Butyrate inhibits IL-1β-induced inflammatory gene expression by suppression of NF-κB activity in pancreatic beta cells

Immune-microbiota dysregulation in maintenance hemodialysis: a 16S rRNA sequencing-based analysis of gut flora and T cell profiles

BACKGROUND

Maintenance hemodialysis (MHD) patients frequently exhibit immune dysregulation and gut dysbiosis, both of which contribute to increased infection risk and adverse outcomes. However, the relationship between gut microbial composition and immune competence in this population remains underexplored.

METHODS

This study assessed 45 MHD patients and 30 healthy controls, stratifying MHD patients into immunocompetent (HD-NLI, CD4+/CD8+ ≥ 1) and immunodeficient (HD-LI, CD4+/CD8+ < 1) groups. Circulating cytokines (IL-6, IL-10, IL-12, TNF-α, IFN-γ) were quantified using ELISA. Gut microbiota profiles were derived via 16S rRNA gene sequencing (V3-V4 regions), followed by QIIME2 and LEfSe-based bioinformatics analyses.

RESULTS

HD-LI patients displayed severe T cell dysregulation and elevated pro-inflammatory cytokines. Compared to controls, HD patients had reduced abundance of beneficial taxa (e.g., Prevotella copri, Bacteroides vulgatus, Agathobacter), and enrichment of pro-inflammatory taxa (e.g., Escherichia-Shigella, Blautia, Citrobacter). LEfSe identified 39 discriminatory taxa with distinct immune group signatures. Redundancy analysis revealed that CD4+ levels, CD4+/CD8+ ratios, and TNF-α significantly shaped microbiota composition. Correlation analysis confirmed strong associations between immune parameters and microbial taxa involved in short-chain fatty acid (SCFA) metabolism.

CONCLUSION

This study provides novel evidence linking gut microbial dysbiosis to immune impairment in MHD patients. The findings suggest that SCFA-producing bacteria are depleted in immunodeficient states, offering a potential target for microbiota-directed immunomodulatory therapies in ESRD.

Dietary manipulation of intestinal microbes prolongs survival in a mouse model of Hirschsprung disease

Enterocolitis is a common and potentially deadly manifestation of Hirschsprung disease (HSCR) but disease mechanisms remain poorly defined. Unexpectedly, we discovered that diet can dramatically affect the lifespan of a HSCR mouse model ( Piebald lethal , sl/sl ) where affected animals die from HAEC complications. In the sl/sl model, diet alters gut microbes and metabolites, leading to changes in colon epithelial gene expression and epithelial oxygen levels known to influence colitis severity. Our findings demonstrate unrecognized similarity between HAEC and other types of colitis and suggest dietary manipulation could be a valuable therapeutic strategy for people with HSCR.

Abstract

Hirschsprung disease (HSCR) is a birth defect where enteric nervous system (ENS) is absent from distal bowel. Bowel lacking ENS fails to relax, causing partial obstruction. Affected children often have "Hirschsprung disease associated enterocolitis" (HAEC), which predisposes to sepsis. We discovered survival of Piebald lethal ( sl/sl ) mice, a well-established HSCR model with HAEC, is markedly altered by two distinct standard chow diets. A "Protective" diet increased fecal butyrate/isobutyrate and enhanced production of gut epithelial antimicrobial peptides in proximal colon. In contrast, "Detrimental" diet-fed sl/sl had abnormal appearing distal colon epithelium mitochondria, reduced epithelial mRNA involved in oxidative phosphorylation, and elevated epithelial oxygen that fostered growth of inflammation-associated Enterobacteriaceae . Accordingly, selective depletion of Enterobacteriaceae with sodium tungstate prolonged sl/sl survival. Our results provide the first strong evidence that diet modifies survival in a HSCR mouse model, without altering length of distal colon lacking ENS.

Highlights

Two different standard mouse diets alter survival in the Piebald lethal ( sl/sl ) mouse model of Hirschsprung disease, without impacting extent of distal colon aganglionosis (the region lacking ENS). Piebald lethal mice fed the "Detrimental" diet had many changes in colon epithelial transcriptome including decreased mRNA for antimicrobial peptides and genes involved in oxidative phosphorylation. Detrimental diet fed sl/sl also had aberrant-appearing mitochondria in distal colon epithelium, with elevated epithelial oxygen that drives lethal Enterobacteriaceae overgrowth via aerobic respiration. Elimination of Enterobacteriaceae with antibiotics or sodium tungstate improves survival of Piebald lethal fed the "Detrimental diet".

Graphical abstract

Artificial sweeteners and Type 2 Diabetes Mellitus: A review of current developments and future research directions

While artificial sweeteners are Generally Regarded as Safe (GRAS), the scientific community remains divided on their safety status. The previous assumption that artificial sweeteners are inert within the body is no longer valid. Artificial sweeteners, known for their high intense sweetness and low or zero calories, are extensively used today in food and beverage products as sugar substitutes and are sometimes recommended for weight management and Type 2 Diabetes Mellitus (T2DM) patients. The general omission of information about the concentration of artificial sweeteners on market product labels makes it challenging to determine the amounts of artificial sweeteners consumed by people. Despite regulatory authorization for their usage, such as from the United States Food and Drug Administration (FDA), concerns remain about their potential association with metabolic diseases, such as T2DM, which the artificial sweeteners were supposed to reduce. This review discusses the relationship between artificial sweetener consumption and the risk of developing T2DM. With the increasing number of recent scientific studies adding to the debate on this subject matter, we assessed recent literature and up-to-date evidence. Importantly, we highlight future research directions toward furthering knowledge in this field of study.

