Salivary Biomarkers and Their Application in the Diagnosis and Monitoring of the Most Common Oral Pathologies.

Saliva is a highly versatile biological fluid that is easy to gather in a non-invasive manner-and the results of its analysis complement clinical and histopathological findings in the diagnosis of multiple diseases. The objective of this review was to offer an update on the contribution of salivary biomarkers to the diagnosis and prognosis of diseases of the oral cavity, including oral lichen planus, periodontitis, Sjögren's syndrome, oral leukoplakia, peri-implantitis, and medication-related osteonecrosis of the jaw. Salivary biomarkers such as interleukins, growth factors, enzymes, and other biomolecules have proven useful in the diagnosis and follow-up of these diseases, facilitating the early evaluation of malignization risk and the monitoring of disease progression and response to treatment. However, further studies are required to identify new biomarkers and verify their reported role in the diagnosis and/or prognosis of oral diseases.

Different expression patterns of carbonic anhydrase IX in oral lichen planus and leukoplakia.

Tumor hypoxia is an important indicator of cancer prognosis. Among the different genes that are upregulated by hypoxia is carbonic anhydrase IX, which combines carbon dioxide and water to form bicarbonate and hydrogen. Although expression of this enzyme is very low in normal tissues, carbonic anhydrase IX is overexpressed in several types of cancer. The aim of the present work was to analyze carbonic anhydrase IX expression in the two most frequent potentially malignant oral disorders: oral lichen planus and oral leukoplakia. Immunohistochemical analysis of oral lichen planus and oral leukoplakia biopsies was performed using anticarbonic anhydrase IX antibody. Samples of normal mucosa served as controls. Statistical analysis was performed by Fischer's exact test. The enzyme was detected in the epithelium of both lesions. The staining was more intense in the basal layer and decreased towards the surface in oral lichen planus. Conversely, the most intense reaction was observed in the superficial layers in leukoplakia, and staining intensity decreased towards the basal membrane. No carbonic anhydrase IX expression was seen in normal mucosa samples. Carbon anhydrase IX expression in lichen and leukoplakia epithelia shows that hypoxia plays a role in the pathogenesis of both lesions. The different distribution patterns provides further evidence of the different biological behavior of these two entities, which under certain circumstances can have similar clinical and histological features.

La hipoxia tumoral es un importante indicador de pronóstico en cáncer. Entre los distintos genes que son activados por hipoxia, uno de los principales es la anhidrasa carbónica IX (CAIX), que combina CO2 con H2O para sintetizar HCO3 y H+. Aunque la expresión de esta enzima es muy baja en tejidos normales, se sobreexpresa en varios tipos de cáncer. La finalidad del presente trabajo fue analizar la expresión de CAIX en las dos lesiones orales potencialmente malignas más frecuentes: el liquen plano y la leucoplasia. Se utilizó una técnica inmuno histoquímica con un anticuerpo específico contra CAIX, en biopsias de liquen plano oral y leucoplasia oral. Se utilizaron mucosas normales como controles. Se realizaron análisis estadísticos utilizando test exacto de Fischer. La identificación de la enzima fue positiva en el epitelio de ambas lesiones. En los líquenes la reacción es más intensa en los estratos basales, disminuyendo hacia la superficie. Inversamente, las leucoplasias mostraron marcación más intensa en estratos superficiales, con disminución hacia la membrana basal. Las mucosas normales resultaron negativas. La expresión de CAIX en el epitelio de líquenes y leucoplasias indica que la hipoxia juega algún papel en la patogenia de ambas lesiones. El diferente patrón de distribución es una evidencia más del diferente comportamiento biológico de dos entidades las cuales en ciertas circunstancias pueden manifestar cuadros clínicos e histológicos semejantes.

Increased salivary aldehyde dehydrogenase 1 in non-reticular oral lichen planus.

