Is there a link between stress and immune biomarkers and salivary opiorphin in patients with a restrictive-type of anorexia nervosa?

Abstract

Objectives: Opiorphin is a salivary peptide with analgesic and antidepressant properties. Its relationship with the hypothalamic-pituitary-adrenal, autonomic nervous and immune systems may provide understanding of chronic stress, especially in anorexia nervosa (AN). This study investigated a possible correlation between opiorphin and stress/immune biomarkers, cortisol, salivary alpha-amylase (sAA) and secretory immunoglobulin A (sIgA), in saliva of patients with restrictive-type AN.Methods: A case-control clinical trial was conducted in 92 AN patients (+75 healthy controls). Unstimulated salivary samples were taken during the acute stage of AN, measurements of cortisol, sAA, sIgA and opiorphin were performed with a quantitative assay (enzyme-linked immunosorbent assay, P < 0.05).Results: AN patients displayed an increase in cortisol (P < 0.001) and sIgA (P < 0.001) but not in sAA (P = 0.279) levels. Distinct correlation between these two parameters and body-weight indexes were observed. Opiorphin levels were neither correlated to stress and immune biomarkers, nor to salivary flow rate.Conclusions: The effect of stress responses can be reliably assessed in saliva in AN patients. The difference between sIgA and cortisol indicate that they can both be used for mental stress assessment in saliva. Modulation of opiorphin by chronic stress was not confirmed. Unchanged sAA indicates a partial adaptation of human organism to severe condition during malnutrition.

Keywords: Anorexia nervosa; cortisol; opiorphin; saliva; stress.