Cross-kingdom RNA interference mediated by insect salivary microRNAs may suppress plant immunity.

Communication between insects and plants relies on the exchange of bioactive molecules that traverse the species interface. Although proteinic effectors have been extensively studied, our knowledge of other molecules involved in this process remains limited. In this study, we investigate the role of salivary microRNAs (miRNAs) from the rice planthopper Nilaparvata lugens in suppressing plant immunity. A total of three miRNAs were confirmed to be secreted into host plants during insect feeding. Notably, the sequence-conserved miR-7-5P is specifically expressed in the salivary glands of N. lugens and is secreted into saliva, distinguishing it significantly from homologues found in other insects. Silencing miR-7-5P negatively affects N. lugens feeding on rice plants, but not on artificial diets. The impaired feeding performance of miR-7-5P-silenced insects can be rescued by transgenic plants overexpressing miR-7-5P. Through target prediction and experimental testing, we demonstrate that miR-7-5P targets multiple plant genes, including the immune-associated bZIP transcription factor 43 (OsbZIP43). Infestation of rice plants by miR-7-5P-silenced insects leads to the increased expression of OsbZIP43, while the presence of miR-7-5P counteracts this upregulation effect. Furthermore, overexpressing OsbZIP43 confers plant resistance against insects which can be subverted by miR-7-5P. Our findings suggest a mechanism by which herbivorous insects have evolved salivary miRNAs to suppress plant immunity, expanding our understanding of cross-kingdom RNA interference between interacting organisms.

Malaria: influence of Anopheles mosquito saliva on Plasmodium infection.

Malaria is caused by Plasmodium protozoa that are transmitted by anopheline mosquitoes. Plasmodium sporozoites are released with saliva when an infected female mosquito takes a blood meal on a vertebrate host. Sporozoites deposited into the skin must enter a blood vessel to start their journey towards the liver. After migration out of the mosquito, sporozoites are associated with, or in proximity to, many components of vector saliva in the skin. Recent work has elucidated how Anopheles saliva, and components of saliva, can influence host-pathogen interactions during the early stage of Plasmodium infection in the skin. Here, we discuss how components of Anopheles saliva can modulate local host responses and affect Plasmodium infectivity. We hypothesize that therapeutic strategies targeting mosquito salivary proteins can play a role in controlling malaria and other vector-borne diseases.

Guardians of the oral and nasopharyngeal galaxy: IgA and protection against SARS-CoV-2 infection.

In early 2020, a global emergency was upon us in the form of the coronavirus disease 2019 (COVID-19) pandemic. While horrific in its health, social and economic devastation, one silver lining to this crisis has been a rapid mobilization of cross-institute, and even cross-country teams that shared common goals of learning as much as we could as quickly as possible about the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and how the immune system would respond to both the virus and COVID-19 vaccines. Many of these teams were formed by women who quickly realized that the classical model of "publish first at all costs" was maladaptive for the circumstances and needed to be supplanted by a more collaborative solution-focused approach. This review is an example of a collaboration that unfolded in separate countries, first Canada and the United States, and then also Israel. Not only did the collaboration allow us to cross-validate our results using different hands/techniques/samples, but it also took advantage of different vaccine types and schedules that were rolled out in our respective home countries. The result of this collaboration was a new understanding of how mucosal immunity to SARS-CoV-2 infection vs COVID-19 vaccination can be measured using saliva as a biofluid, what types of vaccines are best able to induce (limited) mucosal immunity, and what are potential correlates of protection against breakthrough infection. In this review, we will share what we have learned about the mucosal immune response to SARS-CoV-2 and to COVID-19 vaccines and provide a perspective on what may be required for next-generation pan-sarbecoronavirus vaccine approaches.

Stability of influenza A virus in droplets and aerosols is heightened by the presence of commensal respiratory bacteria.

