Colonic Pro-inflammatory Macrophages Cause Insulin Resistance in an Intestinal Ccl2/Ccr2-Dependent Manner

Gut commensal Phascolarctobacterium faecium retunes innate immunity to mitigate obesity and metabolic disease in mice

The gut microbiota may protect against obesity and chronic metabolic conditions by regulating the immune response to dietary triggers. Yet the specific bacteria that control the overactivation of the immune system in obesity and their mode of action remain largely unknown. Here we surveyed 7,569 human metagenomes and observed an association between the gut symbiont Phascolarctobacterium faecium and non-obese adults regardless of nationality, sex or age. In a mouse model of diet-induced obesity, we confirmed the specificity of P. faecium DSM 32890 anti-obesogenic properties compared with other species of the same genus. P. faecium reversed the inflammatory phenotype associated with obesity. Specifically, P. faecium promoted polarization of alternatively activated macrophages (M2), which reversed the obesity-induced increase in gut-resident type 1 innate lymphoid cells. This resulted in mitigation of glucose intolerance, adiposity and body weight gain irrespective of treatment with live or pasteurized bacteria. The metabolic benefits were independent of the adaptive immune system, but they were abolished by an inhibitor of M2 polarization in mice. P. faecium directly promoted M2-macrophage polarization through TLR2 signalling and these effects seemed to be independent of gut microbiota changes. Overall, we identify a previously undescribed gut commensal bacterium that could help mitigate obesity and metabolic comorbidities by retuning the innate immune response to hypercaloric diets.

Macronutrients as Regulators of Intestinal Epithelial Permeability: Where Do We Stand?

The intestinal barrier function (IBF) is essential for intestinal homeostasis. Its alterations have been linked to intestinal and systemic disease. Regulation of intestinal permeability is key in the maintenance of the IBF, in which the intestinal epithelium and tight junctions, the mucus layer, sIgA, and antimicrobial peptides are important factors. This review addresses the concept of IBF, focusing on permeability, and summarizes state-of-the-art information on how starvation and macronutrients regulate it. Novel mechanisms regulate intestinal permeability, like its induction by the normal process of nutrient absorption, the contribution of starvation-induced autophagy, or the stimulation of sIgA production by high-protein diets in a T-cell-independent fashion. In addition, observations evidence that starvation and protein restriction increase intestinal permeability, compromising mucin, antimicrobial peptides, and/or intestinal sIgA production. Regarding specific macronutrients, substantial evidence indicates that casein (compared to other protein sources), specific protein-derived peptides and glutamine reinforce IBF. Dietary carbohydrates regulate intestinal permeability in a structure- and composition-dependent fashion; fructose, glucose, and sucrose increase it, while nondigestible oligosaccharides (NDOs) decrease it. Among NDOs, human milk oligosaccharides (HMOs) stand as a promising tool. NODs effects are mediated by intestinal microbiota modulation, production of short-chain fatty acids, and direct interactions with intestinal cells. Finally, evidence supports avoiding high-fat diets for their detrimental effects on IBF. Most studies have been carried out in vitro or in animal models. More information is needed from clinical studies to substantiate beneficial effects and the use of macronutrients in the treatment and prevention of IBF-related diseases.

The Evolving Role of Macrophage Metabolic Reprogramming in Obesity

Recent research has extensively explored the critical role of energy metabolism in shaping the inflammatory response and polarization of macrophages in obesity. This rapidly growing field emphasizes the need to understand the connection between metabolic processes that support macrophage polarization in obesity. Although most published research in this area has focused on glucose and fatty acids, how the flux through other metabolic pathways (such as ketone and amino acid oxidation) in macrophages is altered in obesity is not well defined. This review summarizes the main alterations in uptake, storage, and oxidation of oxidative substrates (glucose, fatty acids, ketone bodies, and amino acids) in macrophages and how these alterations are linked to macrophage polarization and contribution to augmented inflammatory markers in obesity. The review also discusses how oxidative substrates could modulate macrophage energy metabolism and inflammatory responses via feeding into other nonoxidative pathways (such as the pentose phosphate pathway, triacylglycerol synthesis/accumulation), via acting as signalling molecules, or via mediating post-translational modifications (such as O-GlcNAcylation or β-hydroxybutyrylation). The review also identifies several critical unanswered questions regarding the characteristics (functional and metabolic) of macrophages from different origins (adipose tissue, skeletal muscle, bone marrow) in obesity and how these characteristics contribute to early vs late phases of obesity. We also identified a number of new therapeutic targets that could be evaluated in future investigations. Targeting macrophage metabolism in obesity is an exciting and active area of research with significant potential to help identify new treatments to limit the detrimental effects of inflammation in obesity.

A Self-Assembled Metabolic Regulator Reprograms Macrophages to Combat Cytokine Storm and Boost Sepsis Immunotherapy

Sepsis, a life-threatening inflammatory disorder characterized by multiorgan failure, arises from a dysregulated immune response to infection. Modulating macrophage polarization has emerged as a promising strategy to control sepsis-associated inflammation. The endogenous metabolite itaconate has shown anti-inflammatory potential by suppressing the stimulator of interferon genes (STING) pathway, but its efficacy is inhibited by hyperactive glycolysis, which sustains macrophage overactivation. Here, we revealed a critical crosstalk between the itaconate-STING axis and glycolysis in macrophage-mediated inflammation. Building on this interplay, we developed a novel nanoparticle LDO (lonidamine disulfide 4-octyl-itaconate), a self-assembled metabolic regulator integrating an itaconate derivative with the glycolysis inhibitor Lonidamine. By concurrently targeting glycolysis and STING pathways, LDO reprograms macrophages to restore balanced polarization. In sepsis models, LDO effectively attenuates CCL2-driven cytokine storms, alleviates acute lung injury, and significantly enhances survival via metabolic reprogramming. This study offers a cytokine-regulatory strategy rooted in immunometabolism, providing a foundation for the translational development of immune metabolite-based sepsis therapies.

Intestinal IL-25 prevents high-fat diet-induced obesity by modulating the cholesterol transporter NPC1L1 expression in the intestinal epithelial cells

The intestine is essential for digestion and nutrient absorption, and its altered function contributes to metabolic dysregulation and obesity-induced intestinal inflammation. Intestinal immune responses have been associated with the regulation of metabolic dysfunction during obesity. Given that the epithelial cell-derived cytokine IL-25 has been demonstrated to regulate metabolic disorders, we sought to examine the role of intestinal IL-25 in modulating a high-fat diet (HFD)-induced obesity. We found that mice on a high-fat diet exhibited decreased IL-25 expression in the small intestine. Intestinal IL-25 mRNA levels displayed an inverse association with plasma triglycerides, total cholesterol, glucose levels, and the expression of the cholesterol transporter Npc1l1 in the intestine. In HFD-induced obesity, transgenic mice overexpressing IL-25 in the intestinal epithelial cells demonstrated diminished mRNA expression of intestinal genes related to glucose, cholesterol, and fat absorption, along with chylomicron production, while also systemically decreasing plasma glucose, total cholesterol, and triglyceride levels, fat accumulation, and weight gain. In vitro, IL-25 treatment of human intestinal Caco-2 cells directly decreased cholesterol uptake and downregulated the expression of NPC1L1 and its transcriptional regulator, SREBP2. These findings highlight IL-25 as a potential modulator in the intestine that regulates intestinal cholesterol absorption and systemic metabolism in obesity.

New insights into DEHP-induced inflammatory injury in chicken spleen: ROS/TLR4/MyD88 pathway and apoptosis/necroptosis-M1 polarization crosstalk

The environmental endocrine disruptor di(2-ethylhexyl) phthalate (DEHP) is a plasticiser used in large quantities in plastics and is hazardous to the health of humans and various animals. DEHP can be immunotoxic to the spleen through oxidative stress. Still, the role of splenic macrophage polarization in lymphocyte apoptosis and necroptosis, whether they interact with each other, and the mechanism of the effect on splenic inflammatory injury are unknown. In this study, based on the construction of a time-and dose-dependent model of DEHP-exposed chicken spleen, chicken lymphoma cell (MSB-1) and chicken macrophage (HD11) models were established to investigate the mechanism of apoptosis/necroptosis-M1 polarization crosstalk in DEHP-induced toxicity in chicken spleen injury. The results showed that DEHP exposure activated the ROS/TLR4/MyD88 pathway, up-regulated the expression of chemokines, induced macrophage M1 polarization, caused apoptosis and necroptosis in lymphocytes and inflicted inflammatory damage to the spleen, however, these effects could be alleviated by NAC. DEHP exposure of the HD11/MSB-1 cell co-culture system showed that M1 polarization promoted apoptosis and necroptosis and vice versa. In conclusion, DEHP exposure is involved in mediating the crosstalk between apoptosis/necroptosis and M1 polarization through the activation of the ROS/TLR4/MyD88 pathway, which in turn exacerbates inflammatory injury in the chicken spleen.

