Nitrative and oxidative DNA damage in oral lichen planus in relation to human oral carcinogenesis

Salivary metabolomics in patients with oral lichen planus: a preliminary study based on NMR spectroscopy

OBJECTIVES

The present preliminary study aimed to investigate the salivary metabolic profile in patients with asymptomatic oral lichen planus (OLP) using nuclear magnetic resonance (NMR) spectroscopy.

MATERIAL AND METHODS

Stimulated whole mouth saliva (SWMS) samples were collected from 15 reticular OLP female patients and 15 from age- and sex-matched controls (HCs). A total of 23 metabolites were identified and quantified. Mann-Whitney's U test was used to compare the determined concentration salivary metabolite concentrations between OLP patients and the healthy controls.

RESULTS

The concentration of acetate, methylamine, and pyruvate was elevated, whereas the concentration of tyrosine was decreased in the saliva of OLP patients compared with HCs. To identify a combination of metabolites, multivariate discrimination function analysis (DFA) was conducted. DFA analysis have shown that the most powerful discrimination between the groups was achieved when methylamine and tyrosine were considered as combined biomarkers.

CONCLUSIONS

Salivary tyrosine was of particular interest and a promising finding for the screening of OLP and its progression. Further longitudinal studies are required to establish it as a reliable salivary biomarker in OLP.

CLINICAL RELEVANCE

The salivary metabolic profiling can describe the pathologic characteristics of OLP on non-invasive saliva samples and NMR analysis. Salivary metabolites provide details to considered early detectors and to impact oral health of OLP patients.

Narrow-band imaging features of oral lichenoid conditions: A multicentre retrospective study

OBJECTIVE

Narrow-band imaging (NBI), which highlights epithelial intrapapillary capillary loops (IPCLs) classified into five patterns (0 toIV) with increasing correlation to malignancy, has demonstrated effectiveness for detection of oral squamous cell carcinoma (OSCC). Lack of standardised procedures limits its use for routine inspection of oral lichenoid lesions including oral lichen planus (OLP), oral lichenoid lesion (OLL) and oral lichenoid reaction (OLR). The aim of this study was to analyse IPCL patterns of such lesions, assessing correlations with histopathological outcomes.

MATERIALS AND METHODS

A multicentre, retrospective study was performed on 84 patients who underwent NBI and subsequent biopsy for suspected OLP/OLL/OLR. Patients were examined with Evis Exera III NBI system. Recorded NBI video endoscopies were evaluated to assess IPCL patterns and correlated with histopathological outcomes.

RESULTS

No significant differences were detected among OLP/OLL/OLR on NBI inspection. All lichenoid lesions were significantly related to low-grade (0-II) IPCL patterns, clearly distinguishable from OSCC, showing pattern IV (p < 0.05).

CONCLUSIONS

NBI cannot discern among OLP/OLL/OLR lesions. Interpretation should be modulated when assessing lichenoid lesions. NBI has potential to discern malignant transformation occurring in lichenoid lesions undergoing long-term follow-up, as IPCL pattern IV may be used as a clinical marker of malignancy arising in chronic inflammatory lesions.

The Effect of Local Melatonin Application Following the Removal of an Impacted Mandibular Third Molar

PURPOSE

Pain, swelling, limitation of the mouth opening, development of intra-bony defects, and bone loss are common side effects of removing the impacted third molar. The purpose of this study was to measure the association of applying melatonin in the socket of an impacted mandibular third molar with osteogenic activity and the anti-inflammatory effects.

METHODS

This prospective, randomized, blinded trial comprised of patients who required removal of the impacted mandibular third molar. The patients were divided into two groups (n = 19) as follows: melatonin group (3 mg of melatonin into 2 ml of 2% hydroxyethyl cellulose gel was packed into the socket) and placebo group (2 ml of 2% hydroxyethyl cellulose gel was placed in the socket). The primary outcome was bone density, measured using Hounsfield unit immediately after surgery and 6 months later. Secondary outcome variables included serum osteoprotegerin level (Ng/ml) that measured immediately, 4 weeks and 6 months postoperatively. Other clinical outcome measures were pain by visual analog scale, maximum mouth opening (MMO) (millimeter), and swelling (millimeter) that were evaluated immediately, 1, 3, and 7 days postoperatively. The data were analyzed by independent t-test of Wilcoxon's rank-sum, analysis of variance, and generalized estimating equation (P ≤ .05).

RESULTS

Thirty-eight patients (25 female and 13 males) with a median age of 27 years were enrolled in the study. There was no statistical significance in bone density observed in both groups [melatonin group: 978.5(951.3-1015.8), control group: 965.8 (924.6-998.7), P = .1]. Alternatively, there were statistically significant improvements in osteoprotegerin levels (on week 4), MMO (on day1), and swelling (on day 3) in the melatonin group compared to those in the placebo group [1.9(1.4-2.4), 39.68 ± 1.35, and 14.36 ± 0.80 versus 1.5(1.2-1.4); 38.33 ± 1.20, and 14.88 ± 0.59; P = .02, .003, 0.031, respectively]. The pain values showed statistically significant improvement throughout the follow-up period in the melatonin group compared to the placebo group [5(3-8), 2(1-5), and 0(0-2) versus 7(6-8), 5(4-6), and 2(1-3); P < .001, respectively].

CONCLUSIONS

The results support the anti-inflammatory effect of melatonin in reducing the pain scale and swelling. Furthermore, it plays a role in the improvement of MMO. On the other hand, the osteogenic activity of melatonin could not be detected.

Oral lichen planus identification by mid-infrared spectroscopy of oral biofluids: A case-control study

BACKGROUND AND AIMS

This study aims to access the effectiveness of mid-infrared (MIR) spectroscopy on the identification of the reticular form of OLP, following the assessment of gingival crevicular fluid (GCF) and oral mucosa transudate (OMT).

MATERIAL AND METHODS

The trial follows a case-control design. Samples were characterized through MIR spectroscopy and chemometric tools were applied to distinguish between case and control participants, further identifying the spectral regions with the highest contribution to the developed models.

RESULTS

MIR spectroscopy was capable to discriminate between OLP patients and controls with 95.1% and 85.4% of correct predictions, regarding GCF and OMT samples, respectively. Additionally, the spectral regions mostly contributing to the successful prediction were identified, and possibly related with the distinctive presence of amino acids/proteins and oxidative stress mediators in oral biofluids, supporting the role of the immune-inflammatory activation on OLP etiology and disease course.

CONCLUSION

MIR spectroscopy analysis of GCF and OMT may be regarded as an innovative, non-invasive, low cost and sensitive technique, contributing to the identification of the reticular from of OLP.

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.

