Salivary Biomarkers in Psychoneuroimmunology

Timing matters: A meta-analysis on the dynamic effect of stress on salivary immunoglobulin

The impact of psychological stress on physiological systems has been a focus of extensive research, particularly in understanding its diverse effects on immune system activity and disease risk. This meta-analysis explores the dynamic effect of acute stress on salivary immunoglobulin-A (S-IgA) levels, a key biomarker for secretory immunity within the oral environment. Analyzing data from 34 samples comprising 87 effect sizes and a total of 1,025 subjects, a multi-level approach is employed to account for the temporal variability in measuring the stress response. The results reveal a significant increase in S-IgA levels peaking around 10 min after stress exposure, followed by a return to baseline levels approximately 30 min later. In addition, the meta-analysis identified several research gaps of the extant literature, such as limitations in the considered time lag after stress. In conclusion, the findings emphasize the temporal nuances of the S-IgA response to stress, which can help to infer potential biological pathways and guide sampling designs in future studies. Further, we highlight the use of a multi-level meta-analysis approach to investigate the temporal dependencies of the interplay between stress and immune functioning.

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.

Exploring the Relationship between Psychoneuroimmunology and Oral Diseases: A Comprehensive Review and Analysis

The relationship between psychoneuroimmunology (PNI) and oral health has recently garnered increasing attention due to the intricate interaction among psychological factors, the nervous system, immune responses, and oral diseases. This comprehensive review aims to elucidate the multifaceted connections between PNI and various oral conditions and conduct an in-depth analysis. Psychological factors, such as stress, anxiety, and depression, have been linked to oral microbiome alterations and immune function and the development and progression of oral diseases, such as periodontal disorders, oral ulcers, and temporomandibular disorders. Conversely, oral health conditions, particularly chronic periodontitis, have been associated with systemic inflammation, affecting mental health and overall well-being through neuroendocrine-immune pathways. Moreover, neural mechanisms, including the brain-gut axis and the autonomic nervous system, significantly influenced oral health through immune modulation and inflammatory responses. Understanding these complex interactions has implications for therapeutic interventions that target both psychological well-being and oral health outcomes. This review synthesizes current research findings from various disciplines, including immunology, neuroscience, dentistry, and psychology, to offer a comprehensive understanding of the bidirectional relationship between PNI and oral diseases. The implications of these interactions on treatment strategies, preventive measures, and interdisciplinary approaches underscore the need for integrated healthcare models that address psychological and oral health aspects to improve outcomes and quality of life in patients.

Extensive comparison of salivary collection, transportation, preparation, and storage methods: a systematic review

BACKGROUND

Human saliva as a bodily fluid-similar to blood-is utilized for diagnostic purposes. Unlike blood sampling, collecting saliva is non-invasive, inexpensive, and readily accessible. There are no previously published systematic reviews regarding different collection, transportation, preparation, and storage methods for human saliva.

DESIGN

This study has been prepared and organized according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020 guidelines. This systematic review has been registered at PROSPERO (Registration ID: CRD42023415384). The study question according to the PICO format was as followed: Comparison of the performance (C) of different saliva sampling, handling, transportation, and storage techniques and methods (I) assessed for analyzing stimulated or unstimulated human saliva (P and O). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

Twenty-three descriptive human clinical studies published between 1995 and 2022 were included. Eight categories of salivary features and biomarkers were investigated (i.e., salivary flow rate, total saliva quantity, total protein, cortisol, testosterone, DNA quality and quantity, pH and buffering pH). Twenty-two saliva sampling methods/devices were utilized. Passive drooling, Salivette®, and spitting were the most utilized methods. Sampling times with optimum capabilities for cortisol, iodine, and oral cancer metabolites are suggested to be 7:30 AM to 9:00 AM, 10:30 AM to 11:00 AM, and 14:00 PM to 20:00 PM, respectively. There were 6 storage methods. Centrifuging samples and storing them at -70 °C to -80 °C was the most utilized storage method. For DNA quantity and quality, analyzing samples immediately after collection without centrifuging or storage, outperformed centrifuging samples and storing them at -70 °C to -80 °C. Non-coated Salivette® was the most successful method/device for analyzing salivary flow rate.

CONCLUSION

It is highly suggested that scientists take aid from the reported categorized outcomes, and design their study questions based on the current voids for each method/device.

The utility of salivary CRP and IL-6 as a non-invasive measurement evaluated in patients with COVID-19 with and without diabetes

Background

The available evidence suggests that inflammatory responses, in both systemic and oral tissue, contribute to the pathology of COVID-19 disease. Hence, studies of inflammation biomarkers in oral fluids, such as saliva, might be useful to better specify COVID-19 features.

Methods

In the current study, we performed quantitative real-time PCR to measure salivary levels of C-reactive protein (CRP) and interleukin-6 (IL-6) in saliva obtained from patients diagnosed with mild COVID-19, in a diabetic group (DG; n = 10) and a non-diabetic group (NDG; n = 13). All participants were diagnosed with periodontitis, while six participants with periodontitis but not diagnosed with COVID-19 were included as controls.

Results

We found increases in salivary total protein levels in both the DG and NDG compared to control patients. In both groups, salivary CRP and IL-6 levels were comparable. Additionally, the levels of salivary CRP were significantly correlated with total proteins, in which a strong and moderate positive correlation was found between DG and NDG, respectively. A linear positive correlation was also noted in the relationship between salivary IL-6 level and total proteins, but the correlation was not significant. Interestingly, the association between salivary CRP and IL-6 levels was positive. However, a moderately significant correlation was only found in COVID-19 patients with diabetes, through which the association was validated by a receiver operating curve.

Conclusions

These finding suggest that salivary CRP and IL-6 are particularly relevant as potential non-invasive biomarker for predicting diabetes risk in mild cases of COVID-19 accompanied with periodontitis.

Oxytocin as a transdiagnostic biomarker of well-being in severe mental illness during the Covid-19 pandemic

Individuals with severe mental illness (SMI) have been found to suffer a greater decline in psychological well-being compared to the general population in times of stress. The present study aimed to examine clinical and endocrine resilience factors of psychological well-being in SMI patients during the Covid-19 pandemic.

METHODS

After Covid-19 crisis outburst in Israel 112 participants, 69 outpatients, and 43 inpatients and day treatment patients were recruited. Outpatients signed an online informed consent and filled in questionnaires regarding their level of mental health symptoms (OQ-45), fear of Covid-19 (FCV), and psychological well-being (PWB). Inpatients answered the same questionnaires and in addition, went through a positive social interaction paradigm while providing three saliva samples to measure their s-IgA and oxytocin (OT) levels.

RESULTS

A strong negative correlation was found in the whole sample between reported mental health symptoms, fear of Covid-19, and well-being. Hierarchical regression did not find additional contribution of the fear of the pandemic in predicting well-being beyond the impact of symptomatology. For inpatients (N = 39) only, hierarchical regression found that oxytocin, but not s-IgA could explain 5% of the variance of well-being (R2 = 0.05) in individuals with SMI regardless of their mental health symptoms (R2 = 0.46) and their marital status (R2 = 0.21).

