Salivary biomarkers for oral cancer and pre-cancer screening: a review

Non-invasive diagnostic test for lung cancer using biospectroscopy and variable selection techniques in saliva samples

Lung cancer is one of the most commonly occurring malignant tumours worldwide. Although some reference methods such as X-ray, computed tomography or bronchoscope are widely used for clinical diagnosis of lung cancer, there is still a need to develop new methods for early detection of lung cancer. Especially needed are approaches that might be non-invasive and fast with high analytical precision and statistically reliable. Herein, we developed a swab "dip" test in saliva whereby swabs were analysed using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy harnessed to principal component analysis-quadratic discriminant analysis (QDA) and variable selection techniques employing successive projections algorithm (SPA) and genetic algorithm (GA) for feature selection/extraction combined with QDA. A total of 1944 saliva samples (56 designated as lung-cancer positive and 1888 designed as controls) were obtained in a lung cancer-screening programme being undertaken in North-West England. GA-QDA models achieved, for the test set, sensitivity and specificity values of 100.0% and 99.1%, respectively. Three wavenumbers (1422 cm-1, 1546 cm-1 and 1578 cm-1) were identified using the GA-QDA model to distinguish between lung cancer and controls, including ring C-C stretching, CN adenine, Amide II [δ(NH), ν(CN)] and νs(COO-) (polysaccharides, pectin). These findings highlight the potential of using biospectroscopy associated with multivariate classification algorithms to discriminate between benign saliva samples and those with underlying lung cancer.

The effect of the COVID-19 pandemic on the diagnosis and progression of oral cancer

The COVID-19 pandemic placed a significant burden on healthcare resources, limiting care to emergent and essential services only. The objective of this study was to describe the effect of the COVID-19 pandemic on the diagnosis and progression of oral cancer lesions in Montreal, Canada. A retrospective analysis of health records was performed. Patients presenting for a new oncology consultation for an oral lesion suspicious for cancer between March 2018 and March 2022, within the Department of Oral and Maxillofacial Surgery of the McGill University Health Center, were included. Data was collected on sociodemographic characteristics, oral cancer risk behaviors of study participants, oral cancer delays, tumor characteristics, and clinical management. A total of 190 patients were included, 91 patients from the pre-pandemic period and 99 from the pandemic period. The demographic characteristics of the patients in the two periods were comparable. There was no significant difference in the patient, professional, or treatment delay between the two periods. There was a non-significant increase in pathologic tumor size during the pandemic, but the pathologic staging and postoperative outcomes were comparable to those of the pre-pandemic cohort. The results indicate that emergent care pathways for oral cancer treatment were efficiently maintained despite the pandemic shutdown of services.

Evaluation of salivary endothelin-1 as a biomarker for oral cancer and precancer

CONTEXT

Oral cancer is highly prevalent in India. Lack of awareness and delay in diagnosis and treatment of patients with oral cancer leads to high mortality and poor survival of patients. Salivary endothelin-1 is proposed as a prospective biomarker for oral squamous cell carcinoma.

AIMS

Aim of the study was to evaluate salivary level of endothelin-1 in oral cancer and precancer as a biomarker.

SETTINGS AND DESIGN

We planned a case control study to evaluate salivary level of Endothelin-1 in oral cancer and precancer as a biomarker.

MATERIALS AND METHODS

A total of 72 subjects were taken in study out of which 24 cases were of histopathologically confirmed premalignat oral lesion (oral leukoplakia and oral submucous fibrosis), 24 cases were of histopathologically confirmed oral squamous cell carcinoma, and 24 cases of healthy age and gender matched controls without any addiction to tobacco in any form from a tertiary care hospital were taken. Saliva was collected from all following standard guidelines and estimation of salivary endothelin-1 was done by ELISA.

STATISTICAL ANALYSIS USED

SPSS software version 15.

RESULTS

Salivary endothelin-1 values of controls ranged between 0.09 and 1.88 pg/ml while that of premalignant cases ranged between 1.16 and 16.135 pg/ml and of SCC cases ranged between 2.567 and 22.98 pg/ml.

CONCLUSIONS

Salivary endothelin-1 is raised in oral squamous cell carcinoma compared to premalignant and controls therefore, shows capability to differentiate between premalignant lesion and oral cancer. So, it could be used as a biomarker for early diagnosis.

Correlation of PD-1 and PD-L1 expression in oral leukoplakia and oral squamous cell carcinoma: an immunohistochemical study

The programmed cell death protein (PD-1)/programmed cell death protein ligand (PD-L1) pathway and cytotoxic T lymphocyte antigen are the most important co-stimulatory molecules that play a key role in the negative regulation of T cells during carcinogenesis. We aimed to evaluate the immunohistochemical expression of PD-1 and PD-L1 in oral leukoplakia and squamous cell carcinoma compared with normal oral mucosa. Twenty-five cases of oral squamous cell carcinoma, oral leukoplakia and normal oral mucosa tissue specimens were immunohistochemically stained to assess PD-1 and PD-L1 expression. The PD-L1 positivity of subepithelial TAFs (p < 0.001) increased with increasing grades of oral leukoplakia. Pearson's correlation indicated a high positive correlation between the PD-L1 labelling index of epithelial tumour cells and the PD-1 labelling index of tumour infiltrating lymphocytes (p value: 0.005) in OSCC. A high positive correlation was noted between the H-score of PD-L1 positive tumour epithelial cells and the H-score of PD-1 positive tumour infiltrating lymphocytes in OSCC (p value: 0.001). PD-L1 positivity increased in dysplastic epithelial cells from premalignant lesions to malignancy. The sub-epithelial PD-L1 positive TAFs were higher in oral leukoplakia compared to OSCC inferring that PD-L1 positivity in TAFs decreased with malignant transformation. The PD-1 positivity in TILs was higher in oral leukoplakia than in OSCC.

Preliminary Evaluation Salivary Biomarkers in Patients with Oral Potentially Malignant Disorders (OPMD): A Case-Control Study

INTRODUCTION

Oral potentially malignant disorders (OPMD) are lesions associated with an increased risk of transformation (MT) into cancer.

OBJECTIVE

A study was made of the salivary levels of adenosine deaminase (ADA), ferritin (FRR) and total proteins (TP) in healthy individuals and in patients with oral potentially malignant disorders (OPMD), assessing the potential role of saliva as a diagnostic tool.

METHODS

A total of 91 subjects participated in the study, divided into two groups-59 patients with OPMD (oral leukoplakia or oral lichen planus) and 32 healthy controls-with measurements being made of salivary ADA, ferritin (FRR) and total proteins (TP).

RESULTS

There were no significant differences in salivary mean ADA between the OPMD group 0.85 ± 2.18 UI/I and the controls 0.71 ± 1.72 UI/I (p = 0.934), though the levels of both FRR mean OPMD, 12.66 ± 10.50 (µg/L), versus control, 7.19 ± 4.44 (p = 0.001), and TP, 23.41 ± 17, versus control, 14.15 ± 15.19, were significantly higher in the OPMD group (p = 0.001). Patients with oral lichen planus showed significant differences in terms of FRR (p = 0.009) and TP (p = 0.003). The ferritin in LPO with a cut-off point of 8.5C showed a sensitivity and specificity of 54.3% and 82.3, respectively. The area under the curve (AUC) was 0.69 (95% confidence interval (95% CI): 0.58-0.82; p = 0.003).