Effect of Lactobacillus fermentum HFY03 on the Antifatigue and Antioxidation Ability of Running Exhausted Mice

Yak yogurt is mainly produced in Qinghai-Tibet Plateau. It is a kind of naturally fermented dairy product. It contains abundant microorganisms. Lactobacillus fermentum (LF) HFY03 is a lactic acid bacteria derived from it. Our main research content is to study the influence of LF-HFY03 on the antifatigue and antioxidation ability of running exhausted mice. We gave different doses of LF-HFY03 to mice by gavage for 4 weeks. We selected vitamin C as the positive control group, mainly to study the relationship between antioxidant capacity and fatigue resistance and LF-HFY03 in mice with running exhaustion. The results showed that LF-HFY03 and vitamin C could significantly improve the running time of mice. And with the increase in LF-HFY03 concentration, the exhaustion time of mice was also extended. LF-HFY03 can reduce the content of urea nitrogen and lactic acid and also can increase the content of free fatty acids and liver glycogen. The levels of alanine aminotransferase, serum creatine kinase, and aspartate aminotransferase in mice decreased gradually as the antioxidant peptide level of walnut albumin increased. LF-HFY03 can reduce malondialdehyde (MDA) levels in a quantification-dependent manner and can also increase catalase (CAT) and superoxide dismutase (SOD) levels. LF-HFY03 can also increase the expressions of CAT mRNA, Cu/Zn-SOD, and Mn-SOD in the liver of mice. At the same time, LF-HFY03 can also increase the expression of protein of threonine transporter 1 (AST1)/alanine/cysteine/serine, mRNA, nNOS, and eNOS. At the same time, the solution could reduce the expression of TNF-α, syncytin-1, and inducible nitric oxide synthase (iNOS). The results showed that LF-HFY03 has a high development and application prospect as an antifatigue probiotic nutritional supplement.

Effect of TTLL12 on tubulin tyrosine nitration as a novel target for screening anticancer drugs in vitro

Nitrotyrosine, a structural analogue of tyrosine, is present in cells in pathological conditions and is incorporated into tubulin to form tubulin tyrosine nitration, which disrupts the normal function of microtubules. There is limited research on the functional aspects of tubulin tyrosine nitration in different types of tumor. In the present study, the effect of tubulin tyrosine nitration and tubulin tyrosine ligase like 12 (TTLL12) on the proliferation of SCC-25 cells was investigated. TTLL12-overexpressing cell lines were constructed and used to assess the effect of tubulin tyrosine nitration and TTLL12 on the proliferation of SCC-25 cells via western blotting, immunofluorescent and MTT assays. An TTLL12-stably overexpressing SCC-25 cell line and the enzyme-linked immunosorbent assay were used to establish a novel experiment in vitro for screening anticancer drugs targeting tubulin tyrosine nitration by assessing its sensitivity, specificity and repeatability, and using it to find an effective drug. The results demonstrated that the proliferative rate of the control cells was notably inhibited in the presence of nitrotyrosine compared with that of TTLL12-overexpressing cells. The results of the MTT assay revealed that the proliferation of TTLL12-silenced cells was significantly inhibited compared with that of the control group. The sensitivity, specificity and repeatability of the experiment were positive. It was found that nocodazole could have better anticancer effect than paclitaxel. Taken together, the results of the present study suggest that TTLL12 enhances SCC-25 cell survival in the presence of nitrotyrosine by disrupting nitration of the tyrosine residues of tubulin, and tubulin tyrosine nitration may be developed for the basic research of anticancer drugs.

Wine Consumption and Oral Cavity Cancer: Friend or Foe, Two Faces of Janus

The health benefits of moderate wine consumption have been extensively studied during the last few decades. Some studies have demonstrated protective associations between moderate drinking and several diseases including oral cavity cancer (OCC). However, due to the various adverse effects related to ethanol content, the recommendation of moderate wine consumption has been controversial. The polyphenolic components of wine contribute to its beneficial effects with different biological pathways, including antioxidant, lipid regulating and anti-inflammatory effects. On the other hand, in the oral cavity, ethanol is oxidized to form acetaldehyde, a metabolite with genotoxic properties. This review is a critical compilation of both the beneficial and the detrimental effects of wine consumption on OCC.

Oxidative stress, neutrophil elastase and IGFBP7 levels in patients with oropharyngeal cancer and chronic periodontitis

OBJECTIVE

The present study focused on investigating levels of oxidative stress, neutrophil elastase (NE), and insulin-like growth factor-binding protein 7 (IGFBP7) in oropharyngeal cancers (OC) with the presence and absence of periodontitis.

MATERIALS AND METHODS

A healthy non-periodontitis group (H-NP; n = 20), a systemically healthy chronic periodontitis group (H-P; n = 20), a non-periodontitis group with OC (OC-NP; n = 12), and a chronic periodontitis group with OC (OC-P; n = 16) formed the study groups. The levels of NE and IGFBP7 were measured in gingival crevicular fluid (GCF) and saliva. In addition, oxidative status was determined by evaluating total oxidant status (TOS), total antioxidant status (TAS), and OSI (TOS/TAS).

RESULTS

Gingival crevicular fluid NE was higher in all the groups compared with the H-NP group (p < .01). Salivary NE was higher in the OC-P and H-P groups compared with the H-NP and OC-NP groups (p < .05). Salivary IGFBP7 was significantly higher in the OC-NP and OC-P groups compared with the H-NP and H-P groups (p < .001). GCF TOS and OSI levels were significantly higher in all groups compared with the H-NP group (p < .05).

CONCLUSIONS

Gingival crevicular fluid NE levels were lower in healthy conditions compared with periodontal disease and OC. Salivary NE levels were higher in periodontal disease compared to states with no periodontal disease. Salivary IGFBP7 levels were higher in OC. Further analyses may help determine whether high salivary IGFBP7 levels distinguish OC from healthy conditions.

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

The diagnosis of oral lichen planus (OLP) is based on clinical examination and histopathological criteria. Noninvasive diagnostics of saliva may be considered as a confirmation of OLP diagnosis and a potential alternative to an invasive method. The objective of the present study was to evaluate the relationship between the level of tyrosine (Tyr) as well as antioxidants like uric acid (UA) and glutathione peroxidase (GPx) activity in the saliva of patients with OLP in comparison with the control group (healthy subjects without any oral changes). A total of 40 patients with OLP and 40 healthy volunteers were selected for the study based on the modified WHO diagnostic (clinical and histopathological) criteria. High-performance liquid chromatography (HPLC) was performed for Tyr concentration, while GPx activity and uric acid levels were determined by a colorimetric method. The concentrations of Tyr, UA, and GPx activity were statistically lowered in OLP patients compared to the control group. All examined parameters correlated strongly and positively with each other. Mean values of salivary UA concentrations differed between the groups of OLP patients (reticular and erosive forms) and controls (206.66 vs. 196.54 vs. 218.49 μmol/L, respectively, p = 0.001). A similar trend was demonstrated in salivary Tyr concentration which differed statistically between the study and control groups (0.08 vs. 0.07 vs. 0.13 μmol/L, respectively, p = 0.001). Determining of a relationship between the concentrations of Tyr, UA, and GPx activity may be useful in the prognosis of OLP. The HPLC method may be employed, as an additional noninvasive diagnostic procedure to screen OLP patients, during the routine diagnostics of salivary biochemical parameters such as aromatic amino acids.

Intraoral Ultra-High Frequency Ultrasound study of oral lichen planus: A pictorial review

BACKGROUND

Ultra-High Frequency Ultrasound (UHFUS) is a recently introduced diagnostic technique involving the use of higher frequencies compared to conventional ultrasound. Among the several fields of application, intraoral usage of UHFUS appears still limited. We report the intraoral evaluation of Oral Lichen Planus (OLP) by means of UHFUS and describe typical UHFUS aspect of different forms of presentation of OLP.

