The Short Chain Fatty Acid Butyrate Imprints an Antimicrobial Program in Macrophages

Gut microbiota in hepatocellular carcinoma immunotherapy: immune microenvironment remodeling and gut microbiota modification

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality, with limited treatment options at advanced stages. The gut microbiota, a diverse community of microorganisms residing in the gastrointestinal tract, plays a pivotal role in regulating immune responses through the gut-liver axis. Emerging evidence underscores its impact on HCC progression and the efficacy of immunotherapy. This review explores the intricate interactions between gut microbiota and the immune system in HCC, with a focus on key immune cells and pathways involved in tumor immunity. Additionally, it highlights strategies for modulating the gut microbiota - such as fecal microbiota transplantation, dietary interventions, and probiotics - as potential approaches to enhancing immunotherapy outcomes. A deeper understanding of these mechanisms could pave the way for novel therapeutic strategies aimed at improving patient prognosis.

Alleviative effect of probiotics and prebiotics on dry eye in type 2 diabetic mice through the gut-eye axis

Diabetes Mellitus (DM) is a metabolic disease that manifests as a state of "chronic low-grade inflammation". Patients with DM have a disorder of intestinal flora. There is a discernible correlation between this disorder of intestinal flora and the onset and progression of eye diseases, which offers novel insights into treating eye diseases through the modulation of intestinal flora. Here, we demonstrated that a high-fat diet and streptozotocin injection-induced intestinal microbiota dysbiosis can lead to dry eye-like manifestations in T2DM mice. Probiotic and prebiotic treatments not only alleviated intestinal inflammation and barrier disruption, but also mitigated damage to the lacrimal barrier and suppressed immune cell infiltration and inflammatory responses. Additional mechanism investigation found that probiotics and prebiotics inhibited the TLR4/NF-κB signaling pathway and its downstream pro-inflammatory products both in the lacrimal gland and colon. 16S RNA sequencing identified a reduction in the bacterial genera Akkermansia and Lactobacillus in the fecal samples of DM mice. By contrast, treatment with probiotics and prebiotics led to a reshaping of the intestinal microbial community and a reduction in bile acid metabolites, such as taurocholic acid and deoxycholic acid. Our current study demonstrates that probiotic and prebiotic treatments can ameliorate dry eye-like symptoms and associated pathological changes in T2DM mice. Moreover, we proved that a high-fat diet and STZ-induced microbiota dysbiosis were involved in diabetic dry eye through the gut-eye axis.

Mechanism of liver x receptor alpha in intestine, liver and adipose tissues in metabolic associated fatty liver disease

Metabolism associated fatty liver disease (MAFLD) has emerged as a growing global health challenge with limited effective treatments. Research on nuclear receptors offers promising new therapeutic avenues for MAFLD. The liver X receptor (LXR) has gained attention for its roles in tumors and metabolic and inflammatory diseases; However, its effects on MAFLD treatment remain a subject of debate. This review explores the therapeutic role of LXRα in MAFLD, focusing on its functions in the intestine, hepatic and adipose tissue, and summarizes recent advancements in LXRα ligands over the past five years. In the intestine, LXRα activation enhances the efflux of non-biliary cholesterol and reduces inflammation in the gut-liver axis by regulating intestinal high-density lipoprotein synthesis and its interaction with lipopolysaccharide. In the liver, LXRα activation facilitates cholesterol transport, influences hepatic lipid synthesis, and exerts anti-inflammatory effects. In adipose tissue, LXRα helps delay MAFLD progression by managing lipid autophagy and insulin resistance. Ligands that modulate LXRα transcriptional activity show considerable promise for MAFLD treatment.

Inflammation and cancer: molecular mechanisms and clinical consequences

Inflammation, a hallmark of cancer, has been associated with tumor progression, transition into malignant phenotype and efficacy of anticancer treatments in cancer. It affects all stages of cancer, from the initiation of carcinogenesis to metastasis. Chronic inflammation induces immunosup-pression, providing an environment conducive to carcinogenesis, whereas acute inflammation induces an antitumor immune response, leading to tumor suppression. Solid tumors have an inflammatory tumor microenvironment (TME) containing cancer cells, immune cells, stromal cells, and soluble molecules, which plays a key role in tumor progression and therapy response. Both cancer cells and stromal cells in the TME are highly plastic and constantly change their phenotypic and functional properties. Cancer-associated inflammation, the majority of which consists of innate immune cells, plays an important role in cancer cell plasticity, cancer progression and the development of anticancer drug resistance. Today, with the combined used of advanced technologies, such as single-cell RNA sequencing and spatial molecular imaging analysis, the pathways linking chronic inflammation to cancer have been largely elucidated. In this review article, we highlighted the molecular and cellular mechanisms involved in cancer-associated inflammation and its effects on cancer progression and treatment response. We also comprehensively review the mechanisms linking chronic inflammation to cancer in the setting of GI cancers.

Exploring effects of gut microbiota on tertiary lymphoid structure formation for tumor immunotherapy

Anti-tumor immunity, including innate and adaptive immunity is critical in inhibiting tumorigenesis and development of tumor. The adaptive immunity needs specific lymph organs such as tertiary lymphoid structures (TLSs), which are highly correlated with improved survival outcomes in many cancers. In recent years, with increasing attention on the TLS in tumor microenvironment, TLSs have emerged as a novel target for anti-tumor therapy. Excitingly, studies have shown the contribution of TLSs to the adaptive immune responses. However, it is unclear how TLSs to form and how to more effectively defense against tumor through TLS formation. Recent studies have shown that the inflammation plays a critical role in TLS formation. Interestingly, studies have also found that gut microbiota can regulate the occurrence and development of inflammation. Therefore, we here summarize the potential effects of gut microbiota- mediated inflammation or immunosuppression on the TLS formation in tumor environments. Meanwhile, this review also explores how to manipulate mature TLS formation through regulating gut microbiota/metabolites or gut microbiota associated signal pathways for anti-tumor immunity, which potentially lead to a next-generation cancer immunotherapy.

