Evaluation of vitamin-producing and immunomodulatory lactic acid bacteria as a potential co-adjuvant for cancer therapy in a mouse model.

AIMS: To evaluate a mixture of selected lactic acid bacteria (LAB) (a riboflavin-producer, a folate-producer and an immunomodulatory strain) as co-adjuvant for 5-fluorouracil (5-FU) chemotherapy in cell culture and using a 4T1 cell animal model of breast cancer. METHODS AND RESULTS: The viability of Caco-2 cells exposed to 5-FU and/or LAB was analysed. Mice bearing breast tumour were treated with 5-FU and/or LAB. Tumour growth was measured. Intestinal mucositis (IM) was evaluated in small intestine; haematological parameters and plasma cytokines were determined. The bacterial mixture did not negatively affect the cytotoxic activity of 5-FU on Caco-2 cells. The LAB mixture attenuated the IM and prevented blood cell decreases associated with 5-FU treatment. Mice that received 5-FU and LAB mixture decreased tumour growth and showed modulation of systemic cytokines modified by both tumour growth and 5-FU treatment. The LAB mixture by itself delayed tumour growth. CONCLUSIONS: The mixture of selected LAB was able to reduce the side-effects associated with chemotherapy without affecting its primary anti-tumour activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This bacterial mixture could prevent the interruption of conventional oncologic therapies by reducing undesirable side-effects. In addition, this blend would provide essential nutrients (vitamins) to oncology patients.

Recent update on lactic acid bacteria producing riboflavin and folates: application for food fortification and treatment of intestinal inflammation.

Lactic acid bacteria (LAB), widely used as starter cultures for the fermentation of a large variety of food, can improve the safety, shelf life, nutritional value and overall quality of the fermented products. In this regard, the selection of strains delivering health-promoting compounds is now the main objective of many researchers. Although most LAB are auxotrophic for several vitamins, it is known that certain strains have the capability to synthesize B-group vitamins. This is an important property since humans cannot synthesize most vitamins, and these could be obtained by consuming LAB fermented foods. This review discusses the use of LAB as an alternative to fortification by the chemical synthesis to increase riboflavin and folate concentrations in food. Moreover, it provides an overview of the recent applications of vitamin-producing LAB with anti-inflammatory/antioxidant activities against gastrointestinal tract inflammation. This review shows the potential uses of riboflavin and folates producing LAB for the biofortification of food, as therapeutics against intestinal pathologies and to complement anti-inflammatory/anti-neoplastic treatments.

Milk fermented by Lactobacillus casei CRL431 administered as an immune adjuvant in models of breast cancer and metastasis under chemotherapy.

Chemotherapy is the most common treatment for breast cancer and its metastasis; however, it affects the patients' quality of life. Previously, it was demonstrated that milk fermented by Lactobacillus casei CRL431 (probiotic fermented milk (PFM)) exerted benefits against breast cancer metastasis by modulating the immune response in a mouse model. The aim of this work was to evaluate PFM administration on the side effects of capecitabine and on its anti-tumour/anti-metastatic effects. In vitro, 4T1 breast cancer cells were treated with capecitabine in the presence of immune cells' conditioned media from mice administered with PFM. Cell viability was evaluated by MTT assay. In vivo, BALB/c mice (healthy, bearing breast cancer or with potential metastasis) were treated or not with capecitabine and administered with PFM. Blood cell counts, intestinal damages, lung histology and serum cytokines were evaluated. Results showed that capecitabine's toxicity on 4T1 cells was improved by the immune cells from mice that received PFM when the lower dose of capecitabine was evaluated. PFM reduced capecitabine side effects in all the mouse models and decreased intestinal mucositis and mortality. PFM administration to mice under chemotherapy maintained the anti-cancer/anti-metastasis effect of capecitabine with similar or decreased values for serum IL-10 and TNF-α and decreased IL-6, a cytokine related to poor prognosis in advanced cancer patients. In addition, PFM by itself reduced metastasis without side effects and improved the host's immune response. PFM has a potential to be administered as an immune adjuvant in patients under chemotherapy without affecting the treatment. KEY POINTS: • Milk fermented by L. casei CRL431 (PFM) diminished capecitabine side effects. • Capecitabine's toxicity on 4T1 cells was improved by the PFM-stimulated immune cells. • PFM maintained anti-cancer/anti-metastasis effect of capecitabine in mouse models. Graphical abstract.

