Stress-induced impairments of mucosal immunity may increase susceptibility to infectious diseases. The present study investigated the association of perceived stress, depressive symptoms, and loneliness with salivary levels of secretory immunoglobulin A (S-IgA), the subclasses S-IgA1, S-IgA2, and their transporter molecule Secretory Component (SC). S-IgA/SC, IgA1/SC and IgA2/SC ratios were calculated to assess the differential effects of stress on immunoglobulin transport versus availability.
This study involved 113 university students, in part selected on high scores on the UCLA Loneliness Scale and/or the Beck Depression Inventory. Stress levels were assessed using the Perceived Stress Scale. Unstimulated saliva was collected and analyzed for total S-IgA and its subclasses, as well as SC and total salivary protein. Multiple linear regression analyses, adjusted for gender, age, health behaviors, and concentration effects (total protein) revealed that higher perceived stress was associated with lower levels of IgA1 but not IgA2. Perceived stress, loneliness and depressive symptoms were all associated with lower IgA1/SC ratios. Surprisingly, higher SC levels were associated with loneliness and depressive symptoms, indicative of enhanced transport activity, which explained a lower IgA1/SC ratio (loneliness and depression) and IgA2/SC ratio (depression).
This is the first study to investigate the effects of protracted psychological stress across S-IgA subclasses and its transporter SC. Psychological stress was negatively associated with secretory immunity, specifically IgA1. The lower immunoglobulin/transporter ratio that was associated with higher loneliness and depression suggested a relative immunoglobulin depletion, whereby availability was not keeping up with enhanced transport demand.
In this study, we present a new stochastic volatility model incorporating a flocking mechanism between individual volatilities of assets. Collective phenomena of asset pricing and volatilities in financial markets are often observed; these phenomena are more apparent when the market is in critical situations (market crashes). In the classical Heston model, the constant theoretical mean of the square of the volatility was employed, which can be assumed a priori. Our proposed model does not assume this mean value a priori, we instead use the flocking effect to continuously update the theoretical mean value using the local weighted average of individual volatility values. To perform this function, we use the Cucker–Smale flocking mechanism to calculate the local mean. For some classes of interaction weights such as all-to-all and symmetric coupling with a positive lower bound, we show that the fluctuations of the square process of volatility are uniformly bounded, such that the overall dynamics are mainly dictated by the averaged process. We also provide several numerical examples showing the dynamics of volatility.
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