CONCLUSIONS

OT is suggested as a possible independent biological resilience factor of well-being in times of major stress among SMI patients. It is still unknown whether OT is a mediator that contributes to well-being or a biological marker that indicates the degree of beneficial social interactions.

Symptomatic Irreversible Pulpitis Induces Increased Levels of Human NLRP3 in Gingival Crevicular Fluid Compared to Saliva: A Case Control Observational Study

INTRODUCTION

The goal of this case-control observational study was to compare the levels of the human nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing-3 (NLRP3) protein in the saliva and gingival crevicular fluid (GCF) of patients with symptomatic irreversible pulpitis (SIP) and healthy controls.

METHODS

The 16 patients in the control group were matched with the 16 patients in the SIP group to create a total of 32 patients. In addition to saliva, GCF (n = 48) samples were collected from the involved tooth (n = 16), contralateral tooth (n = 16), and adjacent tooth (n = 16) in the SIP group. Saliva and GCF were taken from the healthy group as a baseline. An independent t-test was used for statistical analysis. The random-intercept model was used to compare the average NLRP3 levels in the SIP tooth, adjacent tooth, and contralateral tooth taking age as a covariate, and the P value was adjusted using Bonferroni correction.

RESULTS

There were significantly higher levels of NLRP3 in the saliva of SIP patients (1.78 ± 1.14 ng/ml) compared to the healthy control (0.70 ± 0.70 ng/ml) and in the GCF of the involved tooth (5.72 ± 0.63 ng/ml) compared to healthy people (1.60 ± 0.42 ng/ml) (P < .001). In SIP patients the mean difference of NLRP3 levels between SIP and contralateral teeth was significant at 4.13 ng/ml (95% confidence interval, 3.52-4.70 P < .001) and a mean difference between adjacent teeth and contralateral teeth was significant at 3.53 ng/ml [95% confidence interval, 2.94-4.12 P < .001]. The NLRP3 in GCF and saliva had a negative association in the affected tooth but a negligible correlation in healthy controls.

CONCLUSION

The NLRP3 inflammasome has the potential to be employed as a molecular diagnostic biomarker for pulpal disorders.

Salivary biomarkers to evaluate psychological disorders in oral lichen planus: A systematic review with meta-analysis

OBJECTIVE

To analyze the use of salivary biomarkers to identify psychological disorders (anxiety, depression, and stress) in individuals with oral lichen planus (OLP).

MATERIALS AND METHODS

The search was made in Medline/Pubmed, Scopus, Web of Science, Virtual Health Library, ProQuest, and by cross-reference. Original case-control, cross-sectional, and cohort studies, in human subjects (age ≥18 years) with clinical and histopathological diagnosis, with or without the use of psychometric scales, published until June 2021, were included. Random-effects meta-analyses, subgroup analyses, and sensitivity were performed. Publication bias was measured using the Egger test and visual inspection of the funnel plot.

RESULTS

A total of 67 articles were found, of which 12 were included in the meta-analysis. Among the different biomarkers identified, it was only possible to perform a meta-analysis for cortisol. The mean difference between salivary cortisol levels in patients with OLP compared to controls was 3.43 ng/ml (95% CI: 1.20-5.65) with I2  = 98.9%. Studies considered outliers were removed and based on sensitivity analyses, results did not change, therefore, being stable.

CONCLUSION

The studies analyzed demonstrated that cortisol was the most quantified biomarker to identify psychological disorders; however, DHEA, IgA, adiponectin, and α-amylase were also evaluated.

Salivary secretory immunoglobulin A as a potential biomarker of psychosocial stress response during the first stages of life: A systematic review

Mucosal secretory immunoglobulin A (s-IgA) has been recognized as a key component of human first line defense against infection. However, its reactivity to psychosocial stressors is poorly understood. This systematic review aimed to explore whether s-IgA levels changed after psychosocial stress in subjects under the age of 18. Fifteen articles were included. s-IgA basal levels are increased in children older than 9 years old exposed to stress. Furthermore, s-IgA seems to follow a circadian rhythm, which is altered under stress conditions. Finally, the collective evidence suggests that salivary s-IgA rapidly increases under acute stress after puberty. Overall, our review indicates that s-IgA could be considered a potential psychosocial stress biomarker of interest for pediatric and child-juvenile psychiatric population. Further studies are needed to validate the role of s-IgA circadian rhythm and basal levels as psychosocial stress biomarkers and disentangle the role of age and type of stressor.

Immediate and Delayed Salivary Cytokine Responses during Repeated Exposures to Cold Pressor Stress

INTRODUCTION

Excessive stress is increasingly recognized as an important trigger of many diseases prevalent in modern societies, and monitoring such stress-related effects could aid prevention. The measurement of salivary markers of inflammation is emerging as a promising tool to non-invasively quantify stress' effects on immune processes in everyday life and thereby detect early aberrations before the manifestation of serious health problems. However, more laboratory-controlled research is needed in order to establish the timescale and determinants of salivary cytokine responses to acute stress.

METHODS

We repeatedly exposed participants to Cold Pressor Stress Test (CPT) or a control procedure and measured a wide array of salivary cytokines as well as subjective, cardiovascular, and cortisol stress reactions. CPT exposure was repeated every 15 min, 3 times in total, with a duration of 3 min each. Saliva was sampled immediately after the first two exposures as well as in 15-min intervals until 60 min after the onset of the first intervention.

RESULTS

We found that many cytokines were detectable in saliva. Specific stress effects were limited to IL-8 and IL-6, however, which decreased immediately or 15 min after stress onset, respectively. Moreover, IL-8 was negatively correlated to cortisol output in the stress but not in the control group. Significant increases were also observed in salivary TNFα and IFNγ; however, these effects were similar under both stress and control conditions.

DISCUSSION

Our results show that particular salivary cytokines may be sensitive to immediate effects of acute CPT-induced stress and also highlight the importance of employing control procedures to discern stress effects from unrelated variations in salivary cytokines.

The association between the cortisol and cortisone awakening responses

The cortisol awakening response (CAR) is often assessed in the saliva and considered to be representative of serum cortisol. However, free cortisol is rapidly converted into cortisone as it passes from the serum into the saliva. Because of this enzymatic conversion, the salivary cortisone awakening response (EAR) may be more closely related to serum cortisol dynamics than the salivary CAR. Therefore, the purpose of this study was to measure the EAR and CAR in saliva and compare it to the serum CAR.

METHODS

Male participants (n = 12) had an intravenous catheter placed for serial serum sampling and completed two overnight laboratory sessions, wherein participants slept in the laboratory and saliva and serum samples were collected every 15 min after volitional awakening the following morning. Serum was assayed for total cortisol and saliva for cortisol and cortisone. The CAR and EAR was assessed in saliva and the CAR in serum via mixed-effects growth models and common awakening response indices (area under the curve [AUC] relative to the ground [AUC_G] and relative to the increase [AUC_I], and change scores [Δ]).