Gut Microbiota Alterations in Patients With Kawasaki Disease

The intestinal microbiota influences many host biological processes, including metabolism, intestinal barrier functions, and immune responses in the gut and distant organs. Alterations in its composition have been associated with the development of inflammatory disorders and cardiovascular diseases, including Kawasaki disease (KD). KD is an acute pediatric vasculitis of unknown etiology and the leading cause of acquired heart disease in children in the United States. The presence of gastrointestinal symptoms in the acute phase of KD has been associated with an increased risk of treatment resistance and the development of coronary artery aneurysms. Studies report alterations in fecal bacterial communities of patients with KD, characterized by the blooming of pathogenic bacteria and decreased relative abundance of short-chain fatty acid-producing bacteria. However, causality and functionality cannot be established from these observational patient cohorts of KD. This highlights the need for more advanced and rigorous studies to establish causality and functionality in both experimental models of KD vasculitis and patient cohorts. Here, we review the evidence linking an altered gut microbiota composition to the development of KD, assess the potential mechanisms involved in this process, and discuss the potential therapeutic value of these observations.

Microbiome-based therapeutics for ocular diseases

The relationship between the gut microbiome and ocular health has garnered increasing attention within the scientific community. Recent research has focused on the gut-eye axis, examining whether imbalances within the gut microbiome can influence the development, progression and severity of ocular diseases, including dry eye disease, uveitis, and glaucoma. Dysbiosis within the gut microbiome is linked to immune dysregulation, chronic inflammation, and epithelial barrier dysfunction, all of which contribute to ocular pathology. This review synthesises current evidence on these associations, exploring how gut microbiome alterations drive disease mechanisms. Furthermore, it examines the therapeutic potential of microbiome-targeted interventions, including antibiotics, prebiotics, probiotics, and faecal microbiota transplantation, all of which aim to restore microbial balance and modulate immune responses. As the prevalence of these conditions continues to rise, a deeper understanding of the gut-eye axis may facilitate the development of novel, targeted therapies to address unmet needs in the management of ocular diseases.

Environmentally relevant concentrations of DBDPE (decabromodiphenyl ethane) induce intestinal toxicity in silkworms (Bombyx mori L.)

Decabromodiphenyl ethane (DBDPE) is one of the most extensively used novel brominated flame retardants, and it has been frequently detected in the global environment. Although organisms encounter various pollutants through the intestine, the toxicity effects of DBDPE exposure on the intestine and the potential mechanisms remain unclear. Here, by morphological observation, histopathology, high-throughput sequencing, and transcriptomics methods, we evaluated the effects of environmental (0.011 and 0.11 μg/g dw) and extreme DBDPE concentrations (1.1 and 11 μg/g dw) on the intestine of silkworms. Morphological observations revealed that 11 μg/g dw DBDPE significantly inhibited the development of silkworms. After DBDPE exposure, the intestinal tissue structure was significantly damaged. Furthermore, DBDPE exposure had a notably impact on the composition of the intestinal microbiota. Further RNA-seq analysis demonstrated that the transcription profiles of silkworms were markedly altered following DBDPE exposure, which was associated with enriched oxidative stress and protein export processes, downregulated transmembrane transport processes, and a series of disordered metabolic processes. Finally, the significant Spearman's correlation emphasizes the role of intestinal microbiota in the metabolic/immune dysregulation processes of silkworms. Overall, our results are the first to assess the toxic effects of environmentally relevant DBDPE concentrations on the insect intestine.

Promotion of Healthy Aging Through the Nexus of Gut Microbiota and Dietary Phytochemicals

Aging is associated with the decline of tissue and cellular functions, which can promote the development of age-related diseases like cancer, cardiovascular disease, neurodegeneration, and disorders of the musculoskeletal and immune systems. Healthspan is the length of time an individual is in good health and free from chronic diseases and disabilities associated with aging. Two modifiable factors that can influence healthspan, promote healthy aging, and prevent the development of age-related diseases, are diet and microbiota in the gastrointestinal tract (gut microbiota). This review will discuss how dietary phytochemicals and gut microbiota can work in concert to promote a healthy gut and healthy aging. First, an overview is provided of how the gut microbiota influences healthy aging through its impact on gut barrier integrity, immune function, mitochondria function, and oxidative stress. Next, the mechanisms by which phytochemicals effect gut health, inflammation, and nurture a diverse and healthy microbial composition are discussed. Lastly, we discuss how the gut microbiota can directly influence health by producing bioactive metabolites from phytochemicals in food like urolithin A, equol, hesperetin, and sulforaphane. These and other phytochemical-derived microbial metabolites that may promote healthspan are discussed. Importantly, an individual's capacity to produce health-promoting microbial metabolites from cruciferous vegetables, berries, nuts, citrus, and soy products will be dependent on the specific bacteria present in the individual's gut.

Cardiac energy metabolic disorder and gut microbiota imbalance: a study on the therapeutic potential of Shenfu Injection in rats with heart failure

Objective

To investigate the relationship between heart failure (HF) and gut microbiota-mediated energy metabolism, and to explore the role of Shenfu Injection in this process.

