High-fat diet disrupts REG3γ and gut microbial rhythms promoting metabolic dysfunction

Identification and Validation of Circadian Rhythm-Related Genes Involved in Intervertebral Disc Degeneration and Analysis of Immune Cell Infiltration via Machine Learning

Background

Low back pain is a significant burden worldwide, and intervertebral disc degeneration (IVDD) is identified as the primary cause. Recent research has emphasized the significant role of circadian rhythms (CRs) and immunity in affecting intervertebral discs (IVD). However, the influence of circadian rhythms and immunity on the mechanism of IVDD remains unclear. This study aimed to identify and validate key rhythm-related genes in IVDD and analyze their correlation with immune cell infiltration.

Methods

Two gene expression profiles related to IVDD and rhythm-related genes were obtained from the Gene Expression Omnibus and GeneCards databases to identify differentially expressed rhythm-related genes (DERGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA) were conducted to explore the biological functions of these genes. LASSO regression and SVM algorithms were employed to identify hub genes. We subsequently investigated the correlation between hub rhythm-related genes and immune cell infiltration. Finally, nucleus pulposus-derived mesenchymal stem cells (NPMSCs) were isolated from normal and degenerative human IVD tissues. Hub rhythm-related genes expression in NPMSCs was confirmed by real-time quantitative PCR (RT-qPCR).

Results

Six hub genes related to CRs (CCND1, FOXO1, FRMD8, NTRK2, PRRT1, and TFPI) were screened out. Immune infiltration analysis revealed that the IVDD group had significantly more M0 macrophages and significantly fewer follicular helper T cells than those of the control group. Specifically, M0 macrophages were significantly associated with FRMD8, PRRT1, and TFPI. T follicular helper cells were significantly associated with FRDM8, FOXO1, and CCND1. We further confirmed that CCND1, FRMD8, NTRK2, and TFPI were dysrhythmic within NPMSCs from degenerated IVD in vitro.

Conclusion

Six genes (CCND1, FOXO1, FRMD8, NTRK2, PRRT1 and TFPI) linked to circadian rhythms associated with IVDD progression, together with immunity. The identification of these DEGs may provide new insights for the diagnosis and treatment of IVDD.

Effects of self-managed lifestyle behavioral changes on cognitive impairment control in Chinese older adults: a population-based prospective study

Few studies have examined the effects of self-managed lifestyle behavioral adjustment on cognitive status. This study aimed to explore the association between self-managed behavioral changes and transitions in cognitive status. The Hubei Memory and Aging Cohort Study was a prospective cohort study conducted from 2018-2023 in rural and urban areas. Home-dwelling adults aged ≥65 years completed neuropsychological, lifestyle, clinical, and cognitive assessments. The Cox regressions and cubic splines were used to assess the risk of incident cognitive impairment, and latent class analysis was used to group participants based on behavioral patterns and assess transitions in cognitive status. Among 2477 participants with a mean of 2.02 (SD, 1.25) years of follow-up were included in the study. Participants with low and intermediate compared with high baseline behavioral risk exhibited a reduced risk of incident cognitive impairment. At follow-up, those who maintained stable healthy behaviors or positively adjusted them had a 54% (HR, 0.46 [95% CI, 0.34-0.62]) and 84% (0.16 [0.07-0.35]) lower risk of developing cognitive impairment, respectively, compared with those who maintained unhealthy behaviors. The standard and reinforced behavioral adjustment patterns exhibited a 37% (0.63 [0.22-1.79]) and 77% (0.23 [0.05-0.97]) reduction in the risk of incident cognitive impairment, respectively, compared with the basic pattern. Optimal cognitive gains were attributed to positive adjustments in social networks, physical exercise, cognitive activity, and sleep health. Older adults who maintained healthy behaviors or positively adjusted their unhealthy behaviors exhibited a reduced risk of incident cognitive impairment. Positive behavior modification brought greater cognitive improvement to all participants and more pronounced effects for those with dementia.

Loss of diurnal oscillatory rhythms in gut microbiota correlates with progression of atherosclerosis

Circadian rhythms in gut microbiota composition are crucial for metabolic function and disease progression, yet the diurnal oscillation patterns of gut microbiota in atherosclerotic cardiovascular disease (ASCVD) and their role in disease progression remain unknown. Here, we investigated gut bacterial dynamics in Apoe-/- mice over 24 hours and elucidated dynamic changes in fecal microbiota composition and function among C57BL/6 and Apoe-/- mice with standard chow diet or high-fat/high-cholesterol diet under ad libitum conditions. Compared with C57BL/6 mice, Apoe-/- mice exhibited significant differences in fecal microbial composition. Rhythmicity analysis revealed that the temporal dynamics of fecal microbiota composition and function in Apoe-/- mice differed significantly from those in C57BL/6 mice, particularly in B. coccoides-dominated oscillatory modules. Functional annotation showed that rhythmic B. coccoides strains inhibited ASCVD progression by enhancing intestinal and endothelial barrier functions. These findings demonstrate that diurnal oscillations in gut microbiota are closely associated with ASCVD progression and provide new insights for microbiota-targeted precision therapies.

Salvianolic acid B (SalB) improves high-fat diet (HFD)-caused cognitive impairment in mice by modulating the Trem2/Dap12 pathway in vivo and in vitro

Salvianolic acid B (SalB), which extracted from Salvia miltiorrhiza Bunge (Labiatae), is a traditional Chinese medicine. SalB is widely used in nervous system diseases. This study evaluated the protective effect of SalB on high-fat diet (HFD)-induced cognitive impairment and its mechanisms in vivo and in vitro. The behavior tests demonstrated that SalB alleviated motor skills and learning capacity in HFD mice. Animal experiments have confirmed that SalB reduced the mRNA expression of inflammatory markers and the Trem2/Dap12 pathway in HIP. Furthermore, SalB inhibited the microglia Trem2/Dap12 pathway in HIP. In vivo, palmitic acid (PA) was used to intervene in BV2 cells to construct an inflammatory. SalB reduced the mRNA expression of inflammatory markers and inhibited the Trem2/Dap12 pathway in BV2 cells. In conclusion, SalB treatment may serve as a possible therapy for cognitive impairment induced by HFD.

Mitochondrial CCN1 drives ferroptosis via fatty acid β-oxidation

Ferroptosis is a type of oxidative cell death, although its key metabolic processes remain incompletely understood. Here, we employ a comprehensive multiomics screening approach that identified cellular communication network factor 1 (CCN1) as a metabolic catalyst of ferroptosis. Upon ferroptosis induction, CCN1 relocates to mitochondrial complexes, facilitating electron transfer flavoprotein subunit alpha (ETFA)-dependent fatty acid β-oxidation. Compared with a traditional carnitine O-palmitoyltransferase 2 (CPT2)-ETFA pathway, the CCN1-ETFA pathway provides additional substrates for mitochondrial reactive oxygen species production, thereby stimulating ferroptosis through lipid peroxidation. A high-fat diet can enhance the anticancer efficacy of ferroptosis in lung cancer mouse models, depending on CCN1. Furthermore, primary lung cancer cells derived from patients with hypertriglyceridemia or high CCN1 expression demonstrate increased susceptibility to ferroptosis in vitro and in vivo. These findings do not only identify the metabolic role of mitochondrial CCN1 but also establish a strategy for enhancing ferroptosis-based anticancer therapies.

Interactions between Gut Microbiota, Host Circadian Rhythms, and Metabolic Diseases

The circadian rhythm arises endogenously from genetically encoded molecular clocks, wherein the components collaborate to induce cyclic fluctuations, occurring approximately every 24 h. The rhythms synchronize biological processes with regular and predictable environmental patterns to guarantee the host metabolism and energy homeostasis function and well-being. Disruptions to circadian rhythms are widely associated with metabolic disorders. Notably, microbial rhythms are influenced by both the host's intrinsic circadian clock and external rhythmic factors (i.e., light-dark cycle, diet patterns, and diet composition), which affect the structure of microbial communities and metabolic functions. Moreover, microbiota and the metabolites also reciprocally influence host rhythms, potentially impacting host metabolic function. This review aimed to explore the bidirectional interactions between the circadian clock, factors influencing host-microbial circadian rhythms, and the effects on lipid metabolism and energy homeostasis.