Gut bacterium Intestinimonas butyriciproducens improves host metabolic health: evidence from cohort and animal intervention studies

BACKGROUND

The human gut microbiome strongly influences host metabolism by fermenting dietary components into metabolites that signal to the host. Our previous work has shown that Intestinimonas butyriciproducens is a prevalent commensal bacterium with the unique ability to convert dietary fructoselysine to butyrate, a well-known signaling molecule with proven health benefits. Dietary fructoselysine is an abundant Amadori product formed in foods during thermal treatment and is part of foods rich in dietary advanced glycation end products which have been associated with cardiometabolic disease. It is therefore of interest to investigate the causal role of this bacterium and fructoselysine metabolism in metabolic disorders.

RESULTS

We assessed associations of I. butyriciproducens with metabolic risk biomarkers at both strain and functional levels using a human cohort characterized by fecal metagenomic analysis. We observed that the level of the bacterial strain as well as fructoselysine fermentation genes were negatively associated with BMI, triglycerides, HbA1c, and fasting insulin levels. We also investigated the fructoselysine degradation capacity within the Intestinimonas genus using a culture-dependent approach and found that I. butyriciproducens is a key player in the butyrogenic fructoselysine metabolism in the gut. To investigate the function of I. butyriciproducens in host metabolism, we used the diet-induced obesity mouse model to mimic the human metabolic syndrome. Oral supplementation with I. butyriciproducens counteracted body weight gain, hyperglycemia, and adiposity. In addition, within the inguinal white adipose tissue, bacterial administration reduced inflammation and promoted pathways involved in browning and insulin signaling. The observed effects may be partly attributable to the formation of the short-chain fatty acids butyrate from dietary fructoselysine, as butyrate plasma and cecal levels were significantly increased by the bacterial strain, thereby contributing to the systemic effects of the bacterial treatment.

CONCLUSIONS

I. butyriciproducens ameliorates host metabolism in the context of obesity and may therefore be a good candidate for new microbiota-therapeutic approaches to prevent or treat metabolic diseases. Video Abstract.

The role of the gut microbiome in modulating immunotherapy efficacy in colorectal cancer

This systematic literature review and meta-analysis provide an overview of the critical role of gut microbiota in modulating the efficacy of immunotherapy for colorectal cancer. Gut microbes influence host immune responses through multiple mechanisms including modulation of immune cell activity, metabolite action, and immune tolerance. The ability of specific gut microbes to improve the efficacy of immune checkpoint inhibitors has been linked to their ability to improve gut barrier function, modulate immune cell activity, and produce key immunomodulatory metabolites such as short-chain fatty acids. In addition, the composition and diversity of the gut microbiota are strongly associated with the efficacy of immunotherapies, demonstrating the potential to improve therapeutic response by modifying the gut microbiota. This paper also discusses the prospect of manipulating the gut microbiota through strategies such as fecal microbial transplantation, probiotic supplementation, and dietary modifications to optimize the efficacy of immunotherapy.

Diabetes and the associated complications: The role of antioxidants in diabetes therapy and care

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high blood sugar levels (hyperglycemia). Poorly managed diabetes can lead to complications affecting multiple organ systems. Antioxidants play a crucial role in reducing oxidative stress caused by reactive oxygen species (ROS), primarily triggered by uncontrolled high blood sugar levels in diabetes. Antioxidants like vitamin C, E, selenium, and alpha-lipoic acid, when used as supplements, have shown promise in reducing oxidative stress markers and improving antioxidant status in laboratory and animal studies and diabetic patients. Antioxidant supplementation may help reduce the risk of diabetic complications such as neuropathy, nephropathy, retinopathy, and cardiovascular disease. Additionally, antioxidants also have anti-inflammatory properties, which could be beneficial in reducing inflammation associated with diabetes. Antioxidant supplementation has been shown to enhance endothelial function, insulin sensitivity, and glucose metabolism, thereby aiding in glycemic control and overall diabetic management. Combining antioxidants with certain medications may have therapeutic benefits, such as effectively neutralizing free radicals and enhancing the regulation of antioxidant defense systems. This review presents an update on diabetes, the sources of free radical generation, the body's natural defense mechanisms, the clinical evidence regarding using antioxidants in managing diabetic complications, and the potential new therapeutic approaches. Overall, antioxidant supplementation may offer some benefits in managing diabetic complications. However, further studies are needed to understand the mechanisms of action, determine the optimal supplementation, explore potential interactions with other medications, and conduct long-term studies to establish the possible use of antioxidants for optimal benefits in diabetes care.

Causal effect of gut microbiota on venous thromboembolism: a two-sample mendelian randomization study

BACKGROUND

The gut microbiota of venous thromboembolism (VTE) patients exhibited significant alterations. However, the causal relationship between gut microbiota and VTE has not been fully understood. This study aimed to assess the causal relationship between gut microbiota and the risk of VTE using a two-sample Mendelian Randomization (MR) study.