Materials and methods

In this study, Adriamycin-induced chronic heart failure (CHF) rat model was used and randomly divided into the blank control group (Normal, n = 9), HF control group (Model, n = 12), Shenfu Injection treatment group (SFI, n = 9), and positive drug control group (TMZ, n = 9). The changes in gut microbiota structure were analyzed by 16S rRNA high-throughput sequencing, the content of short-chain fatty acids (SCFAs) was detected by targeted metabolomics technology, and cardiac function and energy metabolism-related indicators were evaluated.

Results

Myocardial energy metabolism in HF rats was disordered, characterized by reduced fatty acid oxidation, enhanced anaerobic glycolysis of glucose, mitochondrial damage, and decreased ATP content; The gut microbiota of HF rats was imbalanced, with a reduction in beneficial bacteria, an increase in conditional pathogenic bacteria, and impaired intestinal barrier function; Both Shenfu Injection and trimetazidine improved myocardial energy metabolism and cardiac function, but Shenfu Injection was more significant in regulating gut microbiota and improving intestinal health; The production of SCFAs from the gut microbiota of HF rats increased, which may be closely related to myocardial energy metabolism; SCFAs-producing bacteria Akkermansia and Blautia played a key role in the development of HF, and their abundance was positively correlated with SCFAs content.

Conclusion

Shenfu Injection in treating HF may improve myocardial energy metabolism and intestinal health by regulating gut microbiota, especially the abundance of SCFAs-producing bacteria Akkermansia and Blautia, thereby exerting therapeutic effects. This provides theoretical support for treatment strategies based on gut microbiota.

Innovative Therapeutic Strategies for Asthma: The Role of Gut Microbiome in Airway Immunity

There is a growing acknowledgment of the gut microbiome's impact on widespread immune responses, which holds considerable importance for comprehending and addressing asthma. Recent research has clarified the complex interactions between gut microbiota and airway immune systems, demonstrating that microbial diversity and composition can affect both the initiation and advancement of asthma. Gut microbial species and metabolites primarily short-chain fatty acids (SCFAs) may either worsen or reduce airway inflammation by regulating the balance of helper T cell 1 (Th1) / helper T cell 2 (Th2) and other immune mediators. This interaction presents innovative therapeutic possibilities, including modulation of gut microbiome during early life through breastfeeding and control of antibiotic use, particularly with prebiotics, which could selectively stimulate the growth of beneficial bacteria, promote immune maturation, reducing susceptibility to asthma and allergic airway inflammation. Besides, investigating the gut-lung axis reveals new opportunities for personalized medicine in asthma treatment, emphasizing the necessity for integrated strategies that take individual microbiome profiles into account. This paper examines the latest developments in comprehending the mechanisms by which gut microbiota affect airway inflammation and hypersensitivity, especially focusing on treatment strategies.

HDAC3: A Multifaceted Modulator in Immunotherapy Sensitization

Histone deacetylase 3 (HDAC3) has emerged as a critical epigenetic regulator in tumor progression and immune modulation, positioning it as a promising target for enhancing cancer immunotherapy. This work comprehensively explores HDAC3's multifaceted roles, focusing on its regulation of key immune-modulatory pathways such as cGAS-STING, ferroptosis, and the Nrf2/HO-1 axis. These pathways are central to tumor immune evasion, antigen presentation, and immune cell activation. Additionally, the distinct effects of HDAC3 on various immune cell types-including its role in enhancing T cell activation, restoring NK cell cytotoxicity, promoting dendritic cell maturation, and modulating macrophage polarization-are thoroughly examined. These findings underscore HDAC3's capacity to reshape the tumor immune microenvironment, converting immunologically "cold tumors" into "hot tumors" and thereby increasing their responsiveness to immunotherapy. The therapeutic potential of HDAC3 inhibitors is highlighted, both as standalone agents and in combination with immune checkpoint inhibitors, to overcome resistance and improve treatment efficacy. Innovative strategies, such as the development of selective HDAC3 inhibitors, advanced nano-delivery systems, and integration with photodynamic or photothermal therapies, are proposed to enhance treatment precision and minimize toxicity. By addressing challenges such as toxicity, patient heterogeneity, and resistance mechanisms, this study provides a forward-looking perspective on the clinical application of HDAC3 inhibitors. It highlights its significant potential in personalized cancer immunotherapy, paving the way for more effective treatments and improved outcomes for cancer patients.

Microbiota translocation following intestinal barrier disruption promotes Mincle-mediated training of myeloid progenitors in the bone marrow

Impairment of the intestinal barrier allows the systemic translocation of commensal bacteria, inducing a proinflammatory state in the host. Here, we investigated innate immune responses following increased gut permeability upon administration of dextran sulfate sodium (DSS) in mice. We found that Enterococcus faecalis translocated to the bone marrow following DSS treatment and induced trained immunity (TI) hallmarks in bone-marrow-derived mouse macrophages and human monocytes. DSS treatment or heat-killed E. faecalis reprogrammed bone marrow progenitors (BMPs), resulting in enhanced inflammatory responses in vitro and in vivo and protection against subsequent pathogen infections. The C-type lectin receptor Mincle (Clec4e) was essential for E. faecalis-induced TI in BMPs. Clec4e-/- mice showed impaired TI upon E. faecalis administration and reduced pathology following DSS treatment. Thus, Mincle sensing of E. faecalis induces TI that may have long-term effects on pathologies associated with increased gut permeability.