Effect of riboflavin-producing bacteria against chemically induced colitis in mice.

AIM: To assess the anti-inflammatory effect associated with individual probiotic suspensions of riboflavin-producing lactic acid bacteria (LAB) in a colitis murine model. METHODS AND RESULTS: Mice intrarectally inoculated with trinitrobenzene sulfonic acid (TNBS) were orally administered with individual suspensions of riboflavin-producing strains: Lactobacillus (Lact.) plantarum CRL2130, Lact. paracasei CRL76, Lact. bulgaricus CRL871 and Streptococcus thermophilus CRL803; and a nonriboflavin-producing strain or commercial riboflavin. The extent of colonic damage and inflammation and microbial translocation to liver were evaluated. iNOs enzyme was analysed in the intestinal tissues and cytokine concentrations in the intestinal fluids. Animals given either one of the four riboflavin-producing strains showed lower macroscopic and histologic damage scores, lower microbial translocation to liver, significant decreases of iNOs+ cells in their large intestines and decreased proinflammatory cytokines, compared with mice without treatment. The administration of pure riboflavin showed similar benefits. Lact. paracasei CRL76 accompanied its anti-inflammatory effect with increased IL-10 levels demonstrating other beneficial properties in addition to the vitamin production. CONCLUSION: Administration of riboflavin-producing strains prevented the intestinal damage induced by TNBS in mice. SIGNIFICANCE AND IMPACT OF THE STUDY: Riboflavin-producing phenotype in LAB represents a potent tool to select them for preventing/treating IBD.

Folate-producing lactic acid bacteria reduce inflammation in mice with induced intestinal mucositis.

AIM: To evaluate two folate-producing strains, Streptococcus (Strep.) thermophilus CRL 808 and Strep. thermophilus CRL 415, against chemically induced mucositis in mice. METHODS AND RESULTS: In vitro assays with Caco-2 cells were performed to evaluate the effect of the bacteria in the presence of 5-fluorouracil (5-FU). For in vivo studies, mice were daily injected with 5-FU to induce intestinal mucositis (IM) and orally administered with folate-producing strains during 6 days. Clinical symptoms, histological parameters and cytokine profiles were assessed. The results showed that Strep. thermophilus CRL 808 increased the cytotoxicity of 5-FU against Caco-2 cells. Administration of this strain in mice with chemically induced IM resulted in a reduction in diarrhoea score and restoration of the intestinal architecture. Cytokine analysis showed that the anti-inflammatory effect by the bacterium is not associated with an immune mechanism. Regarding Strep. thermophilus CRL 415, no improvements were observed in any of the parameters evaluated. CONCLUSION: The administration of the folate-producing Strep. thermophilus CRL 808 has the potential to prevent IM induced by 5-FU in mice. SIGNIFICANCE AND IMPACT OF THE STUDY: Folate-producing LAB could be used in chemotherapy patients to reduce the symptoms of IM, improve their nutritional status and increase the effectiveness of 5-FU.

Soyamilk fermented with riboflavin-producing Lactobacillus plantarum CRL 2130 reverts and prevents ariboflavinosis in murine models.

It has been previously shown that Lactobacillus plantarum CRL 2130 is able to produce riboflavin in soyamilk. The aim of the present study was to evaluate the efficiency of this riboflavin-bio-enriched soyamilk to revert and/or prevent the nutritional deficiency of riboflavin using different animal models. When used to supplement the diets of previously depleted animals, it was shown that the growth, riboflavin status and morphology of the small intestines reverted to normal parameters and were similar to animals supplemented with commercial riboflavin. In the prevention model, the same tendency was observed, where animals that received soyamilk fermented with L. plantarum CRL 2130 did not show signs of riboflavin deficiency. This new bio-fortified soya-based product could be used as part of normal diets to provide a more natural alternative to mandatory fortification with riboflavin for the prevention of its deficiency.