BACKGROUND:: Oral lichen planus is a potentially malignant disorder. One of the malignant transformation markers is cancer stem cells. One of the proposed marker for the detection of cancer stem cells's in head and neck cancer is aldehyde dehydrogenase. Recently it is shown that aldehyde dehydrogenase 1 expression in tissue samples is associated with oral lichen planus malignant transformation. OBJECTIVE:: This study evaluates salivary aldehyde dehydrogenase 1 in oral lichen planus. METHOD:: Thirty patients and 30 age and sex-matched healthy volunteers were recruited. Oral lichen planus was diagnosed based on the modified World Health Organization criteria. Subjects in the case group were divided into reticular and non-reticular forms. Unstimulated salivary samples were collected at 10-12 AM. Saliva concentrations of aldehyde dehydrogenase 1 were measured by ELISA. RESULTS:: The differences between aldehyde dehydrogenase levels in the oral lichen planus group compared with the control group were not significant but aldehyde dehydrogenase in non-reticular oral lichen planus was significantly higher than that of the reticular form. LIMITATIONS OF THE STUDY:: This is a cross-sectional study, thus longitudinal studies in oral lichen planus may present similar or different results. CONCLUSIONS:: The mechanism of malignant transformation in oral lichen planus is not defined. Previous analyses revealed that the aldehyde dehydrogenase 1 expression is significantly correlated with increased risk of transformation. This finding is consistent with our results because in the erosive and ulcerative forms of oral lichen planus, which have an increased risk of transformation, salivary aldehyde dehydrogenase 1 was overexpressed. A higher salivary aldehyde dehydrogenase level in non-reticular oral lichen planus can be a defensive mechanism against higher oxidative stress in these groups. Aldehyde dehydrogenase may be one of the malignant transformation markers in oral lichen planus. Further studies are needed for introducing aldehyde dehydrogenase as a prognostic indicator in certain lesions.

Increased salivary aldehyde dehydrogenase 1 in non-reticular oral lichen planus

Abstract: Background: Oral lichen planus is a potentially malignant disorder. One of the malignant transformation markers is cancer stem cells. One of the proposed marker for the detection of cancer stem cells's in head and neck cancer is aldehyde dehydrogenase. Recently it is shown that aldehyde dehydrogenase 1 expression in tissue samples is associated with oral lichen planus malignant transformation. Objective: This study evaluates salivary aldehyde dehydrogenase 1 in oral lichen planus. Method: Thirty patients and 30 age and sex-matched healthy volunteers were recruited. Oral lichen planus was diagnosed based on the modified World Health Organization criteria. Subjects in the case group were divided into reticular and non-reticular forms. Unstimulated salivary samples were collected at 10-12 AM. Saliva concentrations of aldehyde dehydrogenase 1 were measured by ELISA. Results: The differences between aldehyde dehydrogenase levels in the oral lichen planus group compared with the control group were not significant but aldehyde dehydrogenase in non-reticular oral lichen planus was significantly higher than that of the reticular form. Limitations of the study: This is a cross-sectional study, thus longitudinal studies in oral lichen planus may present similar or different results. Conclusions: The mechanism of malignant transformation in oral lichen planus is not defined. Previous analyses revealed that the aldehyde dehydrogenase 1 expression is significantly correlated with increased risk of transformation. This finding is consistent with our results because in the erosive and ulcerative forms of oral lichen planus, which have an increased risk of transformation, salivary aldehyde dehydrogenase 1 was overexpressed. A higher salivary aldehyde dehydrogenase level in non-reticular oral lichen planus can be a defensive mechanism against higher oxidative stress in these groups. Aldehyde dehydrogenase may be one of the malignant transformation markers in oral lichen planus. Further studies are needed for introducing aldehyde dehydrogenase as a prognostic indicator in certain lesions.

Elucidating the role of Cyclooxygenase-2 in the pathogenesis of oral lichen planus - an immunohistochemical study with supportive histochemical analysis.

OBJECTIVE: Oral lichen planus (OLP) is a chronic, inflammatory disorder that affects the oral mucous membrane. During an inflammatory response, several chemokines and cytokines are released by the cells of the immune system. Activation of MMPs, along with mast cell-derived chymase and tryptase, degrades the basement membrane structural proteins, resulting in basement membrane breaks. AIM: To investigate the association between the COX-2 expressions, presence of intact or degranulating mast cells within the connective tissue and the extent of basement membrane discontinuity in OLP cases. METHODS: This study included a total of 50 formalin-fixed paraffin-embedded specimens (FFPE) of histologically confirmed cases of idiopathic oral lichen planus. A retrospective cross-sectional analysis was carried out by immunohistochemistry to study the epithelial expression of COX-2 and by the use of special stains such as toluidine blue and periodic acid-Schiff (PAS) to study the mast cell count and basement membrane changes in the oral mucosal tissue, respectively. RESULTS: There was a significant (P = 0.03) association between the COX-2 expressions and mast cell count. As the intensity of COX-2 expression increased from mild to moderate or severe, the number of mast cell count almost doubled. CONCLUSION: Interaction between upregulation of COX-2, mast cell and basement membrane sets a vicious cycle which relates to the chronic nature of the disease. Inhibitors of COX-2 may reduce the inflammatory process preceding the immune dysregulation in OLP.

