The role of the intestinal microbiota in type 1 diabetes

The role of intestinal flora on tumor immunotherapy: recent progress and treatment implications

Immunotherapy, specifically immune checkpoint inhibitors, has emerged as a promising approach for treating malignant tumors. The gut, housing approximately 70 % of the body's immune cells, is abundantly populated with gut bacteria that actively interact with the host's immune system. Different bacterial species within the intestinal flora are in a delicate equilibrium and mutually regulate each other. However, when this balance is disrupted, pathogenic microorganisms can dominate, adversely affecting the host's metabolism and immunity, ultimately promoting the development of disease. Emerging researches highlight the potential of interventions such as fecal microflora transplantation (FMT) to improve antitumor immune response and reduce the toxicity of immunotherapy. These remarkable findings suggest the major role of intestinal flora in the development of cancer immunotherapy and led us to the hypothesis that intestinal flora transplantation may be a new breakthrough in modifying immunotherapy side effects.

Fecal microbiota transplantation for the management of autoimmune diseases: Potential mechanisms and challenges

Autoimmune diseases (AIDs) are a series of immune-mediated lethal diseases featured by over-activated immune cells attacking healthy self-tissues and organs due to the loss of immune tolerance, which always causes severe irreversible systematical organ damage and threatens human health heavily. To date, there are still no definitive cures for the treatment of AIDs due to their pathogenesis has not been clearly understood. Besides, the current clinical treatments of AIDs majorly rely on glucocorticoids and immune suppressors, which can lead to serious side effects. In the past years, there are increasing studies demonstrating that an imbalance of gut microbiota is intimately related to the pathogenesis of various AIDs, shedding light on the development of therapeutics by targeting the gut microbiota for the management of AIDs. Among all the approaches targeting the gut microbiota, fecal microbiota transplantation (FMT) has attracted increasing interest, and it has been proposed as a possible strategy to intervene in the homeostasis of gut microbiota for the treatment of various diseases. However, despite the reported good curative effects and clinical studies conducted on FMT, the detailed mechanisms of FMT for the effective treatment of those diseases have not been figured out. To fully understand the mechanisms of the therapeutic effects of FMT on AIDs and improve the therapeutic efficacy of FMT treatment, a systematic review of this topic is necessary. Hence, in this review paper, the potential mechanisms of FMT for the treatment of various AIDs were summarized, including promotion, shaping, activation, or inhibition of the host immune system via the interactions between the microorganisms and the gut immune system, gut-brain, gut-liver, gut-kidney axis, and so on. Then, applications of FMT for the treatment of various AIDs were detailed presented. Finally, the current challenges and potential solutions for the development of FMT formulations and FMT therapeutics were comprehensively discussed.

Gut microbiome and blood glucose control in type 1 diabetes: a systematic review

Objective

The risk of developing micro- and macrovascular complications is higher for individuals with type 1 diabetes (T1D). Numerous studies have indicated variations in gut microbial composition between healthy individuals and those with T1D. These changes in the gut ecosystem may lead to inflammation, modifications in intestinal permeability, and alterations in metabolites. Such effects can collectively impact the metabolic regulation system, thereby influencing blood glucose control. This review aims to explore the relationship between the gut microbiome, inflammation, and blood glucose parameters in patients with T1D.

Methods

Google Scholar, PubMed, and Web of Science were systematically searched from 2003 to 2023 using the following keywords: "gut microbiota," "gut microbiome," "bacteria," "T1D," "type 1 diabetes," "autoimmune diabetes," "glycemic control," "glucose control," "HbA1c," "inflammation," "inflammatory," and "cytokine." The examination has shown 18,680 articles with relevant keywords. After the exclusion of irrelevant articles, seven observational papers showed a distinct gut microbial signature in T1D patients.

Results

This review shows that, in T1D patients, HbA1c level was negatively correlated with abundance of Prevotella, Faecalibacterium, and Ruminococcaceae and positively correlated with abundance of Dorea formicigenerans, Bacteroidetes, Lactobacillales, and Bacteriodes. Instead, Bifidobacteria was negatively correlated with fasting blood glucose. In addition, there was a positive correlation between Clostridiaceae and time in range. Furthermore, a positive correlation between inflammatory parameters and gut dysbiosis was revealed in T1D patients.

Conclusion

We draw the conclusion that the gut microbiome profiles of T1D patients and healthy controls differ. Patients with T1D may experience leaky gut, bacterial translocation, inflammation, and poor glucose management due to microbiome dysbiosis. Direct manipulation of the gut microbiome in humans and its effects on gut permeability and glycemic control, however, have not been thoroughly investigated. Future research should therefore thoroughly examine other potential pathophysiological mechanisms in larger studies.

MetaPro: a scalable and reproducible data processing and analysis pipeline for metatranscriptomic investigation of microbial communities

BACKGROUND

Whole microbiome RNASeq (metatranscriptomics) has emerged as a powerful technology to functionally interrogate microbial communities. A key challenge is how best to process, analyze, and interpret these complex datasets. In a typical application, a single metatranscriptomic dataset may comprise from tens to hundreds of millions of sequence reads. These reads must first be processed and filtered for low quality and potential contaminants, before being annotated with taxonomic and functional labels and subsequently collated to generate global bacterial gene expression profiles.

RESULTS

Here, we present MetaPro, a flexible, massively scalable metatranscriptomic data analysis pipeline that is cross-platform compatible through its implementation within a Docker framework. MetaPro starts with raw sequence read input (single-end or paired-end reads) and processes them through a tiered series of filtering, assembly, and annotation steps. In addition to yielding a final list of bacterial genes and their relative expression, MetaPro delivers a taxonomic breakdown based on the consensus of complementary prediction algorithms, together with a focused breakdown of enzymes, readily visualized through the Cytoscape network visualization tool. We benchmark the performance of MetaPro against two current state-of-the-art pipelines and demonstrate improved performance and functionality.

CONCLUSIONS

MetaPro represents an effective integrated solution for the processing and analysis of metatranscriptomic datasets. Its modular architecture allows new algorithms to be deployed as they are developed, ensuring its longevity. To aid user uptake of the pipeline, MetaPro, together with an established tutorial that has been developed for educational purposes, is made freely available at https://github.com/ParkinsonLab/MetaPro . The software is freely available under the GNU general public license v3. Video Abstract.

Immune Fingerprint in Diabetes: Ocular Surface and Retinal Inflammation

Diabetes is a prevalent global health issue associated with significant morbidity and mortality. Diabetic retinopathy (DR) is a well-known inflammatory, neurovascular complication of diabetes and a leading cause of preventable blindness in developed countries among working-age adults. However, the ocular surface components of diabetic eyes are also at risk of damage due to uncontrolled diabetes, which is often overlooked. Inflammatory changes in the corneas of diabetic patients indicate that inflammation plays a significant role in diabetic complications, much like in DR. The eye's immune privilege restricts immune and inflammatory responses, and the cornea and retina have a complex network of innate immune cells that maintain immune homeostasis. Nevertheless, low-grade inflammation in diabetes contributes to immune dysregulation. This article aims to provide an overview and discussion of how diabetes affects the ocular immune system's main components, immune-competent cells, and inflammatory mediators. By understanding these effects, potential interventions and treatments may be developed to improve the ocular health of diabetic patients.

Dietary supplementation with a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde improves intestinal barrier function in weaning piglets

BACKGROUND

The authors previously prepared a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde (MEEO). This study aimed to evaluate the effect of MEEO on the intestinal mucosal barrier and homeostasis in weaning piglets. A comparison of the effect of MEEO versus chlortetracycline (CTC) was performed in this study.