The role of short-chain fatty acid in metabolic syndrome and its complications: focusing on immunity and inflammation

Metabolic syndrome (Mets) is an important contributor to morbidity and mortality in cardiovascular, liver, neurological, and reproductive diseases. Short-chain fatty acid (SCFA), an organismal energy donor, has recently been demonstrated in an increasing number of studies to be an important molecule in ameliorating immuno-inflammation, an important causative factor of Mets, and to improve lipid distribution, blood glucose, and body weight levels in animal models of Mets. This study reviews recent research advances on SCFA in Mets from an immune-inflammatory perspective, including complications dominated by chronic inflammation, as well as the fact that these findings also contribute to the understanding of the specific mechanisms by which gut flora metabolites contribute to metabolic processes in humans. This review proposes an emerging role for SCFA in the inflammatory Mets, followed by the identification of major ambiguities to further understand the anti-inflammatory potential of this substance in Mets. In addition, this study proposes novel strategies to modulate SCFA for the treatment of Mets that may help to mitigate the prognosis of Mets and its complications.

Short-chain fatty acids and cancer

Short-chain fatty acids (SCFAs), derived from the diet and the microbiota, serve as crucial links between the diet, gut microbiota, metabolism, immunity, and cancer. They function as energy sources through β-oxidation and regulate macromolecular synthesis, G protein-coupled receptor (GPCR) and histone deacetylase (HDAC) activities, protein modifications, signaling pathways, and gene expression in cells within the tumor microenvironment, particularly in tumor and immune cells. The critical role of SCFAs in maintaining normal homeostasis and influencing tumor progression highlights the potential of targeting SCFA-mediated cellular processes for cancer prevention and treatment.

Bacteria-tumor symbiosis destructible novel nanocatalysis drug delivery systems for effective tumor therapy

Colorectal cancer (CRC) is a significant threat to human health. The dynamic equilibrium between probiotics and pathogenic bacteria within the gut microbiota is crucial in mitigating the risk of CRC. An overgrowth of harmful microorganisms in the gastrointestinal tract can result in an excessive accumulation of bacterial toxins and carcinogenic metabolites, thereby disrupting the delicate balance of the microbiota. This disruption may lead to alterations in microbial composition, impairment of mucosal barrier function, potential promotion of abnormal cell proliferation, and ultimately contribute to the progression of CRC. Recently, research has indicated that intestinal presence of Fusobacterium nucleatum (Fn) significantly influences the onset, progression, and metastasis of CRC. Consequently, disrupting the interaction between CRC cells and Fn presents a promising strategy against CRC. Nanomaterials have been extensively utilized in cancer therapy and bacterial infection control, demonstrating substantial potential in treating bacteria-associated tumors. This review begins by elucidating the mechanisms of gut microbiota and the occurrence and progression of CRC, with a particular emphasis on clarifying the intricate relationship between Fn and CRC. Subsequently, we highlight strategies that utilize nanomaterials to disrupt the association between Fn and CRC. Overall, this review offers valuable insight and guidance for leveraging nanomaterials in CRC therapy.

Inducible antibacterial responses in macrophages

Macrophages destroy bacteria and other microorganisms through phagocytosis-coupled antimicrobial responses, such as the generation of reactive oxygen species and the delivery of hydrolytic enzymes from lysosomes to the phagosome. However, many intracellular bacteria subvert these responses, escaping to other cellular compartments to survive and/or replicate. Such bacterial subversion strategies are countered by a range of additional direct antibacterial responses that are switched on by pattern-recognition receptors and/or host-derived cytokines and other factors, often through inducible gene expression and/or metabolic reprogramming. Our understanding of these inducible antibacterial defence strategies in macrophages is rapidly evolving. In this Review, we provide an overview of the broad repertoire of antibacterial responses that can be engaged in macrophages, including LC3-associated phagocytosis, metabolic reprogramming and antimicrobial metabolites, lipid droplets, guanylate-binding proteins, antimicrobial peptides, metal ion toxicity, nutrient depletion, autophagy and nitric oxide production. We also highlight key inducers, signalling pathways and transcription factors involved in driving these different antibacterial responses. Finally, we discuss how a detailed understanding of the molecular mechanisms of antibacterial responses in macrophages might be exploited for developing host-directed therapies to combat antibiotic-resistant bacterial infections.

The Interplay of Nutrition, the Gut Microbiota and Immunity and Its Contribution to Human Disease

Nutrition, the gut microbiota and immunity are all important factors in the maintenance of health. However, there is a growing realization of the complex interplay between these elements coalescing in a nutrition-gut microbiota-immunity axis. This regulatory axis is critical for health with disruption being implicated in a broad range of diseases, including autoimmune disorders, allergies and mental health disorders. This new perspective continues to underpin a growing number of innovative therapeutic strategies targeting different elements of this axis to treat relevant diseases. This review describes the inter-relationships between nutrition, the gut microbiota and immunity. It then details several human diseases where disruption of the nutrition-gut microbiota-immunity axis has been identified and presents examples of how the various elements may be targeted therapeutically as alternate treatment strategies for these diseases.