RESULTS

There was a distinct rise in salivary cortisone following awakening demonstrating the presence of a discernable EAR (β_Quadratic = -41.18, [95%CI = -68.90 to -13.46], p < 0.004, Conditional R² = 0.641). Two EAR indices (AUC_G: p < 0.001 and AUC_I: p = 0.030) were associated with the corresponding serum CAR indices.

CONCLUSION

We demonstrate for the first time a distinct cortisone awakening response. The results suggest the EAR may be more closely related to serum cortisol dynamics during the post-awakening period, and thus, may be a biomarker of interest in addition to the CAR for assessing hypothalamic-pituitary-adrenal axis functioning.

Translational research into frailty from bench to bedside: Salivary biomarkers for inflammaging

Frailty is a complex physiological syndrome associated with adverse ageing and decreased physiological reserves. Frailty leads to cognitive and physical disability and is a significant cause of morbidity, mortality and economic costs. The underlying cause of frailty is multifaceted, including immunosenescence and inflammaging, changes in microbiota and metabolic dysfunction. Currently, salivary biomarkers are used as early predictors for some clinical diseases, contributing to the effective prevention and treatment of diseases, including frailty. Sample collection for salivary analysis is non-invasive and simple, which are paramount factors for testing in the vulnerable frail population. The aim of this review is to describe the current knowledge on the association between frailty and the inflammatory process and discuss methods to identify putative biomarkers in salivary fluids to predict this syndrome. This study describes the relationship between i.-inflammatory process and frailty; ii.-infectious, chronic, skeletal, metabolic and cognitive diseases with inflammation and frailty; iii.-inflammatory biomarkers and salivary fluids. There is a limited number of previous studies focusing on the analysis of inflammatory salivary biomarkers and frailty syndrome; hence, the study of salivary fluids as a source for biomarkers is an open area of research with the potential to address the increasing demands for frailty-associated biomarkers.

Psychological Distress Impact of Coronavirus Disease (COVID-19) Outbreak on Three Continents: A Systematic Review and Meta-analysis

BACKGROUND

The dire state of coronavirus disease (COVID-19) outbreak has had a substantial psychological impact on society.

METHODS

A systematic search was performed through Medline, PubMed, Embase, Scopus, and Web of Science, to investigate the impact of the COVID-19 pandemic on the psychological health of individuals in various countries. Subgroup analyses considered gender and classification of countries into three continents of America, Europe, and Asia. Only studies that used the COVID-19 Peritraumatic Distress Index (CPDI) questionnaire as a tool to assess mental distress were included in this meta-analysis. Heterogeneity among studies was assessed by I² statistic, and the random-effects model was utilized to obtain the pooled prevalence.

RESULTS

This pooled analysis included a large data sample of 21 studies consisting of 94,414 participants. The pooled prevalence of the psychological distress during the time of COVID-19 pandemic by CPDI for the continent of Asia was 43% (34.6% mild-to-moderate and 8.4% severe) which was greater than that for Europe (35%; 30% mild-to-moderate and 5% severe) but lower than that for America (64.3%; 45.8% mild to moderate and 18.5% severe). In addition, the prevalence of psychological distress according to CPDI was higher in females (48%; 40% mild to moderate, 13% severe) compared with males (59%; 36% mild to moderate and 5% severe).

CONCLUSIONS

Our findings suggest that psychological distress in the Americas is a larger problem than in Asia and European continents. Females appear to be more vulnerable and may therefore require further attention in terms of preventive and management strategies. Implementation of both digital and molecular biomarkers is encouraged to increase objectivity and accuracy of assessing the dynamic changes in mental health in the current and future pandemics.

Validation of a novel method of ultraviolet-induced cutaneous inflammation and its associations with anhedonia

Affective immunology of the skin is a growing area; however, established protocols for measuring individual differences in cutaneous inflammation are lacking. To address this, we present a preliminary validation of Precision Implementation of Minimal Erythema Dose (PI-MED) testing as a method for measuring cutaneous inflammation. PI-MED is a recently adapted protocol, optimized for reproducibility and individual differences research, that uses ultraviolet (UV) light to evoke cutaneous erythema, or inflammatory skin reddening. PI-MED's novel UV dosage schedule produces standardized erythema responses across different skin pigmentation types and shows strong internal consistency within person and good test-retest reliability across 8-10 weeks. In line with predictions, increased PI-MED erythema was associated with heightened anhedonia, across several measures, beyond influences of non-affective covariates. While future work should further refine the dosage schedule for the lightest and darkest skin types, overall, evidence supports PI-MED as a protocol for inducing and measuring individual differences in cutaneous inflammation. Further, PI-MED-induced erythema can expand psychoneuroimmunology research by offering a complementary assessment for general inflammatory tone. This work adds to a growing body of evidence demonstrating a distinct relationship between inflammation and anhedonia.

Early Life Trauma and Social Processing in HIV: The Role of Neuroendocrine Factors and Inflammation

OBJECTIVE

Early life trauma (ELT) and HIV are associated with social processing deficits. In people with HIV (PWH), we examined whether facial emotion identification accuracy differs by ELT and whether neuroendocrine factors including cortisol, oxytocin (OT), and arginine vasopressin, and/or immune system measures play a role in the ELT-performance association.

METHODS

We used secondary data from the placebo condition of a pharmacologic challenge study in PWH. Presence of ELT was measured with the Childhood Trauma Questionnaire (at least moderate experiences of sexual, physical, and/or emotional abuse). Social processing was measured with the Facial Emotion Perception Test (FEPT). Salivary immune system measures and cortisol were sampled across a 5-hour study session. Blood was collected at study session start (12 pm ) to measure OT and arginine vasopressin. We examined the association of ELT with FEPT and five biological moderators (from principal components analysis of 12 biomarkers) of ELT-FEPT associations.

RESULTS

Of 58 PWH (42 men; mean [standard deviation] age = 33.7 [8.9] years), 50% endorsed ELT. ELT-exposed PWH demonstrated lower identification accuracy across all emotional expressions (unstandardized β [ B ] = 0.13; standard error [SE] = 0.05; p = .021, d = 0.63) and had higher OT levels compared with ELT-unexposed PWH ( t(1,56) = 2.12, p = .039; d = 0.57). For total accuracy, an OT/C-reactive protein factor moderated the ELT-FEPT association ( B = 0.14; SE = 0.05; p = .014); accuracy was lower in ELT-exposed PWH versus ELT-unexposed PWH when the factor was low but not when high. Similar results were obtained for fearful, neutral, and happy faces ( p values < .05). Regardless of ELT, a myeloid migration (MCP-1/MMP-9) factor was associated with reduced accuracy ( p values < .05).

CONCLUSIONS

Our pilot findings suggest that ELT may alter social processing in PWH, and OT and C-reactive protein may be a target for improving social processing in ELT-exposed PWH, and myeloid migration markers may be a target in PWH more generally.

