Probiotics and immune health

Metabolic diseases and pro- and prebiotics: Mechanistic insights

Metabolic diseases, such as obesity and type 2 diabetes, are world-wide health problems. The prevalence of metabolic diseases is associated with dynamic changes in dietary macronutrient intake during the past decades. Based on national statistics and from a public health viewpoint, traditional approaches, such as diet and physical activity, have been unsuccessful in decreasing the prevalence of metabolic diseases. Since the approaches strongly rely on individual’s behavior and motivation, novel science-based strategies should be considered for prevention and therapy for the diseases. Metabolism and immune system are linked. Both overnutrition and infection result in inflammation through nutrient and pathogen sensing systems which recognize compounds with structural similarities. Dietary macronutrients (fats and sugars) can induce inflammation through activation of an innate immune receptor, Toll-like receptor 4 (TLR4). Long-term intake of diets high in fats and meats appear to induce chronic systemic low-grade inflammation, endotoxicity, and metabolic diseases. Recent investigations support the idea of the involvement of intestinal bacteria in host metabolism and preventative and therapeutic potentials of probiotic and prebiotic interventions for metabolic diseases. Specific intestinal bacteria seem to serve as lipopolysaccharide (LPS) sources through LPS and/or bacterial translocation into the circulation due to a vulnerable microbial barrier and increased intestinal permeability and to play a role in systemic inflammation and progression of metabolic diseases. This review focuses on mechanistic links between metabolic diseases (mainly obesity and type 2 diabetes), chronic systemic low-grade inflammation, intestinal environment, and nutrition and prospective views of probiotic and prebiotic interventions for the diseases.

Suitability of a probiotic Lactobacillus paracasei strain as a starter culture in olive fermentation and development of the innovative patented product "probiotic table olives"

Probiotic bacteria are generally available for consumers as concentrated preparations or incorporated in milk-based foods. Due to an increased interest of the market for probiotic foods as well as to meet a demand of industry for innovation, a new kind of probiotic food has been developed using table olives as a carrier. Green table olives, produced according to the Spanish-style, are obtained by a fermentation which can be carried out by spontaneous microflora, even if the use of starter cultures is desirable to obtain a more controlled process. In this regard, the selected strain Lactobacillus paracasei IMPC 2.1 of human origin was used in the dual role of starter and probiotic culture, and here we describe the different aspects which have been evaluated and solved to utilize that strain for the development of a new table olive-based probiotic food. These aspects include selection of the strain on the basis of its probiotic properties, molecular characterization, compatibility with the carrier food, and efficacy as starter. The final product meets commercial and functional requirements throughout its shelf-life.

Interaction of Bifidobacterium bifidum LMG13195 with HT29 cells influences regulatory-T-cell-associated chemokine receptor expression

Probiotics play an important role in the maintenance of the gastrointestinal barrier. In addition to direct effects on mucosal integrity, the interaction with the intestinal mucosa may have an active immunoregulatory effect. In the present work, we exposed HT29 intestinal epithelial cells to two Bifidobacterium species to determine their effect on gene expression profile, enterocyte monolayer integrity, and T-cell response. Bifidobacterium breve IPLA 20004 triggered a more pronounced increase in the transepithelial resistance of the enterocyte monolayer than Bifidobacterium bifidum LMG13195. The transcriptome profile of HT29 cells cultured in the presence of B. bifidum LMG13195 showed an increased expression of immune mediators and, interestingly, chemotactic molecules (CXCL10, CCL20, CXCL11 and CCL22) able to recruit lymphocytes. Since regulatory T cells (Treg cells) may express receptors for specific chemokines, we cultured peripheral blood mononuclear cells with supernatants of HT29 cells previously treated with Bifidobacterium strains and analyzed FOXP3 and CD25 Treg markers and CCR6, CXCR3, CCR4, and CCR3 expression on CD4(+) lymphocytes. The proportion of CD25(high) FOXP3(+) cells was significantly increased after culture with B. bifidum LMG13195-conditioned HT29 supernatant. Moreover, this treatment led to the largest amount of CCR6(+) CXCR3(-) CCR4(+) CCR3(+) CD4(+) cells expressing high levels of CD25, corresponding to the Treg population. These results suggest that soluble factors secreted after B. bifidum LMG13195 contact with intestinal epithelial cells favored the generation of CD4(+) CD25(high) lymphocytes expressing chemokine receptor Treg markers, thus making possible their recruitment to the intestinal mucosa.

Modern approaches in probiotics research to control foodborne pathogens

Foodborne illness is a serious public health concern. There are over 200 known microbial, chemical, and physical agents that are known to cause foodborne illness. Efforts are made for improved detection, control and prevention of foodborne pathogen in food, and pathogen associated diseases in the host. Several commonly used approaches to control foodborne pathogens include antibiotics, natural antimicrobials, bacteriophages, bacteriocins, ionizing radiations, and heat. In addition, probiotics offer a potential intervention strategy for the prevention and control of foodborne infections. This review focuses on the use of probiotics and bioengineered probiotics to control foodborne pathogens, their antimicrobial actions, and their delivery strategies. Although probiotics have been demonstrated to be effective in antagonizing foodborne pathogens, challenges exist in the characterization and elucidation of underlying molecular mechanisms of action and in the development of potential delivery strategies that could maintain the viability and functionality of the probiotic in the target organ.

Characterization of a probiotic-derived soluble protein which reveals a mechanism of preventive and treatment effects of probiotics on intestinal inflammatory diseases

The beneficial effects of probiotics have been demonstrated in many diseases, such as inflammatory bowel disease. The known mechanisms for probiotic action include blocking pathogenic bacterial effects, enhancing the innate immunity and decreasing pathogen-induced inflammation, and promoting intestinal epithelial cell survival, barrier function, and protective responses. We purified and cloned a Lactobacillus rhamnosus GG (LGG)-derived soluble protein, p40. This protein ameliorated cytokine-induced apoptosis in intestinal epithelial cells through activation of the EGF receptor and its down-stream target, Akt. By using special hydrogel beads to protect p40 from degradation, we showed that p40 reduced intestinal epithelial apoptosis and preserved barrier function in the colon epithelium in an EGF receptor-dependent manner, thereby preventing and treating intestinal inflammation in mouse models of colitis. Further works regarding structural analysis of p40, regulation of EGF receptor activation and immunoregulatory effects by p40 are discussed. These results may provide insights into the clinical application of probiotics for intestinal inflammatory disorders.