Oral Bifidobacterium longum expressing GLP-2 improves nutrient assimilation and nutritional homeostasis in mice

Regulation and analysis of Simiao Yong'an Decoction fermentation by Bacillus subtilis on the diversity of intestinal microbiota in Sprague-Dawley rats

Background and Aim

Simiao Yong'an decoction (SYD) is a classic traditional Chinese medicine (TCM) prescription that has the effects of clearing heat, detoxifying, promoting blood circulation, and relieving pain. In this study, we investigated the effect of SYD on the diversity of intestinal microbiota after fermentation by Bacillus subtilis.

Materials and Methods

SYD was fermented using B. subtilis. Female Sprague-Dawley rats were randomly divided into the following four groups with six rats in each group: Negative sample group (NS), water exaction non-fermentation group (WE), B. subtilis group (BS), and fermentation liquid group (FL). All rats were orally administered for 14 days. High-throughput Illumina sequencing was used to analyze 16S rRNA expression in rat fecal samples.

Results

A total of 2782 operational taxonomical units (OTUs) were identified in this study, and 634 OTUs were shared among all samples. Bacteroidetes (28.17%-53.20%) and Firmicutes (48.35%-67.83%) were the most abundant phyla identified among the four groups. The abundance of Escherichia and Alistipes was lower in the FL group than in the NS group, whereas the abundance of Bifidobacteria and Lactobacillus was increased in the FL group (p < 0.05). The abundance of Bifidobacterium was significantly upregulated in the FL group compared with the WE and BS groups (p < 0.05).

Conclusion

After fermentation, SYD had a significantly better effect than SYD or B. subtilis. SYD significantly promoted the growth of intestinal probiotics, inhibited the growth of pathogenic bacteria, and maintained the balance of intestinal microbiota in SD rats. This study provides new insights into the development and use of SYD.

GLP-1 and GLP-2 Orchestrate Intestine Integrity, Gut Microbiota, and Immune System Crosstalk

The intestine represents the body's largest interface between internal organs and external environments except for its nutrient and fluid absorption functions. It has the ability to sense numerous endogenous and exogenous signals from both apical and basolateral surfaces and respond through endocrine and neuronal signaling to maintain metabolic homeostasis and energy expenditure. The intestine also harbours the largest population of microbes that interact with the host to maintain human health and diseases. Furthermore, the gut is known as the largest endocrine gland, secreting over 100 peptides and other molecules that act as signaling molecules to regulate human nutrition and physiology. Among these gut-derived hormones, glucagon-like peptide 1 (GLP-1) and -2 have received the most attention due to their critical role in intestinal function and food absorption as well as their application as key drug targets. In this review, we highlight the current state of the literature that has brought into light the importance of GLP-1 and GLP-2 in orchestrating intestine-microbiota-immune system crosstalk to maintain intestinal barrier integrity, inflammation, and metabolic homeostasis.

A Resource for Cloning and Expression Vectors Designed for Bifidobacteria: Overview of Available Tools and Biotechnological Applications

Bifidobacteria represent an important group of (mostly) commensal microorganisms, which have enjoyed increasing scientific and industrial attention due to their purported health-promoting attributes. For the latter reason, several species have been granted "generally recognized as safe" (GRAS) and "qualified presumption of safety" (QPS) status by the Food and Drugs Administration (FDA) and European Food Safety Authority (EFSA) organizations. Increasing scientific evidence supports their potential as oral delivery vectors to produce bioactive and therapeutic molecules at intestinal level. In order to achieve an efficient utilization of bifidobacterial strains as health-promoting (food) ingredients, it is necessary to provide evidence on the molecular mechanisms behind their purported beneficial and probiotic traits, and precise mechanisms of interaction with their human (or other mammalian) host. In this context, developing appropriate molecular tools to generate and investigate recombinant strains is necessary. While bifidobacteria have long remained recalcitrant to genetic manipulation, a wide array of Bifidobacterium-specific replicating vectors and genetic modification procedures have been described in literature. The current chapter intends to provide an updated overview on the vectors used to genetically modify and manipulate bifidobacteria, including their general characteristics, reviewing examples of their use to successfully generate recombinant bifidobacterial strains for specific purposes, and providing a general workflow and cautions to design and conduct heterologous expression in bifidobacteria. Knowledge gaps and fields of research that may help to widen the molecular toolbox to improve the functional and technological potential of bifidobacteria are also discussed.

Rhodotorula glutinis as a living cell liposome to deliver polypeptide drugs in vivo

The potential advantages of recombinant microbes as oral drug carriers for curing diseases have attracted much attention. The use of recombinant oil microbes as living cell liposomes to carry polypeptide drugs may be an ideal polypeptide oral drug delivery system. GM4-ΔTS was constructed by LFH-PCR from Rhodotorula glutinis GM4, which was screened and preserved in our laboratory, and then transferred into choline-phosphate cytidylyltransferase (CCT), which is a rate-limiting enzyme for lecithin synthesis. The results showed that the CCT gene was highly expressed in the GM4-ΔTS strain and could significantly increase fatty acid and lecithin contents in GM4-ΔTS-PGK1-CCT. Moreover, insulin, H22-LP, and α-MSH were successfully introduced into cells in vitro, and the strain no longer proliferated in vivo, for safe and controllable polypeptide drug delivery. In vivo, normal mice were intragastrically administered with recombinant strains carrying insulin and α-MSH, and different levels of polypeptide drugs were detected in serum and tissue, respectively. Then, recombinant strains carrying insulin were administered to type II diabetes mellitus mice. The results showed that the strains could effectively reduce blood glucose levels in mice, which indicated that the recombinant strains could carry insulin into the body, and the drug effect was remarkable. Therefore, recombinant GM4-ΔTS-PGK1-CCT strains were successfully used as living cell liposomes to carry insulin, H22-LP, and α-MSH peptides into the body for the first time; additionally, these strains have enhanced safety, controllability, and efficacy.

