Both human and animal studies have demonstrated an association between psychological stress and susceptibility to oral infectious diseases. The oral tissues are protected by the salivary secretory proteins, which prevent infection and disease through interference with and regulation of microbial colonization. The secretion and concentration of the salivary proteins is altered by psychological stress. This presents a potential pathway by which stress may affect oral health. Previous studies by our group have demonstrated robust effects of acute forms of psychological stress on salivary protein secretion. Additional experiments showed that the saliva pellicle that is formed by stress induced saliva promotes the in vitro adherence of oral bacteria. Bacterial adherence is a first and essential step in infection. However, acute forms of distress (i.e., minutes to hours) may have very different biological effects than more chronic forms of distress (i.e., days to weeks). Therefore, the objectives of the study proposed here are (a) to examine whether protracted forms of distress also affect parameters of salivary immunity, and (b) to examine whether protracted forms of stress modulate saliva-mediated microbial colonization processes, such as bacterial adherence and aggregation. Specifically, we aim to determine (1) if protracted distress reduces the salivary concentration and secretion rate of components of adaptive secretory immunity, such as Secretory Immunoglobulin A (S-lgA) and the S-lgA subclasses; (2) to determine if protracted distress affects the salivary secretion and concentration of innate protective proteins (e.g., mucin, cystatin); (3) to determine if the saliva-mediated adherence and aggregation of viridans streptococci (as prototypical early colonizers of the dental plaque) is altered in subjects that experience protracted distress. By comparing saliva composition and functions in individuals that report low vs. high levels of depressive symptoms, this study investigates a novel pathway linking stress to oral infectious disease. ? ?
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