Saliva diagnostics - Current views and directions

Heterogeneity in benign and malignant salivary gland tumors

Advanced proteomics tools have identified the role of proteins in cancer biology, highlighting the importance of these molecules for biomarker discovery and providing valuable insights into cancer diagnosis, prognosis, and targeted therapy. Proteome analysis of tissue using high-throughput proteomics techniques has identified proteins associated with recurrence and malignant transformation in benign tumors, and protein profiling of fine needle aspiration has revealed potential biomarkers for distinguishing malignant salivary gland tumors from benign ones. In addition, proteomics studies have identified distinct protein expression patterns in mesenchymal stem cells derived from malignant salivary gland tumors, suggesting a potential role for proteins in adverse behavior and/or targeted therapy. To provide a comprehensive knowledge of salivary gland tumors, this review will first provide a brief description of the molecular and cellular alterations in common benign and malignant salivary gland tumors and then describe the proteomics studies by concentration on different biological sources including serum/plasma, saliva, tumor tissues and related derivatives (e.g. mesenchymal stem cells, tumor cells, tumor established cell lines, and fine needle aspiration), and introduce potential targets for diagnosis, prognosis, and cancer therapy.

Recent Advancements and Applications of Nanosensors in Oral Health: Revolutionizing Diagnosis and Treatment

Advances in the field of nanomaterials are laying the foundation for the fabrication of nanosensors that are sensitive, selective, specific, cost-effective, biocompatible, and versatile. Being highly sensitive and selective, nanosensors are crucial in detecting small quantities of analytes and early diagnosis of diseases. These devices, operating on the nanoscale, detect signals, such as physical, chemical, optical, electrochemical, or biological, and then transduce them into a readable form. They show great promise for real-time, point-of-care, and home-based applications in health care. With the integration of wireless technology, these nanosensors, specifically biosensors, can potentially revolutionize therapeutic techniques. These advancements particularly impact the oral cavity, the primary entry point for various bodily substances. Nanosensors can transform oral and dental health practices, enabling timely disease diagnosis and precise drug delivery. This review examines the recent advancements in nanobiosensors, exploring their applications in various oral health conditions while discussing their benefits and potential limitations.

Both aerosol and primer dimer breakdown for straightforward genotyping based on an integrated immunochromatographic biosensor

Straightforward genotyping can provide timely diagnostic information for diseases prevention and treatment. Taking advantages of speediness and convenience, although numerous genotyping strategies combined loop-mediated isothermal amplification (LAMP) and lateral flow have been reported to satisfy the demand of point-of-care test, the false positive result caused by aerosol and primer dimer as an innate conflict seriously limits their practical application. In this study, both aerosol and primer dimer as extrinsic and intrinsic inducements respectively are first broken through at one stroke based on an integrated immunochromatographic biosensor. By introducing digoxigenin labeled dUTP into LAMP, not only the amplicon can be analyzed through naked eye, but also the aerosol contamination can be eliminated thoroughly by uracil DNA glycosylase ignoring the open vessel. Primer dimer, the significant drawback in lateral flow-based strategies, has been overcome due to the bio-labeled deoxyribonucleotide and oligonucleotide cannot couple for signal generation even under the high primer concentration. Instead of colloidal gold, the gold magnetic nanoparticle is synthesized and assembled into this biosensor as a nanoprobe, which enables the result to be quantified by the magnetic signal for subjective bias elimination. The polymorphism of C677T in methylenetetrahydrofolate reductase, a crucial genetic code related to folate metabolism, is genotyped using saliva as noninvasive specimen dispense with DNA purification. Only 1 ng genomic DNA can provide accurate result within 25 min by a simple heater, which proves the potential of this biosensor to facilitate precision medicine.

Loss of tricellular tight junction tricellulin leads to hyposalivation in Sjögren's syndrome

Tricellulin, a key tricellular tight junction (TJ) protein, is essential for maintaining the barrier integrity of acinar epithelia against macromolecular passage in salivary glands. This study aims to explore the role and regulatory mechanism of tricellulin in the development of salivary gland hypofunction in Sjögren's syndrome (SS). Employing a multifaceted approach involving patient biopsies, non-obese diabetic (NOD) mice as a SS model, salivary gland acinar cell-specific tricellulin conditional knockout (TricCKO) mice, and IFN-γ-stimulated salivary gland epithelial cells, we investigated the role of tricellulin in SS-related hyposalivation. Our data revealed diminished levels of tricellulin in salivary glands of SS patients. Similarly, NOD mice displayed a reduction in tricellulin expression from the onset of the disease, concomitant with hyposecretion and an increase in salivary albumin content. Consistent with these findings, TricCKO mice exhibited both hyposecretion and leakage of macromolecular tracers when compared to control animals. Mechanistically, the JAK/STAT1/miR-145 axis was identified as mediating the IFN-γ-induced downregulation of tricellulin. Treatment with AT1001, a TJ sealer, ameliorated epithelial barrier dysfunction, restored tricellulin expression, and consequently alleviated hyposalivation in NOD mice. Importantly, treatment with miR-145 antagomir to specifically recover the expression of tricellulin in NOD mice significantly alleviated hyposalivation and macromolecular leakage. Collectively, we identified that tricellulin deficiency in salivary glands contributed to hyposalivation in SS. Our findings highlight tricellulin as a potential therapeutic target for hyposecretion, particularly in the context of reinforcing epithelial barrier function through preventing leakage of macromolecules in salivary glands.

All-in-one microfluidic immunosensing device for rapid and end-to-end determination of salivary biomarkers of cardiovascular diseases

Routine screening for cardiovascular diseases (CVDs) through point-of-care assays for at-home or community-based testing of salivary biomarkers can significantly improve patient outcomes. However, its translatability has been hindered by a dearth of biosensing devices that streamline assay procedures for rapid biomarker quantitation. To address this challenge through end-to-end engineering, we developed an in-house, all-in-one microfluidic immunosensing device that integrates on-chip vibration-enhanced incubation, magnetic-assisted separation using immune magnetic bead probes, and colorimetric readout via absorbance measurements. This device enables probe preparation and one-pot immunoassay procedures on a reusable microfluidic chip. By engaging the vibrator with the reaction chamber, the vibration-enhanced incubation module significantly accelerates immune complex formation, drastically reducing the sample-to-answer timeline of approximately 1 h required for room temperature enzyme-linked immunosorbent assay (ELISA) to just under 15 min. We showcase the utility of the device with an on-demand assay for a biomarker panel comprising C-reactive protein (CRP), interleukin 6 (IL-6), and procalcitonin (PCT). The device achieved a linear detection range of 1.75-28 ng mL-1 for CRP and 1.56-100 ng mL-1 for IL-6 and PCT with an R2 > 0.98 for all three biomarkers. The limits of detection were 0.295, 0.400, and 0.947 ng mL-1, respectively. Results from real saliva samples were consistent with standard ELISA (R2 = 0.952). This fully integrated, modular immunosensing device opens up opportunities for household CVD screening and could be adapted for rapid, affordable multiplexed biosensing for other major chronic diseases at the point of care.

Multiplexed detection of respiratory virus RNA using optical pH sensors and injection-molded centrifugal microfluidics

The application is demonstrated of injection-molded centrifugal microfluidic chips with integrated optical pH sensors for multiplexed detection of respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A, and influenza B RNA. The optical pH sensors generated sensitive fluorescent readouts from diagnostic reverse transcription loop-mediated isothermal amplification (RT-LAMP) reactions; limits of detection for influenzas A and B, and SARS-CoV-2 of 89, 245, and 38 RNA copies per reaction, respectively, were attained. Results were obtainable within 44 min for SARS-CoV-2 and influenza A, and 48 min for influenza B. We implemented a data processing strategy based on numerical derivatives of the fluorescence curves that allowed for reliable, quantitative thresholds for deciding reaction outcomes and enabled 100% specificity. This work demonstrates the utility of optical pH sensors and injection-molded centrifugal microfluidics for multiplexed infectious disease diagnostics with point-of-care applications.