MATERIALS AND METHODS

Patients with clinical and histological diagnosis of OLP were enrolled in the study. OLP lesions were evaluated by means of intraoral UHFUS performed at 70 MHz, using B-mode and C-mode, in order to characterize the echostructure of each form of presentation.

RESULTS

Fifty patients in total were enrolled, and UHFUS features were described for different OLP forms. All the lesions showed a thick, hypoechoic superficial layer in the mucosal stratum, suggesting that such UHFUS alteration can be pathognomonic of OLP.

CONCLUSION

Ultra-High Frequency Ultrasound was able to differentiate superficial alterations of the oral mucosa, giving insight on possible applications of UHFUS in the study of OLP beyond clinical and histological investigations. Due to a limited study sample, we cannot draw firm conclusions. However, it is reasonable to think that UHFUS evaluation of OLP may provide useful information to the clinician.

Anti-inflammatory and antiresorptive functions of melatonin on experimentally induced periapical lesions

AIM

To investigate the effects of systemically administered melatonin on inflammation and alveolar bone resorption in rats with experimentally induced periapical lesions.

METHODOLOGY

Thirty adult Sprague Dawley rats were divided equally into negative, positive control and melatonin groups. The pulp chambers of their mandibular first molars were exposed to the oral environment to induce experimental periapical lesions in the positive control and melatonin groups. The melatonin group received daily intraperitoneal injections of melatonin at a dose of 10 mg kg^-1 . After 21 days, the animals were euthanized; the hemi-mandible parts were prepared for radiological, histopathological, immunohistochemical (IL-1β, RANK, RANKL, OPG and tartrate-resistant acid phosphatase (TRAP) and Brown-Brenn (bacteria) evaluations. Data were analysed by Kruskal-Wallis (for non-parametric data) and one-way anova tests (for parametric data) (P < 0.05).

RESULTS

The area of radiographic periapical bone loss was significantly smaller in rats that were given daily intraperitoneal injections of melatonin (P < 0.01). The histopathological scores of the melatonin group were significantly lower than those of positive control group (P < 0.01). Histomorphometrically, the area of periapical bone loss in the melatonin group was significantly smaller than the positive control group (P < 0.01). The expression of IL1-β, RANK and RANKL was significantly higher in the positive control group, whereas OPG was significantly higher in the melatonin group (P < 0.01). The number of osteoclasts was significantly greater in the positive control group by TRAP staining analyses (P < 0.01). The scores for bacteria localization using Brown-Brenn staining in the melatonin group was significantly lower than that of the positive control group (P < 0.01).

CONCLUSIONS

Melatonin demonstrated antiresorptive effects on bone associated with experimentally induced periapical lesions in rats via its anti-inflammatory activity. Further studies are necessary to evaluate its possible effects on the healing of periapical lesions.

Lichen planus of lip - Report of a rare case with review of literature

Lichen planus (LP) is a potentially malignant disorder with an immune-mediated etiopathogenesis. The condition frequently affects the skin, oral mucosa, skin appendages, and other mucous membranes. Oral lesions usually precede the onset of skin lesions and in majority of cases may only be presenting symptom. Isolated LP of the lip is rarely encountered in the clinical practice and is usually seen along with skin/other mucous membrane involvement. The clinical appearance poses diagnostic dilemmas and is often misinterpreted. This case report aims to highlight an interesting case of LP of the lower lip in a 50-year-old male patient. The patient presented with a diffuse erosive lesion on the lower lip bordered by white radiating striae on its inner aspect. Histopathological and immunofluorescent studies confirmed LP of the lip. Topical corticosteroids and Vaseline lip therapy were prescribed to the patient. There was considerable healing in the lip lesion during the follow-up period. However, recurrence was noted in the left buccal mucosa.

Crosstalk between DNA Damage and Inflammation in the Multiple Steps of Carcinogenesis

Inflammation can be induced by chronic infection, inflammatory diseases and physicochemical factors. Chronic inflammation is estimated to contribute to approximately 25% of human cancers. Under inflammatory conditions, inflammatory and epithelial cells release reactive oxygen (ROS) and nitrogen species (RNS), which are capable of causing DNA damage, including the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-nitroguanine. We reported that 8-nitroguanine was clearly formed at the sites of cancer induced by infectious agents including Helicobacter pylori, inflammatory diseases including Barrett's esophagus, and physicochemical factors including asbestos. DNA damage can lead to mutations and genomic instability if not properly repaired. Moreover, DNA damage response can also induce high mobility group box 1-generating inflammatory microenvironment, which is characterized by hypoxia. Hypoxia induces hypoxia-inducible factor and inducible nitric oxide synthase (iNOS), which increases the levels of intracellular RNS and ROS, resulting DNA damage in progression with poor prognosis. Furthermore, tumor-producing inflammation can induce nuclear factor-κB, resulting in iNOS-dependent DNA damage. Therefore, crosstalk between DNA damage and inflammation may play important roles in cancer development. A proposed mechanism for the crosstalk may explain why aspirin decreases the long-term risk of cancer mortality.

Expression of small leucine-rich extracellular matrix proteoglycans biglycan and lumican reveals oral lichen planus malignant potential

OBJECTIVES

The aim of this study was to examine molecular alterations on the protein level in lesions of oral lichen planus (OLP), oral squamous cell carcinoma (OSCC) and healthy mucosa.

MATERIALS AND METHODS

Global protein profiling methods based on liquid chromatography coupled to mass spectrometry (LC-MS) were used, with a special emphasis on evaluation of deregulated extracellular matrix molecules expression, as well as on analyses of IG2F and IGFR2 expression in healthy mucosa, OLP and OSCC tissues by comparative semi-quantitative immunohistochemistry.

RESULTS

Mass spectrometry-based proteomics profiling of healthy mucosa, OLP and OSCC tissues (and accompanied histologically unaltered tissues, respectively) identified 55 extracellular matrix proteins. Twenty among identified proteins were common to all groups of samples. Expression of small leucine-rich extracellular matrix proteoglycans lumican and biglycan was found both in OSCC and OLP and they were validated by Western blot analysis as putative biomarkers. A significant increase (p < 0.05) of biglycan expression in OLP-AT group was determined in comparison with OLP-T group, while lumican showed significant up-regulation (p < 0.05) in OLP-T and OSCC-T groups vs. adjacent and control tissue groups. Biglycan expression was only determined in OSCC-AT group. Immunohistochemical analysis of IGF2 and IG2FR expression revealed no significant difference among groups of samples.

CONCLUSION/CLINICAL RELEVANCE

Biglycan and lumican were identified as important pathogenesis biomarkers of OLP that point to its malignant potential.

Melatonin: A Review of Its Potential Functions and Effects on Dental Diseases

Melatonin is a hormone synthesised and secreted by the pineal gland and other organs. Its secretion, controlled by an endogenous circadian cycle, has been proven to exert immunological, anti-oxidant, and anti-inflammatory effects that can be beneficial in the treatment of certain dental diseases. This article is aimed at carrying out a review of the literature published about the use of melatonin in the dental field and summarising its potential effects. In this review article, an extensive search in different databases of scientific journals was performed with the objective of summarising all of the information published on melatonin use in dental diseases, focussing on periodontal diseases and dental implantology. Melatonin released in a natural way into the saliva, or added as an external treatment, may have important implications for dental disorders, such as periodontal disease, as well as in the osseointegration of dental implants, due to its anti-inflammatory and osseoconductive effects. Melatonin has demonstrated to have beneficial effects on dental pathologies, although further research is needed to understand the exact mechanisms of this molecule.