Role of glucagon-like peptides in inflammatory bowel diseases-current knowledge and future perspectives

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic, relapsing, intestinal inflammatory disorders with complex and yet unrevealed pathogenesis in which genetic, immunological, and environmental factors play a role. Nowadays, a higher proportion of elderly IBD patients with coexisting conditions, such as cardiovascular disease and/or diabetes is recorded, who require more complex treatment and became a great challenge for gastroenterologists. Furthermore, some patients do not respond to anti-IBD therapy. These facts, together with increasing comorbidities in patients with IBD, imply that urgent, more complex, novel therapeutic strategies in the treatment are needed. Glucagon-like peptides (GLPs) possess numerous functions in the human body such as lowering blood glucose level, controlling body weight, inhibiting gastric emptying, reducing food ingestion, increasing crypt cell proliferation, and improving intestinal growth and nutrient absorption. Thus, GLPs and dipeptidyl peptidase IV (DPP-IV) inhibitors have recently gained attention in IBD research. Several animal models showed that treatment with GLPs may lead to improvement of colitis. This review presents data on the multitude effects of GLPs in the inflammatory intestinal diseases and summarizes the current knowledge on GLPs, which have the potential to become a novel therapeutic option in IBD therapy.

A New Bifidobacteria Expression SysTem (BEST) to Produce and Deliver Interleukin-10 in Bifidobacterium bifidum

In the last years there has been a growing interest in the use of genetically modified bacteria to deliver molecules of therapeutic interest at mucosal surfaces. Due to the well-recognized probiotic properties of some strains, bifidobacteria represent excellent candidates for the development of live vehicles to produce and deliver heterologous proteins at mucosal surfaces. However, very few studies have considered this genus because of its complexity to be genetically manipulated. In this work, we report the development of a new Bifidobacteria Expression SysTem (BEST) allowing the production of heterologous proteins in Bifidobacterium bifidum. This system is based on: i) the broad host range plasmid pWV01, ii) a stress-inducible promoter, and iii) two different signal peptides (SPs) one issued from Lactococcus lactis (SP_Exp4) and issued from Bifidobacterium longum (SP_BL1181). The functionality of BEST system was validated by cloning murine interleukin-10 (IL-10) and establishing the resulting plasmids (i.e., pBEST_Exp4:IL-10 and pBEST_BL1181:IL-10) in the strain of B. bifidum BS42. We then demonstrated in vitro that recombinant B. bifidum BS42 harboring pBEST_BL1181:IL-10 plasmid efficiently secreted IL-10 and that this secretion was significantly higher (sevenfold) than its counterpart B. bifidum BS42 harboring pBEST_Exp4:IL-10 plasmid. Finally, we validated in vivo that recombinant B. bifidum strains producing IL-10 using BEST system efficiently delivered this cytokine at mucosal surfaces and exhibit beneficial effects in a murine model of low-grade intestinal inflammation.

The protective and anti-inflammatory effects of a modified glucagon-like peptide-2 dimer in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, recurrent, and remitting inflammatory disease resulting from immune dysregulation in the gut. As a clinically frequent disease, it can affect individuals throughout their lives, with multiple complications. Glucagon-like peptide 2 (GLP-2) is a potent epithelium-specific intestinal growth factor. However, native GLP-2 has a relatively short half-life in human circulation because of extensive renal clearance and rapid degradation by the proteolytic enzyme dipeptidyl peptidase-IV (DPP-IV). Previously, We prepared a recombinant GLP-2 variant (GLP-2②), which has increased half-life and activity as compared to the [Gly²]GLP-2 monomer. The aim of the present study was to investigate the protective potential of GLP-2② in IBD models. LPS-induced in vitro model and dextran sulfate sodium (DSS)-induced in vivo model were used to study the anti-inflammatory and therapeutic effect of GLP-2②. We found that treated with GLP-2② showed a significantly reduction in the secretion of inflammatory cytokines. Furthermore, GLP-2② alleviated symptoms of DSS-induced colitis. GLP-2② treated mice displayed an increase in body weight, lower colitis scores, and fewer mucosal damage compared with GLP-2 treated mice. MPO activities, protein expression of NLRP3 and COX2 in the colon tissues were significantly reduced in GLP-2② groups. Importantly, the ameliorative effect of GLP-2② was related to anti-apoptosis effect in colon tissues. These findings demonstrated that GLP-2② may offer a superior therapeutic benefit over [Gly²]GLP-2 monomer for treatment of IBD.