Effects of yogurt ingestion on mucosal and systemic cytokine gene expression in the mouse

Modulation of cytokine gene expression in spleen and Peyer's patches by feeding dahi containing probiotic Lactobacillus casei in mice

OBJECTIVE

In present study, feeding effect of probiotic dahi containing Lactobacillus casei on immune system in terms of cytokine gene expression in the spleen and Peyer's patches of mice was evaluated.

METHODS

Animals were divided into three groups and fed with; synthetic diet [control group (CD)], dahi containing mixed dahi culture [control dahi-fed group (CDF)]; and probiotic dahi fed group (PDF) for 28 days. The mRNA levels of IL-2, IL-4, IL-6 and IFN-gamma were examined after 14 and 28 days. Total lactobacilli and lactococci counts were determined in the feces.

RESULTS

The mRNA levels of IFN-gamma in both spleen and Peyer's patches was found to be significantly increased in PDF animals after 14 and 28 days (P < 0.05) compared with CD and CDF groups. The abundance of IL-2 mRNA also increased significantly in the Peyer's patches of PDF-fed animals. No significant changes were observed in mRNA levels of IL-4 and IL-6 in both spleen and Peyer's patches during whole experimental period. Further, total fecal lactobacilli and lactococci counts in the PDF group were significantly increased during first 10 days, then remained higher up to day 28 compared to other two groups.

CONCLUSION

It is concluded that feeding probiotic dahi enhanced the expression of Th1 type cytokines (IFN-gamma and IL-2), especially in the mucosal immune organ (Peyer's patches) rather than in systemic organs (the spleen). This indicates that feeding with probiotic dahi may strengthen the host immune system and protect against the progression of various immune-mediated diseases.

Invited Review: Advances in Starter Cultures and Cultured Foods

With 2005 retail sales close to $4.8 million, cultured dairy products are driving the growth of dairy foods consumption. Starter cultures are of great industrial significance in that they play a vital role in the manufacturing, flavor, and texture development of fermented dairy foods. Furthermore, additional interest in starter bacteria has been generated because of the data accumulating on the potential health benefits of these organisms. Today, starter cultures for fermented foods are developed mainly by design rather than by the traditional screening methods and trial and error. Advances in genetics and molecular biology have provided opportunities for genomic studies of these economically significant organisms and engineering of cultures that focuses on rational improvement of the industrially useful strain. Furthermore, much research has been published on the health benefits associated with ingesting cultured dairy foods and probiotics, particularly their role in modulating immune function. The aim of this review is to describe some of the major scientific advances made in starter and non-starter lactic acid bacteria during the past 10 yr, including genomic studies on dairy starter cultures, engineering of culture attributes, advances in phage control, developments in methods to enumerate lactic acid bacteria and probiotics in dairy foods, and the potential role of cultured dairy foods in modulation of immune function.

Lactobacillus rhamnosus GG decreases TNF-alpha production in lipopolysaccharide-activated murine macrophages by a contact-independent mechanism

Animal studies and human clinical trials have shown that Lactobacillus can prevent or ameliorate inflammation in chronic colitis. However, molecular mechanisms for this effect have not been clearly elucidated. We hypothesize that lactobacilli are capable of downregulating pro-inflammatory cytokine responses induced by the enteric microbiota. We investigated whether lactobacilli diminish production of tumour necrosis factor alpha (TNF-alpha) by the murine macrophage line, RAW 264.7 gamma (NO-), and alter the TNF-alpha/interleukin-10 (IL-10) balance, in vitro. When media conditioned by Lactobacillus rhamnosus GG (LGG) are co-incubated with lipopolysaccharide (LPS) or lipoteichoic acid (LTA), TNF-alpha production is significantly inhibited compared to controls, whereas IL-10 synthesis is unaffected. Interestingly, LGG-conditioned media also decreases TNF-alpha production of Helicobacter-conditioned media-activated peritoneal macrophages. Lactobacillus species may be capable of producing soluble molecules that inhibit TNF-alpha production in activated macrophages. As overproduction of pro-inflammatory cytokines, especially TNF-alpha, is implicated in pathogenesis of chronic intestinal inflammation, enteric Lactobacillus-mediated inhibition of pro-inflammatory cytokine production and alteration of cytokine profiles may highlight an important immunomodulatory role for commensal bacteria in the gastrointestinal tract.