miR-125b inhibits keratinocyte proliferation and promotes keratinocyte apoptosis in oral lichen planus by targeting MMP-2 expression through PI3K/Akt/mTOR pathway.

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that involves the degeneration of keratinocytes. However, the etiology and mechanisms of OLP pathogenesis have not been fully elucidated. In this study, we used keratinocytes HaCaT stimulated with lipopolysaccharide (LPS) to mimic a local OLP immune environment, and investigated the regulatory role of miR-125b in keratinocyte proliferation and apoptosis under OLP conditions. Immunohistochemical analysis and quantitative real-time PCR (qRT-PCR) assay showed that MMP-2 expression was up-regulated and miR-125b expression was down-regulated in both OLP mucosa tissues and LPS-incubated HaCaT cells. Western blot analysis indicated that miR-125b overexpression suppressed LPS-induced MMP-2 expression in HaCaT cells. Molecularly, our results confirmed that MMP-2 is a target gene of miR-125b in HaCaT cells. The effect of miR-125b on cell proliferation was revealed by CCK-8 assay, BrdU assay and cell cycle analysis, which illustrated that miR-125b overexpression impeded LPS-induced HaCaT cell proliferation. Flow cytometry analysis further demonstrated that miR-125b overexpression promoted HaCaT cell apoptosis. Moreover, these effects were involved in PI3K/Akt/mTOR activation, as miR-125b overexpression inhibited LPS-enhanced expression of p-Akt and p-mTOR proteins. Taken together, these data confirm that miR-125b might inhibit keratinocyte proliferation and promote keratinocyte apoptosis in OLP pathogenesis by targeting MMP-2 through PI3K/Akt/mTOR pathway.

Cathepsin K expression is increased in oral lichen planus.

BACKGROUND: Oral lichen planus (OLP) is an idiopathic T-cell-mediated mucosal inflammatory disease. Cathepsin K (Cat K) is one of the lysosomal cysteine proteases. It is involved in many pathological conditions, including osteoporosis and cancer. The expression and role of Cat K in OLP are unknown. METHODS: Twenty-five oral mucosal specimens diagnosed histopathologically as OLP and fourteen healthy controls (HC) were used to study the immunohistochemical (IHC) expression of Cat K. Colocalization of Cat K with CD1a, Melan-A, CD68, CD45, mast cell tryptase (MCT), and Toll-like receptors (TLRs) 4 and 9 were studied using double IHC and/or immunofluorescence (IF) staining. Expression of Cat K was also evaluated in OLP tissue samples before and after topical tacrolimus treatment. RESULTS: Cat K was expressed in a higher percentage of cells in the epithelial zone, and the staining intensity was stronger in the stroma in OLP compared to controls (P < 0.001). In OLP, Cat K was present mostly in melanocytes and macrophages and sporadically in basal keratinocytes, endothelial cells, and extracellularly. Cat K was found also in some fibroblasts in HC and OLP samples. Coexpression of Cat K and TLRs 4 and 9 was seen in some dendritic cells (presumably melanocytes) and macrophages. In OLP, tacrolimus treatment reduced the expression of Cat K in the epithelium but increased it in the stroma. CONCLUSIONS: These results suggest that Cat K is involved in the pathogenesis of OLP. Cat K possibly takes part in the modulation of matrix molecules and cellular receptors.

[Expression and significance of p38 mitogen-activated protein kinase in oral lichen planus and oral squamous cell cacinoma].

