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Biomedical subjects

Stephanie Blum

Publications and source records attributed to Stephanie Blum.

11 recordsLinked to original sources
PubMed2006

Anti-inflammatory effects of bifidobacteria by inhibition of LPS-induced NF-kappaB activation.

AIM: Different strains of bifidobacteria were analysed for their effects on HT-29 intestinal epithelial cells (IECs) in in vitro models both of the non-inflamed and inflamed intestinal epithelium. METHODS: A reporter gene system in HT-29 cells was used to measure levels of NF-kappaB activation after challenge with bifidobacteria or after bacterial pre-treatment following LPS challenge. IL-8 protein and pro-inflammatory gene expression was investigated using normal HT-29 cells. RESULTS: None of the bifidobacteria tested induced activation of nuclear factor kappaB (NF-kappaB) indicating that bifidobacteria themselves do not induce inflammatory events in IECs. However, six out of eight bifidobacteria tested inhibited lipopolysaccharide- (LPS-) induced NF-kappaB activation in a dose- and strain-dependent manner. In contrast, NF-kappaB activation in response to challenge with tumor necrosis factor-alpha (TNF-alpha) was affected by none of the tested bifidobacteria, indicating that the inhibitory effect of bifidobacteria is specific for LPS-induced inflammation in IECs. As shown with two of the six inhibition-positive bifidobacteria, LPS-induced inhibition of NF-kappaB activation was accompanied by a dose-dependent decrease of interleukin 8 (IL-8) secretion and by lower mRNA levels for IL-8, TNF-alpha, cyclooxygenase 2 (Cox-2), and intercellular adhesion molecule 1 (ICAM-1). CONCLUSION: Some strains of bifidobacteria are effective in inhibiting LPS-induced inflammation and thus might be appropriate candidates for probiotic intervention in chronic intestinal inflammation.

Bifidobacterium↗
PubMed2006

Interaction of bifidobacteria with Caco-2 cells-adhesion and impact on expression profiles.

The aim of the present study was to study different strains of bifidobacteria for adhesion to Caco-2 intestinal epithelial cells (IECs) and to test for the mRNA response of these cells following interaction with bifidobacteria. Adhesion was tested at different pH conditions using model epithelia consisting of transwell cultures of fully differentiated Caco-2 cells. Microarrays were used to characterize changes in global expression profiles of Caco-2 cells co-cultured with peripheral blood mononuclear cells (PBMCs) and challenged with non-pathogenic Escherichia coli D2241 or four different strains of bifidobacteria. Furthermore, cytokine mRNA of IECs in responses to challenge with Bifidobacterium bifidum S17 or E. coli D2241 was tested in PBMC-sensitised Caco-2 cells using RT-PCR. Bifidobacteria showed strain-specific adhesion to Caco-2. Shift of apical pH from 7 to 4.5 resulted in strain-specific changes of adhesion. Global expression profiles of PBMC-sensitised Caco-2 cells revealed differential expression of a significant number of genes only after challenge with E. coli D2241 while cells were essentially unresponsive to challenge with four strains of bifidobacteria showing different adhesion properties. Using a RT-PCR approach, in the same system a similar differential expression after challenge with E. coli D2241 or B. bifidum S17 was observed for various immune markers. The presented results suggest that Caco-2 cells might be specifically unresponsive to challenge with bifidobacteria irrespective of the level of adhesion.

Bacterial Adhesion↗
PubMed2006

Improvement of the human intestinal flora by ingestion of the probiotic strain Lactobacillus johnsonii La1.

To exert beneficial effects for the host, for example, improving the intestinal microflora, a probiotic must reach the intestine as a viable strain. These properties must be demonstrated by in vitro as well as in vivo methods. However, only a few well-designed human clinical studies have shown these properties. Lactobacillus johnsonii La1 has been shown to give many beneficial effects for the host, but it is unclear whether a viable strain of L. johnsonii La1 has the effect of improving host intestinal microflora. In the present study, a randomised double-blind placebo-controlled cross-over trial was conducted to elucidate the effect of L. johnsonii La1 on human intestinal microflora. Twenty-two young healthy Japanese women were randomly divided into two groups, and either received fermented milk with L. johnsonii La1 or a fermented milk without L. johnsonii La1 (placebo) daily for 21 d. Consumption of the fermented milk: (a) increased total Bifidobacterium and Lactobacillus, and decreased lecithinase-positive Clostridium in the faeces; (b) increased the faecal lactic acid concentrations; (c) decreased the faecal pH; (d) increased the defecation frequency. These changes were stronger than those observed with the placebo. L. johnsonii La1 was identified in all subjects only after the consumption of the fermented milk. These results suggest that L. johnsonii La1 can contribute to improve intestinal microflora with probiotic properties.