Development of a potential probiotic yoghurt using selected anti-inflammatory lactic acid bacteria for prevention of colitis and carcinogenesis in mice.

AIMS: To evaluate the beneficial properties of a potentially probiotic yoghurt obtained by the fermentation of two selected anti-inflammatory bacterial strains using in vivo mouse models of intestinal inflammation and colon carcinogenesis. METHODS AND RESULTS: Yoghurt was administered to mice suffering chemically induced intestinal inflammation or colon carcinogenesis. It was shown that this novel yoghurt was able to prevent local inflammation in the intestines of mice through a regulation of the immune response, prevent macroscopic and histological damages, and prevent colon carcinogenesis through an anti-inflammatory response. CONCLUSIONS: The developed yoghurt showed in vivo anti-inflammatory properties by modulation of the host immune response for the prevention of colon inflammation and carcinogenesis. SIGNIFICANCE AND IMPACT OF THE STUDY: This new yoghurt could thus be considered a probiotic food and be useful as a complement to current treatment protocols for inflammatory bowel diseases and colon cancer, a first since there are no current functional foods specifically oriented for these patients.

Comparative study of the protective capacity against Salmonella infection between probiotic and nonprobiotic Lactobacilli.

AIMS: To investigate the immunoprotective ability of three Lactobacilli strains against Salmonella enterica serovar Typhimurium in a mouse model. To identify the probiotic properties involved in the protection against infection caused by this pathogen. METHODS AND RESULTS: The immunomodulatory effect of three different lactobacilli strains: Lactobacillus (Lact.) casei CRL 431 (probiotic bacterium), Lact. delbrueckii subsp. bulgaricus CRL 423 (Lact. bulgaricus) and Lact.acidophilus CRL 730 was compared using a mouse model of Salmonella infection. Lactobacillus casei continuous administration improved animal survival, diminished pathogen spreading outside the intestine, attenuated the intestinal inflammation, modulated cytokine profile previous and postinfection and increased the expression and secretion of IgA in the gut. Additionally, the administration of this lactobacilli increased peritoneal, Peyer's patches and spleen macrophages' phagocytic activity in healthy mice and monocyte chemotactic protein (MCP-1) released by intestinal epithelial cells in an in vitro assay. Although Lact. acidophilus increased the number of IgA-secreting cells previous and postinfection, and Lact. bulgaricus increased MCP-1 released by intestinal epithelial cells and the phagocytic activity of macrophages, these effects alone were not enough to confer protection against Salmonella Typhimurium infection in mouse. CONCLUSIONS: Probiotic strain Lact. casei CRL 431 was the one that induced protection against Salmonella, by increasing the intestinal barrier function and by decreasing the local inflammatory response. SIGNIFICANCE AND IMPACT OF THE STUDY: Salmonella spp. constitutes an important agent of foodborne diseases in the world. Not all lactobacilli, even with some immunostimulating properties at gut level, can protect against Salmonella infection. Lactobacillus casei CRL 431, a probiotic bacterium, could be useful as an oral mucosal adjuvant of the immune system to improve gut health, especially in the prevention or amelioration of Salmonella infections. We demonstrated that there is not a unique mechanism by which this protective effect was exerted.

Streptomyces genus as a source of probiotics and its potential for its use in health.

The effect of a probiotic on gut microbiota depends not only on the species of microorganism but specifically on the strain. In human beings, as in other animals, specific probiotics have been associated with numerous beneficial properties, which include weight modulation (gain or loss), immune modulation, and prevention of many disorders such as lactose intolerance, cardiovascular diseases, and antibiotic-associated diarrhoea. Streptomyces are an essential group of soil bacteria in the Actinomycetes family. They are related to producing a wide range of secondary metabolites known for their beneficial effects on human health. However, according to the human microbiome analysis, a lower prevalence of Streptomyces genus exists than in other non-human microbiomes. This difference can be associated with current lifestyles. In this article, we review the benefits associated with different compounds produced by Streptomyces, with a particular focus on the production of exopolysaccharides, antibiotics, and other secondary metabolites and the potential innovative use of Streptomyces spp. as probiotics.

ß-Casein hydrolysate generated by the cell envelope-associated proteinase of Lactobacillus delbrueckii ssp. lactis CRL 581 protects against trinitrobenzene sulfonic acid-induced colitis in mice.

