NOD dendritic cells stimulated with Lactobacilli preferentially produce IL-10 versus IL-12 and decrease diabetes incidence

A Monocytic Barrier to the Humanization of Immunodeficient Mice

Mice with severe immunodeficiencies have become very important tools for studying foreign cells in an in vivo environment. Xenotransplants can be used to model cells from many species, although most often, mice are humanized through the transplantation of human cells or tissues to meet the needs of medical research. The development of immunodeficient mice is reviewed leading up to the current state-of-the-art strains, such as the NOD-scid-gamma (NSG) mouse. NSG mice are excellent hosts for human hematopoietic stem cell transplants or immune reconstitution through transfusion of human peripheral blood mononuclear cells. However, barriers to full hematopoietic engraftment still remain; notably, the survival of human cells in the circulation is brief, which limits overall hematological and immune reconstitution. Reports have indicated a critical role for monocytic cells - monocytes, macrophages, and dendritic cells - in the clearance of xenogeneic cells from circulation. Various aspects of the NOD genetic background that affect monocytic cell growth, maturation, and function that are favorable to human cell transplantation are discussed. Important receptors, such as SIRPα, that form a part of the innate immune system and enable the recognition and phagocytosis of foreign cells by monocytic cells are reviewed. The development of humanized mouse models has taken decades of work in creating more immunodeficient mice, genetic modification of these mice to express human genes, and refinement of transplant techniques to optimize engraftment. Future advances may focus on the monocytic cells of the host to find ways for further engraftment and survival of xenogeneic cells.

Stimulation of Probiotic Bacteria Induces Release of Membrane Vesicles with Augmented Anti-inflammatory Activity

During infection, inflammation is an important contributor to tissue regeneration and healing, but it may also negatively affect these processes should chronic overstimulation take place. Similar issues arise in chronic inflammatory gastrointestinal diseases such as inflammatory bowel diseases or celiac disease, which show increasing incidences worldwide. For these dispositions, probiotic microorganisms, including lactobacilli, are studied as an adjuvant therapy to counterbalance gut dysbiosis. However, not all who are affected can benefit from the probiotic treatment, as immunosuppressed or hospitalized patients can suffer from bacteremia or sepsis when living microorganisms are administered. A promising alternative is the treatment with bacteria-derived membrane vesicles that confer similar beneficial effects as the progenitor strains themselves. Membrane vesicles from lactobacilli have shown anti-inflammatory therapeutic effects, but it remains unclear whether the stimulation of probiotics induces vesicles that are more efficient. Here, the influence of culture conditions on the anti-inflammatory characteristics of Lactobacillus membrane vesicles was investigated. We reveal that the culture conditions of two Lactobacillus strains, namely, L. casei and L. plantarum, can be optimized to increase the anti-inflammatory effect of their vesicles. Five different cultivation conditions were tested, including pH manipulation, agitation rate, and oxygen supply, and the produced membrane vesicles were characterized physico-chemically regarding size, yield, and zeta potential. We furthermore analyzed the anti-inflammatory effect of the purified vesicles in macrophage inflammation models. Compared to standard cultivation conditions, vesicles obtained from L. casei cultured at pH 6.5 and agitation induced the strongest interleukin-10 release and tumor necrosis factor-α reduction. For L. plantarum, medium adjusted to pH 5 had the most pronounced effect on the anti-inflammatory activity of their vesicles. Our results reveal that the anti-inflammatory effect of probiotic vesicles may be potentiated by expanding different cultivation conditions for lactobacilli. This study creates an important base for the utilization of probiotic membrane vesicles to treat inflammation.

Altered Metabolome of Lipids and Amino Acids Species: A Source of Early Signature Biomarkers of T2DM