OBJECTIVE: To assess the differences among the expressions of p38 mitogen activated protein kinases (MAPK), phospho-p38MAPK and nuclear factor kappa B (NF-κB) in oral lichen planus (OLP) and oral squamous cell carcinoma(OSCC). METHODS: In the study, 53 cases of OLP, 45 of OSCC, and 18 controls were obtained and 4-µm-thick histological sections were prepared from formalin-fixed paraffin-embedded tissue blocks.The expressions of p38MAPK,phospho-p38MAPK and NF-κB were detected by immunohistochemistry staining. Furthermore, the expressions of p38MAPK and phospho-p38MAPK were detected using Western blotting analyses in the fresh tissues from 11 cases of OLP, 5 cases of OSCC, and 7 cases of the controls. RESULTS: p38MAPK was over-expressed in the lamina propria, but lowly expressed in the epithelium in OLP group. Phospho-p38MAPK was lower expressed in OLP group than in OSCC and control groups.NF-κB was found over-expressed in the lamina propria in OLP group.p38MAPK was found expressed in all the samples in the 3 groups. The expression of phospho-p38MAPK was observed in 8 (8/11) OLP samples, 5 (5/5) OSCC samples and 4 (4/7) controls by Western blotting, but no significant differences were found within the 3 groups. CONCLUSION: p38MAPK can be detected in normal oral mucosa, OLP and OSCC. Phospho-p38MAPK may be related to the onset and progression of OSCC. The role of p38MAPK in OLP is yet to be revealed.

Sera and salivary matrix metalloproteinases are elevated in patients with vesiculoerosive disease: a pilot study.

BACKGROUND: Oral vesiculoerosive (VE) diseases, such as lichen planus and mucous membrane pemphigoid, are immune-mediated pathoses. Matrix metalloproteinase (MMP)-2 and MMP-9 are elevated in oral lesional biopsy specimens of patients with VE disease. However, the systemic levels and activity of MMP-2 and MMP-9 in this patient population are poorly understood. We performed a pilot study to determine whether the levels and activity of MMP-2 and MMP-9 are elevated in the sera and saliva of patients with VE disease. STUDY DESIGN: We recruited patients with VE disease (n = 10) and healthy controls (n = 19). We collected sera and saliva and performed enzyme-linked immunosorbent assays to measure MMP levels. We used gelatin zymography and Biotrak assays to determine enzyme activity. Data were analyzed using the Mann-Whitney test. RESULTS: There was no difference in the activity of either MMP in the sera or saliva of patients with VE disease compared with controls. Significantly, MMP-2 levels were elevated in the sera of patients with VE disease (P < .0001), whereas MMP-9 was elevated in their saliva (P = .003). CONCLUSIONS: MMP-2 is elevated in the sera of patients with VE disease, and MMP-9 is increased in their saliva. Therefore, these enzymes may be potential markers of disease or therapeutic targets.

Evaluation of prolidase activity and oxidative stress in patients with oral lichen planus and oral lichenoid contact reactions.

OBJECTIVE: The aim of this study was to evaluate prolidase activity and oxidative stress in patients with oral lichen planus (OLP) and oral lichenoid contact reactions (OLCR) using serum and salivary samples and to compare these biomarkers with each other as well as with a group of healthy subjects in order to be able to opine their role in the estimation of OLP and OLCR. PATIENTS AND METHODS: Eighteen recently diagnosed patients with OLP, 32 patients with OLCR and 18 healthy controls with matched periodontal status were recruited to the study. Prolidase activity, lipid peroxidation product malondialdehyde (MDA), sialic acid (SA), and advanced oxidation protein products (AOPPs) levels in both serum and saliva were determined. Additionally, salivary flow rate and its buffering capacity were estimated. Statistical analyses were performed using the chi-square test, t-test, Mann-Whitney U-test, and Spearman's rho correlation coefficient. RESULTS: No statistically significant differences were observed between the study groups and the control group regarding to the basic characteristics and the periodontal status (P > 0.05). There were no statistically significant differences between OLP and OLCR groups regarding to the distribution of lesions' type, severity, and location (P > 0.05). No significant differences were found between the two study groups with regard to Prolidase activity, MDA, SA, and AOPPs (P ˃ 0.05), whereas statistically significant differences were found between the two study groups and the control group with regard to all evaluated parameters except of serum prolidase (P ˂ 0.01). Moderate correlation was found between salivary MDA and the OLP/OLCR lesion severity, whereas a weak correlation was observed between serum SA and the OLP/OLCR lesion severity (P ˂ 0.05). CONCLUSIONS: The findings of this study suggest an increased prolidase activity and oxidative stress and imbalance in the antioxidant defense system in biological fluids of patients with OLP and OLCR when compared with the healthy subjects. Both OLP and OLCR patients revealed almost similar prolidase activity and oxidative stress levels although these two conditions have different etiopathogenesis.