CONCLUSIONS

Ferritin and total proteins may constitute potential salivary biomarkers for oral lichen planus, though further studies are still needed in this field. In addition, saliva testing is a reliable and noninvasive diagnostic tool and appears to be a reliable strategy offering an interesting alternative for the screening of large populations.

Are medication-induced salivary changes the culprit of osteonecrosis of the jaw? A systematic review

Purpose

This systematic review was performed to assess the potential influence of medication-induced salivary changes on the development of medication-related osteonecrosis of the jaw (MRONJ).

Methods

An electronic search was conducted using PubMed, Web of Science, Cochrane, and Embase databases for articles published up to June 2023. A risk of bias assessment was performed according to the modified Newcastle-Ottawa Scale (NOS). Due to the heterogeneity of the selected studies in relation to the type of medications and outcomes evaluated, a meta-analysis could not be performed.

Results

The initial search revealed 765 studies. Only 10 articles were found to be eligible based on the inclusion criteria that reported on the impact of salivary changes on MRONJ following the administration of different medications. A total of 272 cases of MRONJ (35% women, 32% men, and 32% with no gender reported) with a mean age of 66 years at the time of diagnosis were included. Patients administered with bisphosphonates, steroids, chemotherapy, thalidomide, interferon, and hormone therapy had a significantly higher association between decreased salivary flow and MRONJ occurrence. In addition, bisphosphonates, denosumab, and other bone-modifying agents showed a significantly higher risk of developing MRONJ owing to the changes in salivary microbiome profiles, cytokine profiles, interleukins, hypotaurine, and binding proteins.

Conclusion

The reduction in salivary flow and changes in the concentration of salivary proteins were associated with the development of MRONJ. However, due to the availability of limited evidence, the findings of the review should be interpreted with caution.

Prospero review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022327645.

Review Insights on Salivary Proteomics Biomarkers in Oral Cancer Detection and Diagnosis

Early detection is crucial for the treatment and prognosis of oral cancer, a potentially lethal condition. Tumor markers are abnormal biological byproducts produced by malignant cells that may be found and analyzed in a variety of bodily fluids, including saliva. Early detection and appropriate treatment can increase cure rates to 80-90% and considerably improve quality of life by reducing the need for costly, incapacitating medicines. Salivary diagnostics has drawn the interest of many researchers and has been proven to be an effective tool for both medication monitoring and the diagnosis of several systemic diseases. Since researchers are now searching for biomarkers in saliva, an accessible bodily fluid, for noninvasive diagnosis of oral cancer, measuring tumor markers in saliva is an interesting alternative to blood testing for early identification, post-treatment monitoring, and monitoring high-risk lesions. New molecular markers for oral cancer detection, treatment, and prognosis have been found as a result of developments in the fields of molecular biology and salivary proteomics. The numerous salivary tumor biomarkers and how they relate to oral cancer and pre-cancer are covered in this article. We are optimistic that salivary protein biomarkers may one day be discovered for the clinical detection of oral cancer because of the rapid advancement of proteomic technology.

The Protective Role of Cranberries and Blueberries in Oral Cancer

BACKGROUND

Oral cancer has a high prevalence worldwide, and this disease is caused by genetic, immunological, and environmental factors. The main risk factors associated with oral cancer are smoking and alcohol.

RESULTS

There are various strategies to reduce risk factors, including prevention programs as well as the consumption of an adequate diet that includes phytochemical compounds derived from cranberries (Vaccinium macrocarpon A.) and blueberries (Vaccinium corymbosum L.); these compounds exhibit antitumor properties.

RESULTS

The main outcome of this review is as follows: the properties of phytochemicals derived from cranberries were evaluated for protection against risk factors associated with oral cancer.

CONCLUSIONS

The secondary metabolites of cranberries promote biological effects that provide protection against smoking and alcoholism. An alternative for the prevention of oral cancer can be the consumption of these cranberries and blueberries.

Significance of Fluorescent Spectroscopy in Screening Oral Potentially Malignant Disorders and Oral Cancer by Characterization of Salivary DNA Using Ethidium Bromide-A Comparative Study

Sangeetha RamamoorthyBackground  Optical diagnosis is one of the upcoming methods in screening and diagnosing oral cancer at the earlier stage. Currently, DNA-based diagnosis is used along with light-based imaging methods to diagnose oral cancer rapidly. Aim  The aim of this study was to discriminate oral cancer and oral potentially malignant disorders from normal patient with fluorescence spectroscopic characterization of salivary DNA using ethidium bromide dye. Materials and Methods  A total of 40 patients with average age of 20 to 60 years in both the genders were selected and divided into three groups. Group A included clinically proven cases of oral cancer, group B1 included clinically diagnosed cases of leukoplakia, group B2 included clinically diagnosed cases of oral submucous fibrosis, and group C included controls. Salivary DNA fluorescence spectrum obtained after adding ethidium bromide was analyzed using FluoroLog spectrophotometer at 480 nm wavelength. Results  The discriminant analysis of fluorescent emission of salivary DNA shows predictive accuracy of 90% between group C and group A, 95% between group C and group B1, and 65% observed between group C and group B2. Conclusion  From this study, screening of oral cancer can be done at the earliest with the help of fluorescence spectroscopic characterization of salivary DNA. This method can be done rapidly and noninvasively.

Mucins as Potential Biomarkers for Early Detection of Cancer

Early detection significantly correlates with improved survival in cancer patients. So far, a limited number of biomarkers have been validated to diagnose cancers at an early stage. Considering the leading cancer types that contribute to more than 50% of deaths in the USA, we discuss the ongoing endeavors toward early detection of lung, breast, ovarian, colon, prostate, liver, and pancreatic cancers to highlight the significance of mucin glycoproteins in cancer diagnosis. As mucin deregulation is one of the earliest events in most epithelial malignancies following oncogenic transformation, these high-molecular-weight glycoproteins are considered potential candidates for biomarker development. The diagnostic potential of mucins is mainly attributed to their deregulated expression, altered glycosylation, splicing, and ability to induce autoantibodies. Secretory and shed mucins are commonly detected in patients' sera, body fluids, and tumor biopsies. For instance, CA125, also called MUC16, is one of the biomarkers implemented for the diagnosis of ovarian cancer and is currently being investigated for other malignancies. Similarly, MUC5AC, a secretory mucin, is a potential biomarker for pancreatic cancer. Moreover, anti-mucin autoantibodies and mucin-packaged exosomes have opened new avenues of biomarker development for early cancer diagnosis. In this review, we discuss the diagnostic potential of mucins in epithelial cancers and provide evidence and a rationale for developing a mucin-based biomarker panel for early cancer detection.

