Lactobacillus paracasei Reduces Intestinal Inflammation in Adoptive Transfer Mouse Model of Experimental Colitis

Studies showed that specific probiotics provide therapeutic benefits in inflammatory bowel disease. In vitro evidence suggested that Lactobacillus paracasei also called ST11 (CNCM I-2116) is a potent strain with immune modulation properties. However, little is known about its capacity to alleviate inflammatory symptoms in vivo In this context, the main objective of this study was to investigate the role of ST11 on intestinal inflammation using the adoptive transfer mouse model of experimental colitis. Rag2−/− recipient mice were fed with ST11 (109 CFU/day)a month prior toinduce colitis by adoptive transfer of naive T cells. One month later, in clear contrast to nonfed mice, weight loss was significantly reduced by 50% in ST11-fed mice. Further analysis of colon specimens revealed a significant reduction neutrophil infiltration and mucosal expression of IL1β, IL-6, and IL12 proinflammatory cytokines, whereas no consistent differences in expression of antibacterial peptides or tight junction proteins were observed between PBS and ST11-fed mice. All together, our results demonstrate that oral administration of ST11 was safe and had a significant preventive effect on colitis. We conclude that probiotics such as Lactobacillus paracasei harbor worthwhile in vivo immunomodulatory properties to prevent intestinal inflammation by nutritional approaches

Potential role of the intestinal microbiota of the mother in neonatal immune education

Mucosal dendritic cells are at the heart of decision-making processes that dictate immune reactivity to intestinal microbes. They ensure tolerance to commensal bacteria and a vigorous immune response to pathogens. It has recently been demonstrated that the former involves a limited migration of bacterially loaded dendritic cells from the Peyer's patches to the mesenteric lymph nodes. During lactation, cells from gut-associated lymphoid tissue travel to the breast via the lymphatics and peripheral blood. Here, we show that human peripheral blood mononuclear cells and breast milk cells contain bacteria and their genetic material during lactation. Furthermore, we show an increased bacterial translocation from the mouse gut during pregnancy and lactation and the presence of bacterially loaded dendritic cells in lactating breast tissue. Our observations show bacterial translocation as a unique physiological event, which is increased during pregnancy and lactation. They suggest endogenous transport of intestinally derived bacterial components within dendritic cells destined for the lactating mammary gland. They also suggest neonatal immune imprinting by milk cells containing commensal-associated molecular pattern

Potential role of the intestinal microbiota of the mother in neonatal immune education

Mucosal dendritic cells are at the heart of decision-making processes that dictate immune reactivity to intestinal microbes. They ensure tolerance to commensal bacteria and a vigorous immune response to pathogens. It has recently been demonstrated that the former involves a limited migration of bacterially loaded dendritic cells from the Peyer's patches to the mesenteric lymph nodes. During lactation, cells from gut-associated lymphoid tissue travel to the breast via the lymphatics and peripheral blood. Here, we show that human peripheral blood mononuclear cells and breast milk cells contain bacteria and their genetic material during lactation. Furthermore, we show an increased bacterial translocation from the mouse gut during pregnancy and lactation and the presence of bacterially loaded dendritic cells in lactating breast tissue. Our observations show bacterial translocation as a unique physiological event, which is increased during pregnancy and lactation. They suggest endogenous transport of intestinally derived bacterial components within dendritic cells destined for the lactating mammary gland. They also suggest neonatal immune imprinting by milk cells containing commensal-associated molecular patterns.Facultad de Ciencias Exacta

Potential role of the intestinal microbiota of the mother in neonatal immune education

Mucosal dendritic cells are at the heart of decision-making processes that dictate immune reactivity to intestinal microbes. They ensure tolerance to commensal bacteria and a vigorous immune response to pathogens. It has recently been demonstrated that the former involves a limited migration of bacterially loaded dendritic cells from the Peyer's patches to the mesenteric lymph nodes. During lactation, cells from gut-associated lymphoid tissue travel to the breast via the lymphatics and peripheral blood. Here, we show that human peripheral blood mononuclear cells and breast milk cells contain bacteria and their genetic material during lactation. Furthermore, we show an increased bacterial translocation from the mouse gut during pregnancy and lactation and the presence of bacterially loaded dendritic cells in lactating breast tissue. Our observations show bacterial translocation as a unique physiological event, which is increased during pregnancy and lactation. They suggest endogenous transport of intestinally derived bacterial components within dendritic cells destined for the lactating mammary gland. They also suggest neonatal immune imprinting by milk cells containing commensal-associated molecular patterns.Facultad de Ciencias Exacta

Effects of increase in fish oil intake on intestinal eicosanoids and inflammation in a mouse model of colitis

BACKGROUND: Inflammatory bowel diseases (IBD) are chronic intestinal inflammatory diseases affecting about 1% of western populations. New eating behaviors might contribute to the global emergence of IBD. Although the immunoregulatory effects of omega-3 fatty acids have been well characterized in vitro, their role in IBD is controversial. METHODS: The aim of this study was to assess the impact of increased fish oil intake on colonic gene expression, eicosanoid metabolism and development of colitis in a mouse model of IBD. Rag-2 deficient mice were fed fish oil (FO) enriched in omega-3 fatty acids i.e. EPA and DHA or control diet for 4 weeks before colitis induction by adoptive transfer of naïve T cells and maintained in the same diet for 4 additional weeks. Onset of colitis was monitored by colonoscopy and further confirmed by immunological examinations. Whole genome expression profiling was made and eicosanoids were measured by HPLC-MS/MS in colonic samples. RESULTS: A significant reduction of colonic proinflammatory eicosanoids in FO fed mice compared to control was observed. However, neither alteration of colonic gene expression signature nor reduction in IBD scores was observed under FO diet. CONCLUSION: Thus, increased intake of dietary FO did not prevent experimental colitis