RESULTS

Piglets were divided into three groups - control (Con), MEEO, and CTC groups - and raised for 28 days. The results showed that MEEO significantly elevated the ratio of the villus height and the crypt depth in the jejunum and decreased the crypt depth in the ileum compared with the other groups (P < 0.05); it also upregulated the messenger ribonucleic acid (mRNA) expression of tight junction protein in the small intestine. Compared with the Con group, MEEO increased the concentration of secretory immunoglobulin A (sIgA), cathelicidin antimicrobial peptides (CAMP), and interleukin 10 (IL-10), while decreasing the interleukin 1 beta (IL-1β) concentration in both jejunal and ileal mucosa (P < 0.05). The mRNA expression of jejunal mucosal MUC1 and ileal mucosal MUC2 was increased in the MEEO group compared with the other groups (P < 0.05). Intestinal microbial analysis showed that dietary treatment had little impact on the ileal microbial structure. A significant rise in the genus Lactobacillus was, however, found in the MEEO group. There is a positive correlation between the Lactobacillus and sIgA, and between the Lactobacillus and CAMP, indicating that an improvement in the mucosal barrier function by the addition of MEEO may be associated with the proliferation of Lactobacillus.

CONCLUSION

Dietary supplementation with MEEO improves intestinal barrier function in weaning piglets, the effect of which was superior to CTC. © 2022 Society of Chemical Industry.

Advances in research of microbiome regulation as a therapy for liver failure

The intestinal flora of the human body is complex and diverse, and the structure and composition of the intestinal micro-ecosystem formed by the intestinal flora are complicated. Studies have shown that the imbalance of the intestinal micro-ecosystem is closely related to the occurrence and development of liver failure, and the degree of intestinal microecological imbalance is significantly correlated with the severity of liver failure. Therefore, the role of intestinal microbiome regulation in the treatment of liver failure and the improvement of prognosis has increasingly attracting the attention of scholars. However, due to the complexity of the composition and structure of the intestinal flora and its mechanism of action involved in the development of liver failure, the application of intestinal microbiome regulation in the clinic is limited to a certain extent. In this paper, we review the research progress of microbiome regulation as a therapy for liver failure.

Time dependent effects of prolonged hyperglycemia in zebrafish brain and retina

Prolonged hyperglycemia causes long-term vision complications and an increased risk of cognitive deficits. High blood sugar also confers an osmotic load/stress to cells. We assessed behavioral and neurochemical changes in zebrafish brain and retina following prolonged hyperglycemia for 4-weeks or 8-weeks. At each time point, behavior was assessed using 3-chamber choice task and optomotor response; tissue was then collected and levels of inflammatory markers, tight junction proteins, and neurotransmitters determined using Western Blots. After 4-weeks, brain levels of v-rel reticuloendotheliosis viral oncogene homolog A (avian) (RelA; NF-kB subunit), IkB kinase (IKK), and glial fibrillary acidic protein (GFAP) were significantly elevated; differences in zonula occludens-1 (ZO-1), claudin-5, glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were not significant. In retina, significant differences were observed only for TH (decreased), Rel A (increased), and GFAP (increased) levels. Glucose-specific differences in initial choice latency and discrimination ratios were also observed. After 8-weeks, RelA, GAD, and TH were significantly elevated in both tissues; IKK and GFAP levels were also elevated, though not significantly. ZO-1 and claudin-5 levels osmotically decreased in retina but displayed an increasing trend in glucose-treated brains. Differences in discrimination ratio were driven by osmotic load. OMRs increased in glucose-treated fish at both ages. In vivo analysis of retinal vasculature suggested thicker vessels after 4-weeks, but thinner vessels at 8-weeks. In vitro, glucose treatment reduced formation of nodes and meshes in 3B-11 endothelial cells, suggesting a reduced ability to form a vascular network. Overall, hyperglycemia triggered a strong inflammatory response causing initial trending changes in tight junction and neuronal markers. Most differences after 4-weeks of exposure were observed in glucose-treated fish suggesting effects on glucose metabolism independent of osmotic load. After 8-weeks, the inflammatory response remained and glucose-specific effects on neurotransmitter markers were observed. Osmotic differences impacted cognitive behavior and retinal protein levels; protein levels in brain displayed glucose-driven changes. Thus, we not only observed differential sensitivities of retina and brain to glucose-insult, but also different cellular responses, suggesting hyperglycemia causes complex effects at the cellular level and/or that zebrafish are able to compensate for the continued high blood glucose levels.

Deciphering the Interdependent Labyrinth between Gut Microbiota and the Immune System

The human gut microbiome interacts with each other and the host, which has significant effects on health and disease development. Intestinal homeostasis and inflammation are maintained by the dynamic interactions between gut microbiota and the innate and adaptive immune systems. Numerous metabolic products produced by the gut microbiota play a role in mediating cross-talk between gut epithelial and immune cells. In the event of an imbalance between the immune system and microbiota, the body becomes susceptible to infections, and homeostasis is compromised. This review mainly focuses on the interplay between microbes and the immune system, such as, T-cell and B-cell mediated adaptive responses to microbiota and signaling pathways for effective communication between the two. We have also highlighted the role of microbes in the activation of the immune response, the development of memory cells, and how the immune system determines the diversity of human gut microbiota. The review also explains the relationship of commensal microbiota and their relation in the production of immunoglobulins.

FI: The Fecobiome Initiative

Animal husbandry has been key to the sustainability of human societies for millennia. Livestock animals, such as cattle, convert plants to protein biomass due to a compartmentalized gastrointestinal tract (GIT) and the complementary contributions of a diverse GIT microbiota, thereby providing humans with meat and dairy products. Research on cattle gut microbial symbionts has mainly focused on the rumen (which is the primary fermentation compartment) and there is a paucity of functional insight on the intestinal (distal end) microbiota, where most foodborne zoonotic bacteria reside. Here, we present the Fecobiome Initiative (or FI), an international effort that aims at facilitating collaboration on research projects related to the intestinal microbiota, disseminating research results, and increasing public availability of resources. By doing so, the FI can help mitigate foodborne and animal pathogens that threaten livestock and human health, reduce the emergence and spread of antimicrobial resistance in cattle and their proximate environment, and potentially improve the welfare and nutrition of animals. We invite all researchers interested in this type of research to join the FI through our website: www.fecobiome.com

Effects of a Mediterranean diet on the development of diabetic complications: A longitudinal study from the nationwide diabetes report of the National Program for Prevention and Control of Diabetes (NPPCD 2016-2020)

OBJECTIVE

To evaluate the effectiveness of a Mediterranean dietary pattern on the incidence of macrovascular and microvascular complications of diabetes, namely cardiovascular disease (CVD), diabetic foot disorders, diabetic retinopathy, nephropathy, and neuropathy.

METHODS

This longitudinal study was conducted among 71392 adults with diabetes who attended academic tertiary-care outpatient clinics from February 2016 to March 2020 across Iran using the National Program for Prevention and Control of Diabetes database. Among them, 22187 patients with diabetes (type 1 and type 2) completed 2-11 follow-up visits after baseline registration. The association between adherence to a Mediterranean diet and diabetic complications was assessed using pooled logistic regression models. This association was adjusted for potential confounders. The effect of time was assessed using fractional polynomials.