An update and overview of the various health-related benefits of probiotics: A focus on clinical trials demonstrating efficacy, tolerability and use in patients with impaired glucose tolerance and type 2 diabetes

Recently, probiotics have been investigated as potential therapeutic agents for various diseases. Clinical studies using probiotics have been conducted in humans with impaired glucose tolerance and type 2 diabetes mellitus. Chronic inflammation plays a pivotal role in initiating insulin resistance in the pathogenesis of type 2 diabetes, leading to cardiovascular diseases. Intestinal dysfunction and inflammation have been postulated to trigger systemic chronic inflammation, and it is assumed that the suppression of inflammation in the intestine is the point of activity of probiotics. Therefore, in this review, among the randomised controlled trials that evaluated the effects of probiotics in patients with impaired glucose tolerance and type 2 diabetes, we selected trials that evaluated the indices of glycaemic control and inflammation-related markers. Some trials have shown that the probiotics administration improved glycaemic indices, such as HbA1c levels, and reduced C-reactive protein levels and proinflammatory cytokines, such as IL-6, in the blood, suggesting the suppression of inflammation. Two trials showed improvements in glycaemic indices, implying that they were mediated by IL-10, an anti-inflammatory cytokine. Although a correlation between the suppression of inflammation by probiotics and improvement in glycaemic control has not been documented, one trial revealed that glycaemic control worsened, accompanied by a decrease in anti-inflammatory cytokine levels, after probiotics were discontinued. Other studies have shown that probiotics can reduce blood endotoxin levels and increase intestinal mucin production. These findings suggest that probiotic administration has enormous potential to suppress chronic inflammation in metabolic disorders, leading to improved glycaemic control. Suppression of chronic inflammation has been speculated to prevent vascular diseases in type 2 diabetes.

Isoschaftoside in Fig Leaf Tea Alleviates Nonalcoholic Fatty Liver Disease in Mice via the Regulation of Macrophage Polarity

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a subset of fatty liver disease that is not caused by alcohol or viruses, and its increasing incidence presents a major global health concern. As few pharmacotherapies are available for NAFLD, lifestyle modifications, including diet and exercise, serve as the foundation for treatment. Therefore, NAFLD prevention is more important than cure, emphasizing the need for drugs with excellent safety and long-term efficacy. Fig leaf tea contains rutin and isoschaftoside (ISS), which may possess anti-inflammatory properties. Therefore, the aim of this murine-model-based study was to investigate the potential benefits of fig leaf tea in alleviating NAFLD and to determine the underlying mechanism by gene expression analysis.

RESULTS

We found that in mice with NAFLD induced by a high-fat diet, the administration of high concentration fig leaf tea or 50 µM ISS significantly ameliorated lobule inflammation. In contrast, low concentration fig leaf tea containing 75 µM ISS did not improve inflammation. The balance between the NAFLD-promoting component of fig leaf tea and the inhibitory effect of ISS was thought to be affected. Gene expression analysis of the liver showed that high concentration fig leaf tea or ISS significantly suppressed the expression of M1 macrophage markers such as CD antigens, toll-like receptors (TLR), chemokines, and cytokines. Further, ISS suppressed the amount of TNF-α released during the M1 polarization of macrophage cells upon lipopolysaccharide (LPS) stimulation.

CONCLUSIONS

Overall, these results suggest that controlling macrophage polarization may improve NAFLD. Furthermore, these findings highlight the potential clinical applicability of ISS.

Obesity Promotes Marrow-Derived Myeloid Cell Accumulation While Exercise Reduces Proliferative Signaling in Colon Cancer

PURPOSE

Obesity increases colon cancer risk that has been previously linked to marrow-derived myeloid cells. We previously demonstrated that exercise training (EX) prevents colon cancer initiation, potentially through reduced myelopoiesis. However, it remains unknown whether early myeloid cell accumulation and inflammation in the colon precedes carcinogenesis with high-fat diet (HFD)-induced obesity, and if EX can attenuate these effects. We hypothesized that obesity would promote colon carcinogenesis that was preceded by myeloid cell accumulation and inflammation that would be attenuated by EX.

METHODS

C57BL/6 mice were randomized to a HFD or control (CON) diet for 8 weeks. The HFD mice switched to CON diet and all mice were given intraperitoneal injections of azoxymethane (AOM) to induce colon cancer and randomized into EX or sedentary (SED) conditions.

RESULTS

HFD mice developed more aberrant crypt foci (ACF), a marker for early carcinogenesis, compared with CON ( P < 0.01), and EX developed fewer ACF compared with SED ( P < 0.0001). Marrow-derived ( P < 0.001) CD206 + macrophages were elevated in HFD compared with CON at study week 16 ( P < 0.01). Marrow-derived CD206 - macrophages ( P < 0.05) and marrow-derived ( P < 0.05) CD206 + macrophages were more abundant in HFD compared with CON at study week 42. EX did not alter colon immune cell populations. β-catenin protein was higher in HFD compared with CON at study week 42 ( P < 0.05), and STAT3 protein content was lower at study week 28 with EX compared with SED ( P < 0.05).

CONCLUSIONS

The results suggest that obesity promotes colon ACF formation, potentially through early inflammatory myeloid cell accumulation. Despite attenuating ACF, EX did not alter myeloid cell accumulation in the colon, suggesting that EX inhibits ACF formation through alternative mechanisms which may include reduced β-catenin and STAT3 signaling.

Modulation of gut microbiota, up-regulation of ZO-1, and promotion of metabolism as therapeutic mechanisms of indole-3-carbinol against obesity in mice

Background

Indole-3-carbinol (I3C) is a compound derived from Cruciferous vegetables. We aim to ascertain whether I3C mediates the relations between mouse gut microbiota, intestinal barrier function, and metabolism to treat obesity in mice.

Methods

The experimental analyses focused on the changes in lipid distribution, inflammatory cytokines, glucose tolerance, gut microbiota composition, and serum metabolomics of 60 C57BL/6N mice.

Results

The experimental results demonstrated that I3C reduced body weight, hepatic steatosis, and systemic inflammation and improved insulin resistance in mice on a high-fat diet (HFD). Furthermore, I3C remarkably enhanced the enrichment of probiotics Akkermansia and Ligilactobacillus as well as SCFA-producing bacteria (Eubacterium, Lactococcus, and Coprococcus), while reducing the abundance of Eisenbergiella and Rikenellaceae_RC9_gut_group. Also, I3C notably up-regulated the levels of Claudin4, Occludin, and ZO-1 proteins and modulated the metabolism of argininosuccinic acid and galactose.

Conclusion

The aforementioned findings suggest that I3C exerts a significant anti-obesity effect in mice by regulating abnormal gut microbiome, enhancing intestinal barrier function, and improving metabolic disorders.

ROS-mediated M1 polarization-necroptosis crosstalk involved in Di-(2-ethylhexyl) phthalate-induced chicken liver injury

The widespread use of plasticizers poses a serious threat to the environment and poultry health. Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer that can cause liver damage with prolonged exposure. Oxidative stress is closely associated with DEHP toxicity. Macrophage polarization plays an important role in many physiological and pathological processes and regulates disease development. This study aims to elucidate the mechanism of chronic DEHP exposure leading to chicken liver injury through oxidative stress-induced M1 polarization-necroptosis. In this study, the DEHP exposure model of chicken liver and the single and co-culture model of LMH and HD11 cells were established. With increasing dose and time, DEHP decreased body weight, increased liver coefficient, raised activities of liver function indicators and caused pathological liver damage in chickens. Further studies revealed the increase of reactive oxygen species (ROS) level and malonaldehyde (MDA) content, and the decrease of total antioxidant capacity (T-AOC) level, total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities, which led to excessive oxidative stress in the liver. In addition, there was increased infiltration of liver macrophages (CD68), upregulation of M1 polarization indicators (CD86, iNOS, IL-1β, TNF-α) and downregulation of M2 polarization indicators (CD163, Arg-1, IL-10, TGF-β) and appearance of necroptosis (RIPK1, RIPK3, MLKL). The vitro experiments confirmed the addition of N-acetylcysteine (NAC) inhibited M1 polarization and necroptosis. Besides, M1 polarization of HD11 cells promoted necroptosis of LMH cells in the HD11-LMH co-culture system. In brief, ROS-mediated M1 polarization-necroptosis is involved in DEHP-induced liver injury. This study provides a reference for environmental toxicant exposure in livestock and poultry farming.

Brd4 modulates metabolic endotoxemia-induced inflammation by regulating colonic macrophage infiltration in high-fat diet-fed mice

High-fat diet (HFD) induces low-grade chronic inflammation, contributing to obesity and insulin resistance. However, the precise mechanisms triggering obesity-associated metabolic inflammation remain elusive. In this study, we identified epigenetic factor Brd4 as a key player in this process by regulating the expression of Ccr2/Ccr5 in colonic macrophage. Upon 4-week HFD, myeloid-lineage-specific Brd4 deletion (Brd4-CKO) mice showed reduced colonic inflammation and macrophage infiltration with decreased expression of Ccr2 and Ccr5. Mechanistically, Brd4 was recruited by NF-κB to the enhancer regions of Ccr2 and Ccr5, promoting enhancer RNA expression, which facilitated Ccr2/Ccr5 expression and macrophage migration. Furthermore, decreased infiltration of Ccr2/Ccr5-positive colonic macrophages in Brd4-CKO mice altered gut microbiota composition and reduced intestinal permeability, thereby lowering metabolic endotoxemia. Finally, Brd4-CKO mice subjected to a 4-week LPS infusion exhibited restored susceptibility to HFD-induced obesity and insulin resistance. This study identifies Brd4 as a critical initiator of colonic macrophage-mediated inflammation and metabolic endotoxemia upon HFD, suggesting Brd4 as a potential target for mitigating HFD-induced inflammation, obesity, and its metabolic complications.