ALK1 expression in oral lichen planus: a possible relation to microvessel density.

OBJECTIVE: To assess the expression of activin receptor-like kinase 1 (ALK1) and investigate its possible relationship with microvessel density (MVD) in different forms of oral lichen planus (OLP) compared to controls' biopsies. METHODS: Biopsies from 20 reticular/papular OLP (R/PLP), 20 atrophic/erosive OLP (A/ELP) patients, and 20 healthy subjects were immunohistochemically analyzed and statistically compared and correlated for ALK1 expression and MVD as assessed by CD34 expression. RESULTS: All OLP specimens revealed the presence of positive cytoplasmic CD34 immunostaining in endothelial cells, with statistically high significant MVD in each of R/PLP (Median; M = 4.40) and A/ELP (M = 7.69) compared to controls (M = 1.16) (P < 0.001). Statistically significant MVD was found in A/ELP compared to R/PLP (P < 0.001). All control specimens revealed negative ALK1 immunostaining of the few inflammatory cells found, while 85% of A/ELP cases and 70% of R/PLP cases showed positively immunostained sections for ALK-1, with statistically significant higher ALK1 expression In A/ELP (M = 1.95) compared to R/PLP (M = 0.86) (P = 0.005). No significant correlation between CD34 and ALK1 was detected in R/PLP (r = 0.081), while a barely moderate positive correlation was found in A/ELP (r = 0.396). CONCLUSIONS: ALK1 expression and MVD are increased in OLP, particularly in A/ELP type.

Serum and Saliva MMP-3 in Patients with OLP and Oral SCC.

BACKGROUND: Matrix metalloproteinase-3 (MMP-3) plays a key role in development of cancer. The purpose of this study was to assess MMP-3 in the serum and saliva of patients with oral lichen planus (OLP) and oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Thirty patients with OLP (8 reticular and 22 erosive forms), and 20 patients with OSCC (6 in low stage and 14 in advanced stage), were enrolled in this study, conducted at the Cancer Department, Clinic of Oral Medicine, Tehran University of Medical Sciences. The serum and saliva MMP-3 was assayed by ELISA method. Statistical analysis of the Student's t-test, ANOVA and Pearson correlation coefficient was performed. The mean saliva and serum levels of MMP-3 were significantly higher in patients with OSCC compared with OLP. RESULTS: The serum and saliva MMP-3 concentrations increased from reticular form of OLP to erosive form of OLP, and increased further to low stage of OSCC and advanced stage of OSCC. Serum MMP-3 correlated significantly with unstimulated (r = 0.310, p = 0.038) and stimulated (r = 0.365, p < 0.026) saliva MMP-3. CONCLUSION: Serum and saliva MMP-3 levels appear associated with OLP and OSCC.

Altered expression of hyaluronan, HAS1-2, and HYAL1-2 in oral lichen planus.

BACKGROUND: Oral lichen planus (OLP) is an immune-mediated mucosal disease of unclear etiology and of unresolved pathogenesis. Hyaluronan (HA) is an extracellular matrix glycosaminoglycan involved in inflammation and tumor progression. However, its presence in OLP has not been reported. We therefore aimed to study the immunohistochemical expression of HA, its receptor CD44, hyaluronan synthases (HAS1-3), and hyaluronidases (HYAL1-2) in OLP. METHODS: The presence of HA, CD44, HAS1-3, and HYAL1-2 was studied by immunohistochemical methods in 55 OLP and 23 control oral mucosal specimens (CTR). The localization, intensity, and differences of the epithelial expression between OLP and CTRs were analyzed. RESULTS: HA and CD44 were found on cell membranes in the epithelial basal and intermediate layers in CTR and OLP specimens. The HA staining intensity was stronger in the basal layer of the epithelium in OLP than in CTRs (P < 0.001). HAS1 (P = 0.001) and HAS2 (P < 0.001) showed stronger staining in the basal and weaker staining in the superficial (P < 0.001) epithelial layers in OLP than in CTRs. The immunostaining of HAS3 was low in both OLP and CTRs. Positive HYAL1 and HYAL2 staining were mainly found in the basal and intermediate epithelial layers, and their intensities were significantly increased in OLP, except HYAL 2 in the intermediate epithelial layer. CONCLUSIONS: HA, HAS1-2, and HYAL1-2 have altered expression in OLP compared to CTRs and may therefore have a role in OLP pathogenesis.