Aerosol transmission remains a major challenge for control of respiratory viruses, particularly those causing recurrent epidemics, like influenza A virus (IAV). These viruses are rarely expelled alone, but instead are embedded in a consortium of microorganisms that populate the respiratory tract. The impact of microbial communities and inter-pathogen interactions upon stability of transmitted viruses is well-characterized for enteric pathogens, but is under-studied in the respiratory niche. Here, we assessed whether the presence of five different species of commensal respiratory bacteria could influence the persistence of IAV within phosphate-buffered saline and artificial saliva droplets deposited on surfaces at typical indoor air humidity, and within airborne aerosol particles. In droplets, presence of individual species or a mixed bacterial community resulted in 10- to 100-fold more infectious IAV remaining after 1 h, due to bacterial-mediated flattening of drying droplets and early efflorescence. Even when no efflorescence occurred at high humidity or the bacteria-induced changes in droplet morphology were abolished by aerosolization instead of deposition on a well plate, the bacteria remained protective. Staphylococcus aureus and Streptococcus pneumoniae were the most stabilizing compared to other commensals at equivalent density, indicating the composition of an individual's respiratory microbiota is a previously unconsidered factor influencing expelled virus persistence.IMPORTANCEIt is known that respiratory infections such as coronavirus disease 2019 and influenza are transmitted by release of virus-containing aerosols and larger droplets by an infected host. The survival time of viruses expelled into the environment can vary depending on temperature, room air humidity, UV exposure, air composition, and suspending fluid. However, few studies consider the fact that respiratory viruses are not alone in the respiratory tract-we are constantly colonized by a plethora of bacteria in our noses, mouth, and lower respiratory system. In the gut, enteric viruses are known to be stabilized against inactivation and environmental decay by gut bacteria. Despite the presence of a similarly complex bacterial microbiota in the respiratory tract, few studies have investigated whether viral stabilization could occur in this niche. Here, we address this question by investigating influenza A virus stabilization by a range of commensal bacteria in systems representing respiratory aerosols and droplets.

Assessing suspension and infectivity times of virus-loaded aerosols involved in airborne transmission.

Airborne transmission occurs through droplet-mediated transport of viruses following the expulsion of an aerosol by an infected host. Transmission efficiency results from the interplay between virus survival in the drying droplet and droplet suspension time in the air, controlled by the coupling between water evaporation and droplet sedimentation. Furthermore, droplets are made of a respiratory fluid and thus, display a complex composition consisting of water and nonvolatile solutes. Here, we quantify the impact of this complex composition on the different phenomena underlying transmission. Solutes lead to a nonideal thermodynamic behavior, which sets an equilibrium droplet size that is independent of relative humidity. In contrast, solutes do not significantly hinder transport due to their low initial concentration. Realistic suspension times are computed and increase with increasing relative humidity or decreasing temperature. By uncoupling drying and suspended stages, we observe that enveloped viruses may remain infectious for hours in dried droplets. However, their infectivity decreases with increasing relative humidity or temperature after dozens of minutes. Examining expelled droplet size distributions in the light of these results leads to distinguishing two aerosols. Most droplets measure between 0 and 40 µm and compose an aerosol that remains suspended for hours. Its transmission efficiency is controlled by infectivity, which decreases with increasing humidity and temperature. Larger droplets form an aerosol that only remains suspended for minutes but corresponds to a much larger volume and thus, viral load. Its transmission efficiency is controlled by droplet suspension time, which decreases with increasing humidity and decreasing temperature.

Interference with LTßR signaling by tick saliva facilitates transmission of Lyme disease spirochetes.

Lyme spirochetes have coevolved with ticks to optimize transmission to hosts using tick salivary molecules (TSMs) to counteract host defenses. TSMs modulate various molecular events at the tick-host interface. Lymphotoxin-beta receptor (LTßR) is a vital immune receptor and plays protective roles in host immunity against microbial infections. We found that Ltbr knockout mice were more susceptible to Lyme disease spirochetes, suggesting the involvement of LTßR signaling in tick-borne Borrelia infection. Further investigation showed that a 15-kDa TSM protein from Ixodes persulcatus (I. persulcatus salivary protein; IpSAP) functioned as an immunosuppressant to facilitate the transmission and infection of Lyme disease spirochetes. IpSAP directly interacts with LTßR to block its activation, thus inhibiting the downstream signaling and consequently suppressing immunity. IpSAP immunization provided mice with significant protection against I. persulcatus-mediated Borrelia garinii infection. Notably, the immunization showed considerable cross-protection against other Borrelia infections mediated by other ixodid ticks. One of the IpSAP homologs from other ixodid ticks showed similar effects on Lyme spirochete transmission. Together, our findings suggest that LTßR signaling plays an important role in blocking the transmission and pathogenesis of tick-borne Lyme disease spirochetes, and that IpSAP and its homologs are promising candidates for broad-spectrum vaccine development.