The effect of abnormal lipid metabolism on immunosenescence of the colonic lamina propria in mice of different ages

Immunosenescence is an age-associated change in immunological function. The intestinal mucosal immune system is considered the largest immune system in the human body, and its immunosenescence is closely related to the occurrence and development of many diseases. In recent years, studies have identified a crucial correlation between abnormal lipid metabolism induced by high-fat diet (HFD) and immunity, but the effect and mechanism of HFD on colonic mucosal immunosenescence are still unclear. In this study, we established an abnormal lipid metabolism model at different ages by feeding male wild-type mice HFD and compared the immunosenescence of the spleen, which reflects systemic immunity, and the colonic lamina propria (LP), which reflects local immunity. The results showed that HFD could lead to abnormal lipid metabolism at different ages, accelerate systemic and local immunosenescence, and increase the expression of inflammatory factors in colonic tissue. The levels of abnormal biochemical indicators induced by HFD were closely related to the proportions of T cell subsets associated with immunosenescence. Overall, the results showed that HFD had the most significant impact on aged mice. This study provides new ideas for further understanding the relationship between abnormal lipid metabolism and intestinal mucosal immunosenescence.

Induction of a distinct macrophage population and protection from lung injury and fibrosis by Notch2 blockade

Macrophages are pleiotropic and diverse cells that populate all tissues of the body. Besides tissue-specific resident macrophages such as alveolar macrophages, Kupffer cells, and microglia, multiple organs harbor at least two subtypes of other resident macrophages at steady state. During certain circumstances, like tissue insult, additional subtypes of macrophages are recruited to the tissue from the monocyte pool. Previously, a recruited macrophage population marked by expression of Spp1, Cd9, Gpnmb, Fabp5, and Trem2, has been described in several models of organ injury and cancer, and has been linked to fibrosis in mice and humans. Here, we show that Notch2 blockade, given systemically or locally, leads to an increase in this putative pro-fibrotic macrophage in the lung and that this macrophage state can only be adopted by monocytically derived cells and not resident alveolar macrophages. Using a bleomycin and COVID-19 model of lung injury and fibrosis, we find that the expansion of these macrophages before lung injury does not promote fibrosis but rather appears to ameliorate it. This suggests that these damage-associated macrophages are not, by themselves, drivers of fibrosis in the lung.

Sexual Dimorphism in the Immunometabolic Role of Gpr183 in Mice

Context

Excessive eating and intake of a Western diet negatively affect the intestinal immune system, resulting in compromised glucose homeostasis and lower gut bacterial diversity. The G protein-coupled receptor GPR183 regulates immune cell migration and intestinal immune response and has been associated with tuberculosis, type 1 diabetes, and inflammatory bowel diseases.

Objective

We hypothesized that with these implications, GPR183 has an important immunometabolic role and investigated this using a global Gpr183 knockout mouse model.

Methods

Wild-type (WT) and Gpr183-deficient (Gpr183-/-) mice were fed a high-fat, high-sucrose diet (HFSD) for 15 weeks. We investigated changes in weight, body composition, fecal immunoglobulin A (IgA) levels, fecal microbiome, and glucose tolerance before and after the diet. Macrophage infiltration into visceral fat was determined by flow cytometry, and hepatic gene expression was measured.

Results

A sexual dimorphism was discovered, whereby female Gpr183-/- mice showed adverse metabolic outcomes compared to WT counterparts with inferior glucose tolerance, lower fecal IgA levels, and increased macrophage infiltration in visceral fat. In contrast, male Gpr183-/- mice had significantly lower fasting blood glucose after diet than male WT mice. Liver gene expression showed reduced inflammation and macrophage markers in Gpr183-/- livers, regardless of sex, while the pancreatic islet area did not differ between the groups. No conclusive differences were found after microbiome sequencing.

Conclusion

Gpr183 maintains metabolic homeostasis in female but not in male mice independent of diet. If confirmed in humans, future therapy targeting GPR183 should consider this sexual dimorphism.

Traditional medicine Xianglian pill suppresses high-fat diet-related colorectal cancer via inactivating TLR4/MyD88 by remodeling gut microbiota composition and bile acid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Previous studies have revealed that a high-fat diet (HFD) promotes the progression of colorectal cancer (CRC) in close association with disturbances in the intestinal flora and metabolic disorders. Xianglian pill (XLP) is a well-established traditional prescription with unique advantages in controlling intestinal flora imbalance and inflammation. However, its therapeutic effects on HFD-related CRC remain largely unknown.

AIM OF THE STUDY

The primary objective of this research was to investigate the anticancer mechanism of XLP in countering HFD-related CRC.

MATERIALS AND METHODS

The protective effect of XLP was evaluated using azoxymethane (AOM) and dextran sulfate sodium (DSS)-induced CRC model of mice exposed to a HFD. The degree of colorectal carcinogenesis, including body weight, colon length, and histopathology, was measured in mice treated with XLP and untreated mice. The effect of XLP on gut microbiota and its metabolites was detected using 16S rDNA and liquid chromatography/mass spectrometry analysis. Furthermore, a "pseudo-sterile" mouse model was constructed using antibiotics (Abx) to verify whether the gut microbiota and metabolites play a role in the pathogenesis of CRC.

RESULTS

XLP inhibited colorectal tumorigenesis in a dose-dependent fashion. Our findings also highlighted that XLP protected the integrity of the intestinal barrier by reducing the expression of pro-inflammatory cytokines, such as IL-6 and TNF-α, as well as the infiltration of pro-inflammatory macrophages. Mechanistically, XLP inhibited the TLR4/MyD88 pathway. Notably, the XLP treatment increased the proportion of probiotics (particularly Akkermansia) and significantly reduced fecal deoxycholic acid (DCA), a microbiota-derived metabolite of bile acids (BA) closely related to Muribaculaceae. Furthermore, after Abx treatment, XLP showed no clear antitumor effects on CRC. Simultaneously, DCA-supplemented feedings promoted colorectal tumorigenesis and provoked obvious colonic inflammation, M1 macrophage infiltration, and colonic injury. In vitro, the results of RAW-264.7 macrophages and normal intestinal epithelial cells treated with DCA corroborated our in vivo findings, demonstrating consistent patterns in inflammatory responses and intestinal barrier protein expression.

CONCLUSION

Our findings suggest that XLP inhibits colorectal cancer associated with HFD via inactivating TLR4/MyD88 by remodeling gut microbiota composition and BA metabolism.

High-fat diet promotes type 2 diabetes mellitus by disrupting gut microbial rhythms and short-chain fatty acid synthesis

Diabetes ranks among the top 10 causes of death globally, with over 90% of individuals diagnosed with diabetes having type 2 diabetes mellitus (T2DM). It is acknowledged that a high-fat diet (HFD) poses a serious risk for T2DM. The imbalance of intestinal flora, mediated by HFD, can potentially exacerbate the onset and progression of T2DM. However, the impact of HFD on pathological indicators and the intestinal microbiome in the development of T2DM has not been systematically investigated. Therefore, a HFD mouse model and a T2DM mouse model were established, respectively, in this study. The role of HFD as a driving factor in the development of T2DM was assessed using various measures, including basic pathological indicators of T2DM, lipid metabolism, liver oxidative stress, intestinal permeability, levels of inflammatory factors, gut microbiota, and short-chain fatty acids (SCFAs). The findings indicated that HFD could influence the aforementioned measures to align with T2DM changes, but the contribution of HFD varied across different pathological metrics of T2DM. The impact of HFD on low-density lipoprotein cholesterol, glutathione peroxidase, malondialdehyde, and tumor necrosis factor-α did not show a statistically significant difference from those observed in T2DM during its development. In addition, regarding gut microbes, HFD primarily influenced the alterations in bacteria capable of synthesizing SCFAs. The notable decrease in SCFA content in both serum and cecal matter further underscored the effect of HFD on SCFA-synthesising bacteria in mice. Hence, this research provided a systematic assessment of HFD's propelling role in T2DM's progression. It was inferred that gut microbes, particularly those capable of synthesizing SCFAs, could serve as potential targets for the future prevention and treatment of T2DM instigated by HFD.

Deciphering the complex interplay of obesity, epithelial barrier dysfunction, and tight junction remodeling: Unraveling potential therapeutic avenues

Obesity stands as a formidable global health challenge, predisposing individuals to a plethora of chronic illnesses such as cardiovascular disease, diabetes, and cancer. A confluence of genetic polymorphisms, suboptimal dietary choices, and sedentary lifestyles significantly contribute to the elevated incidence of obesity. This multifaceted health issue profoundly disrupts homeostatic equilibrium at both organismal and cellular levels, with marked alterations in gut permeability as a salient consequence. The intricate mechanisms underlying these alterations have yet to be fully elucidated. Still, evidence suggests that heightened inflammatory cytokine levels and the remodeling of tight junction (TJ) proteins, particularly claudins, play a pivotal role in the manifestation of epithelial barrier dysfunction in obesity. Strategic targeting of proteins implicated in these pathways and metabolites such as short-chain fatty acids presents a promising intervention for restoring barrier functionality among individuals with obesity. Nonetheless, recognizing the heterogeneity among affected individuals is paramount; personalized medical interventions or dietary regimens tailored to specific genetic backgrounds and allergy profiles may prove indispensable. This comprehensive review delves into the nexus of obesity, tight junction remodeling, and barrier dysfunction, offering a critical appraisal of potential therapeutic interventions.

