Effect of perorally administered lactobacilli on macrophage activation in mice

Abstract

The effect of perorally (p.o.) administered Lactobacillus casei and L. bulgaricus on macrophage activation in mice was studied. L. casei and L. bulgaricus were administered p.o. to mice for 8 days. The macrophage activation was measured on days 2, 3, 5, and 8 of lactobacillus administration by using biochemical and functional criteria. We measured the release of lysosomal hydrolases, the level of a nonlysosomal enzyme, and in vitro phagocytic activity of mouse peritoneal macrophages. All the assays were performed comparatively with mice inoculated with L. casei and L. bulgaricus (viable and nonviable cells) intraperitoneally (i.p.) at the same dose as for p.o. administration. The phagocytic activity was significantly higher in mice treated i.p. than in control mice. For p.o. administration, there was an increase only when L. casei was used. L. bulgaricus had little effect. No differences were found between viable and nonviable cells. The phagocytic function of the reticuloendothelial system was tested by the carbon clearance test, which showed that L. casei and L. bulgaricus accelerate the phagocytic function in mice treated p.o and i.p., from day 2 onward. These observations show that L. casei and L. bulgaricus given by p.o. administration are able to activate macrophages in mice and suggest that these bacteria, when passing through the intestinal tract, may be responsible for the enhanced host immune response. This fact is very significant because the diet includes fermented and manufactured products containing lactobacilli.

Expression of mRNA encoding IFNα in macrophages stimulated with Lactobacillus gasseri

“…In this study, we demonstrated that murine M~b produce IFN when exposed to some strains of heat-killed L. gasseri. Both live and killed lactic acid bacteria exhibit biological activity [16][17][18][19]. We found that live L. gasseri DSM20243 T also induced IFN production (data not shown).…”

Enhanced clearance of Candida albicans from the oral cavities of mice following oral administration of Lactobacillus acidophilus

“…Probiotic bacteria have been used extensively within the food industry, largely in fermented milk products. Claims of probiotic promotion of host defence have been supported by reports of enhanced phagocytosis [12,13], stimulation of production of various cytokines (including IL-2, IL-4, IL-10, IL-12, IL-18 and INF-g ) [14][15][16][17][18][19] and increased mucosal and secretory antibody levels in response to gut infection with rotavirus [20][21][22] or Salmonella typhi Ty21a [20,23], supporting the notion that some probiotics can enhance mucosal immunity. Feeding adult or neonatal nude mice probiotics prolonged their survival following intestinal challenge with live C. albicans by enhancing both antibody and cell-mediated immunity [24,25].…”

Protective effect of intranasally inoculated Lactobacillus fermentum against Streptococcus pneumoniae challenge on the mouse respiratory tract

“…This was reinforced by experiments eval- uated at the ultra structural level, using electron microscopy [22]. The mechanisms suggested in the protective e¡ect of probiotic microorganisms [16] are very broad: from competitive exclusion [17], nutrient competition [31], production of antagonistic substances (lactic acid, hydrogen peroxide [32], bacteriocins [33]) up to immune system stimulation [14,15]. From the results obtained in the present paper, it can be suggested that the intervention of the immune system could be involved as one of the main mechanisms responsible for the protective e¡ect exerted on S. pneumoniae infection and is based on the following grounds:…”