Impact of Ramadan Intermittent Fasting on Salivary pH, Flow Rate, and Electrolyte Levels in Healthy Adult Men

This before-and-after design study, which was conducted during Ramadan 2023, aimed to compare salivary flow rate (SFR), potential hydrogen (pH), and electrolyte concentrations before Ramadan (BR), at the end of Ramadan (ER), and after Ramadan (AR). Men aged 20 to 30 years who were fasting during Ramadan were recruited from the University of Monastir (Tunisia). Unstimulated saliva was collected over a 5-minute period between 10 and 11 a.m. at BR, ER, and AR. After recording the SFR, the pH was measured immediately using a pH meter. Concentrations of several salivary electrolytes (e.g., calcium, potassium, sodium, chloride, and phosphate) were determined using inductively coupled plasma-optical emission spectroscopy. Twenty-seven participants completed all three sessions. Ramadan intermittent fasting (RIF) caused significant changes only in calcium levels and pH. The mean (M)±standard deviation (SD) salivary calcium concentration decreased during ER compared to BR and AR (0.10 ± 0.08 vs. 0.21 ± 0.18 [p = .041] vs. 0.22 ± 0.20 [p = .026], respectively). The M±SD salivary pH increased during ER compared to BR (6.88 ± 0.23 vs. 6.69 ± 0.35 [p = .049], respectively). To conclude, RIF decreased salivary calcium, increased salivary pH, and did not significantly affect potassium, sodium, chloride, or phosphate. The pH change, although statistically significant, was clinically insignificant, as values remained normal. The lack of reference values for salivary calcium limits assessment of its clinical impact. There is a need for further research on the effects of RIF on saliva secretion.

Technical considerations regarding saliva sample collection to achieve comparable protein identification and detection via one- and two-dimensional gel electrophoresis among humans

Background and aims

Recently, demands towards identifying various molecules in support of stress detection and potential clinical utilization are dramatically increasing. Moreover, the accuracy with which researchers quantify these informative molecules is now far more improved when compared to the past. As RNA or protein markers are conventionally detected via repeated invasive procedures from blood, it is critical to develop secure technologies to obtain the desired information via less stressful methodologies, such as saliva collection. Moreover, for superb interpretation, it became equally significant to obtain the information from the same exact specimen. RNA is easily degradable, thus it is paramount to supplement the samples with protective agents, such as RNAlater, to achieve accurate quantitative results.

Methods

In our research we investigated whether and how this commonly applied RNA protection procedure influences protein and peptide separation of the human saliva via quantitative two-dimensional protein electrophoresis.

Results

Our results revealed, in contrary to previously published data regarding plasma, the addition of RNAlater to saliva samples negatively influences isoelectric focusing and protein detection. We equally found the application oftentimes employed referred to as selective precipitation and reduction-alkylation, partially rescued separation, however, with a significant loss in protein yield and quality when compared to untreated samples.

Conclusion

Our results suggest collection of human saliva for biomarker identification must be performed with extreme diligence. We propose application of RNAlater should be avoided and snap freezing of the collected saliva is recommended when joint protein and RNA quantification is the ultimate goal.

Saliva in Balancing Oral and Systemic Health, Oral Cancer, and Beyond: A Narrative Review

Saliva plays a multifaceted role in oral health and systemic well-being. It supports digestion, protects oral tissues, maintains a healthy oral microbiome, and facilitates wound healing. Additionally, saliva serves as a diagnostic tool that reflects systemic health and disease/therapeutic states. Furthermore, although saliva shows a protective effect against oral cancer development, once tumor formation occurs, it may be involved in tumor progression and metastasis via exosomes and microRNAs. This review discusses the essential role of saliva; its relationship with the development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC); liquid biopsy tools for early diagnosis and monitoring of HNSCC; and the potential of exosomes as therapeutic agents.

Evaluation of Thermal Liquid Biopsy Analysis of Saliva and Blood Plasma Specimens as a Novel Diagnostic Modality in Head and Neck Cancer

BACKGROUND

Over the past decade, saliva-based liquid biopsies have emerged as promising tools for the early diagnosis, prognosis, and monitoring of cancer, particularly in high-risk populations. However, challenges persist because of low concentrations and variable modifications of biomarkers linked to tumor development when compared to normal salivary components.

METHODS

This study explores the application of differential scanning calorimetry (DSC)-based thermal liquid biopsy (TLB) for analyzing saliva and blood plasma samples from head and neck cancer (HNC) patients.

RESULTS

Our research identified an effective saliva processing method via high-speed centrifugation and ultrafiltration, resulting in reliable TLB data. Notably, we recorded unique TLB profiles for saliva from 48 HNC patients and 21 controls, revealing distinct differences in thermal transition features that corresponded to salivary protein denaturation. These results indicated the potential of saliva TLB profiles in differentiating healthy individuals from HNC patients and identifying tumor characteristics. In contrast, TLB profiles for blood plasma samples exhibited smaller differences between HNC patients and had less utility for differentiation within HNC.

CONCLUSIONS

Our findings support the feasibility of saliva-based TLB for HNC diagnostics, with further refinement in sample collection and the incorporation of additional patient variables anticipated to enhance accuracy, ultimately advancing non-invasive diagnostic strategies for HNC detection and monitoring.

Dysregulation of saliva and fecal microbiota as novel biomarkers of colorectal cancer

The aim of this study was to investigate the biomarkers of salivary and fecal microbiota in Colorectal cancer (CRC). Initially, the study scrutinized the microbial community composition disparities among groups. Utilizing Lasso analysis, it sifted through operational taxonomic units (OTUs) to pinpoint distinctive features. Subsequently, by intersecting feature OTUs across groups, it curated a set of core-shared OTUs and devised a corresponding network. Concluding with functional enrichment analysis, the research delved into the divergent biological functions of these microbial communities within the studied groups. Analysis revealed higher bacterial diversity in saliva compared to feces, with distinct differences at both phylum and genus levels. Feces primarily contained Firmicutes, while saliva was dominated by Bacteroidetes and Proteobacteria. Notably, Escherichia-Shigella and Fusobacterium in feces and Streptococcus in saliva showed increasing abundance from average to adenoma to colorectal cancer. Specific dominant flora was identified within and between groups, including CRC and adenomas across different stages. Seventeen core shared OTUs were identified, and networks of shared OTUs were constructed for each group. Functional enrichment analysis highlighted distinct microbial community functions among the groups. This study's findings on characteristic OTUs in saliva and fecal samples offer valuable insights for distinguishing between healthy individuals, adenoma patients, and those with colorectal cancer. This study identified distinctive OTUs in saliva and feces to distinguish between healthy individuals, adenoma patients, and those with CRC, offering a valuable diagnostic reference.

Leveraging Saliva for Insights into Head and Neck Cancer

Head and neck cancer (HNC) represents a heterogeneous group of malignancies with increasing global incidence and notable mortality. Early detection is essential for improving survival rates and minimizing recurrence; however, existing diagnostic methods are often invasive and complex. There is a need for noninvasive and more effective approaches for early detection and real-time monitoring of HNC. Saliva contains various biomolecules that may serve as indicators of HNC. As a result, saliva-based biomarkers have emerged as a transformative approach in the diagnosis and treatment of HNC due to their ease of collection, non-invasiveness, and potential to provide details about biomolecular changes associated with cancer progression. This narrative review synthesizes the current literature on the potential of saliva as a noninvasive diagnostic tool for HNC. It highlights various biomarkers found in saliva, including cell-free DNA, RNA, proteins, and metabolites, and explores emerging technologies in saliva detection that could transform the future of HNC management. Continued research efforts and larger-scale validation studies are essential to fully realize the potential of saliva-based biopsy and help pinpoint notable biomarkers to improve patient outcomes and reduce mortality associated with HNC worldwide.

NCI workshop on ctDNA in cancer treatment and clinical care

Detection of cell-free circulating tumor DNA (ctDNA) from solid tumors is a fast-evolving field with significant potential for improving patient treatment outcomes. The spectrum of applications for ctDNA assays is broad and includes very diverse intended uses that will require different strategies to demonstrate utility. On September 14-15, 2023, the National Cancer Institute held an in-person workshop in Rockville, MD titled "ctDNA in Cancer Treatment and Clinical Care." The goal of the workshop was to examine what is currently known and what needs to be determined for various ctDNA liquid biopsy use cases related to treatment and management of patients with solid tumors and to explore how the community can best assess the value of ctDNA assays and technology. Additionally, new approaches were presented that may show promise in the future. The information exchanged in this workshop will provide the community with a better understanding of this field and its potential to affect and benefit decision-making in the treatment of patients with solid tumors.