Circadian rhythm, hypoxia, and cellular senescence: From molecular mechanisms to targeted strategies

Cellular senescence precipitates a decline in physiological activities and metabolic functions, often accompanied by heightened inflammatory responses, diminished immune function, and impaired tissue and organ performance. Despite extensive research, the mechanisms underpinning cellular senescence remain incompletely elucidated. Emerging evidence implicates circadian rhythm and hypoxia as pivotal factors in cellular senescence. Circadian proteins are central to the molecular mechanism governing circadian rhythm, which regulates homeostasis throughout the body. These proteins mediate responses to hypoxic stress and influence the progression of cellular senescence, with protein Brain and muscle arnt-like 1 (BMAL1 or Arntl) playing a prominent role. Hypoxia-inducible factor-1α (HIF-1α), a key regulator of oxygen homeostasis within the cellular microenvironment, orchestrates the transcription of genes involved in various physiological processes. HIF-1α not only impacts normal circadian rhythm functions but also can induce or inhibit cellular senescence. Notably, HIF-1α may aberrantly interact with BMAL1, forming the HIF-1α-BMAL1 heterodimer, which can instigate multiple physiological dysfunctions. This heterodimer is hypothesized to modulate cellular senescence by affecting the molecular mechanism of circadian rhythm and hypoxia signaling pathways. In this review, we elucidate the intricate relationships among circadian rhythm, hypoxia, and cellular senescence. We synthesize diverse evidence to discuss their underlying mechanisms and identify novel therapeutic targets to address cellular senescence. Additionally, we discuss current challenges and suggest potential directions for future research. This work aims to deepen our understanding of the interplay between circadian rhythm, hypoxia, and cellular senescence, ultimately facilitating the development of therapeutic strategies for aging and related diseases.

The time is now: accounting for time-of-day effects to improve reproducibility and translation of metabolism research

The constant expansion of the field of metabolic research has led to more nuanced and sophisticated understanding of the complex mechanisms that underlie metabolic functions and diseases. Collaborations with scientists of various fields such as neuroscience, immunology and drug discovery have further enhanced the ability to probe the role of metabolism in physiological processes. However, many behaviours, endocrine and biochemical processes, and the expression of genes, proteins and metabolites have daily ~24-h biological rhythms and thus peak only at specific times of the day. This daily variation can lead to incorrect interpretations, lack of reproducibility across laboratories and challenges in translating preclinical studies to humans. In this Review, we discuss the biological, environmental and experimental factors affecting circadian rhythms in rodents, which can in turn alter their metabolic pathways and the outcomes of experiments. We recommend that these variables be duly considered and suggest best practices for designing, analysing and reporting metabolic experiments in a circadian context.

Cross-tissue multi-omics analyses reveal the gut microbiota's absence impacts organ morphology, immune homeostasis, bile acid and lipid metabolism

The gut microbiota influences host immunity and metabolism, and changes in its composition and function have been implicated in several non-communicable diseases. Here, comparing germ-free (GF) and specific pathogen-free (SPF) mice using spatial transcriptomics, single-cell RNA sequencing, and targeted bile acid metabolomics across multiple organs, we systematically assessed how the gut microbiota's absence affected organ morphology, immune homeostasis, bile acid, and lipid metabolism. Through integrated analysis, we detect marked aberration in B, myeloid, and T/natural killer cells, altered mucosal zonation and nutrient uptake, and significant shifts in bile acid profiles in feces, liver, and circulation, with the alternate synthesis pathway predominant in GF mice and pronounced changes in bile acid enterohepatic circulation. Particularly, autophagy-driven lipid droplet breakdown in ileum epithelium and the liver's zinc finger and BTB domain-containing protein (ZBTB20)-Lipoprotein lipase (LPL) (ZBTB20-LPL) axis are key to plasma lipid homeostasis in GF mice. Our results unveil the complexity of microbiota-host interactions in the crosstalk between commensal gut bacteria and the host.

Circadian metabolic adaptations to infections

Circadian clocks are biological oscillators that evolved to coordinate rhythms in behaviour and physiology around the 24-hour day. In mammalian tissues, circadian rhythms and metabolism are highly intertwined. The clock machinery controls rhythmic levels of circulating hormones and metabolites, as well as rate-limiting enzymes catalysing biosynthesis or degradation of macromolecules in metabolic tissues, such control being exerted both at the transcriptional and post-transcriptional level. During infections, major metabolic adaptation occurs in mammalian hosts, at the level of both the single immune cell and the whole organism. Under these circumstances, the rhythmic metabolic needs of the host intersect with those of two other players: the pathogen and the microbiota. These three components cooperate or compete to meet their own metabolic demands across the 24 hours. Here, we review findings describing the circadian regulation of the host response to infection, the circadian metabolic adaptations occurring during host-microbiota-pathogen interactions and how such regulation can influence the immune response of the host and, ultimately, its own survival.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

The gut microbiome, immune modulation, and cognitive decline: insights on the gut-brain axis

The gut microbiome has emerged as a pivotal area of research due to its significant influence on the immune system and cognitive functions. Cognitive disorders, including dementia and Parkinson's disease, represent substantial global health challenges. This review explores the relationship between gut microbiota, immune modulation, and cognitive decline, with a particular focus on the gut-brain axis. Research indicates that gut bacteria produce metabolites, including short-chain fatty acids (SCFAs), which affect mucosal immunity, antigen presentation, and immune responses, thereby influencing cognitive functions. A noteworthy correlation has been identified between imbalances in the gut microbiome and cognitive impairments, suggesting novel pathways for the treatment of cognitive disorders. Additionally, factors such as diet, environment, and pharmaceuticals play a role in shaping the composition of the gut microbiome, subsequently impacting both immune and cognitive health. This article aims to clarify the complex interactions among gut microbiota, immune regulation, and cognitive disorders, evaluating their potential as therapeutic targets. The goal is to promote microbiome-based treatments and lay the groundwork for future research in this field.

Chronic restraint stress affects the diurnal rhythms of gut microbial composition and metabolism in a mouse model of depression

BACKGROUND

Depression is a common mental disorder accompanied by gut microbiota dysbiosis, which disturbs the metabolism of the host. While diurnal oscillation of the intestinal microbiota is involved in regulating host metabolism, the characteristics of the intestinal microbial circadian rhythm in depression remain unknown. Our aim was to investigate the microbial circadian oscillation signature and related metabolic pathways in a mouse model with depression-like behaviours.

METHODS

Chronic restraint stress (CRS) was used to induce depressive-like behaviours in C57BL/6J mice. The open field test (OFT) and forced swimming test (FST) were used to evaluate anxiety- and depressive-like behaviours in the control and CRS groups. Afterwards, faecal samples from the two groups were collected every four hours from ZT2 (9:00 am) to ZT22 (5:00 am). Faecal 16 S rRNA gene sequencing and metabolomics analysis were performed, and the microbial circadian rhythm was analysed via the MetaCycle package in R/RStudio.

RESULTS

CRS mice exhibited depressive-like behaviours after 4 weeks of restriction. Alpha- and beta-diversity analyses revealed that the microbial composition in control and CRS mice oscillated throughout the day. The circadian rhythm analyses revealed that at the phylum level, Bacteroidota, Firmicutes, Cyanobacteria and Patescibacteria showed circadian rhythmicity in the CRS group. At the genus level, Dubosiella and Romboutsia showed circadian rhythmicity in the control group, and Dubosiella abundance was correlated with tryptophan and galactose metabolism. In the CRS group, Bacteroides, Parabacteroides, and Rikenellaceae_RC9_gut_group showed circadian rhythmicity; among these genera, Parabacteroides was related to tryptophan metabolism, axon regeneration, phenylalanine metabolism and tyrosine metabolism.

CONCLUSION

Our data highlight the importance of observing the diurnal oscillation of the microbiome in host with depressive-like states. Rhythmicity in the microbiome may affect the host by regulating distinct metabolic pathways during the light and dark phases. A better combination of microbiota composition and oscillation would help to offer novel insight into key genera and their potential effects on depression.