Applications of Mass Spectrometry in Dentistry

Mass Spectrometry (MS) is one of the fastest-developing methods in analytical instrumentation. As a highly sensitive, universal detector, it can identify known and unknown compounds, which can indeed be found in a minimal concentration. This review aims to highlight the significant milestones in MS applications in dentistry during recent decades. MS can be applied in three different fields of dentistry: (1) in research of dental materials and chemical agents, (2) in laboratory analysis of biospecimens, and (3) as a real-time diagnostic tool in service of oral surgery and pathology. MS applications on materials and agents may focus on numerous aspects, such as their clinical behavior, possible toxicity, or antimicrobial properties. MS is also a valuable, non-invasive tool for biomarkers' detection in saliva and has found great application in -omics technologies as it achieves efficient structure-finding in metabolites. As metabolites are located beyond the central dogma, this technique can provide a complete understanding of cellular functions. Thus, it is possible to determine the biological profile in normal and pathological conditions, detect various oral or systematic diseases and conditions, and predict their course. Lastly, some promising advances concerning the surgical approach to potentially oral malignant or malignant disorders exist. This breakthrough method provides a comprehensive approach to dental materials research and biomarker discovery in dental and craniofacial tissues. The current availability of various 'OMIC' approaches paves the way for individualized dentistry and provides suggestions for clinical applications in the point-of-care hubs.

Advances in the Diagnosis, Monitoring, and Progression of Oral Cancer through Saliva: An Update

The early detection of cancer, and in particular oral cancer, has been a priority objective of study in recent years. Saliva has been proposed as an easy-to-obtain means of providing the necessary information to diagnose malignant lesions in the oral cavity, since it can be obtained very easily and completely noninvasively. There are a number of molecules, known as biomarkers, which may be involved in the malignant transformation of oral lesions, and which have different natures. The involvement of proteins (“proteomics”), metabolites (“metabolomics”), and even certain genes in the structural changes of altered tissue has been investigated in order to establish validated parameters for the early diagnosis of oral cancer. In addition, the development of new analytical assay methods that can reduce costs and obtain better results in terms of sensitivity and specificity has been a key point in recent research in this field. Even though there are numerous biomarkers with results showing high sensitivity and specificity, there is still a need for more studies, with a larger sample and with analytical methods that can constitute a real advance in time and cost. Although salivary biomarkers are a promising new diagnostic tool for oral cancer, for the moment they do not replace biopsy as the “gold standard”.

Association of dipeptidyl peptidase IV polymorphism with clinicopathological characters of oral cancer

OBJECTIVE

To evaluate the associations between dipeptidyl peptidase IV (DPP4) single nucleotide polymorphism (SNP) and clinicopathological characters of oral cancer.

METHODS

Four loci of DPP4 SNPs (rs7608798 A/G, rs3788979 C/T, rs2268889 T/C, and rs6741949 G/C) were genotyped by using the TaqMan allelic discrimination in 1238 oral cancers patients and 1197 non-cancer individuals.

RESULTS

The percentage of DPP4 SNP rs2268889 TC+CC was significantly higher in the oral cancer participants compared to the control group (odds ratio (OR): 1.178, 95% confidence interval (CI): 1.004-1.382, P = 0.045). Among 1676 smokers, DPP4 polymorphisms carriers with betel quid chewing were found to have a 8.785- to 10.903-fold risk to have oral cancer compared to DPP4 wild-type carriers without betel quid chewing. Similar trend was found in individuals with alcohol consumption. Moreover, the oral cancer individuals without cigarette smoking history with at least 1 varied C allele of DPP4 rs2268889 had a significantly higher percentage of large tumor size with the wild-type TT homozygote (P= 0.011).

CONCLUSIONS

The DPP4 SNP may correlate to the development of oral cancer in those with cigarette smoking and alcohol consumption. Besides, the DPP4 SNP rs2268889 could relate to worse clinical course of oral cancer in non-smokers.

Finding the combination of multiple biomarkers to diagnose oral squamous cell carcinoma - A data mining approach

Data mining has proven to be a reliable method to analyze and discover useful knowledge about various diseases, including cancer research. In particular, data mining and machine learning algorithms to study oral squamous cell carcinoma (OSCC), the most common form of oral cancer, is a new area of research. This malignant neoplasm can be studied using saliva samples. Saliva is an important biofluid that must be used to verify potential biomarkers associated with oral cancer. In this study, first, we provide an overview of OSSC diagnoses based on machine learning and salivary metabolites. To our knowledge, this is the first study to apply advanced data mining techniques to diagnose OSCC. Then, we give new results of classification and feature selection algorithms used to identify potential salivary biomarkers of OSCC. To accomplish this task, we used the filter feature selection random forest importance algorithm and a wrapper methodology to evaluate the importance of metabolites obtained from gas chromatography mass-spectrometry (GC-MS) in the context of differentiation of OSCC and the control group. Salivary samples (n = 68) were collected for the control group, and the OSCC group were from patients matched for gender, age, and smoking habit. The classification process occurred based on Random Forest (RF) classification algorithm along with 10-cross validation. The results showed that glucuronic acid, maleic acid, and batyl alcohol can classify the samples with an area under the curve (AUC) of 0.91 versus an AUC of 0.76 using all 51 metabolites analyzed. The methodology used in this study can assist healthcare professionals and be adopted to discover diagnostic biomarkers for other diseases.

Association of salivary Cathepsin B in different histological grades among patients presenting with oral squamous cell carcinoma

BACKGROUND

Oral cancer is considered a major public health problem due to its high mortality and morbidity rates. Survival rate of OSCC can be significantly improved by using non-invasive tool such as salivary biomarkers for detection of OSCC which is considered a promising approach. Cathepsin B is a lysosomal cysteine protease, present in abundant quantities in lysosome of cells, tissues and different biological fluids. Increased expression of Cathepsin B was observed in many malignancies including oral cancer. The present study was designed to determine the salivary levels of Cathepsin B in different histological grades of OSCC.

METHOD

In this study, total no. of 80 research participants were enrolled which were divided into four groups. Each group comprised 20 participants, group 1 comprised 20 patients of OSCC (well differentiated), group 2 comprised 20 patients of OSCC (moderately differentiated), group 3 comprised 20 patients of OSCC (poorly differentiated) and group 4 comprised 20 healthy controls. Saliva sample was collected from all the four study groups and salivary Cathepsin B levels were analyzed by ELISA sandwich technique in duplicate.

RESULTS

Salivary levels of Cathepsin B were significantly increased with p value (< 0.001) in patients of OSCC as compared to control group according to both histological grades and tumor size. Highest mean Cathepsin B levels in well differentiated OSCC followed by poorly differentiated OSCC and moderately differentiated OSCC were observed.

CONCLUSION

Results of the present study suggests that Cathepsin B has a great value as a salivary biomarker for diagnosis and monitoring of OSCC in different histological grades. This will further lead to increase survival rate and improve the prognosis of OSCC.