Integrative analysis of transcriptome and proteome in primary Sjögren syndrome.

OBJECTIVE: Primary Sjögren's syndrome (pSS) is a intricate autoimmune disease mainly characterized of immune-mediated destruction of exocrine tissues, such as salivary and lacrimal glands, occurring dry mouth and eyes. Although some breakthroughs in understanding pSS have been uncovered, many questions remain about its pathogenesis, especially the internal relations between exocrine glands and secretions. METHOD: Transcriptomic and proteomic analyses were conducted on salivary tissues and saliva in experimental Sjögren syndrome (ESS). The ESS model was established by immunization with salivary gland protein. The expression of mRNAs and proteins in salivary tissues and saliva were determined by high-throughput sequencing transcriptomic analysis and LC-MS/MS-based proteome, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were used to recognize dysregulated genes and proteins. The association between RNA and protein abundance was investigated to provides a comprehensive understanding of RNA-protein correlations in the pathogenesis of pSS. RESULTS: As a result, we successfully established the ESS model. We recognized 3221 differentially expressed genes (DEGs) and 253 differentially expressed proteins (DEPs). The sample analysis showed that 61 proteins overlapped through the integrative analysis of transcriptomics and proteomics data. The enrichment pathway analysis of DEGs and DEPs in samples showed alterations in renin-angiotensin-system (RAS), lysosome, and apoptosis. Notably, we found that some genes, such as AGT, FN1, Klk1b26, Klk1, Klk1b5, Klk1b3 had a consistent trend in the regulation at the RNA and protein levels and might be potential diagnostic biomarkers of pSS. CONCLUSION: Herein, we found critical processes and potential biomakers that may contribute to pSS pathogenesis by analyzing dysregulated genes and pathways. Additionally, the integrative multi-omics datasets provided additional insight into understanding complicated disease mechanisms.

Saliva antibody profiles are associated with reaction threshold and severity of peanut allergic reactions.

BACKGROUND: Reaction threshold and severity in food allergy are difficult to predict, and noninvasive predictors are lacking. OBJECTIVE: We sought to determine the relationships between pre-challenge levels of peanut (PN)-specific antibodies in saliva and reaction threshold, severity, and organ-specific symptoms during PN allergic reactions. METHODS: We measured PN-specific antibody levels in saliva collected from 127 children with suspected PN allergy before double-blind, placebo-controlled PN challenges in which reaction threshold, severity, and symptoms were rigorously characterized. Low threshold (LT) PN allergy was defined as reaction to <300 mg of PN protein cumulatively consumed. A consensus severity grading system was used to grade severity. We analyzed associations between antibody levels and reaction threshold, severity, and organ-specific symptoms. RESULTS: Among the 127 children, those with high pre-challenge saliva PN IgE had higher odds of LT PN allergy (odds ratio [OR] 3.9, 95% CI 1.6-9.5), while those with high saliva PN IgA:PN IgE ratio or PN IgG4:PN IgE ratio had lower odds of LT PN allergy (OR 0.3, 95% CI 0.1-0.8; OR 0.4, 95% CI 0.2-0.9). Children with high pre-challenge saliva PN IgG4 had lower odds of severe PN reactions (OR 0.4, 95% CI 0.2-0.9). Children with high saliva PN IgE had higher odds of respiratory symptoms (OR 8.0, 95% CI 2.2-26.8). Saliva PN IgE modestly correlated with serum PN IgE levels (Pearson r = 0.31, P = .0004). High and low saliva PN IgE levels further distinguished reaction threshold and severity in participants stratified by serum PN IgE, suggesting endotypes. CONCLUSIONS: Saliva PN antibodies could aid in noninvasive risk stratification of PN allergy threshold, severity, and organ-specific symptoms.

Mapping Conformational Changes in the Saliva Proteome Potentially Associated with Oral Cancer Aggressiveness.