METHODS

The gut microbiota and VTE genetic data were collected from the MiBioGen consortium and the UK biobank, respectively. The potential causal relationship between gut microbiota and VTE was investigated using a two-sample MR analysis, including inverse variance weighted (IVW), weighted median, MR-Egger, simple mode, and weighted mode methods. Cochran's Q-test, MR-PRESSO, and MR-Egger regression intercept analysis were utilized to perform sensitivity analysis.

RESULTS

At the genus level, the results of MR analysis found that Coprococcus1 (OR: 1.0029, 95% CI: 1.0005-1.0054, p = 0.0202) was suggestively linked with an increased risk of VTE, while Slackia (odds ratio (OR): 0.9977, 95% confidence interval (CI): 0.9957-0.9998, p = 0.0298), Butyricicoccus (OR: 0.9971, 95% CI: 0.9945-0.9997, p = 0.0309), Eubacterium coprostanoligenes group (OR: 0.9972, 95% CI: 0.9946-0.9999, p = 0.0445), and Bacteroides (OR: 0.9964, 95% CI: 0.9932-0.9995, p = 0.0234) were suggestively associated with a reduced risk of VTE. No heterogeneity and horizontal pleiotropy was detected.

CONCLUSION

This study found that there were potential causal relationships between five gut microbiota and VTE. Our findings may provide new insights into the mechanisms of VTE.

Artificial sweetener-induced dysbiosis and associated molecular signatures

Despite their approval for inclusion in beverages, and food products, the safety of artificial sweeteners is still a topic of debate within the scientific community. A significant aspect of this debate focuses on the potential of artificial sweeteners to induce dysbiosis, an imbalance in the intestinal microbiota, which has been associated with many diseases including obesity, Type 2 diabetes, and cardiovascular diseases. The interactions and mechanisms of action of artificial sweeteners within the gut microbiota, as well as the extent of associated molecular alterations, are still under active investigation. This review aims to evaluate recent developments in artificial sweetener-induced dysbiosis with its associated molecular signatures. Importantly, potential future directions for research are proposed, offering insights that could guide further targeted studies and inform dietary recommendations and policy revisions.

Protection of beta cells against cytokine-induced apoptosis by the gut microbial metabolite butyrate

Type 1 diabetes (T1D) is characterized by immune cell infiltration in the islets of Langerhans, leading to the destruction of insulin-producing beta cells. This destruction is driven by secreted cytokines and cytotoxic T cells inducing apoptosis in beta cells. Butyrate, a metabolite produced by the gut microbiota, has been shown to have various health benefits, including anti-inflammatory and anti-diabetic effects. In this study, we investigated the potential protective effects of butyrate on cytokine-induced apoptosis in beta cells and explored the underlying mechanisms. Insulin-secreting INS-1E cells and isolated mouse islets were treated with interleukin-1beta (IL-1β) or a combination of IL-1β and interferon-gamma (IFN-γ) in the presence or absence of butyrate. We analyzed apoptosis, nitric oxide (NO) levels, expression of stress-related genes, and immune cell migration. Our results demonstrated that butyrate significantly attenuated cytokine-induced apoptosis in both INS-1E cells and mouse islets, accompanied by a reduction in NO levels. Butyrate also decreased the expression of endoplasmic reticulum (ER) stress markers such as Chop, phosphorylated eIF2α and Atf4, as well as some pro-apoptotic genes including Dp5 and Puma. Butyrate reduced the cytokine-induced expression of the chemokine genes Cxcl1 and Cxcl10 in mouse islets, as well as the chemotactic activity of THP-1 monocytes toward conditioned media from IL-1β-exposed islets. In conclusion, these findings indicate that butyrate protects beta cells from cytokine-induced apoptosis and ER stress, suggesting its potential as a therapeutic agent to prevent beta cell destruction in T1D.

Roseburia intestinalis: A possible target for vascular calcification

With the advancement of metagenomics and metabolomics techniques, the crucial role of the gut microbiome in intestinal, cardiovascular, and metabolic disorders has been extensively explored. Vascular calcification (VC) is common in atherosclerosis, hypertension, diabetes mellitus, and chronic kidney disease. Moreover, it is a significant cause of cardiovascular diseases and mortality. Roseburia intestinalis, as a promising candidate for the next generation of probiotics, plays a substantial role in inhibiting the systemic inflammatory response and holds great potential in the treatment of intestinal diseases, cardiovascular diseases, and metabolic disorders. Its primary metabolite, butyrate, acts on specific receptors (GPR43, GPR41, GPR109a). It enters cells via transporters (MCT1, SMCT1), affecting gene expression through HDACs, PPARγ and Nrf2, promoting energy metabolism and changing the concentration of other metabolites (including AGEs, LPS, BHB) in the circulation to affect the body's life activities. In this paper, we focus on the possible mechanism of the primary metabolite butyrate of Roseburia intestinalis in inhibiting VC, which may become a potential therapeutic target for the treatment of VC and the ways to enhance its effect.

