A Bifidobacterial pilus-associated protein promotes colonic epithelial proliferation.

Development of the human gut microbiota commences at birth, with certain bifidobacterial species representing dominant and early colonisers of the newborn gastrointestinal tract. The molecular basis of Bifidobacterium colonisation, persistence and presumed communication with the host has remained obscure. We previously identified tight adherence (Tad) pili from Bifidobacterium breve UCC2003 as an essential colonisation factor. Here, we demonstrate that bifidobacterial Tad pili also promote in vivo colonic epithelial proliferation. A significant increase in cell proliferation was detectable 5 days postadministration of B. breve UCC2003. Using advanced functional genomic approaches, bacterial strains either (a) producing the Tad2003 pili or (b) lacking the TadE or TadF pseudopilins were created. Analysis of the ability of these mutant strains to promote epithelial cell proliferation in vivo demonstrated that the pilin subunit, TadE, is the bifidobacterial molecule responsible for this proliferation response. These findings were confirmed in vitro using purified TadE protein. Our data imply that bifidobacterial Tad pili may contribute to the maturation of the naïve gut in early life through the production of a specific scaffold of extracellular protein structures, which stimulate growth of the neonatal mucosa.

Bifidobacterium breve as a delivery vector of IL-24 gene therapy for head and neck squamous cell carcinoma in vivo.

Beneficial bacteria are becoming ever more popular gene delivery method for hypoxia-tumor targeting in vivo. In this study we investigated the therapeutic effect of new recombinant Bifidobacterium breve strain expressing interleukin (IL)-24 gene (B. breve-IL24) on head and neck tumor xenograft in mice. Briefly, B. breve transformants were obtained through electro-transformation. Bacteria-tumor-targeting ability were analyzed in vivo over different time points (1, 3 and 7 days post-bacteria injection). Furthermore, the therapeutic effect of bacteria on tumor cells in vivo were analyzed as follows: 30 Balb/c nude mice bearing subcutaneous tumor were randomly divided in three groups (Drug group, green fluorescent protein (GFP) group and Saline group). The therapy lasted for 2 weeks and included B. breve-IL24 administration via tail vein for Drug group, B. breve-GFP for GFP group and phosphate buffered saline for Saline group. The tumor growth was monitored using standard caliper technique, while the apoptosis induction in vivo was analyzed by Real-time Positron Emission Tomography/Computed Tomography (PET/CT) imaging ([18F]-ML-10 tracer). At the end of the experiment, tumor tissues were collected and analyzed by western blotting. Briefly, our results suggested that our new recombinant bacterium has the capability of targeting tumor tissue in vivo. As for the therapeutic effect, our new strain has revealed to be a promising therapeutic approach against tumor growth in vivo. Briefly, higher tumor growth inhibition and higher tumor cell apoptosis induction were observed in Drug group compared with the GFP and Saline groups. To conclude, a new recombinant strain B. breve-IL24 offers a novel, safe and clinically acceptable therapeutic approach for tumor therapy in vivo.

Bifidobacterium breve reduces apoptotic epithelial cell shedding in an exopolysaccharide and MyD88-dependent manner.

Certain members of the microbiota genus Bifidobacterium are known to positively influence host well-being. Importantly, reduced bifidobacterial levels are associated with inflammatory bowel disease (IBD) patients, who also have impaired epithelial barrier function, including elevated rates of apoptotic extrusion of small intestinal epithelial cells (IECs) from villi-a process termed 'cell shedding'. Using a mouse model of pathological cell shedding, we show that mice receiving Bifidobacterium breve UCC2003 exhibit significantly reduced rates of small IEC shedding. Bifidobacterial-induced protection appears to be mediated by a specific bifidobacterial surface exopolysaccharide and interactions with host MyD88 resulting in downregulation of intrinsic and extrinsic apoptotic responses to protect epithelial cells under highly inflammatory conditions. Our results reveal an important and previously undescribed role for B. breve, in positively modulating epithelial cell shedding outcomes via bacterial- and host-dependent factors, supporting the notion that manipulation of the microbiota affects intestinal disease outcomes.

Bacteria-Mediated Hypoxia-Specific Delivery of Nanoparticles for Tumors Imaging and Therapy.

The hypoxia region in a solid tumor has been recognized as a complex microenvironment revealing very low oxygen concentration and deficient nutrients. The hypoxic environment reduces the susceptibility of the cancer cells to anticancer drugs, low response of free radicals, and less proliferation of cancer cells in the center of the solid tumors. However, the reduced oxygen surroundings provide an appreciable habitat for anaerobic bacteria to colonize. Here, we present the bacteria-mediated targeting hypoxia to offer the expandable spectra for diagnosis and therapy in cancer diseases. Two delivery approaches involving a cargo-carrying method and an antibody-directed method were designed to deliver upconversion nanorods for imaging and Au nanorods for photothermal ablation upon near-infrared light excitation for two forms of the anaerobic Bifidobacterium breve and Clostridium difficile. The antibody-directed strategy shows the most effective treatment giving stronger imaging and longer retention period and effective therapy to completely remove tumors.