Diabetes mellitus, a disease of modern civilization, is considered the major mainstay of mortalities around the globe. A great number of biochemical changes have been proposed to occur at metabolic levels between perturbed glucose, amino acid, and lipid metabolism to finally diagnoe diabetes mellitus. This window period, which varies from person to person, provides us with a unique opportunity for early detection, delaying, deferral and even prevention of diabetes. The early detection of hyperglycemia and dyslipidemia is based upon the detection and identification of biomarkers originating from perturbed glucose, amino acid, and lipid metabolism. The emerging “OMICS” technologies, such as metabolomics coupled with statistical and bioinformatics tools, proved to be quite useful to study changes in physiological and biochemical processes at the metabolic level prior to an eventual diagnosis of DM. Approximately 300–400 such metabolites have been reported in the literature and are considered as predicting or risk factor-reporting metabolic biomarkers for this metabolic disorder. Most of these metabolites belong to major classes of lipids, amino acids and glucose. Therefore, this review represents a snapshot of these perturbed plasma/serum/urinary metabolic biomarkers showing a significant correlation with the future onset of diabetes and providing a foundation for novel early diagnosis and monitoring the progress of metabolic syndrome at early symptomatic stages. As most metabolites also find their origin from gut microflora, metabolism and composition of gut microflora also vary between healthy and diabetic persons, so we also summarize the early changes in the gut microbiome which can be used for the early diagnosis of diabetes.

Feeding lactobacilli impacts lupus progression in (NZBxNZW)F1 lupus-prone mice by enhancing immunoregulation

Although the relationship between autoimmunity and microorganisms is complex, there is evidence that microorganisms can prevent the development of various autoimmune diseases. Lactobacilli are beneficial gut bacteria that play an important role in immune system development. The goals of this study were to assess the ability of three different strains of lactobacilli (L. casei B255, L. reuteri DSM 17509 and L. plantarum LP299v) to control lupus development/progression in (NZBxNZW)F1 (BWF1) lupus-prone mice before and after disease onset, and identify the mechanisms mediating protection. BWF1 mice fed with individual L. casei or L. reuteri before disease onset exhibited delayed lupus onset and increased survival, while feeding L. plantarum had little impact. In vitro treatment of BWF1 dendritic cells with individual lactobacilli strains upregulated IL-10 production to various extents, with L. casei being the most effective. The protection mediated by L. casei was associated with upregulation of B7-1 and B7-2 by antigen presenting cells, two costimulatory molecules important for regulatory T cell (Treg) induction. Moreover, feeding L. casei lead to increased percentages of CD4⁺Foxp3⁺ Tregs and IL10-producing T cells in the lymphoid organs of treated mice. More importantly, mice fed L. casei after disease onset remained stable for several months, i.e. exhibited delayed anti-nucleic acid production and kidney disease progression, and increased survival. Therefore, feeding lactobacilli appears to delay lupus progression possibly via mechanisms involving Treg induction and IL-10 production. Altogether, these data support the notion that ingestion of lactobacilli, with immunoregulatory properties, may be a viable strategy for controlling disease development and progression in patients with lupus, i.e. extending remission length and reducing flare frequency.

Fucoidan prevent murine autoimmune diabetes via suppression TLR4-signaling pathways, regulation DC/Treg induced immune tolerance and improving gut microecology

Background

This study was to investigate the effect and its possible mechanism of fucoidan on the development of spontaneous autoimmune diabetes in non-obese diabetic (NOD) mice.

Methods

7-week-old NOD mice were randomly divided into three groups: control group, low-dose (300 mg/kg) and high-dose (600 mg/kg) fucoidan-treatment groups. After 5 weeks of treatment, 10 mice per group were randomly selected to be sacrificed after feces collection. The remaining 12 mice per group were fed until 26 weeks of age to assess the incidence of diabetes.

Results

Treatment with fucoidan increased serum insulin level, delayed the onset and decreased the development of diabetes in NOD mice. Fucoidan reduced the levels of strong Th1 proinflammatory cytokines, but induced Th2-bias ed. cytokine response. And dentridic cells (DCs) in fucoidan treatment group were characterized as low expression of MHC class II and CD86 molecules. TLR4 expressions and the downstream molecules in pancreas were down-regulated in fucoidan-treated groups. There were significant differences in the composition of gut flora between NOD control group and fucoidan group. Lactobacillus and Akkermansia were significantly enriched in fucoidan group.

Conclusions

Fucoidan could prevent the development of autoimmune diabetes in NOD mice via regulating DC/Treg induced immune tolerance, improving gut microecology, down-regulating TLR4 signaling pathway, and maintaining pancreatic internal environment.

Optimal Tolerogenic Dendritic Cells in Type 1 Diabetes (T1D) Therapy: What Can We Learn From Non-obese Diabetic (NOD) Mouse Models?