Obesity-induced inflammation: connecting the periphery to the brain

Obesity is often associated with a chronic, low-grade inflammatory state affecting the entire body. This sustained inflammatory state disrupts the coordinated communication between the periphery and the brain, which has a crucial role in maintaining homeostasis through humoural, nutrient-mediated, immune and nervous signalling pathways. The inflammatory changes induced by obesity specifically affect communication interfaces, including the blood-brain barrier, glymphatic system and meninges. Consequently, brain areas near the third ventricle, including the hypothalamus and other cognition-relevant regions, become susceptible to impairments, resulting in energy homeostasis dysregulation and an elevated risk of cognitive impairments such as Alzheimer's disease and dementia. This Review explores the intricate communication between the brain and the periphery, highlighting the effect of obesity-induced inflammation on brain function.

Ursolic acid targets secreted phosphoprotein 1 to regulate Th17 cells against metabolic dysfunction-associated steatotic liver disease

BACKGROUND/AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become an increasingly important health challenge, with a substantial rise linked to changing lifestyles and global obesity. Ursolic acid, a natural pentacyclic triterpenoid, has been explored for its potential therapeutic effects. Given its multifunctional bioactive properties, this research further revealed the pharmacological mechanisms of ursolic acid on MASLD.

METHODS

Drug target chips and bioinformatics analysis were combined in this study to explore the potential therapeutic effects of ursolic acid on MASLD. Molecular docking simulations, surface plasmon resonance analyses, pull-down experiments, and co-immunoprecipitation assays were used to verify the direct interactions. Gene knockdown mice were generated, and high-fat diets were used to validate drug efficacy. Furthermore, initial CD4+ T cells were isolated and stimulated to demonstrate our findings.

RESULTS

In this study, the multifunctional extracellular matrix phosphorylated glycoprotein secreted phosphoprotein 1 (SPP1) was investigated, highlighting its capability to induce Th17 cell differentiation, amplifying inflammatory cascades, and subsequently promoting the evolution of MASLD. In addition, this study revealed that in addition to the canonical TGF-β/IL-6 cytokine pathway, SPP1 can directly interact with ITGB1 and CD44, orchestrating Th17 cell differentiation via their joint downstream ERK signaling pathway. Remarkably, ursolic acid intervention notably suppressed the protein activity of SPP1, suggesting a promising avenue for ameliorating the immunoinflammatory trajectory in MASLD progression.

CONCLUSION

Ursolic acid could improve immune inflammation in MASLD by modulating SPP1-mediated Th17 cell differentiation via the ERK signaling pathway, which is orchestrated jointly by ITGB1 and CD44, emerging as a linchpin in this molecular cascade.

Nutrition, gastrointestinal microorganisms and metabolites in mastitis occurrence and control

Mastitis affects almost all mammals including humans and dairy cows. In the dairy industry, bovine mastitis is a disease with a persistently high incidence, causing serious losses to the health of cows, the quality of dairy products, and the economy of dairy farms. Although local udder infection caused by the invasion of exogenous pathogens into the mammary gland was considered the main cause of mastitis, evidence has been established and continues to grow, showing that nutrition factors and gastrointestinal microbiome (GM) as well as their metabolites are also involved in the development of mammary inflammatory response. Suboptimal nutrition is recognized as a risk factor for increased susceptibility to mastitis in cattle, in particular the negative energy balance. The majority of data regarding nutrition and bovine mastitis involves micronutrients. In addition, the dysbiotic GM can directly trigger or aggravate mastitis through entero-mammary gland pathway. The decreased beneficial commensal bacteria, lowered bacterial diversity, and increased pathogens as well as proinflammatory metabolites are found in both the milk and gastrointestinal tract of mastitic dairy cows. This review discussed the relationship between the nutrition (energy and micronutrient levels) and mastitis, summarized the role of GM and metabolites in regulating mastitis. Meanwhile, several non-antibiotics strategies were provided for the prevention and alleviation of mastitis, including micronutrients, probiotics, short-chain fatty acids, high-fiber diet, inulin, and aryl hydrocarbon receptor.

Alleviation of hepatic insulin resistance and steatosis with NMN via improving endoplasmic reticulum-Mitochondria miscommunication in the liver of HFD mice

The interaction between endoplasmic reticulum (ER) and mitochondria has been shown to play a key role in hepatic steatosis during chronic obesity. β-nicotinamide mononucleotide (NMN) has been reported to regulate obesity, however, its molecular mechanism at the subcellular level remains unclear. Here, NMN improved liver steatosis and insulin resistance in chronic high-fat diet (HFD) mice. RNA-seq showed that compared with the liver of HFD mice, NMN intervention enhanced fat digestion and absorption and stimulated the cholesterol metabolism signaling pathways, while impaired insulin resistance and the fatty acid biosynthesis signaling pathways. Mechanistically, NMN ameliorated mitochondrial dysfunction and ER oxidative stress in the liver of HFD mice by increasing hepatic nicotinamide adenine dinucleotide (NAD+) (P < 0.01) levels. This effect increased the contact sites (mitochondria-associated membranes [MAMs]) between ER and mitochondria, thereby promoting intracellular ATP (P < 0.05) production and mitigating lipid metabolic disturbances in the liver of HFD mice. Taken together, this study provided a theoretical basis for restoring metabolic dynamic equilibrium in the liver of HFD mice by increasing MAMs via the nutritional strategy of NMN supplementation.

Ingesting probiotic yogurt containing Lactiplantibacillus plantarum OLL2712 improves glycaemic control in adults with prediabetes in a randomized, double-blind, placebo-controlled trial

AIM

The ingestion of Lactiplantibacillus plantarum OLL2712 (OLL2712) cells has been shown to improve glucose metabolism by suppressing chronic inflammation in murine models and clinical studies. This study aimed to clarify the effect of OLL2712 on glycaemic control in healthy adults with prediabetes.

MATERIALS AND METHODS

The study was a randomized, double-blind, placebo-controlled, parallel-group design. Adult participants with prediabetes [n = 148, glycated haemoglobin (HbA1c) range: 5.6%-6.4%, age range: 20-64 years] were assigned randomly to placebo or OLL2712 groups (n = 74/group) and administered daily for 12 weeks either conventional yogurt or yogurt containing >5 × 109 heat-treated OLL2712 cells, respectively. In addition, the participants were followed for 8 weeks after the discontinuation of either yogurt. The primary outcome was the changes in HbA1c levels at weeks 12 and 16 by analysis of covariance.

RESULTS

The levels of HbA1c and glycoalbumin decreased significantly in both groups at week 12 in comparison with those at week 0, but only in the OLL2712 group at week 16. HbA1c levels decreased significantly at weeks 12 and 16 in the OLL2712 group in comparison with the placebo group (p = .014 and p = .006, respectively). No significant inter- and intragroup differences in HbA1c levels were observed at week 20.

CONCLUSIONS

The ingestion of OLL2712 prevents the deterioration of glycaemic control and maintains the HbA1c levels within the normal range in adults with prediabetes; yogurt probably exhibits similar effects, which may contribute to reducing the risk of developing type 2 diabetes.

Intestinal heat shock proteins in metabolic syndrome: Novel mediators of obesity and its comorbidities resolution after metabolic surgery

Over the past 40 years, the prevalence of obesity has risen dramatically, reaching epidemic proportions. Metabolic surgery has proven to be highly effective in treating obesity, leading to significant improvements or complete resolution of obesity-related comorbidities. Research conducted in both animals and humans suggests that the metabolic benefits achieved through metabolic surgery cannot be solely attributed to weight loss. Indeed, there has been an increasing recognition of intestinal inflammation as a novel factor influencing obesity. The gastrointestinal tract is continuously exposed to dietary components, particularly diets rich in saturated fats, which are known to contribute to obesity. It is now widely accepted that heat shock proteins can be released from various cells including intestinal epithelial cells and act as proinflammatory signals. Several studies have shown that circulating levels of glucose-regulated protein 78 (GRP78) are increased in subjects with obesity and correlate with the severity of the disease. Moreover, mice with a partial knockout of GRP78 are protected from diet-induced obesity. In this review, we discuss the role of GRP78 in the development of obesity. Several evidence suggests that GRP78 can influence adipogenesis, lipid droplets stabilization, insulin resistance, and liver steatosis. We also provide an update on GRP78 regulation following metabolic surgery, focusing on the bypass of the small intestine as a key factor for GRP78 secretion. Finally, we discuss the potential role of monoclonal antibodies against GRP78 as a treatment for obesity.

Escherichia coli NF73-1 disrupts the gut-vascular barrier and aggravates high-fat diet-induced fatty liver disease via inhibiting Wnt/β-catenin signalling pathway

BACKGROUND & AIMS

Gut-vascular barrier (GVB) dysfunction has been shown to be a prerequisite for nonalcoholic fatty liver disease (NAFLD) development. However, the causes of GVB disruption and the underlying mechanisms are still elusive. Here, we explored whether and how Escherichia coli (E. coli) NF73-1, a pathogenic E. coli strain isolated from nonalcoholic steatohepatitis patients, contributes to NAFLD by modulating the GVB.