Lactobacillus johnsonii La1 antagonizes Giardia intestinalis in vivo

This study describes the in vivo activity of Lactobacillus johnsonii La1 (NCC533) in Giardia intestinalis-infected gerbils (Meriones unguiculatus). Daily administration of lactobacilli in the drinking water from 7 days before inoculation with Giardia trophozoites efficiently prevented G. intestinalis strain WB clone C6 from infecting gerbils. More specifically, shedding of fecal Giardia antigens (GSA65 protein) was diminished in the La1-treated group, and resolution of infection was observed by 21 days postinoculation. Histology and analysis of enzymatic markers of microvillus membrane integrity revealed that probiotic administration also protected against parasite-induced mucosal damage. In addition, a cellular response to Giardia antigens was stimulated in spleen cells from La1-treated gerbils. Results show for the first time the antigiardial effect of probiotic lactobacilli in vivo and provide further insight into the antagonistic properties of lactic acid bacteria against protozoa involved in intestinal infections.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Potential role of the intestinal microbiota of the mother in neonatal immune education

Mucosal dendritic cells are at the heart of decision-making processes that dictate immune reactivity to intestinal microbes. They ensure tolerance to commensal bacteria and a vigorous immune response to pathogens. It has recently been demonstrated that the former involves a limited migration of bacterially loaded dendritic cells from the Peyer's patches to the mesenteric lymph nodes. During lactation, cells from gut-associated lymphoid tissue travel to the breast via the lymphatics and peripheral blood. Here, we show that human peripheral blood mononuclear cells and breast milk cells contain bacteria and their genetic material during lactation. Furthermore, we show an increased bacterial translocation from the mouse gut during pregnancy and lactation and the presence of bacterially loaded dendritic cells in lactating breast tissue. Our observations show bacterial translocation as a unique physiological event, which is increased during pregnancy and lactation. They suggest endogenous transport of intestinally derived bacterial components within dendritic cells destined for the lactating mammary gland. They also suggest neonatal immune imprinting by milk cells containing commensal-associated molecular patterns.Facultad de Ciencias Exacta

Lactobacillus johnsonii La1 antagonizes Giardia intestinalis in vivo

This study describes the in vivo activity of Lactobacillus johnsonii La1 (NCC533) in Giardia intestinalis-infected gerbils (Meriones unguiculatus). Daily administration of lactobacilli in the drinking water from 7 days before inoculation with Giardia trophozoites efficiently prevented G. intestinalis strain WB clone C6 from infecting gerbils. More specifically, shedding of fecal Giardia antigens (GSA65 protein) was diminished in the La1-treated group, and resolution of infection was observed by 21 days postinoculation. Histology and analysis of enzymatic markers of microvillus membrane integrity revealed that probiotic administration also protected against parasite-induced mucosal damage. In addition, a cellular response to Giardia antigens was stimulated in spleen cells from La1-treated gerbils. Results show for the first time the antigiardial effect of probiotic lactobacilli in vivo and provide further insight into the antagonistic properties of lactic acid bacteria against protozoa involved in intestinal infections.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Role of secretory IgA in the mucosal sensing of commensal bacteria

While the gut epithelium represents the largest mucosal tissue, the mechanisms underlying the interaction between intestinal bacteria and the host epithelium lead to multiple outcomes that remain poorly understood at the molecular level. Deciphering such events may provide valuable information as to the mode of action of commensal and probiotic microorganisms in the gastrointestinal environment. Potential roles of such microorganisms along the privileged target represented by the intestinal immune system include maturation processes prior, during and after weaning, and the reduction of inflammatory reactions in pathogenic conditions. As commensal bacteria are naturally coated by natural and antigen-specific SIgA in the gut lumen, understanding the consequences of such an interaction may provide new clues on how the antibody contributes to homeostasis at mucosal surfaces. This review discusses several aspects of the role of SIgA in the essential communication existing between the host epithelium and members of its microbiota

Potentiation of Polarized Intestinal Caco-2 Cell Responsiveness to Probiotics Complexed with Secretory IgA*

The precise mechanisms underlying the interaction between intestinal bacteria and the host epithelium lead to multiple consequences that remain poorly understood at the molecular level. Deciphering such events can provide valuable information as to the mode of action of commensal and probiotic microorganisms in the gastrointestinal environment. Potential roles of such microorganisms along the privileged target represented by the mucosal immune system include maturation prior, during and after weaning, and the reduction of inflammatory reactions in pathogenic conditions. Using human intestinal epithelial Caco-2 cell grown as polarized monolayers, we found that association of a Lactobacillus or a Bifidobacterium with nonspecific secretory IgA (SIgA) enhanced probiotic adhesion by a factor of 3.4-fold or more. Bacteria alone or in complex with SIgA reinforced transepithelial electrical resistance, a phenomenon coupled with increased phosphorylation of tight junction proteins zonula occludens-1 and occludin. In contrast, association with SIgA resulted in both enhanced level of nuclear translocation of NF-κB and production of epithelial polymeric Ig receptor as compared with bacteria alone. Moreover, thymic stromal lymphopoietin production was increased upon exposure to bacteria and further enhanced with SIgA-based complexes, whereas the level of pro-inflammatory epithelial cell mediators remained unaffected. Interestingly, SIgA-mediated potentiation of the Caco-2 cell responsiveness to the two probiotics tested involved Fab-independent interaction with the bacteria. These findings add to the multiple functions of SIgA and underscore a novel role of the antibody in interaction with intestinal bacteria