Tolerogenic dendritic cells (tolDCs) are explored as a promising standalone or combination therapy in type 1 diabetes (T1D). The therapeutic application of tolDCs, including in human trials, has been tested also in other autoimmune diseases, however, T1D displays some unique features. In addition, unlike in several disease-induced animal models of autoimmune diseases, the prevalent animal model for T1D, the NOD mouse, develops diabetes spontaneously. This review compares evidence of various tolDCs approaches obtained from animal (mainly NOD) models of T1D with a focus on parameters of this cell-based therapy such as protocols of tolDC preparation, antigen-specific vs. unspecific approaches, doses of tolDCs and/or autoantigens, application schemes, application routes, the migration of tolDCs as well as their preventive, early pre-onset intervention or curative effects. This review also discusses perspectives of tolDC therapy and areas of preclinical research that are in need of better clarification in animal models in a quest for effective and optimal tolDC therapies of T1D in humans.

Gut Microbiota, Host Organism, and Diet Trialogue in Diabetes and Obesity

The gastrointestinal tract with its microbiota is a complex, open, and integrated ecosystem with a high environmental exposure. It is widely accepted that the healthy gut microbiotais essential for host homeostasis and immunostasis, harboring an enormous number and variety of microorganisms and genes tailored by hundreds of exogenous and intrinsic host factors. The occurrence of dysbiosis may contribute to host vulnerability and progression to a large spectrum of infectious and non-communicable diseases, including diabetes and obesity, two metabolic disorders that are showing an endemic trend nowadays. There is an urgent need to develop efficient strategies to prevent and treat metabolic disorders such as diabetes and obesity which are often associated with serious complications. In this paper, we give an overview on the implications of gut microbiota in diabesity, with a focus on the triangle gut microbiota—diet-host metabolism and on the way to manipulate the gut microbial ecosystem toward achieving novel diagnosis and predictive biomarkers with the final goal of reestablishing the healthy metabolic condition. The current research data regarding the precision/personalized nutrition suggest that dietary interventions, including administration of pre-, pro-, and syn-biotics, as well as antibiotic treatment should be individually tailored to prevent chronic diseases based on the genetic background, food and beverage consumption, nutrient intake, microbiome, metabolome, and other omic profiles.

Adipose tissue inflammation and metabolic syndrome. The proactive role of probiotics

PURPOSE

The first part of this review focuses on the role of cells and molecules of adipose tissue involved in metabolic syndrome-induced inflammation and in the maintenance of this pathology. In the second part of the review, the potential role of probiotics-modulating metabolic syndrome-related inflammatory components is summarized and discussed.

METHODS

The search for the current scientific literature was carried out using ScienceDirect, PubMed, and Google Scholar search engines. The keywords used were: metabolic syndrome, obesity, insulin resistant, adipose tissue, adipose tissue inflammation, chronic low-grade inflammation, immune cells, adipokines, cytokines, probiotics, and gut microbiota.

RESULTS AND CONCLUSIONS

Chronic low-grade inflammation that characterized metabolic syndrome can contribute to the development of the metabolic dysfunctions involved in the pathogenesis of its comorbidities. Adipose tissue is a complex organ that performs metabolic and immune functions. During metabolic syndrome, an imbalance in the inflammatory components of adipose tissue (immune cells, cytokines, and adipocytokines), which shift from an anti-inflammatory to a pro-inflammatory profile, can provoke metabolic syndrome linked complications. Further knowledge concerning the immune function of adipose tissue may contribute to finding better alternatives for the treatment or prevention of such disorders. The control of inflammation could result in the management of many of the pathologies related to metabolic syndrome. Due to the strong evidence that gut microbiota composition plays a role modulating the body weight, adipose tissue, and the prevalence of a low-grade inflammatory status, probiotics emerge as valuable tools for the prevention of metabolic syndrome and health recovery.

The causes and consequences of variation in human cytokine production in health

Cytokines are important cell-signaling molecules that activate and modulate immune responses. Major factors influencing cytokine variation in healthy individuals are host genetics, non-heritable factors and the microbiome. Genetic variation accounts for a significant part of heterogeneity in cytokine production by peripheral blood mononuclear cells. Variation in cytokines such as IL-6 and IL-6Ra is strongly influenced by heritability, suggesting an evolutionarily pressure for their genetic regulation that potentially contributes to differences in immune responsiveness between human populations. Non-heritable factors, including age, body weight and environmental variables such as seasonality, drive variation in baseline cytokine levels. Age further affects pathogen-induced lymphocyte-derived cytokine responses, whereas seasonality affects monocyte-derived cytokine production in response to influenza virus, Coxiella burnetti or Cryptococcus neoformans. Another influential factor that shapes the immune system is the human microbiome. Microbes and microbial products (e.g. short-chain fatty acids and tryptophan metabolites) possess strong immunomodulatory effects, induce regulatory T cells and lead to the diversification of B cells and the production of specific antibodies. In particular, differential TNFα and IFNγ production is associated with the gut microbiome. Understanding causes of variation in the healthy human immune system can reveal factors that lead to aberrant cytokine production in immune-related disorders.