Salivary Metabolomics in Patients with Long COVID-19 Infection

Background: Long COVID-19 has been characterized by the presence of symptoms lasting longer than 4 weeks after the acute infection. The pathophysiology of clinical manifestations still lacks knowledge. Objective: The objective of this paper was to evaluate metabolite abundance in the saliva of long COVID patients 60 days after hospital discharge. Methods: A convenience sample was composed of 30 post-discharge patients with long COVID and seven non-COVID-19 controls. All COVID-19 patients were evaluated by demographic characteristics, spirometry, 6 min walk test (6mWT), Saint George Respiratory Questionnaire (SGRQ), and body composition. Metabolomics was performed on saliva. Results: The long COVID-19 patients were 60.4 ± 14.3 years-old, and 66% male. Their lean body mass was 30.7 ± 7.3 kg and fat mass, 34.4 ± 13.7 kg. Spirometry evaluation showed forced vital capacity (FVC) of 3.84 ± 0.97 L with 96.0 ± 14.0% of the predicted value, and forced expiratory volume in the first second (FEV1) of 3.11 ± 0.83 L with 98.0 ± 16.0 of the predicted value. The long COVID-19 patients had reduced maximal inspiratory (90.1 ± 31.6 cmH2O) and maximal expiratory (97.3 ± 31.0 cmH2O) pressures. SGRQ showed domain symptoms of 32.3 ± 15.2, domain activities of 41.9 ± 25.6, and domain impact 13.7 ± 11.4, with a mean of 24.3 ± 14.9%. Physical capacity measured by distance covered in the 6mWT was 418.2 ± 130 m with a 73.3% (22.3-98.1) predictive value. The control group consisted of 44.1 ± 10.7-year-old men with a body mass index of 26.5 ± 1.66 Kg/m2. Metabolomics revealed 19 differentially expressed metabolites; expression was lower in 16 metabolites, and 2 metabolites were absent in the COVID-19 patients compared to controls. Calenduloside G methyl ester (p = 0.03), Gly Pro Lys (p = 0.0001), and creatine (p = 0.0001) expressions were lower in patients than controls. Conclusions: Long COVID-19 patients present less abundance of calenduloside G methyl ester, Gly Pro Lys, and creatine in saliva than healthy controls. Lower creatine abundance may be related to reduced physical capacity and fatigue.

Validating proteomic biomarkers in saliva: distinguishing between health and periodontal diseases

INTRODUCTION

Periodontitis is a chronic inflammatory disease characterized by progressive soft tissue and alveolar bone loss due to interactions between microbial dental plaque and the host response. Despite extensive research on biomarkers from saliva or gingival crevicular fluid (GCF) for diagnosing periodontitis, clinical and radiological parameters remain the primary diagnostic tools.

AREAS COVERED

This review discusses the ongoing research into salivary biomarkers for periodontitis diagnosis, emphasizing the need for reliable biomarkers to differentiate between periodontal health and disease. Salivary biomarker research has gained momentum with advancements in proteomic technologies, enabling noninvasive sample collection and revealing potential candidate biomarkers.

EXPERT OPINION

Proteomic research since the early 2000s has identified promising biomarkers and provided insights into the pathogenesis of periodontitis. Bioinformatic analysis of proteomic data elucidates the underlying biological mechanisms. This review summarizes key findings and highlights common potential biomarkers identified through proteomic research in periodontology.

Saliva metabolomics: concepts and applications in oral disorders

OBJECTIVES

The purpose of this review was to present the basic concepts of metabolomics methodology and the use of saliva for diagnostic, prognostic, and predictive strategies.

MATERIAL AND METHODS

This review followed the focus in: "saliva metabolomics" and "oral diseases". The authors searched studies on PubMed database. The inclusion criteria were original studies and reviews that assessed metabolomics techniques. A descriptive analysis was performed considering the study design, approach system, clinical steps, and tools for the determination of profile or biomarkers metabolites, and the advantages and disadvantages.

RESULTS

Metabolomic analyses use a combination of analytical instrumentation and informatic tools to provide information on metabolite characteristics. In this review we described different technologies applied and the advantages and limitations of each technique. Furthermore, in the literature search, we retrieved 25 studies that investigated saliva metabolites in oral diseases: 8 studies used targeted analysis and 17 untargeted metabolomics approaches. Most studies included patients with periodontal diseases, oral squamous cell carcinoma, and Sjögren Syndrome. The most frequently reported metabolites were glycine, leucine, phenylalanine, dipeptides, linoleic acid, arachidonic acid, tyrosine, choline, taurine, lactate, valine, and proline.

CONCLUSIONS

Metabolomics analysis has emerged as a powerful tool for tumor diagnosis and to enhance tumor classification, including salivary gland tumors (SGTs). It also holds promise for developing personalized treatment plans and defining more precise prognostic categories.

CLINICAL RELEVANCE

Metabolomics is the most functional and comprehensive technique for monitoring and understanding gene functions and identifying the biochemical state of an organism in response to genetic and environmental changes.

Comparative Bibliometric Analysis of Established and Emerging Databases on Salivary Biomarkers for Early Oral Cancer Diagnosis

BACKGROUND

Salivary biomarkers play an important role in the preventive strategy for oral cancer detection at an early stage. The aim of this study was to carry out a comparative quantitative analysis of the research material on the topic in one established database, Scopus and another emerging database, Dimensions.

METHOD

An electronic search was performed in Scopus and Dimensions in April 2024 with the search subjects "Saliva," "Biomarkers," "Diagnosis," and "Oral Cancer." The retrieved data were analyzed using Biblioshiny for RStudio and MS Excel.

RESULT

The search yielded 229 and 158 documents in Scopus and Dimensions, respectively. The data were studied to understand the coverage, concentration, and diversion of research articles. The analysis revealed high singularity index for Scopus and low overlap percentage between the two databases. Scopus was found to have higher citation count per article, however, the citation correlation between Scopus and Dimensions was found to be strong. Author productivity was found to be low in both the databases.

CONCLUSION

Scopus and Dimensions vary in their scope, volume of data, and coverage policies. Both the databases have complimentary coverage on salivary biomarkers for oral cancer diagnosis. However, Scopus has a greater number of articles, sources, and citations resulting in better coverage of the topic.

Diagnostic and therapeutic potentials of extracellular vesicles for primary Sjögren's Syndrome: A review

Primary Sjögren syndrome (pSS) is a chronic autoimmune disease mainly affecting salivary and lacrimal glands. The current pSS biomarkers, serum autoantibodies, are negative in many pSS patients diagnosed with histopathology changes, indicating the need of novel biomarkers. The current therapies of pSS are merely short-term symptomatic relief and can't provide effective long-term remedy. Extracellular vehicles (EVs) are nano-sized lipid bilayer-delimited particles spontaneously released by almost all types of cells and carrying various bioactive molecules to mediate inter-cellular communications. Recent studies found that EVs from salivary gland epithelial cells and immune cells play essential roles in pSS pathogenesis. Correspondingly, EVs and their cargos in plasma and saliva are promising candidate biomarkers for pSS diagnosis. Moreover, EVs from mesenchymal stem cells have shown promises to improve pSS treatment by modulating immune responses. This review summarizes recent findings in roles of EVs in pSS pathogenesis, diagnosis, and treatment of pSS, as well as related challenges and future research directions.

Salivary exosomal microRNA profile as biomonitoring tool for diagnosis and prognosis of patients with head and neck squamous cell carcinoma: a systematic review

OBJECTIVE

Exosomes are extracellular vesicles found in saliva and other body fluids. These vesicles range in size from 30 to 150 nm and play a crucial role in intercellular communication, transporting different biomolecules, actively targeting cells. These vesicles regulate both physiological and pathological processes within recipient cells. MicroRNAs (miRs) are transported within exosomes and are delivered to target cells where they influence signaling pathways, taking on a crucial regulatory role in oncogenesis; for example, they are implicated in progression and infiltration of various cancers, such as head and neck squamous cell carcinoma (HNSCC).

MATERIAL AND METHODS

A systematic literature search based on specific keywords, according to the PRISMA guidelines, was carried out on PubMed, Web of Science, Scopus, and Google Scholar. Only original articles were selected during this review. The risk of bias was assessed by QUADAS-2.

RESULTS

At the end of the selection process 9 articles were included. In these studies, 41 miRs showed differential expression between healthy subjects and patient with HNSCC. The techniques varied among studies for the extraction and analysis of exosomal miRs. We presented also salivary exosomal miRs pathways, to give insights about pathogenetic mechanisms.

CONCLUSIONS

Exosomal microRNA are promising biomarkers for HNSCC detection. MiR-10b-5p, miR-486-5p, miR-24-3p, miR-412-3p, and miR-512-3p are the most promising markers applicable to diagnostics, while miR-1307-5p and miR-519c-3p resulted overexpressed and correlated to worse survival outcomes.