Adult↗
PubMed2005

Probiotics as a treatment strategy for gastrointestinal diseases?

Current interest in probiotics is motivated not only by the clinical data showing efficacy of some probiotic bacteria but also by the increasing antibiotic resistance of pathogenic bacteria (particularly in hospitals) and the rise of consumers' demand for natural substitutes of drugs. Only few randomized, double-blind placebo-controlled human trials are available, and some involved only small numbers of patients. They are difficult to compare because of differences in probiotic strains employed, doses and formulation. Among probiotic applications, reduction of diarrhea is probably the best-documented effect confirmed by recent meta-analyses. Literature on Helicobacter pylori indicates that probiotics are unable to eradicate the infection but could be useful in decreasing infection levels and as adjuvants of therapy-associated side effects. Studies performed in inflammatory bowel disease suggest that high doses of probiotics and most likely a combination of different lactobacilli and bifidobacteria are more effective in decreasing inflammatory score and maintaining patients in remission than a single probiotic strain. Probiotic studies evaluating amelioration of symptoms in irritable bowel syndrome would require more sustained patient numbers. However, accumulated data is encouraging and suggests that efficacy is strain-dependent. Finally, too few probiotic intervention trials have been reported on colon cancer to allow any firm conclusion.

Clinical Trials as Topic↗
PubMed2005

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.

Animals↗
PubMed2003

Divergent patterns of colonization and immune response elicited from two intestinal Lactobacillus strains that display similar properties in vitro.

Lactobacilli derived from the endogenous flora of normal donors are being increasingly used as probiotics in functional foods and as vaccine carriers. However, a variety of studies done with distinct strains of lactobacilli has suggested heterogeneous and strain-specific effects. To dissect this heterogeneity at the immunological level, we selected two strains of lactobacilli that displayed similar properties in vitro and studied their impact on mucosal and systemic B-cell responses in monoxenic mice. Germfree mice were colonized with Lactobacillus johnsonii (NCC 533) or Lactobacillus paracasei (NCC 2461). Bacterial loads were monitored for 30 days in intestinal tissues, and mucosal and systemic B-cell responses were measured. Although both Lactobacillus strains displayed similar growth, survival, and adherence properties in vitro, they colonized the intestinal lumen and translocated into mucosal lymphoid organs at different densities. L. johnsonii colonized the intestine very efficiently at high levels, whereas the number of L. paracasei decreased rapidly and it colonized at low levels. We determined whether this difference in colonization correlated with an induction of different types of immune responses. We observed that colonization with either strain induced similar germinal center formation and immunoglobulin A-bearing lymphocytes in the mucosa, suggesting that both strains were able to activate mucosal B-cell responses. However, clear differences in patterns of immunoglobulins were observed between the two strains in the mucosa and in the periphery. Therefore, despite similar in vitro probiotic properties, distinct Lactobacillus strains may colonize the gut differently and generate divergent immune responses.

Animals↗
PubMed2003

Intestinal microflora and homeostasis of the mucosal immune response: implications for probiotic bacteria?

The intestinal microflora can be considered a postnatally acquired organ that is composed of a large diversity of bacteria that perform important functions for the host and can be modulated by environmental factors, such as nutrition. Specific components of the intestinal microflora, including lactobacilli and bifidobacteria, have been associated with beneficial effects on the host, such as promotion of gut maturation and integrity, antagonisms against pathogens and immune modulation. Beyond this, the microflora seems to play a significant role in the maintenance of intestinal immune homeostasis and prevention of inflammation. The contribution of the intestinal epithelial cell in the first line of defense against pathogenic bacteria and microbial antigens has been recognized. However, the interactions of intestinal epithelial cells with indigenous bacteria are less well understood. This review will summarize the increasing scientific attention to mechanisms of the innate immune response of the host towards different components of the microflora, and suggest a potential role for selected probiotic bacteria in the regulation of intestinal inflammation.

Animals↗
PubMed2002

IL-10 producing CD14low monocytes inhibit lymphocyte-dependent activation of intestinal epithelial cells by commensal bacteria.

