Probiotic Administration in Stress Process

Stress can be defined as the physiological reaction of an organism to external or internal stimuli in which the body initiates various defense mechanisms to maintain homeostasis (Ramsey 1982 Cruz et al. 2012). The stress response involves a complex network of mechanisms essential for survival, mediated by neurotransmitters, peptidic hormones, and endocrine hormones from the enteric nervous system (ENS). These molecules modulate the humoral and cellular components of the intestinal immune system (de Jonge 2013). 

Stress influences gut mucosal immune response producing a diminution in the number of IgA+ B-lymphocytes in the lamina propria of the small intestine and in the secretion of S-IgA into the intestinal fluid of stressed animals. The probiotic strain Lact. casei CRL 431 increased these parameters in agreement with another study in a mouse stress model (Jarillo-Luna et al. 2007). The decrease in IgA+ cell numbers in stressed mice could be due to high levels of glucocorticoids that induce apoptosis of B cells in the lamina propria of the gut (Fukuzuka et al. 2000 Brunner et al. 2001 Ruiz-Santana et al. 2001). Another possibility could be the low number of CD4+ T cells. These last cells produce cytokines such as IFNy, IL-6, IL-5, IL-4, and IL-10, which are involved in the expansion and differentiation of IgA+ B cells (Iwakabe et al. 1998 Elenkov 2004 Brandtzaeg and Johansen 2005). These cell populations increased in stressed animals consuming probiotics. 

Macrophages and DC are very important in innate and adaptive immunity, and CD lib and CD 11 c are used respectively as markers to identify them. In the gut, these cells are involved in the bacterial clearance to avoid invasion of translocating bacteria from the intestinal lumen to deep tissues and to maintain intestinal homeostasis. In previous work, we demonstrated that the main mechanism by which the probiotic strain Lact. casei CRL 431 influences the gut mucosal immunity is through activation of the innate immune response (Maldonado Galdeano and Perdigdn 2006). For this reason we analyzed whether the stress induced changes in the expression of both markers in the immune cells present in the lamina propria of the small intestine of mice. The number of CDllb+ cells 

The number of IgA+, CDllb+, CDllc+, CD4+ and CD8+ T cells were determined by direct immunofluorescence on the small intestine tissue slides of mice from different experimental groups normal control (NC), normal control with Lact. casei CRL 431 (NC+P), stressed control (SC) and stressed control with Lact. casei CRL 431. 

Results are expressed as the number of positive cells per 10 fields of vision (lOOOX). Values are means for n = 9 mice SD. Secretory IgA was measured by ELISA in the intestinal fluid of the small intestine of mice from different experimental groups. Data correspond to the mean SD of results of n = 9 animals from three separate experiments s.b.c,(i Means for each cell population without a common letter differ significantly (P 0.05). Values are those obtained from Palomar et al. (2014). 

---