Lactobacillus delbrueckii ssp. lactis CRL 581, a thermophilic lactic acid bacterium used as a starter culture for the manufacture of several fermented dairy products, possesses an efficient proteolytic system that is able to release a series of potentially bioactive peptides (i.e., antihypertensive and phosphopeptides) from α- and ß-caseins. Considering the potential beneficial health effects of the peptides released by L. delbrueckii ssp. lactis CRL 581 from milk proteins, the aim of this work was to analyze the anti-mutagenic and anti-inflammatory properties of the casein hydrolysates generated by the cell envelope-associated proteinase of this bacterium. The ability of α- and ß-casein hydrolysates to suppress the mutagenesis of a direct-acting mutagen 4-nitroquinoline-N-oxide on Salmonella typhimurium TA 98 and TA 100 increased concomitantly with the time of casein hydrolysis. The anti-inflammatory effect of the ß-casein hydrolysate was evaluated using a trinitrobenzene sulfonic acid (TNBS)-induced Crohn's disease murine model. The hydrolysate was administered to mice 10 d before the intrarectal inoculation of TNBS. The mice that received ß-casein hydrolysate previously to TNBS showed decreased mortality rates, faster recovery of initial body weight loss, less microbial translocation to the liver, decreased ß-glucuronidase and myeloperoxidase activities in the gut, and decreased colonic macroscopic and microscopic damage compared with the animals that did not receive this hydrolysate. In addition, ß-casein hydrolysate exerted a beneficial effect on acute intestinal inflammation by increased interleukin 10 and decreased IFN-γ production in the gut. Our findings are consistent with the health-promoting attributes of the milk products fermented by L. delbrueckii ssp. lactis CRL 581 and open up new opportunities for developing novel functional foods.

Maternal dietary omega-3 deficiency worsens the deleterious effects of prenatal inflammation on the gut-brain axis in the offspring across lifetime.

Maternal immune activation (MIA) and poor maternal nutritional habits are risk factors for the occurrence of neurodevelopmental disorders (NDD). Human studies show the deleterious impact of prenatal inflammation and low n-3 polyunsaturated fatty acid (PUFA) intake on neurodevelopment with long-lasting consequences on behavior. However, the mechanisms linking maternal nutritional status to MIA are still unclear, despite their relevance to the etiology of NDD. We demonstrate here that low maternal n-3 PUFA intake worsens MIA-induced early gut dysfunction, including modification of gut microbiota composition and higher local inflammatory reactivity. These deficits correlate with alterations of microglia-neuron crosstalk pathways and have long-lasting effects, both at transcriptional and behavioral levels. This work highlights the perinatal period as a critical time window, especially regarding the role of the gut-brain axis in neurodevelopment, elucidating the link between MIA, poor nutritional habits, and NDD.

Adjuvant effect of a probiotic fermented milk in the protection against Salmonella enteritidis serovar typhimurium infection: mechanisms involved.

Probiotics may offer protection against Salmonella enteritidis serovar Typhimurium infection via different mechanisms. The aim of this study is to investigate, using mouse models, the effect of the administration of fermented milk containing the probiotic bacteria L. casei DN-114 001 in the protection against Salmonella enteritidis serovar Typhimurium when this product is administered continuously before and after infection or only post-infection. The adjuvant effect of this probiotic fermented milk (PFM) against S. Typhimurium was also evaluated in newborn mice, whose mothers received the PFM during the suckling period or their offspring after weaning. The results obtained showed that PFM administration after salmonella infection was useful to decrease the severity of the infection. The best effect was obtained with continuous PFM administration. In the newborn mice model, PFM administration to the newborn mice after weaning showed the best effect against the pathogen. PFM administration to the mother during the suckling period was beneficial against this enterophatogen when their offspring did not receive probiotics after weaning. Continuous PFM administration to adult mice (before and after infection) was important to maintain the intestinal barrier and the immune surveillance in optimal conditions to diminish the pathway of entrance of salmonella and the spread of this pathogen to deeper tissues. In the newborn mice model, it was observed that PFM administration to the offspring after weaning or their mother during the suckling period had a protective effect against salmonella infection, however, in the mice from mothers that received PFM during nursing which were fed with PFM after weaning, we found a down regulated immune maturity that was not protective against this infection.