Effect of Culture Supernatant of Clostridium butyricum TO-A on Human DNA-Repair-Factor-Encoding Gene Promoters

In this study, Clostridium butyricum TO-A culture supernatant (CBCS) or butyric acid was added to a culture medium of human cervical carcinoma HeLa S3 cells, and changes in DNA-repair-related gene promoter activities were investigated. The HeLa S3 cells were transfected with a luciferase (Luc) expression vector containing approximately 500 bp of the 5'-upstream region of several human DNA-repair-related genes and cultured with a medium containing the CBCS (10%) or butyric acid (2.5 mM). The cells were harvested after 19 to 42 h of incubation. A Luc assay revealed that the human ATM, PARG, PARP1, and RB1 gene promoter activities were significantly increased. A Western blot analysis showed that the amounts of the proteins encoded by these genes markedly increased. Furthermore, 8, 24, and 48 h after the addition of the CBCS (10%), total RNA was extracted and subjected to RNAseq analysis. The results showed that the expression of several inflammation- and DNA-replication/repair-related genes, including NFKB and the MCM gene groups, decreased markedly after 8 h. However, the expression of the histone genes increased after 24 h. Elucidation of the mechanism by which the CBCS and butyrate affect the expression of genes that encode DNA-repair-associated proteins may contribute to the prevention of carcinogenesis, the risk of which rises in accordance with aging.

Antioxidant synergistic anti-inflammatory effect in the MAPK/NF-κB pathway of peptide KGEYNK (KK-6) from giant salamander (Andrias davidianus)

BACKGROUND

Giant salamander protein peptide is a peptide with rich functional properties. Giant salamander protein peptide KGEYNK (KK-6) is a peptide with both antioxidant and anti-inflammatory properties. The antioxidant and anti-inflammatory mechanisms of KK-6 are still unclear. When we studied the functional mechanism of KK-6, we found that the antioxidant property of KK-6 has a synergistic and promoting effect on anti-inflammatory properties.

RESULTS

KK-6 enhances cellular resistance to LPS via the MAPK/NF-κB signaling pathway, leading to increased levels of inflammatory factors: interleukin-1β (764.81 ng mL-1), interleukin-6 (1.06 ng mL-1) and tumor necrosis factor-α (4440.45 ng mL-1). KK-6 demonstrates potent antioxidant properties by activating the Nrf2 signaling pathway, resulting in elevated levels of antioxidant enzymes (glutathione peroxidase: 0.03 μg mL-1; superoxide dismutase: 0.589 μg mL-1) and a reduction in the concentration of the oxidative product malondialdehyde (967.05 μg mL-1).

CONCLUSION

Our findings highlight the great potential of KK-6, a peptide extracted from giant salamander protein, as a remedy for intestinal inflammation. Through its dual role as an antioxidant and anti-inflammatory agent, KK-6 offers a promising avenue for alleviating inflammation-related damage and oxidative stress. This study lays the foundation for further exploration of giant salamander products and highlights their importance in health and novel food development. © 2024 Society of Chemical Industry.

Impact of Gut Microbiota and SCFAs in the Pathogenesis of PCOS and the Effect of Metformin Therapy

Polycystic ovary syndrome (PCOS) is a complex disorder that impacts both the endocrine and metabolic systems, often resulting in infertility, obesity, insulin resistance, and cardiovascular complications. The aim of this study is to investigate the role of intestinal flora and its metabolites, particularly short-chain fatty acids (SCFAs), in the development of PCOS, and to assess the effects of metformin therapy on these components. SCFA levels in fecal and blood samples from women with PCOS (n=69) and healthy controls (n=18) were analyzed using Gas Chromatography-Mass Spectrometry (GC/MS) for precise measurement. Fecal microbiota were quantitatively detected by real-time polymerase chain reaction (PCR). To assess the efficacy of six months of metformin treatment, changes in the microbiota and SCFAs in the PCOS group (n=69) were also evaluated. The results revealed that women with PCOS exhibited a significant reduction in beneficial bacteria (namely, the C. leptum group and Prevotella spp.) alongside a notable overgrowth of opportunistic microorganisms (C. perfringens, C. difficile, Staphylococcus spp., and Streptococcus spp.). An overproduction of acetic acid (AA, FC=0.47, p<0.05) and valeric acid (VA, FC=0.54, p<0.05) suggests a link between elevated SCFAs and the development of obesity and PCOS. Interestingly, AA in the bloodstream might offer a protective effect against PCOS by ameliorating key symptoms such as high body mass index (r=-0.33, p=0.02), insulin resistance (r=-0.39, p=0.02), and chronic inflammation. Although serum SCFA levels showed non-significant changes following metformin treatment (p>0.05), the normalization of AA in the gut underscores that metformin exerts a more pronounced effect locally within the gastrointestinal tract. Furthermore, the study identified the most effective model for predicting the success of metformin therapy, based on serum concentrations of butyric acid (BA) and VA, achieving a 91% accuracy rate, 100% sensitivity, and 80% specificity. These promising findings highlight the potential for developing targeted interventions and personalized treatments, ultimately improving clinical outcomes for women with PCOS.