Interferon-γ regulates the function of mesenchymal stem cells from oral lichen planus via indoleamine 2,3-dioxygenase activity.

BACKGROUND: Little is known about mesenchymal stem cells (MSCs) in normal or inflammatory oral mucosal tissues, such as in oral lichen planus (OLP). Our objectives were to identify, isolate, and characterize MSCs from normal human oral mucosa and OLP lesions, and to evaluate indoleamine 2,3 dioxygenase (IDO) activity in mediating immunomodulation of MSCs from these tissues. METHODS: Expressions of MSCs-related markers were examined in isolated cells by flow cytometry. Self-renewal and multilineage differentiations were studied to characterize these MSCs. Interferon-γ (IFN-γ), IDO, and STRO-1 were assessed by immunofluorescence. MSCs from oral mucosa and OLP or IFN-γ-pretreated MSCs were co-cultured with allogeneic mixed lymphocyte reaction assays (MLR). Proliferation and apoptosis of MLR or MSCs were detected by CCK8 and the annexin V-FITC apoptosis detection kit, respectively. IDO expression and activity were measured by real-time PCR, Western blotting, and high-performance liquid chromatography. RESULTS: Isolated cells from oral mucosa and OLP expressed MSC-related markers STRO-1, CD105, and CD90 but were absent for hematopoietic stem cell markers CD34. Besides, they all showed self-renewal and multilineage differentiation capacities. MSCs in OLP presented STRO-1/IDO+ phenotype by immunofluorescence. MSCs and IFN-γ-pretreated MSCs could inhibit lymphocyte proliferation via IDO activity, but not via cell apoptosis. Long-term IFN-γ could also inhibit MSC proliferation via IDO activity. CONCLUSIONS: Mesenchymal stem cells can be isolated from human oral mucosa and OLP tissues. Besides self-renewal and multilineage differentiation properties, these cells may participate in immunomodulation mediated by IFN-γ via IDO activity in human OLP.

Subgrouping of patients with oral lichen planus according to cytochrome P450 enzyme phenotype and genotype.

OBJECTIVE: This study aimed to determine if the activity of the environmentally influenced cytochrome P450 enzyme CYP1A2, alone or in combination with CYP2D6*4 genotype, discriminates subgroups of oral lichen planus (OLP) according to lifestyle factors and clinical manifestations. STUDY DESIGN: A total of 111 patients with OLP were categorized according to normal, low, or high CYP1A2 activity and CYP2D6 4 genotype. Lifestyle parameters influencing the CYP1A2 activity and symptoms and manifestations of OLP were recorded. RESULTS: Of the 111 patients, 21% had low, 65% normal, and 14% high CYP1A2 activity. The high-CYP1A2-activity group was more exposed to CYP1A2 inducers than the low-CYP1A2-activity group. In the normal-CYP1A2-activity group, more patients had a CYP2D6 4 genotype (58%) (P = .02), and they presented more symptoms (P = .003) and gingival lesions (P = .03). More patients in the low-CYP1A2-activity group and without CYP2D6 4 genotype presented red lesions (P = .04). CONCLUSIONS: We suggest CYP2D6 4 genotype as a disease-susceptible genotype and low or high CYP1A2 activity levels as indicators of environmental influence in OLP subgroups.

Aldehyde dehydrogenase 1 expression correlated with malignant potential of oral lichen planus.