Salivary Molecular Spectroscopy with Machine Learning Algorithms for a Diagnostic Triage for Amelogenesis Imperfecta

Amelogenesis imperfecta (AI) is a genetic disease characterized by poor formation of tooth enamel. AI occurs due to mutations, especially in AMEL, ENAM, KLK4, MMP20, and FAM83H, associated with changes in matrix proteins, matrix proteases, cell-matrix adhesion proteins, and transport proteins of enamel. Due to the wide variety of phenotypes, the diagnosis of AI is complex, requiring a genetic test to characterize it better. Thus, there is a demand for developing low-cost, noninvasive, and accurate platforms for AI diagnostics. This case-control pilot study aimed to test salivary vibrational modes obtained in attenuated total reflection fourier-transformed infrared (ATR-FTIR) together with machine learning algorithms: linear discriminant analysis (LDA), random forest, and support vector machine (SVM) could be used to discriminate AI from control subjects due to changes in salivary components. The best-performing SVM algorithm discriminates AI better than matched-control subjects with a sensitivity of 100%, specificity of 79%, and accuracy of 88%. The five main vibrational modes with higher feature importance in the Shapley Additive Explanations (SHAP) were 1010 cm-1, 1013 cm-1, 1002 cm-1, 1004 cm-1, and 1011 cm-1 in these best-performing SVM algorithms, suggesting these vibrational modes as a pre-validated salivary infrared spectral area as a potential biomarker for AI screening. In summary, ATR-FTIR spectroscopy and machine learning algorithms can be used on saliva samples to discriminate AI and are further explored as a screening tool.

Biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is among the most common neurodegenerative disorders. AD is characterized by deposition of neurofibrillary tangles and amyloid plaques, leading to associated secondary pathologies, progressive neurodegeneration, and eventually death. Currently used diagnostics are largely image-based, lack accuracy and do not detect early disease, ie, prior to onset of symptoms, thus limiting treatment options and outcomes. Although biomarkers such as amyloid-β and tau protein in cerebrospinal fluid have gained much attention, these are generally limited to disease progression. Unfortunately, identification of biomarkers for early and accurate diagnosis remains a challenge. As such, body fluids such as sweat, serum, saliva, mucosa, tears, and urine are under investigation as alternative sources for biomarkers that can aid in early disease detection. This review focuses on biomarkers identified through proteomics in various biofluids and their potential for early and accurate diagnosis of AD.

Proteomics-based host-specific biomarkers for tuberculosis: The future of TB diagnosis

Tuberculosis (TB) is an infectious disease that remains one of the major global public health concerns. Early detection of Active Pulmonary TB is therefore of utmost importance for controlling lethality and disease spreading. Currently available TB diagnostics can be broadly categorized into microscopy, culture-based, and molecular approaches, all of which come with compromised sensitivity, limited efficacy, and high expenses. Hence, rapid, sensitive, and affordable diagnostic methods for TB is the current prerequisite for disease management. This review summarizes the proteomics investigations for host-specific biomarkers from serum, sputum, saliva, and urine samples of TB patients, along with patients having comorbidity. Thorough data mining from available literature led us to conclude that the host-specific proteins involved in immunity and defense, metabolic regulation, cellular adhesion, and motility, inflammatory responses, and tissue remodelling have shown significant deregulation upon Mycobacterium tuberculosis (Mtb) infection. Notably, the immunoregulatory protein orosomucoid (ORM) was up-regulated in active TB compared to non-TB individuals, as observed in multiple studies from diverse sample types. Mannose receptor C type 2 (MRC2) was identified as an upregulated, treatment response biomarker in two independent serum proteomics investigations. Thorough mechanistic investigation on these candidate proteins would be fascinating to dig into potential drug targets and customized therapeutics for TB patients, along with their diagnostic potentials.

Expression profile of diagnostic genes in oral submucous fibrosis

Oral Submucous Fibrosis (OSMF) is a chronic precancerous disorder of the oral mucosa caused by chewing of areca nut and its other variants. Chewing of areca nuts leads to dysregulated expression of specific genes, leading to various premalignant or malignant disorders. This study aimed to determine the differential expression of the diagnostic genes (MYH6, TNNT3, MYL1, and TPM2) in healthy controls and OSMF patients using saliva and tissue samples, determining the histopathological grade of the clinical samples. A total of 20 patients were included in the study and were divided into two groups: Group I consisted of 10 healthy patients (control group) and Group II consisted of 10 OSMF patients. Unstimulated whole saliva samples were collected from both groups, and the tissue samples were divided into two parts: one for RT-qPCR analysis and the other for histopathological assay. The expression profile of genes concerning OSMF saliva and tissue samples was significantly upregulated compared to the healthy control, and all the clinical samples of the study were categorized into histopathological grade 1. The findings of this study concluded that these genes can be referred to as diagnostic genes for OSMF in early and very early clinical samples, and saliva can be used as a promising diagnostic tool for early OSMF studies.

The salivary microbiome as a diagnostic biomarker of periodontitis: a 16S multi-batch study before and after the removal of batch effects

Introduction

Microbiome-based clinical applications that improve diagnosis related to oral health are of great interest to precision dentistry. Predictive studies on the salivary microbiome are scarce and of low methodological quality (low sample sizes, lack of biological heterogeneity, and absence of a validation process). None of them evaluates the impact of confounding factors as batch effects (BEs). This is the first 16S multi-batch study to analyze the salivary microbiome at the amplicon sequence variant (ASV) level in terms of differential abundance and machine learning models. This is done in periodontally healthy and periodontitis patients before and after removing BEs.

Methods

Saliva was collected from 124 patients (50 healthy, 74 periodontitis) in our setting. Sequencing of the V3-V4 16S rRNA gene region was performed in Illumina MiSeq. In parallel, searches were conducted on four databases to identify previous Illumina V3-V4 sequencing studies on the salivary microbiome. Investigations that met predefined criteria were included in the analysis, and the own and external sequences were processed using the same bioinformatics protocol. The statistical analysis was performed in the R-Bioconductor environment.

Results

The elimination of BEs reduced the number of ASVs with differential abundance between the groups by approximately one-third (Before=265; After=190). Before removing BEs, the model constructed using all study samples (796) comprised 16 ASVs (0.16%) and had an area under the curve (AUC) of 0.944, sensitivity of 90.73%, and specificity of 87.16%. The model built using two-thirds of the specimens (training=531) comprised 35 ASVs (0.36%) and had an AUC of 0.955, sensitivity of 86.54%, and specificity of 90.06% after being validated in the remaining one-third (test=265). After removing BEs, the models required more ASVs (all samples=200-2.03%; training=100-1.01%) to obtain slightly lower AUC (all=0.935; test=0.947), lower sensitivity (all=81.79%; test=78.85%), and similar specificity (all=91.51%; test=90.68%).

Conclusions

The removal of BEs controls false positive ASVs in the differential abundance analysis. However, their elimination implies a significantly larger number of predictor taxa to achieve optimal performance, creating less robust classifiers. As all the provided models can accurately discriminate health from periodontitis, implying good/excellent sensitivities/specificities, the salivary microbiome demonstrates potential clinical applicability as a precision diagnostic tool for periodontitis.

Exploring Salivary Iodine Concentration as a Biomarker for Iodine Status and Thyroid Nodules in Females From Different Water Iodine Areas: a Cross-sectional Study

BACKGROUND

It is unclear whether salivary iodine concentration (SIC) can assess iodine status in females from different water iodine regions.

OBJECTIVES

Through a cross-sectional study, we explored the feasibility of SIC as a biomarker to assess iodine status in females and develop optimal cutoff values.

METHODS

A total of 1991 females were analyzed in this cross-sectional study from the coastal iodine-deficient areas (CIDAs), inland iodine-deficient areas (IIDAs), iodine-adequate areas (IAAs), iodine-excess areas (IEAs), and iodine extra-high areas (IEHAs). SIC, spot urine iodine concentration (SUIC), and daily total iodine intake (TII) were assessed, and ultrasonography was performed in all subjects.