Malignant transformation of oral lichen planus and oral lichenoid lesions: A meta-analysis of 20095 patient data

OBJECTIVES

For over a century, a heated debate existed over the possibility of malignant transformation of oral lichen planus (OLP). We performed this meta-analysis to evaluate the malignant potential of OLP and oral lichenoid lesions (OLL) and investigate the possible risk factors for OLP malignant transformation into oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

We searched Medline, Scopus, and Web of Knowledge for relevant observational studies. Data on OLP malignant transformation were calculated as a pooled proportion (PP), using the Der-Simonian Liard method. We performed subgroup analyses by OLP diagnostic criteria, site, and clinical type, using Open Meta[Analyst] software. Data on possible risk factors for malignant transformation were pooled as odds ratios (ORs), using Comprehensive Meta-Analysis software.

RESULTS

Pooling data for OLP malignant transformation from 57 studies (19,676 patients) resulted in an overall PP of 1.1% [95% CI: 0.9%, 1.4%], while pooling data from 14 recent studies that used the World Health Organization-2003 diagnostic criteria resulted in an overall-PP of 0.9% [95% CI: 0.5%, 1.3%]. The risk of malignant transformation was higher (PP=2.5%, 95% CI [1%, 4%]) in OLL patients (419 patients). A significant increase of malignant transformation risk was noted among smokers (OR=2, 95% CI [1.25, 3.22]), alcoholics (OR=3.52, 95% CI [1.54, 8.03]), and HCV-infected patients (OR=5, 95% CI [1.56, 16.07]), compared to patients without these risk factors.

CONCLUSION

A small subset of OLP patients (1.1%) develop OSCC; therefore, regular follow-up for these patients is recommended. A higher incidence of malignant transformation was found among smokers, alcoholics, and HCV-infected patients; however, these associations should be further investigated.

Increased melatonin in oral mucosal tissue of oral lichen planus (OLP) patients: A possible link between melatonin and its role in oral mucosal inflammation

OBJECTIVE

The existence of extra-pineal melatonin has been observed in various tissues. No prior studies of melatonin in human oral mucosal tissue under the condition of chronic inflammation have been reported. The aim of this study was to investigate the presence of melatonin in oral mucosal tissue of patients with oral lichen planus (OLP) which was considered as a chronic inflammatory immune-mediated disease causing oral mucosal damage and ulcerations.

MATERIALS AND METHODS

Sections from formalin-fixed and paraffin-embedded oral mucosal tissue of OLP patients (n=30), and control subjects (n=30) were used in this study. Immunohistochemical staining was performed and the semiquantitative scoring system was used to assess the levels of arylalkylamine-N-acetyltransferase (AANAT: a rate-limiting enzyme in the biosynthesis pathway of melatonin), melatonin, and melatonin receptor 1 (MT1) in oral mucosa of OLP patients and normal oral mucosa of control subjects.

RESULTS

AANAT, melatonin, and MT1were detected in oral mucosal tissue of OLP patients and control subjects. Immunostaining scores of AANAT, melatonin, and MT1 in oral mucosal tissue of OLP patients were significantly higher than those in control subjects (p=0.002, p<0.001, and p=0.031, respectively).

CONCLUSIONS

Increased levels of AANAT, melatonin, and MT1 in the inflamed oral mucosal tissue of OLP patients imply that chronic inflammation may induce the local biosynthesis of melatonin via AANAT, and may enhance the action of melatonin via MT1.

Comprehensive analysis of the formation and stability of peroxynitrite-derived 8-nitroguanine by LC-MS/MS: Strategy for the quantitative analysis of cellular 8-nitroguanine

Peroxynitrite is a major oxidizing and nitrating biological agent formed at sites of inflammation. Peroxynitrite can cause DNA damage and is thought to contribute to inflammation-related carcinogenesis. This study describes a sensitive and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct determination of peroxynitrite-derived 8-nitroguanine (8-nitroGua) in DNA hydrolysates. This method exhibited a sensitive detection limit of 3 fmol and inter- and intraday imprecision of <10% and was applied to systemically examine the formation and stability of peroxynitrite-derived 8-nitroGua in different DNA substrates under various conditions. The 8-nitroGua formation was maximal at pH 8. The formation rate of 8-nitroGua in different DNA substrates decreased in the order of monodeoxynucleoside>single-stranded DNA>double-stranded DNA. A stability test revealed that the half-life for the depurination of 8-nitroGua from DNA was short and affected by both the temperature and DNA structure. When present in monodeoxynucleoside, the half-life of 8-nitroGua was estimated to be ~6min at 25°C and 2.3h at ~0°C. In single-stranded DNA, the half-life varied from 1.6h at 37°C to 533h at -20°C, whereas the half-life increased from 2.4h at 37°C to 1115h at -20°C in double-stranded DNA. We demonstrated that the measurement of 8-nitroGua in isolated DNA is not practicable because 8-nitroGua is unstable and lost during DNA extraction from cell. Therefore, we suggest that directly detecting cellular 8-nitroGua following nuclear membrane lysis is an alternative measure of the nitrative damage of nucleic acids, accounting for both DNA and RNA lesions within cells.

Urine metabolic profiling for the pathogenesis research of erosive oral lichen planus

OBJECTIVE

Oral lichen planus (OLP) is a relatively common chronic immune-pathological and inflammatory disease and potentially oral precancerous lesion. Erosive OLP patients show the higher rate of malignant transformation than patients with non-erosive OLP. Identifying the potential biomarkers related to erosive OLP may help to understand the pathogenesis of the diseases.

METHODS

Metabolic profiles were compared in control and patient subjects with erosive OLP by using ultra-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF-MS) coupled with pattern recognition methods An integrative analysis was used to identify the perturbed metabolic pathways and pathological processes that may be associated with the disease.

RESULTS

In total, 12 modulated metabolites were identified and considered as the potential biomarkers of erosive OLP. Multiple metabolic pathways and pathological processes were involved in erosive OLP.

CONCLUSION

The dysregulations of these metabolites could be used to explain the pathogenesis of the disease, which could also be the potential therapeutic targets for the disease.

Evaluation of Potential Risk Factors that contribute to Malignant Transformation of Oral Lichen Planus: A Literature Review

AIM

Many studies have suggested that a lesion originally diagnosed as oral lichen planus (OLP) has different possibilities of undergoing malignant transformation in time, although these findings remain a controversial issue; for example, some studies reported different values of potential malignancy of OLP.

INTRODUCTION

World Health Organization (WHO) classifies OLP as a "potentially malignant disorder" with unspecified malignant transformation risk, and suggests that OLP patients should be closely monitored. Numerous studies have attempted to confirm the malignant transformation potential of OLP.