Chemical interplay between gut microbiota and epigenetics: Implications in circadian biology

Circadian rhythms are intrinsic molecular mechanisms that synchronize biological functions with the day/night cycle. The mammalian gut is colonized by a myriad of microbes, collectively named the gut microbiota. The microbiota impacts host physiology via metabolites and structural components. A key mechanism is the modulation of host epigenetic pathways, especially histone modifications. An increasing number of studies indicate the role of the microbiota in regulating host circadian rhythms. However, the mechanisms remain largely unknown. Here, we summarize studies on microbial regulation of host circadian rhythms and epigenetic pathways, highlight recent findings on how the microbiota employs host epigenetic machinery to regulate circadian rhythms, and discuss its impacts on host physiology, particularly immune and metabolic functions. We further describe current challenges and resources that could facilitate research on microbiota-epigenetic-circadian rhythm interactions to advance our knowledge of circadian disorders and possible therapeutic avenues.

Depression and obesity: Focus on factors and mechanistic links

Major depressive disorder (MDD) is defined as mood disorder causing a persistent loss of interest and despair for two weeks or greater, with related symptoms. Depression can interfere with daily life and can cause those affected to not work, study, eat, sleep, and enjoy previously enjoyed hobbies and life events as they did previously. If untreated, it can become a serious health condition. Depression is multifactorial with a variety of factors influencing the condition. These factors include: (1) poor diet and exercise, (2) socioeconomic status, (3) gender, (4) biological clocks, (5) genetics and epigenetics, and (6) personal stressors. Treatment of depressive disorders is thus also multifactorial and utilizes the following therapies: (1) diet and exercise, (2) bright light therapy, (3) cognitive behavioral therapy, and (4) pharmaceutical therapy. Obesity is defined as body mass index over 30 and above, is believed to be causally linked to MDD through both psychological and molecular means. Atypical depression, a common form of MDD, is most strongly correlated with a high proclivity for obesity. Obesity and depression have a bidirectional relationship, a patient experiencing either condition singularly is more likely to develop the other due to the neural links between the two, including emotional lability, physical health of the brain, hormones, cytokine secretion, appetite, diet and feeding habits, inflammatory state. In individuals consuming a high fat diet (HFD) commonly ingested by those with obesity, the gut-microbiome is altered leading to systemic inflammation and the dysregulation of mood and the HPA axis impacting their neural health. The purpose of this paper is to examine the interplay of potential molecular, psychological, societal, and environmental causal factors of depressive disorders and how obesity perpetuates depression. A secondary aim of this paper is to examine current interventions that may help improve those affected by both conditions.

Oat anthranilamides regulates high-fat diet-induced intestinal inflammation by the TLR4/NF-κb signalling pathway and gut microbiota

Oat anthranilamides have demonstrated antioxidant and anti-inflammatory effects; however, the precise mechanism of action remains unclear. This study investigated the impact of oat anthranilamide B (AVN B) on high-fat diet (HFD)-induced intestinal inflammation in mice and its underlying mechanisms. The results indicated that AVN B supplementation mitigated weight gain and reduced inflammatory and oxidative stress markers in serum, liver, and intestines. It improved intestinal barrier dysfunction by upregulating the expression levels of Occludin and MUC2 while simultaneously reducing intestinal inflammation by inhibiting the TLR4/NF-κB signalling pathway. Additionally, AVN B treatment improved gut microbiota composition. It increased the abundance of beneficial flora and the production of short-chain fatty acids (SCFAs), especially propionate and butyrate, associated with reduced production of pro-inflammatory factors and enhanced intestinal protection. The findings provide scientific evidence for the potential of AVN B as an anti-inflammatory agent.

The gut microbiota-derived metabolite indole-3-propionic acid enhances leptin sensitivity by targeting STAT3 against diet-induced obesity

Obesity is associated with the gut microbiome. Here, we report that gut commensal Clostridia bacteria regulate host energy balance through the tryptophan-derived metabolite indole-3-propionic acid (IPA). IPA acts as an endogenous leptin sensitiser to counteract obesity. Mechanistically, IPA is secreted from the gut into the circulation, and then targets to the STAT3 in the hypothalamic appetite regulation centre, promoting its phosphorylation and nuclear translocation, which enhances the body's response to leptin, and regulates the balance between appetite and energy metabolism. The in vitro pull-down assays involving site-directed mutagenesis demonstrate that Trp623 in the SH2 domain is the key binding site for STAT3-IPA interaction. High-fat diet (HFD), rather than genetic factors, induces excessive secretion of antimicrobial peptides by Paneth cells, inhibiting the growth of Clostridia in the gut and resulting in decreased production of the beneficial metabolite IPA. IPA or Clostridium sporogenes supplement effectively controls weight gain, improves glucose metabolism, and reduces inflammation in DIO mice. IPA fails to achieve such effects in ob/ob mice, while exogenous leptin administration restores the therapeutic effect of IPA. Our study suggests that the IPA-based gut-brain axis regulates host metabolism, and supplementation with microbiome-derived IPA could be a promising intervention strategy for treating obesity.

The role of organic anion transport peptides in cyclophosphamide-induced hepatotoxicity in high-fat diet mice

Clinically, patients with lipid metabolism disorders caused by factors such as high-fat diet (HFD) developed severer liver damage and lipid metabolism disorders after treatment with cyclophosphamide (CTX). This can lead to elevated levels of inflammatory cytokines, which in turn lead to changes in levels of various liver and kidney transporters, to increase drug accumulation, which may be a way to exacerbate liver injury. The role of organic anion transport peptides (OATPs), an important uptake transporter, in the transport process of CTX and in the aggravation of liver injury induced by CTX in HFD mice is unclear. The aim of this study was to characterize the hepatotoxicity and lipid metabolism disorders of HFD mice exposed to CTX and to investigate the possible mechanism from the perspective of drug in vivo process and transporter regulation. It has been verified that CTX induced severer liver injury in HFD mice compared with the control group, accompanied with upregulated Interleukin-1β (IL-1β) expression and down-regulated OATPs expression in liver and renal, and increased blood CTX concentration. This suggested that the down-regulation of OATPs involved in IL-1β may play an important role in HFD-CTX-induced liver injury, and then experiments in Hep G2 cells was used to validate the hypothesis. Pharmacokinetic and primary hepatocyte uptake experiments confirmed that OATPs may be an important factor involved in the in vivo process of CTX. In summary, this study demonstrated that HFD mice exhibited severer liver toxicity after exposure to CTX, which may be caused by the disorder of lipid levels and the up-regulation of inflammatory factors, and then the downregulation of liver and renal OATPs to increase the accumulation of CTX in vivo. These findings suggest that IL-1β and OATPs may be involved in the interactive regulation of CTX accumulation and endogenous lipid disturbance, and play very important role in the aggravation of liver injury induced by CTX in HFD mice.

Interaction Between Early Meals (Big-Breakfast Diet), Clock Gene mRNA Expression, and Gut Microbiome to Regulate Weight Loss and Glucose Metabolism in Obesity and Type 2 Diabetes

The circadian clock gene system plays a pivotal role in coordinating the daily rhythms of most metabolic processes. It is synchronized with the light-dark cycle and the eating-fasting schedule. Notably, the interaction between meal timing and circadian clock genes (CGs) allows for optimizing metabolic processes at specific times of the day. Breakfast has a powerful resetting effect on the CG network. A misaligned meal pattern, such as skipping breakfast, can lead to a discordance between meal timing and the endogenous CGs, and is associated with obesity and T2D. Conversely, concentrating most calories and carbohydrates (CH) in the early hours of the day upregulates metabolic CG expression, thus promoting improved weight loss and glycemic control. Recently, it was revealed that microorganisms in the gastrointestinal tract, known as the gut microbiome (GM), and its derived metabolites display daily oscillation, and play a critical role in energy and glucose metabolism. The timing of meal intake coordinates the oscillation of GM and GM-derived metabolites, which in turn influences CG expression, playing a crucial role in the metabolic response to food intake. An imbalance in the gut microbiota (dysbiosis) can also reciprocally disrupt CG rhythms. Evidence suggests that misaligned meal timing may cause such disruptions and can lead to obesity and hyperglycemia. This manuscript focuses on the reciprocal interaction between meal timing, GM oscillation, and circadian CG rhythms. It will also review studies demonstrating how aligning meal timing with the circadian clock can reset and synchronize CG rhythms and GM oscillations. This synchronization can facilitate weight loss and improve glycemic control in obesity and those with T2D.