Evaluation of DNA methylation in promoter regions of hTERT, TWIST1, VIM and NID2 genes in Moroccan bladder cancer patients

Promoter hypermethylation have been reported to play a key role in bladder cancer development and progression. The aim of this study is to evaluate the methylation status of hTERT, TWIST1, VIM and NID2 genes in bladder cancer. The methylation status was evaluated using the Methylation-Specific PCR (MSP) approach on 70 tumour biopsies from Moroccan bladder cancer patients. Overall, methylation frequencies of hTERT, TWIST1, VIM and NID2 genes, were 90%, 85.71%, 67.14% and 67.14%, respectively. Hypermethylation of all studied genes was found in all pathological grades and stages of bladder cancer. Nevertheless, statistical analysis showed no significant association between promoter methylation of hTERT, TWIST1, VIM and NID2 genes and tumours stage/grade (p value >0.05). Moreover, we have investigated the association between the methylation pattern of selected genes and the treatment outcome in a sub-group of non-muscle-invasive bladder cancer cases (52/70). Hypermethylation of hTERT, TWIST1, VIM and NID2 was detected in 83.34%; 66.67%; 83.34% and 58.34% of recurrent cases, respectively, and in 80%; 80%; 80% and 60% of progressive cases, respectively. Statistical analysis highlighted a significant association between TWIST1 hypermethylation and tumour recurrence (p = 0.041<0.05). Our results indicate that hypermethylation of hTERT, TWIST1, VIM and NID2 genes is a frequent epigenetic event in bladder cancer and could be a promising therapeutic target to prevent bladder cancer progression and metastasis.

Recognizing the salivary panomics for the clinical application in oral potentially malignant disorders

Oral cancer arises as a result of multistep carcinogenic progress from precursor lesion to oral squamous cell carcinoma through collective mutational process occur in the stem cells of mucosal epithelium. The detection of such oral potentially malignant disorders (OPMDs)/cancer in subclinical level will greatly improve the prognosis of a patient. The highly specific and sensitive salivary biomarkers have functioned in detection, prediction, surveillance and therapeutic monitoring of the diseases of interest. The aim of the review is to appraise various salivary biomarkers for the clinical utility in OPMDs. An electronic web-supported search was performed via PubMed, ScienceDirect and Google Scholar search engine since the year 2015–2019. A total of 28 research articles were selected for the review after screening and assessment. The various genomic, transcriptomic, proteomic, metabolomic and miscellaneous markers were analyzed and their characteristics and clinical application in OPMD patients were discussed. miR-21, miR-31, miR-84, H3F3A mRNA + IL-8P, matrix metalloproteinase-9, chemerin, tumor necrosis factor-alpha, cytokeratin-10, ornithine + O-hydroxybenzoate + R5F, 8-hydroxy-2-deoxyguanosine, malondialdehyde, Vitamin E and Vitamin C are identified as potential markers for OPMD patients. Scientifically validated, reliable and economical clinical biomarkers in OPMDs would serve as evidence-based treatment from patient point of view. Further longitudinal studies are needed to verify the accuracy and validate the applicability of these diagnostic/prognostic markers. Saliva has been reported as a valuable noninvasive valuable tool in biomarker identification. Recent advancements in salivary biomarker identification techniques lead to various potential biomarkers with precise outcome. The utilization of these biomarkers for the clinical application in OPMDs depends on the feasibility and personal choice of the clinician.

Malignancies and Biosensors: A Focus on Oral Cancer Detection through Salivary Biomarkers

Oral cancer is among the deadliest types of malignancy due to the late stage at which it is usually diagnosed, leaving the patient with an average five-year survival rate of less than 50%. The booming field of biosensing and point of care diagnostics can, in this regard, play a major role in the early detection of oral cancer. Saliva is gaining interest as an alternative biofluid for non-invasive diagnostics, and many salivary biomarkers of oral cancer have been proposed. While these findings are promising for the application of salivaomics tools in routine practice, studies on larger cohorts are still needed for clinical validation. This review aims to summarize the most recent development in the field of biosensing related to the detection of salivary biomarkers commonly associated with oral cancer. An introduction to oral cancer diagnosis, prognosis and treatment is given to define the clinical problem clearly, then saliva as an alternative biofluid is presented, along with its advantages, disadvantages, and collection procedures. Finally, a brief paragraph on the most promising salivary biomarkers introduces the sensing technologies commonly exploited to detect oral cancer markers in saliva. Hence this review provides a comprehensive overview of both the clinical and technological advantages and challenges associated with oral cancer detection through salivary biomarkers.

Taxonomic and Functional Dysregulation in Salivary Microbiomes During Oral Carcinogenesis

Exploring microbial community compositions in humans with healthy versus diseased states is crucial to understand the microbe-host interplay associated with the disease progression. Although the relationship between oral cancer and microbiome was previously established, it remained controversial, and yet the ecological characteristics and their responses to oral carcinogenesis have not been well studied. Here, using the bacterial 16S rRNA gene amplicon sequencing along with the in silico function analysis by PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States 2), we systematically characterized the compositions and the ecological drivers of saliva microbiome in the cohorts of orally healthy, non-recurrent oral verrucous hyperplasia (a pre-cancer lesion), and oral verrucous hyperplasia–associated oral cancer at taxonomic and function levels, and compared them with the re-analysis of publicly available datasets. Diversity analyses showed that microbiome dysbiosis in saliva was significantly linked to oral health status. As oral health deteriorated, the number of core species declined, and metabolic pathways predicted by PICRUSt2 were dysregulated. Partitioned beta-diversity revealed an extremely high species turnover but low function turnover. Functional beta-diversity in saliva microbiome shifted from turnover to nestedness during oral carcinogenesis, which was not observed at taxonomic levels. Correspondingly, the quantitative analysis of stochasticity ratios showed that drivers of microbial composition and functional gene content of saliva microbiomes were primarily governed by the stochastic processes, yet the driver of functional gene content shifted toward deterministic processes as oral cancer developed. Re-analysis of publicly accessible datasets supported not only the distinctive family taxa of Veillonellaceae and Actinomycetaceae present in normal cohorts but also that Flavobacteriaceae and Peptostreptococcaceae as well as the dysregulated metabolic pathways of nucleotides, amino acids, fatty acids, and cell structure were related to oral cancer. Using predicted functional profiles to elucidate the correlations to the oral health status shows superior performance than using taxonomic data among different studies. These findings advance our understanding of the oral ecosystem in relation to oral carcinogenesis and provide a new direction to the development of microbiome-based tools to study the interplay of the oral microbiome, metabolites, and host health.