METHODS

C57BL/6J mice were fed with high-fat diet (HFD) or normal diet in the presence or absence of E. coli NF73-1 for the indicated time periods. Intestinal barrier function and infiltration of immune cells were evaluated in these mice. Endothelial cells were exposed to E. coli NF73-1 for barrier integrity analysis.

RESULTS

HFD-induced GVB disruption preceded the damage of intestinal epithelial barrier (IEB) as well as intestinal and hepatic inflammatory changes and can be reversed by vascular endothelial growth factor A blockade. Antibiotic treatment prevented mice from HFD-induced liver steatosis by restoration of the GVB. Notably, E. coli NF73-1 caused a more conspicuous damage of GVB than that of the IEB and contributed to NAFLD development. Mechanistically, E. coli NF73-1 dismantled the GVB by inhibiting the Wnt/β-catenin signalling pathway. Activation of Wnt/β-catenin improved the GVB and impeded the translocation of E. coli NF73-1 into the liver in vitro and in vivo.

CONCLUSIONS

E. coli NF73-1 disrupts GVB and aggravates NAFLD via inhibiting the Wnt/β-catenin signalling pathway. Targeting E. coli NF73-1 or selectively enhancing the GVB may act as potential avenues for the prevention and treatment of NAFLD.

Dietary Intake of Fructooligosaccharides Protects against Metabolic Derangements Evoked by Chronic Exposure to Fructose or Galactose in Rats

SCOPE

Diets rich in fat and sugars evoke chronic low-grade inflammation, leading to metabolic derangements. This study investigates the impact of fructose and galactose, two commonly consumed simple sugars, on exacerbation of the harmful effects caused by high fat intake. Additionally, the potential efficacy of fructooligosaccharides (FOS), a fermentable dietary fiber, in counteracting these effects is examined.

METHODS AND RESULTS

Male Sprague-Dawley rats (six/group) are fed 8 weeks as follows: control 5% fat diet (CNT), 20% fat diet (FAT), FAT+10% FOS diet (FAT+FOS), FAT+25% galactose diet (FAT+GAL), FAT+GAL+10% FOS diet (FAT+GAL+FOS), FAT+25% fructose diet (FAT+FRU), FAT+FRU+10% FOS diet (FAT+FRU+FOS). The dietary manipulations tested do not affect body weight gain, blood glucose, or markers of systemic inflammation whereas significant increases in plasma concentrations of triacylglycerols, cholesterol, aspartate aminotransferase, and alanine aminotrasferase are detected in both FAT+FRU and FAT+GAL compared to CNT. In the liver and skeletal muscle, both sugars induce significant accumulation of lipids and advanced glycation end-products (AGEs). FOS supplementation prevents these impairments.

CONCLUSION

This study extends the understanding of the deleterious effects of a chronic intake of simple sugars and demonstrates the beneficial role of the prebiotic FOS in dampening the sugar-induced metabolic impairments by prevention of lipid and AGEs accumulation.

Dengyinnaotong attenuates atherosclerotic lesions, gut dysbiosis and intestinal epithelial barrier impairment in the high fat diet-fed ApoE-/- mice

ETHNOPHARMACOLOGICAL RELEVANCE

Dengyinnaotong (DYNT) is a traditional Chinese medicine-based patent drug officially approved for the treatment of ischemic stroke primarily based on its indigenous application for the treatment of cardiovascular and cerebrovascular diseases in Southwest China. Atherosclerosis is the principal pathology underlying the pathogenesis of ischemic stroke and coronary artery disease. However, whether DYNT is effective at mitigating atherosclerosis remains unknown.

AIMS OF THE STUDY

The purpose of the current study is to evaluate the potential impact of DYNT treatment on the atherosclerotic lesions and associated pathological mechanisms.

MATERIALS AND METHODS

Histological, immunohistochemical, molecular biological approaches were adopted to investigate the pharmacological impact of DYNT treatment on atherosclerosis and associated pathophysiological alterations in the high fat diet (HFD)-fed ApoE gene deficient (ApoE-/-) mice.

RESULTS

DYNT treatment reduced the size of the atherosclerotic plaques, alleviated the necrotic core, lowered the lipid retention, mitigated the macrophagic burden and decreased the expression of proatherogenic chemokine Ccl2 in the atherosclerotic lesions. DYNT treatment also offered partial protection against atherogenic dyslipidemia and mitigated hepatic lipid content as well as fatty liver pathologies in the HFD-fed ApoE-/- mice. Furthermore, DYNT treatment protected against atherosclerosis-associated gut dysbiosis and impairment in the intestinal epithelial barrier.

CONCLUSIONS

Our work provides novel preclinical evidence that underpins the multifaceted effects of DYNT in the control of atherosclerosis.

Nutritional regulation of microbiota-derived metabolites: Implications for immunity and inflammation

Nutrition profoundly shapes immunity and inflammation across the lifespan of mammals, from pre- and post-natal periods to later life. Emerging insights into diet-microbiota interactions indicate that nutrition has a dominant influence on the composition-and metabolic output-of the intestinal microbiota, which in turn has major consequences for host immunity and inflammation. Here, we discuss recent findings that support the concept that dietary effects on microbiota-derived metabolites potently alter immune responses in health and disease. We discuss how specific dietary components and metabolites can be either pro-inflammatory or anti-inflammatory in a context- and tissue-dependent manner during infection, chronic inflammation, and cancer. Together, these studies emphasize the influence of diet-microbiota crosstalk on immune regulation that will have a significant impact on precision nutrition approaches and therapeutic interventions for managing inflammation, infection, and cancer immunotherapy.

Yogurt starter strains ameliorate intestinal barrier dysfunction via activating AMPK in Caco-2 cells

Lactic acid bacteria (LAB) are commonly used probiotics that improve human health in various aspects. We previously reported that yogurt starter strains, Lactobacillus delbrueckii subsp. bulgaricus 2038 and Streptococcus thermophilus 1131, potentially enhance the intestinal epithelial barrier function by inducing the expression of antimicrobial peptides in the small intestine. However, their effects on physical barrier functions remain unknown. In this study, we found that both strains ameliorated the decreased trans-epithelial resistance and the increased permeability of fluorescein isothiocyanate-dextran induced by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in Caco-2 cells. We also demonstrated that LAB prevented a decrease in the expression and disassembly of tight junctions (TJs) induced by TNF-α and IFN-γ. To assess the repair activity of TJs, a calcium switch assay was performed. Both strains were found to promote the reassembly of TJs, and their activity was canceled by the inhibitor of AMP-activated protein kinase (AMPK). Moreover, these strains showed increased AMPK phosphorylation. These observations suggest that the strains ameliorated physical barrier dysfunction via the activation of AMPK. The activities preventing barrier destruction induced by TNF-α and IFN-γ were strain-dependent. Several strains containing L. bulgaricus 2038 and S. thermophilus 1131 significantly suppressed the barrier impairment, and L. bulgaricus 2038 showed the strongest activity among them. Our findings suggest that the intake of L. bulgaricus 2038 and S. thermophilus 1131 is a potential strategy for the prevention and repair of leaky gut.

Small intestinal CaSR-dependent and CaSR-independent protein sensing regulates feeding and glucose tolerance in rats

Proteins activate small intestinal calcium sensing receptor (CaSR) and/or peptide transporter 1 (PepT1) to increase hormone secretion1-8, but the effect of small intestinal protein sensing and the mechanistic potential of CaSR and/or PepT1 in feeding and glucose regulation remain inconclusive. Here we show that, in male rats, CaSR in the upper small intestine is required for casein infusion to increase glucose tolerance and GLP1 and GIP secretion, which was also dependent on PepT1 (ref. 9). PepT1, but not CaSR, is required for casein infusion to lower feeding. Upper small intestine casein sensing fails to regulate feeding, but not glucose tolerance, in high-fat-fed rats with decreased PepT1 but increased CaSR expression. In the ileum, a CaSR-dependent but PepT1-independent pathway is required for casein infusion to lower feeding and increase glucose tolerance in chow-fed rats, in parallel with increased PYY and GLP1 release, respectively. High fat decreases ileal CaSR expression and disrupts casein sensing on feeding but not on glucose control, suggesting an ileal CaSR-independent, glucose-regulatory pathway. In summary, we discover small intestinal CaSR- and PepT1-dependent and -independent protein sensing mechanisms that regulate gut hormone release, feeding and glucose tolerance. Our findings highlight the potential of targeting small intestinal CaSR and/or PepT1 to regulate feeding and glucose tolerance.

Impact of Daikenchuto (TU-100) on the early postoperative period in duodenal-jejunal bypass

INTRODUCTION

We investigated the effect of Daikenchuto (TU-100) on the early postoperative period in duodenal-jejunal bypass (DJB).

METHODS

Study 1:The effect of TU-100 on diabetic rats was investigated. Rats were sacrificed after receiving TU-100 for one week. Study 2:The effect of TU-100 on DJB was investigated. Rats in the DJB and TU-100 treated DJB groups were sacrificed 24 hours postoperation to evaluate blood glucose, cytokine expression, and gut microbiome.

