Prevention and treatment of colitis with Lactococcus lactis secreting the immunomodulatory Yersinia LcrV protein

Bioinspired and biomimetic strategies for inflammatory bowel disease therapy

Inflammatory bowel disease (IBD) is an idiopathic chronic inflammatory bowel disease with high morbidity and an increased risk of cancer or death, resulting in a heavy societal medical burden. While current treatment modalities have been successful in achieving long-term remission and reducing the risk of complications, IBD remains incurable. Nanomedicine has the potential to address the high toxic side effects and low efficacy in IBD treatment. However, synthesized nanomedicines typically exhibit some degree of immune rejection, off-target effects, and a poor ability to cross biological barriers, limiting the development of clinical applications. The emergence of bionic materials and bionic technologies has reshaped the landscape in novel pharmaceutical fields. Biomimetic drug-delivery systems can effectively improve biocompatibility and reduce immunogenicity. Some bioinspired strategies can mimic specific components, targets or immune mechanisms in pathological processes to produce targeting effects for precise disease control. This article highlights recent research on bioinspired and biomimetic strategies for the treatment of IBD and discusses the challenges and future directions in the field to advance the treatment of IBD.

Advancement of Engineered Bacteria for Orally Delivered Therapeutics

The use of bacteria and their biotic components as therapeutics has shown great potential in the treatment of diseases. Orally delivered bacteria improve patient compliance compared with injection-administered bacteria and are considered the preferred mode. However, due to the harsh gastrointestinal environment, the viability and therapeutic efficacy of orally delivered bacteria are significantly reduced in vivo. In recent years, with the rapid development of synthetic biology and nanotechnology, bacteria and biotic components have been engineered to achieve directed genetic reprogramming for construction and precise spatiotemporal control in the gastrointestinal tract, which can improve viability and therapeutic efficiency. Herein, a state-of-the-art review on the current progress of engineered bacterial systems for oral delivery is provided. The different types of bacterial and biotic components for oral administration are first summarized. The engineering strategies of these bacteria and biotic components and their treatment of diseases are next systematically summarized. Finally, the current challenges and prospects of these bacterial therapeutics are highlighted that will contribute to the development of next-generation orally delivered bacteriotherapy.

The Role of Genetically Engineered Probiotics for Treatment of Inflammatory Bowel Disease: A Systematic Review

BACKGROUND

Many preclinical studies have demonstrated the effectiveness of genetically modified probiotics (gm probiotics) in animal models of inflammatory bowel disease (IBD).

OBJECTIVE

This systematic review was performed to investigate the role of gm probiotics in treating IBD and to clarify the involved mechanisms.

METHODS

PubMed, Web of Science, Cochrane Library, and Medline were searched from their inception to 18 September 2022 to identify preclinical and clinical studies exploring the efficacy of gm probiotics in IBD animal models or IBD patients. Two independent researchers extracted data from the included studies, and the data were pooled by the type of study; that is, preclinical or clinical.

RESULTS

Forty-five preclinical studies were included. In these studies, sodium dextran sulfate and trinitrobenzene sulfonic acid were used to induce colitis. Eleven probiotic species have been genetically modified to produce therapeutic substances, including IL-10, antimicrobial peptides, antioxidant enzymes, and short-chain fatty acids, with potential therapeutic properties against colitis. The results showed generally positive effects of gm probiotics in reducing disease activity and ameliorating intestinal damage in IBD models; however, the efficacy of gm probiotics compared to that of wild-type probiotics in many studies was unclear. The main mechanisms identified include modulation of the diversity and composition of the gut microbiota, production of regulatory metabolites by beneficial bacteria, reduction of the pro- to anti-inflammatory cytokine ratio in colonic tissue and plasma, modulation of oxidative stress activity in the colon, and improvement of intestinal barrier integrity. Moreover, only one clinical trial with 10 patients with Crohn's disease was included, which showed that L. lactis producing IL-10 was safe, and a decrease in disease activity was observed in these patients.

CONCLUSIONS

Gm probiotics have a certain efficacy in colitis models through several mechanisms. However, given the scarcity of clinical trials, it is important for researchers to pay more attention to gm probiotics that are more effective and safer than wild-type probiotics to facilitate further clinical translation.

About Functional Foods: The Probiotics and Prebiotics State of Art

Poor diet, obesity and a sedentary lifestyle have a significant impact on natural microbiota disorders; specifically, the intestinal one. This in turn can lead to a multitude of organ dysfunctions. The gut microbiota contains more than 500 species of bacteria and constitutes 95% of the total number of cells in the human body, thus contributing significantly to the host's resistance to infectious diseases. Nowadays, consumers have turned to purchased foods, especially those containing probiotic bacteria or prebiotics, that constitute some of the functional food market, which is constantly expanding. Indeed, there are many products available that incorporate probiotics, such as yogurt, cheese, juices, jams, cookies, salami sausages, mayonnaise, nutritional supplements, etc. The probiotics are microorganisms that, when taken in sufficient amounts, contribute positively to the health of the host and are the focus of interest for both scientific studies and commercial companies. Thus, in the last decade, the introduction of DNA sequencing technologies with subsequent bioinformatics processing contributes to the in-depth characterization of the vast biodiversity of the gut microbiota, their composition, their connection with the physiological function-known as homeostasis-of the human organism, and their involvement in several diseases. Therefore, in this study, we highlighted the extensive investigation of current scientific research for the association of those types of functional foods containing probiotics and prebiotics in the diet and the composition of the intestinal microbiota. As a result, this study can form the foundation for a new research path based on reliable data from the literature, acting a guide in the continuous effort to monitor the rapid developments in this field.

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.

Novel technologies to characterize and engineer the microbiome in inflammatory bowel disease

We present an overview of recent experimental and computational advances in technology used to characterize the microbiome, with a focus on how these developments improve our understanding of inflammatory bowel disease (IBD). Specifically, we present studies that make use of flow cytometry and metabolomics assays to provide a functional characterization of microbial communities. We also describe computational methods for strain-level resolution, temporal series, mycobiome and virome data, co-occurrence networks, and compositional data analysis. In addition, we review novel techniques to therapeutically manipulate the microbiome in IBD. We discuss the benefits and drawbacks of these technologies to increase awareness of specific biases, and to facilitate a more rigorous interpretation of results and their potential clinical application. Finally, we present future lines of research to better characterize the relation between microbial communities and IBD pathogenesis and progression.

