Analysis of the intestinal IgA response in mice exposed to chronic stress and treated with bovine lactoferrin.

ABSTRACT

Immunoglobulin (Ig) A, an antibody with a pivotal role in gut homeostasis, can be modulated by stress and bovine lactoferrin (bLf). The aim of the present study was to analyze the impact of chronic stress on the IgA response in the small intestine during bLf treatment. Male BALB/c mice (n=6 mice/group) underwent 1 h of chronic stress by immobilization for 7 consecutive days or were left unstressed, and were untreated or treated with bLf (50, 500 or 5,000 µg). Plasma corticosterone expression levels were determined by ELISA. The distal small intestine was dissected to analyze i) total IgA, secretory IgA and IgG, as well as and specific IgA and IgG antibody levels in the intestinal liquid by ELISA; ii) α­chain and polymeric immunoglobulin receptor (pIgR) protein expression in epithelial cell extracts analyzed by western blotting; iii) the mRNA expression levels of α­/J­chains, pIgR, IL­2, IL­4, IL­5 and IL­6 in whole mucosal samples by reverse transcription­quantitative PCR. Data were analyzed by one­way ANOVA, and the differences were analyzed by the Holm­Sidák post hoc test and were considered significant if P<0.05. Results from the present study revealed the upregulatory effects of chronic stress on the total antibody levels, protein (α­chain; 78­kDa pIgR) and mRNA (α­ and J­chains; pIgR; IL­6) expression levels were restricted by bLf under stress. The effects of chronic stress on the downregulation of IL­2 and IL­4 mRNA expression were not changed by bLf under stress. The corticosterone response in unstressed mice treated with 5,000 µg bLf and the specific­IgG levels in the unstressed and stressed groups treated with bLf at all doses were increased. The findings suggested an effect of bLf in maintaining homeostasis under stress.