Immune mRNA Expression and Fecal Microbiome Composition Change Induced by Djulis (Chenopodium formosanum Koidz.) Supplementation in Aged Mice: A Pilot Study

Background and Objectives: The aging process has always been associated with a higher susceptibility to chronic inflammatory lung diseases. Several studies have demonstrated the gut microbiome's influence on the lungs through cross-talk or the gut-lungs axis maintaining nutrient-rich microenvironments. Taiwan djulis (Chenopodium formosanum Koidz.) provides antioxidant and anti-inflammatory characteristics that could modulate the gut microbiome. This could induce the gut-lung axis through microbial cross-talk, thus favoring the modulation of lung inflammation. Materials and Methods: Here, we investigate the immune mRNA expression in the spleen, fecal microbiome composition, and hyperplasia of the bronchial epithelium in aged 2-year-old BALB/c mice after 60 days of supplementation of djulis. Results: The pro-inflammatory cytokines IFN-γ, TNF-α, and IL-1β, T; cells CD4 and CD8; and TLRs TLR3, TLR4, TLR5, TLR7, TLR8, and TLR9 were reduced in their mRNA expression levels, while the anti-inflammatory cytokines IL-2, IL-4, and IL-10 were highly expressed in the C. formosanum-treated group. Interestingly, the fecal microbiome composition analysis indicated higher diversity in the C. formosanum-treated group and the presence of butyrate-producing bacteria that are beneficial in the gut microbiome. The histopathology showed reduced hyperplasia of the bronchial epithelium based on the degree of lesions. Conclusions: Our findings suggest that Taiwan djulis can modulate the gut microbiome, leading to microbial cross-talk; reducing the mRNA expression of pro-inflammatory cytokines, T cells, and TLRs; and increasing anti-inflammatory cytokines in the spleen, as cytokines migrate in the lungs, preventing lung inflammation damage in aged mice or the gut-lung axis. Thus, Taiwan djulis could be considered a beneficial dietary component for the older adult population. The major limitation includes a lack of protein validation of cytokines and TLRs and quantification of the T cell population in the spleen as a marker of the gut-lung axis.

Oxidative stress and food as medicine

There has been a sea of change in our understanding of the contribution of food to both our well-being and disease states. When one addresses "food as medicine," the concept of oxidative stress needs to be included. This review interconnects the basic science findings of oxidative stress and redox balance with the medicinal use of food, emphasizing optimization of the redox balance. To better illustrate the impacts of oxidative stress, the concept of the "triple oxidant sink" is introduced as a theoretical gauge of redox balance. Utilizing the concept, the true importance of dietary and lifestyle factors can be emphasized, including the limitations of supplements or a handful of "superfoods," if the remainder of the factors are pro-oxidant. The effects of a whole plant food diet compared with those of dietary supplements, processed foods, animal based nutrients, or additional lifestyle factors can be visually demonstrated with this concept. This paper provides an overview of the process, acknowledging that food is not the only mechanism for balancing the redox status, but one that can be strategically used to dramatically improve the oxidative state, and thus should be used as medicine.

Sodium butyrate prevents cytokine-induced β-cell dysfunction through restoration of stromal interaction molecule 1 expression and activation of store-operated calcium entry

Sodium butyrate (NaB) improves β-cell function in preclinical models of diabetes; however, the mechanisms underlying these beneficial effects have not been fully elucidated. In this study, we investigated the impact of NaB on β-cell function and calcium (Ca2+) signaling using ex vivo and in vitro models of diabetes. Our results show that NaB significantly improved glucose-stimulated insulin secretion in islets from human organ donors with type 2 diabetes and in cytokine-treated INS-1 β cells. Consistently, NaB improved glucose-stimulated Ca2+ oscillations in mouse islets treated with proinflammatory cytokines. Because the oscillatory phenotype of Ca2+ in the β cell is governed by changes in endoplasmic reticulum (ER) Ca2+ levels, we explored the relationship between NaB and store-operated calcium entry (SOCE), a rescue mechanism that acts to refill ER Ca2+ levels through STIM1-mediated gating of plasmalemmal Orai channels. We found that NaB treatment preserved basal ER Ca2+ levels and restored SOCE in IL-1β-treated INS-1 cells. Furthermore, we linked these changes with the restoration of STIM1 levels in cytokine-treated INS-1 cells and mouse islets, and we found that NaB treatment was sufficient to prevent β-cell death in response to IL-1β treatment. Mechanistic experiments revealed that NaB mediated these beneficial effects in the β-cell through histone deacetylase (HDAC) inhibition, iNOS suppression, and modulation of AKT-GSK-3 signaling. Taken together, these data support a model whereby NaB treatment promotes β-cell function and Ca2+ homeostasis under proinflammatory conditions through pleiotropic effects that are linked with maintenance of SOCE. These results also suggest a relationship between β-cell SOCE and gut microbiome-derived butyrate that may be relevant in the treatment and prevention of diabetes.