Milk fermented by Lactobacillus casei CRL431 modifies cytokine profiles associated to different stages of breast cancer development in mice.

Breast cancer is one of the leading causes of death worldwide. It is recognised that immune system influences its promotion, progression, and metastasis, as well as their responsiveness to therapies. Previously, it was reported that milk fermented by Lactobacillus casei CRL431 decreased tumour growth and metastasis in a mouse breast cancer model, through the modulation of the host immune response. The aim of the present work was to analyse the systemic immune response induced by the administration of probiotic fermented milk (PFM) at different stages of cancer development, evaluating cytokines produced by splenocytes stimulated in vitro with 4T1 tumour cells, or its conditioned medium (CM). Groups of healthy mice and mice bearing 4T1 tumour or suffering metastasis after tumour surgery were studied. Results showed that at the early stages, PFM maintained pro-inflammatory response associated to the delay or the inhibition of tumour growth. PFM administration to mice bearing tumour maintained an important inflammatory response; however, in contrast to the milk group, this response was regulated to avoid exacerbation of inflammation. In the metastasis model, the benefits of PFM were associated to avoid the immunosuppression associated to high interleukin-10 levels. In conclusion, as cancer cells induce modifications of the immune response to favour their own growth at each stage of cancer development, PFM administration stimulated different profile of cytokines to respond to these modifications and fight against cancer cells.

Beneficial effects of Saccharomyces cerevisiae RC016 in weaned piglets: in vivo and ex vivo analysis.

Probiotics represents an alternative to replace antibiotics as growth promoters in animal feed and are able to control enteric bacterial diseases and to improve gut immunity. Saccharomyces cerevisiae RC016 showed previously inhibition/coagregation of pathogens) and mycotoxins adsorbent ability (aflatoxin B1, ochratoxin A and zearalenone). The aim of this work was to evaluate beneficial properties of S. cerevisiae RC016 in a non-inflammatory in vivo model in weaned piglets and in an intestinal inflammation ex vivo model induced by the mycotoxin deoxynivalenol (DON). Secretory immunoglobulin A (s-IgA) levels, intestinal cytokines, goblet cells and production parameters were evaluated in a pig model. For the in vivo assays, twelve pigs were weaned at 21 days and assigned to two groups: Control (n=6) and Yeast (n=6). Animals received yeast strain for three weeks. After 22 days the small intestine was recovered for determination of goblet cells and s-IgA. For the ex vivo assay, jejunal explants were obtained from 5 weeks old crossbred piglets and treated as follow: (1) control; (2) treated for 3 h with 10 µM DON used as an inflammatory stressor; (3) incubated with 107 cfu/ml yeast strain; (4) pre-incubated 1 h with 107 cfu/ml yeast strain and then treated for 3 h with 10 µM DON. CCL20, interleukin (IL)-1ß, IL-8 and IL-22 gene expression was determined by qPCR. Oral administration of S. cerevisiae RC016 increased s-IgA, the number of goblet cells in small intestine and all the growth parameters measured. In the ex vivo model, the cytokine profile studied showed a potential anti-inflammatory effect of the administration of the yeast. In conclusion, S. cerevisiae RC016 is a promising candidate for feed additives formulation to improve animal growth and gut immune system. This yeast strain could be able to improve the gut health through counteracting the weaning-associated intestinal inflammation in piglets.

Effect of long-term continuous consumption of fermented milk containing probiotic bacteria on mucosal immunity and the activity of peritoneal macrophages.