Supercritical fluid extraction-supercritical fluid chromatography of saliva: Single-quadrupole mass spectrometry monitoring of caffeine for gastric emptying studies†

Saliva is an attractive sampling matrix for measuring various endogenous and exogeneous substances but requires sample treatment prior to chromatographic analysis. Exploiting supercritical CO₂ for both extraction and chromatography simplifies sample preparation, reduces organic solvent consumption, and minimizes exposure to potentially infectious samples, but has not yet been applied to oral fluid. Here, we demonstrate the feasibility and benefits of online supercritical fluid extraction coupled to supercritical fluid chromatography and single-quadrupole mass spectrometry for monitoring the model salivary tracer caffeine. A comparison of ¹³ C- and ³² S-labeled internal standards with external standard calibration confirmed the superiority of stable isotope-labeled caffeine over nonanalogous internal standards. As proof of concept, the validated method was applied to saliva from a magnetic resonance imaging study of gastric emptying. After administration of 35 mg caffeine via ice capsule, salivary levels correlated with magnetic resonance imaging data, corroborating caffeine's usefulness as tracer of gastric emptying (R²  = 0.945). In contrast to off-line methods, online quantification required only minute amounts of organic solvents and a single manual operation prior to online bioanalysis of saliva, thus demonstrating the usefulness of CO₂ -based extraction and separation techniques for potentially infective biomatrices.

Liquid Biopsy: A Family of Possible Diagnostic Tools

Liquid biopsies could be considered an excellent diagnostic tool, in different physiological or pathological conditions. The possibility of using liquid biopsies for non-invasive clinical purposes is quite an old idea: indeed many years ago it was already being used in the field of non-invasive prenatal tests (NIPT) for autosomal fetal aneuploidy evaluation. In 1997 Lo et al. had identified fetal DNA in maternal plasma and serum, showing that about 10–15% of cfDNA in maternal plasma is derived from the placenta, and biologic fluid represents an important and non-invasive technique to evaluate state diseases and possible therapies. Nowadays, several body fluids, such as blood, urine, saliva and other patient samples, could be used as liquid biopsy for clinical non-invasive evaluation. These fluids contain numerous and various biomarkers and could be used for the evaluation of pathological and non-pathological conditions. In this review we will analyze the different types of liquid biopsy, their potential role in clinical diagnosis and the functional involvement of extracellular vesicles in these fluids as carriers.

Salivary Cytokines as Biomarkers for Oral Squamous Cell Carcinoma: A Systematic Review

The prognosis of patients with oral squamous carcinoma (OSCC) largely depends on the stage at diagnosis, the 5-year survival rate being approximately 30% for advanced tumors. Early diagnosis, including the detection of lesions at risk for malignant transformation, is crucial for limiting the need for extensive surgery and for improving disease-free survival. Saliva has gained popularity as a readily available source of biomarkers (including cytokines) useful for diagnosing specific oral and systemic conditions. Particularly, the close interaction between oral dysplastic/neoplastic cells and saliva makes such fluid an ideal candidate for the development of non-invasive and highly accurate diagnostic tests. The present review has been designed to answer the question: "Is there evidence to support the role of specific salivary cytokines in the diagnosis of OSCC?" We retrieved 27 observational studies satisfying the inclusion and exclusion criteria. Among the most frequent cytokines investigated as candidates for OSCC biomarkers, IL-6, IL-8, TNF-α are present at higher concentration in the saliva of OSCC patients than in healthy controls and may therefore serve as basis for the development of rapid tests for early diagnosis of oral cancer.

Markers associated with malignant transformation of oral lichen planus: A review article

Oral lichen planus (OLP) is one of the autoimmune diseases associated with chronic inflammation that involves several complications including the potential for malignant transformation into oral squamous cell carcinoma. Pathogenesis of OLP are yet to be fully comprehended however, it has been demonstrated that the epithelial cells in OLP lesions are affected by cytotoxic T lymphocytes leading to immunological reactions. Various factors are reported to act as diagnostic markers for predicting and monitoring the cancerous progression. Hence, in this review, we summarize and present the latest studies regarding the predictive markers associated with malignant potential of OLP.

A phase I study of a PARP1-targeted topical fluorophore for the detection of oral cancer

BACKGROUND

Visual inspection and biopsy is the current standard of care for oral cancer diagnosis, but is subject to misinterpretation and consequently to misdiagnosis. Topically applied PARPi-FL is a molecularly specific, fluorescent contrast-based approach that may fulfill the unmet need for a simple, in vivo, non-invasive, cost-effective, point-of-care method for the early diagnosis of oral cancer. Here, we present results from a phase I safety and feasibility study on fluorescent, topically applied PARPi-FL. Twelve patients with a histologically proven oral squamous cell carcinoma (OSCC) gargled a PARPi-FL solution for 60 s (15 mL, 100 nM, 250 nM, 500 nM, or 1000 nM), followed by gargling a clearing solution for 60 s. Fluorescence measurements of the lesion and surrounding oral mucosa were taken before PARPi-FL application, after PARPi-FL application, and after clearing. Blood pressure, oxygen levels, clinical chemistry, and CBC were obtained before and after tracer administration.

RESULTS

PARPi-FL was well-tolerated by all patients without any safety concerns. When analyzing the fluorescence signal, all malignant lesions showed a significant differential in contrast after administration of PARPi-FL, with the highest increase occurring at the highest dose level (1000 nM), where all patients had a tumor-to-margin fluorescence signal ratio of >3. A clearing step was essential to increase signal specificity, as it clears unbound PARPi-FL trapped in normal anatomical structures. PARPi-FL tumor cell specificity was confirmed by ex vivo tabletop confocal microscopy. We have demonstrated that the fluorescence signal arose from the nuclei of tumor cells, endorsing our macroscopic findings.

CONCLUSIONS

A PARPi-FL swish & spit solution is a rapid and non-invasive diagnostic tool that preferentially localizes fluorescent contrast to OSCC. This technique holds promise for the early detection of OSCC based on in vivo optical evaluation and targeted biopsy of suspicious lesions in the oral cavity.

TRIAL REGISTRATION

Clinicaltrials.gov -NCT03085147, registered on March 21st, 2017.

Estimation of salivary matrix metalloproteinases- 12 (MMP- 12) levels among patients presenting with oral submucous fibrosis and oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma is a global threat and accounts for approximately 90% of malignant oral lesions. The emergence of oral carcinoma is linked to precancerous lesions, which act as precursors of the disease. Matrix metalloproteinases appear to play a significant role in the pathogenesis of both precancerous conditions and oral malignancies due to their participation in remodeling of the extracellular matrix.

METHODOLOGY

This is an analytical study conducted at Dow University of Health Sciences, Pakistan. Unstimulated saliva samples were collected from healthy, oral submucous fibrosis and oral squamous cell carcinoma patients. The level of MMP-12 was estimated using enzyme-linked immunosorbent assay. One-way Analysis of variance was run to determine if MMP-12 levels differ between the three groups, which was preceded by post hoc Tuckey test. MMP-12 cut off values were determined using Receiver operating characteristic curve.

RESULTS

A significant difference in salivary MMP-12 expression was observed in OSF and OSCC (p < 0.001). The expression of salivary MMP-12 was higher in OSF and OSCC patients as compared to the healthy group (p < 0.001). The mean MMP-12 expression in OSCC appeared higher than in OSF cases (p < 0.05). MMP-12 value of [Formula: see text] 4.05 ng/ml and [Formula: see text] 4.20 ng/ml is predictive of OSF and OSCC respectively, with 100% sensitivity and specificity (p < 0.001).