The mechanisms in the gut microbiota regulation and type 2 diabetes therapeutic activity of resistant starches

Resistant starch (RS) can potentially prevent type 2 diabetes through the modulation of intestinal microbiota and microbial metabolites. Currently, it has been wildly noted that altering the intestinal microbial composition and short-chain fatty acids levels can achieve therapeutic effects, although the specific mechanisms were rarely elucidated. This review systematically explores the structural characteristics of different RS, analyzes the cross-feeding mechanism utilized by intestinal microbiota, and outlines the pathways and targets of butyrate, a primary microbial metabolite, for treating diabetes. Different RS types may have a unique impact on microbiota composition and their cross-feeding, thus exploring regulatory mechanisms of RS on diabetes through intestinal flora interaction and their metabolites could pave the way for more effective treatment outcomes for host health. Furthermore, by understanding the mechanisms of strain-level cross-feeding and metabolites of RS, precise dietary supplementation methods targeted at intestinal composition and metabolites can be achieved to improve T2DM.

Targeting β-Cell Plasticity: A Promising Approach for Diabetes Treatment

The β-cells within the pancreas play a pivotal role in insulin production and secretion, responding to fluctuations in blood glucose levels. However, factors like obesity, dietary habits, and prolonged insulin resistance can compromise β-cell function, contributing to the development of Type 2 Diabetes (T2D). A critical aspect of this dysfunction involves β-cell dedifferentiation and transdifferentiation, wherein these cells lose their specialized characteristics and adopt different identities, notably transitioning towards progenitor or other pancreatic cell types like α-cells. This process significantly contributes to β-cell malfunction and the progression of T2D, often surpassing the impact of outright β-cell loss. Alterations in the expressions of specific genes and transcription factors unique to β-cells, along with epigenetic modifications and environmental factors such as inflammation, oxidative stress, and mitochondrial dysfunction, underpin the occurrence of β-cell dedifferentiation and the onset of T2D. Recent research underscores the potential therapeutic value for targeting β-cell dedifferentiation to manage T2D effectively. In this review, we aim to dissect the intricate mechanisms governing β-cell dedifferentiation and explore the therapeutic avenues stemming from these insights.

The Role of Short Chain Fatty Acids in Inflammation and Body Health

Short chain fatty acids (SCFAs), mainly including acetate, propionate and butyrate, are produced by intestinal bacteria during the fermentation of partially digested and indigestible polysaccharides. SCFAs play an important role in regulating intestinal energy metabolism and maintaining the homeostasis of the intestinal environment and also play an important regulatory role in organs and tissues outside the gut. In recent years, many studies have shown that SCFAs can regulate inflammation and affect host health, and two main signaling mechanisms have also been identified: the activation of G-protein coupled receptors (GPCRs) and inhibition of histone deacetylase (HDAC). In addition, a growing body of evidence highlights the importance of every SCFA in influencing health maintenance and disease development. In this review, we summarized the recent advances concerning the biological properties of SCFAs and their signaling pathways in inflammation and body health. Hopefully, it can provide a systematic theoretical basis for the nutritional prevention and treatment of human diseases.

Ehmt2 inactivation in pancreatic epithelial cells shapes the transcriptional landscape and inflammation response of the whole pancreas

Introduction: The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs. Recently, we have shown that Ehmt2 inactivation in the mouse pancreas alters growth and immune gene expression networks, antagonizing Kras-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of Ehmt2 in maintaining a transcriptional landscape that protects organs from inflammation. Methods: Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from Ehmt2 conditional knockout animals (Ehmt2 fl/fl ) targeted to the exocrine pancreatic epithelial cells (Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammation-repair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the Ehmt2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. Results and discussion: The Ehmt2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional Ehmt2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammation-repair reaction with a small contribution of specific Ehmt2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the Ehmt2-mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.

Dietary Fiber-Derived Butyrate Alleviates Piglet Weaning Stress by Modulating the TLR4/MyD88/NF-κB Pathway

During weaning, piglets are susceptible to intestinal inflammation and impairment in barrier function. Dietary fiber (DF) plays an active role in alleviating weaning stress in piglets. However, the effects of different sources of dietary fiber on the performance of weaned piglets are inconsistent, and the mechanisms through which they affect intestinal health need to be explored. Therefore, in this study, sixty weaned piglets were randomly divided into three treatment groups: basal diet (control, CON), beet pulp (BP), and alfalfa meal (AM) according to the feed formulation for a 28-day trial. The results showed that both AM and BP groups significantly reduced diarrhea rate and serum inflammatory factors (IL-1β and TNF-α) and increased antioxidant markers (T-AOC and SOD), in addition to decreasing serum MDA and ROS concentrations in the AM group. At the same time, piglets in the AM group showed a significant reduction in serum intestinal permeability indices (LPS and DAO) and a substantial increase in serum immunoglobulin levels (IgA, IgG, and IgM) and expression of intestinal barrier-associated genes (Claudin1, Occludin, ZO-1, and MUC1), which resulted in an improved growth performance. Interestingly, the effect of DF on intestinal inflammation and barrier function can be attributed to its modulation of gut microbes. Fiber-degrading bacteria enriched in the AM group (Christensenellaceae_R-7_group, Pediococcus and Weissella) inhibited the production of TLR4- through the promotion of SCFAs (especially butyrate). MyD88-NF-κB signaling pathway activation reduces intestinal inflammation and repairs intestinal barrier function. In conclusion, it may provide some theoretical support and rationale for AM to alleviate weaning stress and improve early intestinal dysfunction, which may have implications for human infants.