Lewy body diseases and the gut

Gastrointestinal (GI) involvement in Lewy body diseases (LBDs) has been observed since the initial descriptions of patients by James Parkinson. Recent experimental and human observational studies raise the possibility that pathogenic alpha-synuclein (⍺-syn) might develop in the GI tract and subsequently spread to susceptible brain regions. The cellular and mechanistic origins of ⍺-syn propagation in disease are under intense investigation. Experimental LBD models have implicated important contributions from the intrinsic gut microbiome, the intestinal immune system, and environmental toxicants, acting as triggers and modifiers to GI pathologies. Here, we review the primary clinical observations that link GI dysfunctions to LBDs. We first provide an overview of GI anatomy and the cellular repertoire relevant for disease, with a focus on luminal-sensing cells of the intestinal epithelium including enteroendocrine cells that express ⍺-syn and make direct contact with nerves. We describe interactions within the GI tract with resident microbes and exogenous toxicants, and how these may directly contribute to ⍺-syn pathology along with related metabolic and immunological responses. Finally, critical knowledge gaps in the field are highlighted, focusing on pivotal questions that remain some 200 years after the first descriptions of GI tract dysfunction in LBDs. We predict that a better understanding of how pathophysiologies in the gut influence disease risk and progression will accelerate discoveries that will lead to a deeper overall mechanistic understanding of disease and potential therapeutic strategies targeting the gut-brain axis to delay, arrest, or prevent disease progression.

Unveiling the silent defenders: mycobacterial stress sensors at the forefront to combat tuberculosis

The global escalation in tuberculosis (TB) cases accompanied by the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (M.tb) emphasizes the critical requirement for novel potent drugs. The M.tb demonstrates extraordinary adaptability, thriving in diverse conditions, and always finds itself in win-win situations regardless of whether the environment is favorable or unfavorable; no matter the magnitude of the challenge, it can endure and survive. This review aims to uncover the role of multiple stress sensors of M.tb that assist bacteria in remaining viable within the host for years against various physiological stresses offered by the host. M.tb is an exceptionally triumphant pathogen, primarily due to its adeptness in developing defense mechanisms against stressful situations. The recent advances emphasize the significance of M.tb stress sensors, including chaperones, proteases, transcription factors, riboswitches, inteins, etc., employed in responding to a spectrum of physiological stresses imposed by the host, encompassing surface stress, host immune responses, osmotic stress, oxidative and nitrosative stresses, cell envelope stress, environmental stress, reductive stress, and drug pressure. These sensors act as silent defenders orchestrating adaptive strategies, with limited comprehensive information in current literature, necessitating a focused review. The M.tb strategies utilizing these stress sensors to mitigate the impact of traumatic conditions demand attention to neutralize this pathogen effectively. Moreover, the intricacies of these stress sensors provide potential targets to design an effective TB drug using structure-based drug design against this formidable global health threat.

Microbiome interplays in the gut-liver axis: implications for liver cancer pathogenesis and therapeutic insights

Globally, primary liver cancer (PLC) ranks the most fatal malignancy. Most of the patients are in advanced stage of PLC at the very time they are diagnosed with it, accounting much for its poor prognosis. With the advancement of modern medical research and care system, the main etiology of PLC more and more switches from hepatitis viruses such as HAV, HBV, HCV, HEV to other causes like metabolism-associated steatohepatitis (MASH) and metabolic-associated fatty liver disease (MAFLD). As a result, it is of great necessity to find out new ways for treatment and early diagnosis to cope with this problem. Nowadays, as the mechanism of the Gut-Liver Axis in the formation of MAFLD, MASH and PLC has been gradually elucidated. The association between gut microbiome and the formation of PLC is of great significance to take an insight into. In this review, we present the concept of Gut-Liver Axis and its function in the mutual influence between gut microbiota and PLC from several aspects in which we will focus on the structure of gut barrier and the functional influences the gut microbiota have on the immune response and metabolic changes on human liver. Furthermore, we conclude the potential association of gut microbiota constitution with the PLC. Eventually, we hope this review can offer novel instructions for early diagnosis and treatment for liver cancer.

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.

Metabolic tug-of-war: Microbial metabolism shapes colonization resistance against enteric pathogens

A widely recognized benefit of gut microbiota is that it provides colonization resistance against enteric pathogens. The gut microbiota and their products can protect the host from invading microbes directly via microbe-pathogen interactions and indirectly by host-microbiota interactions, which regulate immune system function. In contrast, enteric pathogens have evolved mechanisms to utilize microbiota-derived metabolites to overcome colonization resistance and increase their pathogenic potential. This review will focus on recent studies of metabolism-mediated mechanisms of colonization resistance and virulence strategies enteric pathogens use to overcome them, along with how induction of inflammation by pathogenic bacteria changes the landscape of the gut and enables alternative metabolic pathways. We will focus on how intestinal pathogens counteract the protective effects of microbiota-derived metabolites to illustrate the growing appreciation of how metabolic factors may serve as crucial virulence determinants and overcome colonization resistance.

From Gut to Brain: The Impact of Short-Chain Fatty Acids on Brain Cancer

The primary source of short-chain fatty acids (SCFAs), now recognized as critical mediators of host health, particularly in the context of neurobiology and cancer development, is the gut microbiota's fermentation of dietary fibers. Recent research highlights the complex influence of SCFAs, such as acetate, propionate, and butyrate, on brain cancer progression. These SCFAs impact immune modulation and the tumor microenvironment, particularly in brain tumors like glioma. They play a critical role in regulating cellular processes, including apoptosis, cell differentiation, and inflammation. Moreover, studies have linked SCFAs to maintaining the integrity of the blood-brain barrier (BBB), suggesting a protective role in preventing tumor infiltration and enhancing anti-tumor immunity. As our understanding of the gut-brain axis deepens, it becomes increasingly important to investigate SCFAs' therapeutic potential in brain cancer management. Looking into how SCFAs affect brain tumor cells and the environment around them could lead to new ways to prevent and treat these diseases, which could lead to better outcomes for people who are dealing with these challenging cancers.