Intestinal epithelial cell (IEC) activation by non-pathogenic, commensal bacteria was demonstrated to require the presence of immunocompetent cells. In this study, HT-29 and CaCO-2 transwell cultures, reconstituted with CD4+ and CD8+ T cells, CD19+ B cells and CD14high monocytes, were challenged with non-pathogenic Gram negative Escherichia coli and Gram positive lactobacilli. Cytokine expression was analysed by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assays (ELISA). Expression of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-8 mRNA in E. coli or L. sakei challenged IEC was promoted by lymphocyte populations predominantly CD4+ T cells, while monocytes failed to mediate an inflammatory cytokine response. The monocyte phenotype and function were further characterised by flow cytometry and mixed lymphocyte reaction (MLR). During the co-culture with IEC and bacterial stimulated IEC, CD14high peripheral blood monocytes acquired a CD14low CD16low phenotype with reduced expression co-stimulatory (CD80, CD86, CD58) cell surface molecules. Immunosuppressive functions of IEC conditioned CD14low monocytes were demonstrated by the predominant secretion of IL-10 and IL-IRa and their reduced potential to trigger an allogeneic lymphocyte response. In conclusion, IEC contribute to the development of CD14low CD16low monocytes with immunosuppressive function and antagonised a lymphocyte-mediated activation of the intestinal epithelium in response to intestinal and food derived bacteria. These results strengthen the hypothesis that the gut epithelium constitutes an important functional element in the regulation of mucosal immune homeostasis towards commensal bacteria.

Biomarkers↗
PubMedDate not supplied

Milk casein-based diet containing TGF-beta controls the inflammatory reaction in the HLA-B27 transgenic rat model.

BACKGROUND: A casein-based formula containing TGF-beta has been successfully used in adolescents during acute episodes of Crohn's disease. The role played by this molecule requires confirmation. We have examined the capacity of a TGF-beta containing diet to control the intestinal inflammation in HLA-B27 transgenic rats, and compared its effects with a similar diet devoid of TGF-beta. METHODS: Three groups of rats were studied. HLA-B27/hbeta2M transgenic rats were fed with a casein-based rat-adapted diet containing TGF-beta or a control casein-based diet without TGF-beta. Fischer control animals were fed the latter. Body weight, dietary intake, tissue weights, fecal samples, leukocyte counts, and acute phase response were analyzed. Intestinal inflammation was assessed by histology, myeloperoxidase, and mRNA expression of cytokines. MUC2 protein expression was assessed by immunohistochemistry. Breakdown of muscle protein was examined. RESULTS: The test diet improved diarrhea increasing the fecal dry matter and the colonic inflammation as shown by a lower inflammatory score (2.43 +/- 1.13 vs 4.42 +/- 0.53, p < .05), lower mucosal thickness (431.25 +/- 72.29 vs 508.57 +/- 81.32 microm, p = .08) and decreased IFNgamma mRNA expression. MUC2 protein expression was increased in HLA rats fed the TGF-beta diet compared with HLA rats fed the control diet, but restitution to normal pattern was not observed. The test diet also decreased leukocytosis and the acute phase response and improved the muscle catabolic response. CONCLUSION: The TGF-beta containing diet has a beneficial effect in an animal model of intestinal inflammation. Our observations support a potential role for dietary TGF-beta in the restoration of immune homeostasis.

Acute-Phase Reaction↗
PubMedDate not supplied

Supplementation with oral probiotic bacteria maintains cutaneous immune homeostasis after UV exposure.

Probiotic bacteria have been shown to modulate the immune system of the gut and protect against infectious and inflammatory diseases of the gastro-intestinal tract. Ultraviolet radiation (UVR) is known to alter the cutaneous and systemic immune systems implicated in the development of skin tumors. In this study we investigated whether oral probiotics are able to modulate the immune system of the skin using hairless Skh:hr1 mice exposed to an acute dose of UVR. We show that nutritional supplementation with Lactobacillus johnsonii (La1) at 10(8) cfu/day for 10 days was able to protect against the UVR-induced suppression of contact hypersensitivity, the decreased epidermal Langerhans cell density and the increased IL-10 serum levels. In the absence of UV exposure, probiotic bacteria had no detectable effect on the immune system of the skin, thus acting only to re-establish skin homeostasis. In conclusion, our data demonstrate that ingested probiotic bacteria can maintain cutaneous immune capacity after UV exposure.

Animals↗