CONCLUSION

Increased expression of MMP-12 appears as the healthy patient advances to OSF and OSCC. The study results also demonstrate higher MMP-12 expression in OSCC patients as compared to OSF. Therefore, the estimation of salivary MMP-12 serves as a valuable non-invasive early diagnostic tool in diagnosing oral submucous fibrosis and oral squamous cell carcinoma.

Recent advances in point-of-care diagnostics for oral cancer

Early-stage diagnosis is a crucial step in reducing the mortality rate in oral cancer cases. Point-of-care (POC) devices for oral cancer diagnosis hold great future potential in improving the survival rates as well as the quality of life of oral cancer patients. The conventional oral examination followed by needle biopsy and histopathological analysis have limited diagnostic accuracy. Besides, it involves patient discomfort and is not feasible in resource-limited settings. POC detection of biomarkers and diagnostic adjuncts has emerged as non- or minimally invasive tools for the diagnosis of oral cancer at an early stage. Various biosensors have been developed for the rapid detection of oral cancer biomarkers at the point-of-care. Several optical imaging methods have also been employed as adjuncts to detect alterations in oral tissue indicative of malignancy. This review summarizes the different POC platforms developed for the detection of oral cancer biomarkers, along with various POC imaging and cytological adjuncts that aid in oral cancer diagnosis, especially in low resource settings. Various immunosensors and nucleic acid biosensors developed to detect oral cancer biomarkers are summarized with examples. The different imaging methods used to detect oral tissue malignancy are also discussed herein. Additionally, the currently available commercial devices used as adjuncts in the POC detection of oral cancer are emphasized along with their characteristics. Finally, we discuss the limitations and challenges that persist in translating the developed POC techniques in the clinical settings for oral cancer diagnosis, along with future perspectives.

Salivary Immunoglobulin Gamma-3 Chain C Is a Promising Noninvasive Biomarker for Systemic Lupus Erythematosus

We aimed to characterize the salivary protein components and identify biomarkers in patients with systemic lupus erythematosus (SLE). A proteomic analysis using two-dimensional gel electrophoresis and mass spectrometry was performed to determine the alterations of salivary proteins between patients with SLE and healthy controls, and the concentrations of the candidate proteins were measured through Western blot analysis and the enzyme-linked immunosorbent assay. The 10 differentially expressed protein spots were immunoglobulin gamma-3 chain C region (IGHG3), immunoglobulin alpha-1 chain C region, protein S100A8, lactoferrin, leukemia-associated protein 7, and 8-oxoguanine DNA glycosylase. The patients with SLE exhibited enhanced salivary IGHG3 (3.9 ± 2.15 pg/mL) and lactoferrin (4.7 ± 1.8 pg/mL) levels compared to patients with rheumatoid arthritis (1.8 ± 1.01 pg/mL and 3.2 ± 1.6 pg/mL, respectively; p < 0.001 for both) or healthy controls (2.2 ± 1.64 pg/mL and 2.2 ± 1.7 pg/mL, respectively; p < 0.001 for both). The salivary IGHG3 levels correlated with the erythrocyte sedimentation rate (r = 0.26, p = 0.01), anti-double-stranded DNA (dsDNA) antibody levels (r = 0.25, p = 0.01), and nephritis (r = 0.28, p = 0.01). The proteomic analysis revealed that the salivary IGHG3 levels were associated with SLE and lupus disease activity, suggesting that salivary IGHG3 may be a promising noninvasive biomarker for SLE.

Clinical validation of 13-gene DNA methylation analysis in oral brushing samples for detection of oral carcinoma: Italian multicenter study

BACKGROUND

The aim of this Italian multicenter study was to evaluate the diagnostic performance of a minimally invasive method for the detection of oral squamous cell carcinoma (OSCC) based on 13-gene DNA methylation analysis in oral brushing samples.

METHODS

Oral brushing specimens were collected in 11 oral medicine centers across Italy. Twenty brushing specimens were collected by each center, 10 from patients with OSCC, and 10 from healthy volunteers. DNA methylation analysis was performed in blindness, and each sample was determined as positive or negative based on a predefined cutoff value.

RESULTS

DNA amplification failed in 4 of 220 (1.8%) samples. Of the specimens derived from patients with OSCC, 93.6% (103/110) were detected as positive, and 84.9% (90/106) of the samples from healthy volunteers were negative.

CONCLUSION

These data confirmed the diagnostic performance of our novel procedure in a large cohort of brushing specimens collected from 11 different centers and analyzed in blindness.

Oral Cancer and Precancer: A Narrative Review on the Relevance of Early Diagnosis

Oral cancer (OC) is an uncommon malignancy in Western countries, being one of the most common cancers in some high-risk areas of the world. It is a largely preventable cancer, since most of the different risk factors identified, such as tobacco use, alcohol consumption, and betel nut chewing, are behaviors that increase the likelihood of the disease. Given its high mortality, early diagnosis is of utmost importance. Prevention and the anticipation of diagnosis begin with identification of potentially malignant lesions of the oral mucosa and with local conditions promoting chronic inflammation. Therefore, every lesion must be recognized promptly and treated adequately. The clinical recognition and evaluation of oral mucosal lesions can detect up to 99% of oral cancers/premalignancies. As stated by the World Health Organization, any suspicious lesion that does not subside within two weeks from detection and removal of local causes of irritation must be biopsied. Surgical biopsy remains the gold standard for diagnosis of oral cancer. Adjunctive tools have been developed and studied to help clinicians in the diagnostic pathway, such as toluidine blue vital staining and autofluorescence imaging. In the near future other methods, i.e., identification of salivary markers of progression may help in reducing mortality due to oral cancer.

Autophagy-A Hidden but Important Actor on Oral Cancer Scene

The duration of denture use, oral hygiene, smoking and male sex were identified as risk factors for oral mucosal lesions. As it is well known, all the oral mucosal lesions associated with risk factors have an important degree of malignity. Chronic mechanical irritation can be another cause of oral cancer and it is produced by the constant action of a deleterious agent from the oral cavity. Autophagy represents a complex evolutionary conserved catabolic process in which cells self-digest intracellular organelles in order to regulate their normal turnover and remove the damaged ones with compromised function to further maintain homeostasis. Autophagy is modulated by mTOR kinase and indirectly by PI3K/AKT survival pathway. Due to its dual capacity to either induce cell death or promote cell survival, important evidence pointed that autophagy has a two-faced role in response to chemotherapy in cancer. In conclusion, understanding how to overcome cytoprotective autophagy and how to take advantage of autophagic cell death is critical in order to enhance the cancer cells sensitivity to particular therapeutic agents.

