Recombinant Mouse Osteocalcin Secreted by Lactococcus lactis Promotes Glucagon-Like Peptide-1 Induction in STC-1 Cells

Development of engineered IL-36γ-hypersecreting Lactococcus lactis to improve the intestinal environment

Interleukin (IL) 36 is a member of the IL-1-like proinflammatory cytokine family that has a protective role in mucosal immunity. We hypothesized that mucosal delivery of IL-36γ to the intestine would be a very effective way to prevent intestinal diseases. Here, we genetically engineered a lactic acid bacterium, Lactococcus lactis, to produce recombinant mouse IL-36γ (rmIL-36γ). Western blotting and enzyme-linked immunosorbent assay results showed that the engineered strain (NZ-IL36γ) produced and hypersecreted the designed rmIL-36γ in the presence of nisin, which induces the expression of the recombinant gene. We administered NZ-IL36γ to mice via oral gavage, and collected the ruminal contents and rectal tissues. Colony PCR using primers specific for NZ-IL36γ, and enzyme-linked immunosorbent assay to measure the rmIL-36γ concentrations of the ruminal contents showed that NZ-IL36γ colonized the mouse intestines and secreted rmIL-36γ. A microbiota analysis revealed increased abundances of bacteria of the genera Acetatifactor, Eubacterium, Monoglobus, and Roseburia in the mouse intestines. Real-time quantitative PCR of the whole colon showed increased Muc2 expression. An in vitro assay using murine colorectal epithelial cells and human colonic cells showed that purified rmIL-36γ promoted Muc2 gene expression. Taken together, these data suggest that NZ-IL36γ may be an effective and attractive tool for delivering rmIL-36γ to improve the intestinal environment.

Development of a Single-Chain Fragment Variable that Binds to the SARS-CoV-2 Spike Protein Produced by Genetically Modified Lactic Acid Bacteria

SARS-CoV-2 enters cells via binding of the surface-exposed spike protein RBD to host cell ACE2 receptors. Therefore, in this study, we designed a scFv (single-chain fragment variable) based on the amino acid sequence of CC12.1, a neutralizing antibody found in the serum of patients with COVID-19. scFv is a low-molecular-weight antibody designed based on the antibody-antigen recognition site. Compared with the original antibody, scFv has the advantages of high tissue penetration and low production cost. In this study, we constructed gmLAB (genetically modified lactic acid bacteria) by incorporating the designed scFv into a gene expression vector and introducing it into lactic acid bacteria, aiming to develop microbial therapeutics against COVID-19. In addition, gmLAB were also constructed to produce GFP-fused scFv as a means of visualizing scFv. Expression of each scFv was confirmed by Western blotting, and the ability to bind to the RBD was investigated by ELISA. This study is the first to design a scFv against the RBD of SARS-CoV-2 using gmLAB and could be applied in the future.

Engineered probiotics introduced to improve intestinal microecology for the treatment of chronic diseases: present state and perspectives

Purpose

Correcting intestinal microecological imbalance has become one of the core strategies to treat chronic diseases. Some traditional microecology-based therapies targeting intestine, such as prebiotic therapy, probiotic therapy and fecal microbiota transplantation therapy, have been used in the prevention and treatment of clinical chronic diseases, which still facing low safety and poor controllability problems. The development of synthetic biology technology has promoted the development of intestinal microecology-based therapeutics for chronic diseases, which exhibiting higher robustness and controllability, and become an important part of the next generation of microecological therapy. The purpose of this review is to summarize the application of synthetic biology in intestinal microecology-based therapeutics for chronic diseases.

Methods

The available literatures were searched to find out experimental studies and relevant review articles on the application of synthetic biology in intestinal microecology-based therapeutics for chronic diseases from year 1990 to 2023.

Results

Evidence proposed that synthetic biology has been applied in the intestinal microecology-based therapeutics for chronic diseases, covering metabolic diseases (e.g. diabetes, obesity, nonalcoholic fatty liver disease and phenylketonuria), digestive diseases (e.g. inflammatory bowel disease and colorectal cancer), and neurodegenerative diseases (e.g. Alzheimer's disease and Parkinson's disease).

Conclusion

This review summarizes the application of synthetic biology in intestinal microecology-based therapeutics for major chronic diseases and discusses the opportunities and challenges in the above process, providing clinical possibilities of synthetic biology technology applied in microecological therapies.