RESULTS

A total of 22187 participants were included in the analysis (30.22% men and 69.78% women) with either type 1 (mean age 50.7 years) or type 2 (mean age 59.9 years) diabetes. After adjustment for confounding variables, there was a negative correlation between adherence to a Mediterranean diet and the incidence of CVD among patients with type 1 diabetes (T1D) and 2 diabetes (T2D) (OR= 0.53, 95% CI: 0.37 - 0.75, p-value <0.001 and OR= 0.61, 95% CI: 0.57 - 0.89, p-value <0.001, respectively). Also, the diet had a statistically significant protective effect against incident symptomatic neuropathy (OR= 0.32, 95% CI: 0.23 - 0.43, p-value <0.001, and OR= 0.68, 95% CI: 0.64 - 0.72, p-value <0.001, respectively), nephropathy (OR= 0.42, 95% CI: 0.30 - 0.58, p-value <0.001, and OR= 0.88, 95% CI: 0.80 - 0.96, p-value= 0.007, respectively), and retinopathy (OR= 0.32, 95% CI: 0.24 - 0.44, p-value <0.001, and OR= 0.68, 95% CI: 0.61 - 0.71, p-value <0.001, respectively) in T1D and T2D.

CONCLUSION

The Mediterranean dietary pattern is associated with a lower incidence of CVD and microvascular complications (i.e. diabetic retinopathy, nephropathy, and neuropathy) among a cohort of patients with T1D and T2D in Iran.

Polymerization-Mediated Multifunctionalization of Living Cells for Enhanced Cell-Based Therapy

Surface decoration of living cells by exogenous substances offers a unique tool for understanding and tuning cell behaviors, which plays a critical role in cell-based therapy. Here, a facile yet versatile approach for decorating individual living cells with multimodal coatings is reported. By simply co-depositing with dopamine under a cytocompatible condition, various functional small molecules and polymers can be encoded to form a multifunctional coating on a cell's surface. The accessibility and versatility of this method to decorate diverse cells, including bacteria, fungi, and mammalian cells is demonstrated. With the ability to tune surface functions, ligand co-deposited gut microbiota is prepared as oral therapeutics for targeted treatment of colitis. Given the dual cytoprotective and targeting effects of the coating, decorated cells show more than 30-times higher bioavailability in the gut and fourfold higher accumulation in the inflamed tissue in comparison with those of uncoated bacteria. Multimodal therapeutic cells further validate strikingly increased treatment efficacy over clinical aminosalicylic acid in colitis mice. Decorating with multifunctional coatings proposes a robust platform for developing multimodal cells for enhanced cell-based therapy.

New Studies of Pathogenesis of Rheumatoid Arthritis with Collagen-Induced and Collagen Antibody-Induced Arthritis Models: New Insight Involving Bacteria Flora

Much public research suggests that autoimmune diseases such as rheumatoid arthritis (RA) are induced by aberrant “self” immune responses attacking autologous tissues and organ components. However, recent studies have reported that autoimmune diseases may be triggered by dysbiotic composition changes of the intestinal bacteria and an imbalance between these bacteria and intestinal immune systems. However, there are a few solid concepts or methods to study the putative involvement and relationship of these inner environmental factors in RA pathogenesis. Fortunately, Collagen-Induced Arthritis (CIA) and Collagen Antibody-Induced Arthritis (CAIA) models have been widely used as animal models for studying the pathogenesis of RA. In addition to RA, these models can be extensively used as animal models for studying complicated hypotheses in many diseases. In this review, we introduce some basic information about the CIA and CAIA models as well as how to apply these models effectively to investigate relationships between the pathogenesis of autoimmune diseases, especially RA, and the dysbiosis of intestinal bacterial flora.

Arecanut (Areca catechu L.) Seed Polyphenol-Ameliorated Osteoporosis by Altering Gut Microbiome via LYZ and the Immune System in Estrogen-Deficient Rats

Polyphenol can improve osteoporosis and is closely associated with gut microbiota, while the mechanism and the relationship among polyphenol, osteoporosis, and gut microbiota colonization remain unclear. Here, an osteoporosis rat model established by ovariectomy was employed to investigate the improving mechanism of arecanut (Areca catechu L.) seed polyphenol (ACP) on osteoporosis by regulating gut microbiota. We analyzed the bone microstructure, Paneth cells, regulating microbial protein (lysozyme (LYZ)), proinflammatory cytokines, macrophage infiltration levels, and gut microbial communities in a rat. ACP improved the trabecular microstructure compared to OVX, including the increased trabecular number (Tb.N) (P < 0.01) and trabecular thickness (Tb.Th) (P < 0.001) and decreased trabecular separation (Tb.Sp) (P < 0.01). At the phylum level, Bacteroidetes was increased after ovariectomy (P < 0.001) and Firmicutes and Proteobacteria were increased in ACP (P < 0.001). Antiosteoporosis groups with lower LYZ and Paneth cells (P < 0.001) showed that the microbiota Alistipes, which have a negative effect on bone metabolism were decreased in ACP (P < 0.001). Altogether, these studies showed that the estrogen deficiency could induce the shedding of Paneth cells, which leads to the decrease of LYZ, while ACP could increase the LYZ expression by maintaining the population of Paneth cells in an estrogen-deficient host, which were implicated in gut microbiota regulation and improved osteoporosis by controlling the inflammatory reaction.

Quantitative Analysis and Visualization of the Interaction Between Intestinal Microbiota and Type 1 Diabetes in Children Based on Multi-Databases

Background: As an important autoimmune disease, type 1 diabetes (T1D) is often diagnosed in children, but due to the complexity of the etiology of diabetes and many other factors, the disease pathogenesis of diabetes is still unclear. The intestinal microbiota has been proved to have close relationships with T1D in recent years, which is one of the most important molecular bases of pathogenesis and prognosis factors for T1D. Using the multi-omics and multicenter sample analysis method, a number of intestinal microbiota in T1D have been discovered and explained, which has provided comprehensive and rich information. However, how to find more useful information and get an intuitive understanding that people need conveniently in the huge data sea has become the focus of attention. Therefore, quantitative analysis and visualization of the interaction between intestinal microbiota and T1D in children are urgently needed. Methods: We retrieved the detailed original data from the National Center for Biotechnology Information, GMREPO, and gutMEGA databases and other authoritative multiple projects with related research; the ranking of intestinal microbiota abundance from healthy people, overall T1D patients, and T1D in children (0-18 years old) were detailed analyzed, classified, and visualized. Results: A total of 515 bacterial species and 161 related genera were fully analyzed. Also, Prevotella copri was led by 21.25% average abundance, followed by Clostridium tertium of 10.39% in all-cross T1D patients. For children with T1D, Bacteroides vulgatus has high abundance in all age periods, whereas the abundance of each intestinal microbiota was more uniform in female samples, with the ranking from high to low as Bacteroides dorei 9.56%, P. copri 9.53%, Streptococcus pasteurianus 8.15%, and C. tertium 7.53%, whereas in male samples, P. copri was accounted for the largest by 22.72%. The interaction between intestinal microbiota and comparison between healthy people and children with T1D was also detailed analyzed. Conclusions: This study provides a new method and comprehensive perspectives for the evaluation of the interaction between intestinal microbiota and T1D in children. A set of useful information of intestinal microbiota with its internal interaction and connections has been presented, which could be a compact, immediate, and practical scientific reference for further molecular biological and clinical translational research of T1D in children.

Vaccine Interactions With the Infant Microbiome: Do They Define Health and Disease?

Over the past decade, there has been a growing awareness of the vital role of the microbiome in the function of the immune system. Recently, several studies have demonstrated a relationship between the composition of the microbiome and the vaccine-specific immune response. As a result of these findings, the administration of probiotics has been proposed as a means of boosting vaccine-specific immunity. Early results have so far been highly inconsistent, with little evidence of sustained benefit. To date, a precise determination of the aspects of the microbiome that impact immunity is still lacking, and the mechanisms of action are also unknown. Further investigations into these questions are necessary to effectively manipulate the microbiome for the purpose of boosting immunity and enhancing vaccine-specific responses in infants. In this review, we summarize recent studies aimed at altering the neonatal gut microbiome to enhance vaccine responses and highlight gaps in knowledge and understanding. We also discuss research strategies aimed at filling these gaps and developing potential therapeutic interventions.

