The crucial role of early-life gut microbiota in the development of type 1 diabetes

Can the Evidence-Based Use of Probiotics (Notably Saccharomyces boulardii CNCM I-745 and Lactobacillus rhamnosus GG) Mitigate the Clinical Effects of Antibiotic-Associated Dysbiosis?

Dysbiosis corresponds to the disruption of a formerly stable, functionally complete microbiota. In the gut, this imbalance can lead to adverse health outcomes in both the short and long terms, with a potential increase in the lifetime risks of various noncommunicable diseases and disorders such as atopy (like asthma), inflammatory bowel disease, neurological disorders, and even behavioural and psychological disorders. Although antibiotics are highly effective in reducing morbidity and mortality in infectious diseases, antibiotic-associated diarrhoea is a common, non-negligible clinical sign of gut dysbiosis (and the only visible one). Re-establishment of a normal (functional) gut microbiota is promoted by completion of the clinically indicated course of antibiotics, the removal of any other perturbing external factors, the passage of time (i.e. recovery through the microbiota's natural resilience), appropriate nutritional support, and-in selected cases-the addition of probiotics. Systematic reviews and meta-analyses of clinical trials have confirmed the strain-specific efficacy of some probiotics (notably the yeast Saccharomyces boulardii CNCM I-745 and the bacterium Lactobacillus rhamnosus GG) in the treatment and/or prevention of antibiotic-associated diarrhoea in children and in adults. Unusually for a probiotic, S. boulardii is a eukaryote and is not therefore directly affected by antibiotics-making it suitable for administration in cases of antibiotic-associated diarrhoea. A robust body of evidence from clinical trials and meta-analyses shows that the timely administration of an adequately dosed probiotic (upon initiation of antibiotic treatment or within 48 h) can help to prevent or resolve the consequences of antibiotic-associated dysbiosis (such as diarrhoea) and promote the resilience of the gut microbiota and a return to the pre-antibiotic state. A focus on the prescription of evidence-based, adequately dosed probiotics should help to limit unjustified and potentially ineffective self-medication.

Mutual modulation of gut microbiota and the immune system in type 1 diabetes models

The transgenic 116C-NOD mouse strain exhibits a prevalent Th17 phenotype, and reduced type 1 diabetes (T1D) compared to non-obese diabetic (NOD) mice. A cohousing experiment between both models revealed lower T1D incidence in NOD mice cohoused with 116C-NOD, associated with gut microbiota changes, reduced intestinal permeability, shifts in T and B cell subsets, and a transition from Th1 to Th17 responses. Distinct gut bacterial signatures were linked to T1D in each group. Using a RAG-2-/- genetic background, we found that T cell alterations promoted segmented filamentous bacteria proliferation in young NOD and 116C-NOD, as well as in immunodeficient NOD.RAG-2-/- and 116C-NOD.RAG-2-/- mice across all ages. Bifidobacterium colonization depended on lymphocytes and thrived in a non-diabetogenic environment. Additionally, 116C-NOD B cells in 116C-NOD.RAG-2-/- mice enriched the gut microbiota in Adlercreutzia and reduced intestinal permeability. Collectively, these results indicate reciprocal modulation between gut microbiota and the immune system in rodent T1D models.

Calcium-Sensitive Receptors Alters Intestinal Microbiota Metabolites Especially SCFAs and Ameliorates Intestinal Barrier Damage in Neonatal Rat Endotoxemia

Purpose

The calcium-sensing receptor (CaSR) acts as a major modulator of tissue responses related to calcium homeostasis and expresses highly in the mammalian intestine. Endotoxemia tends to impair intestinal barrier function and poses significant obstacles in clinical treatment. This work is designed to decipher whether CaSR can protect lipopolysaccharide (LPS)-induced intestinal barrier dysfunction in neonatal rats by targeting intestinal metabolites.

Patient and Methods

In this study, we utilized gas chromatography (GC) combined with liquid chromatography-mass spectrometry (LC-MS) to quantitatively analyze SCFAs and metabolites in fecal samples of 24 neonatal rats with LPS induced endotoxemia.

Results

Our results showed that CaSR alleviated endotoxin damage to the intestinal tight junction structure and upregulated the levels of butyric acid, propionic acid, valeric acid, and isovaleric acid in short-chain fatty acids (SCFAs). Non-targeted metabolomics analysis indicated that CaSR improved intestinal metabolic disorders by regulating glycerophospholipid metabolism, α-linolenic acid metabolism, as well as sphingolipids metabolism.

Conclusion

CaSR can alter intestinal microbiota metabolites, especially SCFAs, and improve intestinal barrier damage in neonatal rat endotoxemia.

Role of gut microbiota in the pathogenesis and treatment of diabetes mullites: Advanced research-based review

Gut microbiota plays an important role in the proper functioning of human organisms, while its dysbiosis is associated with disease in various body organs. Diabetes mellitus (DM) is a set of heterogeneous metabolic diseases characterized by hyperglycemia caused by direct or indirect insulin deficiency. There is growing evidence that gut microbiota dysbiosis is closely linked to the development of DM. Gut microbiota composition changes in type 1 diabetes mullites (T1DM) and type 2 diabetes mullites (T2DM) patients, which may cause gut leakiness and uncontrolled entry of antigens into the circulation system, triggering an immune response that damages the isle β cells or metabolic disorders. This review summarizes gut microbiota composition in healthy individuals and compares it to diabetes mullites patients. The possible pathogenesis by which gut microbiota dysbiosis causes DM, particularly gut leakiness and changes in gut microbiota metabolites is also discussed. It also presents the process of microbial-based therapies of DM.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring.