Diverse proteomics-based strategies have been applied to saliva to quantitatively identify diagnostic and prognostic targets for oral cancer. Considering that these targets may be regulated by events that do not imply variation in protein abundance levels, we hypothesized that changes in protein conformation can be associated with diagnosis and prognosis, revealing biological processes and novel targets of clinical relevance. For this, we employed limited proteolysis-mass spectrometry in saliva samples to explore structural alterations, comparing the proteome of healthy control and oral squamous cell carcinoma (OSCC) patients with and without lymph node metastasis. Thirty-six proteins with potential structural rearrangements were associated with clinical patient features including transketolase and its interacting partners. Moreover, N-glycosylated peptides contribute to structural rearrangements of potential diagnostic and prognostic markers. Altogether, this approach utilizes saliva proteins to search for targets for diagnosing and prognosing oral cancer and can guide the discovery of potential regulated sites beyond protein-level abundance.

Beyond Bites: Differential Role of Fall Armyworm Oral Secretions and Saliva in Modulating Sorghum Defenses.

Flavonoids are major plant secondary metabolites that provide defense against several insect pests. Previously, it has been shown that sorghum (Sorghum bicolor) flavonoids are required for providing resistance to fall armyworm (FAW; Spodoptera frugiperda), which is an important chewing insect pest on several crops. We demonstrate here the role of FAW oral cues in modulating sorghum flavonoid defenses. While feeding, chewing insects release two kinds of oral cues: oral secretions (OS)/regurgitant and saliva. Our results indicate that FAW OS induced the expression of genes related to flavonoid biosynthesis and total flavonoids, thereby enhancing sorghum's defense against FAW larvae. Conversely, FAW saliva suppressed the flavonoid-based defenses and promoted FAW caterpillar growth, independent of the FAW salivary component, glucose oxidase (GOX). Thus, we infer that different oral cues in FAW may have contrasting roles in altering sorghum defenses. These findings expand our understanding of the precise modes of action of caterpillar oral cues in modulating plant defenses and help in designing novel pest management strategies against FAW in this vital cereal crop. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Comparative transcriptomic analysis of salivary glands between the zoophytophagous Cyrtorhinus lividipennis and the phytozoophagous Apolygus lucorum.

BACKGROUND: Saliva plays a crucial role in shaping the feeding behavior of insects, involving processes such as food digestion and the regulation of interactions between insects and their hosts. Cyrtorhinus lividipennis serves as a predominant natural enemy of rice pests, while Apolygus lucorum, exhibiting phytozoophagous feeding behavior, is a destructive agricultural pest. In this study, a comparative transcriptome analysis, incorporating the published genomes of C.lividipennis and A.lucorum, was conducted to reveal the role of salivary secretion in host adaptation. RESULTS: In contrast to A.lucorum, C.lividipennis is a zoophytophagous insect. A de novo genome analysis of C.lividipennis yielded 19,706 unigenes, including 16,217 annotated ones. On the other hand, A.lucorum had altogether 20,111 annotated genes, as obtained from the published official gene set (20,353 unigenes). Functional analysis of the top 1,000 salivary gland (SG)-abundant genes in both insects revealed that the SG was a dynamically active tissue engaged in protein synthesis and secretion. Predictions of other tissues and signal peptides were compared. As a result, 94 and 157 salivary proteins were identified in C.lividipennis and A.lucorum, respectively, and were categorized into 68 and 81 orthogroups. Among them, 26 orthogroups were shared, potentially playing common roles in digestion and detoxification, including several venom serine proteases. Furthermore, 42 and 55 orthogroups were exclusive in C.lividipennis and A.lucorum, respectively, which were exemplified by a hyaluronidase in C.lividipennis that was associated with predation, while polygalacturonases in A.lucorum were involved in mesophyll-feeding patterns. CONCLUSIONS: Findings in this study provide a comprehensive insight into saliva secretions in C.lividipennis and A.lucorum via a transcriptome approach, reflecting the intricate connections between saliva secretions and feeding behaviors. It is found that conserved salivary secretions are involved in shaping the overlapping feeding patterns, while a plethora of unique salivary secretions may drive the evolution of specific feeding behaviors crucial for their survival. These results enhance our understanding of the feeding mechanisms in different insects from the perspective of saliva and contribute to future environmentally friendly pest control by utilizing predatory insects.

Effect of salivary gland removal on taste preference in mice.