Inflammaging in Endemic Areas for Infectious Diseases

Immunosenescence is marked by a systemic process named inflammaging along with a series of defects in the immunological activity that results in poor responses to infectious agents and to vaccination. Inflammaging, a state of low-grade chronic inflammation, usually leads to chronic inflammatory diseases and frailty in the elderly. However, some elderly escape from frailty and reach advanced age free of the consequences of inflammaging. This process has been called immunological remodeling, and it is the hallmark of healthy aging as described in the studies of centenarians in Italy. The biological markers of healthy aging are still a matter of debate, and the studies on the topic have focused on inflammatory versus remodeling processes and molecules. The sub-clinical inflammatory status associated with aging might be a deleterious event for populations living in countries where chronic infectious diseases are not prevalent. Nevertheless, in other parts of the world where they are, two possibilities may occur. Inflammatory responses may have a protective effect against these infectious agents. At the same time, the long-term consequences of protective immune responses during chronic infections may result in accelerated immunosenescence in these individuals. Therefore, the biological markers of healthy aging can vary according to environmental, cultural, and geographical settings that reflect worldwide, and in a non-biased, non-westernized perspective, the changes that we experience regarding our contacts with microorganisms and the outcomes of such contacts.

The Growing Epidemic of Diabetes Mellitus

BACKGROUND

During the past decades, the prevalence of diabetes (DM) has increased significantly, mainly as a result of continuous rise in the incidence of type 2 DM. According to World Health Organization statistics, >422 million adults globally were suffering from DM in 2014 and a continuous rise in DM prevalence is expected.

OBJECTIVE

The present review considers recent epidemiological data providing worldwide estimates regarding the incidence of DM.

METHODS

A comprehensive literature search was conducted to identify available data from epidemiological studies evaluating the current burden of DM.

RESULTS

Over the past few decades the prevalence of DM has risen significantly in nearly all countries and may be considered as a growing epidemic. Urbanization and income status are major factors which influence current rates in the prevalence studies introducing interesting differences between several population groups.

CONCLUSION

Having recognized the global burden of DM, we now realize the urgent need for effective interventions. In order to monitor the public-health strategies and design effective future interventions we need reliable global estimates regarding the prevalence of DM.

Heterogeneity of CD4+CD25+Foxp3+Treg TCR β CDR3 Repertoire Based on the Differences of Symbiotic Microorganisms in the Gut of Mice

Gut microbes play a crucial role in the occurrence and development of autoimmune diseases. The diversity of intestinal microorganisms affected by the living environment, regulate the immune function of peripheral immune organs and local tissues. In the study, the diversity of intestinal microorganisms of Germ-free (GF), Specific Pathogen-free (SPF), and Clean (CL) BALB/c mice were conducted by 16S rDNA sequencing. High-throughput sequencing technology was used to analysis the composition and characterization of TCR β chain CDR3 repertoires in Regulatory T cells (Treg) in intestine and spleen of GF, SPF, and CL mice, so as to investigate the effects of differential composition of intestinal microorganisms on the CD4⁺CD25⁺Foxp3⁺Treg TCR β CDR3 repertoire of intestine and spleen. We observed that GF, SPF, and CL mice have different gut microorganism composition, and the abundance and quantity of microorganisms are positively correlated with the level of feeding environment. Interestingly, incomplete structure of spleen and small intestine in GF mice was found. Moreover, a significant difference in the usage of high frequency unique CDR3 amino acid sequences was detected in the intestinal Treg TCRβ CDR3 repertoire among GF, SPF and CL mice, and there were a greater heterogeneity in the usage frequency of TRBV, TRBJ, and TRBV-TRBJ combinations gene segments. However, the effect of different feeding environment on the mice Treg TCRβ CDR3 repertoire of spleen was weak, implying that the different composition of intestinal microbiota may primarily affect the diversity of the local Treg TCRβ CDR3 repertoire and does not alter the overall properties of the circulating immune system. These results provide basic data to further analyze the mechanism of gut microbes regulating the intestinal mucosal immune system.

Intestinal Flora and Disease Mutually Shape the Regional Immune System in the Intestinal Tract

The intestinal tract is the largest digestive organ in the human body. It is colonized by, and consistently exposed to, a myriad of microorganisms, including bifidobacteria, lactobacillus, Escherichia coli, enterococcus, clostridium perfringens, and pseudomonas. To protect the body from potential pathogens, the intestinal tract has evolved regional immune characteristics. These characteristics are defined by its unique structure, function, and microenvironment, which differ drastically from those of the common central and peripheral immune organs. The intestinal microenvironment created by the intestinal flora and its products significantly affects the immune function of the region. In turn, specific diseases regulate and influence the composition of the intestinal flora. A constant interplay occurs between the intestinal flora and immune system. Further, the intestinal microenvironment can be reconstructed by probiotic use or microbiota transplantation, functioning to recalibrate the immune homeostasis, while also contributing to the treatment or amelioration of diseases. In this review, we summarize the relationship between the intestinal flora and the occurrence and development of diseases as an in-turn effect on intestinal immunity. We also discuss improved immune function as it relates to non-specific and specific immunity. Further, we discuss the proliferation, differentiation and secretion of immune cells, within the intestinal region following remodeling of the microenvironment as a means to ameliorate and treat diseases. Finally, we suggest strategies for improved utilization of intestinal flora.

Bacteroidetes and Firmicutes levels in gut microbiota and effects of hosts TLR2/TLR4 gene expression levels in adult type 1 diabetes patients in Istanbul, Turkey

AIM

The aim of this study was to determine and compare the levels of both Bacteroidetes and Firmicutes in the gut microbiota and TLR2/TLR4 gene expression in the blood of patients with type 1 diabetes mellitus (T1DM) and healthy individuals. These results may serve as a preliminary assessment to guide future research.

METHOD

Between January and October 2014, stool and blood samples were collected from 53 adult T1DM patients and 53 age- and gender-matched healthy individuals. Bacteroidetes and Firmicutes levels were assessed from stool sample DNA and TLR2 and TLR4 expression levels were analyzed via qPCR using RNA from EDTA blood samples from both patients and healthy controls.

RESULTS

The amounts of Bacteroidetes and Firmicutes were statistically significantly higher and lower, respectively, in the T1DM group than in the healthy control group (p < 0.001 and p < 0.001, respectively). In addition, the Firmicutes/Bacteroidetes ratios in patients with T1DM were significantly lower than in healthy controls. The TLR4 and TLR2 gene expression levels in T1DM patients were significantly upregulated and downregulated, respectively, compared to those in the control group.

CONCLUSION

Our data are the first to show a relationship between T1DM and gut microbiota in our country. In addition, our results provide information about the connections between T1DM, gut microbiota, and TLR2 and TLR4 expression. We believe that Bacteroidetes and Firmicutes in the gut microbiota may play a role in the autoimmune process of T1DM and that these findings should be further investigated in the future.

Rat Models of Human Type 1 Diabetes

Rat models of human type 1 diabetes have been shown to be of great importance for the elucidation of the mechanisms underlying the development of autoimmune diabetes. The three major well-established spontaneous rat models are the BioBreeding (BB) diabetes-prone rat, the Komeda diabetes-prone (KDP) rat, and the IDDM (LEW.1AR1-iddm) rat. Their distinctive features are described with special reference to their pathology, immunology, and genetics and compared with the situation in patients with type 1 diabetes mellitus. For all three established rat models, a distinctive genetic mutation has been identified that is responsible for the manifestation of the diabetic syndrome in these rat strains.