Foundations of gastrointestinal-based drug delivery and future developments

Gastrointestinal-based drug delivery is considered the preferred mode of drug administration owing to its convenience for patients, which improves adherence. However, unique characteristics of the gastrointestinal tract (such as the digestive environment and constraints on transport across the gastrointestinal mucosa) limit the absorption of drugs. As a result, many medications, in particular biologics, still exist only or predominantly in injectable form. In this Review, we examine the fundamentals of gastrointestinal drug delivery to inform clinicians and pharmaceutical scientists. We discuss general principles, including the challenges that need to be overcome for successful drug formulation, and describe the unique features to consider for each gastrointestinal compartment when designing drug formulations for topical and systemic applications. We then discuss emerging technologies that seek to address remaining obstacles to successful gastrointestinal-based drug delivery.

Living Therapeutics: The Next Frontier of Precision Medicine

Modern medicine has long studied the mechanism and impact of pathogenic microbes on human hosts, but has only recently shifted attention toward the complex and vital roles that commensal and probiotic microbes play in both health and dysbiosis. Fueled by an enhanced appreciation of the human-microbe holobiont, the past decade has yielded countless insights and established many new avenues of investigation in this area. In this review, we discuss advances, limitations, and emerging frontiers for microbes as agents of health maintenance, disease prevention, and cure. We highlight the flexibility of microbial therapeutics across disease states, with special consideration for the rational engineering of microbes toward precision medicine outcomes. As the field advances, we anticipate that tools of synthetic biology will be increasingly employed to engineer functional living therapeutics with the potential to address longstanding limitations of traditional drugs.

Site-specific targeted drug delivery systems for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn's disease and ulcerative colitis and manifests as a complex and dysregulated immune response. To date, there is no cure for IBD; thus, lifelong administration of maintenance drugs is often necessary. Since conventional IBD treatment strategies do not target the sites of inflammation, only limited efficacy is observed with their use. Moreover, the possibility of severe side effects resulting from systemic drug redistribution is high when conventional drug treatments are used. Therefore, a straightforward disease-targeted drug delivery system is desirable. Based on the pathophysiological changes associated with IBD, novel site-specific targeted drug delivery strategies that deliver drugs directly to the inflammation sites can enhance drug accumulation and decrease side effects. This review summarizes novel inflammation targeted delivery systems in the management of IBD. It also discusses the challenges and new perspectives in this field.

Effects of recombinant Lactobacillus casei on growth performance, immune response and disease resistance in crucian carp, Carassius auratus

In the present study, we constructed two recombinant Lactobacillus casei (L. casei) Lc-pPG-1-AcrV (surface-displayed) and Lc-pPG-2-AcrV (secretory) constitutively expressing AcrV protein of Aeromonas veronii (A. veronii). Expression of recombinant AcrV protein was verified by western blot and immunofluorescence technique. Compared with PBS group, the final weight (FW), weight gain (WG) and specific growth rate (SGR) of fish fed Lc-pPG-1-AcrV, Lc-pPG-2-AcrV and Lc-pPG diets after 56 days observed significantly increase (p < 0.05), while the feed conversion ratio (FCR) showed a significantly decrease (p < 0.05). The recombinant L. casei strains were orally administrated to crucian carp, and significant increased (p < 0.05) the immunoglobulin M (IgM), elevated the acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM) and superoxide dismutase (SOD) activity in serum. Moreover, leukocytes phagocytosis percentage and index of the recombinant L. casei were both enhanced. The results demonstrated that the recombinant L. casei could elicit systemic immune responses and increase the serum immunological index. The Interleukin-10 (IL-10), Interleukin-1β (IL-1β), interferon-γ (IFN-γ) and Tumor Necrosis Factor-α (TNF-α) levels in liver, spleen, kidney and intestine have up regulated significantly in tissues (p < 0.05), suggesting that the recombinant L. casei has the ability to induce expression of cytokines and enhance the innate immune response. Higher survival rates were exhibited that crucian carp immunized with Lc-pPG-1-AcrV (67.5%) and Lc-pPG-2-AcrV (52.5%) after challenge with A. veronii. In conclusion, these two recombinant L. casei vaccine were effective in improving crucian carp growth, immunity response and disease resistance. The recombinant L. casei strains may be a promising candidate for the development of an oral vaccine against A. veronii.

Oral Delivery of Biologics for Precision Medicine

The emerging field of precision medicine is rapidly growing, fostered by the advances in genome mapping and molecular diagnosis. In general, the translation of these advances into precision treatments relies on the use of biological macromolecules, whose structure offers a high specificity and potency. Unfortunately, due to their complex structure and limited ability to overcome biological barriers, these macromolecules need to be administered via injection. The scientific community has devoted significant effort to making the oral administration of macromolecules plausible thanks to the implementation of drug delivery technologies. Here, an overview of the current situation and future prospects in the field of oral delivery of biologics is provided. Technologies in clinical trials, as well as recent and disruptive delivery systems proposed in the literature for local and systemic delivery of biologics including peptides, antibodies, and nucleic acids, are described. Strategies for the specific targeting of gastrointestinal regions-stomach, small bowel, and colon-cell populations, and internalization pathways, are analyzed. Finally, challenges associated with the clinical translation, future prospects, and identified opportunities for advancement in this field are also discussed.

Nanoparticle-Mediated Drug Delivery Systems For The Treatment Of IBD: Current Perspectives

Inflammatory bowel disease (IBD), which mainly consists of Crohn’s disease and ulcerative colitis, is a chronic and relapsing inflammatory condition of the gastrointestinal tract. The traditional treatment strategies relied on frequent administration of high dosages of medications, including antibiotics, non-steroidal anti-inflammatory drugs, biologics, and immunomodulators, with the goal of reducing inflammation. Some of these medications were effective in alleviating the early-stage inflammatory symptoms, but their long-term efficacies were compromised by the accumulation of toxicities. Recently, nanoparticle (NP)-based drugs have been widely studied for their potential to solve such problems. Various mechanisms/strategies, including size-, charge-, pH-, pressure-, degradation-, ligand-receptor-, and microbiome- dependent drug delivery systems, have been exploited in preclinical studies. A certain number of NP delivery systems have sought to target drugs to the inflamed intestine. Although several NP-based drugs have entered clinical trials for the treatment of IBD, most have failed due to premature drug release, weak targeting ability, and the high immune toxicity of some of the synthetic nanomaterials that have been used to fabricate the NPs. Therefore, there is still a need for rationally designed and stable NP drug delivery system that can specifically target drugs to the disease site, prolong the drug’s residence time, and minimize systemic side effects. This review will analyze the current state of the art in NP-mediated drug delivery for IBD treatment. We will focus on topics such as deliverable targets (at the tissue or cellular level) for treating inflammation; the target-homing NP materials that can interact with such targets; and the major administration routes for treating IBD. These discussions will integrate notable trends in the research and development of IBD medications, including multi-responsive NP-mediated delivery and naturally-derived targeting NPs. Finally, current challenges and future directions will be presented in the hopes of advancing the study of NP-mediated strategies for treating IBD.

