Increased mRNA expression of interferon-induced Mx1 and immunomodulation following oral administration of IFN-α2b-transformed B. longum to mice

Isolation of Limosilactobacillus mucosae G01 with inhibitory effects on porcine epidemic diarrhea virus in vitro from Bama pig gastroenteritis

Porcine epidemic diarrhea virus (PEDV) is responsible for causing fatal watery diarrhea in piglets, resulting in significant economic losses within the pig farming industry. Although vaccination is currently employed as a preventive measure, certain vaccines do not provide complete protection against PEDV field strains. Probiotics present a promising alternative due to their ability to regulate intestinal flora, enhance host immunity, and improve resistance against pathogenic microorganisms. We isolated six lactic acid bacteria (LAB) from the fecal microorganisms of Bama pigs, compared to Limosilactobacillus mucosae DSM13345 of the same genus in which Limosilactobacillus mucosae G01 (L. mucosae G01) proved to have a potent anti-PEDV effect. In a comprehensive manner, L. mucosae G01 significantly augmented the phosphorylation of IRF3 in IPEC-J2 cells, resulting in the induction of interferons (IFN α, IFN β, IFN λ1, and IFN λ3) and subsequent upregulation of interferon-stimulated genes (ISGs) (MX1, MX2, OAS1, and ZAP) in a dose-dependent fashion, consequently leading to the mitigation of PEDV replication. These findings underscore the promising prospects of L. mucosae G01 as a naturally derived substitute for combating PEDV and other enteric coronavirus infections.

Feasibility between Bifidobacteria Targeting and Changes in the Acoustic Environment of tumor Tissue for Synergistic HIFU

High intensity focused ultrasound (HIFU) has been recently shown as a rapidly developing new technique for non-invasive ablation of local tumors whose therapeutic efficiency can be significantly improved by changing the tissue acoustic environment (AET). Currently, the method of changing AET is mainly to introduce a medium with high acoustic impedance, but there are some disadvantages such as low retention of the introduced medium in the target area and a short residence time during the process. In our strategy, anaerobic bacterium Bifidobacterium longum (B. longum) which can colonize selectively in hypoxic regions of the animal body was successfully localized and shown to proliferate in the hypoxic zone of tumor tissue, overcoming the above disadvantages. This study aimed to explore the effects of Bifidobacteria on AET (including the structure and acoustic properties of tumor tissues) and HIFU ablation at different time. The results show that the injection of Bifidobacteria increased the collagen fibre number, elastic modulus and sound velocity and decreased neovascularization in tumor tissues. The number of collagen fibres and neovascularization decreased significantly over time. Under the same HIFU irradiation intensity, the B. longum injection increased the coagulative necrosis volume and decreased the energy efficiency factor (EEF). This study confirmed that Bifidobacteria can change the AET and increase the deposition of ultrasonic energy and thereby the efficiency of HIFU. In addition, the time that Bifidobacteria stay in the tumor area after injection is an important factor. This research provides a novel approach for synergistic biologically targeted HIFU therapy.

[Effect of Bifidobacterium-induced changes in tumor tissue acoustic properties on efficacy of high-intensity focused ultrasound ablation]

OBJECTIVE

To investigate the effects of Bifidobacterium on the acoustic characteristics of tumor tissue and how such acoustic changes affect the efficacy of high-intensity focused ultrasound (HIFU) ablation in nude mice.

METHODS

Forty mice bearing human breast cancer cell (MDA-MB-231) xenograft were randomized into experimental group (n=20) and control group (n=20) for intravenous injection of Bifidobacterium suspension (200 μL, 4 × 108 cfu/mL) and PBS (200 μL) for 3 consecutive days, respectively. Before and at 3 and 7 days after the first injection, shear wave elastography was used to evaluate the hardness of the tumor tissue. On day 7 after the first injection, 10 mice from each group were sacrificed and the sound velocity and sound attenuation of the tumor tissues were measured. The changes in the collagen fibers in the tumors were evaluated using Masson staining, and neovascularization in the tumor was assessed with immunohistochemistry for platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31). The remaining 10 tumor-bearing mice in each group were subjected to HIFU ablation, and the ablation efficiency was evaluated by assessing the changes in irradiation gray values, coagulative necrosis volume, energy efficiency factor (EEF) and irradiation area and by pathological examination with HE staining.