As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders.

Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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Maternal heminic vs. non-heminic iron intake differentially and persistently imprints the offspring's fecal microbiota.

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Males from heme-fed dams exhibit increased gut lumen reactive aldehydes in absence of direct dietary exposure to heme iron.

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Some of the increased reactive aldehydes closely covariated with Orders belonging to Bacteroidales and Lachnospirales.

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Maternal exposure to dietary heme iron impairs gut barrier and glucose tolerance in male offspring.

Gut microbiota differs in composition between adults with type 1 diabetes with or without depression and healthy control participants: a case-control study

Background

Individuals with type 1 diabetes and those with depression show differences in the composition of the gut microbiome from that of healthy people. However, these differences have not yet been studied in patients with both diseases. Therefore, we compared the gut microbiome of people with type 1 diabetes with or without depression with matched healthy controls.

Methods

A case-control study was conducted in 20 adults with type 1 diabetes (group A), 20 adults with type 1 diabetes and depression (group B), and 20 healthy adults (group C). Gut microbiota composition was determined by sequencing of the V3-V4 region of the bacterial 16S rDNA and alpha and beta diversity was compared between the groups.

Results

Groups A and B both showed higher alpha diversity than the healthy control group (P < 0.001) but alpha diversity did not differ significantly between groups A and B. Participants having type 1 diabetes with (P < 0.05) or without comorbid depression (P < 0.001) differed regarding beta diversity from healthy controls but not between each other. Group B (diabetes with depression) had significantly higher abundance of Megaspaera than groups A and C. Both diabetes groups had a higher abundance of Christensenellaceae, Succinivibrionaceae, and Rhodospirillaceae than the healthy group but similar between-group abundances.

Conclusions

While differences in alpha and beta diversity and in some bacterial taxa occurred only between participants with diabetes and healthy controls, specific characteristics regarding the abundance of Megasphaera were observed in people with diabetes and comorbid depression. In summary, the study findings indicate a possible involvement of bacterial groups in depression in people with diabetes. The results suggest replication studies in larger samples to verify these findings.

Disordered development of gut microbiome interferes with the establishment of the gut ecosystem during early childhood with atopic dermatitis

The gut microbiome influences the development of allergic diseases during early childhood. However, there is a lack of comprehensive understanding of microbiome-host crosstalk. Here, we analyzed the influence of gut microbiome dynamics in early childhood on atopic dermatitis (AD) and the potential interactions between host and microbiome that control this homeostasis. We analyzed the gut microbiome in 346 fecal samples (6-36 months; 112 non-AD, 110 mild AD, and 124 moderate to severe AD) from the Longitudinal Cohort for Childhood Origin of Asthma and Allergic Disease birth cohort. The microbiome-host interactions were analyzed in animal and in vitro cell assays. Although the gut microbiome maturated with age in both AD and non-AD groups, its development was disordered in the AD group. Disordered colonization of short-chain fatty acids (SCFA) producers along with age led to abnormal SCFA production and increased IgE levels. A butyrate deficiency and downregulation of GPR109A and PPAR-γ genes were detected in AD-induced mice. Insufficient butyrate decreases the oxygen consumption rate of host cells, which can release oxygen to the gut and perturb the gut microbiome. The disordered gut microbiome development could aggravate balanced microbiome-host interactions, including immune responses during early childhood with AD.

The Role of the Gut Microbiota in the Pathogenesis of Diabetes

Diabetes mellitus is a significant clinical and therapeutic problem because it can lead to serious long-term complications. Its pathogenesis is not fully understood, but there are indications that dysbiosis can play a role in the development of diabetes, or that it appears during the course of the disease. Changes in microbiota composition are observed in both type 1 diabetes (T1D) and type 2 diabetes (T2D) patients. These modifications are associated with pro-inflammation, increased intestinal permeability, endotoxemia, impaired β-cell function and development of insulin resistance. This review summarizes the role of the gut microbiota in healthy individuals and the changes in bacterial composition that can be associated with T1D or T2D. It also presents new developments in diabetes therapy based on influencing the gut microbiota as a promising method to alter the course of diabetes. Moreover, it highlights the lacking data and suggests future directions needed to prove the causal relationship between dysbiosis and diabetes, both T1D and T2D.

Immunopathology of Type 1 Diabetes and Immunomodulatory Effects of Stem Cells: A Narrative Review of the Literature

Type 1 Diabetes (T1D) is a complex autoimmune disorder which occurs as a result of an intricate series of pathologic interactions between pancreatic β-cells and a wide range of components of both the innate and the adaptive immune systems. Stem-cell therapy, a recently-emerged potentially therapeutic option for curative treatment of diabetes, is demonstrated to cause significant alternations to both different immune cells such as macrophages, natural killer (NK) cells, dendritic cells, T cells, and B cells and non-cellular elements including serum cytokines and different components of the complement system. Although there exists overwhelming evidence indicating that the documented therapeutic effects of stem cells on patients with T1D is primarily due to their potential for immune regulation rather than pancreatic tissue regeneration, to date, the precise underlying mechanisms remain obscure. On the other hand, immune-mediated rejection of stem cells remains one of the main obstacles to regenerative medicine. Moreover, the consequences of efferocytosis of stem-cells by the recipients' lung-resident macrophages have recently emerged as a responsible mechanism for some immune-mediated therapeutic effects of stem-cells. This review focuses on the nature of the interactions amongst different compartments of the immune systems which are involved in the pathogenesis of T1D and provides explanation as to how stem cell-based interventions can influence immune system and maintain the physiologic equilibrium.