The Immunological and Hormonal Responses to Competitive Match-Play in Elite Soccer Players

This study aimed to examine the salivary immunoglobulin A (s-IgA) and salivary cortisol (s-Cort) responses to competitive matches in elite male soccer players. Data were collected for 19 players (mean ± SD, age: 26 ± 4 years; weight: 80.5 ± 8.1 kg; height: 1.83 ± 0.07 m; body-fat 10.8 ± 0.7%) from a Russian Premier League team throughout a 6-week period during the 2021-2022 season. Physical match loads were measured through an optical tracking system. s-IgA and s-Cort were assessed one day before each match (MD - 1), 60-min before kick-off, 30-min post-match, and 48-h post-match (MD + 2). At 60-min before kick-off, s-IgA values were lower than at MD - 1 (90% CI difference 15.7-71.3 μg/mL). Additionally, compared to 60-min before kick-off, s-IgA was higher at 30-min post-match (90% CI difference 1.8-57.8 μg/mL) and at MD + 2 (90% CI difference 5.4-60.5 μg/mL). At 30-min post-match, s-Cort was higher than at 60-min before kick-off (90% CI difference 4.84-7.86 ng/mL), while on MD + 2 s-Cort was higher than at 60-min before kick-off (90% CI difference 0.76-3.72 ng/mL). Mixed model regressions revealed that longer playing time and total distance covered, and higher number of high-intensity accelerations, involved smaller s-IgA differences between 30-min post-match and 60-min before kick-off, and between 60-min before kick-off and MD + 2. Additionally, greater high-intensity and sprint distances, and a higher number of high-intensity and maximal accelerations, involved smaller s-Cort differences between 60-min before kick-off and MD + 2. In conclusion, the present results demonstrate that using salivary monitoring combined with match load may be a useful tool to monitor individual mucosal immunity and hormonal responses to match-play and the subsequent recovery periods in elite soccer players.

Expression of salivary immunoglobulins and their association with analgesic neuropeptide opiorphin in anorexia nervosa during adolescence

BACKGROUND

Patients who suffer from anorexia nervosa (AN) are characterized by exceedingly lower body weight, micro- and macro-nutrient deficiencies, and hyposalivation as compared to healthy subjects. In addition, AN may predispose to difficulties in oral health maintenance. However, little is known about the relationship between stress-dependent salivary neuro/immunopeptidergic biomarkers such as opiorphin and immunoglobulins (Ig) and AN.The aim of this case-control study was to evaluate salivary opiorphin and immunoglobulins in female children and adolescents diagnosed with AN compared to healthy controls.

METHODS

Adolescent patients with clinically-confirmed severe restrictive subtype AN (Body Mass Index BMI < 15 kg/m², mean age 15.0 ± 1.8, n = 83) were examined in the first week of hospital admission and compared to healthy matched controls (n = 79). Measurements of salivary opiorphin, IgA, IgG, IgM (ELISA technique), and oral hygiene levels (Plaque Control Record index-PCR) were performed.

RESULTS

In the AN group, a significantly higher concentration of opiorphin was evidenced (3.1 ± 4.1 ng/ml) compared to the control group (1.1 ± 1.2 ng/ml), (p < 0.001), contrary to IgM, which was significantly lower (311.0 ± 185.3 ng/ml) than in the control group (421.2 ± 168.1 ng/ml), (p < 0.001). There were no significant differences in the levels of IgA and IgG, despite a higher concentration of IgA in the AN group vs. controls (p = 0.14). Spearman analysis revealed a correlation between opiorphin and age (p < 0.05), but also with all immunoglobulins IgA, IgG, IgM (p = 0.006, p < 0.001, p < 0.001). Similarly a correlation was found between PCR index and immunoglobulins IgG, IgM (respectively p = 0.028, p < 0.001), and between body mass, BMI, IBW% and IgA, IgM (all p < 0.05).

CONCLUSIONS

In the acute phase of AN, salivary changes in opiorphin and immunoglobulins related to dental plaque suggest an essential role in oral health balance. Changes related to AN may affect the anti-inflammatory and analgesic components of saliva and suggest their use as neurobiological markers in severe malnutrition.

Neuroendocrine Response and State Anxiety Due to Psychosocial Stress Decrease after a Training with Subject's Own (but Not Another) Virtual Body: An RCT Study

Previous research involving healthy participants has reported that seeing a moving virtual body from the first person perspective induces the illusion of ownership and agency over that virtual body. When a person is sitting and the virtual body runs, it is possible to measure physiological, behavioral and cognitive reactions that are comparable to those that occur during actual movement. Capitalizing on this evidence, we hypothesized that virtual training could also induce neuroendocrine effects that prompt a decreased psychosocial stress response, as occurs after physical training. While sitting, 26 healthy young adults watched a virtual avatar running for 30 min from the first person perspective (experimental group), while another 26 participants watched the virtual body from the third person perspective (control group). We found a decreased salivary alpha-amylase concentration (a biomarker for the stress response) after the virtual training among the experimental group only, as well as a decreased subjective feeling of state anxiety (but no difference in heart rate). We argue that the virtual illusion of a moving body from the first person perspective can initiate a cascade of events, from the perception of the visual illusion to physiological activation that triggers other biological effects, such as the neuroendocrine stress response.

Comparison of C-Reactive Protein in Dried Blood Spots and Saliva of Healthy Adolescents

Background/Aim

Determining C-reactive protein (CRP) by non-invasive methods is of great interest for research addressing inflammation in young people. However, direct comparisons of such methods applied in children and adolescents are lacking so far. This study aimed to evaluate the association between CRP measured in dried blood spots (DBS CRP) and in saliva (sCRP), two less invasive alternatives to venipuncture, in 12- to 14-year-old adolescents. To evaluate the validity of both measurements in the context of biobehavioral studies, the potential of DBS CRP and sCRP to discriminate between defined BMI subgroups was assessed.

Materials and Methods

CRP levels in DBS and saliva collected from 87 healthy adolescents (M = 13.25 years, SD = 0.30, 51.7% females) were determined using high sensitive CRP ELISA for serum and salivary CRP ELISA, respectively. Characteristics and correlation of both measurements were assessed for the total sample and for three subgroups classified by BMI percentile ranges (A: ≤ 25; B: 26–74; C: ≥ 75).

Results

In the total sample, DBS CRP and sCRP were significantly associated (r = 0.59, p < 0.001). Splitting the sample into BMI-dependent subgroups revealed similarly strong associations of DBS CRP with sCRP for all three groups (A: r = 0.51; B: r = 0.61; C: r = 0.53). However, comparing the mean CRP values per BMI subgroup, one-way ANOVA reported significant differences for DBS CRP, but not for sCRP mean values.

Conclusions

The significant correlation of DBS CRP with sCRP was independent of the investigated BMI range groups, yet BMI-dependent distinction was only provided by DBS CRP mean values. Overall, our results suggest that DBS CRP is likely to reflect systemic inflammation more precisely. Salivary CRP can be alternatively determined in studies with adolescents when conditions require it, given the oral health status is assessed. Considering that DBS CRP and sCRP share only 35% of common variance, further studies should examine their specific validity.

