An Overview of the Influence of Breastfeeding on the Development of Inflammatory Bowel Disease

The first 1000 days of life is a critical period that contributes significantly to the programming of an individual's future health. Among the many changes that occur during this period early in life, there is growing evidence that the establishment of healthy gut microbiota plays an important role in the prevention of both short- and long-term health problems. Numerous publications suggest that the quality of the gut microbiota colonisation depends on several dietary factors, including breastfeeding. In this respect, a relationship between breastfeeding and the risk of inflammatory bowel disease (IBD) has been suggested. IBDs are chronic intestinal diseases, and perinatal factors may be partly responsible for their onset. We review the existence of links between breastfeeding and IBD based on experimental and clinical studies. Overall, despite encouraging experimental data in rodents, the association between breastfeeding and the development of IBD remains controversial in humans, partly due to the considerable heterogeneity between clinical studies. The duration of exclusive breastfeeding is probably decisive for its lasting effect on IBD. Thus, specific improvements in our knowledge could support dietary interventions targeting the gut microbiome, such as the early use of prebiotics, probiotics or postbiotics, in order to prevent the disease.

Lactobacillus fermentum ACA-DC 179 displays probiotic potential in vitro and protects against trinitrobenzene sulfonic acid (TNBS)-induced colitis and Salmonella infection in murine models

Lactobacillus fermentum ACA-DC 179, Lactobacillus plantarum ACA-DC 287 and Streptococcus macedonicus ACA-DC 198 were studied for their probiotic potential. Firstly, strains were screened for antimicrobial activity towards a broad range of target strains, including lactic acid bacteria, food spoilage and pathogenic bacteria. L. fermentum ACA-DC 179 was active against five streptococci, including the two pathogenic strains Streptococcus oralis LMG 14532T and Streptococcus pneumoniae LMG 14545T. S. macedonicus ACA-DC 198 was active against the majority of the strains tested, including not only lactic acid bacteria but also many food spoilage or pathogenic species. The three potential probiotic strains were found to survive variably at pH 2.5 and were unaffected by bile salts. Only S. macedonicus ACA-DC 198 exhibited bile salt hydrolase activity, while none of the strains was haemolytic. Moreover, strains exhibited variable susceptibility towards commonly used antibiotics. L. plantarum ACA-DC 287 and S. macedonicus ACA-DC 198 induced the secretion of the pro-inflammatory cytokines IL-12, IFN-gamma and TNF-alpha by human peripheral blood mononuclear cells. Also elevated levels of the anti-inflammatory IL-10 were observed with L. fermentum ACA-DC 179. This strain consequently was found to significantly reduce colitis in a TNBS-induced colitis mouse model. Furthermore, L. fermentum ACA-DC 179 was successfully applied in an experimental Salmonella-infection mouse model. To conclude, strain L. fermentum ACA-DC 179 possesses desirable probiotic properties, such as antimicrobial activity and immunomodulation in vitro, which were confirmed in vivo by the use of animal models.

Prevention and treatment of colitis with Lactococcus lactis secreting the immunomodulatory Yersinia LcrV protein

BACKGROUND & AIMS

The low calcium response V (LcrV) protein synthesized by gram-negative, pathogenic yersiniae participates in bacterial evasion of the host's innate immune response by stimulating synthesis of the anti-inflammatory interleukin (IL)-10 and preventing the activation of proinflammatory cytokines.

METHODS

We genetically engineered the food-grade bacterium Lactococcus lactis to secrete the LcrV protein from the enteropathogenic species Yersinia pseudotuberculosis. The protective and therapeutic potential of orally administered LcrV-secreting L lactis was evaluated in 2 models of acute experimental colitis (induced by trinitrobenzene sulfonic acid [TNBS] and dextran sodium sulfate [DSS], respectively) in wild-type and knockout mice.