Gut microbiome in type 1 diabetes: A comprehensive review

Type 1 diabetes (T1D) is an autoimmune disease, which is characterized by the destruction of islet β cells in the pancreas triggered by genetic and environmental factors. In past decades, extensive familial and genome-wide association studies have revealed more than 50 risk loci in the genome. However, genetic susceptibility cannot explain the increased incidence of T1D worldwide, which is very likely attributed by the growing impact of environmental factors, especially gut microbiome. Recently, the role of gut microbiome in the pathogenesis of T1D has been uncovered by the increasing evidence from both human subjects and animal models, strongly indicating that gut microbiome might be a pivotal hub of T1D-triggering factors, especially environmental factors. In this review, we summarize the current aetiological and mechanism studies of gut microbiome in T1D. A better understanding of the role of gut microbiome in T1D may provide us with powerful prognostic and therapeutic tools in the near future.

Intestinal Dysbiosis in Autoimmune Diabetes Is Correlated With Poor Glycemic Control and Increased Interleukin-6: A Pilot Study

Intestinal dysbiosis associated with immunological deregulation, leaky gut, bacterial translocation, and systemic inflammation has been associated with autoimmune diseases, such as type 1 diabetes (T1D). The aim of this study was to investigate the intestinal dysbiosis in T1D patients and correlate these results with clinical parameters and cytokines. The present study was approved by the Barretos Cancer Hospital (Process number 903/2014), and all participants have signed the informed consent in accordance with the Declaration of Helsinki, and answered a questionnaire about dietary habits. Stool samples were used for bacterial 16S sequencing by MiSeq Illumina platform. IL-2, IL-4, IL-6, IL-10, IL-17A, TNF, and IFN-γ plasma concentrations were determined by cytometric bead arrays. The Pearson’s chi-square, Mann–Whitney and Spearman correlation were used for statistical analyses. Alpha and beta diversities were conducted by using an annotated observed taxonomic units table. This study included 20 patients and 28 controls, and we found significant differences (P < 0.05) among consumption of vegetables, proteins, milk and derivatives, spicy food, and canned food when we compare patients and controls. We detected intestinal dysbiosis in T1D patients when we performed the beta diversity analysis (P = 0.01). The prevalent species found in patients’ stool were the Gram-negatives Bacteroides vulgatus, Bacteroides rodentium, Prevotella copri, and Bacteroides xylanisolvens. The inflammatory interleukin-6 was significantly increased (P = 0.017) in patients’ plasma. Furthermore, we showed correlation among patients with poor glycemic control, represented by high levels of HbA1_C percentages and Bacteroidetes, Lactobacillales, and Bacteroides dorei relative abundances. We concluded that there are different gut microbiota profiles between T1D patients and healthy controls. The prevalent Gram-negative species in T1D patients could be involved in the leaky gut, bacterial translocation, and poor glycemic control. However, additional studies, with larger cohorts, are required to determine a “signature” of the intestinal microbiota in T1D patients in the Brazilian population.

Intestinal barrier and gut microbiota: Shaping our immune responses throughout life

The gastrointestinal (GI) tract is considered the largest immunological organ in the body having a central role in regulating immune homeostasis. Contrary to earlier belief, the intestinal epithelial barrier is not a static physical barrier but rather strongly interacts with the gut microbiome and cells of the immune system. This intense communication between epithelial cells, immune cells and microbiome will shape specific immune responses to antigens, balancing tolerance and effector immune functions. Recent studies indicate that composition of the gut microbiome affects immune system development and modulates immune mediators, which in turn affect the intestinal barrier. Moreover, dysbiosis may favor intestinal barrier disruption and could be related to increased susceptibility to certain diseases. This review will be focused on the development of the intestinal barrier and its function in host immune defense and how gut microbiome composition throughout life can affect this role.

Advanced glycation end products dietary restriction effects on bacterial gut microbiota in peritoneal dialysis patients; a randomized open label controlled trial

The modern Western diet is rich in advanced glycation end products (AGEs). We have previously shown an association between dietary AGEs and markers of inflammation and oxidative stress in a population of end stage renal disease (ESRD) patients undergoing peritoneal dialysis (PD). In the current pilot study we explored the effects of dietary AGEs on the gut bacterial microbiota composition in similar patients. AGEs play an important role in the development and progression of cardiovascular (CVD) disease. Plasma concentrations of different bacterial products have been shown to predict the risk of incident major adverse CVD events independently of traditional CVD risk factors, and experimental animal models indicates a possible role AGEs might have on the gut microbiota population. In this pilot randomized open label controlled trial, twenty PD patients habitually consuming a high AGE diet were recruited and randomized into either continuing the same diet (HAGE, n = 10) or a one-month dietary AGE restriction (LAGE, n = 10). Blood and stool samples were collected at baseline and after intervention. Variable regions V3-V4 of 16s rDNA were sequenced and taxa was identified on the phyla, genus, and species levels. Dietary AGE restriction resulted in a significant decrease in serum N^ε-(carboxymethyl) lysine (CML) and methylglyoxal-derivatives (MG). At baseline, our total cohort exhibited a lower relative abundance of Bacteroides and Alistipes genus and a higher abundance of Prevotella genus when compared to the published data of healthy population. Dietary AGE restriction altered the bacterial gut microbiota with a significant reduction in Prevotella copri and Bifidobacterium animalis relative abundance and increased Alistipes indistinctus, Clostridium citroniae, Clostridium hathewayi, and Ruminococcus gauvreauii relative abundance. We show in this pilot study significant microbiota differences in peritoneal dialysis patients’ population, as well as the effects of dietary AGEs on gut microbiota, which might play a role in the increased cardiovascular events in this population and warrants further studies.

Intestinal dysbiosis and probiotic applications in autoimmune diseases

In humans, a complex interaction between the host immune system and commensal microbiota is required to maintain gut homeostasis. In this symbiotic relationship, the microbiota provides carbohydrate fermentation and digestion, vitamin synthesis and gut-associated lymphoid tissue development, as well as preventing colonization by pathobionts, whereas the host offers a niche and nutrients for the survival of the microbiota. However, when this mutualistic relationship is compromised and an altered interaction between immune cells and microorganisms occurs, the gut microbiota may cause or contribute to the establishment of infectious diseases and trigger autoimmune diseases. Researchers have made efforts to clarify the role of the microbiota in autoimmune disease development and find new therapeutic approaches to treat immune-mediated diseases. However, the exact mechanisms involved in the dysbiosis and breakdown of the gut epithelial barrier are currently unknown. Here, we provide a general overview of studies describing gut microbiota perturbations in animal models of autoimmune diseases, such as type 1 diabetes, multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosus. Moreover, we include the main studies concerning dysbiosis in humans and a critical discussion of the existing data on the use of probiotics in these autoimmune diseases.

Intestinal dysbiosis and probiotic applications in autoimmune diseases

In humans, a complex interaction between the host immune system and commensal microbiota is required to maintain gut homeostasis. In this symbiotic relationship, the microbiota provides carbohydrate fermentation and digestion, vitamin synthesis and gut-associated lymphoid tissue development, as well as preventing colonization by pathobionts, whereas the host offers a niche and nutrients for the survival of the microbiota. However, when this mutualistic relationship is compromised and an altered interaction between immune cells and microorganisms occurs, the gut microbiota may cause or contribute to the establishment of infectious diseases and trigger autoimmune diseases. Researchers have made efforts to clarify the role of the microbiota in autoimmune disease development and find new therapeutic approaches to treat immune-mediated diseases. However, the exact mechanisms involved in the dysbiosis and breakdown of the gut epithelial barrier are currently unknown. Here, we provide a general overview of studies describing gut microbiota perturbations in animal models of autoimmune diseases, such as type 1 diabetes, multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosus. Moreover, we include the main studies concerning dysbiosis in humans and a critical discussion of the existing data on the use of probiotics in these autoimmune diseases.