Strategies to Limit Cognitive Impairments under Sleep Restriction: Relationship to Stress Biomarkers

Adding relaxation techniques during nap or auditory stimulation of EEG slow oscillation (SO) during nighttime sleep may limit cognitive impairments in sleep-deprived subjects, potentially through alleviating stress-releasing effects. We compared daytime sleepiness, cognitive performances, and salivary stress biomarker responses in 11 volunteers (aged 18–36) who underwent 5 days of sleep restriction (SR, 3 h per night, with 30 min of daily nap) under three successive conditions: control (SR-CT), relaxation techniques added to daily nap (SR-RT), and auditory stimulation of sleep slow oscillations (SO) during nighttime sleep (SR-NS). Test evaluation was performed at baseline (BASE), the fifth day of chronic SR (SR5), and the third and fifth days after sleep recovery (REC3, REC5, respectively). At SR5, less degradation was observed for percentage of commission errors in the executive Go–noGo inhibition task in SR-RT condition compared to SR-CT, and for sleepiness score in SR-NS condition compared both to SR-CT and SR-RT. Beneficial effects of SR-RT and SR-NS were additionally observed on these two parameters and on salivary α-amylase (sAA) at REC3 and REC5. Adding relaxation techniques to naps may help performance in inhibition response, and adding nocturnal auditory stimulation of SO sleep may benefit daytime sleepiness during sleep restriction with persistent effects during recovery. The two strategies activated the autonomic nervous system, as shown by the sAA response.

Using Salivary Biomarkers for Stress Assessment in Offshore Saturation Diving: A Pilot Study

Health monitoring during offshore saturation diving is complicated due to restricted access to the divers, the desire to keep invasive procedures to a minimum, and limited opportunity for laboratory work onboard dive support vessels (DSV). In this pilot study, we examined whether measuring salivary biomarkrers in samples collected by the divers themselves might be a feasible approach to environmental stress assessment. Nine saturation divers were trained in the passive drool method for saliva collection and proceeded to collect samples at nine time points before, during, and after an offshore commercial saturation diving campaign. Samples collected within the hyperbaric living chambers were decompressed and stored frozen at −20°C onboard the DSV until they were shipped to land for analysis. Passive drool samples were collected without loss and assayed for a selection of salivary biomarkers: secretory immunoglobulin A (SIgA), C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukins IL-6, IL-8, IL-1β, as well as cortisol and alpha-amylase. During the bottom phase of the hyperbaric saturation, SIgA, CRP, TNF-α, IL-8 and IL-1β increased significantly, whereas IL-6, cortisol and alpha-amylase were unchanged. All markers returned to pre-dive levels after the divers were decompressed back to surface pressure. We conclude that salivary biomarker analysis may be a feasible approach to stress assessment in offshore saturation diving. The results of our pilot test are consonant with an activation of the sympathetic nervous system related to systemic inflammation during hyperbaric and hyperoxic saturation.

The levels of soluble urokinase plasminogen activator receptor (suPAR) in saliva are influenced by acute stress

Although elevations in systemic suPAR levels have been associated with inflammatory conditions and with exposure to life stress and adversity, it is not yet clear whether acute psychological stress influences suPAR levels, either systemically and/or in saliva. The aim of this study was to investigate whether salivary suPAR levels are increased following exposure to acute psychological stress. Healthy subjects, aged 18-40 years, completed a laboratory psychological stressor and provided saliva samples before and after the stress test (60 min apart). Levels of suPAR as well as those of cytokines increased in the post-stress samples (all ps < .001). Baseline and post-stress IL-1β and TNF-α as well as post-stress IL-6 correlated significantly with suPAR (all ps < .01), but IL-10 and baseline IL-6 did not. These results show that suPAR levels in saliva are stress-reactive and suggest a potential application as stress biomarkers in saliva, particularly given the advantage of easily detectable concentrations.

Response of salivary biomarkers to an empathy triggering film sequence-a pilot study

Empathy is a multifaceted phenomenon that is difficult to measure. Self-report questionnaires are the most common and well-validated measures while currently no validated protein biomarkers associated with the empathic reaction have been established. Trigger films have been previously used in psychological research to evoke emotions. Thus, in the present randomized cross-over study we investigated the responses of nine salivary biomarkers that have been related to emotions and stress following an empathy triggering and a control film sequence. Additionally, questionnaires for empathy (Saarbrucken Personality Questionnaire (SPQ)) and current mental stress were applied and participants were asked to assess the film protagonists’ emotions using the Positive and Negative Affect Schedule. Data from 46 participants were included in the analysis. α-Amylase, IgA, IL-1β and estradiol showed a significantly different response between the empathy and control intervention. Moreover, normalized levels of these biomarkers significantly correlated with single scales of the SPQ (control film sequence: α-amylase and IgA with personal distress; estradiol with empathic concern; IL-1β with fantasy; empathy triggering film sequence: IgA with empathic concern, fantasy and the total empathy score). These findings indicated that the observed changes in salivary biomarker levels were reflective of a physiological response to the empathy triggering film sequence. Future studies using different triggers and settings will show if the identified biomarkers can be considered as surrogate markers for empathic reactions in general.

Social dialogue triggers biobehavioral synchrony of partners' endocrine response via sex-specific, hormone-specific, attachment-specific mechanisms

Social contact is known to impact the partners' physiology and behavior but the mechanisms underpinning such inter-partner influences are far from clear. Guided by the biobehavioral synchrony conceptual frame, we examined how social dialogue shapes the partners' multi-system endocrine response as mediated by behavioral synchrony. To address sex-specific, hormone-specific, attachment-specific mechanisms, we recruited 82 man–woman pairs (N = 164 participants) in three attachment groups; long-term couples (n = 29), best friends (n = 26), and ingroup strangers (n = 27). We used salivary measures of oxytocin (OT), cortisol (CT), testosterone (T), and secretory immuglobolinA (s-IgA), biomarker of the immune system, before and after a 30-min social dialogue. Dialogue increased oxytocin and reduced cortisol and testosterone. Cross-person cross-hormone influences indicated that dialogue carries distinct effects on women and men as mediated by social behavior and attachment status. Men's baseline stress-related biomarkers showed both direct hormone-to-hormone associations and, via attachment status and behavioral synchrony, impacted women's post-dialogue biomarkers of stress, affiliation, and immunity. In contrast, women's baseline stress biomarkers linked with men's stress response only through the mediating role of behavioral synchrony. As to affiliation biomarkers, men's initial OT impacted women's OT response only through behavioral synchrony, whereas women's baseline OT was directly related to men's post-dialogue OT levels. Findings pinpoint the neuroendocrine advantage of social dialogue, suggest that women are more sensitive to signs of men's initial stress and social status, and describe behavior-based mechanisms by which human attachments create a coupled biology toward greater well-being and resilience.