Oral delivery of pancreatitis-associated protein by Lactococcus lactis displays protective effects in dinitro-benzenesulfonic-acid-induced colitis model and is able to modulate the composition of the microbiota

Antimicrobial peptides secreted by intestinal immune and epithelial cells are important effectors of innate immunity. They play an essential role in the maintenance of intestinal homeostasis by limiting microbial epithelium interactions and preventing unnecessary microbe‐driven inflammation. Pancreatitis‐associated protein (PAP) belongs to Regenerating islet‐derived III proteins family and is a C‐type (Ca⁺² dependent) lectin. PAP protein plays a protective effect presenting anti‐inflammatory properties able to reduce the severity of colitis, preserving gut barrier and epithelial inflammation. Here, we sought to determine whether PAP delivered at intestinal lumen by recombinant Lactococcus lactis strain (LL‐PAP) before and after chemically induced colitis is able to reduce the severity in two models of colitis. After construction and characterization of our recombinant strains, we tested their effects in dinitro‐benzenesulfonic‐acid (DNBS) and Dextran sulfate sodium (DSS) colitis model. After the DNBS challenge, mice treated with LL‐PAP presented less severe colitis compared with PBS and LL‐empty‐treated mice groups. After the DSS challenge, no protective effects of LL‐PAP could be detected. We determined that after 5 days administration, LL‐PAP increase butyrate producer's bacteria, especially Eubacterium plexicaudatum. Based on our findings, we hypothesize that a treatment with LL‐PAP shifts the microbiota preventing the severity of colon inflammation in DNBS colitis model. These protective roles of LL‐PAP in DNBS colitis model might be through intestinal microbiota modulation.

Bacillus megaterium SF185 spores exert protective effects against oxidative stress in vivo and in vitro

Endogenous reactive oxygen species (ROS) are by-products of the aerobic metabolism of cells and have an important signalling role as secondary messengers in various physiological processes, including cell growth and development. However, the excessive production of ROS, as well as the exposure to exogenous ROS, can cause protein oxidation, lipid peroxidation and DNA damages leading to cell injuries. ROS accumulation has been associated to the development of health disorders such as neurodegenerative and cardiovascular diseases, inflammatory bowel disease and cancer. We report that spores of strain SF185, a human isolate of Bacillus megaterium, have antioxidant activity on Caco-2 cells exposed to hydrogen peroxide and on a murine model of dextran sodium sulfate-induced oxidative stress. In both model systems spores exert a protective state due to their scavenging action: on cells, spores reduce the amount of intracellular ROS, while in vivo the pre-treatment with spores protects mice from the chemically-induced damages. Overall, our results suggest that treatment with SF185 spores prevents or reduces the damages caused by oxidative stress. The human origin of SF185, its strong antioxidant activity, and its protective effects led to propose the spore of this strain as a new probiotic for gut health.

Recent trends and advances in microbe-based drug delivery systems

Since more than a decade, pharmaceutical researchers endeavor to develop an effective, safe and target-specific drug delivery system to potentiate the therapeutic actions and reduce the side effects. The conventional drug delivery systems (DDSs) show the improvement in the lifestyle of the patients suffering from non-communicable diseases, autoimmune diseases but sometimes, drug resistance developed during the treatment is a major concern for clinicians to find an alternative and more advanced transport systems. Advancements in drug delivery facilitate the development of active carrier for targeted action with improved pharmacokinetic behavior. This review article focuses on microbe-based drug delivery systems to provide safe, non-toxic, site-specific targeted action with lesser side effects. Pharmaceutical researchers play a vital part in microbe-based drug delivery systems as a therapeutic agent and carrier. The properties of microorganisms like self-propulsion, in-situ production of therapeutics, penetration into the tumor cells, increase in immunity, etc. are of interest for development of highly effective delivery carrier. Lactococcus lactis is therapeutically helpful in Inflammatory Bowel Disease (IBD) and is under investigation of phase I clinical trial. Moreover, bacteria, anti-cancer oncolytic viruses, viral vectors (gene therapy) and viral immunotherapy are the attractive areas of biotechnological research. Virus acts as a distinctive candidate for imaging of tumor and accumulation of active in tumor. Graphical abstract Classification of microbe-based drug delivery system.

Contribution of the Gut Microbiota in P28GST-Mediated Anti-Inflammatory Effects: Experimental and Clinical Insights

An original immuno-regulatory strategy against inflammatory bowel diseases based on the use of 28 kDa glutathione S-transferase (P28GST), a unique schistosome protein, was recently proposed. Improvement of intestinal inflammation occurs through restoration of the immunological balance between pro-inflammatory T-helper 1 (Th1) responses and both T-helper 2 (Th2) and regulatory responses. However, detailed mechanisms explaining how P28GST prevents colitis and promotes gut homeostasis remain unknown. Considering the complex interplay between the adaptive and innate immune system and the intestinal microbiota, we raised the question of the possible role of the microbial ecosystem in the anti-inflammatory effects mediated by the helminth-derived P28GST protein. We first analyzed, by 16S rRNA sequencing, the bacterial profiles of mice fecal microbiota at several time points of the P28GST-immunomodulation period prior to trinitrobenzene sulfonic acid (TNBS)-colitis. The influence of gut microbiota in the P28GST-mediated anti-inflammatory effects was then assessed by fecal microbiota transplantation experiments from P28GST-immunized mice to either conventional or microbiota depleted naïve recipient mice. Finally, the experimental data were supplemented by the temporal fecal microbiota compositions of P28GST-treated Crohn’s disease patients from a pilot clinical study (NCT02281916). The P28GST administration slightly modulated the diversity and composition of mouse fecal microbiota while it significantly reduced experimental colitis in mice. Fecal microbiota transplantation experiments failed to restore the P28GST-induced anti-inflammatory effects. In Crohn’s disease patients, P28GST also induced slight changes in their overall fecal bacterial composition. Collectively, these results provide key elements in both the anti-inflammatory mechanisms and the safe therapeutic use of immunomodulation with such promising helminth-derived molecules.

Microbial modulation of the gut microbiome for treating autoimmune diseases

Many studies have shown the relationship between autoimmune diseases and the gut microbiome in humans: those with autoimmune conditions display gut microbiome dysbiosis. The big question that needs to be addressed is if restoring eubiosis of the gut microbiota can help suppress the autoimmune condition by activating various immune regulatory mechanisms. Inducing these self-healing mechanisms should prolong good health in affected individuals. Area covered: Here, we review the available clinical and preclinical studies that have used selective bacteria for modulating gut microbiota for treating autoimmune diseases. The potential bacterial candidates and their mechanism of action in treating autoimmune diseases will be discussed. We searched for genetically modified and potential probiotics for diseases and discuss the most likely candidates. Expert commentary: To achieve eubiosis, manipulation of the gut microbiota must occur in some form. Several approaches for modulating gut microbiota include prebiotic diets, antimicrobial interventions, fecal microbiota transplants, and selective probiotics. One novel approach showing promising results is the use of selective bacterial candidates to modulate microbial composition. Use of single microbe for treatment has an advantage as compared to multi-species as microbes grow at different rates and if needed, a single microbe is easy to target.