Oral lichen planus (OLP) is a potentially malignant disorder associated with an increased risk of oral squamous cell carcinoma (OSCC). The objective of this study was to determine protein expression of cancer stem cell marker aldehyde dehydrogenase 1 (ALDH1) in a series of patients with OLP and evaluate the correlation between ALDH1 expression and the risk of progression to OSCC. In a retrospective study, ALDH1 expression was determined using immunohistochemistry in samples from 101 patients with OLP who received a mean follow-up of 5 years, including 89 patients with untransformed OLP that did not develop into OSCC and 12 patients with malignant transformed OLP that had developed into OSCC. Analysis of 10 cases of normal oral mucosa and 6 cases of postmalignant OSCC form previously diagnosed OLP was also performed. The results showed that ALDH1 expression was observed in 27 (30.3%) of 89 cases of untransformed OLP and in 8 (66.7%) of 12 cases of transformed OLP (P = .021). Aldehyde dehydrogenase 1 was not expressed in normal oral mucosa, but it overexpressed in the 6 cases (100%) of OSCC. Multivariate analysis revealed that ALDH1 expression was significantly associated with a 6.71-fold (95% confidence interval, 1.64-27.42; P = .008) increased risk of malignant transformation. Collectively, ALDH1 expression was significantly associated with malignant transformation in a large series of patients with OLP. Our findings suggested that ALDH1 expression may identify a subgroup of a higher risk of malignant transformation of OLP.

MMP-1, MMP-9, and TIMP-1 levels in oral lichen planus patients with gingivitis or periodontitis.

OBJECTIVE: Oral lichen planus (OLP) is a chronic inflammatory disease of unknown aetiology. The aim of this study was to investigate matrix metalloproteinase (MMP)-1, MMP-9, and MMP inhibitor-1 (TIMP-1) levels in gingival crevicular fluid (GCF) by enzyme-linked immunosorbent assay and to investigate MMP-1, MMP-9, and TIMP-1 levels in gingival tissue by immunohistochemical staining of samples from patients with and without OLP. DESIGN: Twenty-seven patients with OLP (gingivitis, OLPG; chronic periodontitis, OLPP) and thirty healthy non-OLP patients (gingivitis, HG; chronic periodontitis, HP) were included in this study. The MMP-1, MMP-9, and TIMP-1 levels in GCF were determined by enzyme-linked immunosorbent assay. The MMP-1, MMP-9, and TIMP-1 levels in gingival tissue were determined by immunohistochemical staining. RESULTS: The mean levels of MMP-1 and MMP-9 in the GCF of OLPP patients were significantly higher and TIMP-1 was significantly lower than in HP patients; similarly, the mean levels of MMP-1 and MMP-9 were higher and TIMP-1 was significantly lower in OLPG patients than in HG patients. Our findings illustrate that tissue MMP-9 levels were statistically higher and TIMP-1 level were significantly lower in the OLPP group in comparison to the HP group, and the OLPG group in comparison to the HG group. The tissue MMP-1 level in the non-OLP group was found to be lower when compared with the OLP groups. But not statistically significant. CONCLUSIONS: Increased levels of MMP-1 and MMP-9 with decreased levels of TIMP-1 in GCF and increased MMP-1, MMP-9 levels and decreased TIMP-1 levels in the gingival tissue of OLP patients in combination with poor oral hygiene may cause increased tissue breakdown. The results of our study provide information about the effects of the periodontal status on the enzyme profiles in GCF and gingival tissue of OLP and non-OLP patients.

Nitric oxide synthase isoenzyme expression in human oral lichen planus.

The roles of nitric oxide (NO) synthase (NOS) enzyme in pathological mechanisms of the oral cavity are still incompletely understood. The aim of this study was to investigate the expression of the endothelial, neuronal and inducible isoforms of NOS (eNOS, nNOS and iNOS) in oral lichen planus (OLP) development in humans. OLP and healthy oral mucosa biopsies were taken for mRNA and protein analysis of NOS isoenzymes by RT-PCR, western blot and immunohistochemistry. The mRNA and protein levels of eNOS and nNOS were present in all samples, with a significant increase only for eNOS in OLP. The normal oral mucosa exhibited only small amounts of iNOS mRNA and protein, while it showed a significant rise in OLP samples. These results were confirmed by immunohistochemical analysis. Our findings suggest that NO produced by increased eNOS and iNOS expression may have circulatory and immune functions in the development of OLP.