Role of intestinal microbiota and metabolites on gut homeostasis and human diseases

Background

A vast diversity of microbes colonizes in the human gastrointestinal tract, referred to intestinal microbiota. Microbiota and products thereof are indispensable for shaping the development and function of host innate immune system, thereby exerting multifaceted impacts in gut health.

Methods

This paper reviews the effects on immunity of gut microbe-derived nucleic acids, and gut microbial metabolites, as well as the involvement of commensals in the gut homeostasis. We focus on the recent findings with an intention to illuminate the mechanisms by which the microbiota and products thereof are interacting with host immunity, as well as to scrutinize imbalanced gut microbiota (dysbiosis) which lead to autoimmune disorders including inflammatory bowel disease (IBD), Type 1 diabetes (T1D) and systemic immune syndromes such as rheumatoid arthritis (RA).

Results

In addition to their well-recognized benefits in the gut such as occupation of ecological niches and competition with pathogens, commensal bacteria have been shown to strengthen the gut barrier and to exert immunomodulatory actions within the gut and beyond. It has been realized that impaired intestinal microbiota not only contribute to gut diseases but also are inextricably linked to metabolic disorders and even brain dysfunction.

Conclusions

A better understanding of the mutual interactions of the microbiota and host immune system, would shed light on our endeavors of disease prevention and broaden the path to our discovery of immune intervention targets for disease treatment.

The role of Gut Microbiota in the development of obesity and Diabetes

Obesity and its associated complications like type 2 diabetes (T2D) are reaching epidemic stages. Increased food intake and lack of exercise are two main contributing factors. Recent work has been highlighting an increasingly more important role of gut microbiota in metabolic disorders. It’s well known that gut microbiota plays a major role in the development of food absorption and low grade inflammation, two key processes in obesity and diabetes. This review summarizes key discoveries during the past decade that established the role of gut microbiota in the development of obesity and diabetes. It will look at the role of key metabolites mainly the short chain fatty acids (SCFA) that are produced by gut microbiota and how they impact key metabolic pathways such as insulin signalling, incretin production as well as inflammation. It will further look at the possible ways to harness the beneficial aspects of the gut microbiota to combat these metabolic disorders and reduce their impact.

Gut microbiota, obesity and diabetes

The central role of the intestinal microbiota in the progression and, equally, prevention of metabolic dysfunction is becoming abundantly apparent. The symbiotic relationship between intestinal microbiota and host ensures appropriate development of the metabolic system in humans. However, disturbances in composition and, in turn, functionality of the intestinal microbiota can disrupt gut barrier function, a trip switch for metabolic endotoxemia. This low-grade chronic inflammation, brought about by the influx of inflammatory bacterial fragments into circulation through a malfunctioning gut barrier, has considerable knock-on effects for host adiposity and insulin resistance. Conversely, recent evidence suggests that there are certain bacterial species that may interact with host metabolism through metabolite-mediated stimulation of enteric hormones and other systems outside of the gastrointestinal tract, such as the endocannabinoid system. When the abundance of these keystone species begins to decline, we see a collapse of the symbiosis, reflected in a deterioration of host metabolic health. This review will investigate the intricate axis between the microbiota and host metabolism, while also addressing the promising and novel field of probiotics as metabolic therapies.

Pancreatic Beta Cell Survival and Signaling Pathways: Effects of Type 1 Diabetes-Associated Genetic Variants

Type 1 diabetes (T1D) is a complex autoimmune disease in which pancreatic beta cells are specifically destroyed by the immune system. The disease has an important genetic component and more than 50 loci across the genome have been associated with risk of developing T1D. The molecular mechanisms by which these putative T1D candidate genes modulate disease risk, however, remain poorly characterized and little is known about their effects in pancreatic beta cells. Functional studies in in vitro models of pancreatic beta cells, based on techniques to inhibit or overexpress T1D candidate genes, allow the functional characterization of several T1D candidate genes. This requires a multistage procedure comprising two major steps, namely accurate selection of genes of potential interest and then in vitro and/or in vivo mechanistic approaches to characterize their role in pancreatic beta cell dysfunction and death in T1D. This chapter details the methods and settings used by our groups to characterize the role of T1D candidate genes on pancreatic beta cell survival and signaling pathways, with particular focus on potentially relevant pathways in the pathogenesis of T1D, i.e., inflammation and innate immune responses, apoptosis, beta cell metabolism and function.

Association of Early Exposure of Probiotics and Islet Autoimmunity in the TEDDY Study

IMPORTANCE

Probiotics have been hypothesized to affect immunologic responses to environmental exposures by supporting healthy gut microbiota and could therefore theoretically be used to prevent the development of type 1 diabetes mellitus (T1DM)-associated islet autoimmunity.

OBJECTIVE

To examine the association between supplemental probiotic use during the first year of life and islet autoimmunity among children at increased genetic risk of T1DM.

DESIGN, SETTING, AND PARTICIPANTS

In this ongoing prospective cohort study that started September 1, 2004, children from 6 clinical centers, 3 in the United States (Colorado, Georgia/Florida, and Washington) and 3 in Europe (Finland, Germany, and Sweden), were followed up for T1DM-related autoantibodies. Blood samples were collected every 3 months between 3 and 48 months of age and every 6 months thereafter to determine persistent islet autoimmunity. Details of infant feeding, including probiotic supplementation and infant formula use, were monitored from birth using questionnaires and diaries. We applied time-to-event analysis to study the association between probiotic use and islet autoimmunity, stratifying by country and adjusting for family history of type 1 diabetes, HLA-DR-DQ genotypes, sex, birth order, mode of delivery, exclusive breastfeeding, birth year, child's antibiotic use, and diarrheal history, as well as maternal age, probiotic use, and smoking. Altogether 8676 infants with an eligible genotype were enrolled in the follow-up study before the age of 4 months. The final sample consisted of 7473 children with the age range of 4 to 10 years (as of October 31, 2014).

EXPOSURES

Early intake of probiotics.

MAIN OUTCOMES AND MEASURES

Islet autoimmunity revealed by specific islet autoantibodies.

RESULTS

Early probiotic supplementation (at the age of 0-27 days) was associated with a decreased risk of islet autoimmunity when compared with probiotic supplementation after 27 days or no probiotic supplementation (hazard ratio [HR], 0.66; 95% CI, 0.46-0.94). The association was accounted for by children with the DR3/4 genotype (HR, 0.40; 95% CI, 0.21-0.74) and was absent among other genotypes (HR, 0.97; 95% CI, 0.62-1.54).

CONCLUSIONS AND RELEVANCE

Early probiotic supplementation may reduce the risk of islet autoimmunity in children at the highest genetic risk of T1DM. The result needs to be confirmed in further studies before any recommendation of probiotics use is made.

IMPLICATION OF GUT MICROBIOTA IN DIABETES MELLITUS AND OBESITY

Background and aims

Differences in the composition of the species of microorganisms in the gut may predict the evolution toward obesity and diabetes mellitus. We carried out a systematic review of the studies dedicated to the role of gut microbiota in diabetes mellitus and obesity.

Methods

A systematic literature search of electronic databases was performed, using the search syntax: "Gut microbiota and diabetes and obesity"; abstracts in English, with data about mechanisms of pathogenesis and treatment options by changing the gut composition were included (259 articles). Studies were excluded if they did not have an abstract, or they contained no data about the exact implication mechanism of microbiota.