RESULTS

There was a positive correlation between SIC and SUIC (r = 0.67; 95% CI: 0.64, 0.69; P < 0.001), and TII (r = 0.47; 95% CI: 0.43, 0.50; P < 0.001). The prevalence of thyroid nodules (TN) showed an upward trend with SIC increasing (Z = -2.83; P-trend = 0.005). The area under the receiver-operating characteristic (ROC) curve for SIC to assess iodine deficiency was 0.62 (95% CI: 0.60, 0.65; P < 0.001) and 0.75 (95% CI: 0.73, 0.77; P < 0.001) for iodine excess. The cutoff values were as follows: SIC < 93.32 μg/L, iodine deficiency; 93.32-224.60 μg/L, iodine adequacy; and >224.60 μg/L, iodine excess. When SIC > 224.60 μg/L, the odds ratio (OR) for UIC > 300 μg/L, excessive TII, and the prevalence of TN were 6.44, 3.68, and 1.27 (95% CI: 4.98, 8.31; 2.83, 4.79; and 1.02, 1.56, respectively; P < 0.05); when SIC < 93.32 μg/L, the OR for UIC < 100 μg/L and insufficient TII were 2.34 and 1.94 (95% CI: 1.73, 3.14 and 1.33, 2.83, respectively; P < 0.05).

CONCLUSIONS

Using SIC as a biomarker, females in CIDA exhibited mild iodine deficiency, those in IIDA and IAA demonstrated moderate iodine deficiency, and those in IEA and IEHA exhibited an excess of iodine, consistent with SUIC to assess iodine status. SIC can be used as a good biomarker to evaluate the iodine status in population.

Fatty Acid Desaturase Bmdesat5, Suppressed in the Salivary Glands by Domestication, is Involved in Regulation of Food Intake in Silkworms

Understanding the evolutionary genetics of food intake regulation in domesticated animals has relevance to evolutionary biology, animal improvement, and obesity treatment. Here, we observed that the fatty acid desaturase gene (Bmdesat5), which regulates food intake, is suppressed in domesticated silkworms, but expressed in the salivary glands of the wild silkworm Bombyx mandarina. The content of its catalytic product, cis-vaccenic acid, was related to the expression levels of Bmdesat5 in the salivary glands of domesticated and wild silkworm strains. These two strains also showed significant differences in food intake. Using orally administering cis-vaccenic acid and transgenic-mediated overexpression, we verified that cis-vaccenic acid functions as a satiation signal, regulating food intake and growth in silkworms. Selection analysis showed that Bmdesat5 experienced selection, especially in the potential promoter, 5'-untranslated, and intron regions. This study highlights the importance of the decrement of satiety in silkworm domestication and provides new insights into the potential involvement of salivary glands in the regulation of satiety in animals, by acting as a supplement to gut-brain nutrient signaling.

Parallel detection of multiple biomarkers in a point-of-care-competent device for the prediction of exacerbations in chronic inflammatory lung disease

Sudden aggravations of chronic inflammatory airway diseases are difficult-to-foresee life-threatening episodes for which advanced prognosis-systems are highly desirable. Here we present an experimental chip-based fluidic system designed for the rapid and sensitive measurement of biomarkers prognostic for potentially imminent asthma or COPD exacerbations. As model biomarkers we chose three cytokines (interleukin-6, interleukin-8, tumor necrosis factor alpha), the bacterial infection marker C-reactive protein and the bacterial pathogen Streptococcus pneumoniae-all relevant factors in exacerbation episodes. Assay protocols established in laboratory environments were adapted to 3D-printed fluidic devices with emphasis on short processing times, low reagent consumption and a low limit of detection in order to enable the fluidic system to be used in point-of-care settings. The final device demonstrator was validated with patient sample material for its capability to detect endogenous as well as exogenous biomarkers in parallel.

Salivary metabolites are promising noninvasive biomarkers of drug-induced liver injury

BACKGROUND

Drug-induced liver injury (DILI) is one of the most common adverse events of medication use, and its incidence is increasing. However, early detection of DILI is a crucial challenge due to a lack of biomarkers and noninvasive tests.

AIM

To identify salivary metabolic biomarkers of DILI for the future development of noninvasive diagnostic tools.

METHODS

Saliva samples from 31 DILI patients and 35 healthy controls (HCs) were subjected to untargeted metabolomics using ultrahigh-pressure liquid chromatography coupled with tandem mass spectrometry. Subsequent analyses, including partial least squares-discriminant analysis modeling, t tests and weighted metabolite coexpression network analysis (WMCNA), were conducted to identify key differentially expressed metabolites (DEMs) and metabolite sets. Furthermore, we utilized least absolute shrinkage and selection operato and random fores analyses for biomarker prediction. The use of each metabolite and metabolite set to detect DILI was evaluated with area under the receiver operating characteristic curves.

RESULTS

We found 247 differentially expressed salivary metabolites between the DILI group and the HC group. Using WMCNA, we identified a set of 8 DEMs closely related to liver injury for further prediction testing. Interestingly, the distinct separation of DILI patients and HCs was achieved with five metabolites, namely, 12-hydroxydodecanoic acid, 3-hydroxydecanoic acid, tetradecanedioic acid, hypoxanthine, and inosine (area under the curve: 0.733-1).

CONCLUSION

Salivary metabolomics revealed previously unreported metabolic alterations and diagnostic biomarkers in the saliva of DILI patients. Our study may provide a potentially feasible and noninvasive diagnostic method for DILI, but further validation is needed.

Applicability of Gene Expression in Saliva as an Alternative to Blood for Biodosimetry and Prediction of Radiation-induced Health Effects

As the great majority of gene expression (GE) biodosimetry studies have been performed using blood as the preferred source of tissue, searching for simple and less-invasive sampling methods is important when considering biodosimetry approaches. Knowing that whole saliva contains an ultrafiltrate of blood and white blood cells, it is expected that the findings in blood can also be found in saliva. This human in vivo study aims to examine radiation-induced GE changes in saliva for biodosimetry purposes and to predict radiation-induced disease, which is yet poorly characterized. Furthermore, we examined whether transcriptional biomarkers in blood can also be found equivalently in saliva. Saliva and blood samples were collected in parallel from radiotherapy (RT) treated patients who suffered from head and neck cancer (n = 8) undergoing fractioned partial-body irradiations (1.8 Gy/fraction and 50-70 Gy total dose). Samples were taken 12-24 h before first irradiation and ideally 24 and 48 h, as well as 5 weeks after radiotherapy onset. Due to the low quality and quantity of isolated RNA samples from one patient, they had to be excluded from further analysis, leaving a total of 24 saliva and 24 blood samples from 7 patients eligible for analysis. Using qRT-PCR, 18S rRNA and 16S rRNA (the ratio being a surrogate for the relative human RNA/bacterial burden), four housekeeping genes and nine mRNAs previously identified as radiation responsive in blood-based studies were detected. Significant GE associations with absorbed dose were found for five genes and after the 2nd radiotherapy fraction, shown by, e.g., the increase of CDKN1A (2.0 fold, P = 0.017) and FDXR (1.9 fold increased, P = 0.002). After the 25th radiotherapy fraction, however, all four genes (FDXR, DDB2, POU2AF1, WNT3) predicting ARS (acute radiation syndrome) severity, as well as further genes (including CCNG1 [median-fold change (FC) = 0.3, P = 0.013], and GADD45A (median-FC = 0.3, P = 0.031)) appeared significantly downregulated (FC = 0.3, P = 0.01-0.03). A significant association of CCNG1, POU2AF1, HPRT1, and WNT3 (P = 0.006-0.04) with acute or late radiotoxicity could be shown before the onset of these clinical outcomes. In an established set of four genes predicting acute health effects in blood, the response in saliva samples was similar to the expected up- (FDXR, DDB2) or downregulation (POU2AF1, WNT3) in blood for up to 71% of the measurements. Comparing GE responses (PHPT1, CCNG1, CDKN1A, GADD45A, SESN1) in saliva and blood samples, there was a significant linear association between saliva and blood response of CDKN1A (R2 = 0.60, P = 0.0004). However, the GE pattern of other genes differed between saliva and blood. In summary, the current human in vivo study, (I) reveals significant radiation-induced GE associations of five transcriptional biomarkers in salivary samples, (II) suggests genes predicting diverse clinical outcomes such as acute and late radiotoxicity as well as ARS severity, and (III) supports the view that blood-based GE response can be reflected in saliva samples, indicating that saliva is a "mirror of the body" for certain but not all genes and, thus, studies for each gene of interest in blood are required for saliva.

Identification of Inflammatory Mediators in Saliva Samples From Hospitalized Newborns: Potential Biomarkers?