RESULTS

Study 1:TU-100 did not affect glucose or body weight. TU-100 suppressed intestinal inflammation and modified the gut microbiome. Specifically, Bifidobacterium and Blautia were increased, and Turicibacter were decreased in this group. Study 2:Both DJB and TU-100 treated DJB rats showed lower blood glucose at 24 hours postoperation than at preoperation. Cytokine expression in the liver and small intestine of the TU-100 treated DJB group was significantly lower than that of the DJB group. The gut microbiome composition in TU-100 treated DJB rats was altered. In particular, Bifidobacterium and Blautia were increased in this group.

CONCLUSION

DJB suppressed blood glucose during the early postoperative period. TU-100 may enhance the anti-diabetic effect of metabolic surgery by changing the gut microbiome and suppressing inflammation in the early postoperative period. J. Med. Invest. 71 : 210-218, August, 2024.

Natto consumption suppresses atherosclerotic plaque progression in LDL receptor-deficient mice transplanted with iRFP-expressing hematopoietic cells

Natto, known for its high vitamin K content, has been demonstrated to suppress atherosclerosis in large-scale clinical trials through a yet-unknown mechanism. In this study, we used a previously reported mouse model, transplanting the bone marrow of mice expressing infra-red fluorescent protein (iRFP) into LDLR-deficient mice, allowing unique and non-invasive observation of foam cells expressing iRFP in atherosclerotic lesions. Using 3 natto strains, we meticulously examined the effects of varying vitamin K levels on atherosclerosis in these mice. Notably, high vitamin K natto significantly reduced aortic staining and iRFP fluorescence, indicative of decreased atherosclerosis. Furthermore, mice administered natto showed changes in gut microbiota, including an increase in natto bacteria within the cecum, and a significant reduction in serum CCL2 expression. In experiments with LPS-stimulated macrophages, adding natto decreased CCL2 expression and increased anti-inflammatory cytokine IL-10 expression. This suggests that natto inhibits atherosclerosis through suppression of intestinal inflammation and reduced CCL2 expression in macrophages.

TMT-Based Proteomics Analysis Revealed the Protein Changes in Perirenal Fat from Obese Rabbits

Obesity has become increasingly prevalent in recent years, and there is a need for a deeper understanding of the complex pathogenesis underlying the obesity condition. Therefore, the objective of this study was to investigate how a high-fat diet (HFD) affects protein expression in a female-rabbit model compared to a standard normal-diet group (SND), to gain comprehensive insights into the molecular mechanisms involved in obesity. To achieve this objective, a tandem mass tag (TMT)-based quantitative proteomics analysis was conducted to examine the molecular changes occurring in the white adipose tissue (WAT) from the HFD and SND groups. The sequencing results identified a total of 4215 proteins, among which 151 proteins exhibited significant differential expression. Specifically, there were 85 upregulated proteins and 66 downregulated proteins in the HFD group compared to the SND group. Further analysis of these differentially expressed proteins (DEPs) revealed their involvement in crucial biological processes, including energy metabolism, hormonal regulation, and inflammatory response. In conclusion, this study sheds light on the impact of HFD on protein expression in a female-rabbit model, providing new insights into the molecular mechanisms underlying obesity and the associated metabolic disorders.

Dectin-2 Deficiency Promotes Proinflammatory Cytokine Release From Macrophages and Impairs Insulin Secretion

Pancreatic islet inflammation plays a crucial role in the etiology of type 2 diabetes (T2D). Macrophages residing in pancreatic islets have emerged as key players in islet inflammation. Macrophages express a plethora of innate immune receptors that bind to environmental and metabolic cues and integrate these signals to trigger an inflammatory response that contributes to the development of islet inflammation. One such receptor, Dectin-2, has been identified within pancreatic islets; however, its role in glucose metabolism remains largely unknown. Here we have demonstrated that mice lacking Dectin-2 exhibit local inflammation within islets, along with impaired insulin secretion and β-cell dysfunction. Our findings indicate that these effects are mediated by proinflammatory cytokines, such as interleukin (IL)-1α and IL-6, which are secreted by macrophages that have acquired an inflammatory phenotype because of the loss of Dectin-2. This study provides novel insights into the mechanisms underlying the role of Dectin-2 in the development of islet inflammation.

Metabolic and functional remodeling of colonic macrophages in response to high-fat diet-induced obesity

Little is known about the effects of high-fat diet (HFD)-induced obesity on resident colonic lamina propria (LP) macrophages (LPMs) function and metabolism. Here, we report that obesity and diabetes resulted in increased macrophage infiltration in the colon. These macrophages exhibited the residency phenotype CX3CR1hiMHCIIhi and were CD4-TIM4-. During HFD, resident colonic LPM exhibited a lipid metabolism gene expression signature that overlapped that used to define lipid-associated macrophages (LAMs). Via single-cell RNA sequencing, we identified a sub-cluster of macrophages, increased in HFD, that were responsible for the LAM signature. Compared to other macrophages in the colon, these cells were characterized by elevated glycolysis, phagocytosis, and efferocytosis signatures. CX3CR1hiMHCIIhi colonic resident LPMs had fewer lipid droplets (LDs) and decreased triacylglycerol (TG) content compared to equivalent cells in lean mice and exhibited increased phagocytic capacity, suggesting that HFD induces adaptive responses in LPMs to limit bacterial translocation.

Gut microbial metabolite deoxycholic acid facilitates Th17 differentiation through modulating cholesterol biosynthesis and participates in high-fat diet-associated colonic inflammation

BACKGROUND

High-fat diet (HFD) is closely associated with the increased prevalence of inflammatory bowel disease (IBD). Excessive gut microbial metabolite deoxycholic acid (DCA) caused by HFD plays significant roles in eliciting intestinal inflammation, however, the mechanism underlining the induction of inflammatory response by DCA has not been fully elucidated. The purpose of this study was to investigate the role of DCA in the triggering of inflammation via affecting CD4+ T cell differentiation.

RESULTS

Murine CD4+T cells were cultured under Th1, Th2 or Th17-polarizing conditions treated with or without different dosage of DCA, and flowcytometry was conducted to detect the effect of DCA on CD4+ T cell differentiation. Alteration of gene expression in CD4+ T cells upon DCA treatment was determined by RNA-sequencing and qRT-PCR. Bioinformatic analysis, cholesterol metabolic profiling, ChIP assay and immuno-fluorescent staining were further applied to explore the DCA-regulated pathway that involved in CD4+T cell differentiation. The results showed that DCA could dose-dependently promote the differentiation of CD4+ T cell into Th17 linage with pathogenic signature. Mechanistically, DCA stimulated the expression of cholesterol biosynthetic enzymes CYP51 and led to the increased generation of endogenous RORγt agonists, including zymosterol and desmosterol, therefore facilitating Th17 differentiation. Up-regulation of CYP51 by DCA was largely mediated via targeting transcription factor SREBP2 and at least partially through bile acid receptor TGR5. In addition, DCA-supplemented diet significantly increased intestinal Th17 cell infiltration and exacerbated TNBS-induced colitis. Administration of cholestyramine to eliminate fecal bile acid obviously alleviated colonic inflammation accompanied by decreased Th17 cells in HFD-fed mice.

CONCLUSIONS

Our data establish a link between DCA-induced cholesterol biosynthesis in immune cells and gut inflammation. Modulation of bile acid level or targeting cholesterol metabolic pathway may be potential therapeutic measurements for HFD-related colitis.

The intestinal immune system and gut barrier function in obesity and ageing

Obesity and ageing predispose to numerous, yet overlapping chronic diseases. For example, metabolic abnormalities, including insulin resistance (IR) and type 2 diabetes (T2D) are important causes of morbidity and mortality. Low-grade chronic inflammation of tissues, such as the liver, visceral adipose tissue and neurological tissues, is considered a significant contributor to these chronic diseases. Thus, it is becoming increasingly important to understand what drives this inflammation in affected tissues. Recent evidence, especially in the context of obesity, suggests that the intestine plays an important role as the gatekeeper of inflammatory stimuli that ultimately fuels low-grade chronic tissue inflammation. In addition to metabolic diseases, abnormalities in the intestinal mucosal barrier have been linked to a range of other chronic inflammatory conditions, such as neurodegeneration and ageing. The flow of inflammatory stimuli from the gut is in part controlled by local immunological inputs impacting the intestinal barrier. Here, we will review the impact of obesity and ageing on the intestinal immune system and its downstream consequences on gut barrier function, which is strongly implicated in the pathogenesis of obesity and age-related diseases. In particular, we will discuss the effects of age-related intestinal dysfunction on neurodegenerative diseases.

Tumour-associated macrophages in gastric cancer: From function and mechanism to application

BACKGROUND

Gastric cancer (GC) is a malignant tumour, with high morbidity and mortality rates worldwide. The occurrence and development of GC is a complex process involving genetic changes in tumour cells and the influence of the surrounding tumour microenvironment (TME). Accumulative evidence shows that tumour-associated macrophages (TAMs) play a vital role in GC, acting as plentiful and active infiltrating inflammatory cells in the TME.

MAIN BODY

In this review, the different functions and mechanisms of TAMs in GC progression, including the conversion of phenotypic subtypes; promotion of tumour proliferation, invasion and migration; induction of chemoresistance; promotion of angiogenesis; modulation of immunosuppression; reprogramming of metabolism; and interaction with the microbial community are summarised. Although the role of TAMs in GC remains controversial in clinical settings, clarifying their significance in the treatment selection and prognostic prediction of GC could support optimising TAM-centred clinicaltherapy.