Results

There are differences regarding the composition of the gut microbiota in healthy people and type 2 diabetes mellitus patients; the later proved to have significantly decreased Clostridium components, and increased Lactobacillus and Bifidobacterium populations.The intestines of obese subjects are less rich in microbial genes, have a reduced amount of Bacteroidetes and an increased amount of Firmicutes. Fecal microbiota transplantation from obese subjects resulted in adoption of the donor somatotype. Early differences in gut microbiota composition (higher number of Bifidobacteria) function as diagnostic markers for the development of type 2 diabetes mellitus in high-risk patients.The gut endotoxins contribute to metabolic syndrome manifestation. Experimental studies with prebiotic showed lower levels of cytokines and antiobesity potential.

Conclusion

Microbiota composition and its changes since childhood have an important role in the metabolic syndrome. Any intervention in order to prevent or treat obesity and diabetes mellitus should have as target the gut immune system.

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.

Role of the gastrointestinal ecosystem in the development of type 1 diabetes

A new emphasis has been put on the role of the gastrointestinal (GI) ecosystem in autoimmune diseases; however, there is limited knowledge about its role in type 1 diabetes (T1D). Distinct differences have been observed in intestinal permeability, epithelial barrier function, commensal microbiota, and mucosal innate and adaptive immunity of patients and animals with T1D, when compared with healthy controls. The non-obese diabetic (NOD) mouse and the BioBreeding diabetes prone (BBdp) rat are the most commonly used models to study T1D pathogenesis. With the increasing awareness of the importance of the GI ecosystem in systemic disease, it is critical to understand the basics, as well as the similarities and differences between rat and mouse models and human patients. This review examines the current knowledge of the role of the GI ecosystem in T1D and indicates the extensive opportunities for further investigation that could lead to biomarkers and therapeutic interventions for disease prevention and/or modulation.

Bacterial Flora Changes in Conjunctiva of Rats with Streptozotocin-Induced Type I Diabetes

Background

The microbiota of both humans and animals plays an important role in their health and the development of disease. Therefore, the bacterial flora of the conjunctiva may also be associated with some diseases. However, there are no reports on the alteration of bacterial flora in conjunctiva of diabetic rats in the literature. Therefore, we investigated the changes in bacterial flora in bulbar conjunctiva of rats with streptozotocin (STZ)-induced type I diabetes.

Methods

A high dose of STZ (60 mg/kg, i.p.) was injected into Sprague-Dawley (SD) rats to induce type I diabetes mellitus (T1DM). The diabetic rats were raised in the animal laboratory and at 8 months post-injection of STZ swab samples were taken from the bulbar conjunctiva for cultivation of aerobic bacteria. The bacterial isolates were identified by Gram staining and biochemical features. The identified bacteria from both diabetic and healthy rats were then compared.

Results

The diabetic and healthy rats had different bacterial flora present in their bulbar conjunctiva. In total, 10 and 8 bacterial species were found in the STZ and control groups, respectively, with only three species (Enterococcus faecium, Enterococcus gallinarum and Escherichia coli) shared between the two groups. Gram-positive bacteria were common in both groups and the most abundant was Enterococcus faecium. However, after the development of T1DM, the bacterial flora in the rat bulbar conjunctiva changed considerably, with a reduced complexity evident.

Conclusions

STZ-induced diabetes caused alterations of bacterial flora in the bulbar conjunctiva in rats, with some bacterial species disappearing and others emerging. Our results indicate that the conjunctival bacterial flora in diabetic humans should be surveyed for potential diagnostic markers or countermeasures to prevent eye infections in T1DM patients.

Impacts of gut bacteria on human health and diseases

Gut bacteria are an important component of the microbiota ecosystem in the human gut, which is colonized by 10¹⁴ microbes, ten times more than the human cells. Gut bacteria play an important role in human health, such as supplying essential nutrients, synthesizing vitamin K, aiding in the digestion of cellulose, and promoting angiogenesis and enteric nerve function. However, they can also be potentially harmful due to the change of their composition when the gut ecosystem undergoes abnormal changes in the light of the use of antibiotics, illness, stress, aging, bad dietary habits, and lifestyle. Dysbiosis of the gut bacteria communities can cause many chronic diseases, such as inflammatory bowel disease, obesity, cancer, and autism. This review summarizes and discusses the roles and potential mechanisms of gut bacteria in human health and diseases.

Microbial endocrinology: the interplay between the microbiota and the endocrine system

The new field of microbiome research studies the microbes within multicellular hosts and the many effects of these microbes on the host's health and well-being. We now know that microbes influence metabolism, immunity and even behavior. Essential questions, which are just starting to be answered, are what are the mechanisms by which these bacteria affect specific host characteristics. One important but understudied mechanism appears to involve hormones. Although the precise pathways of microbiota-hormonal signaling have not yet been deciphered, specific changes in hormone levels correlate with the presence of the gut microbiota. The microbiota produces and secretes hormones, responds to host hormones and regulates expression levels of host hormones. Here, we summarize the links between the endocrine system and the gut microbiota. We categorize these interactions by the different functions of the hormones, including those affecting behavior, sexual attraction, appetite and metabolism, gender and immunity. Future research in this area will reveal additional connections, and elucidate the pathways and consequences of bacterial interactions with the host endocrine system.

The intestinal microbiota: its role in health and disease

The intestinal microbiota (previously referred to as "intestinal flora") has entered the focus of research interest not only in microbiology but also in medicine. Huge progress has been made with respect to the analysis of composition and functions of the human microbiota. An "imbalance" of the microbiota, frequently also called a "dysbiosis," has been associated with different diseases in recent years. Crohn's disease and ulcerative colitis as two major forms of inflammatory bowel disease, irritable bowel syndrome (IBS) and some infectious intestinal diseases such as Clostridium difficile colitis feature a dysbiosis of the intestinal flora. Whereas this is somehow expected or less surprising, an imbalance of the microbiota or an enrichment of specific bacterial strains in the flora has been associated with an increasing number of other diseases such as diabetes, metabolic syndrome, non-alcoholic fatty liver disease or steatohepatitis and even psychiatric disorders such as depression or multiple sclerosis. It is important to understand the different aspects of potential contributions of the microbiota to pathophysiology of the mentioned diseases.

CONCLUSION

With the present manuscript, we aim to summarize the current knowledge and provide an overview of the different concepts on how bacteria contribute to health and disease in animal models and-more importantly-humans. In addition, it has to be borne in mind that we are only at the very beginning to understand the complex mechanisms of host-microbial interactions.

Does the microbiota play a role in the pathogenesis of autoimmune diseases?

The microbiota of the human metaorganism is not a mere bystander. These microbes have coevolved with us and are pivotal to normal development and homoeostasis. Dysbiosis of the GI microbiota is associated with many disease susceptibilities, including obesity, malignancy, liver disease and GI pathology such as IBD. It is clear that there is direct and indirect crosstalk between this microbial community and host immune response. However, the precise mechanism of this microbial influence in disease pathogenesis remains elusive and is now a major research focus. There is emerging literature on the role of the microbiota in the pathogenesis of autoimmune disease, with clear and increasing evidence that changes in the microbiota are associated with some of these diseases. Examples include type 1 diabetes, coeliac disease and rheumatoid arthritis, and these contribute significantly to global morbidity and mortality. Understanding the role of the microbiota in autoimmune diseases may offer novel insight into factors that initiate and drive disease progression, stratify patient risk for complications and ultimately deliver new therapeutic strategies. This review summarises the current status on the role of the microbiota in autoimmune diseases.

Reduced morbidity at diagnosis and improved glycemic control in children previously enrolled in DiPiS follow-up

AIMS/HYPOTHESIS

Children participating in longitudinal type 1 diabetes prediction studies were reported to have less severe disease at diabetes diagnosis. Our aim was to investigate children who from birth participated in the Diabetes Prediction in Skåne (DiPiS) study for metabolic status at diagnosis and then continued to be followed for 2 yr of regular clinical care.