RESULTS

In the experimental group, the collagen fibers in the tumor tissues were strong and densely aligned, and the tumors contained fewer new blood vessels showing strip-or spot-like morphologies. In the control group, the collagen fibers in the tumors were thin and loosely arranged, and the tumors showed abundant elongated or round new blood vessels. Bifidobacterium colonized in the tumor 7 days after the injection, and the tumor hardness was significantly greater in the experimental group than in the control group (P=0.01); the acoustic velocity (P=0.001) and the acoustic attenuation (P=0.000) of the tumor tissues were also greater in the experimental group. HIFU irradiation resulted in significantly greater changes in the gray scale of tumor (P=0.0006) and larger coagulative necrosis volume (P=0.0045) in the experimental group than in the control group, and the EEF was significantly smaller in the experimental group (P=0.0134).

CONCLUSIONS

Bifidobacterium can cause changes in collagen fiber content, acoustic velocity and attenuation in the tumor tissue and reduce the EEF of HIFU irradiation, thereby improving the efficacy of HIFU irradiation.

Oral engineered Bifidobacterium longum expressing rhMnSOD to suppress experimental colitis

In recent years, using genetic engineering and bioengineering techniques, Bifidobacterium as a carrier to express specific functions of the protein or polypeptide, has become a new treatment for disease. Ulcerative colitis (UC) is a type of inflammatory bowel diseases (IBD). Although the cause of this inflammatory disorder is still unknown, a large amount of evidence suggests that ulcerative colitis is associated with increased activity of reactive oxygen species (ROS), manganese superoxide dismutase (MnSOD) is a kind of superoxide dismutase (SOD) has been demonstrated to play a key role in the pathophysiology of colitis. Here, we explored the Bifidobacterium as a drug delivery system to orally deliver a potent anti-inflammatory but poor penetration and stability antioxidant enzymes human MnSOD, transported into cells by a penetratin PEP-1. We constructed an expression vector expressing PEP-1-hMnSOD fusion protein, and successfully expressed hMnSOD fusion protein in engineered Bifidobacterium. Then we identified the bioactivity of engineered Bifidobacterium in LPS-induced inflammatory cell model. Finally, we used Bifidobacterium expressing PEP-1-hMnSOD fusion protein against DSS-induced ulcerative colitis mice. B. longum-PEP-1-rhMnSOD can successfully express rhMnSOD in the colon. We found that levels of inflammatory cytokines TNF-α, IL-1β, IL-6 and IL-8 as well as histological damage in colonic tissues showed that engineered Bifidobacterium effectively reduced dextran sulfate sodium(DSS)-induced ulcerative colitis, we also tested the MPO, verified the above conclusions. These results suggest that oral Bifidobacterium expressing PEP-1-hMnSOD fusion protein can be treated as a new method of UC treatment.

Mobilome and genetic modification of bifidobacteria

Until recently, proper development of molecular studies in Bifidobacterium species has been hampered by growth difficulties, because of their exigent nutritive requirements, oxygen sensitivity and lack of efficient genetic tools. These studies, however, are critical to uncover the cross-talk between bifidobacteria and their hosts' cells and to prove unequivocally the supposed beneficial effects provided through the endogenous bifidobacterial populations or after ingestion as probiotics. The genome sequencing projects of different bifidobacterial strains have provided a wealth of genetic data that will be of much help in deciphering the molecular basis of the physiological properties of bifidobacteria. To this end, the purposeful development of stable cloning and expression vectors based on robust replicons - either from temperate phages or resident plasmids - is still needed. This review addresses the current knowledge on the mobile genetic elements of bifidobacteria (prophages, plasmids and transposons) and summarises the different types of vectors already available, together with the transformation procedures for introducing DNA into the cells. It also covers recent molecular studies performed with such vectors and incipient results on the genetic modification of these organisms, establishing the basis that would allow the use of bifidobacteria for future biotechnological applications.