CONCLUSION

In summary, we reviewed the the phenotypic polarisation, function and molecular mechanism of TAMs and their potential applications in the treatment selection and prognostic prediction of GC.

Diesel Exhaust Particle (DEP)-induced glucose intolerance is driven by an intestinal innate immune response and NLRP3 activation in mice

BACKGROUND

We previously found that air pollution particles reaching the gastrointestinal tract elicit gut inflammation as shown by up-regulated gene expression of pro-inflammatory cytokines and monocyte/macrophage markers. This inflammatory response was associated with beta-cell dysfunction and glucose intolerance. So far, it remains unclear whether gut inflammatory changes upon oral air pollution exposure are causally linked to the development of diabetes. Hence, our aim was to assess the role of immune cells in mediating glucose intolerance instigated by orally administered air pollutants.

METHODS

To assess immune-mediated mechanisms underlying air pollution-induced glucose intolerance, we administered diesel exhaust particles (DEP; NIST 1650b, 12 µg five days/week) or phosphate-buffered saline (PBS) via gavage for up to 10 months to wild-type mice and mice with genetic or pharmacological depletion of innate or adaptive immune cells. We performed unbiased RNA-sequencing of intestinal macrophages to elucidate signaling pathways that could be pharmacologically targeted and applied an in vitro approach to confirm these pathways.

RESULTS

Oral exposure to air pollution particles induced an interferon and inflammatory signature in colon macrophages together with a decrease of CCR2^- anti-inflammatory/resident macrophages. Depletion of macrophages, NLRP3 or IL-1β protected mice from air pollution-induced glucose intolerance. On the contrary, Rag2-/- mice lacking adaptive immune cells developed pronounced gut inflammation and glucose intolerance upon oral DEP exposure.

CONCLUSION

In mice, oral exposure to air pollution particles triggers an immune-mediated response in intestinal macrophages that contributes to the development of a diabetes-like phenotype. These findings point towards new pharmacologic targets in diabetes instigated by air pollution particles.

Identification of the hub genes in polycystic ovary syndrome based on disease-associated molecule network

Revealing the key genes involved in polycystic ovary syndrome (PCOS) and elucidating its pathogenic mechanism is of extreme importance for the development of targeted clinical therapy for PCOS. Investigating disease by integrating several associated and interacting molecules in biological systems will make it possible to discover new pathogenic genes. In this study, an integrative disease-associated molecule network, combining protein-protein interactions and protein-metabolites interactions (PPMI) network was constructed based on the PCOS-associated genes and metabolites systematically collected. This new PPMI strategy identified several potential PCOS-associated genes, which have unreported in previous publications. Moreover, the systematic analysis of five benchmarks data sets indicated the DERL1 was identified as downregulated in PCOS granulosa cell and has good classification performance between PCOS patients and healthy controls. CCR2 and DVL3 were upregulated in PCOS adipose tissues and have good classification performance. The expression of novel gene FXR2 identified in this study is significantly increased in ovarian granulosa cells of PCOS patients compared with controls via quantitative analysis. Our study uncovers substantial differences in the PCOS-specific tissue and provides a plethora of information on dysregulated genes and metabolites that are linked to PCOS. This knowledgebase could have the potential to benefit the scientific and clinical community. In sum, the identification of novel gene associated with PCOS provides valuable insights into the underlying molecular mechanisms of PCOS and could potentially lead to the development of new diagnostic and therapeutic strategies.

A Short-Term High-Fat Diet Worsens Insulin Sensitivity with Changes in Metabolic Parameters in Non-Obese Japanese Men

A short-term high-calorie high-fat diet (HCHFD) impairs insulin sensitivity in non-obese South Asian but not Caucasian men; however, the effect of short-term HCHFD on insulin sensitivity in East Asians is unknown. We recruited 21 healthy non-obese Japanese men to evaluate metabolic parameters and gut microbiota before and after 6-day HCHFD consisting of a regular diet plus a 45% energy excess with dairy fat supplementation. We evaluated tissue-specific insulin sensitivity and metabolic clearance rate of insulin (MCRI) using a two-step hyperinsulinemic euglycemic clamp, glucose tolerance using the glucose tolerance test, and measured ectopic fat in muscle and the liver using ¹H-magnetic resonance spectroscopy. The primary outcome of this study was insulin sensitivity measured by the clamp study. The secondary/exploratory outcomes were other metabolic changes. After HCHFD, levels of circulating lipopolysaccharide binding protein (LBP), a marker of endotoxemia, increased by 14%. In addition, intramyocellular lipid levels in the tibialis anterior and soleus and intrahepatic lipid levels increased by 47%, 31%, and 200%, respectively. Insulin sensitivity decreased by 4% in muscle and 8% in liver. However, even with reduced insulin sensitivity, glucose metabolism was maintained by increased serum insulin concentrations due to lower MCRI and higher endogenous insulin secretion during the clamp. Glucose levels during the meal tolerance test were comparable before and after HCHFD. In conclusion, short-term HCHFD impaired insulin sensitivity in the muscle and livers of non-obese Japanese men with increased LBP and ectopic fat accumulation. Elevated insulin levels from modulated insulin secretion and clearance might contribute to the maintenance of normal glucose metabolism during the clamp and meal tolerance test.

Lactiplantibacillus plantarum OLL2712 Induces Autophagy via MYD88 and Strengthens Tight Junction Integrity to Promote the Barrier Function in Intestinal Epithelial Cells

Autophagy is an important system conserved in eukaryotes that maintains homeostasis by degrading abnormal proteins. Autophagy incompetence in intestinal epithelial cells causes the abnormal function of intestinal stem cells and other cells and damages intestinal barrier function. The disruption of the intestinal barrier causes chronic inflammation throughout the body, followed by impaired glucose and lipid metabolism. Lactiplantibacillus plantarum OLL2712 (OLL2712) is a lactic acid bacterium that induces interleukin-10 production from immune cells, alleviates chronic inflammation, and improves glucose and lipid metabolism. In this study, we hypothesized that OLL2712 exerts anti-inflammatory effects by inducing autophagy and ameliorating intestinal barrier dysfunction, and we investigated its autophagy-inducing activities and functions. Caco-2 cells stimulated with OLL2712 for 24 h showed an increased number of autolysosomes per cell, compared with unstimulated cells. Therefore, the permeability of fluorescein isothiocyanate dextran 4000 (FD-4) was suppressed by inducing autophagy. In contrast, mucin secretion in HT-29-MTX-E12 cells was also increased by OLL2712 but not via autophagy induction. Finally, the signaling pathway involved in autophagy induction by OLL2712 was found to be mediated by myeloid differentiation factor 88 (MYD88). In conclusion, our findings suggest that OLL2712 induces autophagy in intestinal epithelial cells via MYD88, and that mucosal barrier function is strengthened by inducing autophagy.

Mechanism of immune attack in the progression of obesity-related type 2 diabetes

Obesity and overweight are widespread issues in adults, children, and adolescents globally, and have caused a noticeable rise in obesity-related complications such as type 2 diabetes mellitus (T2DM). Chronic low-grade inflammation is an important promotor of the pathogenesis of obesity-related T2DM. This proinflammatory activation occurs in multiple organs and tissues. Immune cell-mediated systemic attack is considered to contribute strongly to impaired insulin secretion, insulin resistance, and other metabolic disorders. This review focused on highlighting recent advances and underlying mechanisms of immune cell infiltration and inflammatory responses in the gut, islet, and insulin-targeting organs (adipose tissue, liver, skeletal muscle) in obesity-related T2DM. There is current evidence that both the innate and adaptive immune systems contribute to the development of obesity and T2DM.

Diet-induced obesity alters intestinal monocyte-derived and tissue-resident macrophages and increases intestinal permeability in female mice independent of tumor necrosis factor

Macrophages are essential for homeostatic maintenance of the anti-inflammatory and tolerogenic intestinal environment, yet monocyte-derived macrophages can promote local inflammation. Proinflammatory macrophage accumulation within the intestines may contribute to the development of systemic chronic inflammation and immunometabolic dysfunction in obesity. Using a model of high-fat diet-induced obesity in C57BL/6J female mice, we assessed intestinal paracellular permeability by in vivo and ex vivo assays and quantitated intestinal macrophages in ileum and colon tissues by multicolor flow cytometry after short (6 wk), intermediate (12 wk), and prolonged (18 wk) diet allocation. We characterized monocyte-derived CD4^-TIM4^- and CD4⁺TIM4^- macrophages, as well as tissue-resident CD4⁺TIM4⁺ macrophages. Diet-induced obesity had tissue- and time-dependent effects on intestinal permeability, as well as monocyte and macrophage numbers, surface marker phenotype, and intracellular production of the cytokines IL-10 and tumor necrosis factor (TNF). We found that obese mice had increased paracellular permeability, in particular within the ileum, but this did not elicit recruitment of monocytes nor a local proinflammatory response by monocyte-derived or tissue-resident macrophages in either the ileum or colon. Proliferation of monocyte-derived and tissue-resident macrophages was also unchanged. Wild-type and TNF^-/- littermate mice had similar intestinal permeability and macrophage population characteristics in response to diet-induced obesity. These data are unique from reported effects of diet-induced obesity on macrophages in metabolic tissues, as well as outcomes of acute inflammation within the intestines. These experiments also collectively indicate that TNF does not mediate effects of diet-induced obesity on paracellular permeability or intestinal monocyte-derived and tissue-resident intestinal macrophages in young female mice.NEW & NOTEWORTHY We found that diet-induced obesity in female mice has tissue- and time-dependent effects on intestinal paracellular permeability as well as monocyte-derived and tissue-resident macrophage numbers, surface marker phenotype, and intracellular production of the cytokines IL-10 and TNF. These changes were not mediated by TNF.