EHMT2 Inactivation in Pancreatic Epithelial Cells Shapes the Transcriptional Landscape and Inflammation Response of the Whole Pancreas

The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs. Recently, we have shown that EHMT2 inactivation alters growth and immune gene expression networks, antagonizing KRAS-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of EHMT2 in maintaining a transcriptional landscape that protects organs from inflammation. Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from EHMT2 conditional knockout animals ( EHMT2 fl/fl ) targeted to the exocrine pancreatic epithelial cells ( Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammation-repair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the EHMT2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. The EHMT2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional EHMT2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammation-repair reaction with a small contribution of specific EHMT2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the EHMT2-mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.

Butyrate functions as a histone deacetylase inhibitor to protect pancreatic beta cells from IL-1β-induced dysfunction

Butyrate, a gut microbial metabolite, has beneficial effects on glucose homeostasis and has become an attractive drug candidate for type 2 diabetes (T2D). Recently, we showed that butyrate protects pancreatic beta cells against cytokine-induced dysfunction. In this study, we explored the underlying mechanisms of butyrate action. Pancreatic mouse islets were exposed to a non-cytotoxic concentration of interleukin-1β (IL-1β) for 10 days to mimic low-grade inflammation in T2D. Similar to the effect of butyrate, an isoform-selective histone deacetylase 3 (HDAC3) inhibitor normalized IL-1β-reduced glucose-stimulated insulin secretion and insulin content. In contrast, free fatty acid receptor 2 and 3 (FFAR2/3) agonists failed to normalize IL-1β-induced beta cell dysfunction. Furthermore, butyrate inhibited HDAC activity and increased the acetylation of histone H3 and H4 by 3- and 10-fold, respectively. Genome-wide analysis of histone H3 lysine 27 acetylation (H3K27ac) revealed that butyrate mainly increased H3K27ac at promoter regions (74%), while H3K27ac peaks regulated by IL-1β were more equally distributed at promoters (38%), introns (23%) and intergenic regions (23%). Gene ontology analysis showed that butyrate increased IL-1β-reduced H3K27ac levels near several genes related to hormone secretion and reduced IL-1β-increased H3K27ac levels near genes associated with inflammatory responses. Butyrate alone increased H3K27ac near many genes related to MAPK signaling, hormone secretion, and differentiation, and decreased H3K27ac at genes involved in cell replication. Together, these results suggest that butyrate prevents IL-1β-induced pancreatic islet dysfunction by inhibition of HDACs resulting in changes in H3K27ac levels at genes relevant for beta cell function and inflammatory responses.

HAMSAB diet ameliorates dysfunctional signaling in pancreatic islets in autoimmune diabetes

An altered gut microbiota is associated with type 1 diabetes (T1D), affecting the production of short-chain fatty acids (SCFA) and glucose homeostasis. We previously demonstrated that enhancing serum acetate and butyrate using a dietary supplement (HAMSAB) improved glycemia in non-obese diabetic (NOD) mice and patients with established T1D. The effects of SCFA on immune-infiltrated islet cells remain to be clarified. Here, we performed single-cell RNA sequencing on islet cells from NOD mice fed an HAMSAB or control diet. HAMSAB induced a regulatory gene expression profile in pancreas-infiltrated immune cells. Moreover, HAMSAB maintained the expression of β-cell functional genes and decreased cellular stress. HAMSAB-fed mice showed preserved pancreatic endocrine cell identity, evaluated by decreased numbers of poly-hormonal cells. Finally, SCFA increased insulin levels in human β-like cells and improved transplantation outcome in NOD/SCID mice. Our findings support the use of metabolite-based diet as attractive approach to improve glucose control in T1D.

Apolipoprotein L genes are novel mediators of inflammation in beta cells

AIMS/HYPOTHESIS

Inflammation induces beta cell dysfunction and demise but underlying molecular mechanisms remain unclear. The apolipoprotein L (APOL) family of genes has been associated with innate immunity and apoptosis in non-pancreatic cell types, but also with metabolic syndrome and type 2 diabetes mellitus. Here, we hypothesised that APOL genes play a role in inflammation-induced beta cell damage.

METHODS

We used single-cell transcriptomics datasets of primary human pancreatic islet cells to study the expression of APOL genes upon specific stress conditions. Validation of the findings was carried out in EndoC-βH1 cells and primary human islets. Finally, we performed loss- and gain-of-function experiments to investigate the role of APOL genes in beta cells.

RESULTS

APOL genes are expressed in primary human beta cells and APOL1, 2 and 6 are strongly upregulated upon inflammation via the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway. APOL1 overexpression increases endoplasmic reticulum stress while APOL1 knockdown prevents cytokine-induced beta cell death and interferon-associated response. Furthermore, we found that APOL genes are upregulated in beta cells from donors with type 2 diabetes compared with donors without diabetes mellitus.

CONCLUSIONS/INTERPRETATION

APOLs are novel regulators of islet inflammation and may contribute to beta cell damage during the development of diabetes.

DATA AVAILABILITY

scRNAseq data generated by our laboratory and used in this study are available in the Gene Expression Omnibus (GEO; www.ncbi.nlm.nih.gov/geo/ ), accession number GSE218316.

