Probiotics mucosal cells

To maximize the colonization potential of a probiotic strain, the ability to adhere to human mucosal cells maybe an advantage. The ability of certain probiotic strains to hinder adhesion of pathogens, or their toxins, to human cells has been proposed as one possible mode of probiotic action. However, despite positive results in anti-pathogen adhesion assays in vitro, such activity has not been demonstrated in the human gastrointestinal tract. Indeed, we know little about which species of commensal bacteria adhere to the gut wall and the health outcomes of such interactions. 

A Lactobacillus strain was recently shown to inhibit competitively adhesion of enteropathogenic E. coli to pig ileum and interfered with bacterial attachment to the mucosal layer of ileal conducts (Blomberg et al., 1993). Although L. acidophilus inhibits the adhesion of several enteric pathogens to human intestinal cells in culture, when pathogen attachment preceded L. acidophilus treatment, no inhibitory interference occurred indicating that steric hindrance of site occupation is important in the inhibition of adhesion. Thus, therapeutic use is likely to be limited to preventive application of probiotics. 

Probiotic bacteria regulate mucosal immune responses through induction of anti-inflammatory cytokines such as IL-10 and TGF-p, while decreasing expression of proinflammatory cytokines, such as TNF and IFN-y (Corr et al., 2007a Di Giacinto et al., 2005 Silva et al., 2004). B. breve and Streptococcus thermophilus secrete metabolites which inhibit LPS-induced TNF-a secretion from peripheral blood mononuclear cell (PBMC) monolayers (Menard et al., 2004). We demonstrated a significant reduction in interleukin-8 (IL-8) and an increase in IL-10 cytokines secreted from epithelial cells following pretreatment with probiotics... 

Pronio, A., Montesani, C., Butteroni, C., Vecchione, S., Mumolo, G., Vestri, A., Vitolo, D., and Boirivant, M. (2008). Probiotic administration in patients with ileal pouch-anal anastomosis for ulcerative colitis is associated with expansion of mucosal regulatory cells. Inflamm. Bowel Dis. 14(5), 662-668. 

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... 

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