Salivary metabolomics for cancer detection

Introduction: Saliva is an ideal biofluid that can be collected in a noninvasive manner, enabling safe and frequent screening of various diseases. Recent studies have revealed that salivary metabolomics analysis has the potential to detect both oral and systemic cancers. Area covered: We reviewed the technical aspects, as well as applications, of salivary metabolomics for cancer detection. The topics include the effects of preconditioning and the method of sample collection, sample storage, processing, measurement, data analysis, and validation of the results. We also examined the rational relationship between salivary biomarkers and tumors distant from the oral cavity. A strategy to establish standard operating protocols for obtaining reproducible quantification data is also discussed Expert opinion: Salivary metabolomics reflects oral and systematic health status, which potently enables cancer detection. The sensitivity and specificity of each marker and their combinations have been well evaluated, but a validation study is required. Further, the standard operating protocol for each procedure should be established to obtain reproducible data before clinical usage.

One-year evaluation of a new restorative glass ionomer cement for the restoration of non-carious cervical lesions in patients with systemic diseases: a randomized, clinical trial

Objective

This randomized and clinical trial aimed to evaluate the performance of a new restorative Glass Ionomer Cement (GIC) for the restoration of non-carious cervical lesions (NCCLs) of patients with systemic diseases compared with a posterior resin composite after 12 months.

Methodology

134 restorations were placed at 30 patients presenting systemic diseases by a single clinician. NCCLs were allocated to two groups according to restorative system used: a conventional restorative GIC [Fuji Bulk (GC, Tokyo Japan) (FB)] and a posterior resin composite [G-ænial Posterior (GC, Tokyo Japan) (GP)] used with a universal adhesive using etch&rinse mode. All restorative procedures were conducted according to manufacturer’s instructions. Restorations were scored regarding retention, marginal discoloration, marginal adaptation, secondary caries, surface texture, and post-operative sensitivity using modified United States Public Health Service (USPHS) criteria after 1 week (baseline), 6, and 12 months. Descriptive statistics were performed using chi-square tests. Cochran Q and Mc Nemar’s tests were used to detect differences over time.

Results

After 12 months, recall rate was 93% and the rates of cumulative retention failure for FB and GP were 4.9% and 1.6% respectively. Both groups presented similar alpha rates for marginal adaptation (FB 86.2%, GP 95.5%) and marginal discoloration (FB 93.8%, GP 97%) at 6-month recall, but FB restorations showed higher bravo scores than GP restorations for marginal adaptation and marginal discoloration after 12 months (p<0.05). Regarding surface texture, 2 FB restorations (3.1%) were scored as bravo after 6 months. All restorations were scored as alpha for secondary caries and postoperative sensitivity after 12 months.

Conclusion

Although the posterior resin composite demonstrated clinically higher alpha scores than the conventional GIC for marginal adaptation and discoloration, both materials successfully restored NCCLs at patients with systematic disease after a year.

Clinical relevance

Due to its acceptable clinical results, the tested conventional restorative GIC can be used for the restoration of NCCLs of patients with systemic diseases.

Oral Neutrophils: Underestimated Players in Oral Cancer

The composition of the oral milieu reflects oral health. Saliva provides an environment for multiple microorganisms, and contains soluble factors and immune cells. Neutrophils, which rapidly react on the changes in the microenvironment, are a major immune cell population in saliva and thus may serve as a biomarker for oral pathologies. This review focuses on salivary neutrophils in the oral cavity, their phenotype changes in physiological and pathological conditions, as well as on factors regulating oral neutrophil amount, activation and functionality, with special emphasis on oral cancer and its risk factors.

[Diagnostic accuracy of salivary biomarkers for oral cancer and potentially malignant disorders: A systematic review protocol]

INTRODUCTION

Oral cancer has a 5-year survival rate of 50% because diagnosis is commonly performed at an advanced stage of the disease, so new diagnostic tools are needed. Nowadays, there is a vast number of publications suggesting the use of salivary biomarkers for oral cancer and potentially malignant disorders diagnosis, but their diagnostic accuracy is unclear. Thus, the goal of this systematic review is to evaluate the diagnostic accuracy of salivary biomarkers for oral cancer and potentially malignant disorders.

METHODS

This protocol is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P). We will include primary studies assessing the diagnostic accuracy of salivary biomarkers for oral cancer and potentially malignant disorders. Studies must report data about sensitivity and specificity; gold standard must be the histopathology diagnosis. We will search MEDLINE, EMBASE, the Cochrane Library, and gray literature. Two authors will independently select the studies and extract the data. The methodology quality of studies will be determined using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2).

EXPECTED RESULTS AND CONCLUSION

Our findings will provide information about the diagnostic accuracy of salivary biomarkers for oral cancer and potentially malignant disorders.

Salivary biomarkers for cancer diagnosis: a meta-analysis

Background: Saliva represents a promising non-invasive source of novel biomarkers for diagnosis and prognosis cancer. This meta-analysis evaluates the diagnostic value of salivary biomarkers for detection of malignant non-oral tumours to better define the value of saliva as an alternative liquid biopsy.Materials and methods: We performed a systematic review and meta-analysis. PubMed, Embase, LILACS and the Cochrane Library were searched to identify articles that examined the potential of salivary biomarkers for the diagnosis of malignant non-oral tumours. To assess the overall accuracy, we calculated the diagnostic odds ratio (DOR), area under hierarchical summary receiver operating characteristic (AUC) curve, sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) using a random- or fixed-effects model. Heterogeneity and publication bias were assessed. Statistical tests were two-sided.Results: One hundred fifty-five study units from 29 articles with 11,153 subjects were included. The pooled sensitivity, specificity, PLR, NLR, DOR and AUC were 0.76 (95% confidence intervals (CI), 0.74-0.77), 0.76 (95% CI, 0.75-0.77), 3.22 (95% CI, 2.92-3.55), 0.31 (95% CI, 0.28-0.34), 13.42 (95% CI, 12.28-15.96) and 0.85 (95% CI, 0.84-0.87), respectively.Conclusion: Salivary biomarkers may be potentially used for non-invasive diagnosis of malignant non-oral tumours.Key messagesThis meta-analysis evaluates the diagnostic value of salivary biomarkers for detection of malignant non-oral tumours to better define the role of saliva as an alternative liquid biopsy.Salivary biomarkers showed 85% accuracy for cancer distant to the oral cavity.Saliva represents a promising non-invasive source of novel biomarkers in cancer.

Evaluation of NID2 promoter methylation for screening of Oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is an aggressive human malignancy. Because of late diagnosis and recurrence of OSCC, the treatment of patients with OSCC is often ineffective. Thus, finding novel biomarkers of OSCC are essential. Here we derived a methylation marker by utilizing methylation microarray data and testing its capacity in cross-sectional study designed for OSCC detection and screening.

Methods

According to bioinformatics analysis of total of 27,578 cg sites, cg22881914 of Nidogen 2 (NID2) methylation was selected for evaluation. Next, we confirmed the methylation status by bisulfite sequencing from the microdissected OSCC cells in comparison with the microdissected oral epithelia. Subsequently, we developed a simple technique using real-time PCR with the specific probe to examine the ability for the detection of OSCC in the oral epithelial samples, which included 103 oral rinse and 82 oral swab samples.