REVIEW RESULTS

The Cochrane Controlled Trials Register, Medline and EMBASE databases, PubMed, Google Scholar, Ovid, Up To Date, BMJ Clinical Evidence, MD Consult, and Science Direct were searched for papers published between 1997 and 2015. The medical subject heading search terms were "lichen planus," "oral lichen planus," "erosive oral lichen planus," "dysplasia," "oral precancerous condition," "oral premalignant condition," oral cancer, oral squamous cell carcinoma (OSCC), and atrophic lichen planus. A total of 120 English language abstracts were reviewed, and 50 relevant articles identified. Because of the extensive literature on the association between OLP and SCC, we have divided the data into genetic and non-genetic factors for more accurate assessment.

CONCLUSION

In this evidence base, malignant transformation ranges from 0 to 37% with a mean of 4.59%. The highest rate of malignancy was noted in erythematosus and erosive lesions. In this way, follow-up of OLP patients could be carried out more efficiently and appropriately.

CLINICAL SIGNIFICANCE

Oral lichen planus is a premalignant lesion. All types of OLP in any site of oral mucosa must be monitored regularly.

Oxidative stress and antioxidant strategies in dermatology

Oxidative stress results from a prooxidant-antioxidant imbalance, leading to cellular damage. It is mediated by free radicals, such as reactive oxygen species or reactive nitrogen species, that are generated during physiological aerobic metabolism and pathological inflammatory processes. Skin serves as a protective organ that plays an important role in defending both external and internal toxic stimuli and maintaining homeostasis. It is becoming increasingly evident that oxidative stress is involved in numerous skin diseases and that antioxidative strategies can serve as effective and easy methods for improving these conditions. Herein, we review dysregulated antioxidant systems and antioxidative therapeutic strategies in dermatology.

Molecular markers in oral lichen planus: A systematic review

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that is usually detected in 0.5–2.2% of the human population. Among these, only 0.5–2.9% of the lesions progress to carcinoma. However, there are no prognostic markers available presently to recognize the increased risk in malignant transformation of the lesions. Selected markers for cell proliferation, adhesion, apoptosis and lymphocytic infiltration were analyzed by immunohistochemistry in addition to static cytometry for DNA content. The concept linking OLP and oral squamous cell carcinoma states that chronic inflammation results in crucial DNA damage, which further progresses to development of carcinoma. Even though in the past decade, enormous information has been accumulated on malignant potential of OLP, its transformation still remains unclear. Hence, the purpose of this article was to review cellular and molecular markers to understand the pathogenesis of OLP and its progression toward malignancy.

Evaluation of the Efficacy of Curcumin in the Treatment of Oral Lichen Planus: A Randomized Controlled Trial

INTRODUCTION

Oral Lichen Planus (OLP) is a chronic immunological, mucocutaneous disease with a wide range of clinical appearances. The treatment of oral lichen planus is often difficult and disappointing.

AIM

We have studied the efficacy of curcumin, a low molecular weight flavonoid with anti-inflammatory and anti-oxidant activities, in the treatment of OLP.

MATERIALS AND METHODS

In this study, a randomized, double-blind, placebo-controlled trial was conducted with a total of 20 OLP patients. The patients were randomly divided into two groups, each treated with curcumin tablets at a dose of 2000 mg/day or placebo for a period of four weeks. Furthermore, the patients of both groups received routine treatment for OLP (i.e. Mouthwash Dexamethasone 0.5 mg and suspension Nystatin 100,000 Units). The baseline data were recorded for each patient. Patients were evaluated on day 14 and after completing the course of treatment. Pain and burning sensation were measured based on the Visual Analogue Scale, and the Thongprasom Index was used for clinical improvement and healing. Mann-Whitney and independent t-test were used to compare the responses between the two groups, p-value < 0.05 was considered statistically significant.

RESULTS

Our analyses demonstrated no significant difference between the curcumin and placebo treated groups.

CONCLUSION

In conclusion, curcumin had no detectable effect in the treatment of OLP. However, a higher dose of curcumin administration and other forms of curcumin with improved bioavailability may be considered in future studies.

Oral lichen planus

Lichen planus is an inflammatory mucocutaneous disease that can affect the skin, hair, nails, and mucosal surfaces. Mucosal sites of involvement include oral, genital, ocular, otic, esophageal, and, less commonly, bladder, nasal, laryngeal, and anal surfaces. Oral lichen planus is a mucosal variant of lichen planus, which tends to affect women more often than men, with a typically more chronic course and potential for significant morbidity. Treatment can be challenging, and there is potentially a low risk of malignant transformation; however, therapeutic benefits can be obtained with various topical and systemic medications. Clinical monitoring is recommended to ensure symptomatic control. Increasing awareness and recognition of this entity have continued to fuel advances in therapy and in our understanding of the disease.

The Effects of NBF Gingival Gel Application in the Treatment of the Erosive Lichen Planus: Case Report

The therapy of erosive lichen planus (ELP) has been particular problem in the treatment of oral lesions. This case of ELP in male patient 29 years old was treated with topic application of the NBF gingival gel, three times a day after meal, previously rinsed with Clorhexidine gluconate 0.12%. After 5 days of treatment, initial improvements were recorded, and after two weeks of application of the NBF gingival gel we observed significant improvement. Clinical monitoring after the fifth day showed mild epithelialization of the eroded mucosa, yet still present erythematous base of the lesion. After the second week the erythema area was significantly reduced and the eroded surfaces of the mucosa were minimal, measured less than 0.5 mm. After the third week there were no erosions to detect on the oral mucosa, yet still present vague redness, which completely pulled after the fourth week. Treatment ended after the fifth week when the topical application of the NBF gingival gel was terminated, and therapy was done, and clinically achieved effects remained stable even after the third month of the treatment. Topic application of the NBF gingival gel with ELP patients showed positive clinical effects in relatively short time period.

Production and physiological role of NO in the oral cavity

Nitric oxide (NO) is a free radical which is produced from a wide variety of cells and tissues in the human body. NO is involved in the regulation of many physiological processes, such as vascular relaxation, neurotransmission, immune regulation, and cell death. NO is generated by nitric oxide synthase (NOS), which has three identified isoforms: neuronal type NOS (nNOS), endothelial type NOS (eNOS), and inducible type NOS (iNOS). Different isoforms are expressed depending on the organs, tissues, and cells, and investigation of the types and functions of enzymes expressed in various tissues is underway. The oral cavity is a space in which marked changes have been detected in NO levels, and each tissue is constantly influenced by NO. NO is a component of saliva and is produced by oral bacteria in the oral cavity and released by NOS expressed in oral mucosa. NOS isoforms expressed under normal conditions differ among the oral organs. In addition, the overexpression of NOS was involved in carcinogenesis and tumor growth progression. This review summarized the expression of NOS and functions of NO in oral cavity organs, and their roles in diseases and the influences of treatments.

Oxidative stress and its significant roles in neurodegenerative diseases and cancer

Reactive oxygen and nitrogen species have been implicated in diverse pathophysiological conditions, including inflammation, neurodegenerative diseases and cancer. Accumulating evidence indicates that oxidative damage to biomolecules including lipids, proteins and DNA, contributes to these diseases. Previous studies suggest roles of lipid peroxidation and oxysterols in the development of neurodegenerative diseases and inflammation-related cancer. Our recent studies identifying and characterizing carbonylated proteins reveal oxidative damage to heat shock proteins in neurodegenerative disease models and inflammation-related cancer, suggesting dysfunction in their antioxidative properties. In neurodegenerative diseases, DNA damage may not only play a role in the induction of apoptosis, but also may inhibit cellular division via telomere shortening. Immunohistochemical analyses showed co-localization of oxidative/nitrative DNA lesions and stemness markers in the cells of inflammation-related cancers. Here, we review oxidative stress and its significant roles in neurodegenerative diseases and cancer.