Isolation and Evaluation of Potential Use of Prebiotics-Utilizing Butyrate-Producing Bacteria in Nibea coibor

Butyrate-producing bacteria (BPB) benefit the health of aquatic animals. This current study aimed to isolate BPB from the intestines of Nibea coibor and assess their probiotic potential. The results showed that nine isolates were obtained in vitro from the gut of N. coibor, including six Clostridium butyricum, two Proteocatella sphenisci, and one Fusobacterium varium. The representative bacteria, C. butyricum CG-3 and P. sphenisci DG-1, which produce high butyrate levels, were further studied for short-chain fatty acid (SCFA) production and antibiotic susceptibility. The effects of BPB singly (CB: basal diet + CG-3 and PS: basal diet + DG-1, at 107 CFU/g) or in combination with galactooligosaccharides (GOS) (0.5%) and inulin (0.5%) (CBIG) or D-sorbitol (0.5%) (PSGS) on the growth and health status of N. coibor were investigated. Results showed an increase in growth parameters in the CB, CBIG, and PSGS groups, except for the PS group. Alterations in intestinal microbiota (including diversity, abundance, and function) were observed in four experimental groups (CB, CBIG, PS, and PSGS groups). SCFA contents increased in treated groups; butyrate production was positively related to bacterial abundance. Compared to control, levels of complement C3, complement C4, immunoglobulin M (IgM), transforming growth factor-β (TGF-β), interleukin (IL)-10, IL-1β, and lysozyme (LZM) increased, while malondialdehyde (MDA) decreased in treated groups. Contents of IL-6 (PS and PSGS groups), tumor necrosis factor-alpha (TNF-α) (CB, PS, and PSGS groups), total antioxidant capacity (T-AOC) (CB and PS groups), total superoxide dismutase (T-SOD) (PS group), catalase (CAT) (CB and PSGS groups), and activities of amylase (PS and PSGS groups), trypsin (CB group), and lipase (CBIG group) were increased. Our results suggested the potential use of C. butyricum CG-1 or P. sphenisci DG-1 singly or in combination with prebiotics improved growth and health conditions in N. coibor.

Friends to remember: innate immune memory regulation by the microbiota

Innate immune memory (IIM) is the process by which, upon a primary challenge, innate immune cells alter their epigenetic, transcriptional, and immunometabolic profiles, resulting in modified secondary responses. Unlike infections or other immune-system-related diseases, the role of IIM in nonpathogenic contexts is less understood. An increasing body of research has shown that normal microbiota members or their metabolic byproducts induce alternative memory phenotypes, suggesting that memory cells contribute to homeostasis in mucosal areas. In this review, we discuss the newest insights in the emerging field of IIM to the microbiota and the potential of manipulating these long-term responses to promote better mucosal health.

Therapeutic potential of short-chain fatty acids for acute lung injury: a systematic review and meta-analysis of preclinical animal studies

Background

Short-chain fatty acids (SCFAs), derived from the fermentation of dietary fiber by intestinal commensal bacteria, have demonstrated protective effects against acute lung injury (ALI) in animal models. However, the findings have shown variability across different studies. It is necessary to conduct a comprehensive evaluation of the efficacy of these treatments and their consistency.

Objective

This systematic review and meta-analysis aimed to explore the effects of SCFAs on ALI based on preclinical research evidence, in order to provide new treatment strategies for ALI.

Methods

We included studies that tested the effects of SCFAs on ALI in animal models. This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search for relevant studies was conducted in the PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure (CNKI) databases up to February 2024. The data were extracted in accordance with the established selection criteria, and the risk of bias was evaluated for each study.

Results

A total of 16 articles were finally included in the meta-analysis. The results indicated that the SCFAs significantly reduced lung wet-to-dry weight (SMD = -2.75, 95% CI = -3.46 to -2.03, p < 0.00001), lung injury scores (SMD = -5.07, 95% CI = -6.25 to -3.89, p < 0.00001), myeloperoxidase (SMD = -3.37, 95% CI = -4.05 to -2.70, p < 0.00001), tumor necrosis factor-alpha (SMD = -3.31, 95% CI = -4.45 to -2.16, p < 0.00001) and malondialdehyde (SMD = -3.91, 95% CI = -5.37 to -2.44, p < 0.00001) levels in animal models of ALI. The results of the subgroup analysis indicated that the efficacy of SCFAs varies significantly with dosage and duration of treatment.

Conclusion

SCFAs can reduce inflammation and oxidative stress in animal models of ALI. The clinical efficacy of SCFAs for ALI deserves further in-depth research.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=584008, CRD42024584008.

Exploring the mediating role of blood metabolites in the relationship between gut microbiota and gastric cancer risk: a Mendelian randomization study

Background

Prior studies have established correlations between gut microbiota (GM) dysbiosis, circulating metabolite alterations, and gastric cancer (GC) risk. However, the causal nature of these associations remains uncertain.

Methods

We utilized summary data from genome-wide association studies (GWAS) on GM (European, n=8,956), blood metabolites (European, n=120,241; East Asian, n=4,435), and GC (European, n=476,116; East Asian, n=167,122) to perform a bidirectional Mendelian randomization (MR) analysis, investigating the causal effects of GM and metabolites on GC risk. Additionally, we conducted mediation analysis (two-step MR) to identify potential metabolite mediators in the GM-GC relationship.

