, which is the end product obtained from the breakdown of purine nucleotides, is an important biomarker associated with various conditions. Uric acid is found in various body fluids, such as serum, plasma, and urine. It can be used as an important tool for various diseases, such as gout and hyperuricemia, or conditions that are associated with increased oxidative stress. Recently, there has been an emergence of studies that have utilized uric acid concentrations measured in the saliva and studied its association with various diseases. Salivary uric acid can prove to be a noninvasive method to provide a diagnosis of serious illness. A raised uric acid level in the saliva can be associated with cancer, human immunodeficiency virus (HIV) infection, gout, and hypertension. A reduced level of salivary uric acid on the other hand can be a marker for Alzheimer's disease, progression of multiple sclerosis, and impairment of cognition. Online search databases, including Google Scholar, Scopus, PubMed, and Web of Science, were searched, and articles that were published before September 2021 based on salivary uric acid analysis were analyzed for this review. Uric acid is an essential biomarker that has antioxidant properties. Assessment of salivary uric acid levels was found to be essential in conditions such as cancer, metabolic syndrome, neurological conditions, psychiatric conditions, human immunodeficiency virus, and gout and in monitoring treatment of hyperuricemia. Although having importance in diagnosis and therapeutic monitoring, salivary uric acid analysis has not gained enough popularity due to limitations such as saliva collection and sample processing issues. With proper education and standardization, salivary uric acid analysis can be used as a cost-effective and noninvasive tool for getting a clue about antioxidant biomarker concentration in saliva and hence various diseases associated with oxidative stress.

Systematic Review and Meta-Analysis of Oxidative Stress and Antioxidant Markers in Oral Lichen Planus

Background

Oral lichen planus (OLP) is a relatively common chronic inflammatory disease of unknown etiology, which might be caused by oxidative stress and impaired antioxidant defense.

Objective

To systematically investigate the markers of oxidative stress and antioxidant systems in the saliva and blood from OLP patients and healthy controls.

Methods

The PubMed, Cochrane Library, and Embase were systematically queried to collect data from studies in which oxidative stress/antioxidant markers from OLP and healthy subjects had been evaluated until March 10, 2021.

Results

A total of 28 studies fulfilled inclusion criteria, and 25 of them, having 849 OLP patients and 1,052 control subjects and analyzing 12 oxidative stress and antioxidant state marker levels, were subjected to meta-analysis. We found a significant decrease in total antioxidant capacity (TAC) and uric acid (UA) and a significant increase in malondialdehyde (MDA) and nitric oxide (NO) levels in the saliva and serum/plasma of OLP patients. Moreover, a significant elevation of 8-hydroxy-deoxyguanosine (8-OHdG) and advanced oxidation protein product (AOOP) level and a decrease in vitamin C were also observed in the saliva of the OLP group. In contrast, salivary vitamin A, zinc, glutathione peroxidase (GPx), vitamin E, and nitrite were not significantly different between the two groups. In single studies, markers of oxidative stresses such as superoxide dismutase (SOD) and 8-isoprostanelevels were elevated in OLP, and antioxidant parameters such as glutathione (GSH) and total protein (TP) levels were dysregulated.

Conclusion

This meta-analysis helps to clarify the profile of oxidative stress and antioxidant state markers in OLP patients although existing evidence is rather heterogeneous and many studies are affected by several limitations. Larger and more standardized studies are warranted to ascertain whether these markers are potential causes or effects of OLP and whether antioxidant therapy improving oxidative stress will be useful.

Enhanced Salivary and General Oxidative Stress in Hashimoto's Thyroiditis Women in Euthyreosis

Hashimoto’s thyroiditis (HT) is one of the most common autoimmune diseases. Although HT is inextricably linked to oxidative stress, there have been no studies assessing salivary redox homeostasis or salivary gland function in patients with HT. This study is the first to compare antioxidant defense and oxidative stress biomarkers in non-stimulated (NWS) and stimulated (SWS) whole saliva and plasma/erythrocytes of HT patients compared to controls. The study included 45 women with HT in the euthyreosis period as well as an age- and gender-matched control group. We showed that NWS secretion was significantly lower in HT patients compared to healthy controls, similar to salivary amylase activity in NWS and SWS. Catalase and peroxidase activities were considerably higher in NWS and SWS of HT patients, while the concentrations of reduced glutathione and uric acid were significantly lower in comparison with healthy subjects. Total antioxidant potential was significantly lower, while total oxidant status and the level of oxidation products of proteins (advanced glycation end products, advanced oxidation protein products) and lipids (malondialdehyde, lipid hydroperoxides) were significantly higher in NWS, SWS and plasma of HT patients. In conclusion, in both salivary glands of women with HT in euthyreosis, the ability to maintain redox homeostasis was hindered. In HT patients we observed oxidative damage to salivary proteins and lipids; thus, some biomarkers of oxidative stress may present a potential diagnostic value.