Effects of Low-Carbohydrate and Low-Fat Diets on Morbidity and Mortality of COPD

Purpose

Although low-carbohydrate and low-fat diets improve weight loss, cardiovascular disease, and diabetes, the relationship between these dietary patterns, highlighting macronutrient sources, and chronic obstructive pulmonary disease (COPD) remains unclear. This study aimed to assess the association between low-carbohydrate diets (LCDs) and low-fat diets (LFDs) and the odds of COPD and mortality among people with COPD in the National Health and Nutrition Examination Survey.

Patients and Methods

Clinical data were extracted from the 2007-2008, 2009-2010, and 2011-2012 National Health and Nutrition Examination Survey (NHANES) cycles that met the inclusion criteria. Multivariable logistic regression was used to evaluate the associations between LCD and LFD scores and COPD, and multivariable Cox proportional hazards regression and restricted cubic spline (RCS) regression were used to assess the relationship between all-cause mortality and LCD and LFD scores.

Results

Comparing extreme tertiles, multivariable-adjusted odds ratio (OR) were 1 (reference), 1.09 (95% CI, 0.77-1.55), 1.84 (95% CI, 1.09-3.09) (P = 0.045 for trend) for unhealthy LFD scores. After multivariate adjustment, a per 5-point increase in unhealthy LCD score was associated with a 21% higher risk of total mortality (hazard ratio, 1.21; 95% CI, 1.03-1.43); while a per 5-point increase in healthy LFD scores was associated with a 21% lower risk of total mortality (HR, 0.79; 95% CI, 0.67-0.94).

Conclusion

Higher unhealthy LFD score was associated with an increased odds of COPD. Unhealthy LCD scores were significantly associated with higher total mortality, whereas healthy LFD scores were associated with lower total mortality in patients with COPD.

Dietary-timing-induced gut microbiota diurnal oscillations modulate inflammatory rhythms in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune condition characterized by inflammatory activity with distinct rhythmic fluctuations. However, the precise mechanisms governing these inflammatory rhythms remain elusive. Here, we explore the interaction between dietary patterns, gut microbiota diurnal oscillations, and the rhythmicity of RA in both collagen-induced arthritis (CIA) mice and patients with RA and highlight the significance of dietary timing in modulating RA inflammatory rhythms linked to gut microbiota. Specifically, we discovered that Parabacteroides distasonis (P. distasonis) uses β-glucosidase (β-GC) to release glycitein (GLY) from the diet in response to daily nutritional cues, influencing RA inflammatory rhythms dependent on the sirtuin 5-nuclear factor-κB (SIRT5-NF-κB) axis. Notably, we validated the daily fluctuations of P. distasonis-β-GC-GLY in patients with RA through continuous sampling across day-night cycles. These findings underscore the crucial role of dietary timing in RA rhythmicity and propose potential clinical implications for novel therapeutic strategies to alleviate arthritis.

Circadian disruption in cancer hallmarks: Novel insight into the molecular mechanisms of tumorigenesis and cancer treatment

Circadian rhythms are 24-h rhythms governing temporal organization of behavior and physiology generated by molecular clocks composed of autoregulatory transcription-translation feedback loops (TTFLs). Disruption of circadian rhythms leads to a spectrum of pathologies, including cancer by triggering or being involved in different hallmarks. Clock control of phenotypic plasticity involved in tumorigenesis operates in aberrant dedifferentiating to progenitor-like cell states, generation of cancer stem cells (CSCs) and epithelial-to-mesenchymal transition (EMT) events. Circadian rhythms might act as candidates for regulatory mechanisms of cellular senescent and functional determinants of senescence-associated secretory phenotype (SASP). Reciprocal control between clock and epigenetics sheds light on post-transcriptional regulation of circadian rhythms and opens avenues for novel anti-cancer strategies. Additionally, disrupting circadian rhythms influences microbiota communities that could be associated with altered homeostasis contributing to cancer development. Herein, we summarize recent advances in support of the nexus between disruptions of circadian rhythms and cancer hallmarks of new dimensions, thus providing novel perspectives on potentially effective treatment approaches for cancer management.

Manipulation of feeding patterns in high fat diet fed rats improves microbiota composition dynamics, inflammation and gut-brain signaling

Chronic consumption of high fat (HF) diets has been shown to increase meal size and meal frequency in rodents, resulting in overeating. Reducing meal frequency and establishing periods of fasting, independently of caloric intake, may improve obesity-associated metabolic disorders. Additionally, diet-driven changes in microbiota composition have been shown to play a critical role in the development and maintenance of metabolic disorders. In this study, we used a pair-feeding paradigm to reduce meal frequency and snacking episodes while maintaining overall intake and body weight in HF fed rats. We hypothesized that manipulation of feeding patterns would improve microbiota composition and metabolic outcomes. Male Wistar rats were placed in three groups consuming either a HF, low fat diet (LF, matched for sugar), or pair-fed HF diet for 7 weeks (n = 11-12/group). Pair-fed animals received the same amount of food consumed by the HF fed group once daily before dark onset (HF-PF). Rats underwent oral glucose tolerance and gut peptide cholecystokinin sensitivity tests. Bacterial DNA was extracted from the feces collected during both dark and light cycles and sequenced via Illumina MiSeq sequencing of the 16S V4 region. Our pair-feeding paradigm reduced meal numbers, especially small meals in the inactive phase, without changing total caloric intake. This shift in feeding patterns reduced relative abundances of obesity-associated bacteria and maintained circadian fluctuations in microbial abundances. These changes were associated with improved gastrointestinal (GI) function, reduced inflammation, and improved glucose tolerance and gut to brain signaling. We concluded from these data that targeting snacking may help improve metabolic outcomes, independently of energy content of the diet and hyperphagia.

Akkermansia muciniphila in the small intestine improves liver fibrosis in a murine liver cirrhosis model

Recent evidence indicates that liver cirrhosis (LC) is a reversible condition, but there is no established intervention against liver fibrosis. Although the gut microbiota is considered involved in the pathogenesis of LC, the underlying mechanisms remain unclear. Although the antibiotic, rifaximin (RFX), is effective for hepatic encephalopathy (HE) with LC, the impact of RFX on intestinal bacteria is unknown. We investigated the bacterial compositions along the GI tract under RFX treatment using a murine LC model. RFX improved liver fibrosis and hyperammonemia and altered the bacterial composition in the small intestine. The efficacy of RFX was associated with increases in specific bacterial genera, including Akkermansia. Administration of a commensal strain of Akkermansia muciniphila improved liver fibrosis and hyperammonemia with changing bacterial composition in the small intestine. This study proposed a new concept "small intestine-liver axis" in the pathophysiology of LC and oral A. muciniphila administration is a promising microbial intervention.

TNF compromises intestinal bile-acid tolerance dictating colitis progression and limited infliximab response

The intestine constantly encounters and adapts to the external environment shaped by diverse dietary nutrients. However, whether and how gut adaptability to dietary challenges is compromised in ulcerative colitis is incompletely understood. Here, we show that a transient high-fat diet exacerbates colitis owing to inflammation-compromised bile acid tolerance. Mechanistically, excessive tumor necrosis factor (TNF) produced at the onset of colitis interferes with bile-acid detoxification through the receptor-interacting serine/threonine-protein kinase 1/extracellular signal-regulated kinase pathway in intestinal epithelial cells, leading to bile acid overload in the endoplasmic reticulum and consequent apoptosis. In line with the synergy of bile acids and TNF in promoting gut epithelial damage, high intestinal bile acids correlate with poor infliximab response, and bile acid clearance improves infliximab efficacy in experimental colitis. This study identifies bile acids as an "opportunistic pathogenic factor" in the gut that would represent a promising target and stratification criterion for ulcerative colitis prevention/therapy.