Interactions of lactic acid bacteria with human intestinal epithelial cells: effects on cytokine production

As a participant in the mucosal immune response, the intestinal epithelial cell must respond to a variety of stimuli, including lactic acid bacteria (LAB) consumed in the diet. The objective of this study was to compare the abilities of several strains of LAB to modulate cytokine secretion by human intestinal epithelial cell (IEC) line HT-29. Certain strains of Lactobacillus rhamnosus, Lactobacillus delbrueckii, and Lactobacillus acidophilus suppressed the production of the chemokine RANTES by stimulated HT-29 IEC, although the magnitude of this suppression varied depending on the nature of the bacterial growth medium. Similarly, specific strains showed growth condition-dependent suppression of HT-29 interleukin-8 (IL-8) production. Strain-dependent effects were also seen for the suppression of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) production. The binding of several of these bacterial strains to the HT-29 cell line was also examined. Different strains were found to have differing abilities to interact with IEC, with L. rhamnosus R0011 being the strain that generally had the most extensive effects on HT-29 cytokine production and also bound to HT-29 IEC most effectively. Modulation of IEC cytokine production has the potential to profoundly affect the mucosal microenvironment, influencing the immune response to pathogens and other ingested antigens.

Prophylactic feeding of Lactobacillus acidophilus NCFM to mice attenuates overt colonic hyperplasia

The objective of this project was to determine if the probiotic Lactobacillus acidophilus NCFM would protect mice from developing transmissible murine colonic hyperplasia (TMCH) caused by Citrobacter rodentium. Our hypothesis was that the oral administration of L. acidophilus NCFM to mice would mitigate colonic hyperplasia and modulate the host immune response. A concurrent administration (CA) study was performed by feeding mice phosphate-buffered saline (PBS), C. rodentium only, L. acidophilus NCFM only, or C. rodentium and NCFM concurrently on the same day. The mice in the CA study were not protected by the probiotic, since their mean colon sample weights (0.109 g) were significantly higher than those of the PBS controls (0.0774 g), and the hematoxylin and eosin-stained samples showed histological changes typically associated with TMCH. A prophylactic feeding (PF) study was performed by orally feeding mice PBS or NCFM once daily for 20 consecutive days; in addition, on day 7, mice were challenged with either PBS or C. rodentium. Mice in the PF study were protected when they consumed the probiotic prior to the pathogen challenge, since their mean colon sample weights (0.0812 g) were not significantly higher than those of the controls (0.0753 g). The hematoxylin and eosin-stained samples appeared similar to the control samples, and the intestinal interleukin (IL)-15 and gamma interferon (IFN-gamma) mRNA levels were reduced. L. acidophilus NCFM did attenuate overt colonic hyperplasia when fed to mice prior to challenge with C. rodentium. The mouse model used in this study enabled us to investigate the efficacy of the L. acidophilus NCFM in preventing gastrointestinal disease and is a valid model for future probiotic research.

Effects of dietary yoghurt on immunological and clinical parameters of rhinopathic patients

OBJECTIVES

To examine the immunological and clinical influence of 4 months' feeding with either yoghurt or partially skimmed milk or nothing, on 20 volunteers.

SUBJECTS

Thirteen subjects had a demonstrated allergic rhinopathy and seven were healthy subjects and participated as controls.

RESEARCH DESIGN

Either a group of seven or a group of six rhinopathic patients were fed either 450 g yoghurt or 450 g partially skimmed milk, respectively, for 4 months between March and October 1999. All subjects maintained their usual diet throughout the study. Peripheral blood mononuclear cells (PBMC) were isolated before and after the experimental period and cultured for periods of 40 and 64 h. Proliferation index assay and release of IFNgamma and IL-4 without and with PHA stimulation were assessed. Allergic rhinopathy was evaluated before and after the 4 months period by performing the nasal functionality tests (Active Anterior Rhinomanometry, Acoustic Rhinometry), the prick test, the nasal specific provocation test (NPT), the dosage of specific IgE blood levels, the evaluation of the symptomatological score and the nasal mucociliary transport test.