RESULTS

Oral administration of LcrV-secreting L lactis led to active delivery of LcrV and induction of IL-10 (via a Toll-like receptor 2-dependent pathway) in the colon and prevented TNBS-induced colitis, in contrast to the L lactis control not producing LcrV. Down-regulation of tissue inflammatory markers correlated well with the reduction in damage to the colonic mucosa. In contrast, TNBS-induced colitis was not prevented in IL-10(-/-) mice pretreated with LcrV-secreting L lactis, thus showing that IL-10 is required for LcrV protection. Administration of LcrV-secreting L lactis also proved to be very effective in preventing and treating acute DSS-induced colitis.

CONCLUSIONS

LcrV-secreting L lactis decreased experimentally induced intestinal inflammation in 2 murine models of colitis. This novel approach highlights the potential of using pathogen-derived immunomodulating molecules in vivo as novel therapeutics for inflammatory bowel diseases.

CARD15/NOD2 is required for Peyer's patches homeostasis in mice

Background

CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches (PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis.

Methodology/Principal Findings

At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4⁺ T-cells. KO mice were also characterised by higher concentrations of TNFα, IFNγ, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By Ussing chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS.

Conclusions

Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD.

A key role of dendritic cells in probiotic functionality

BACKGROUND

Disruption of the intestinal homeostasis and tolerance towards the resident microbiota is a major mechanism involved in the development of inflammatory bowel disease. While some bacteria are inducers of disease, others, known as probiotics, are able to reduce inflammation. Because dendritic cells (DCs) play a central role in regulating immune responses and in inducing tolerance, we investigated their role in the anti-inflammatory potential of probiotic lactic acid bacteria.

METHODOLOGY/PRINCIPAL FINDINGS

Selected LAB strains, while efficiently taken up by DCs in vitro, induced a partial maturation of the cells. Transfer of probiotic-treated DCs conferred protection against 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Protection was associated with a reduction of inflammatory scores and colonic expression of pro-inflammatory genes, while a high local expression of the immunoregulatory enzyme indolamine 2, 3 dioxgenase (IDO) was observed. The preventive effect of probiotic-pulsed DCs required not only MyD88-, TLR2- and NOD2-dependent signaling but also the induction of CD4+ CD25+ regulatory cells in an IL-10-independent pathway.

CONCLUSIONS/SIGNIFICANCE

Altogether, these results suggest that selected probiotics can stimulate DC regulatory functions by targeting specific pattern-recognition receptors and pathways. The results not only emphasize the role of DCs in probiotic immune interactions, but indicate a possible role in immune-intervention therapy for IBD.

Correlation between in vitro and in vivo immunomodulatory properties of lactic acid bacteria

AIM: To investigate the correlation between the in vitro immune profile of probiotic strains and their ability to prevent experimental colitis in mice.

METHODS: in vitro immunomodulation was assessed by measuring interleukin (IL)-12p70, IL-10, tumor necrosis factor alpha (TNFα) and interferon γ (IFNγ) release by human peripheral blood mononuclear cells (PBMCs) after 24 h stimulation with 13 live bacterial strains. A murine model of acute TNBS-colitis was next used to evaluate the prophylactic protective capacity of the same set of strains.

RESULTS: A strain-specific in vivo protection was observed. The strains displaying an in vitro capacity to induce higher levels of the anti-inflammatory cytokine IL-10 and lower levels of the inflammatory cytokine IL-12, offered the best protection in the in vivo colitis model. In contrast, strains leading to a low IL-10/IL-12 cytokine ratio could not significantly attenuate colitis symptoms.

CONCLUSION: These results show that we could predict the in vivo protective capacity of the studied lactic acid bacteria (LAB) based on the cytokine profile we established in vitro. The PBMC-based assay we used may thus serve as a useful primary indicator to narrow down the number of candidate strains to be tested in murine models for their anti-inflammatory potential.