The effect of the long-term administration of commercial fermented milk containing probiotic bacteria in the mucosal immune response and peritoneal macrophages was analyzed. BALB/c mice were fed with fermented milk for 98 consecutive days. Small and large intestines were removed for histology; IgA, CD4, CD8 cells and cytokines-producing cells were counted. The influence on the immune cells associated with bronchus and mammary glands as well as on peritoneal macrophages was also analyzed. Continuous oral administration of fermented milk increased IgA+ cells in both parts of the intestine (small and large intestine). IL-10, a regulatory cytokine, increased in the intestinal cells in most samples. TNFalpha, IFNgamma and IL-2 producing cells were also enhanced. Values for CD4 and CD8(+) cell populations in lamina propria of the intestine were increased in relation to the control throughout the assay. No modifications in the histology of intestines were observed. Long-term consumption of fermented milk enhanced intestinal mucosa immunity, mediated by IgA+ cells and by cytokine production. This improvement of gut immunity was maintained and down-regulated by cytokines such as IL-10, preventing gut inflammatory immune response. The effect of this fermented milk on mucosal sites distant to the gut, such as bronchus and mammary glands, showed that in both tissues the increase in IgA+ cells was only observed at the beginning of the continuous consumption and no modifications in the number of cytokine positive cells were found. Similar observations were found when phagocytic activity of peritoneal macrophages was measured. It was demonstrated that the most evident effect of long-term consumption of fermented milk was observed in the intestine. Immunodulatory effects and the maintenance of intestinal homeostasis without secondary effects after long-term administration of fermented milk were also observed.

Study of immune cells involved in the antitumor effect of kefir in a murine breast cancer model.

Administration of kefir and a kefir cell-free fraction (KF) to mice injected with breast tumor cells produced, locally in the mammary gland, different profiles of cells secreting cytokines. Here, the immune cell populations in mammary glands affected by the cyclic consumption of kefir or KF for 2 or 7 d were evaluated using a breast tumor model. Apoptosis was also assayed as another mechanism involved in tumor growth delay. The rate development of tumor cells, IgA(+) cells, and CD4+ and CD8+ T lymphocytes was monitored in mammary gland tissues. The number of Bcl-2(+) cells in the mammary gland was compared with the apoptosis observed in the tumor. Two-day cyclical administration of both products delayed tumor growth and increased the number of IgA(+) cells in the mammary gland. Changes in the balance between CD4+ and CD8+ cells in the mammary gland were observed in mice from the group fed KF cyclically for 2 d, such that the number of CD4+ cells increased when the number of CD8+ cells remained constant. Mice that received 2-d cyclic administration of KF showed significant increases in the number of apoptotic cells and decreases in Bcl-2(+) cells in the mammary gland, compared with the tumor control group. The present study allows a better understanding of the mechanisms (immune and nonimmune) involved in the antitumor effect observed in mice administered kefir or KF. The importance of nonmicrobial components released during milk fermentation to obtain the beneficial antitumor effects is also reported.

Evaluation of the effect of soymilk fermented by a riboflavin-producing Lactobacillus plantarum strain in a murine model of colitis.

Inflammatory bowel diseases (IBD) are idiopathic diseases of the gastrointestinal tract characterised by recurrent inflammation that require lifelong treatments. It has been shown that certain strains of lactic acid bacteria (LAB) can produce specific health-promoting compounds in foods or in the gastrointestinal tract that can in turn prevent and/or treat IBD. This study was designed to evaluate the possible therapeutic potential of soymilk fermented by the riboflavin-producing strain Lactobacillus plantarum CRL 2130 in a trinitrobenzene sulfonic induced colitis mouse model. Mice that received soymilk fermented by L. plantarum CRL 2130 showed a decrease in weight loss, lower damage scores in their large intestines, lower microbial translocation to liver and decreased cytokines levels in their intestinal fluids compared to animals that received unfermented soymilk or soymilk fermented by a non-riboflavin-producing L. plantarum strain. This is the first report that demonstrates that a riboflavin-producing LAB was able to prevent experimental colitis in a murine model.

Lactobacillus rhamnosus RC007 intended for feed additive: immune-stimulatory properties and ameliorating effects on TNBS-induced colitis.