Genetic Engineering of Lactococcus lactis Co-producing Antigen and the Mucosal Adjuvant 3' 5'- cyclic di Adenosine Monophosphate (c-di-AMP) as a Design Strategy to Develop a Mucosal Vaccine Prototype

Lactococcus lactis is a promising candidate for the development of mucosal vaccines. More than 20 years of experimental research supports this immunization approach. In addition, 3′ 5′- cyclic di-adenosine monophosphate (c-di-AMP) is a bacterial second messenger that plays a key role in the regulation of diverse physiological functions (potassium and cellular wall homeostasis, among others). Moreover, recent studies showed that c-di-AMP has a strong mucosal adjuvant activity that promotes both humoral and cellular immune responses. In this study, we report the development of a novel mucosal vaccine prototype based on a genetically engineered L. lactis strain. First, we demonstrate that homologous expression of cdaA gen in L. lactis is able to increase c-di-AMP levels. Thus, we hypothesized that in vivo synthesis of the adjuvant can be combined with production of an antigen of interest in a separate form or jointly in the same strain. Therefore, a specifically designed fragment of the trans-sialidase (TScf) enzyme from the Trypanosoma cruzi parasite, the etiological agent of Chagas disease, was selected to evaluate as proof of concept the immune response triggered by our vaccine prototypes. Consequently, we found that oral administration of a L. lactis strain expressing antigenic TScf combined with another L. lactis strain producing the adjuvant c-di-AMP could elicit a TS-specific immune response. Also, an additional L. lactis strain containing a single plasmid with both cdaA and tscf genes under the Pcit and Pnis promoters, respectively, was also able to elicit a specific immune response. Thus, the current report is the first one to describe an engineered L. lactis strain that simultaneously synthesizes the adjuvant c-di-AMP as well as a heterologous antigen in order to develop a simple and economical system for the formulation of vaccine prototypes using a food grade lactic acid bacterium.

Engineering Diagnostic and Therapeutic Gut Bacteria

Genetically engineered bacteria have the potential to diagnose and treat a wide range of diseases linked to the gastrointestinal tract, or gut. Such engineered microbes will be less expensive and invasive than current diagnostics and more effective and safe than current therapeutics. Recent advances in synthetic biology have dramatically improved the reliability with which bacteria can be engineered with the sensors, genetic circuits, and output (actuator) genes necessary for diagnostic and therapeutic functions. However, to deploy such bacteria in vivo, researchers must identify appropriate gut-adapted strains and consider performance metrics such as sensor detection thresholds, circuit computation speed, growth rate effects, and the evolutionary stability of engineered genetic systems. Other recent reviews have focused on engineering bacteria to target cancer or genetically modifying the endogenous gut microbiota in situ. Here, we develop a standard approach for engineering "smart probiotics," which both diagnose and treat disease, as well as "diagnostic gut bacteria" and "drug factory probiotics," which perform only the former and latter function, respectively. We focus on the use of cutting-edge synthetic biology tools, gut-specific design considerations, and current and future engineering challenges.

Using murine colitis models to analyze probiotics-host interactions

Probiotics are defined as 'live microorganisms which when administered in adequate amounts confer a health benefit on the host'. So, to consider a microorganism as a probiotic, a demonstrable beneficial effect on the health host should be shown as well as an adequate defined safety status and the capacity to survive transit through the gastrointestinal tract and to storage conditions. In this review, we present an overview of the murine colitis models currently employed to test the beneficial effect of the probiotic strains as well as an overview of the probiotics already tested. Our aim is to highlight both the importance of the adequate selection of the animal model to test the potential probiotic strains and of the value of the knowledge generated by these in vivo tests.

Lactococcus lactis As a Versatile Vehicle for Tolerogenic Immunotherapy

Genetically modified Lactococcus lactis bacteria have been engineered as a tool to deliver bioactive proteins to mucosal tissues as a means to exert both local and systemic effects. They have an excellent safety profile, the result of years of human consumption in the food industry, as well as a lack of toxicity and immunogenicity. Also, containment strategies have been developed to promote further application as clinical protein-based therapeutics. Here, we review technological advancements made to enhanced the potential of L. lactis as live biofactories and discuss some examples of tolerogenic immunotherapies mediated by mucosal drug delivery via L. lactis. Additionally, we highlight their use to induce mucosal tolerance by targeted autoantigen delivery to the intestine as an approach to reverse autoimmune type 1 diabetes.

Nanoparticulate Drug Delivery Systems Targeting Inflammation for Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, idiopathic inflammatory set of conditions that can affect the entire gastrointestinal (GI) tract and is associated with an increased risk of colorectal cancer. To date there is no curative therapy for IBD; therefore life-long medication can be necessary for IBD management if surgery is to be avoided. Drug delivery systems specific to the colon have improved IBD treatment and several such systems are available to patients. However, current delivery systems for IBD do not target drugs to the site of inflammation, which leads to frequent dosing and potentially severe side effects that can adversely impact patients' adherence to medication. There is a need for novel drug delivery systems that can target drugs to the site of inflammation, prolong local drug availability, improve therapeutic efficacy, and reduce drug side effects. Nanoparticulate (NP) systems are attractive in designing targeted drug delivery systems for the treatment of IBD because of their unique physicochemical properties and capability of targeting the site of disease. This review analyzes the microenvironment at the site of inflammation in IBD, highlighting the pathophysiological features as possible cues for targeted delivery; discusses different strategies and mechanisms of NP targeting IBD, including size-, charge-, ligand-receptor, degradation- and microbiome-mediated approaches; and summarizes recent progress on using NPs towards improved therapies for IBD. Finally, challenges and future directions in this field are presented to advance the development of targeted drug delivery for IBD treatment.

Hsp65-Producing Lactococcus lactis Prevents Inflammatory Intestinal Disease in Mice by IL-10- and TLR2-Dependent Pathways

Heat shock proteins (Hsps) are highly expressed at all sites of inflammation. As they are ubiquitous and immunodominant antigens, these molecules represent good candidates for the therapeutic use of oral tolerance in autoimmune and chronic inflammatory diseases. Evidences from human and animal studies indicate that inflammatory bowel disease (IBD) results from uncontrolled inflammatory responses to intestinal microbiota. Hsps are immunodominant proteins expressed by several immune cells and by commensal bacteria. Using an IBD mouse model, we showed that oral pretreatment with genetically modified Lactococcus lactis that produces and releases Mycobacterium Hsp65, completely prevented DSS-induced colitis in C57BL/6 mice. Protection was associated with reduced pro-inflammatory cytokines, such as IFN-γ, IL-6, and TNF-α; increased IL-10 production in colonic tissue; and expansion of CD4⁺Foxp3⁺ and CD4⁺LAP⁺ regulatory T cells in spleen and mesenteric lymph nodes. This effect was dependent on IL-10 and toll-like receptor 2. Thus, this approach may open alternative options for long-term management of IBD.