Saliva measurements serve as a noninvasive tool for clinically monitoring newborns (NB) and children, a vulnerable population with promising potential for both research and clinical practice. Saliva acts as a repository for various inflammatory biomarkers involved in diverse biological functions. Particularly for children, it offers numerous advantages when compared to plasma and urine sampling. Nevertheless, there is a significant knowledge gap regarding detectable levels of cytokines in the saliva of newborns and children, as well as studies aiming to assess the relationship of this content with physiological and pathological processes.

OBJECTIVES

To characterize the levels of 11 inflammatory mediators (IFNg, IL1b, IL2, IL4, IL6, IL8, IL10, IL12, IL17, TNF, and VEGF) in saliva samples from NB on the first and second day of hospitalization in the Neonatal Intensive Care Unit (NICU).

METHOD

Exploratory study, descriptive, nested within a primary clinical, observational, and prospective study, conducted in the NICU of a public hospital in São Paulo, Brazil. Demographic data and vital signs were recorded in the clinical records of 90 NB, and five saliva samples from 5 NB were collected between the first and second day of life (D1-D2) at approximately 8-hr intervals (8-9 am, 4-5 pm, and 11-12 pm). Saliva samples were used for the measurement of 11 cytokines (IFNg, IL1b, IL2, IL4, IL6, IL8, IL10, IL12, IL17, TNF, and VEGF).

RESULTS

Five NBs participated in this exploratory study, and the vital signs showed variability from the first (D1) to the second day (D2) of hospitalization, variability similar to that of the total population of the primary study. The presence and levels of the 11 cytokines were detected in the saliva samples, as well as a statistical correlation between 10 cytokines (IFNg, IL1b, IL2, IL4, IL6, IL10, IL12, IL17, TNF, and VEGF) and vital signs.

CONCLUSIONS

The novelty of measuring inflammatory mediators in saliva samples from hospitalized NBs in the NICU is highlighted, providing support and new perspectives for the development of clinical and experimental research and an opportunity for developing and implementing new salivary biomarkers in different population segments.

Advances in research on biomarkers associated with acute myocardial infarction: A review

Acute myocardial infarction (AMI), the most severe cardiovascular event in clinical settings, imposes a significant burden with its annual increase in morbidity and mortality rates. However, it is noteworthy that mortality due to AMI in developed countries has experienced a decline, largely attributable to the advancements in medical interventions such as percutaneous coronary intervention. This trend highlights the importance of accurate diagnosis and effective treatment to preserve the myocardium at risk and improve patient outcomes. Conventional biomarkers such as myoglobin, creatine kinase isoenzymes, and troponin have been instrumental in the diagnosis of AMI. However, recent years have witnessed the emergence of new biomarkers demonstrating the potential to further enhance the accuracy of AMI diagnosis. This literature review focuses on the recent advancements in biomarker research in the context of AMI diagnosis.

Host-microbiome associations in saliva predict COVID-19 severity

Established evidence indicates that oral microbiota plays a crucial role in modulating host immune responses to viral infection. Following severe acute respiratory syndrome coronavirus 2, there are coordinated microbiome and inflammatory responses within the mucosal and systemic compartments that are unknown. The specific roles the oral microbiota and inflammatory cytokines play in the pathogenesis of coronavirus disease 2019 (COVID-19) are yet to be explored. Here, we evaluated the relationships between the salivary microbiome and host parameters in different groups of COVID-19 severity based on their oxygen requirement. Saliva and blood samples (n = 80) were collected from COVID-19 and from noninfected individuals. We characterized the oral microbiomes using 16S ribosomal RNA gene sequencing and evaluated saliva and serum cytokines and chemokines using multiplex analysis. Alpha diversity of the salivary microbial community was negatively associated with COVID-19 severity, while diversity increased with health. Integrated cytokine evaluations of saliva and serum showed that the oral host response was distinct from the systemic response. The hierarchical classification of COVID-19 status and respiratory severity using multiple modalities separately (i.e. microbiome, salivary cytokines, and systemic cytokines) and simultaneously (i.e. multimodal perturbation analyses) revealed that the microbiome perturbation analysis was the most informative for predicting COVID-19 status and severity, followed by the multimodal. Our findings suggest that oral microbiome and salivary cytokines may be predictive of COVID-19 status and severity, whereas atypical local mucosal immune suppression and systemic hyperinflammation provide new cues to understand the pathogenesis in immunologically compromised populations.

Evaluating and optimizing Acid-pH and Direct Lysis RNA extraction for SARS-CoV-2 RNA detection in whole saliva

COVID-19 has been a global public health and economic challenge. Screening for the SARS-CoV-2 virus has been a key part of disease mitigation while the world continues to move forward, and lessons learned will benefit disease detection beyond COVID-19. Saliva specimen collection offers a less invasive, time- and cost-effective alternative to standard nasopharyngeal swabs. We optimized two different methods of saliva sample processing for RT-qPCR testing. Two methods were optimized to provide two cost-efficient ways to do testing for a minimum of four samples by pooling in a 2.0 mL tube and decrease the need for more highly trained personnel. Acid-pH-based RNA extraction method can be done without the need for expensive kits. Direct Lysis is a quick one-step reaction that can be applied quickly. Our optimized Acid-pH and Direct Lysis protocols are reliable and reproducible, detecting the beta-2 microglobulin (B2M) mRNA in saliva as an internal control from 97 to 96.7% of samples, respectively. The cycle threshold (Ct) values for B2M were significantly higher in the Direct Lysis protocol than in the Acid-pH protocol. The limit of detection for N1 gene was higher in Direct Lysis at ≤ 5 copies/μL than Acid-pH. Saliva samples collected over the course of several days from two COVID-positive individuals demonstrated Ct values for N1 that were consistently higher from Direct Lysis compared to Acid-pH. Collectively, this work supports that each of these techniques can be used to screen for SARS-CoV-2 in saliva for a cost-effective screening platform.

Endotypes of Paediatric Cough-Do They Exist and Finding New Techniques to Improve Clinical Outcomes

Chronic cough is a common symptom of many childhood lung conditions. Given the phenotypic heterogeneity of chronic cough, better characterization through endotyping is required to provide diagnostic certainty, precision therapies and to identify pathobiological mechanisms. This review summarizes recent endotype discoveries in airway diseases, particularly in relation to children, and describes the multi-omic approaches that are required to define endotypes. Potential biospecimens that may contribute to endotype and biomarker discoveries are also discussed. Identifying endotypes of chronic cough can likely provide personalized medicine and contribute to improved clinical outcomes for children.

Pre-Analytical Factors Affecting Extracellular DNA in Saliva

Salivary DNA is widely used for genetic analyses because of its easy collection. However, its extracellular fraction in particular, similar to the extracellular DNA (ecDNA) in plasma, could be a promising biomarker for oral or systemic diseases. In contrast to genetics, the quantity of salivary ecDNA is of importance and can be affected by the pre-analytical processing of samples, but the details are not known. The aim of our study was to analyze the effects of centrifugation and freezing of saliva on the concentration of ecDNA in saliva. Fifteen healthy volunteers, free of any known systemic or oral diseases, were asked to collect unstimulated saliva samples. Aliquots were centrifuged at 1600× g and frozen or directly processed. The fresh or thawed cell-free saliva samples underwent subsequent centrifugation at 16,000× g. The supernatants were used for DNA isolation and quantification using fluorometry and real-time PCR. While freezing had minimal effects on the salivary ecDNA concentration, another centrifugation step decreased ecDNA considerably in both fresh and frozen samples (by 97.8% and 98.4%, respectively). This was mirrored in the quantitative PCR targeting a nuclear (decrease by 93.5%) and mitochondrial (decrease by 97.7%) ecDNA sequence. In conclusion, in this first study focusing on the technical aspects of salivary ecDNA quantitation, we show that, regardless of its subcellular origin, the concentration of ecDNA in saliva is mainly affected by additional centrifugation and not by the freezing of centrifuged cell-free saliva samples. This suggests that most salivary ecDNA likely is associated with cell debris and apoptotic bodies. Which fraction is affected by a particular disease should be the focus of further targeted studies.

Targeted Phosphoproteomics of Human Saliva Extracellular Vesicles via Multiple Reaction Monitoring Cubed (MRM3)

Oral squamous cell carcinoma (OSCC) has become a global health problem due to its increasing incidence and high mortality rate. Early intervention through monitoring of the diagnostic biomarker levels during OSCC treatment is critical. Extracellular vesicles (EVs) are emerging surrogates in intercellular communication through transporting biomolecule cargo and have recently been identified as a potential source of biomarkers such as phosphoproteins for many diseases. Here, we developed a multiple reaction monitoring cubed (MRM3) method coupled with a novel sample preparation strategy, extracellular vesicles to phosphoproteins (EVTOP), to quantify phosphoproteins using a minimal amount of saliva (50 μL) samples from OSCC patients with high specificity and sensitivity. Our results established differential patterns in the phosphopeptide content of healthy, presurgery, and postsurgery OSCC patient groups. Notably, we discovered significantly increased salivary phosphorylated alpha-amylase (AMY) in the postsurgery group compared to the presurgery group. We hereby present the first targeted MS method with extremely high sensitivity for measuring endogenous phosphoproteins in human saliva EVs.