To evaluate the effect of decreased salivary secretion on taste preference, we investigated taste preference for five basic tastes by a 48 h two-bottle preference test using a mouse model (desalivated mice) that underwent surgical removal of three major salivary glands: the parotid, submandibular, and sublingual glands. In the desalivated mice, the avoidance behaviors for bitter and salty tastes and the attractive behaviors for sweet and umami tastes were significantly decreased. We confirmed that saliva is necessary to maintain normal taste preference. To estimate the cause of the preference changes, we investigated the effects of salivary gland removal on the expression of taste-related molecules in the taste buds. No apparent changes were observed in the expression levels or patterns of taste-related molecules after salivary gland removal. When the protein concentration and composition in the saliva were compared between the control and desalivated mice, the protein concentration decreased and its composition changed after major salivary gland removal. These results suggest that changes in protein concentration and composition in the saliva may be one of the factors responsible for the changes in taste preferences observed in the desalivated mice.

Validated WGS and WES protocols proved saliva-derived gDNA as an equivalent to blood-derived gDNA for clinical and population genomic analyses.

BACKGROUND: Whole exome sequencing (WES) and whole genome sequencing (WGS) have become standard methods in human clinical diagnostics as well as in population genomics (POPGEN). Blood-derived genomic DNA (gDNA) is routinely used in the clinical environment. Conversely, many POPGEN studies and commercial tests benefit from easy saliva sampling. Here, we evaluated the quality of variant call sets and the level of genotype concordance of single nucleotide variants (SNVs) and small insertions and deletions (indels) for WES and WGS using paired blood- and saliva-derived gDNA isolates employing genomic reference-based validated protocols. METHODS: The genomic reference standard Coriell NA12878 was repeatedly analyzed using optimized WES and WGS protocols, and data calls were compared with the truth dataset published by the Genome in a Bottle Consortium. gDNA was extracted from the paired blood and saliva samples of 10 participants and processed using the same protocols. A comparison of paired blood-saliva call sets was performed in the context of WGS and WES genomic reference-based technical validation results. RESULTS: The quality pattern of called variants obtained from genomic-reference-based technical replicates correlates with data calls of paired blood-saliva-derived samples in all levels of tested examinations despite a higher rate of non-human contamination found in the saliva samples. The F1 score of 10 blood-to-saliva-derived comparisons ranged between 0.8030-0.9998 for SNVs and between 0.8883-0.9991 for small-indels in the case of the WGS protocol, and between 0.8643-0.999 for SNVs and between 0.7781-1.000 for small-indels in the case of the WES protocol. CONCLUSION: Saliva may be considered an equivalent material to blood for genetic analysis for both WGS and WES under strict protocol conditions. The accuracy of sequencing metrics and variant-detection accuracy is not affected by choosing saliva as the gDNA source instead of blood but much more significantly by the genomic context, variant types, and the sequencing technology used.

Association of opium use and tobacco smoking with α-, ß-, and γ-human papillomavirus oral infection.

Head and neck squamous cell carcinomas (HNSCCs) are linked to tobacco smoking, opium use, and human papillomavirus (HPV) infection. However, little is known about the association of HPV infection with risk factors of HNSCCs, including opium and tobacco use. This cross-sectional analysis of a national multi-center case-control study in Iran included 498 HNSCC cases and 242 controls. We investigated the association of opium and tobacco use with α- (n = 21), ß- (n = 46), and γ-HPV (n = 52) types in saliva samples using type-specific bead-based multiplex genotyping assays (TS-MPG). We found that α-HPV positivity was significantly associated with tobacco smoking (OR = 10.35; 95% CI = 1.15, 93; p = .03), but not with opium use (OR = 1.06; 95% CI = 0.41, 2.76; p = .89). Additionally, tobacco smoking correlated with an elevated risk of ß-species 2 HPV infection (OR = 1.28; 95% CI = 1.04, 1.58; p = .020). Conversely, opium use showed a positive association with γ-species 12 HPV infection (OR = 5.67; 95% CI = 1.43, 22.44; p = .013). These findings indicate that tobacco and opium use may influence the risk of HPV infection in different ways depending on the HPV genus and species. Further studies are needed to replicate these findings in other populations.

Nociception related biomolecules in the adult human saliva: A scoping review with additional quantitative focus on cortisol.