Results

Based on the comparison of microdissected tissue, cg22881914 of NID2 was proved to be methylated in most OSCC cells but unmethylated in the normal oral epithelia. Furthermore, the methylated NID2-relied quantitative PCR approach has demonstrated that this marker assists in distinguishing among patients with OSCC from normal oral epithelia, smokers, and patients with oral lichen planus using the non-invasive oral rinse and swab samples.

Conclusions

Specific methylation at cg22881914 of NID2 of OSCC could be used as an important potential marker for detecting OSCC. Thus, to certify the utility of this marker, further studies with a larger sample size are needed.

Age and gender characteristics of the biochemical composition of saliva: Correlations with the composition of blood plasma

Background

Recently, the attention of researchers to the study of the properties of human saliva, as a material with unique properties and diagnostic capabilities, has increased.

Research objective

to study the connection of the biochemical composition of saliva and blood plasma in the norm, depending on gender and age.

Methods

107 volunteers took part in the study, including 46 female (37.2 ± 3.9 years old) and 61 male (36.1 ± 2.8 years old). In all samples of saliva and blood plasma, 16 biochemical parameters were determined, including mineral and protein composition, enzyme activity. Non-parametric statistical methods were used to process the data.

Results

It has been shown that it is difficult to establish an unambiguous relation between biochemical parameters of saliva and blood plasma. The calculation of the Spearman correlation coefficients showed that only 7 of the 16 parameters demonstrate the presence of a weak correlation between the content in saliva and plasma.

Conclusion

In general, the determination of the composition of saliva may have an independent diagnostic value; in this case, drawing a parallel with the composition of serum and blood plasma is not advisable. Nevertheless, the use of saliva in clinical laboratory diagnostics is associated with the need to establish criteria for the norm and pathology for each biochemical parameter.

Salivary Redox Biomarkers in Selected Neurodegenerative Diseases

Neurodegenerative diseases (NDDs), such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are disorders, which cause irreversible and progressive deterioration of the central nervous system. The pathophysiology of NDDs is still not fully explained; nevertheless, oxidative stress is considered as a critical mediator of cerebral degeneration, brain inflammation, as well as neuronal apoptosis. Therefore, it is not surprising that redox biomarkers are increasingly used in the diagnosis of neurodegenerative diseases. As saliva is a very easy to obtain bioliquid, it seems promising to use this biomaterial in the diagnosis of NDDs. Saliva collection is easy, cheap, stress-free, and non-infectious, and it does not require the help of a specialised medical personnel. Additionally, the concentrations of many salivary redox biomarkers correlate with their content in blood serum as well as the degree of disease progression, which makes them non-invasive indicators of NDDs. This paper reviews the latest knowledge concerning the use of salivary redox biomarkers in the diagnosis and prognosis of selected neurodegenerative diseases.

Autophagy modulators for the treatment of oral and esophageal squamous cell carcinomas

Oral squamous cell carcinomas (OSCC) and esophageal squamous cell carcinomas (ESCC) exhibit a survival rate of less than 60% and 40%, respectively. Late-stage diagnosis and lack of effective treatment strategies make both OSCC and ESCC a significant health burden. Autophagy, a lysosome-dependent catabolic process, involves the degradation of intracellular components to maintain cell homeostasis. Targeting autophagy has been highlighted as a feasible therapeutic strategy with clinical utility in cancer treatment, although its associated regulatory mechanisms remain elusive. The detection of relevant biomarkers in biological fluids has been anticipated to facilitate early diagnosis and/or prognosis for these tumors. In this context, recent studies have indicated the presence of specific proteins and small RNAs, detectable in circulating plasma and serum, as biomarkers. Interestingly, the interplay between biomarkers (eg, exosomal microRNAs) and autophagic processes could be exploited in the quest for targeted and more effective therapies for OSCC and ESCC. In this review, we give an overview of the available biomarkers and innovative targeted therapeutic strategies, including the application of autophagy modulators in OSCC and ESCC. Additionally, we provide a viewpoint on the state of the art and on future therapeutic perspectives combining the early detection of relevant biomarkers with drug discovery for the treatment of OSCC and ESCC.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Morphology of Dried Drop Patterns of Saliva from a Healthy Individual Depending on the Dynamics of Its Surface Tension

Background: The study of processes in the drying drops of biological fluids (dried drop patterns) and the method of dynamic surface tensiometry can be attributed to integral methods of assessing the state of the organism. Research objective: to establish the relationship between the type of crystallization patterns and the surface tension of human saliva in normal conditions. Methods: 100 volunteers (40 males, 60 females) that were aged 30–59 participated in the study. In all saliva samples, the parameters of dynamic tensiometry, types of crystallization patterns and 11 biochemical parameters were determined. Results: No statistically significant differences in the saliva crystallization patterns were observed, depending on the age and gender characteristics of the volunteers. A negative correlation of the area of the crystallization zone and the surface tension of saliva is shown. When considering the crystallization patterns, their considerable variability was noted; on this basis, the entire studied sample was divided into four clusters by surface tension. Conclusion: In general, the crystallization patterns that are inside the selected groups remain quite heterogeneous. This increases the likelihood of making an incorrect diagnosis when using visual methods to evaluate the crystallization patterns, which significantly limits the use of such diagnostic methods in clinical practice.

Expression of programmed cell death-ligand 1 in oral squamous cell carcinoma and oral leukoplakia is associated with disease progress and CD8+ tumor-infiltrating lymphocytes

OBJECTIVE

In recent years, monoclonal antibodies targeting programmed cell death-ligand 1 (PD-L1) have become a promising cancer immunotherapy. However, the role of PD-L1 in oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMDs), including oral leukoplakia (OLK), remains controversial. The aim of the present study was to investigate the expression level of PD-L1 in OSCC and OPMDs, and examine its relationship with CD8 expression and different clinicopathological features.

METHOD

Expression of PD-L1 and CD8 were conducted in 41 OSCC, 21 OLK, and 25 normal mucosa samples by immunohistochemistry. Then, the density of PD-L1 expression was measured, and its correlation with CD8 expression and different clinicopathological features was analyzed.

RESULTS

PD-L1 protein was detected in 97.6% of OSCC, 61.9% of OLK, and 0% of normal tissues. PD-L1 was highly expressed in human OSCC tissue (P < 0.0001), when compared to both OLK and control tissues. PD-L1 positivity was significantly associated with CD8 density (P < 0.0001, r = 0.8491). The PD-L1 high expression OSCC group displayed a trend for improved overall survival (OS) and disease-free survival (DFS) compared to the low expression group, although the differences were not significant. Moreover, the expression level of PD-L1 in OSCC was positively correlated with the pathological grade (P < 0.0001), but it was independent of age, gender, smoking, drinking, tumor size, lymph node status, or recurrence (P > 0.05). Also, there was a significant upregulation of PD-L1 expression observed in the OLK group compared to the control group (P < 0.0001). PD-L1 positivity in OLK patients was associated with gender and smoking habits (P < 0.05), but it did not correlate with age, drinking, or dysplasia (P > 0.05).

CONCLUSION

The upregulation of PD-L1 may be associated with disease progress and CD8+ tumor-infiltrating lymphocytes in oral premalignant and malignant lesions.