Clinical and Analytical Performance of ELISA Salivary Serologic Assay to Detect SARS-CoV-2 IgG in Children and Adults

Saliva is a promising matrix with several purposes. Our aim is to verify if salivary anti-SARS-CoV-2 antibody determination is suitable for monitoring immune responses. One hundred eighty-seven subjects were enrolled at University-Hospital Padova: 105 females (56.1%) and 82 males (43.9%), 95 (50.8%) children and 92 (49.2%) adults. Subjects self-collected saliva using Salivette; nineteen subjects collected three different samples within the day. A serum sample was obtained for all individuals. The N/S anti-SARS-CoV-2 salivary IgG (sal-IgG) and serum anti-SARS-CoV-2 S-RBD IgG (ser-IgG) were used for determining anti-SARS-CoV-2 antibodies. The mean (min-max) age was 9.0 (1-18) for children and 42.5 (20-61) for adults. Of 187 samples, 63 were negative for sal-IgG (33.7%), while 7 were negative for ser-IgG (3.7%). Spearman's correlation was 0.56 (p < 0.001). Sal-IgG and ser-IgG levels were correlated with age but not with gender, comorbidities, prolonged therapy, previous SARS-CoV-2 infection, or time from last COVID-19 infection/vaccination. The repeatability ranged from 23.8% (7.4 kAU/L) to 4.0% (3.77 kAU/L). The linearity of the assay was missed in 4/6 samples. No significant intrasubject differences were observed in sal-IgG across samples collected at different time points. Sal-IgG has good agreement with ser-IgG. Noninvasive saliva collection represents an alternative method for antibody measurement, especially in children.

[Modern approaches to studying the molecular mechanisms of lung functioning in normal and pathological conditions]

Problems with breathing and lung function are caused by the development of various lung diseases associated with lifestyle, harmful environmental factors and genetic predisposition. Knowledge of the molecular mechanisms of the development of the pathological process will allow on time identification of the disease or the development of targeted therapy. The article provides an overview of modern methods that make it possible to most accurately reproduce the structural, functional and mechanical properties of the lung (organ-on-a-chip), to perform non-invasive molecular studies of biomarkers of bronchopulmonary pathology using saliva diagnostics, as well as using DNA and RNA aptamers, verify tumor markers in biological samples of human tissue. Analysis of alterations in the pattern of protein glycosylation using glycodiagnostic methods makes it possible to detect lung cancer in the early stages.

Enhancing saliva diagnostics: The impact of amylase depletion on MALDI-ToF MS profiles as applied to COVID-19

Introduction

Human saliva contains a wealth of proteins that can be monitored for disease diagnosis and progression. Saliva, which is easy to collect, has been extensively studied for the diagnosis of numerous systemic and infectious diseases. However, the presence of amylase, the most abundant protein in saliva, can obscure the detection of low-abundance proteins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF MS), thus reducing its diagnostic utility.

Objectives

In this study, we used a device to deplete salivary amylase from water-gargle samples by affinity adsorption. Following depletion, saliva proteome profiling was performed using MALDI-ToF MS on gargle samples from individuals confirmed to have COVID-19 based on nasopharyngeal (NP) swab reverse transcription quantitative polymerase chain reaction (RT-qPCR).

Results

The depletion of amylase led to increased signal intensities of various peaks and the detection of previously unobserved peaks in the MALDI-ToF MS spectra. The overall specificity and sensitivity after amylase depletion were 100% and 85.17%, respectively, for detecting COVID-19.

Conclusion

This simple, rapid, and inexpensive technique for depleting salivary amylase can reveal spectral diversity in saliva using MALDI-ToF MS, expose low-abundance proteins, and assist in establishing novel biomarkers for diseases.

Functionalized optical fiber ball-shaped biosensor for label-free, low-limit detection of IL-8 protein

Detection of biomarkers for tracking disease progression is becoming increasingly important in biomedicine. Using saliva as a diagnostic sample appears to be a safe, cost-effective, and non-invasive approach. Salivary interleukin-8 levels demonstrate specific changes associated with diseases such as obstructive pulmonary disease, squamous cell carcinoma, oral cancer, and breast cancer. Traditional protein detection methods, such as enzyme-linked immunosorbent assay (ELISA), mass spectrometry, and Western blot are often expensive, complex, and time-consuming. In this study, an optical fiber-based biosensor was developed to detect salivary IL-8 protein in a label-free manner. The biosensor was able to achieve an ultra-low limit detection of 0.91 fM. Moreover, the tested concentration range was wide: from 273 aM to 59 fM. As a proof-of-concept for detecting the protein in real clinical samples, the detection was carried out in artificial saliva. It was possible to achieve high sensitivity for the target protein and minimal signal alterations for the control proteins.

Salivary proteomic profile of response to different resistance training protocols: A case report

Resistance training (RT) with blood flow restriction (BFR) or high intensity (HI) are effective to increase muscle mass. To understand this effect, techniques known as "omics" are used to identify possible biomarkers. This study analyzed the salivary proteomic profile of healthy individuals trained before and after two RT protocols both designed with eight exercises for upper- and lower-limbs, one performed at low percentage of one-maximum repetition (%1RM) with BFR technique, and other at high %1RM (HI) without BRF technique. Four healthy males between 18 and 28 years participated in the study. Stimulated saliva was collected before (BBFR/BHI) and immediately after (ABFR/AHI) the two RT protocols. All protein-related processing was performed using label-free proteomic. The difference in expression between groups was expressed as p < .05 for downregulated proteins and 1-p > .95 for upregulated proteins. There was difference in salivary flow between ABFR and BBFR (p = .005). For HI, 87 proteins were found after the practice and 119 before. Three hemoglobin isoforms were increased in AHI compared with BHI. In the BFR comparison, 105 proteins were identified after (ABFR) and 70 before (BBFR). Among those increased ABFR, we highlight five hemoglobin isoforms and Deleted in malignant brain tumors 1 protein. Between ABFR and AHI, 17 isoforms of histones, Transaldolase, Transketolase, Glyceraldehyde-3-phosphate dehydrogenase, and Antileukoproteinase were decreased ABFR. For HI, there was an increase in proteins related to oxidative stress and metabolism of the musculoskeletal system, compared with BFR. HI seems to induce higher anabolic signaling to muscle mass increase and antiatherosclerotic effects.

Expression of salivary levels of S100A7 in oral submucous fibrosis and oral leukoplakia

Aim

The aim of the study is to evaluate the expression of S100A7 levels in saliva of oral sub-mucous fibrosis, oral leukoplakia patients, and healthy control.

Materials and Methods

The study comprised of saliva samples from 15 patients each with clinically diagnosed oral sub-mucous fibrosis, oral leukoplakia, and healthy control. Salivary S100A7 levels were estimated using Enzyme-Linked Immunosorbent Assay. Statistical analysis was performed using SPSS. The significance level is fixed at 5% (α = 0.05). To compare the mean values of concentration between the disease group oral leukoplakia (OL) and oral submucous fibrosis (OSMF) and control, one-way analysis of variance was used followed by a post hoc test for multiple pairwise comparisons.

Results

The results of the study indicated a statistically significant increase in the salivary S100A7 level among the OSMF and OL when compared with the control group. When a pairwise comparison was done between OSMF with a control group and leukoplakia with a control group, a statistically significant difference was observed, subsequently while comparing OSMF with leukoplakia, and no statistically significant difference was observed.

Conclusion

Results from this study demonstrated increased S100A7 levels in OSMF and OL when compared with control group. This indicated that salivary S100A7 can be used as an adjunctive marker to identify patients at risk of progression into oral squamous cell carcinoma (OSCC).