Nociception related salivary biomolecules can be useful patients who are not able to self-report pain. We present the existing evidence on this topic using the PRISMA-ScR guidelines and a more focused analysis of cortisol change after cold pain induction using the direction of effect analysis combined with risk of bias analysis using ROBINS-I. Five data bases were searched systematically for articles on adults with acute pain secondary to disease, injury, or experimentally induced pain. Forty three articles met the inclusion criteria for the general review and 11 of these were included in the cortisol-cold pain analysis. Salivary melatonin, kallikreins, pro-inflammatory cytokines, soluable TNF-α receptor II, secretory IgA, testosterone, salivary α-amylase (sAA) and, most commonly, cortisol have been studied in relation to acute pain. There is greatest information about cortisol and sAA which both rise after cold pain when compared with other modalities. Where participants have been subjected to both pain and stress, stress is consistently a more reliable predictor of salivary biomarker change than pain. There remain considerable challenges in identifying biomarkers that can be used in clinical practice to guide the measurement of nociception and treatment of pain. Standardization of methodology and researchers' greater awareness of the factors that affect salivary biomolecule concentrations are needed to improve our understanding of this field towards creating a clinically relevant body of evidence.

Horizontally Transferred Salivary Protein Promotes Insect Feeding by Suppressing Ferredoxin-Mediated Plant Defenses.

Herbivorous insects such as whiteflies, planthoppers, and aphids secrete abundant orphan proteins to facilitate feeding. Yet, how these genes are recruited and evolve to mediate plant-insect interaction remains unknown. In this study, we report a horizontal gene transfer (HGT) event from fungi to an ancestor of Aleyrodidae insects approximately 42 to 190 million years ago. BtFTSP1 is a salivary protein that is secreted into host plants during Bemisia tabaci feeding. It targets a defensive ferredoxin 1 in Nicotiana tabacum (NtFD1) and disrupts the NtFD1-NtFD1 interaction in plant cytosol, leading to the degradation of NtFD1 in a ubiquitin-dependent manner. Silencing BtFTSP1 has negative effects on B. tabaci feeding while overexpressing BtFTSP1 in N. tabacum benefits insects and rescues the adverse effect caused by NtFD1 overexpression. The association between BtFTSP1 and NtFD1 is newly evolved after HGT, with the homologous FTSP in its fungal donor failing to interact and destabilize NtFD1. Our study illustrates the important roles of horizontally transferred genes in plant-insect interactions and suggests the potential origin of orphan salivary genes.

Free Salivary Amino Acid Profile in Breast Cancer: Clinicopathological and Molecular Biological Features.

The study of salivary amino acid profiles has attracted the attention of researchers, since amino acids are actively involved in most metabolic processes, including breast cancer. In this study, we analyzed the amino acid profile of saliva in a sample including all molecular biological subtypes of breast cancer to obtain a more complete picture and evaluate the potential utility of individual amino acids or their combinations for diagnostic purposes. This study included 116 patients with breast cancer, 24 patients with benign breast disease, and 25 healthy controls. From all patients, strictly before the start of treatment, saliva samples were collected, and the quantitative content of 26 amino acids was determined. Statistically significant differences between the three groups are shown in the content of Asp, Gly, Leu + Ile, Orn, Phe, Pro, Thr, and Tyr. To differentiate the three groups from each other, a decision tree was built. To construct it, we selected those amino acids for which the change in concentrations in the subgroups was multidirectional (GABA, Hyl, Arg, His, Pro, and Car). For the first time, it is shown that the amino acid profile of saliva depends on the molecular biological subtype of breast cancer. The most significant differences are shown for the luminal B HER2-positive and TNBC subgroups. In our opinion, it is critically important to consider the molecular biological subtype of breast cancer when searching for potential diagnostic markers.

Salivary metabolomic biomarkers for non-invasive lung cancer detection.

Identifying novel biomarkers for early detection of lung cancer is crucial. Non-invasively available saliva is an ideal biofluid for biomarker exploration; however, the rationale underlying biomarker detection from organs distal to the oral cavity in saliva requires clarification. Therefore, we analyzed metabolomic profiles of cancer tissues compared with those of adjacent non-cancerous tissues, as well as plasma and saliva samples collected from patients with lung cancer (n = 109 pairs). Additionally, we analyzed plasma and saliva samples collected from control participants (n = 83 and 71, respectively). Capillary electrophoresis-mass spectrometry and liquid chromatography-mass spectrometry were performed to comprehensively quantify hydrophilic metabolites. Paired tissues were compared, revealing 53 significantly different metabolites. Plasma and saliva showed 44 and 40 significantly different metabolites, respectively, between patients and controls. Of these, 12 metabolites exhibited significant differences in all three comparisons and primarily belonged to the polyamine and amino acid pathways; N1-acetylspermidine exhibited the highest discrimination ability. A combination of 12 salivary metabolites was evaluated using a machine learning method to differentiate patients with lung cancer from controls. Salivary data were randomly split into training and validation datasets. Areas under the receiver operating characteristic curve were 0.744 for cross-validation using training data and 0.792 for validation data. This model exhibited a higher discrimination ability for N1-acetylspermidine than that for other metabolites. The probability of lung cancer calculated using this model was independent of most patient characteristics. These results suggest that consistently different salivary biomarkers in both plasma and lung tissues might facilitate non-invasive lung cancer screening.