Interactions between Intestinal Homeostasis and NAD+ Biology in Regulating Incretin Production and Postprandial Glucose Metabolism

The intestine has garnered attention as a target organ for developing new therapies for impaired glucose tolerance. The intestine, which produces incretin hormones, is the central regulator of glucose metabolism. Glucagon-like peptide-1 (GLP-1) production, which determines postprandial glucose levels, is regulated by intestinal homeostasis. Nicotinamide phosphoribosyltransferase (NAMPT)-mediated nicotinamide adenine dinucleotide (NAD⁺) biosynthesis in major metabolic organs such as the liver, adipose tissue, and skeletal muscle plays a crucial role in obesity- and aging-associated organ derangements. Furthermore, NAMPT-mediated NAD⁺ biosynthesis in the intestines and its upstream and downstream mediators, adenosine monophosphate-activated protein kinase (AMPK) and NAD⁺-dependent deacetylase sirtuins (SIRTs), respectively, are critical for intestinal homeostasis, including gut microbiota composition and bile acid metabolism, and GLP-1 production. Thus, boosting the intestinal AMPK-NAMPT-NAD⁺-SIRT pathway to improve intestinal homeostasis, GLP-1 production, and postprandial glucose metabolism has gained significant attention as a novel strategy to improve impaired glucose tolerance. Herein, we aimed to review in detail the regulatory mechanisms and importance of intestinal NAMPT-mediated NAD⁺ biosynthesis in regulating intestinal homeostasis and GLP-1 secretion in obesity and aging. Furthermore, dietary and molecular factors regulating intestinal NAMPT-mediated NAD⁺ biosynthesis were critically explored to facilitate the development of new therapeutic strategies for postprandial glucose dysregulation.

Pathophysiology of Prediabetes, Diabetes, and Diabetic Remission in Cats

Diabetes mellitus (DM) has a heterogenous cause, and the exact pathogenesis differs between patients. Most diabetic cats have a cause similar to human type 2 DM but, in some, DM is associated with underlying conditions, such as hypersomatotropism, hyperadrenocorticism, or administration of diabetogenic drugs. Predisposing factors for feline DM include obesity, reduced physical activity, male sex, and increasing age. Gluco(lipo)toxicity and genetic predisposition also likely play roles in pathogenesis. Prediabetes cannot be accurately diagnosed in cats at the current time. Diabetic cats can enter remission, but relapses are common, as these cats might have ongoing, abnormal glucose homeostasis.

Fatty acid overproduction by gut commensal microbiota exacerbates obesity

Although recent studies have highlighted the impact of gut microbes on the progression of obesity and its comorbidities, it is not fully understood how these microbes promote these disorders, especially in terms of the role of microbial metabolites. Here, we report that Fusimonas intestini, a commensal species of the family Lachnospiraceae, is highly colonized in both humans and mice with obesity and hyperglycemia, produces long-chain fatty acids such as elaidate, and consequently facilitates diet-induced obesity. High fat intake altered the expression of microbial genes involved in lipid production, such as the fatty acid metabolism regulator fadR. Monocolonization with a FadR-overexpressing Escherichia coli exacerbated the metabolic phenotypes, suggesting that the change in bacterial lipid metabolism is causally involved in disease progression. Mechanistically, the microbe-derived fatty acids impaired intestinal epithelial integrity to promote metabolic endotoxemia. Our study thus provides a mechanistic linkage between gut commensals and obesity through the overproduction of microbe-derived lipids.

Sleeve gastrectomy decreases high-fat diet induced colonic pro-inflammatory status through the gut microbiota alterations

Background

High-fat diet (HFD) induced obesity is characterized with chronic low-grade inflammation in various tissues and organs among which colon is the first to display pro-inflammatory features associated with alterations of the gut microbiota. Sleeve gastrectomy (SG) is currently one of the most effective treatments for obesity. Although studies reveal that SG results in decreased levels of inflammation in multiple tissues such as liver and adipose tissues, the effects of surgery on obesity related pro-inflammatory status in the colon and its relation to the microbial changes remain unknown.

Methods

To determine the effects of SG on the colonic pro-inflammatory condition and the gut microbiota, SG was performed on HFD-induced obese mice. To probe the causal relationship between alterations of the gut microbiota and improvements of pro-inflammatory status in the colon following SG, we applied broad-spectrum antibiotics cocktails on mice that received SG to disturb the gut microbial changes. The pro-inflammatory shifts in the colon were assessed based on morphology, macrophage infiltration and expressions of a variety of cytokine genes and tight junction protein genes. The gut microbiota alterations were analyzed using 16s rRNA sequencing. RNA sequencing of colon was conducted to further explore the role of the gut microbiota in amelioration of colonic pro-inflammation following SG at a transcriptional level.

Results

Although SG did not lead to pronounced changes of colonic morphology and macrophage infiltration in the colon, there were significant decreases in the expressions of several pro-inflammatory cytokines including interleukin-1β (IL-1β), IL-6, IL-18, and IL-23 as well as increased expressions of some tight junction proteins in the colon following SG, suggesting an improvement of pro-inflammatory status. This was accompanied by changing populations of the gut microbiota such as increased richness of Lactobacillus subspecies following SG. Importantly, oral administrations of broad-spectrum antibiotics to delete most intestinal bacteria abrogated surgical effects to relieve colonic pro-inflammation. This was further confirmed by transcriptional analysis of colon indicating that SG regulated inflammation related pathways in a manner that was gut microbiota relevant.

Conclusion

These results support that SG decreases obesity related colonic pro-inflammatory status through the gut microbial alterations.

High-fat diet and estrogen modulate the gut microbiota in a sex-dependent manner in mice

A high-fat diet can lead to gut microbiota dysbiosis, chronic intestinal inflammation, and metabolic syndrome. Notably, resulting phenotypes, such as glucose and insulin levels, colonic crypt cell proliferation, and macrophage infiltration, exhibit sex differences, and females are less affected. This is, in part, attributed to sex hormones. To investigate if there are sex differences in the microbiota and if estrogenic ligands can attenuate high-fat diet-induced dysbiosis, we used whole-genome shotgun sequencing to characterize the impact of diet, sex, and estrogenic ligands on the microbial composition of the cecal content of mice. We here report clear host sex differences along with remarkably sex-dependent responses to high-fat diet. Females, specifically, exhibited increased abundance of Blautia hansenii, and its levels correlated negatively with insulin levels in both sexes. Estrogen treatment had a modest impact on the microbiota diversity but altered a few important species in males. This included Collinsella aerofaciens F, which we show correlated with colonic macrophage infiltration. In conclusion, male and female mice exhibit clear differences in their cecal microbial composition and in how diet and estrogens impact the composition. Further, specific microbial strains are significantly correlated with metabolic parameters.

Orally administered Lactiplantibacillus plantarum OLL2712 decreased intestinal permeability, especially in the ileum: Ingested lactic acid bacteria alleviated obesity-induced inflammation by collaborating with gut microbiota

Introduction

Chronic inflammation caused by dietary obesity has been considered to induce lifestyle-related diseases and functional ingredients with anti-inflammatory effects are attracting attention. Although multiple studies on obesity had proved the anti-inflammatory effects of ingestion of lactic acid bacteria (LAB) and other functional ingredients on adipose tissue, the precise effects on the intestine, especially on the individual intestinal segments have not been made clear. In this study, we elucidated the mechanisms of Lactiplantibacillus plantarum (basonym: Lactobacillus plantarum) OLL2712 in suppressing obesity-induced inflammation using high fat diet (HFD)-fed mice obesity model.

Methods

We orally administered heat-treated LAB to HFD-fed mice model, and investigated the inflammatory changes in adipose tissue and intestinal immune cells. We also analyzed gut microbiota, and evaluated the inflammation and permeability of the duodenum, jejunum, ileum and colon; four intestinal segments differing in gut bacteria composition and immune response.

Results

After 3-week LAB administration, the gene expression levels of proinflammatory cytokines were downregulated in adipose tissue, colon, and Peyer's patches (PP)-derived F4/80⁺ cells. The LAB treatment alleviated obesity-related gut microbiota imbalance. L. plantarum OLL2712 treatment helps maintain intestinal barrier function, especially in the ileum, possibly by preventing ZO-1 and Occludin downregulation.

Discussion

Our results suggest that the oral administration of the LAB strain regulated the gut microbiota, suppressed intestinal inflammation, and improved the gut barrier, which could inhibit the products of obesity-induced gut dysbiosis from translocating into the bloodstream and the adipose tissue, through which the LAB finally alleviated the inflammation caused by dietary obesity. Barrier improvement was observed, especially in the ileum, suggesting collaborative modulation of the intestinal immune responses by ingested LAB and microbiota.