Association of Ischemia-Modified Albumin (IMA) in Saliva, Serum, and Urine with Diagnosis of Chronic Kidney Disease (CKD) in Children: A Case-Control Study

BACKGROUND Ischemia-modified albumin (IMA) is a secreted biomarker for ischemic oxidative stress. This case-control study aimed to evaluate the association of ischemia-modified albumin (IMA) in saliva, serum, and urine with diagnosis of chronic kidney disease (CKD) in 24 children. MATERIAL AND METHODS The study involved 24 children with CKD. CKD was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) diagnostic criteria. The control group consisted of 24 healthy children who were matched for age and gender to the experimental group. The concentration of IMA was determined by the colorimetric method in non-stimulated whole saliva (NWS), stimulated whole saliva (SWS), serum, and urine of children with CKD. The Mann-Whitney U test was used for inter-group comparisons. RESULTS IMA levels were significantly higher in NWS (P=0.0082) and SWS (P=0.0014) of children with CKD than in the control group. The concentration of IMA in NWS was correlated with standard indicators of kidney function, including the estimated glomerular filtration rate (r=-0.798, P≤0.0001), stage of CKD (r=0.814, P≤0.0001), and serum creatinine (r=0.711, P≤0.0001) and urea levels (r=0.738, P≤0.0001). CONCLUSIONS Salivary IMA concentration depends on renal function in children. Salivary IMA discriminates children with end-stage kidney disease from children with mild and moderate CKD and healthy children with high sensitivity and specificity. Further research is required, including assessment of the diagnostic usefulness and validation of the biomarker in a clinical diagnostic study.

Identification of habit specific bacteria in human saliva through Next-Generation Sequencing

Characterization of human saliva through Next-Generation Sequencing has emerged as a valuable tool for understanding the complex microbial communities residing in the oral cavity. This study aims to investigate the habit-based variations in the salivary microbiome using Next-Generation Sequencing technology. Saliva samples were collected from a diverse population representing different habits, including smoking, alcohol consumption, and vegan diet. The DNA from the samples was extracted, and the V3-V4 region of the 16 S rRNA gene was amplified for Next-Generation Sequencing analysis. The obtained sequences were processed and analysed using bioinformatics tools to determine the microbial composition and diversity. Preliminary results revealed distinct microbial profiles associated with different habits, indicating the potential influence of different habits on the salivary microbiome. Smokers exhibited a higher abundance of certain pathogenic bacteria, while alcohol consumers showed alterations in microbial diversity compared to non-consumers. Furthermore, individuals with vegan diet demonstrated an increased prevalence of specific bacteria. These findings highlight the significance of habit-based characterization of the salivary microbiome and its potential implications in the presence of certain bacteria. Understanding the relationship between habits and the salivary microbiome could contribute to developing personalized approaches for estimating and identifying any particular individual. Further research is warranted to explore additional factors and expand the scope of habit-based analysis in saliva-based microbial characterization through Next-Generation Sequencing.

Beneficial or detrimental: Recruiting more types of benign cases for cancer diagnosis based on salivary glycopatterns

With the advantages of convenient, painless and non-invasive collection, saliva holds great promise as a valuable biomarker source for cancer detection, pathological assessment and therapeutic monitoring. Salivary glycopatterns have shown significant potential for cancer screening in recent years. However, the understanding of benign lesions at non-cancerous sites in cancer diagnosis has been overlooked. Clarifying the influence of benign lesions on salivary glycopatterns and cancer screening is crucial for advancing the development of salivary glycopattern-based diagnostics. In this study, 2885 samples were analyzed using lectin microarrays to identify variations in salivary glycopatterns according to the number, location, and type of lesions. By utilizing our previously published data of tumor-associated salivary glycopatterns, the performance of machine learning algorithm for cancer screening was investigated to evaluate the effect of adding benign disease cases to the control group. The results demonstrated that both the location and number of lesions had discernible effects on salivary glycopatterns. And it was also revealed that incorporating a broad range of benign diseases into the controls improved the classifier's performance in distinguishing cancer cases from controls. This finding holds guiding significance for enhancing salivary glycopattern-based cancer screening and facilitates their practical implementation in clinical settings.

Advances of hafnium based nanomaterials for cancer theranostics

Hafnium-based nanomaterials (Hf-NMs) have attracted the interest of numerous biomedical researchers by their unique properties. Recent years have witnessed significant advancements in the field of Hafnium-based nanomaterials, particularly in the context of cancer diagnosis and treatment. However, research in this area, especially concerning the clinical application of Hafnium-based nanomaterials, has not been thoroughly reviewed. This review will cover: 1) Classification and synthesis of Hafnium-based nanomaterials including Hafnium oxide nanomaterials, Hafnium Metal-Organic Frameworks/nanoscale coordination polymers (MOFs/NCPs); 2) Hafnium-based nanomaterials act as contrast enhancement agent for cancer imaging, and hafnium-based nanomaterials used for diagnosis in cancer liquid biopsy; 3) hafnium-based nanomaterials for cancer therapy, including hafnium-based nanomaterials for radiotherapy, hafnium-based nanomaterials for photodynamic therapy, hafnium-based nanomaterials for various combined therapy; and 4) Translation, toxicity, and safety for Hf-NMs in human and preclinical animal models. More attention will be given to the clinical translation of Hf-NMs in cancer.

Comparative analyses of salivary exosomal miRNAs for patients with or without lung cancer

Introduction: Lung cancer is the most frequent cause of cancer-related deaths worldwide. Exosomes are involved in different types of cancer, including lung cancer. Methods: We collected saliva from patients with (LC) or without (NC) lung cancer and successfully isolated salivary exosomes by ultracentrifugation. MiRNA sequencing was implemented for the exosome samples from NC and LC groups, dgeR was used to determine differentially expressed miRNAs (DE miRNAs), and quantitative real-time polymerase chain reaction (qPCR) was used to verify three differentially expressed microRNAs (miRNAs). Results: A total of 372 miRNAs were identified based on the sequencing results. Subsequently, 15 DE miRNAs were identified in LC vs. NC, including eight upregulated miRNAs and seven downregulated miRNAs. Some DE miRNAs were validated via qPCR. A total of 488 putative target genes of the upregulated DE miRNAs were found, and the functional analyses indicated that numerous target genes were enriched in the pathways associated with cancer. Discussion: This suggests that miRNAs of salivary exosomes might have the potential to be used as biomarkers for prediction and diagnosis of lung cancer.

Effects of Denture Treatment on Salivary Metabolites: A Pilot Study

Symptoms of oral discomfort such as dry mouth are common in older people wearing dentures. Such symptoms are mainly treated symptomatically. Many of these symptoms are related to saliva, and associations with salivary volume have been reported. Although denture treatment improves symptoms by increasing the amount of saliva, the effects on salivary components remain unclear. This study aimed to investigate the effects of denture treatment on salivary metabolite changes based on salivary metabolome analyses. We enrolled 21 patients requiring denture treatment. At the first visit, and after completion of denture treatment, saliva outflow was measured under resting and stimulated conditions, samples for salivary metabolite analysis were collected, and masticatory efficiency was tested. In all participants, masticatory efficiency increased after denture treatment. Moreover, the amounts of resting and stimulated saliva were increased. Using salivary metabolome analysis, 61 salivary metabolites were detected. Substantial concentration changes were observed for 4 and 21 metabolites in resting and stimulated saliva, respectively. The four metabolites common to both saliva tests had significantly lower concentrations after treatment. These results suggest that the improvement in masticatory function by dentures is related not only to salivary secretion volume, but also to salivary metabolite composition.

Salivaomics to decode non-coding RNAs in oral cancer. A narrative review

Oral cancer is the most debilitating disease which affects the orderly life of a human. With so much advancement in research and technology, the average life expectancy of an individual with oral cancer appears to be about 5 years. The changing trend in incidence of oral cancer among young individuals and women without tobacco habits are ascending. Non habit related oral cancer are taking centre stage and multiple factors which induce complex biology are associated in such scenarios. To decipher the aetiology and to understand the process, these cancerous conditions are to be studied at molecular level. Saliva, the most non-invasively obtained body fluid are assessed for biomarkers exclusively in liquid biopsy. This fluid gives a huge platform to study number of molecules associated with oral cancer. Non coding RNAs are transcripts with no protein coding function. They are gaining more importance in recent times. Long noncoding RNA, microRNA are major types of noncoding transcriptome that influences in progression of oral cancer. They seem to play an important role in health and disease. Apart from these, circulating tumour cells, exosomes, extracellular vesicles, antigens and other proteins can be studied from saliva. This review is aimed to update the knowledge on current biomarkers in saliva associated with oral cancer and their epigenetic role in disease progression as well recent advances in detecting these markers to identify the stage of the disease, which will help in deciding the treatment protocol.