Bacteroides fragilis induce necrosis on mice peritoneal macrophages: In vitro and in vivo assays

Intestinal microbiome and lymphoma development

The intestinal microbiota and gut immune system must communicate to maintain a balance between tolerance and activation. Our immune system protects us from pathogenic microbes at the same time that our bodies are host to trillions of microbes, symbionts, mutualists, and some that are essential to human health. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue lymphoma have been shown to be caused by the presence of certain bacteria. Animal models have played an important role in elucidating the causation and establishing the mechanism of bacteria-induced mucosal-associated lymphoid tissue lymphoma. In this review, we discuss different ways that animal models have been applied to investigate links between the gut microbiota and lymphoma and have helped to reveal the mechanisms of microbiota-induced lymphoma. Although there is a paucity of published studies demonstrating the interplay between the microbiota and lymphoma development, we believe that the connection is real and that it can be exploited in the future to enhance our understanding of causation and to improve the prognosis and treatment of lymphoma.

Lymphoma caused by intestinal microbiota

The intestinal microbiota and gut immune system must constantly communicate to maintain a balance between tolerance and activation: on the one hand, our immune system should protect us from pathogenic microbes and on the other hand, most of the millions of microbes in and on our body are innocuous symbionts and some can even be beneficial. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue (MALT) lymphoma have been shown to be caused by the presence of certain bacteria. Animal models played an important role in establishing causation and mechanism of bacteria-induced MALT lymphoma. In this review we discuss different ways that animal models have been applied to establish a link between the gut microbiota and lymphoma and how animal models have helped to elucidate mechanisms of microbiota-induced lymphoma. While there are not a plethora of studies demonstrating a connection between microbiota and lymphoma development, we believe that animal models are a system which can be exploited in the future to enhance our understanding of causation and improve prognosis and treatment of lymphoma.

Bifidobacterium CECT 7765 improves metabolic and immunological alterations associated with obesity in high-fat diet-fed mice

OBJECTIVES

To evaluate the effects of administration of Bifidobacterium pseudocatenulatum CECT 7765 on metabolic and immune alterations in obese mice.

DESIGN AND METHODS

Adult male wild-type C57BL-6 mice were fed a standard diet or high-fat diet (HFD), supplemented or not with B. pseudocatenulatum CECT 7765 for 7 weeks. The assessments included biochemical and immunological parameters, insulin resistance, glucose tolerance, histology of liver, white-adipose and intestinal tissues, immunocompetent cell functions, and microbiota-related features.

RESULTS

B. pseudocatenulatum CECT 7765 reduced serum cholesterol, triglyceride, and glucose levels and decreased insulin resistance and improved glucose tolerance in obese mice. This strain reduced serum levels of leptin, interleukin (IL)-6 and monocyte chemotactic protein-1, while increased those of IL-4 in HFD-fed mice. B. pseudocatenulatum CECT7765 reduced liver steatosis and the number of larger adipocytes and number of fat micelles in enterocytes of obese mice. The strain also improved the function of macrophages and dendritic cells in relation to phagocytosis, cytokine production, and induction of T-lymphocyte proliferation. The strain administration increased bifidobacteria and reduced enterobacteria and the inflammatory properties of the gut content in HFD-fed mice.

CONCLUSION

B. pseudocatenulatum CECT 7765 was shown to ameliorate both metabolic and immunological dysfunctions related to obesity in HFD-fed mice.

Bacteroides uniformis CECT 7771 ameliorates metabolic and immunological dysfunction in mice with high-fat-diet induced obesity

BACKGROUND

Associations have been made between obesity and reduced intestinal numbers of members of the phylum Bacteroidetes, but there is no direct evidence of the role these bacteria play in obesity. Herein, the effects of Bacteroides uniformis CECT 7771 on obesity-related metabolic and immune alterations have been evaluated.

METHODS AND FINDINGS

Adult (6-8 week) male wild-type C57BL-6 mice were fed a standard diet or a high-fat-diet HFD to induce obesity, supplemented or not with B. uniformis CECT 7771 for seven weeks. Animal weight was monitored and histologic, biochemical, immunocompetent cell functions, and features of the faecal microbiota were analysed after intervention. The oral administration of B. uniformis CECT 7771 reduced body weight gain, liver steatosis and liver cholesterol and triglyceride concentrations and increased small adipocyte numbers in HFD-fed mice. The strain also reduced serum cholesterol, triglyceride, glucose, insulin and leptin levels, and improved oral tolerance to glucose in HFD fed mice. The bacterial strain also reduced dietary fat absorption, as indicated by the reduced number of fat micelles detected in enterocytes. Moreover, B. uniformis CECT 7771 improved immune defence mechanisms, impaired in obesity. HFD-induced obesity led to a decrease in TNF-α production by peritoneal macrophages stimulated with LPS, conversely, the administration of B. uniformis CECT 7771 increased TNF-α production and phagocytosis. Administering this strain also increased TNF-α production by dendritic cells (DCs) in response to LPS stimulation, which was significantly reduced by HFD. B. uniformis CECT 7771 also restored the capacity of DCs to induce a T-cell proliferation response, which was impaired in obese mice. HFD induced marked changes in gut microbiota composition, which were partially restored by the intervention.

CONCLUSIONS

Altogether, the findings indicate that administration of B. uniformis CECT 7771 ameliorates HFD-induced metabolic and immune dysfunction associated with intestinal dysbiosis in obese mice.