Pentraxin-3 detected in human saliva shows limited correlation with biomarkers associated with systemic inflammation

Pentraxin-3 (PTX3) is a conserved protein of the innate immune system which has been less studied than the pentraxin C-reactive protein (CRP), but it is of relevance in, for example, vascular pathology and pregnancy morbidities. Since the interest in salivary biomarkers in general is increasing, we asked whether PTX3 could be detected in saliva and if any substantial diurnal variation occurs. In addition, we evaluated association with biomarkers of systemic inflammation (interleukin (IL)-1β, IL-6, and IL-8 and CRP), body mass index (BMI), smoking, and age. PTX3 in morning and evening saliva from 106 middle-aged participants of the general population was investigated by ELISA and total protein levels by spectrophotometry. PTX3 was detectable in saliva, and concentrations varied over the day with higher morning concentrations, but the PTX3 relative protein levels (percentage of total protein) were significantly higher in the evening. Sex and age did not impact salivary PTX3, but smoking was associated with lower PTX3 levels. BMI correlated positively with PTX3 in evening saliva. There was no general association with biomarkers of systemic inflammation, except for IL-6. Salivary PTX3 likely reflects the local inflammatory milieu, and adjustments for sampling time, smoking habits, and BMI are needed to adequately interpret PTX3 in saliva.

Resistance training as an acute stressor in healthy young men: associations with heart rate variability, alpha-amylase, and cortisol levels

Regular resistance training has been shown to have many physiological and psychological health benefits. However, the underlying physiological processes are not yet fully understood. One explanation is that resistance training acts like an acute stressor and modulates physiological pathways that are associated with the stress response such as the sympathetic nervous system (SNS), the parasympathetic nervous system (PNS), and the hypothalamic-pituitary-adrenal (HPA) axis. This was systematically investigated in our study. Participants were 45 healthy men who had been doing resistance training regularly for at least nine months. Salivary α-amylase and heart rate that were used as markers for SNS activity increased during the training and decreased afterwards. PNS activity that was assessed by means of heart rate variability parameters decreased during the training and increased after it. Salivary cortisol that was used as marker for HPA axis activity decreased throughout the session. Furthermore, an improvement of positive affect was found after the training. However, additional analyses indicated that the physiological response patterns were found for participants who chose upper-body exercises (in contrast to lower-body exercises) only. Therefore, we were able to show that an upper-body resistance training acts partially like an acute stressor which leads to the typical SNS and PNS - but not HPA axis - stress responses. We conclude that resistance trainings might be an alternative to classical relaxation programs which would have the additional advantage that it is a physical training at the same time. However, more research is needed to develop specific trainings which entirely fulfill this goal.

Measuring salivary markers of inflammation in health research: A review of methodological considerations and best practices

There is an increasing interest in using saliva to measure inflammatory biomarkers. Compared to blood, saliva is non-invasive, requires a lower biosafety classification, and requires less specialized personnel to collect. As the assessment of inflammation in saliva becomes more popular in psychoneuroimmunology research, the development of gold-standard methodological practices is paramount. This paper reviews different considerations for designing studies to assess salivary measures of inflammation. We review saliva collection procedures, sample storage and processing considerations, assay techniques, flow rate, correspondence with blood-based markers, and potential demographic and health moderators of levels of salivary markers of inflammation. Together, this review highlights critical gaps for future research, including calls for standardization of study protocols, transparent reporting of results, assessing predictive validity of markers of salivary inflammation for disease, and the need for assessment of participants' oral and general health status. Although additional work is needed to elucidate gold standards for study design, measurement, and analysis, salivary markers of inflammation may be a useful tool for understanding oral and peripheral inflammation dynamics non-invasively.

Immunosenescence in Testicular Cancer Survivors: Potential Implications of Cancer Therapies and Psychological Distress

Testicular cancer (TC) is the most frequent solid tumor diagnosed in young adult males. Although it is a curable tumor, it is frequently associated with considerable short-term and long-term morbidity. Both biological and psychological stress experienced during cancer therapy may be responsible for stimulating molecular processes that induce premature aging and deterioration of immune system (immunosenescence) in TC survivors, leading to an increased susceptibility to infections, cancer, and autoimmune diseases. Immunosenescence is a remodeling of immune cell populations with inversion of the CD4:CD8 ratio, accumulation of highly differentiated memory cells, shrinkage of telomeres, shift of T-cell response to Th2 type, and release of pro-inflammatory signals. TC survivors exposed to chemotherapy show features of immunological aging, including an increase in memory T-cells (CD4+ and CD8+) and high expression of the senescence biomarker p16INK4a in CD3+ lymphocytes. However, the plethora of factors involved in the premature aging of TC survivors make the situation more complex if we also take into account the psychological stress and hormonal changes experienced by patients, as well as the high-dose chemotherapy and hematopoietic stem cell transplantation that some individuals may be required to undergo. The relatively young age and the long life expectancy of TC patients bear witness to the importance of improving quality of life and of alleviating long-term side-effects of cancer treatments. Within this context, the present review takes an in-depth look at the molecular mechanisms of immunosenescence, describing experimental evidence of cancer survivor aging and highlighting the interconnected relationship between the many factors modulating the aging of the immune system of TC survivors.

Pronounced Diurnal Pattern of Salivary C-Reactive Protein (CRP) With Modest Associations to Circulating CRP Levels

C-reactive protein (CRP), a humoral component of the innate immune system with important functions in host-defense, is extensively used as a sensitive biomarker of systemic inflammation. During inflammation, hepatocyte-derived CRP rises dramatically in the blood due to increased interleukin-6 (IL-6) levels. Reliable detection of CRP in saliva, instead of blood, would offer advantages regarding sampling procedure and availability but using saliva as a diagnostic body fluid comes with challenges. The aims of this study were to evaluate associations between salivary CRP, total protein levels in saliva and serum CRP. Furthermore, we examined associations with plasma IL-6, body mass index (BMI), tobacco smoking and age. Salivary CRP was investigated by ELISA in 107 middle-aged participants from the general population. We employed spectrophotometric determination of total protein levels. Correlation analyses were used for associations of salivary CRP with serum CRP (turbidimetry), plasma IL-6 (Luminex^®), BMI and smoking habits. Salivary median CRP was 68% higher (p=0.009), and total protein levels were 167% higher (p<0.0001), in morning compared to evening saliva. The correlation coefficients between serum and salivary CRP were low to moderate, but stronger for evening than morning saliva. Plasma IL-6 correlated significantly with serum CRP (r_s=0.41, p<0.01), but not with morning or evening salivary CRP. Non-smokers showed 103% higher salivary CRP levels (p=0.015), whereas serum CRP was independent of smoking status. As opposed to CRP in serum, salivary CRP was not associated with BMI. Salivary CRP was 90% higher among the age interval 60–69 years compared to subjects aged 45–59 (p=0.02) while serum CRP levels did not differ between the age groups. In conclusion, CRP in saliva did not straightforwardly reflect serum concentrations. This raises questions regarding adequate reflection of biological events. The pronounced diurnal salivary CRP pattern accentuates the importance of standardizing the time-point of sampling.