Gut pathobiome mediates behavioral and developmental disorders in biotoxin-exposed amphibians

Emerging evidence suggests a link between alterations in the gut microbiome and adverse health outcomes in the hosts exposed to environmental pollutants. Yet, the causal relationships and underlying mechanisms remain largely undefined. Here we show that exposure to biotoxins can affect gut pathobiome assembly in amphibians, which in turn triggers the toxicity of exogenous pollutants. We used Xenopus laevis as a model in this study. Tadpoles exposed to tropolone demonstrated notable developmental impairments and increased locomotor activity, with a reduction in total length by 4.37%-22.48% and an increase in swimming speed by 49.96%-84.83%. Fusobacterium and Cetobacterium are predominant taxa in the gut pathobiome of tropolone-exposed tadpoles. The tropolone-induced developmental and behavioral disorders in the host were mediated by assembly of the gut pathobiome, leading to transcriptome reprogramming. This study not only advances our understanding of the intricate interactions between environmental pollutants, the gut pathobiome, and host health but also emphasizes the potential of the gut pathobiome in mediating the toxicological effects of environmental contaminants.

A Comprehensive Review on the Isolation, Bioactivities, and Structure-Activity Relationship of Hawthorn Pectin and Its Derived Oligosaccharides

Hawthorn (Crataegus pinnatifida Bunge) has been highlighted as an excellent source of a variety of bioactive polymers, which has attracted increasing research interest. Pectin, as a kind of soluble dietary fiber in hawthorn, is mainly extracted by hot water extraction and ultrasonic or enzymatic hydrolysis and is then extensively used in food, pharmaceutical, and nutraceutical industries. Numerous studies have shown that hawthorn pectin and its derived oligosaccharides exhibit a wide range of biological activities, such as antioxidant activity, hypolipidemic and cholesterol-reducing effects, antimicrobial activity, and intestinal function modulatory activity. As discovered, the bioactivities of hawthorn pectin and its derived oligosaccharides were mainly contributed by structural features and chemical compositions and were highly associated with the extraction methods. Additionally, hawthorn pectin is a potential resource for the development of emulsifiers and gelling agents, food packaging films, novel foods, and traditional medicines. This review provides a comprehensive summary of current research for readers on the extraction techniques, functional characteristics, structure-activity relationship, and applications in order to provide ideas and references for the investigation and utilization of hawthorn pectin and its derived oligosaccharides. Further research and development efforts are imperative to fully explore and harness the potential of hawthorn pectin-derived oligosaccharides in the food and medicine fields.

Oral Yak Whey Protein Can Alleviate UV-Induced Skin Photoaging and Modulate Gut Microbiota Composition

Excessive UV exposure can lead to skin roughness, wrinkles, pigmentation, and reduced elasticity, with severe cases potentially causing skin cancer. Nowadays, various anti-photoaging strategies have been developed to maintain skin health. Among them, dietary supplements with anti-photoaging properties are gaining increasing attention. Yak whey protein (YWP) possesses multiple benefits, including anti-inflammatory, antioxidant, and immune-boosting properties, effectively protecting the skin. This study used a mixed UVA and UVB light source to irradiate a nude mouse model, exploring the advantages of YWP in anti-photoaging and regulating gut microbiota. The results indicated that YWP alleviated UV-induced skin damage, wrinkles, dryness, and reduced elasticity by inhibiting oxidative stress, inflammatory factors (IL-1α, IL-6, and TNF-α), and matrix metalloproteinases (MMP-1, MMP-3, and MMP-12), thereby increasing the levels of elastin, type I collagen, and type III collagen in the extracellular matrix (ECM). Additionally, YWP significantly improved the abundance of Firmicutes and Bacteroidota in the gut microbiota of mice, promoting the growth of beneficial bacteria such as Lachnospiraceae_NK4A136_group, Ruminococcus_torques_group, and Clostridia_UCG_014, mitigating the dysbiosis caused by photoaging. These findings underscore the potential of YWP in anti-photoaging and gut microbiota improvement, highlighting it as a promising functional food for enhancing skin and gut health.

USP7 promotes cardiometabolic disorders and mitochondrial homeostasis dysfunction in diabetic mice via stabilizing PGC1β

Diabetic cardiomyopathy (DCM) is a major complication of diabetes and is characterized by left ventricular dysfunction. Currently, there is a lack of effective treatments for DCM. Ubiquitin-specific protease 7 (USP7) plays a key role in various diseases. However, whether USP7 is involved in DCM has not been established. In this study, we demonstrated that USP7 was upregulated in diabetic mouse hearts and NMCMs co-treated with HG+PA or H9c2 cells treated with PA. Abnormalities in diabetic heart morphology and function were reversed by USP7 silencing through conditional gene knockout or chemical inhibition. Proteomic analysis coupled with biochemical validation confirmed that PCG1β was one of the direct protein substrates of USP7 and aggravated myocardial damage through coactivation of the PPARα signaling pathway. USP7 silencing restored the expression of fatty acid metabolism-related proteins and restored mitochondrial homeostasis by inhibiting mitochondrial fission and promoting fusion events. Similar effects were also observed in vitro. Our data demonstrated that USP7 promoted cardiometabolic metabolism disorders and mitochondrial homeostasis dysfunction via stabilizing PCG1β and suggested that silencing USP7 may be a therapeutic strategy for DCM.

Organoids in gastrointestinal diseases: from bench to clinic

The etiology of gastrointestinal (GI) diseases is intricate and multifactorial, encompassing complex interactions between genetic predisposition and gut microbiota. The cell fate change, immune function regulation, and microenvironment composition in diseased tissues are governed by microorganisms and mutated genes either independently or through synergistic interactions. A comprehensive understanding of GI disease etiology is imperative for developing precise prevention and treatment strategies. However, the existing models used for studying the microenvironment in GI diseases-whether cancer cell lines or mouse models-exhibit significant limitations, which leads to the prosperity of organoids models. This review first describes the development history of organoids models, followed by a detailed demonstration of organoids application from bench to clinic. As for bench utilization, we present a layer-by-layer elucidation of organoid simulation on host-microbial interactions, as well as the application in molecular mechanism analysis. As for clinical adhibition, we provide a generalized interpretation of organoid application in GI disease simulation from inflammatory disorders to malignancy diseases, as well as in GI disease treatment including drug screening, immunotherapy, and microbial-targeting and screening treatment. This review draws a comprehensive and systematical depiction of organoids models, providing a novel insight into the utilization of organoids models from bench to clinic.

Gut microbiota and serum metabolite signatures along the colorectal adenoma-carcinoma sequence: Implications for early detection and intervention

AIM

Our study focuses on the microbial and metabolomic profile changes during the adenoma stage, as adenomas can be considered potential precursors to colorectal cancer through the adenoma-carcinoma sequence. Identifying possible intervention targets at this stage may aid in preventing the progression of colorectal adenoma (CRA) to malignant lesions. Furthermore, we evaluate the efficacy of combined microbial and metabolite biomarkers in detecting CRA.

METHODS

Fecal metagenomic and serum metabolomic analyses were performed for the discovery of alterations of gut microbiome and metabolites in CRA patients (n = 26), Colorectal cancer (CRC) patients (n = 19), Familial Adenomatous Polyposis (FAP) patients (n = 10), and healthy controls (n = 20). Finally, analyzing the associations between gut microbes and metabolites was performed by a Receiver Operating Characteristic (ROC) curve.

RESULTS

Our analysis present that CRA patients differ significantly in gut microflora and serum metabolites compared with healthy controls, especially for Lachnospiraceae and Parasutterella. Its main metabolite, butyric acid, concentrations were raised in CRA patients compared with the healthy controls, indicating its role as a promoter of colorectal tumorigenesis. α-Linolenic acid and lysophosphatidylcholine represented the other healthy metabolite for CRA. Combining five microbial and five metabolite biomarkers, we differentiated CRA from CRC with an Area Under the Curve (AUC) of 0.85 out of this performance vastly superior to the specificity recorded by traditional markers CEA and CA199 in such differentiation of these conditions.