Applications of Genetically Modified Immunobiotics with High Immunoregulatory Capacity for Treatment of Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs), including ulcerative colitis and Crohn’s disease, are chronic inflammatory diseases characterized by dysregulated immune responses of the gastrointestinal tract. In recent years, the incidence of IBDs has increased in developed nations, but their prophylaxis/treatment is not yet established. Site-directed delivery of molecules showing anti-inflammatory properties using genetically modified (gm)-probiotics shows promise as a new strategy for the prevention and treatment of IBD. Advantages of gm-probiotics include (1) the ability to use bacteria as a delivery vehicle, enabling safe and long-term use by humans, (2) decreased risks of side effects, and (3) reduced costs. The intestinal delivery of anti-inflammatory proteins such as cytokines and enzymes using Lactococcus lactis has been shown to regulate host intestinal homeostasis depending on the delivered protein-specific machinery. Additionally, clinical experience using interleukin 10-secreting Lc. lactis has been shown to be safe and to facilitate biological containment in IBD therapy. On the other hand, some preclinical studies have demonstrated that gm-strains of immunobiotics (probiotic strains able to beneficially regulate the mucosal immunity) provide beneficial effects on intestinal inflammation as a result of the synergy between the immunoregulatory effects of the bacterium itself and the anti-inflammatory effects of the delivered recombinant proteins. In this review, we discuss the rapid progression in the development of strategies for the prophylaxis and treatment of IBD using gm-probiotics that exhibit immune regulation effects (gm-immunobiotics). In particular, we discuss the type of strains used as delivery agents.

Bioengineered Colorectal Cancer Drugs: Orally Delivered Anti-Inflammatory Agents

Intestinal inflammation is one of the major factors that increase colorectal cancer (CRC) incidence worldwide. Inflammation in the gastrointestinal tract is directly linked to tumor development at the early stages of the disease, thus a key issue toward the prevention and the treatment of colonic neoplasia. Thus, the use of anti-inflammatory drugs has emerged first as a strategy to reduce chronic inflammation in case of many inflammatory bowel diseases (IBD), but it has proven its efficacy by reducing the risk of colonic neoplasia. This comprehensive review highlights the role of chronic inflammation, mainly in IBD, in the development of CRC including molecular and immune mechanisms that have tumorigenic effects. Multiple lines of evidence indicate that several bioactive and phytochemical compounds used as anti-inflammatory drugs have also antitumoral attributes. The uses of orally delivered cytokines and small molecules, as well as key dietary supplementation as anti-inflammatory therapeutics are discussed. In addition, comprehensive knowledge about CRC and intestinal inflammation, and the importance of the intestinal mucosal wall as a mucosal immunological barrier that comes into play during interactions with gut microbiota (pathogens and commensal), luminal secretions (bile acids, and bacterial and epithelial metabolites), and ingested chemicals (food components, high fat content, heterocyclic amines, and low intake of dietary fiber) are underscored. The multifunctionality of several anti-inflammatory drugs opens a line for their application in the treatment and prevention not only in IBD but also in CRC. Current bioengineering approaches for oral delivery of anti-inflammatory agents including cytokines, genetically modified bacteria, or small molecule inhibitors of inflammation directly contribute to the early management of CRC. Limitations of the current therapeutics, which stem from the lack of complete understanding of the complex molecular interactions between the intestinal microbiota, colonic epithelial barrier, and host immune system, are also discussed.

Dextran sulphate sodium colitis in C57BL/6J mice is alleviated by Lactococcus lactis and worsened by the neutralization of Tumor necrosis Factor α

TNFα has a well-established role in inflammatory bowel disease that affects the gastrointestinal tract and is usually manifested as Crohn's disease or ulcerative colitis. We have compared Lactococcus lactis NZ9000 displaying TNFα-binding affibody with control Lactococcus lactis and with anti-TNFα antibody infliximab for the treatment of mice with dextran sulphate sodium (DSS)-induced colitis. L. lactis NZ9000 alleviated the colitis severity one week after colitis induction with DSS, more effectively when administered in preventive fashion prior to, during and after DSS administration. TNFα-binding L. lactis was less effective than control L. lactis, particularly when TNFα-binding L. lactis was administered in preventive fashion. Similarly, an apparently detrimental effect of TNFα neutralization was observed in mice that were intraperitoneally administered anti-TNFα monoclonal antibody infliximab prior to colitis induction. The highest concentrations of tissue TNFα were observed in groups without DSS colitis that were treated either with TNFα-binding L. lactis or infliximab. To conclude, we have confirmed that L. lactis exerts a protective effect on DSS-induced colitis in mice. Contrary to expectations, but in line with some reports, the neutralization of TNFα aggravated disease symptoms in the acute phase of colitis and increased TNFα concentration in colon tissue of healthy mice. Nevertheless, we have demonstrated that oral administration of bacteria with surface displayed TNFα-binding affibody can interfere significantly with TNFα signaling and mimic the infliximab response in the given animal model of colitis.

Bioengineered and biohybrid bacteria-based systems for drug delivery

The use of bacterial cells as agents of medical therapy has a long history. Research that was ignited over a century ago with the accidental infection of cancer patients has matured into a platform technology that offers the promise of opening up new potential frontiers in medical treatment. Bacterial cells exhibit unique characteristics that make them well-suited as smart drug delivery agents. Our ability to genetically manipulate the molecular machinery of these cells enables the customization of their therapeutic action as well as its precise tuning and spatio-temporal control, allowing for the design of unique, complex therapeutic functions, unmatched by current drug delivery systems. Early results have been promising, but there are still many important challenges that must be addressed. We present a review of promises and challenges of employing bioengineered bacteria in drug delivery systems and introduce the biohybrid design concept as a new additional paradigm in bacteria-based drug delivery.

