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.

Secretory immunoglobulin A (s-IgA) reactivity to acute psychosocial stress in children and adolescents: The influence of pubertal development and history of maltreatment.

BACKGROUND: Mucosal secretory immunoglobulin A (s-IgA) is an antibody protein-complex that plays a crucial role in immune first defense against infection. Although different immune biomarkers have been associated with stress-related psychopathology, s-IgA remains poorly studied, especially in youth. OBJECTIVES: The present study investigated how s-IgA behaves in front of acute psychosocial stress in children and adolescents, including possible variability associated with developmental stage and history of childhood maltreatment (CM). METHODS: 94 children and adolescents from 7 to 17 years (54 with a current psychiatric diagnostic and 40 healthy controls) drawn from a larger Spanish study were explored (EPI-Young Stress Project). To assess biological reactivity, participants provided five saliva samples during an acute laboratory-based psychosocial stressor, the Trier Social Stress Test for Children (TSST-C). Samples were assayed for s-IgA, as well as for cortisol. Pubertal development was ascertained by Tanner stage and CM following TASSCV criteria. RESULTS: We observed s-IgA fluctuations throughout the stressor, indicating the validity of TSST-C to stimulate s-IgA secretion (F(4,199) = 6.200, p <.001). Although s-IgA trajectories followed a reactivity and recovery pattern in adolescents, children exhibited no s-IgA response when faced with stress (F(4,197) = 3.406, p =.010). An interaction was found between s-IgA and CM (F(4,203) = 2.643, p =.035). Interestingly, an interaction between developmental stage, CM history and s-IgA reactivity was identified (F(12,343) = 2.036, p =.017); while children non-exposed to maltreatment exhibited no s-IgA changes to acute stress, children with a history of CM showed a similar response to adolescents, increasing their s-IgA levels after the psychosocial stressor. CONCLUSION: Acute psychosocial stress stimulates s-IgA secretion, but only after puberty. However, children with a history of maltreatment exhibited a response resembling that of adolescents, suggesting an early maturation of the immune system. Further studies are needed to clarify the validity of s-IgA as an acute stress biomarker, including additional measures during stress exposure.

Breast milk oxytocin and s-IgA modulate infant biomarkers and social engagement; The role of maternal anxiety.

Breastfeeding has long been known to improve infants' health and mental development and to enhance the mother-infant bond, but much less research focused on the biological composition of breast milk and its associations with the infant's biomarkers and social development. In this exploratory study, we measured oxytocin (OT) and secretory immunoglobulin-A (s-IgA), the most abundant antibody in breast milk, and evaluated their associations with the same biomarkers in infant saliva and, consequently, with infant social engagement behavior. Fifty-five mother-infant dyads were home-visit and OT and s-IgA were assessed from breast milk and from infant saliva before and after a free-play interaction. Infant social behavior was coded offline using the Coding Interactive Behavior (CIB) and maternal anxiety self-reported. A path model revealed that mother's breast milk s-IgA impacted child social engagement via its links with child OT. In parallel, maternal breast milk OT was linked with infant social behavior through its association with the infant's immunity. This path was moderated by maternal anxiety; only in cases of high anxiety breast milk OT was positively connected to infant s-IgA. Our study, the first to measure OT and s-IgA in both breast milk and infant saliva in relation to observed social behavior, underscores the need for much further research on the dynamic interplay between breast milk composition, infant biomarkers, maternal mental health, and infant social outcomes. Results may suggest that biological systems in breast milk integrate to prepare infants to function in their social ecology through bio-behavioral feedback loops that signal the degree of stress in the environment.

Effect of walnut (Juglans sigillata) oil on intestinal antioxidant, anti-inflammatory, immunity, and gut microbiota modulation in mice.

The study investigated the anti-oxidant, anti-inflammatory, immunity, and gut microbiota modulation in mice (n = 60; 15 mice/group) after intragastric administration of walnut oil (WO; three groups (low (LD), medium (MD), and high doses (HD): 2.5, 5, and 10 ml/kg, respectively) and normal control (NC, saline). WO significantly increased the median villous height/crypt depth (VH/CD) ratio, the activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in intestinal mucosa. WO exerted the anti-inflammatory effects by decreasing the expression of tumor necrosis factor-α (TNF-α) in the duodenal mucosa. All groups shared 157 operational taxonomic units (OTUs; 97% similarity) representing nine phyla. The relative abundance in gut microbiota shifted from more pathogenic bacteria-Helicobacter (NC: 22% versus MD: 3%) toward probiotic-Lactobacillus (NC: 19% versus MD: 40%). The immune organ index (spleen) and contents of secretory immunoglobulin A (S-IgA) were increased from small intestine. In conclusion, WO decreased the oxidative stress, inflammation, and improved the immunity and beneficial gut microbiota in the mice. PRACTICAL APPLICATIONS: Walnut oil (WO) is widely used in traditional medicine around the world and is prescribed as beneficial food oil in agro-industry. However, the intestinal benefits of WO have not been explored extensively, and even its therapeutic mechanism still remains unknown in modern medicine. In this study, WO from Juglans sigillata was investigated for its preventive and protective effects on the intestinal mucosa in mice including anti-oxidant, anti-inflammatory, immunity, and gut microbiota modulation. WO decreased the oxidative stress, inflammation, and improved immunity and beneficial gut microbiota in the mice. WO has shown strong probiotic effect on the gut, and thus, can be considered as a potential candidate in food. The study outcome would enhance utilization of WO for the prevention of gastrointestinal diseases (e.g., Helicobacter, etc.) both in animals and human (inflammatory bowel diseases, IBD) and the formulation of functional foods.

Effect of the Deep Sea Shark-liver Oil Component Food on Secretion Type Immunoglobulin A Density of Saliva in the Normal Man and Woman Adult / 日本補完代替医療学会誌

Secretory immunoglobulin A (s-IgA) in saliva constitutes the first-line barrier to the entry of pathogens into the body, implying its critical role in mucosal immunity.To examine the effect of a shark liver oil (SLO)-containing diet on salivary s-IgA concentration in healthy male and female adults, 42 subjects were assigned to either placebo or 6 weeks of a 2,400 mg SLO-containing diet (1,500 mg as SLO) and assessed in a randomized, double-blind, placebo-controlled, parallel group trial.Salivary s-IgA concentration significantly increased at week 6 in the SLO group (P = 0.033), but not in the placebo group.Moreover, there was a significant difference between groups in the magnitude of change from baseline to week 6.No intervention-related adverse event or abnormal changes of laboratory test parameters were observed throughout the study period.In conclusion, an SLO-containing diet increases salivary s-IgA in healthy adults.