Maternal Antibiotic Treatment Protects Offspring from Diabetes Development in Nonobese Diabetic Mice by Generation of Tolerogenic APCs

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease that involves the slow, progressive destruction of islet β cells and loss of insulin production, as a result of interaction with environmental factors, in genetically susceptible individuals. The gut microbiome is established very early in life. Commensal microbiota establish mutualism with the host and form an important part of the environment to which individuals are exposed in the gut, providing nutrients and shaping immune responses. In this study, we studied the impact of targeting most Gram-negative bacteria in the gut of NOD mice at different time points in their life, using a combination of three antibiotics--neomycin, polymyxin B, and streptomycin--on diabetes development. We found that the prenatal period is a critical time for shaping the immune tolerance in the progeny, influencing development of autoimmune diabetes. Prenatal neomycin, polymyxin B, and streptomycin treatment protected NOD mice from diabetes development through alterations in the gut microbiota, as well as induction of tolerogenic APCs, which led to reduced activation of diabetogenic CD8 T cells. Most importantly, we found that the protective effect was age dependent, and the most profound protection was found when the mice were treated before birth. This indicates the importance of the prenatal environment and early exposure to commensal bacteria in shaping the host immune system and health.

Probiotics as potential biotherapeutics in the management of type 2 diabetes - prospects and perspectives

Diabetes mellitus is a looming epidemic worldwide, affecting almost all major sections of society, creating burdens on global health and economy. A large number of studies have identified a series of multiple risk factors such as genetic predisposition, epigenetic changes, unhealthy lifestyle, and altered gut microbiota that cause increased adiposity, β-cell dysfunction, hyperglycemia, hypercholesterolemia, adiposity, dyslipidaemia, metabolic endotoxemia, systemic inflammation, intestinal permeability (leaky gut), defective secretion of incretins and oxidative stress associated with type 2 diabetes (T2D). Recent studies have proposed multifactorial interventions including dietary manipulation in the management of T2D. The same interventions have also been recommended by many national and international diabetes associations. These studies are aimed at deciphering the gut microbial influence on health and disease. Interestingly, results from several genomic, metagenomic and metabolomic studies have provided substantial information to target gut microbiota by dietary interventions for the management of T2D. Probiotics particularly lactobacilli and bifidobacteria have recently emerged as the prospective biotherapeutics with proven efficacy demonstrated in various in vitro and in vivo animal models adequately supported with their established multifunctional roles and mechanism of action for the prevention and disease treatment. The dietary interventions in conjunction with probiotics - a novel multifactorial strategy to abrogate progression and development of diabetes - hold considerable promise through improving the altered gut microbial composition and by targeting all the possible risk factors. This review will highlight the new developments in probiotic interventions and future prospects for exploring probiotic therapy in the prevention and control of lifestyle diseases like T2D.

Gut microbiota, immunity, and disease: a complex relationship

Our immune system has evolved to recognize and eradicate pathogenic microbes. However, we have a symbiotic relationship with multiple species of bacteria that occupy the gut and comprise the natural commensal flora or microbiota. The microbiota is critically important for the breakdown of nutrients, and also assists in preventing colonization by potentially pathogenic bacteria. In addition, the gut commensal bacteria appear to be critical for the development of an optimally functioning immune system. Various studies have shown that individual species of the microbiota can induce very different types of immune cells (e.g., Th17 cells, Foxp3(+) regulatory T cells) and responses, suggesting that the composition of the microbiota can have an important influence on the immune response. Although the microbiota resides in the gut, it appears to have a significant impact on the systemic immune response. Indeed, specific gut commensal bacteria have been shown to affect disease development in organs other than the gut, and depending on the species, have been found to have a wide range of effects on diseases from induction and exacerbation to inhibition and protection. In this review, we will focus on the role that the gut microbiota plays in the development and progression of inflammatory/autoimmune disease, and we will also touch upon its role in allergy and cancer.