Does oral exposure to cadmium and lead mediate susceptibility to colitis? The dark-and-bright sides of heavy metals in gut ecology

Although the heavy metals cadmium (Cd) and lead (Pb) are known environmental health concerns, their long-term impacts on gut ecology and susceptibility to gastrointestinal autoimmune diseases have not been extensively investigated. We sought to determine whether subchronic oral exposure to Cd or Pb is a risk factor for the development and progression of inflammatory bowel disease (IBD). Mice were exposed to various doses of CdCl2 or PbCl2 in drinking water for 1, 4 or 6 weeks prior to infection with Salmonella, the induction of colitis with dextran sodium sulfate (DSS) or trinitrobenzene sulfonic acid (TNBS). In human cell-based models, exposure to Cd and Pb is associated with reduced transepithelial electric resistance and changes in bacteria-induced cytokine responses. Although 1- and 6-week exposures did not have clear effects on the response to Salmonella infectious challenges, 1-week short-term treatments with CdCl2 tended to enhance intestinal inflammation in mice. Unexpectedly, subchronic exposure to Cd and (to a lesser extent) Pb significantly mitigated some of the symptoms of DSS-induced colitis and reduced the severity of TNBS colitis in a dose-dependent manner. The possible adaptive and immunosuppressive mechanisms by which heavy metals might reduce intestinal inflammation are explored and discussed.

Plague Vaccines: Status and Future

Three major plague pandemics caused by the gram-negative bacterium Yersinia pestis have killed nearly 200 million people in human history. Due to its extreme virulence and the ease of its transmission, Y. pestis has been used purposefully for biowarfare in the past. Currently, plague epidemics are still breaking out sporadically in most of parts of the world, including the United States. Approximately 2000 cases of plague are reported each year to the World Health Organization. However, the potential use of the bacteria in modern times as an agent of bioterrorism and the emergence of a Y. pestis strain resistant to eight antibiotics bring out severe public health concerns. Therefore, prophylactic vaccination against this disease holds the brightest prospect for its long-term prevention. Here, we summarize the progress of the current vaccine development for counteracting plague.

Interaction of mouse splenocytes and macrophages with bacterial strains in vitro: the effect of age in the immune response

Probiotics influence the immune system, both at the local and systemic level. Recent findings suggest the relation between microbiota and the immune system alters with age. Our objective was to address direct effects of six bacterial strains on immune cells from young and aged mice: Lactobacillus plantarum WCFS1, Lactobacillus casei BL23, Lactococcus lactis MG1363, Bifidobacterium breve ATCC15700, Bifidobacterium infantis ATCC15697, and Akkermansia muciniphila ATCC BAA-835. We used splenocytes and naïve or interferon-γ-stimulated bone marrow-derived macrophages (BMDM) as responder populations. All tested bacterial strains induced phenotypic and cytokine responses in splenocytes and BMDM. Based on magnitude of the cellular inflammatory response and cytokine profiles, two subgroups of bacteria were identified, i.e. L. plantarum and L. casei versus B. breve, B. infantis, and A. muciniphila. The latter group of bacteria induced high levels of cytokines produced under inflammatory conditions, including tumour necrosis factor (TNF), interleukin (IL)-6 and IL-10. Responses to L. lactis showed features of both subgroups. In addition, we compared responses by splenocytes and BMDM derived from young mice to those of aged mice, and found that splenocytes and BMDM derived from aged mice had an increased IL-10 production and dysregulated IL-6 and TNF production compared to young immune cells. Overall, our study shows differential inflammatory responses to distinct bacterial strains, and profound age-dependent effects. These findings, moreover, support the view that immune environment importantly influences bacterial immune effects.

Oral delivery of Lactococcus lactis that secretes bioactive heme oxygenase-1 alleviates development of acute colitis in mice

BACKGROUND

Mucosal delivery of therapeutic proteins using genetically modified strains of lactic acid bacteria (gmLAB) is being investigated as a new therapeutic strategy.

METHODS

We developed a strain of gmLAB, Lactococcus lactis NZ9000 (NZ-HO), which secretes the anti-inflammatory molecule recombinant mouse heme oxygenase-1 (rmHO-1). The effects of short-term continuous oral dosing with NZ-HO were evaluated in mice with dextran sulfate sodium (DSS)-induced acute colitis as a model of inflammatory bowel diseases (IBD).

RESULTS

We identified the secretion of rmHO-1 by NZ-HO. rmHO-1 was biologically active as determined with spectroscopy. Viable NZ-HO was directly delivered to the colon via oral administration, and rmHO-1 was secreted onto the colonic mucosa in mice. Acute colitis in mice was induced by free drinking of 3 % DSS in water and was accompanied by an increase in the disease activity index score and histopathological changes. Daily oral administration of NZ-HO significantly improved these colitis-associated symptoms. In addition, NZ-HO significantly increased production of the anti-inflammatory cytokine interleukin (IL)-10 and decreased the expression of pro-inflammatory cytokines such as IL-1α and IL-6 in the colon compared to a vector control strain.

CONCLUSIONS

Oral administration of NZ-HO alleviates DSS-induced acute colitis in mice. Our results suggest that NZ-HO may be a useful mucosal therapeutic agent for treating IBD.

Toll-like receptor (TLR) 2 agonists ameliorate indomethacin-induced murine ileitis by suppressing the TLR4 signaling

BACKGROUND AND AIM

Few drugs have been found satisfactory in the treatment of nonsteroidal anti-inflammatory drugs (NSAIDs)-induced enteropathy. Toll-like receptor (TLR) 4 and aberrant leukocyte migration to the intestinal mucosa are reported to be involved in the pathology of intestinal enteropathy and TLR2 agonists have been found to evoke hyposensitivity to TLR4 stimulation in vitro. In this study, we investigated whether and how lipoarabinomannan (LAM) or lipoteichoic acid (LTA), TLR2 agonists, attenuated indomethacin (IND)-induced intestinal damage.

METHODS

LAM (0.5 mg/kg) or LTA (15 mg/kg) was administered intraperitoneally to mice before IND (10 mg/kg) administration. Disease activity was evaluated macroscopically and histologically. In the migration analysis, fluorescence-labeled leukocyte movement in the intestinal microvessels was observed by intravital microscopy. Expression of P-selectin, MAdCAM-1, TLR2, TLR4, and F4/80 was observed immunohistochemically. In the in vitro analysis, RAW264.7 macrophage cells were preincubated with LAM and stimulated with lipopolysaccharide (LPS), and the mRNA expression levels of TLR4, tumor necrosis factor-α, and interleukin-12p40 were measured.

RESULTS

Pretreatment with LAM or LTA significantly decreased IND-induced injury as well as decreased leukocyte infiltration. Pretreatment with LAM decreased IND-induced TLR4 expression on F4/80(+) macrophages, the level of P-selectin expression, and leukocyte migration in the small intestinal vessels. In the in vitro study, a single administration of LAM decreased TLR4 mRNA expression and inhibited the increase in mRNA expression of inflammatory cytokines by LPS in a dose-dependent manner.

CONCLUSION

TLR2 agonists attenuated IND-induced small intestinal lesions and leukocyte infiltration probably by suppressing the TLR4 signaling pathway in tissue macrophages.