Brief communication (Original). Trefoil factor expression by immunohistochemistry in patients with oral lichen planus

Background: Oral lichen planus (OLP) is a chronic immune-mediated inflammatory disease that usually causes oral mucosal damage. OLP has been considered to be a potentially malignant disorder associated with an increased risk for oral cancer. Trefoil factors (TFFs) are mainly synthesized by mucin-producing epithelial cells. Expression of TFFs in oral epithelia is thought to be an essential factor in protection against oral mucosal damage. However, very little is known about the connection between tissue damage of oral mucosa in OLP patients and expression of TFFs.

Objectives: To determine levels of TFF expression in oral mucosa from patients with OLP.

Methods: Tissue samples were collected from 35 patients with normal oral mucosa (controls) and 35 patients with OLP. An immunohistochemical method was used to determine the expression of the 3 TFFs (TFF1, 2, and 3) in mucosal tissues of the oral cavity.

Results:TFF2 and TFF3 expression in oral epithelia were significantly decreased in OLP patients (Mann- Whitney U test; P = 0.006, and P = 0.002, respectively). There were no significant differences in TFF1 expression between OLP patients and control subjects.

Conclusion: The present study demonstrated reduced expression of TFF2 and TFF3 in oral epithelia of OLP patients. These outcomes support our previous observations that chronic inflammation may play a major role in downregulation of TFF expression, which may be associated with oral mucosal damage in OLP patients.

Epidermal growth factor receptor expression in different subtypes of oral lichenoid disease

The oral lichenoid disease (OLD) includes different chronic inflammatory processes such as oral lichen planus (OLP) and oral lichenoid lesions (OLL), both entities with controversial diagnosis and malignant potential. Epidermal growth factor receptor (EFGR) is an important oral carcinogenesis biomarker and overexpressed in several oral potentially malignant disorders. Objectives: To analyze the EGFR expression in the OLD to find differences between OLP and OLL, and to correlate it with the main clinical and pathological features. Material and Methods: Forty-four OLD cases were studied and classified according to their clinical (Group C1: only papular lesions / Group C2: papular and other lesions) and histopathological features (Group HT: OLP-typical / Group HC: OLP-compatible) based in previous published criteria. Standard immunohistochemical identification of EGFR protein was performed. Comparative and descriptive statistical analyses were performed. Results: Thirty-five cases (79.5%) showed EGFR overexpression without significant differences between clinical and histopathological groups (p<0.05). Histological groups showed significant differences in the EGFR expression pattern (p=0.016). Conlusions: All OLD samples showed high EGFR expression. The type of clinical lesion was not related with EGFR expression; however, there are differences in the EGFR expression pattern between histological groups that may be related with a different biological profile and malignant risk.

Key words:Oral lichenoid disease, oral lichen planus, oral lichenoid lesion, oral carcinogenesis, EGFR.

Topical treatment of oral lichen planus with anthocyanins

BACKGROUND

Oxidative stress is involved in oral lichen planus (OLP) pathogenesis; meanwhile anthocyanins are natural antioxidants present in grapes skin.

OBJECTIVES

The aim of this research was to verify the utility of anthocyanins, extracted from grapes skin, for the local treatment of oral lichen planus and to compare it with clobetasol propionate- neomycin -nystatin cream (CP-NN).

STUDY DESIGN

Prospective, non-randomized study, with control group. Fifty-two patients with OLP were included. We divided patients into two categories: erosive oral lichen planus (EOLP) and non erosive oral lichen planus (NEOLP). 38 had EOLP (17 cases and 21 controls) and 14 presented NEOLP types (9 cases and 5 controls).Cases received local treatment with anthocyanins from grapes and controls, were treated with CP-NN. The clinical evolution of patients was followed up during six months.

RESULTS

The patients had a therapeutic response with anthocyanins. This was better than CP-NN treatment for patients with EOLP, in improving the involvement score of the oral mucosa and in the morphometric study of the affected areas. In EOLP there were no statistically significant differences in: therapeutic response time, the evolution of pain, or the relapse rate between the two groups. With respect to the treatment of NEOLP there was improved pain relief in the group treated with anthocyanins. This was not observed with CP-NN. The resting analized variables showed no significant difference with both treatments.

CONCLUSIONS

OLP has a favorable response to local treatment with anthocyanins from grapes. We found an equal to or better response than with CP-NN treatment. Many of our patients have systemic diseases, which may contraindicate the use of steroids. With regard to this particular group, the use of this natural antioxidant present in the diet is considered advantageous.

Melatonin in the oral cavity: physiological and pathological implications

BACKGROUND AND OBJECTIVES

The purpose of this article was to summarize what is known about the function of melatonin in the oral cavity.

MATERIAL AND METHODS

Databases were searched for the relevant published literature to 30 November, 2013. The following search items were used in various combinations: melatonin, gingiva, periodontium, inflammation, herpes, alveolar bone, periodontal ligament, dental implants, xerostomia, methacrylate, chlorhexidine, cancer. The literature uncovered is summarized herein.

RESULTS

Salivary melatonin levels exhibit a circadian rhythm with highest values at night. Melatonin has both receptor-mediated and receptor-independent actions in cells of the oral cavity. Melatonin is released into the saliva by the acinar cells of the major salivary glands and via the gingival fluid. Functions of melatonin in the oral cavity are likely to relate primarily to its anti-inflammatory and antioxidant activities. These actions may suppress inflammation of the gingiva and periodontium, reduce alveolar bone loss, abrogate herpes lesions, enhance osteointegration of dental implants, limit oral cancer, and suppress disorders that have a free radical component. Sublingual melatonin tablets or oral melatonin sprays and topical melatonin-containing gel, if used on a regular basis, may improve overall oral health and reduce mucosal lesions.

CONCLUSION

Collectively, the results indicate that endogenously-produced and exogenously-applied melatonin are beneficial to the oral cavity.

Action of melatonin on squamous cell carcinoma and other tumors of the oral cavity (Review)

Melatonin (MLT; N-acetyl-5-metoxy-tryptamine) is a hormone that is principally synthesized in the pineal gland. MLT has been shown to exhibit a variety of functions. The hormone, which is a free radical scavenger, plays an immunomodulatory role, stimulates the proliferation and synthesis of type I collagen and promotes bone formation. Moreover, MLT exerts oncostatic activity through several biological mechanisms, including antiproliferative functions, stimulation of anticancer immunity, modulation of oncogene expression and anti-inflammatory, antioxidant and antiangiogenic effects. In addition, MLT inhibits human cancer cell growth in culture, and previous clinical studies have also confirmed its anticancer properties in vivo. With regard to the underlying mechanisms of MLT in tumor processes, including oral cavity tumors such as epidermoid carcinoma, knowledge of the role played by the MT1 and 2 membrane receptors, MT3 and the calmodulin cytosolic binding sites, as well as the nuclear receptors of the RZR/ROR family, is increasing. It has been hypothesized that exogenous restoration of MT1 (MTNR1A) expression inhibits the growth of oral squamous cell carcinoma cells lacking the expression of the receptor. The tumor suppressing functions of MLT and the presence of the MT1 receptor in various tumors indicate that the receptor may play a pivotal role in oral carcinogenesis. The current review discusses the clinical significance of MLT in oral cancer.