Salivary metabolomic biomarkers for esophageal and gastric cancers by liquid chromatography-mass spectrometry.

Early detection of esophageal and gastric cancers is essential for patients' prognosis; however, optimal noninvasive screening tests are currently not available. Saliva is a biofluid that is readily available, allowing for frequent screening tests. Thus, we explored salivary diagnostic biomarkers for esophageal and gastric cancers using metabolomic analyses. Saliva samples were collected from patients with esophageal (n = 50) and gastric cancer (n = 63), and patients without cancer as controls (n = 20). Salivary metabolites were analyzed by liquid chromatography-mass spectrometry to identify salivary biomarkers. We also examined the metabolic profiles of gastric cancer tissues and compared them with the salivary biomarkers. The sensitivity of the diagnostic models based on salivary biomarkers was assessed by comparing it with that of serum tumor markers. Additionally, using postoperative saliva samples collected from patients with gastric cancer, we analyzed the changes in the biomarkers' concentrations before and after surgery. Cytosine was detected as a salivary biomarker for gastric cancer, and cytosine, 2-oxoglutarate, and arginine were detected as salivary biomarkers for esophageal cancer. Cytidine, a cytosine nucleotide, showed decreased concentrations in gastric cancer tissues. The sensitivity of the diagnostic models for esophageal and gastric cancers was 66.0% and 47.6%, respectively, while that of serum tumor markers was 40%. Salivary cytosine concentration increased significantly postoperatively relative to the preoperative value. In summary, we identified salivary biomarkers for esophageal and gastric cancers, which showed diagnostic sensitivity at least comparable to that of serum tumor markers. Salivary metabolomic tests could be promising screening tests for these types of cancer.

Is Salivary Α-Amylase a Reliable Indicator of Psychological Status and Quality of Life in Patients with Oral Lichen Planus: a Case-Control Study.

BACKGROUND/AIMS: The objectives of our study were to determine salivary α-amylase activity (stress biomarker) and its association with psychological status and quality of life (QoL), disease duration and intensity of symptoms (pain/burning) in patients with OLP. METHODS: A total of 50 subjects participated in this case-control study: 30 patients with oral lichen planus (OLP); 20 control subjects. Unstimulated whole saliva (UWS) was collected between 9 and 10 am to avoid diurnal fluctuations. Psychological status was assessed using the Croatian validated version of the original Depression, Anxiety and Stress Scale (DASS-21). The impact of oral health on QoL was assessed using the Croatian version of the Oral Health Impact Profile Questionnaire (OHIP-CRO14). RESULTS: There was no statistically significant difference in salivary α-amylase activity between patients with OLP (N=30) and control subjects (N=20) (133813.3 vs. 166815.5 U/L, p=0.314; t-test). Depression, anxiety and stress showed no statistically significant difference between patients with OLP and control subjects (p=0.076, p=0.111, p=0.209; t-test). The patients with OLP had statistically significantly poorer QoL (total) compared to control subjects (p=0.004, t-test). There was a moderate positive correlation between symptom intensity (pain/burning) and poor QoL (total) (r=0.584, p<0.001), the OHIP-CRO14 dimension "physical pain" (r=0.661, p<0.001), "psychological impossibility" (r=0.555, p<0.01), "handicap" (r=0.546, p<0.01). CONCLUSION: Although salivary α-amylase showed no statistically significant difference between patients with OLP and control subjects, the patients with OLP had poorer psychological status (three times higher scores for depression and two times higher scores for anxiety) and poorer QoL compared to the control subjects. Recognising and treating mental disorders in patients with OLP is important in order to break the "vicious circle" and achieve a better QoL in these patients.