METHODS

Children, followed in DiPiS before diagnosis, were compared to children in the same birth cohort, who did not participate in follow-up. Metabolic status, symptoms at diagnosis as well as hemoglobin A1c (HbA1c) and doses of insulin at 3, 6, 12, and 24 months after diagnosis were compared.

RESULTS

Children, followed in DiPiS and diagnosed at 2-12 yr of age, had 0.8% (9 mmol/mol) lower HbA1c at diagnosis than those who were not followed (p = 0.006). At diagnosis, fewer DiPiS children had symptoms (p = 0.014) and ketoacidosis at diagnosis were reduced (2% compared to 18%, p = 0.005). During regular clinical care, HbA1c levels for the DiPiS children remained lower both at 12 (0.4% (4 mmol/mol); p = 0.009) and 24 months (0.8% (9 mmol/mol) p  <  0.001) after diagnosis, despite no difference in total daily insulin between the two groups.

CONCLUSIONS

Participation in prospective follow-up before diagnosis of type 1 diabetes leads to earlier diagnosis with fewer symptoms, decreased incidence of ketoacidosis as well as better metabolic control up to 2 yr after diagnosis. Our data indicate that metabolic control at the time of diabetes diagnosis is important for early metabolic control possibly affecting the risk of long-term complications.

Influence of host immunoregulatory genes, ER stress and gut microbiota on the shared pathogenesis of inflammatory bowel disease and Type 1 diabetes

Inflammatory bowel disease (IBD) with its two distinct entities, Crohn's disease and ulcerative colitis, and Type 1 diabetes mellitus (T1D) are autoimmune diseases. The prevalence of these diseases continues to rapidly rise in the industrialized world. Despite the identification of several genetic loci that are associated with both IBD and T1D, thus far, there is a paucity of epidemiological data to support a clinical overlap. In an effort to better understand the underlying pathogenic mechanisms of both IBD and T1D, this review summarizes the literature about these related autoimmune diseases, describes the most recent advances in their etiopathogenesis and emphasizes the genetic and nongenetic factors that exercise a differential influence. Genome-wide association studies have identified genetic loci with a role in immune response regulation that are linked to both IBD (particularly Crohn's disease) and T1D. Some of these genetic loci (e.g., IL-18RAP) have a divergent role, conferring risk for one disease and protection for the other. Recent evidence highlights an important role of gut microbiota and cellular responses (e.g., endoplasmic reticulum stress) in the pathogenesis of both IBD and T1D.

Consumption of acidic water alters the gut microbiome and decreases the risk of diabetes in NOD mice

Infant formula and breastfeeding are environmental factors that influence the incidence of Type 1 Diabetes (T1D) as well as the acidity of newborn diets. To determine if altering the intestinal microbiome is one mechanism through which an acidic liquid plays a role in T1D, we placed non-obese diabetic (NOD)/ShiLtJt mice on neutral (N) or acidified H2O and monitored the impact on microbial composition and diabetes incidence. NOD-N mice showed an increased development of diabetes, while exhibiting a decrease in Firmicutes and an increase in Bacteroidetes, Actinobacteria, and Proteobacteria from as early as 2 weeks of age. NOD-N mice had a decrease in the levels of Foxp3 expression in CD4(+)Foxp3(+) cells, as well as decreased CD4(+)IL17(+) cells, and a lower ratio of IL17/IFNγ CD4+ T-cells. Our data clearly indicates that a change in the acidity of liquids consumed dramatically alters the intestinal microbiome, the presence of protective Th17 and Treg cells, and the incidence of diabetes. This data suggests that early dietary manipulation of intestinal microbiota may be a novel mechanism to delay T1D onset in genetically pre-disposed individuals.

pH of drinking water influences the composition of gut microbiome and type 1 diabetes incidence

Nonobese diabetic (NOD) mice spontaneously develop type 1 diabetes (T1D), progression of which is similar to that in humans, and therefore are widely used as a model for understanding the immunological basis of this disease. The incidence of T1D in NOD mice is influenced by the degree of cleanliness of the mouse colony and the gut microflora. In this report, we show that the T1D incidence and rate of disease progression are profoundly influenced by the pH of drinking water, which also affects the composition and diversity of commensal bacteria in the gut. Female NOD mice that were maintained on acidic pH water (AW) developed insulitis and hyperglycemia rapidly compared with those on neutral pH water (NW). Interestingly, forced dysbiosis by segmented filamentous bacteria (SFB)-positive fecal transfer significantly suppressed the insulitis and T1D incidence in mice that were on AW but not in those on NW. The 16S rDNA-targeted pyrosequencing revealed a significant change in the composition and diversity of gut flora when the pH of drinking water was altered. Importantly, autoantigen-specific T-cell frequencies in the periphery and proinflammatory cytokine response in the intestinal mucosa are significantly higher in AW-recipient mice compared with their NW counterparts. These observations suggest that pH of drinking water affects the composition of gut microflora, leading to an altered autoimmune response and T1D incidence in NOD mice.

Diabetes in Europe: an update

Diabetes is among the leading causes of death in the IDF Europe Region (EUR), continues to increase in prevalence with diabetic macro- and microvascular complications resulting in increased disability and enormous healthcare costs. In 2013, the number of people with diabetes is estimated to be 56 million in EUR with an overall estimated prevalence of 8.5%. However, estimates of diabetes prevalence in 2013 vary widely in the 56 diverse countries in EUR from 2.4% in Moldova to 14.9% in Turkey. Trends in diabetes prevalence also vary between countries with stable prevalence since 2002 for many countries but a doubling of diabetes prevalence in Turkey. For 2035, a further increase of nearly 10 million people with diabetes is projected for the EUR. Prevalence of type 1 has also increased over the past 20 years in EUR and there was estimated to be 129,350 cases in children aged 0-14 years in 2013. Registries provide valid information on incidence of type 1 diabetes with more complete data available for children than for adults. There are large differences in distribution of risk factors for diabetes at the population level in EUR. Modifiable risk factors such as obesity, physical inactivity, smoking behaviour (including secondhand smoking), environmental pollutants, psychosocial factors and socioeconomic deprivation could be tackled to reduce the incidence of type 2 diabetes in Europe. In addition, diabetes management is a major challenge to health services in the European countries. Improved networking practices of health professionals and other stakeholders in combination with empowerment of people with diabetes and continuous quality monitoring need to be further developed in Europe.

Modulation of virus-induced innate immunity and type 1 diabetes by IL-1 blockade

We used the LEW1.WR1 model of Kilham rat virus (KRV)-induced type 1 diabetes (T1D) to test the hypothesis that blocking IL-1 pathways early in the course of the disease can modulate virus-induced innate immunity and prevent disease progression. Administering KRV plus IL-1 receptor antagonist (Anakinra) for 14 d prevented insulitis and T1D. Anakinra reversed the KRV-induced systemic inflammation evidenced by the accumulation of T cells in the spleen and pancreatic lymph nodes on d 5 post-infection. Blocking IL-1 modulated the level of IRF-7 and IL-6 gene expression in the spleen and the p40 subunit of IL-12 and IL-23 in the serum. Anakinra did not interfere with the ability of LEW1.WR1 rats to clear the virus from the spleen, pancreatic lymph nodes or serum. Consistent with these data, normal levels of KRV-specific adaptive immune responses were detected in in the spleen and peripheral blood of the treated animals. Finally, blocking IL-1 pathways reversed the KRV-induced modulation of gut bacterial communities. The data may imply that IL-1 pathways are directly linked with early mechanisms whereby KRV infection leads to islet destruction, raising the hypothesis that blocking IL-1 pathways early in the course of the disease could be a useful therapeutic approach for disease prevention.