Oral immunization of mice using Bifidobacterium longum expressing VP1 protein from enterovirus 71

Bifidobacterium longum is an attractive candidate for delivering biologically active proteins by the mucosal route due to its non-pathogenic and colonizing properties. Enterovirus 71 (EV71) has aroused widespread attention recently due to several epidemics, and great attention should be paid to the fact that there are currently no effective antiviral drugs or vaccines against EV71 infection. In this report, we described a recombinant B. longum that could be used to develop an oral vaccine against EV71 infection. A VP1 expression vector (pBBADs-VP1) was constructed by amplifying the EV71 VP1 gene and inserting it into the E. coli-Bifidobacterium shuttle expression vector pBBAD/Xs. Then, the expression of VP1 protein in pBBADs-VP1-transformed bacteria was demonstrated by western blot. In vivo studies indicated that oral immunization of BALB/c mice with pBBADs-VP1-transformed bacteria induced potent immune responses against EV71 infection, including virus-neutralising titers, anti-EV71-VP1 antibody and the induction of Th1 immune responses in the spleen and Peyer's patches. Importantly, immunization of mother mice with this recombinant VP1-expressing B. longum conferred protection to neonatal mice. These results demonstrate that the novel oral vaccine utilizing B. longum expressing the VP1 protein might successfully elicit a specific immune response against EV71 infection.

Susceptibility of Xenopus laevis tadpoles to infection by the ranavirus Frog-Virus 3 correlates with a reduced and delayed innate immune response in comparison with adult frogs

Xenopus laevis adults mount effective immune responses to ranavirus Frog Virus 3 (FV3) infections and clear the pathogen within 2-3 weeks. In contrast, most tadpoles cannot clear FV3 and succumb to infections within a month. While larval susceptibility has been attributed to ineffective adaptive immunity, the contribution of innate immune components has not been addressed. Accordingly, we performed a comprehensive gene expression analysis on FV3-infected tadpoles and adults. In comparison to adults, leukocytes and tissues of infected tadpoles exhibited modest (10-100 time lower than adult) and delayed (3 day later than adult) increase in expression of inflammation-associated (TNF-α, IL-1β and IFN-γ) and antiviral (Mx1) genes. In contrast, these genes were readily and robustly upregulated in tadpoles upon bacterial stimulation. Furthermore, greater proportions of larval than adult PLs were infected by FV3. Our study suggests that tadpole susceptibility to FV3 infection is partially due to poor virus-elicited innate immune responses.

Oral administration of interferon-α2b-transformed Bifidobacterium longum protects BALB/c mice against coxsackievirus B3-induced myocarditis

Multiple reports have claimed that low-dose orally administered interferon (IFN)-α is beneficial in the treatment of many infectious diseases and provides a viable alternative to high-dose intramuscular treatment. However, research is needed on how to express IFN stably in the gut. Bifidobacterium may be a suitable carrier for human gene expression and secretion in the intestinal tract for the treatment of gastrointestinal diseases. We reported previously that Bifidobacterium longum can be used as a novel oral delivery of IFN-α. IFN-transformed B. longum can exert an immunostimulatory role in mice; however the answer to whether this recombinant B. longum can be used to treat virus infection still remains elusive. Here, we investigated the efficacy of IFN-transformed B. longum administered orally on coxsackie virus B3 (CVB3)-induced myocarditis in BALB/c mice. Our data indicated that oral administration of IFN-transformed B. longum for 2 weeks after virus infection reduced significantly the severity of virus-induced myocarditis, markedly down regulated virus titers in the heart, and induced a T helper 1 cell pattern in the spleen and heart compared with controls. Oral administration of the IFN-transformed B. longum, therefore, may play a potential role in the treatment of CVB3-induced myocarditis.