Trophic status of the small intestine in young and aged rats: modulation by a yogurt-supplemented diet

Among the multifactorial causes of undernutrition in old age, gastrointestinal mucosa altered function and resulting specific malabsorption are the most relevant. Despite numerous studies that have dealt with the effects of aging on the digestive tract of mammals, results showed discrepancies in terms of proliferation and biochemical aging small intestine events. However, the slowing-down of the maturation process and the poor adaptation of metabolism and intestinal function are obvious and there is evidence that protective mechanisms are impaired with age and contribute to affecting the trophic activity and related systemic homeostasis. Good prospects to improve gastrointestinal function in the elderly are essential and research on nutritional intervention to limit and counteract age-related impairments must be extensive. Probiotics are good candidates and fermented milks might be of great interest. In the present study we first show the main structural and functional variations between 3- and 23-month-old rat small intestines. The trophic consequences of aging and nutritional adaptation under basal conditions are also analyzed and discussed after 20 days of a yogurt-supplemented specific diet in both young and aged rats. The main variations that occur with aging and yogurt diet are located in the proximal small intestine. The present findings indicate a slight improvement of morphological trophic parameters in both young and aged rats by yogurt, whereas enzymatic changes are more discrete. Despite the obvious age-related decrease in trophicity, we suggest that assessment of probiotic potentials on trophicity requires a more altered model than normal, healthy aging animals.

Yersinia pseudotuberculosis anti-inflammatory components reduce trinitrobenzene sulfonic acid-induced colitis in the mouse

Rectal instillation of trinitrobenzene sulfonic acid (TNBS) induces acute colitis in the mouse. We tested the efficacy of Yersinia pseudotuberculosis anti-inflammatory components in preventing TNBS-triggered colitis. Animals were orally inoculated with virulence-attenuated Yersinia cells (a phoP mutant) prior to TNBS administration. Under these experimental conditions, colonic lesions and tumor necrosis factor alpha mRNA levels were significantly reduced.

Consequences of adrenalectomy on small intestine trophic parameters in aged and young rats: evidence of defective adaptation by aging and lack of corticoids

Previous study pointed to an important role of adrenals and glucocorticoids in the trophic status of the adult small intestine mucosa, with possible implications during stress events. Small intestine morphological and biochemical consequences of 10-day bilateral adrenalectomy and also sham-related laparotomy were determined in 23-month-old Sprague-Dawley rats. As described in young rats, adrenalectomy in old rats leads to partial atrophy and disorganization of the proximal small intestine epithelium, with an increase in the number of Paneth cells and reduced crypt cell proliferation. We also observed a decrease of goblet cell number and a reduction of all enzyme activities including disaccharidases, in contrast with the specific induced response shown in young rats. A number of marked biochemical effects have also been noted in aged rats subjected to solely laparotomy, suggesting age-related adaptation impairments. In conclusion, adrenalectomy modified the differentiation processes of the small intestinal mucosa in both young and aged rats, and some parameters underlined that the lack of corticoid-mediated adaptive process are exacerbated by cumulative surgical stress (event) and aging.

Changes in cell proliferation and differentiation of adult rat small intestine epithelium after adrenalectomy: kinetic, biochemical, and morphological studies

The effects of 10-day bilateral adrenalectomy on morphometry, proliferation, and apoptosis were determined in the small intestine of 3-month-old Sprague-Dawley rats. The activities of sucrase, lactase, and its respective mRNA, aminopeptidase N, and intestinal alkaline phosphatase were also evaluated. Adrenalectomy lead to partial atrophy and disorganization of the epithelium, with an increased number of goblet and Paneth cells and a reduction of crypt cell proliferation paralleled by a marked increase in villus apoptosis. Biochemical assays revealed that aminopeptidase N and intestinal alkaline phosphatase activities were significantly decreased, whereas disaccharidases were increased by adrenalectomy. The corresponding induction of lactase mRNA suggests an active response of the epithelium. In conclusion, adrenalectomy modified maturation and the differentiation processes of the small intestinal mucosa, especially in the proximal part of the small intestine. This result points to an important role of adrenals and glucocorticoids in the trophic status of the adult small intestinal mucosa.