Results

We identified twelve negative and seven positive associations between specific GM taxa and GC risk. For blood metabolites, seven traits were found to be significantly associated with reduced GC risk in the European population, with these findings subsequently validated in the East Asian cohort. Three GM taxa showed potential causal associations with five metabolic traits: the Bacteroidia class and Bacteroidales order were positively correlated with five metabolites (all P < 0.013), while Bacteroides OTU97_27 exhibited a negative correlation with one metabolite (P = 0.007). Two-step MR analysis indicated that total lipids in intermediate-density lipoprotein (IDL), IDL particle concentration, phospholipids in medium low-density lipoprotein (LDL), phospholipids in small LDL, and free cholesterol in small LDL indirectly influenced the association between Bacteroidia class/Bacteroidales order and GC, with mediation proportions of 1.71% (P = 0.048), 1.69% (P = 0.048), 2.05% (P = 0.045), 1.85% (P = 0.048), and 1.99% (P = 0.045), respectively.

Conclusion

The present study provides suggestive evidence of a causal relationship between specific GM, blood metabolites, and GC risk, potentially offering new insights into GC etiology.

Succinate-producing microbiota drives tuft cell hyperplasia to protect against Clostridioides difficile

The role of microbes and their metabolites in modulating tuft cell (TC) dynamics in the large intestine and the relevance of this pathway to infections is unknown. Here, we uncover that microbiome-driven colonic TC hyperplasia protects against Clostridioides difficile infection. Using selective antibiotics, we demonstrate increased type 2 cytokines and TC hyperplasia in the colon but not in the ileum. We demonstrate the causal role of the microbiome in modulating this phenotype using fecal matter transplantation and administration of consortia of succinate-producing bacteria. Administration of succinate production-deficient microbes shows a reduced response in a Pou2f3-dependent manner despite similar intestinal colonization. Finally, antibiotic-treated mice prophylactically administered with succinate-producing bacteria show increased protection against C. difficile-induced morbidity and mortality. This effect is nullified in Pou2f3-/- mice, confirming that the protection occurs via the TC pathway. We propose that activation of TCs by the microbiota in the colon is a mechanism evolved by the host to counterbalance microbiome-derived cues that facilitate invasion by pathogens.

Gut feelings on short-chain fatty acids to regulate respiratory health

Respiratory infections and diseases pose significant challenges to society and healthcare systems, underscoring the need for preventative and therapeutic strategies. Recent research in rodent models indicates that short-chain fatty acids (SCFAs), metabolites produced by gut bacteria, may offer medicinal benefits for respiratory conditions. In this opinion, we summarize the current literature that highlights the potential of SCFAs to enhance immune balance in humans. SCFAs have demonstrated the potential to decrease the risk of primary and secondary respiratory infections, modulate allergic airway exacerbations, and improve overall epithelial pathogen defenses. Therefore, we suggest that systemic SCFA levels could be targeted to support gut and respiratory health in specific groups, such as patients in hospital, women and their offspring, children, older adults, and athletes/military personnel.

Optimising vaccine immunogenicity in ageing populations: key strategies

Vaccination has been shown to be the most effective means of preventing infectious diseases, although older people commonly have a suboptimal immune response to vaccines and thus impaired protection against subsequent adverse outcomes. This Review provides an overview of the existing mechanistic insights into compromised vaccine response for respiratory infectious diseases in older people, defined as aged 65 years and older, including immunosenescence, epigenetic regulation, trained immunity, and gut microbiota. We further summarise the latest proven or potential strategies to strengthen weakened immunogenicity. Insights from these analyses will be conducive to the development of the next generation of vaccines.

Empirical antibiotic therapy for sepsis: save the anaerobic microbiota

Antibiotics are fundamental in sepsis management; however, the optimal empirical treatment remains debated. Despite anaerobes rarely being the causative pathogen of sepsis, antibiotics targeting them are frequently used, which might lead to unintended consequences. Multiple studies have shown that depletion of commensal anaerobic gut microbes by anti-anaerobic antibiotics influences systemic immunity and is associated with increased mortality in patients with sepsis. However, this knowledge has not yet been translated into clinical practice. When considering empirical coverage of anaerobic pathogens in sepsis, most physicians advocate for a better-safe-than-sorry approach. In this Viewpoint, we argue that anti-anaerobic antibiotics could often result in being sorry rather than safe. We provide an overview of the limited necessity of anaerobic coverage and the potential detrimental effects of anaerobic depletion in sepsis. We aim to raise anaerobic awareness to reduce the unnecessary use of anti-anaerobic antibiotics in empirical sepsis treatment and improve patient outcomes.

The effect of exercise on depression and gut microbiota: Possible mechanisms

Exercise can effectively prevent and treat depression and anxiety, with gut microbiota playing a crucial role in this process. Studies have shown that exercise can influence the diversity and composition of gut microbiota, which in turn affects depression through immune, endocrine, and neural pathways in the gut-brain axis. The effectiveness of exercise varies based on its type, intensity, and duration, largely due to the different changes in gut microbiota. This article summarizes the possible mechanisms by which exercise affects gut microbiota and how gut microbiota influences depression. Additionally, we reviewed literature on the effects of exercise on depression at different intensities, types, and durations to provide a reference for future exercise-based therapies for depression.

Reduced gut microbiota diversity in ulcerative colitis patients with latent tuberculosis infection during vedolizumab therapy: insights on prophylactic anti-tuberculosis effects

BACKGROUND

The gut microbiota plays a pivotal role in ulcerative colitis (UC) development. This study explores the impact of latent tuberculosis infection (LTBI) on the gut microbiota in UC and assesses changes during vedolizumab treatment, investigating prophylactic anti-tuberculosis therapy.