CONCLUSIONS

The study underlines significant microbial and metabolic alterations in CRA with a novel insight into screening and early intervention of its tumorigenesis.

Study on the Impact of Dietary Patterns on Cardiovascular Metabolic Comorbidities among Adults

Background

The prevalence of cardiovascular metabolic comorbidities (CMM) among adults is relatively high, imposing a heavy burden on individuals, families, and society. Dietary patterns play a significant role in the occurrence and development of CMM. This study aimed to identify the combined types of CMM in adult populations and investigate the impact of dietary patterns on CMM.

Methods

Participants in this study were from the sixth wave of the China Health and Nutrition Survey (CHNS). Dietary intake was assessed using a three-day 24-hour dietary recall method among 4,963 participants. Latent profile analysis was used to determine dietary pattern types. Two-step cluster analysis was performed to identify the combined types of CMM based on the participants' conditions of hyperuricemia, dyslipidemia, diabetes, renal dysfunction, hypertension, and stroke. Logistic regression analysis with robust standard errors was used to determine the impact of dietary patterns on CMM.

Results

Participants were clustered into three dietary patterns (Pattern 1 to 3) and five CMM types (Class I to V). Class I combined six diseases, with a low proportion of diabetes. Class II also combined six diseases but with a high proportion of diabetes. Class III combined four diseases, with a high proportion of hypertension. Class IV combined three diseases, with the highest proportions of hyperuricemia, diabetes, and renal dysfunction. Class V combined two diseases, with high proportions of dyslipidemia and renal dysfunction. Patients with Class III CMM had a significantly higher average age than the other four classes (P ≤ 0.05). Compared to those with isolated dyslipidemia, individuals with a low-grain, high-fruit, milk, and egg (LCHFM) dietary pattern had a higher risk of developing dyslipidemia combined with renal dysfunction (Class V CMM) with an odds ratio of 2.001 (95% CI 1.011-3.960, P≤ 0.05).

Conclusion

For individuals with isolated dyslipidemia, avoiding a low-grain, high-fruit, milk, and egg (LCHFM) dietary pattern may help reduce the risk of developing dyslipidemia combined with renal dysfunction (Class V CMM).

Neuroimmunophysiology of the gastrointestinal tract

Gut physiology is the epicenter of a web of internal communication systems (i.e., neural, immune, hormonal) mediated by cell-cell contacts, soluble factors, and external influences, such as the microbiome, diet, and the physical environment. Together these provide the signals that shape enteric homeostasis and, when they go awry, lead to disease. Faced with the seemingly paradoxical tasks of nutrient uptake (digestion) and retarding pathogen invasion (host defense), the gut integrates interactions between a variety of cells and signaling molecules to keep the host nourished and protected from pathogens. When the system fails, the outcome can be acute or chronic disease, often labeled as "idiopathic" in nature (e.g., irritable bowel syndrome, inflammatory bowel disease). Here we underscore the importance of a holistic approach to gut physiology, placing an emphasis on intercellular connectedness, using enteric neuroimmunophysiology as the paradigm. The goal of this opinion piece is to acknowledge the pace of change brought to our field via single-cell and -omic methodologies and other techniques such as cell lineage tracing, transgenic animal models, methods for culturing patient tissue, and advanced imaging. We identify gaps in the field and hope to inspire and challenge colleagues to take up the mantle and advance awareness of the subtleties, intricacies, and nuances of intestinal physiology in health and disease by defining communication pathways between gut resident cells, those recruited from the circulation, and "external" influences such as the central nervous system and the gut microbiota.

The microbiota drives diurnal rhythms in tryptophan metabolism in the stressed gut

Chronic stress disrupts microbiota-gut-brain axis function and is associated with altered tryptophan metabolism, impaired gut barrier function, and disrupted diurnal rhythms. However, little is known about the effects of acute stress on the gut and how it is influenced by diurnal physiology. Here, we used germ-free and antibiotic-depleted mice to understand how microbiota-dependent oscillations in tryptophan metabolism would alter gut barrier function at baseline and in response to an acute stressor. Cecal metabolomics identified tryptophan metabolism as most responsive to a 15-min acute stressor, while shotgun metagenomics revealed that most bacterial species exhibiting rhythmicity metabolize tryptophan. Our findings highlight that the gastrointestinal response to acute stress is dependent on the time of day and the microbiome, with a signature of stress-induced functional alterations in the ileum and altered tryptophan metabolism in the colon.

The microbiota and T cells non-genetically modulate inherited phenotypes transgenerationally

The host-microbiota relationship has evolved to shape mammalian physiology, including immunity, metabolism, and development. Germ-free models are widely used to study microbial effects on host processes such as immunity. Here, we find that both germ-free and T cell-deficient mice exhibit a robust sebum secretion defect persisting across multiple generations despite microbial colonization and T cell repletion. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that non-genetic information in the gametes is required for microbial-dependent phenotypic transmission. Accordingly, gene expression in early embryos derived from gametes from germ-free or T cell-deficient mice is strikingly and similarly altered. Our findings demonstrate that microbial- and immune-dependent regulation of non-genetic information in the gametes can transmit inherited phenotypes transgenerationally in mice. This mechanism could rapidly generate phenotypic diversity to enhance host adaptation to environmental perturbations.

Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.

Moderate intensity exercise may protect cardiac function by influencing spleen microbiome composition

The beneficial effects of physical exercise on human cardiorespiratory fitness might be through reduced systemic inflammation, but the mechanism remains a controversy. Recent studies have highlighted the importance of spleen microbiomes in immune regulation. Hence, we conducted a study using a high-fat diet and exercise mouse model to investigate the relationships among different exercise intensities, spleen microbiome composition, and cardiac function. The mice spleen contained a diverse array of microbiota. Different intensities of exercise resulted in varying compositions of the spleen microbiome, Treg cell levels, and mouse heart function. Additionally, the abundance of Lactobacillus johnsonii in the mouse spleen exhibited a positive correlation with Treg cell levels, suggesting that Lactobacillus johnsonii may contribute to the production of Treg cells, potentially explaining the protective role of moderate-intensity exercise on cardiac function. In conclusion, our findings provide evidence that moderate-intensity exercise may promote cardiac function protection by influencing the spleen microbiome composition.

Effects of Habitual Dietary Change on the Gut Microbiota and Health of Silkworms

Diet plays a crucial role in shaping the gut microbiota and overall health of animals. Traditionally, silkworms are fed fresh mulberry leaves, and artificial diets do not support good health. The aim of this study was to explore the relationship between the dietary transition from artificial diets to mulberry leaves and the effects on the gut microbiota and physiological changes in silkworms as a model organism. With the transition from artificial diets to mulberry leaves, the diversity of the silkworm gut microbiota increased, and the proportion of Enterococcus and Weissella, the dominant gut bacterial species in silkworms reared on artificial diets, decreased, whereas the abundance of Achromobacter and Rhodococcus increased. Dietary transition at different times, including the third or fifth instar larval stages, resulted in significant differences in the growth and development, immune resistance, and silk production capacity of silkworms. These changes might have been associated with the rapid adaptation of the intestinal microbiota of silkworms to dietary transition. This study preliminarily established a dietary transition-gut microbial model in silkworms based on the conversion from artificial diets to mulberry leaves, thus providing an important reference for future studies on the mechanisms through which habitual dietary changes affect host physiology through the gut microbiome.