RESULTS

No significant change of the proliferation index was noted among the three groups. Cultured PBMC of the group fed with yoghurt released more IFNgamma and less IL-4. Cytokine plasma levels were at and remained at basal levels. Prick test, specific serum IgEs and NPT remained immodified. Muco-ciliary transport time (MCTt) and symptomatological score showed a definitive improvement after yoghurt feeding.

CONCLUSION

Yoghurt feeding appears to improve or prevent allergic recurrences in rhinopatic patients.

Effects of ingestion of yogurts containing Bifidobacterium and Lactobacillus acidophilus on spleen and Peyer's patch lymphocyte populations in the mouse

Certain probiotic lactic acid bacteria have been reported to improve immune system function. Here, the effects of ingesting yogurts on lymphocyte populations in the spleens and Peyer's patches were determined in mice. Three probiotic-supplemented yogurts containing Streptococcus thermophilus, Lactobacillus bulgaricus, Bifidobacterium, and Lactobacillus acidophilus and one conventional yogurt containing only S. thermophilus and L. bulgaricus were prepared from commercial starter cultures and used in the study. B6C3F1 female mice were fed the four different types of yogurts mixed with an AIN-93G diet in a 50:50 (wt/wt) ratio. Nonfat dry milk mixed at a 50:50 (wt/wt) ratio with AIN-93G diet was used as the control. After a 14-day feeding period, spleen and Peyer's patches were removed and lymphocytes subjected to phenotype analysis by flow cytometry. Ingestion of the four yogurts had no effect on percentages of CD8+ (cytotoxic T cells), B220+ (B cells), IgA+, or IgM+ cells in spleen or Peyer's patches. The percentage of CD4+ (T helper) cells was significantly increased in the spleens from one group of mice fed a yogurt containing Bifidobacterium and L. acidophilus, and a similar trend was found in the remaining two probiotic-supplemented yogurts. Effects on CD4+ populations were not observed in spleens of mice fed conventional yogurt or in the Peyer's patches of any of the four yogurt groups. In total, the results suggested that ingestion of conventional or probiotic-supplemented yogurts for 2 weeks had very little effect on lymphocyte distribution in the systemic or mucosal immune compartments.

Nutrition and the mucosal immune system

Gut-associated lymphoid tissue is the dominant site for the initiation of mucosal immune response. Mucosal immunity depends on regulatory signals; nutritional elements, including fats, amino acids, and micronutrients, are critical cofactors for these signals. Nutrients specifically affect lymphocyte influx and migration, mononuclear cell activation, and the differentiated expression of immune response. The molecular basis of nutrient action has been shown to involve effects on receptor regulation, adhesion molecule expression, and the pattern of cytokine production. The gastrointestinal mucosal immune system is the major site for host interaction with microbes and provides a barrier against systemic access for food antigens and microbes. Nutrient metabolism has unique and direct impact on the host defense system of gut-associated lymphoid tissue and therefore has potential for widely disseminated impact on systemic immune response.

Viability of bifidobacteria in commercial dairy products during refrigerated storage

Commercial milk and two brands of yogurt containing bifidobacteria were obtained from retail outlets. All products were evaluated for viability of bifidobacteria and lactic acid bacteria during refrigerated storage at 4 degrees C. Milk was evaluated at 9, 6, and 3 days prior and past its expiration date. The yogurts were evaluated at 3, 2, and 1 week prior and past their expiration. Viability of bifidobacteria and lactic acid bacteria in milk and yogurt remained above 10(6) CFU/ml or g until the expiration date of the respective products. This microbial concentration is the recommended minimum dose to receive the health benefits of these organisms.

Probiotic immunomodulation in health and disease

Probiotics, microorganisms that have a favorable influence on physiologic and pathological processes of the host by their effect on the intestinal flora, may play a role in improving human health. One of the putative effects is the modulation of immune function. Thus, the mucosal immune system and methods to assess its function are reviewed briefly. Probiotic modulation of humoral, cellular and nonspecific immunity is reviewed, with emphasis placed on immune response in disease models. There are very few reports of human intervention studies with probiotics. However, some of the possible future directions for research with respect to probiotics, immunity, and human health are discussed. Although the application of probiotics has demonstrated trends with respect to altered aspects of immune response, the underlying mechanisms by which that occurs are unclear.