Recent advances in genetic tools for engineering probiotic lactic acid bacteria

Synthetic biology has grown exponentially in the last few years, with a variety of biological applications. One of the emerging applications of synthetic biology is to exploit the link between microorganisms, biologics, and human health. To exploit this link, it is critical to select effective synthetic biology tools for use in appropriate microorganisms that would address unmet needs in human health through the development of new game-changing applications and by complementing existing technological capabilities. Lactic acid bacteria (LAB) are considered appropriate chassis organisms that can be genetically engineered for therapeutic and industrial applications. Here, we have reviewed comprehensively various synthetic biology techniques for engineering probiotic LAB strains, such as clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 mediated genome editing, homologous recombination, and recombineering. In addition, we also discussed heterologous protein expression systems used in engineering probiotic LAB. By combining computational biology with genetic engineering, there is a lot of potential to develop next-generation synthetic LAB with capabilities to address bottlenecks in industrial scale-up and complex biologics production. Recently, we started working on Lactochassis project where we aim to develop next generation synthetic LAB for biomedical application.

Development of fluorescence-labeled antibody for immune checkpoint inhibitor using engineered probiotics

Here, we developed a genetically modified lactic acid bacteria (gmLAB) that produces green fluorescent protein (GFP)-conjugating, anti-programmed death-ligand 1 (PD-L1) single-chain variable fragments (scFv) for use as an anti-cancer device that targets immune checkpoint molecules. Since PD-L1 plays a key role as an immune checkpoint molecule in the tumor microenvironment, inhibition and detection of PD-L1 are important in cancer research. The anti-PD-L1 scFv was designed based on atezolizumab, a humanized IgG1 monoclonal antibody, and integrated into a lactococcal GFP gene expression vector. Gene expression from the constructed gmLAB was confirmed by western blotting and GFP fluorescence. The ability of GFP-conjugating anti-PD-L1 scFv against the target antigen, PD-L1 protein, was shown using an enzyme-linked immunosorbent assay. Finally, the ability to recognize PD-L1-expressing tumor-cell lines was confirmed using flow cytometry and fluorescence microscopy. Our results suggest that the gmLAB could be applied to in vivo imaging in cancer as an affordable diagnostic/treatment tool.

Osteocalcin and the Physiology of Danger

Bone biology has long been driven by the question as to what molecules affect cell differentiation or the functions of bone. Exploring this issue has been an extraordinarily powerful way to improve our knowledge of bone development and physiology. More recently, a second question has emerged: does bone have other functions besides making bone? Addressing this conundrum revealed that the bone-derived hormone osteocalcin affects a surprisingly large number of organs and physiological processes, including acute stress response. This review will focus on this emerging aspect of bone biology taking osteocalcin as a case study and will show how classical and endocrine functions of bone help to define a new functional identity for this tissue.

A Soybean Resistant Protein-Containing Diet Increased the Production of Reg3γ Through the Regulation of the Gut Microbiota and Enhanced the Intestinal Barrier Function in Mice

The maintenance of intestinal homeostasis is necessary for a good quality of life, and strengthening of the intestinal barrier function is thus an important issue. Therefore, we focused on soybean resistant protein (SRP) derived from kori-tofu (freeze-dried tofu), which is a traditional Japanese food, as a functional food component. In this study, to investigate the effect of SRP on the intestinal barrier function and intestinal microbiota, we conducted an SRP free intake experiment in mice. Results showed that ingestion of SRP decreased the serum level of lipopolysaccharide-binding protein and induced the expression of Reg3γ, thereby improving the intestinal barrier function. In addition, SRP intake induced changes in the cecal microbiota, as observed by changes in β-diversity. In particular, in the microbiota, the up-regulation of functional gene pathways related to the bacterial invasion of epithelial cells (ko05100) was observed, suggesting that Reg3γ expression was induced by the direct stimulation of epithelial cells. The results of this study suggest that SRP is a functional food component that may contribute to the maintenance of intestinal homeostasis.

Explaining Divergent Observations Regarding Osteocalcin/GPRC6A Endocrine Signaling