Depression, Anxiety, and Stress Among Patients with COVID-19: A Cross-Sectional Study

AIM

Patients with confirmed COVID-19 infection can develop several psychological consequences. Epidemiological data on mental health and psychological disorder inpatients infected with COVID-19 pneumonia are not available in Iranian patients. The purpose of this study was to evaluate the anxiety, stress, and depression of patients with COVID-19.

MATERIAL AND METHODS

This cross-sectional survey was conducted in 2020. All confirmed patients with COVID-19 were included in the study by census sampling. Assessment of depression, stress, and anxiety was performed using the DASS-21 questionnaire. All statistical analyses were performed using R version 3.5.1.

RESULTS

The questionnaires were completed by 221 patients with COVID-19 infection (204 males, 17 females). The mean age was 45.90 ± 7.73 years. Our results indicated that the mean scores of depression and anxiety were at "extremely severe" levels, while stress levels were "severe." The prevalence of "extremely severe" symptoms of depression and anxiety was 54.29% and 97.29%, respectively. The prevalence of severe stress was 46.61%.

CONCLUSION

In this study, patients infected with COVID-19 reported severe and extremely severe experience psychological distress. Further studies should focus on the combined use of psychological and molecular biomarker testing to increase accuracy. Overall, the findings demonstrate the necessity of special intervention programs for the confirmed patients with emerging infectious disease COVID-19 to promote mental health needs.

Salivary free light chains as a new biomarker to measure psychological stress: the impact of a university exam period on salivary immunoglobulins, cortisol, DHEA and symptoms of infection

INTRODUCTION

Measurement of immunoglobulin free light chains (FLCs) in saliva can serve as a non-invasive biomarker in health and behavioural research. FLCs have been explored in relation to physiological stress but FLC responses to psychological stress and their relationship with infections remain unknown. This study aimed to investigate the impact of exam period stress on salivary FLCs alongside other established biomarkers of stress and whether FLCs relate to symptoms of infection.

METHODS

58 healthy adults studying at university completed saliva samples and questionnaires in a period without exams (baseline), and again prior to the start of an exam period. Saliva samples were assessed for FLCs, IgA, cortisol and dehydroepiandrosterone (DHEA). Measures of life events stress, perceived stress, anxiety and depression were completed. Students also reported incidence and severity of symptoms of infection and rated general well-being at baseline, prior to, during and after the exam period. Exercise, sleep and alcohol consumption were also assessed at both timepoints.

RESULTS

FLCs secretion rates were significantly lower at the exam period compared to baseline (p < .01), with reductions of 26% and 25% for κ FLC and λ FLC, respectively. In agreement, salivary IgA secretion rate was lower at exams (non-significant trend, p = .07). Cortisol concentration significantly increased at exams (p < .05) while DHEA did not change, leading to an increase in the cortisol:DHEA ratio (p = .06). Depression (p < .05) and anxiety increased from baseline to exams and life stress reported in the build up to the exam period was higher compared with baseline (p < .001). Well-being significantly decreased from baseline to exams (p < .01). The proportion of participants reporting infection symptoms (70%) was unchanged between baseline and prior to exams. No significant relationships were found between FLCs or other saliva parameters and infection symptoms, well-being or stress/psychological measures. Changes in saliva parameters between timepoints were independent of health behaviours.

CONCLUSIONS

Salivary FLCs are responsive to life events stress and corroborate with IgA. This preliminary study highlights the potential utility of FLCs as a new salivary biomarker in stress research.

Salivary Stress/Immunological Markers in Crohn's Disease and Ulcerative Colitis

There is continuous and growing interest in research into new alternatives to standard biomarkers to detect and follow-up disease, reducing physical and psychological stress in patients needing regular and invasive medical examinations for the evaluation of pathologies, including inflammatory bowel diseases (IBD). Saliva is one of the most promising body fluids in the research of new biomarkers, thanks to the large number of molecules it contains. Many molecules present in saliva are often directly correlated to their concentration in the blood but may be affected by the condition of the oral cavity. This means that a careful selection of a specific biomarker is required for each pathology, especially pathologies such as IBD, which may induce inflammation in the oral cavity. Here, we analyze the currently used and the proposed new salivary biomarkers (i.e., calprotectin, cytokines, IgA, cortisol, and oxidative stress markers) for the detection and follow-up of the main subtypes of IBD, known as ulcerative colitis and Crohn's disease.

Body Fluid Biomarkers for Alzheimer's Disease-An Up-To-Date Overview

Neurodegeneration is a highly complex process which is associated with a variety of molecular mechanisms related to ageing. Among neurodegenerative disorders, Alzheimer's disease (AD) is the most common, affecting more than 45 million individuals. The underlying mechanisms involve amyloid plaques and neurofibrillary tangles (NFTs) deposition, which will subsequently lead to oxidative stress, chronic neuroinflammation, neuron dysfunction, and neurodegeneration. The current diagnosis methods are still limited in regard to the possibility of the accurate and early detection of the diseases. Therefore, research has shifted towards the identification of novel biomarkers and matrices as biomarker sources, beyond amyloid-β and tau protein levels within the cerebrospinal fluid (CSF), that could improve AD diagnosis. In this context, the aim of this paper is to provide an overview of both conventional and novel biomarkers for AD found within body fluids, including CSF, blood, saliva, urine, tears, and olfactory fluids.

The effect of acute stress on salivary markers of inflammation: A systematic review and meta-analysis

BACKGROUND

Salivary biomarkers of inflammation are increasingly used in stress research. This systematic review and meta-analysis provides a quantitative summary of changes in salivary inflammatory markers in response to acute stress.

METHOD

The review included 1558 participants (42 unique samples, 33 studies) obtained through electronic databases (PubMed, PsycINFO, Embase), reference treeing, and articles identified by a 2015 review on a similar topic. To be eligible, articles had to be quantitative and assess change in at least one biomarker of salivary inflammation in response to acute stress in adults. The primary outcome was magnitude of change in inflammatory biomarkers (Cohen's d for repeated measures [d_av]).

RESULTS

Measures of salivary inflammation included: C-reactive protein (CRP), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IL-18, IL-21, interferon (IFN)-α, IFN-γ, and tumor necrosis factor (TNF)-α. Cytokines IL-6 (k = 26, d_av = 0.27), IL-10 (k = 11, d_av = 0.34), TNF-α (k = 10, d_av = 0.57), and IFN-γ (k = 6, d_av = 0.28) significantly increased in response to stress. Post hoc sensitivity analyses revealed that IL-1β (k = 19, d_av = 0.16) and IL-8 (k = 7, d_av = 0.30) also increased from pre- to post-stress, but findings with IFN-γ did not hold after removing one outlier study. Examination of moderators suggested that study methodology and sample demographics moderated some associations.

CONCLUSIONS

This meta-analysis revealed that certain salivary inflammatory cytokines increase in response to acute stress. Significant heterogeneity in results and moderator analyses suggest need for standardization of research protocols. Directions for future research are discussed.