Obesity induced disruption on diurnal rhythm of insulin sensitivity via gut microbiome-bile acid metabolism

The disruption of the diurnal rhythm has been recognized as a significant contributing factor to metabolic dysregulation. The important role of gut microbiota and bile acid metabolism has attracted extensive attention. However, the function of the gut microbiota-bile acid axis in regulating the diurnal rhythms of metabolic homeostasis remains largely unknown. Herein, we aimed to investigate the interplay between rhythmicity of host metabolism and gut microbiota-bile acid axis, as well as to assess the impact of obesity on them. We found that high fat diet feeding and Leptin gene deficiency (ob/ob) significantly disturbed the rhythmic patterns of insulin sensitivity and serum total cholesterol levels. The bile acid profiling unveiled a conspicuous diurnal rhythm oscillation of ursodeoxycholic acid (UDCA) in lean mice, concomitant with fluctuations in insulin sensitivity, whereas it was absent in obese mice. The aforementioned diurnal rhythm oscillations were largely desynchronized by gut microbiota depletion, suggesting the indispensable role of gut microbiota in diurnal regulation of insulin sensitivity and bile acid metabolism. Consistently, 16S rRNA sequencing revealed that UDCA-associated bacteria exhibited diurnal rhythm oscillations that paralleled the fluctuation in insulin sensitivity. Collectively, the current study provides compelling evidence regarding the association between diurnal rhythm of insulin sensitivity and gut microbiota-bile acid axis. Moreover, we have elucidated the deleterious effects of obesity on gut microbiome-bile acid metabolism in both the genetic obesity model and the diet-induced obesity model.

Exploring a novel therapeutic strategy: the interplay between gut microbiota and high-fat diet in the pathogenesis of metabolic disorders

In the past two decades, the rapid increase in the incidence of metabolic diseases, including obesity, diabetes, dyslipidemia, non-alcoholic fatty liver disease, hypertension, and hyperuricemia, has been attributed to high-fat diets (HFD) and decreased physical activity levels. Although the phenotypes and pathologies of these metabolic diseases vary, patients with these diseases exhibit disease-specific alterations in the composition and function of their gut microbiota. Studies in germ-free mice have shown that both HFD and gut microbiota can promote the development of metabolic diseases, and HFD can disrupt the balance of gut microbiota. Therefore, investigating the interaction between gut microbiota and HFD in the pathogenesis of metabolic diseases is crucial for identifying novel therapeutic strategies for these diseases. This review takes HFD as the starting point, providing a detailed analysis of the pivotal role of HFD in the development of metabolic disorders. It comprehensively elucidates the impact of HFD on the balance of intestinal microbiota, analyzes the mechanisms underlying gut microbiota dysbiosis leading to metabolic disruptions, and explores the associated genetic factors. Finally, the potential of targeting the gut microbiota as a means to address metabolic disturbances induced by HFD is discussed. In summary, this review offers theoretical support and proposes new research avenues for investigating the role of nutrition-related factors in the pathogenesis of metabolic disorders in the organism.

New Awareness of the Interplay Between the Gut Microbiota and Circadian Rhythms

Circadian rhythms influence various aspects of the biology and physiology of the host, such as food intake and sleep/wake cycles. In recent years, an increasing amount of genetic and epidemiological data has shown that the light/dark cycle is the main cue that regulates circadian rhythms. Other factors, including sleep/wake cycles and food intake, have necessary effects on the composition and rhythms of the gut microbiota. Interestingly, the gut microbiota can affect the circadian rhythm of hosts in turn through contact-dependent and contact-independent mechanisms. Furthermore, the gut microbiota has been shown to regulate the sleep/wake cycles through gut-brain-microbiota interaction. In addition to diabetes, the gut microbiota can also intervene in the progression of neuro- degenerative diseases through the gut-brain-microbiota interaction, and also in other diseases such as hypertension and rheumatoid arthritis, where it is thought to have a spare therapeutic potential. Even though fecal microbiota transplantation has good potential for treating many diseases, the risk of spreading intestinal pathogens should not be ignored.

Gut microbiota-mediated IL-22 alleviates metabolic inflammation

Low-grade chronic inflammation, also known as metabolic inflammation, promotes the development of metabolic diseases. Increasing evidence suggests that changes in gut microbes and metabolites disrupt the integrity of the gut barrier and exert significant effects on the metabolism of various tissues, including the liver and adipose tissue, thereby contributing to metabolic inflammation. We observed that IL-22 is a key signaling molecule that serves as a bridge between intestinal microbes and the host, effectively alleviating metabolic inflammation by modulating the host immunomodulatory network. Here, we focused on elucidating the underlying mechanisms by which the gut microbiota and their metabolites reduce inflammation via IL-22, highlighting the favorable impact of IL-22 on metabolic inflammation. Furthermore, we discuss the potential of IL-22 as a therapeutic target for the management of metabolic inflammation and related diseases.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

High-fat diet promotes colitis-associated tumorigenesis by altering gut microbial butyrate metabolism

Background: Dietary fat intake is associated with an increased risk of colitis associated cancer (CAC). A high-fat diet (HFD) leads to systemic low-grade inflammation. The colon is believed to be the first organ suffering from inflammation caused by the infiltration of pro-inflammatory macrophages, and promotes CAC progression. We explored the role of HFD in driving CAC by altering gut microbial butyrate metabolism. Methods: Changes in the gut microbiota caused by HFD were investigated via HFD treatment or fecal microbiota transplantation (FMT). The underlying mechanisms were further explored by analyzing the role of gut microbiota, microbial butyrate metabolism, and NLRP3 inflammasome in colon tissues in a CAC mouse model. Results: HFD accelerated CAC progression in mice, and it could be reversed by broad-spectrum antibiotics (ABX). 16S-rRNA sequencing revealed that HFD inhibited the abundance of butyrate-producing bacteria in the gut. The level of short-chain fatty acids (SCFAs), especially butyrate, in the gut of mice treated with HFD was significantly reduced. In addition, treatment with exogenous butyrate reversed the M1 polarization of proinflammatory macrophages, aggravation of intestinal inflammation, and accelerated tumor growth induced by HFD; the NLRP3/Caspase-1 pathway activated by HFD in the colon was also significantly inhibited. In vitro, macrophages were treated with lipopolysaccharide combined with butyrate to detect the M1 polarization level and NLRP3/Caspase-1 pathway expression, and the results were consistent with those of the in vivo experiments. Conclusion: HFD drives colitis-associated tumorigenesis by inducing gut microbial dysbiosis and inhibiting butyrate metabolism to skew macrophage polarization. Exogenous butyrate is a feasible new treatment strategy for CAC, and has good prospect for clinical application.

Reg3γ: current understanding and future therapeutic opportunities in metabolic disease

Regenerating family member gamma, Reg3γ (the mouse homolog of human REG3A), belonging to the antimicrobial peptides (AMPs), functions as a part of the host immune system to maintain spatial segregation between the gut bacteria and the host in the intestine via bactericidal activity. There is emerging evidence that gut manipulations such as bariatric surgery, dietary supplementation or drug treatment to produce metabolic benefits alter the gut microbiome. In addition to changes in a wide range of gut hormones, these gut manipulations also induce the expression of Reg3γ in the intestine. Studies over the past decades have revealed that Reg3γ not only plays a role in the gut lumen but can also contribute to host physiology through interaction with the gut microbiota. Herein, we discuss the current knowledge regarding the biology of Reg3γ, its role in various metabolic functions, and new opportunities for therapeutic strategies to treat metabolic disorders.

Maternal High-Fat Diet Results in Long-Term Sex-Specific Alterations to Metabolic and Gut Microbial Diurnal Oscillations in Adult Offspring

SCOPE

Circadian rhythms profoundly impact metabolism and the gut microbiota. A maternal high-fat diet (HFD) exerts effects on the metabolic syndrome of adult offspring in a sex-specific manner, the underlying mechanisms, however, remain unclear.

METHODS AND RESULTS

Female mice are fed an HFD and raise their offspring on a standard chow diet until 24 weeks. The glucose tolerance, insulin sensitivity, and diurnal rhythms of serum metabolic profiles are assessed in male and female adult offspring. Simultaneously, 16S rRNA is applied to characterize gut microbiota diurnal rhythms. The study finds that maternal HFD tends to deteriorate glucose tolerance and impairs insulin sensitivity in male offspring, but not female offspring, which can be associated with the circadian alterations of serum metabolic profiles in male offspring. As expected, maternal HFD sex-specifically alters diurnal rhythms of the gut microbiota, which exhibits putative associations with metabolic profiles in males.