DNA damage in inflammation-related carcinogenesis and cancer stem cells

Infection and chronic inflammation have been recognized as important factors for carcinogenesis. Under inflammatory conditions, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from inflammatory and epithelial cells and result in oxidative and nitrative DNA damage, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-nitroguanine. The DNA damage can cause mutations and has been implicated in the initiation and/or promotion of inflammation-mediated carcinogenesis. It has been estimated that various infectious agents are carcinogenic to humans (IARC group 1), including parasites (Schistosoma haematobium (SH) and Opisthorchis viverrini (OV)), viruses (hepatitis C virus (HCV), human papillomavirus (HPV), and Epstein-Barr virus (EBV)), and bacterium Helicobacter pylori (HP). SH, OV, HCV, HPV, EBV, and HP are important risk factors for bladder cancer, cholangiocarcinoma, hepatocellular carcinoma, cervical cancer, nasopharyngeal carcinoma, and gastric cancer, respectively. We demonstrated that 8-nitroguanine was strongly formed via inducible nitric oxide synthase (iNOS) expression at these cancer sites of patients. Moreover, 8-nitroguanine was formed in Oct3/4-positive stem cells in SH-associated bladder cancer tissues and in Oct3/4- and CD133-positive stem cells in OV-associated cholangiocarcinoma tissues. Therefore, it is considered that oxidative and nitrative DNA damage in stem cells may play a key role in inflammation-related carcinogenesis.

Salivary biomarkers of oxidative stress and quality of life in patients with oral lichen planus

AIM

Lichen planus is a T cell-mediated chronic inflammatory disease of unknown etiology. The objective of the present study was to evaluate the status of oxidative stress in saliva and the anti-oxidant defense system in relation to quality of life parameters in patients with oral lichen planus (OLP).

METHODS

The sample consisted of 70 patients (40 with OLP and 30 control patients). The average age of OLP patients was 60 years (9 males and 31 females), and of the control group 57 years (6 males and 24 females). All participants completed the Oral Health Impact Profile-49 quality of life questionnaire. Total anti-oxidant activity and lipid peroxidation products in saliva were evaluated, using ferric reducing anti-oxidant power and thiobarbituric acid reactive substance.

RESULTS

Mean levels of salivary malondialdehyde were higher in the OLP group than the control group (P = 0.001), and total anti-oxidant capacity was lower among OLP patients than control patients (P = 0.02). There was no correlation between Oral Health Impact Profile-49 findings and the oxidative stress parameters studied.

CONCLUSIONS

The results of the present study point to the possible function of oxidative stress in the etiopathogenesis of OLP.

Oxidative and antioxidative mechanisms in oral cancer and precancer: a review

Development of cancer in humans is a multistep process. Complex series of cellular and molecular changes participating in cancer development are mediated by a diversity of endogenous and exogenous stimuli and important amongst this is generation of reactive oxygen species (ROS). Reactive radicals and non-radicals are collectively known as ROS. These can produce oxidative damage to the tissues and hence are known as oxidants in biological system. Many researchers have documented the role of ROS in both initiation and promotion of multistep carcinogenesis. To mitigate the harmful effects of free radicals, all aerobic cells are endowed with extensive antioxidant defence mechanisms. Lowered antioxidant capacity or the oxidant-antioxidant imbalance can lead to oxidative damage to cellular macromolecules leading to cancer. Oral cavity cancer is an important cancer globally and tobacco is the primary etiological factor in its development. Tobacco consumption exposes the oral epithelium to toxic oxygen and nitrogen free radicals that can affect host antioxidant defence mechanisms. Elevated levels of ROS and Reactive Nitrogen Species (RNS) and lowered antioxidants are found in oral precancer and cancer. Protection can be provided by various antioxidants against deleterious action of these free radicals. Treatment with antioxidants has the potential to prevent, inhibit and reverse the multiple steps involved in oral carcinogenesis. This review is an attempt to understand the interesting correlation between ROS and RNS mediated cell damage and enzymatic and non-enzymatic defence mechanisms involved in oral cancer development and its progression and the use of antioxidants in oral cancer prevention and treatment.

Macrophage-tumor cell interactions regulate the function of nitric oxide

Tumor cell-macrophage interactions change as the tumor progresses, and the generation of nitric oxide (NO) by the inducible nitric oxide synthase (iNOS) plays a major role in this interplay. In early stages, macrophages employ their killing mechanisms, particularly the generation of high concentrations of NO and its derivative reactive nitrogen species (RNS) to initiate tumor cell apoptosis and destroy emerging transformed cells. If the tumor escapes the immune system and grows, macrophages that infiltrate it are reprogramed in situ by the tumor microenvironment. Low oxygen tensions (hypoxia) and immunosuppressive cytokines inhibit iNOS activity and lead to production of low amounts of NO/RNS, which are pro-angiogenic and support tumor growth and metastasis by inducing growth factors (e.g., VEGF) and matrix metalloproteinases (MMPs). We review here the different roles of NO/RNS in tumor progression and inhibition, and the mechanisms that regulate iNOS expression and NO production, highlighting the role of different subtypes of macrophages and the microenvironment. We finally claim that some tumor cells may become resistant to macrophage-induced death by increasing their expression of microRNA-146a (miR-146a), which leads to inhibition of iNOS translation. This implies that some cooperation between tumor cells and macrophages is required to induce tumor cell death, and that tumor cells may control their fate. Thus, in order to induce susceptibility of tumors cells to macrophage-induced death, we suggest a new therapeutic approach that couples manipulation of miR-146a levels in tumors with macrophage therapy, which relies on ex vivo stimulation of macrophages and their re-introduction to tumors.

Triology of nitric oxide, mast cell and stress in pathogenesis of oral lichen planus

INTRODUCTION

Oral Lichen planus (OLP) is chronic, autoimmune, mucocutaneous disease. Numerous etiological factors have been proposed, but an authoritative and exact source of the disease has not been brought forward. Reactive nitrogen species (RNS), mast cell (MC) and stress are considered to play a key role in inflammation-mediated carcinogenesis generating nitric oxide (NO).

AIM

To evaluate the salivary NO levels, mast cells and stress levels and to correlate them in pathogenesis of OLP.

MATERIALS AND METHODS

The study was conducted using saliva samples of patients. The study consisted of two groups: Group-I constituted the subjects with OLP group (n=25) and group II comprised the control group (n=25). The saliva of the patients was evaluated using Griess Reagent and Spectrophotometer, MC count done by using special stains, and stress levels measured using DASS Scale.

RESULTS

The difference between the means was found to be highly significant (P < 0.05). The intergroup comparison of optical density (OD) values, a mast cell count and stress level was found to be highly significant.

CONCLUSION

Salivary NO, increase in mast cell count and stress has a definitive role in OLP pathogenesis.