Towards On-site Determination of Secretory IgA in Artificial Saliva with Gold-Linked Electrochemical Immunoassay (GLEIA) Using Portable Potentiostat and Disposable Printed Electrode

Mental stress is closely connected with our physical and mental wellness. Therefore, stress measurement can contribute to assess our lifestyle and increase our quality of life. In this paper, we detect the secretory immunoglobulin A (sIgA), which is the candidate of salivary stress markers, with original electrochemical immunoassay: gold-linked electrochemical immunoassay (GLEIA). This biosensor is based on a sandwich-type immunosensor and adopts the electrochemical method to detect the reduction peak from Au nanoparticles linked to the secondary antibody. GLEIA is convenient and cost-effective that only requires a low sample volume (10 μL). In addition, the GLEIA show high sensitivity and selectivity. We obtained the linear response to relate the concentration of sIgA (10-300 ng/mL) in D-PBS buffer with the artificial saliva which includes salivary inorganic salt and typically glycoprotein (mucin). Furthermore, we obtained acceptable selectivity in the various solution with salivary proteins such as α-amylase, human serum albumin, immunoglobulin G (IgG), lysozyme, and mucin. In the future, we try to detect the sIgA in real saliva for on-site stress measurement using GLEIA and to integrate the various immunosensors for stress markers in saliva.

Positive and Negative Affect and Salivary Markers of Inflammation Among Young Adults

BACKGROUND

Emerging evidence suggests that higher circulating levels of inflammatory biomarkers in blood are associated with higher negative affect (NA) and lower positive affect (PA). To our knowledge, the unique associations between NA and PA in daily life and salivary biomarkers of inflammation have not been examined. This study examined these associations in young adults.

METHODS

Measures of NA and PA were created from aggregated daily measures of affect (morning and evening ratings averaged across 14 days). We investigated associations between these measures and salivary C-reactive protein (CRP) and interleukin (IL)-6 in a sample of 108 young adults (60% female, mean age = 20.45 ± 1.47), a subset of whom had self-reported chronic back pain (n = 49). CRP and IL-6 were determined from saliva obtained at the end of the daily diary period.

RESULTS

After covarying for age, gender, body mass index, chronic pain status, salivary flow rate, and NA, higher PA was associated with lower salivary CRP (β = - 0.02, 95% CI (- 0.03, - 0.00) sr2 = .06, p = .01) but not IL-6; removing NA from this model did not change results. In a model with the same covariates (and PA), NA was not significantly related to CRP or IL-6. Chronic back pain status and gender did not moderate results.

CONCLUSIONS

Findings suggest that higher PA may be associated with lower salivary CRP in young adults, even after accounting for NA and demographic characteristics. Findings highlight the utility of assessing emotional states in relation to salivary markers of inflammation in future biobehavioral research.

Remitted depression and cognition in HIV: The role of cortisol and inflammation

In major depressive disorder (MDD) and remitted MDD (rMDD) alterations in cortisol and inflammation are associated with cognitive difficulties, but these relationships have not been investigated in HIV. We used secondary data from a placebo-controlled, cross-over study of cognitive performance following a probe of the hypothalamic-pituitary-adrenal (HPA) axis (low dose hydrocortisone; LDH 10 mg) in 65 people with HIV (PWH; 36 women). Using placebo data, we examined sex-specific associations between two biomarkers - basal afternoon salivary cortisol and salivary inflammatory cytokines - cognition, and rMDD. Salivary cortisol and inflammatory biomarkers were sampled across the 5 -h study. The panel of inflammatory markers included interleukin (IL)-6, IL-8, IL-1β, tumor necrosis factor-(TNF)-α, CRP, interferon gamma-induced protein (IP-10), monocyte chemotactic protein (MCP)-1, monokine induced by interferon (MIG), matrix metalloproteinase MMP-9, and MMP-1. Learning, memory, attention/concentration, and executive function were assessed 30 min and 4 h after the placebo intervention; visuospatial ability was also assessed 30 min after the placebo intervention. For women but not men with HIV, basal cortisol concentrations were higher in rMDD versus noMDD groups, and related to poorer learning and memory. For men and women with HIV, basal inflammatory cytokines were higher in rMDD versus noMDD groups, but were negatively related to cognition independent of rMDD status. Cortisol and cytokines relate to cognition in PWH, but the associations depended on sex, rMDD status, and their interaction.

Printed Organic Transistor-based Biosensors for Non-invasive Sweat Analysis

This review describes recent advances in biosensors for non-invasive human healthcare applications, especially focusing on sweat analysis, along with approaches for fabricating these biosensors based on printed electronics technology. Human sweat contains various kinds of biomarkers. The relationship between a trace amount of sweat biomarkers partially partitioned from blood and diseases has been investigated by omic analysis. Recent progress in wearable or portable biosensors has enabled periodic or continuous monitoring of some sweat biomarkers while supporting the results of the omic analysis. In this review, we particularly focused on a transistor-based biosensor that is highly sensitive in quantitatively detecting the low level of sweat biomarkers. Furthermore, we showed a new approach of flexible hybrid electronics that has been applied to advanced sweat biosensors to realize fully integrated biosensing systems wirelessly connected to a networked IoT system. These technologies are based on uniquely advanced printing techniques that will facilitate mass fabrication of high-performance biosensors at low cost for future smart healthcare.

Validity and reliability evidence of a point of care assessment of salivary cortisol and α-amylase: a pre-registered study

PURPOSE

The iPro Cube is a small portable point-of-care device designed to analyse salivary markers of stress in a user-friendly manner (e.g., fast, convenient). Our aim was to test the reliability and validity of the iPro Cube to measure salivary cortisol and α-amylase as compared to the common laboratory standard method (ELISA immunoassay) prior to and after moderate intensity exercise.

METHODS

The study was a repeated measures, pre-registered design, and statistical framework that incorporated prior knowledge directly into the estimation process. Twenty-nine individuals (age = 27.4 ± 6.6 y; body-mass = 70.8 ± 11.3 kg; height = 1.74 ± 0.92 m; 18 males) completed a single PWC75%HRmax, with repeated measures of salivary cortisol and -amylase pre, immediately post, and 30 min post-exercise.

RESULTS

Correlation between the iPro Cube and laboratory-based assessments of salivary cortisol was moderate-to-large (0.53 > r < 0.81) across all three testing points. In contrast, correlation between the iPro Cube and laboratory-based assessments of -amylase was small-to-moderate (0.25 > r < 0.46). We found a large correlation between duplicate samples of iPro Cube cortisol assessment (0.75 > r < 0.82), and a moderate-to-large correlation for -amylase (0.51> r < 0.77).

CONCLUSIONS

The iPro Cube is capable of taking measures of salivary cortisol that are moderately correlated to values obtained via ELISA immunoassay, however the unit underestimates salivary cortisol and overestimates salivary -amylase at rest and post-moderate intensity exercise. It is recommended that researchers continue using standard laboratory techniques to assess these salivary stress markers.