CONCLUSIONS

The present study identifies the critical role of gut microbiota diurnal rhythms in triggering sex-biased metabolic diurnal rhythms in response to maternal HFD, at least in part. As early life may be a critical window for preventing metabolic diseases, these findings provide the basis for developing chronobiology applications targeting the gut microbiota to combat early metabolic alterations, especially in males.

Intestinal α-Defensins Play a Minor Role in Modulating the Small Intestinal Microbiota Composition as Compared to Diet

The intestinal microbiota is at the interface between the host and its environment and thus under constant exposure to host-derived and external modulators. While diet is considered to be an important external factor modulating microbiota composition, intestinal defensins, one of the major classes of antimicrobial peptides, have been described as key host effectors that shape the gut microbial community. However, since dietary compounds can affect defensin expression, thereby indirectly modulating the intestinal microbiota, their individual contribution to shaping gut microbiota composition remains to be defined. To disentangle the complex interaction among diet, defensins, and small-intestinal microbiota, we fed wild-type (WT) mice and mice lacking functionally active α-defensins (Mmp7-/- mice) either a control diet or a Western-style diet (WSD) that is rich in saturated fat and simple carbohydrates but low in dietary fiber. 16S rDNA sequencing and robust statistical analyses identified that bacterial composition was strongly affected by diet while defensins had only a minor impact. These findings were independent of sample location, with consistent results between the lumen and mucosa of the jejunum and ileum, in both mouse genotypes. However, distinct microbial taxa were also modulated by α-defensins, which was supported by differential antimicrobial activity of ileal protein extracts. As the combination of WSD and defensin deficiency exacerbated glucose metabolism, we conclude that defensins only have a fine-tuning role in shaping the small-intestinal bacterial composition and might instead be important in protecting the host against the development of diet-induced metabolic dysfunction. IMPORTANCE Alterations in the gut microbial community composition are associated with many diseases, and therefore identifying factors that shape the microbial community under homeostatic and diseased conditions may contribute to the development of strategies to correct a dysbiotic microbiota. Here, we demonstrate that a Western-style diet, as an extrinsic parameter, had a stronger impact on shaping the small intestinal bacterial composition than intestinal defensins, as an intrinsic parameter. While defensins have been previously shown to modulate bacterial composition in young mice, our study supplements these findings by showing that defensins may be less important in adult mice that harbor a mature microbial community. Nevertheless, we observed that defensins did affect the abundance of distinct bacterial taxa in adult mice and protected the host from aggravated diet-induced glucose impairments. Consequently, our study uncovers a new angle on the role of intestinal defensins in the development of metabolic diseases in adult mice.

The Chinese herbal medicine Fufang Zhenzhu Tiaozhi ameliorates diabetic cardiomyopathy by regulating cardiac abnormal lipid metabolism and mitochondrial dynamics in diabetic mice

Diabetic cardiomyopathy (DCM) is an important complication leading to the death of patients with diabetes, but there is no effective strategy for clinical treatments. Fufang Zhenzhu Tiaozhi (FTZ) is a patent medicine that is a traditional Chinese medicine compound preparation with comprehensive effects for the prevention and treatment of glycolipid metabolic diseases under the guidance of "modulating liver, starting pivot and cleaning turbidity". FTZ was proposed by Professor Guo Jiao and is used for the clinical treatment of hyperlipidemia. This study was designed to explore the regulatory mechanisms of FTZ on heart lipid metabolism dysfunction and mitochondrial dynamics disorder in mice with DCM, and it provides a theoretical basis for the myocardial protective effect of FTZ in diabetes. In this study, we demonstrated that FTZ protected heart function in DCM mice and downregulated the overexpression of free fatty acids (FFAs) uptake-related proteins cluster of differentiation 36 (CD36), fatty acid binding protein 3 (FABP3) and carnitine palmitoyl transferase 1 (CPT1). Moreover, FTZ treatment showed a regulatory effect on mitochondrial dynamics by inhibiting mitochondrial fission and promoting mitochondrial fusion. We also identified in vitro that FTZ could restore lipid metabolism-related proteins, mitochondrial dynamics-related proteins and mitochondrial energy metabolism in PA-treated cardiomyocytes. Our study indicated that FTZ improves the cardiac function of diabetic mice by attenuating the increase in fasting blood glucose levels, inhibiting the decrease in body weight, alleviating disordered lipid metabolism, and restoring mitochondrial dynamics and myocardial apoptosis in diabetic mouse hearts.

Microbial circadian clocks: host-microbe interplay in diel cycles

BACKGROUND

Circadian rhythms, observed across all domains of life, enable organisms to anticipate and prepare for diel changes in environmental conditions. In bacteria, a circadian clock mechanism has only been characterized in cyanobacteria to date. These clocks regulate cyclical patterns of gene expression and metabolism which contribute to the success of cyanobacteria in their natural environments. The potential impact of self-generated circadian rhythms in other bacterial and microbial populations has motivated extensive research to identify novel circadian clocks.

MAIN TEXT

Daily oscillations in microbial community composition and function have been observed in ocean ecosystems and in symbioses. These oscillations are influenced by abiotic factors such as light and the availability of nutrients. In the ocean ecosystems and in some marine symbioses, oscillations are largely controlled by light-dark cycles. In gut systems, the influx of nutrients after host feeding drastically alters the composition and function of the gut microbiota. Conversely, the gut microbiota can influence the host circadian rhythm by a variety of mechanisms including through interacting with the host immune system. The intricate and complex relationship between the microbiota and their host makes it challenging to disentangle host behaviors from bacterial circadian rhythms and clock mechanisms that might govern the daily oscillations observed in these microbial populations.

CONCLUSIONS

While the ability to anticipate the cyclical behaviors of their host would likely be enhanced by a self-sustained circadian rhythm, more evidence and further studies are needed to confirm whether host-associated heterotrophic bacteria possess such systems. In addition, the mechanisms by which heterotrophic bacteria might respond to diel cycles in environmental conditions has yet to be uncovered.

The microbiota and immune system non-genetically affect offspring phenotypes transgenerationally

The host-microbiota relationship has evolved to shape mammalian processes, including immunity, metabolism, and development 1-3 . Host phenotypes change in direct response to microbial exposures by the individual. Here we show that the microbiota induces phenotypic change not only in the individual but also in their succeeding generations of progeny. We found that germ-free mice exhibit a robust sebum secretion defect and transcriptional changes in various organs, persisting across multiple generations despite microbial colonization and breeding with conventional mice. Host-microbe interactions could be involved in this process, since T cell-deficient mice, which display defective sebum secretion 4 , also transgenerationally transmit their phenotype to progeny. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that epigenetic information in the gametes is required for phenotypic transmission. Accordingly, small non-coding RNAs that can regulate embryonic gene expression 5 were strikingly and similarly altered in gametes of germ-free and T cell-deficient mice. Thus, we have uncovered a novel mechanism whereby the microbiota and immune system induce phenotypic changes in successive generations of offspring. This epigenetic form of inheritance could be advantageous for host adaptation to environmental perturbation, where phenotypic diversity can be introduced more rapidly than by genetic mutation.

Fecal Microbiota Composition as a Metagenomic Biomarker of Dietary Intake

Gut microbiota encompasses the set of microorganisms that colonize the gastrointestinal tract with mutual relationships that are key for host homeostasis. Increasing evidence supports cross intercommunication between the intestinal microbiome and the eubiosis-dysbiosis binomial, indicating a networking role of gut bacteria as potential metabolic health surrogate markers. The abundance and diversity of the fecal microbial community are already recognized to be associated with several disorders, such as obesity, cardiometabolic events, gastrointestinal alterations, and mental diseases, which suggests that intestinal microbes may be a valuable tool as causal or as consequence biomarkers. In this context, the fecal microbiota could also be used as an adequate and informative proxy of the nutritional composition of the food intake and about the adherence to dietary patterns, such as the Mediterranean or Western diets, by displaying specific fecal microbiome signatures. The aim of this review was to discuss the potential use of gut microbial composition as a putative biomarker of food intake and to screen the sensitivity value of fecal microbiota in the evaluation of dietary interventions as a reliable and precise alternative to subjective questionnaires.