Salivary markers of oxidative stress in patients with oral premalignant lesions

The aetiology of oral premalignant lesions is unknown. Oxidative stress is associated with inflammation and cancerogenesis. The aim of our study was to compare salivary markers of oxidative and carbonyl stress in patients with oral premalignant lesions and age-matched healthy controls. Unstimulated saliva samples were collected from 16 patients with oral premalignant lesions (leukoplakia, lichen planus, erythroplakia) and 16 age-matched healthy controls. Biochemical analysis included measurement of thiobarbituric acid reacting substances (TBARS), advanced oxidation protein products (AOPP), advanced glycation endproducts (AGEs) and total antioxidant capacity (TAC). Salivary RNA was analyzed using real time PCR. Salivary TBARS and AGEs were significantly higher in patients than in controls. No differences were found in AOPP. TAC and expression of superoxide dismutase were lower in patients than in age-matched controls. Other analyzed transcripts (vascular endothelial growth factor, sialotransferase, neuraminidase) did not differ between patients and the control group. Markers of lipoperoxidation and carbonyl stress were increased in patients with oral premalignant lesions. Decreased antioxidant status potentially due to decreased expression of antioxidant enzymes might be responsible for these findings. Our results might point to the aetiology or pathogenesis of oral premalignant lesions as well as to the mechanism of transition to oral carcinoma.

Melatonin: a novel indolamine in oral health and disease

This paper attempts to summarise the findings accumulated within the last few years concerning the hormone of darkness “melatonin.” Based on its origin, from the pineal gland until recently it was portrayed exclusively as a hormone. Due to its lipophilic nature, it is accessible to every cell. Thus, in the classic sense it is a cell protector rather than a hormone. Recent studies, by Claustrat et al. (2005), detected few extrapineal sources of melatonin like retina, gastrointestinal tract, and salivary glands. Due to these sources, research by Cutando et al. (2007), is trying to explore the implications of melatonin in the oral cavity, in addition to its physiologic anti-oxidant, immunomodulatory and oncostatic functions at systemic level that may be receptor dependent or independent. Recently, certain in vivo studies by Shimozuma et al. (2011), detected the secretion of melatonin from salivary glands further emphasising its local activity. Thus, within our confines the effects of melatonin in the mouth are reviewed, adding a note on therapeutic potentials of melatonin both systemically and orally.

Melatonin and oral cavity

While initially the oral cavity was considered to be mainly a source of various bacteria, their toxins and antigens, recent studies showed that it may also be a location of oxidative stress and periodontal inflammation. Accordingly, this paper focuses on the involvement of melatonin in oxidative stress diseases of oral cavity as well as on potential therapeutic implications of melatonin in dental disorders. Melatonin has immunomodulatory and antioxidant activities, stimulates the proliferation of collagen and osseous tissue, and acts as a protector against cellular degeneration associated with aging and toxin exposure. Arising out of its antioxidant actions, melatonin protects against inflammatory processes and cellular damage caused by the toxic derivates of oxygen. As a result of these actions, melatonin may be useful as a coadjuvant in the treatment of certain conditions of the oral cavity. However, the most important effect of melatonin seems to result from its potent antioxidant, immunomodulatory, protective, and anticancer properties. Thus, melatonin could be used therapeutically for instance, locally, in the oral cavity damage of mechanical, bacterial, fungal, or viral origin, in postsurgical wounds caused by tooth extractions and other oral surgeries. Additionally, it can help bone formation in various autoimmunological disorders such as Sjorgen syndrome, in periodontal diseases, in toxic effects of dental materials, in dental implants, and in oral cancers.

Nitric oxide and oral cancer: a review

Nitric oxide (NO), a short-lived, endogenously produced gas, plays key role in various physiological as well as pathological processes. NO-inducing cell signaling events within the cell producing it and the diffusibility of it in other cells have led to the discovery of various physiological functions of NO including vasodilation, respiration, cell migration, immune response and apoptosis. On the other hand, excessive and unregulated NO synthesis has been implicated in many pathophysiological conditions including cancer. Research on NO, during the past few years is one of the growing areas in cancer biology. The high incidence of oral cancer and precancer has been linked with habits of tobacco chewing and smoking and NO has been said as the "messenger of death" in tobacco related diseases. NO seems to play a part in various stages of carcinogenesis from initiation to progression. However, there is considerable controversy and confusion in understanding its role in cancer biology. It is said to have both, tumoricidal as well as tumor promoting effects and these depend on its timing, location and concentration. Further, NO has also been shown to have antitumor, chemopreventive and therapeutic abilities. Here is an overview in which efforts are made to understand the role of this molecule in oral carcinogenesis.

Oral lichen planus as a preneoplastic inflammatory model

Oral lichen planus (OLP) is a chronic oral inflammatory disease of unknown etiology. According to reports, 1-2% of OLP patients develop oral squamous cell carcinoma (OSCC) in the long run. While World Health Organization (WHO) classifies OLP as “a potentially malignant disorder,” it is still a matter of debate which mechanisms drive OLP to such a condition. The current hypothesis connecting OLP and OSCC is that chronic inflammation results in crucial DNA damage which over time results in cancer development. Initial studies investigating the OLP and OSCC link were mainly retrospective clinical studies. Over the past years, several amount of information has accumulated, mainly from molecular studies on the OLP malignant potential. This article is a critical review of whether OLP has a malignant potential and, therefore, represents a model of preneoplastic inflammation.

Role of nitrative and oxidative DNA damage in inflammation-related carcinogenesis

Chronic inflammation induced by biological, chemical, and physical factors has been found to be associated with the increased risk of cancer in various organs. We revealed that infectious agents including liver fluke, Helicobacter pylori, and human papilloma virus and noninfectious agents such as asbestos fiber induced iNOS-dependent formation of 8-nitroguanine and 8-oxo-7, 8-dihydro-2′-deoxyguanosine (8-oxodG) in cancer tissues and precancerous regions. Our results with the colocalization of phosphorylated ATM and γ-H2AX with 8-oxodG and 8-nitroguanine in inflammation-related cancer tissues suggest that DNA base damage leads to double-stranded breaks. It is interesting from the aspect of genetic instability. We also demonstrated IL-6-modulated iNOS expression via STAT3 and EGFR in Epstein-Barr-virus-associated nasopharyngeal carcinoma and found promoter hypermethylation in several tumor suppressor genes. Such epigenetic alteration may occur by controlling the DNA methylation through IL-6-mediated JAK/STAT3 pathways. Collectively, 8-nitroguanine would be a useful biomarker for predicting the risk of inflammation-related cancers.

Immunochemical detection of oxidatively damaged DNA

Oxidatively damaged DNA is implicated in various diseases, including neurodegenerative disorders, cancer, diabetes, cardiovascular and inflammatory diseases as well as aging. Several methods have been developed to detect oxidatively damaged DNA. They include chromatographic techniques, the Comet assay, (32)P-postlabelling and immunochemical methods that use antibodies to detect oxidized lesions. In this review, we discuss the detection of 8-oxo-7,8-dihydro-29-deoxyguanosine (8-oxodG), the most abundant oxidized nucleoside. This lesion is frequently used as a marker of exposure to oxidants, including environmental pollutants, as well as a potential marker of disease progression. We concentrate on studies published between the years 2000 and 2011 that used enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry to detect 8-oxodG in humans, laboratory animals and in cell lines. Oxidative damage observed in these organisms resulted from disease, exposure to environmental pollutants or from in vitro treatment with various chemical and physical factors.