Lactobacillus rhamnosus RC007 is a potential probiotic bacterium that can exert beneficial effects as supplement for animal feed, by improving the immune status in healthy host, and by providing therapeutic benefits to infected/inflamed animals. The aim of the present work was to evaluate in vivo the beneficial properties of L. rhamnosus RC007, intended for animal feed, when administered to healthy and trinitro-benzene-sulfonic-acid (TNBS) colitis induced BALB/c mice. The administration of L. rhamnosus RC007 to healthy mice during 10 days increased the phagocytic activity of peritoneal macrophages and the number of immunoglobulin A+ cells in the lamina proper of the small intestine. Significant increases of monocyte chemotactic protein 1, interleukin (IL)-10 and tumour necrosis factor alpha (TNF-α) concentrations, and in the ratio between anti- and pro-inflammatory cytokines (IL-10/TNF-α) were observed in intestinal fluids after administration of bacteria. In the inflammation model, less body weight loss, macroscopic and histological damages in the large intestine were accompanied by increased IL-10/TNF-α ratio in the intestinal fluids of mice from the L. rhamnosus-TNBS group when compared to the TNBS group. In a healthy host, the oral administration of L. rhamnosus RC007 kept the gut immune system stimulated allowing a faster response to noxious stimulus. Mice that received L. rhamnosus RC007 also decreased the severity of the intestinal inflammation.

Gut-borne Saccharomyces cerevisiae, a promising candidate for the formulation of feed additives, modulates immune system and gut microbiota.

The aim was to evaluate the effect of Saccharomyces cerevisiae RC016 on immune parameters and gut microbiota in healthy mice. Animals received S. cerevisiae RC016 for 10 days. Microbial translocation to liver and changes in some bacterial populations in caecum were determined. Immune stimulation was assessed at gut level (measure ofimmunoglobulin A (IgA)+ cells and luminal cytokine profile) and by evaluating the activity of peritoneal macrophages. Oral administration of S. cerevisiae RC016 did not induce microbial translocation to liver. Mice that received yeast increased the number of IgA+ cells in their intestines, the phagocytic activity of peritoneal macrophages and decreased tumour necrosis factor alpha (TNF-α) levels in the small intestine with increases of interleukin-10/TNF-αratio. Administration of S. cerevisiae RC016 caused the decline of a logarithmic unit for Enterobacteriaceae counts compared to the control. The immune and gut microbiota modulation observed demonstrates that S. cerevisiae RC016 is a promising candidate for the formulation of feed additives to improve animal productivity. The beneficial in vivo effects observed for the potential probiotic S. cerevisiae RC016 with previously reported mycotoxin-bindingproperties, demonstrated that this strain could be suitable to be included in a novel product to improve animalproductivity, with both probiotic and mycotoxin-binding properties. However, studies in the specific host will be necessary to confirm this potential.

Effect of breast feeding time on physiological, immunological and microbial parameters of weaned piglets in an intensive breeding farm.

The aim of this work was to study the long-lasting consequences of different weaning age on physiological, immunological and microbiological parameters of weaned piglets. Piglets were weaned at 14 days (14W) or 21 days (21W). Blood samples were taken for IgG and cortisol determination on preweaning day and at 4; 20 and 40 post-weaning days. Three animals of each group were sacrificed. Small intestines for morphometric studies and secretory-IgA determination in fluid were taken. The cecum was obtained for enterobacteria, lactobacilli and total anaerobes enumeration. A significant decrease in piglet's plasma IgG concentrations was observed immediately after weaning and no differences were found between 14W and 21W. An increase in intestinal S-IgA was observed according to piglet's age. This increase was significantly higher in piglets 14W compared to piglets 21W. Animals from 14W group showed a decrease in villus length and in the number of goblet cells and intraepithelial lymphocytes. Other parameters were not affected by the weaning age. A short-term increase in cortisol was observed after weaning in both experimental groups. Enterobacteria decreased significantly after weaning in both groups, reaching values of weaning after 40 days. Lactobacilli counts decreased in both groups after weaning; however their counts were always higher than those obtained for enterobacteria. No differences were observed between 14W and 21W with regards to counts of anaerobes. The shortening of breast feeding time would favor an early synthesis of intestinal S-IgA after weaning. The changes observed in the microbiota could decrease postweaning enteric infections. However, early weaning induced negative effects on the cells of gut innate immunity and villi atrophy. This work provides knowledge about advantages and disadvantages at different weaning and long-lasting consequences on pig health. It is critical that swine producers become aware of the biological impacts of weaning age, so as to be able to decide the appropriate management strategies according to their facilities and rearing environment.