A new schema proposes that the bone-derived osteocalcin (Ocn) peptide hormone activates the G-protein-coupled receptor GPRC6A to directly regulate glucose and fat metabolism in liver, muscle, and fat, and to stimulate the release of metabolism-regulating hormones, including insulin, fibroblast growth factor 21, glucagon-like peptide 1, testosterone, and interleukin 6. Ocn/GPRC6A activation has also been implicated in cancer progression. GPRC6A is activated by cations, amino acids, and testosterone. The multiligand specificity, the regulation of energy metabolism in diverse tissues, and the coordinated release of metabolically active hormones make the GPRC6A endocrine networks unique. Recently, the significance of Ocn/GPRCA has been questioned. There is a lack of metabolic abnormalities in newly created genetically engineered Ocn- and Gprc6a-deficient mouse models. There are also paradoxical observations that GPRC6A may function as a tumor suppressor. In addition, discordant published studies have cast doubt on the function of the most prevalent uniquely human GPRC6A-KGKY polymorphism. Explanations for these divergent findings are elusive. We provide evidence that the metabolic susceptibility of genetically engineered Ocn- and Gprc6a-deficient mice is influenced by environmental challenges and genetic differences in mouse strains. In addition, the GPRC6A-KGKY polymorphism appears to be a gain-of-function variant. Finally, alternatively spliced isoforms of GPRC6A may alter ligand specificity and signaling that modulate oncogenic effects. Thus, genetic, post-translational and environmental factors likely account for the variable results regarding the functions of GPRC6A in animal models. Pending additional information, GPRC6A should remain a potential therapeutic target for regulating energy and fat metabolism, hormone production, and cancer progression.

Construction of Genetically Modified Lactococcus lactis Producing Anti-human-CTLA-4 Single-Chain Fragment Variable

Lactic acid bacteria are human commensal organisms that have immunomodulatory and metabolism-promoting effects. In addition, due to the increasing demand for biopharmaceuticals, genetically modified lactic acid bacteria (gmLAB) that produce recombinant proteins are expected to be used as microbial therapeutics and next-generation probiotics. In this study, we constructed a gmLAB strain that produces anti-human cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) single-chain fragment variable (CTLA4scFv) for possible use in a cancer treatment strategy using gmLAB. CTLA-4, an immune checkpoint molecule, suppresses the anti-cancer immune response; thus, inhibition of CTLA-4 signaling is important in cancer therapy. In this study, we designed a CTLA4scFv composed of a heavy and light chain of the variable region from anti-human CTLA-4 antibody connected by a flexible peptide linker. CTLA4scFv was expressed using nisin controlled gene expression (NICE) system, a lactococcal inducible gene expression system, and the DNA sequence encoding CTLA4scFv was inserted downstream of the P_nisA promoter of the gene expression vector pNZ8148#2. Furthermore, expression of recombinant CTLA4scFv was confirmed by Western blotting, and the immunoreactivity of recombinant CTLA4scFv against human CTLA-4 protein was examined using ELISA. We speculate that gmLAB producing bioactive CTLA4scFv will become an attractive approach for cancer treatment.

Construction of genetically modified Lactococcus lactis that produces bioactive anti-interleukin-4 single-chain fragment variable

Interleukin 4 (IL-4) is a cytokine that induces T-cell differentiation and the production of antibodies from B cells, and plays a crucial role in the allergic response. Therefore, development of a therapeutic approach against IL-4 signaling is expected to prevent or control Th2-related allergic diseases. IL-4 single-chain fragment variable (scFv), which is a recombinant protein consisting of the Fv region of an IL-4 antibody connected to a flexible peptide linker, is expected to be an inhibitor of IL-4 signaling. In this study, recombinant IL-4 scFv was produced by genetically modified lactic acid bacteria (gmLAB); this system is gaining attention as a type of microbial therapeutics. Recombinant gene expression was confirmed with western blotting, and the IL-4 recognition ability of IL-4 scFv produced by gmLAB was examined with an enzyme-linked immunosorbent assay. The macrophage cell line, Raw264.7, and peritoneal macrophages isolated from C57BL/6 mice were employed for an in vitro IL-4 signaling inhibition assay. IL-4 stimulation increased the mRNA expression of arginase-1, a biomarker of IL-4 signaling in macrophages, but arginase-1 expression was suppressed by IL-4 scFv produced by gmLAB, indicating that IL-4 scFv has IL-4 signaling inhibitory activity. gmLAB that produces bioactive IL-4 scFv that was constructed in this study could be an attractive approach for treating allergic disorders.

Recombinant mouse calcitonin gene-related peptide secreted by Lactococcus lactis inhibits lipopolysaccharide-induced inflammatory response in macrophages

We describe the development of a genetically modified strain of lactic acid bacteria (gmLAB) capable of producing a recombinant mouse calcitonin gene-related peptide (rCGRP). This strain (NZ-CGRP) was generated by introducing a CGRP secretion plasmid into Lactococcus lactis NZ9000. Western blotting confirmed the secretion of rCGRP in the presence of the inducer nisin. Highly purified rCGRP was obtained from the culture supernatants of NZ-CGRP. We demonstrated that prophylactic exposure of a culture of mouse peritoneal macrophages to rCGRP inhibited lipopolysaccharide (LPS) induction of tumor necrosis factor-α (TNF-α). The rCGRP-secreting gmLAB strain holds promise for development as a new anti-inflammatory prophylactic.