Pathological and therapeutic interactions between bacteriophages, microbes and the host in inflammatory bowel disease

The intestinal microbiome is a dynamic system of interactions between the host and its microbes. Under physiological conditions, a fine balance and mutually beneficial relationship is present. Disruption of this balance is a hallmark of inflammatory bowel disease (IBD). Whether an altered microbiome is the consequence or the cause of IBD is currently not fully understood. The pathogenesis of IBD is believed to be a complex interaction between genetic predisposition, the immune system and environmental factors. In the recent years, metagenomic studies of the human microbiome have provided useful data that are helping to assemble the IBD puzzle. In this review, we summarize and discuss current knowledge on the composition of the intestinal microbiota in IBD, host-microbe interactions and therapeutic possibilities using bacteria in IBD. Moreover, an outlook on the possible contribution of bacteriophages in the pathogenesis and therapy of IBD is provided.

Lactic acid bacteria: reviewing the potential of a promising delivery live vector for biomedical purposes

Lactic acid bacteria (LAB) have a long history of safe exploitation by humans, being used for centuries in food production and preservation and as probiotic agents to promote human health. Interestingly, some species of these Gram-positive bacteria, which are generally recognized as safe organisms by the US Food and Drug Administration (FDA), are able to survive through the gastrointestinal tract (GIT), being capable to reach and colonize the intestine, where they play an important role. Besides, during the last decades, an important effort has been done for the development of tools to use LAB as microbial cell factories for the production of proteins of interest. Given the need to develop effective strategies for the delivery of prophylactic and therapeutic molecules, LAB have appeared as an appealing option for the oral, intranasal and vaginal delivery of such molecules. So far, these genetically modified organisms have been successfully used as vehicles for delivering functional proteins to mucosal tissues in the treatment of many different pathologies including GIT related pathologies, diabetes, cancer and viral infections, among others. Interestingly, the administration of such microorganisms would suppose a significant decrease in the production cost of the treatments agents since being live organisms, such vectors would be able to autonomously amplify and produce and deliver the protein of interest. In this context, this review aims to provide an overview of the use of LAB engineered as a promising alternative as well as a safety delivery platform of recombinant proteins for the treatment of a wide range of diseases.

Immunomodulation properties of multi-species fermented milks

Dairy propionibacteria (PAB) are used as a ripening starter in combination with Lactic acid bacteria (LAB) for dairy products such as Swiss-type cheese. LAB and PAB have also been studied for their probiotic properties but little is still known about their individual and/or synergistic beneficial effects within dairy matrices. In the context of a rising incidence of Inflammatory Bowel Diseases, it has become crucial to evaluate the immunomodulatory potential of bacteria ingested in large numbers via dairy products. We therefore selected different strains and combinations of technological LAB and PAB. We determined their immunomodulatory potential by IL-10 and IL-12 induction, in human peripheral blood mononuclear cells, on either single or mixed cultures, grown on laboratory medium or directly in milk. Milk was fermented with selected anti-inflammatory strains of LAB or PAB/LAB mixed cultures and the resulting bacterial fractions were also evaluated for these properties, together with starter viability and optimum technological aspects. The most promising fermented milks were evaluated in the context of TNBS- or DSS-induced colitis in mice. The improvement in inflammatory parameters evidenced an alleviation of colitis symptoms as a result of fermented milk consumption. This effect was clearly strain-dependent and modulated by growth within a fermented dairy product. These findings offer new tools and perspectives for the development of immunomodulatory fermented dairy products for targeted populations.

Antioxidant properties of wine lactic acid bacteria: Oenococcus oeni

The most prominent trait of wine lactic acid bacteria (LAB) is their capacity to cope with a hostile environment. However, wine-derived LAB may confer inherent probiotic properties that have not been explored. In this study, the antioxidant activities of 19 strains of Oenococcus oeni were measured in vitro. The results suggested that the antioxidative parameters were widely dispersed, irrespective of the evaluation methods used, which indicated that antioxidative properties depended on the strain and culture medium. The antioxidant mechanisms of O. oeni could be assigned to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability, reactive oxygen species (ROS) scavenging ability, iron ion chelation (FE), glutathione system, ferric reducing ability of plasma (FRAP), reduction activity (RA), inhibition of ascorbic oxidation (TAA), and linoleic acid oxidation (TLA) abilities. Moreover, most of the O. oeni strains exhibited good survival abilities at low pH values (pH 1.8), simulated intestine juice and bile salts (1 %), suggesting their good adaptation to gastrointestinal conditions and high bile resistance abilities. O. oeni SD-1e, SD-2gf, 31-DH, and SD-2d with promising potential probiotic characteristics were segregated by the principal component analysis (PCA). O. oeni strains likely serve as defensive agents in the intestinal microbial ecosystem and overcome exogenous and endogenous oxidative stress. Although further studies are needed to elucidate the multiple mechanisms involved, the study reported herein confirms the effectiveness of O. oeni in the defense against in vitro oxidative stress.

Probiotics: an update

OBJECTIVE

Triggered by the growing knowledge on the link between the intestinal microbiome and human health, the interest in probiotics is ever increasing. The authors aimed to review the recent literature on probiotics, from definitions to clinical benefits, with emphasis on children.

SOURCES

Relevant literature from searches of PubMed, CINAHL, and recent consensus statements were reviewed.

SUMMARY OF THE FINDINGS

While a balanced microbiome is related to health, an imbalanced microbiome or dysbiosis is related to many health problems both within the gastro-intestinal tract, such as diarrhea and inflammatory bowel disease, and outside the gastro-intestinal tract such as obesity and allergy. In this context, a strict regulation of probiotics with health claims is urgent, because the vast majority of these products are commercialized as food (supplements), claiming health benefits that are often not substantiated with clinically relevant evidence. The major indications of probiotics are in the area of the prevention and treatment of gastro-intestinal related disorders, but more data has become available on extra-intestinal indications. At least two published randomized controlled trials with the commercialized probiotic product in the claimed indication are a minimal condition before a claim can be sustained. Today, Lactobacillus rhamnosus GG and Saccharomyces boulardii are the best-studied strains. Although adverse effects have sporadically been reported, these probiotics can be considered as safe.

CONCLUSIONS

Although regulation is improving, more stringent definitions are still required. Evidence of clinical benefit is accumulating, although still missing in many areas. Misuse and use of products that have not been validated constitute potential drawbacks.

Drug delivery strategies in the therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a frequently occurring disease in young people, which is characterized by a chronic inflammation of the gastrointestinal tract. The therapy of IBD is dominated by the administration of anti-inflammatory and immunosuppressive drugs, which suppress the intestinal inflammatory burden and improve the disease-related symptoms. Established treatment strategies are characterized by a limited therapeutical efficacy and the occurrence of adverse drug reactions. Thus, the development of novel disease-targeted drug delivery strategies is intended for a more effective therapy and demonstrates the potential to address unmet medical needs. This review gives an overview about the established as well as future-oriented drug targeting strategies, including intestine targeting by conventional drug delivery systems (DDS), disease targeted drug delivery by synthetic DDS and disease targeted drug delivery by biological DDS. Furthermore, this review analyses the targeting mechanisms of the respective DDS and discusses the possible field of utilization in IBD.