A narrative review: CXC chemokines influence immune surveillance in obesity and obesity-related diseases: Type 2 diabetes and nonalcoholic fatty liver disease

Adipose tissue develops lipids, aberrant adipokines, chemokines, and pro-inflammatory cytokines as a consequence of the low-grade systemic inflammation that characterizes obesity. This low-grade systemic inflammation can lead to insulin resistance (IR) and metabolic complications, such as type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD). Although the CXC chemokines consists of numerous regulators of inflammation, cellular function, and cellular migration, it is still unknown that how CXC chemokines and chemokine receptors contribute to the development of metabolic diseases (such as T2D and NAFLD) during obesity. In light of recent research, the objective of this review is to provide an update on the linkage between the CXC chemokine, obesity, and obesity-related metabolic diseases (T2D and NAFLD). We explore the differential migratory and immunomodulatory potential of CXC chemokines and their mechanisms of action to better understand their role in clinical and laboratory contexts. Besides that, because CXC chemokine profiling is strongly linked to leukocyte recruitment, macrophage recruitment, and immunomodulatory potential, we hypothesize that it could be used to predict the therapeutic potential for obesity and obesity-related diseases (T2D and NAFLD).

Complex regulatory effects of gut microbial short-chain fatty acids on immune tolerance and autoimmunity

Immune tolerance deletes or suppresses autoreactive lymphocytes and is established at multiple levels during the development, activation and effector phases of T and B cells. These mechanisms are cell-intrinsically programmed and critical in preventing autoimmune diseases. We have witnessed the existence of another type of immune tolerance mechanism that is shaped by lifestyle choices, such as diet, microbiome and microbial metabolites. Short-chain fatty acids (SCFAs) are the most abundant microbial metabolites in the colonic lumen and are mainly produced by the microbial fermentation of prebiotics, such as dietary fiber. This review focuses on the preventive and immunomodulatory effects of SCFAs on autoimmunity. The tissue- and disease-specific effects of dietary fiber, SCFAs and SCFA-producing microbes on major types of autoimmune diseases, including type I diabetes, multiple sclerosis, rheumatoid arthritis and lupus, are discussed. Additionally, their key regulatory mechanisms for lymphocyte development, tissue barrier function, host metabolism, immunity, autoantibody production, and inflammatory effector and regulatory lymphocytes are discussed. The shared and differential effects of SCFAs on different types and stages of autoimmune diseases are discussed.

Targeted Delivery of Butyrate Improves Glucose Homeostasis, Reduces Hepatic Lipid Accumulation and Inflammation in db/db Mice

Butyrate produced by the gut microbiota has beneficial effects on metabolism and inflammation. Butyrate-producing bacteria are supported by diets with a high fiber content, such as high-amylose maize starch (HAMS). We investigated the effects of HAMS- and butyrylated HAMS (HAMSB)-supplemented diets on glucose metabolism and inflammation in diabetic db/db mice. Mice fed HAMSB had 8-fold higher fecal butyrate concentration compared to control diet-fed mice. Weekly analysis of fasting blood glucose showed a significant reduction in HAMSB-fed mice when the area under the curve for all five weeks was analyzed. Following treatment, fasting glucose and insulin analysis showed increased homeostatic model assessment (HOMA) insulin sensitivity in the HAMSB-fed mice. Glucose-stimulated insulin release from isolated islets did not differ between the groups, while insulin content was increased by 36% in islets of the HAMSB-fed mice. Expression of insulin 2 was also significantly increased in islets of the HAMSB-fed mice, while no difference in expression of insulin 1, pancreatic and duodenal homeobox 1, MAF bZIP transcription factor A and urocortin 3 between the groups was observed. Hepatic triglycerides in the livers of the HAMSB-fed mice were significantly reduced. Finally, mRNA markers of inflammation in liver and adipose tissue were reduced in mice fed HAMSB. These findings suggest that HAMSB-supplemented diet improves glucose metabolism in the db/db mice, and reduces inflammation in insulin-sensitive tissues.

Relationships between Diabetes and the Intestinal Microbial Population

Diabetes is a metabolic disorder characterized by lower responsiveness of tissues to insulin and consequent large variations in circulating levels of glucose. This fluctuation has harmful effects as both hyperglycemia and hypoglycemia can be very injurious. The causes of diabetes are varied but the consequences are rather uniform. Dietary factors are important especially in adult onset type 2 diabetes (T2D) while type 1 diabetes (T1D) is characterized by having a stronger heritable component and involving autoimmune attach on pancreatic beta cells. This review is focused on the relation of the bacterial components found within the intestine, to the establishment and maintenance of diabetes. The precise composition of the gut microbiome is increasingly recognized as a factor in organismic health and its interaction with a variety of disease states has been described. This is especially marked in the case of diabetes since the nature of the diet is an important factor in establishing both the microbiome and the incidence of diabetes. The bidirectional nature of this relationship is discussed. The effects of disease that lead to altered microbiomal composition together with aberrant metabolic changes are also included. Emphasis is given to the important role of short chain fatty acids (SCFAs) as mediators of the microbiome-diabetes relation.