Modulation of peanut-induced allergic immune responses by oral lactic acid bacteria-based vaccines in mice

Peanut allergy (PNA) has becoming a non-negligible health concern worldwide. Thus far, allergen-specific immunotherapy aimed at inducing mucosal tolerance has widely been regarded as a major management strategy for PNA. The safety profiles and the intrinsic probiotic properties of lactic acid bacteria (LAB) render them attractive delivery vehicles for mucosal vaccines. In the present study, we exploited genetically modified Lactococcus lactis to produce peanut allergen Ara h 2 via different protein-targeting systems and their immunomodulatory potency for allergic immune responses in mice were investigated. By comparison with the strain expressing the cytoplasmic form of Ara h 2 (LL1), the strains expressing the secreted and anchored forms of Ara h 2 (LL2 and LL3) were more potent in redirecting a Th2-polarized to a non-allergic Th1 immune responses. Induction of SIgA and regulatory T cells were also observed at the local levels by orally administration of recombinant L. lactis. Our results indicate that allergen-producing L. lactis strains modulated allergic immune responses and may be developed as promising mucosal vaccines for managing allergic diseases.

Effects in the use of a genetically engineered strain of Lactococcus lactis delivering in situ IL-10 as a therapy to treat low-grade colon inflammation

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by chronic abdominal pain, discomfort, and bloating. Interestingly, there is now evidence of the presence of a low-grade inflammatory status in many IBS patients, including histopathological and mucosal cytokine levels in the colon, as well as the presence of IBS-like symptoms in quiescent inflammatory bowel disease (IBD). The use of a genetically engineered food-grade bacterium, such as Lactococcus lactis, secreting the anti-inflammatory cytokine IL-10 has been proven by many pre-clinical studies to be a successful therapy to treat colon inflammation. In this study, we first reproduced the recovery-recurrence periods observed in IBS-patients in a new chronic model characterized by 2 episodes of DiNitro-BenzeneSulfonic-acid (DNBS)-challenge and we tested the effects of a recombinant strain of L. lactis secreting IL-10 under a Stress-Inducible Controlled Expression (SICE) system. In vivo gut permeability, colonic serotonin levels, cytokine profiles, and spleen cell populations were then measured as readouts of a low-grade inflammation. In addition, since there is increasing evidence that gut microbiota tightly regulates gut barrier function, tight junction proteins were also measured by qRT-PCR after administration of recombinant L. lactis in DNBS-treated mice. Strikingly, oral administration of L. lactis secreting active IL-10 in mice resulted in significant protective effects in terms of permeability, immune activation, and gut-function parameters. Although genetically engineered bacteria are, for now, used only as a "proof-of-concept," our study validates the interest in the use of the novel SICE system in L. lactis to express therapeutic molecules, such as IL-10, locally at mucosal surfaces.

The commensal bacterium Faecalibacterium prausnitzii is protective in DNBS-induced chronic moderate and severe colitis models

BACKGROUND

The abundance of Faecalibacterium prausnitzii, an abundant and representative bacterium of Firmicutes phylum, has consistently been observed to be lower in patients with Crohn's disease than in healthy individuals. We have shown that both F. prausnitzii and its culture supernatant (SN) have anti-inflammatory and protective effects in a TNBS-induced acute colitis mouse model. Here, we tested the effects of both F. prausnitzii and its SN in moderate and severe DNBS-induced chronic colitis mouse models.

METHODS

Colitis was induced by intrarectal administration of DNBS. After either 4 or 10 days of recovery (severe and moderate protocols, respectively), groups of mice were intragastrically administered either with F. prausnitzii A2-165 or with its culture SN for 7 or 10 days. Three days before being sacrificed, colitis was reactivated by administration of a lower dose of DNBS. The severity of colitis at the time of being sacrificed was assessed by weight loss and macroscopic and microscopic scores. Myeloperoxidase (MPO) activity, cytokine levels, lymphocyte populations, and changes in microbiota were studied.

RESULTS

Intragastric administration of either F. prausnitzii or its SN led to a significant decrease in colitis severity in both severe and moderate chronic colitis models. The lower severity of colitis was associated with down-regulation of MPO, pro-inflammatory cytokines, and T-cell levels.

CONCLUSIONS

We show, for the first time, protective effects of both F. prausnitzii and its SN during both the period of recovery from chronic colitis and colitis reactivation. These results provide further evidence that F. prausnitzii is an anti-inflammatory bacterium with therapeutic potential for patients with inflammatory bowel disease.

In vivo reprogramming in inflammatory bowel disease

The direct reprogramming of somatic cells has immense implications in various areas of medicine. Although remarkable progress has been made in developing novel reprogramming methods, the efficiency and fidelity of reprogramming still need to be improved. Inflammatory bowel disease (IBD) involves chronic inflammatory diseases of the gastrointestinal tract with a complex etiology caused by various genetic, immunological and environmental factors. Recently, the role of stem cells has been proposed in pathogenesis and therapy of IBD. However, the efficiency and the safety of the stem cell treatments depend on the origin of the stem cell and the administration method. We hypothesize that the reprogramming of the intestinal cells into a pluripotent state is of huge importance for IBD therapy and prevention. The vectors carrying reprogramming genes encoding pluripotency factors can be transferred to the damaged tissue, in this case the intestine, by means of invasive bacterial vectors able to colonize colon mucosa. Reconstruction of tissues in vivo might avoid problems encountered in tissue rebuilding in vitro because of lack of appropriate scaffolds and microenvironments. Herein we present a review of recent literature and a perspective of in vivo reprogramming in IBD using bacterial vectors and analyze the rationale for such approach.

Role of commensal and probiotic bacteria in human health: a focus on inflammatory bowel disease

The human gut is one of the most complex ecosystems, composed of 1013-1014 microorganisms which play an important role in human health. In addition, some food products contain live bacteria which transit through our gastrointestinal tract and could exert beneficial effects on our health (known as probiotic effect). Among the numerous proposed health benefits attributed to commensal and probiotic bacteria, their capacity to interact with the host immune system is now well demonstrated. Currently, the use of recombinant lactic acid bacteria to deliver compounds of health interest is gaining importance as an extension of the probiotic concept. This review summarizes some of the recent findings and perspectives in the study of the crosstalk of both commensal and probiotic bacteria with the human host as well as the latest studies in recombinant commensal and probiotic bacteria. Our aim is to highlight the potential roles of recombinant bacteria in this ecosystem.