RESULTS

This cohort study included adult patients with UC receiving vedolizumab treatment at Jinhua Hospital, Zhejiang University from April 2021 to December 2022. Patients were divided into LTBI (n = 24) and non-LTBI (n = 21) groups. Patients in the LTBI group were further subdivided into prophylactic (n = 13) and non-prophylactic (n = 11) groups. Clinical and fecal samples were collected pre- and post-vedolizumab treatment for the LTBI groups and pre-treatment for the non-LTBI group. The gut microbiota was analyzed using 16 S rRNA sequencing. Patients in the non-LTBI group exhibited higher diversity indices. Vedolizumab demonstrated efficacy in the LTBI group, with clinical response and remission rates of 83.3% and 75.0%, respectively. The gut microbiota diversity in the LTBI group increased post-vedolizumab treatment, and receiving prophylactic isoniazid showed no significant difference in vedolizumab treatment response compared to not receiving prophylactic isoniazid. Microbiota changes were similar between groups, with an increase in [Ruminococcus] expression after vedolizumab treatment.

CONCLUSIONS

This cohort study, conducted at a single center, highlights that LTBI can reduce gut microbiota diversity among adult patient with UC. The observed efficacy of vedolizumab treatment in the LTBI group indicates a potential association with microbiota changes. However, mono-isoniazid exhibited limited impact, underscoring the potential of vedolizumab as a promising candidate for prophylactic anti-tuberculosis treatment in the context of UC.

Butyrate attenuates intestinal inflammation in Crohn's disease by suppressing pyroptosis of intestinal epithelial cells via the cGSA-STING-NLRP3 axis

Butyrate can strengthen the intestinal epithelial barrier. However, the mechanisms by which butyrate affects intestinal epithelial cells (IECs) pyroptosis in Crohn's disease (CD) remain unclear. In this study, we collected colonic biopsy samples from CD patients and healthy controls to assess pyroptosis levels. Our findings indicated elevated expression of pyroptosis markers in CD patients, alongside distinct morphological evidence of pyroptosis in IECs. We further investigated the effects of tributyrin on pyroptosis and the cGAS-STING pathway in a trinitrobenzene sulfonic acid-induced colitis rat model. Tributyrin significantly mitigated intestinal inflammation, reduced pathological progression, and inhibited pyroptosis and cGAS-STING pathway activation in the colitis rat model. Similarly, in an in vitro model of IECs pyroptosis, sodium butyrate inhibited pyroptosis and cGAS-STING pathway activation in HT-29 cells. Co-treatment with a cGAS-STING pathway activator and butyrate demonstrated that the activator reversed the inhibitory effects of butyrate on pyroptosis and cGAS-STING pathway activation in both the colitis rat model and HT-29 cells. Mechanistically, the cGAS-STING pathway was found to interact with NLRP3. Taken together, butyrate may mitigate intestinal inflammation in CD by suppressing cGAS-STING-NLRP3 axis-mediated IECs pyroptosis. These findings offer new insights into potential therapeutic strategies for managing CD.

Unraveling the complexities of colorectal cancer and its promising therapies - An updated review

Colorectal cancer (CRC) continues to be a global health concern, necessitating further research into its complex biology and innovative treatment approaches. The etiology, pathogenesis, diagnosis, and treatment of colorectal cancer are summarized in this thorough review along with recent developments. The multifactorial nature of colorectal cancer is examined, including genetic predispositions, environmental factors, and lifestyle decisions. The focus is on deciphering the complex interactions between signaling pathways such as Wnt/β-catenin, MAPK, TGF-β as well as PI3K/AKT that participate in the onset, growth, and metastasis of CRC. There is a discussion of various diagnostic modalities that span from traditional colonoscopy to sophisticated molecular techniques like liquid biopsy and radiomics, emphasizing their functions in early identification, prognostication, and treatment stratification. The potential of artificial intelligence as well as machine learning algorithms in improving accuracy as well as efficiency in colorectal cancer diagnosis and management is also explored. Regarding therapy, the review provides a thorough overview of well-known treatments like radiation, chemotherapy, and surgery as well as delves into the newly-emerging areas of targeted therapies as well as immunotherapies. Immune checkpoint inhibitors as well as other molecularly targeted treatments, such as anti-epidermal growth factor receptor (anti-EGFR) as well as anti-vascular endothelial growth factor (anti-VEGF) monoclonal antibodies, show promise in improving the prognosis of colorectal cancer patients, in particular, those suffering from metastatic disease. This review focuses on giving readers a thorough understanding of colorectal cancer by considering its complexities, the present status of treatment, and potential future paths for therapeutic interventions. Through unraveling the intricate web of this disease, we can develop a more tailored and effective approach to treating CRC.

Effect of hyperglycemia on lung microbiota and treatment outcome in pulmonary tuberculosis: A scoping review

The comorbidity due to pulmonary tuberculosis (TB) and diabetes mellitus (DM) is a global health problem, but its mechanism remains unclear. It is suspected that hyperglycemic alteration of the immune response to TB and the composition of the lung microbiota play an important role. This scoping review aimed to contribute to the understanding of the mechanisms by mapping evidence on the effect of hyperglycemia on physical health indicators, immune cell counts, cytokine levels, and the composition of lung microbiota in patients with the DM-TB comorbidity. A systematic search for research articles about the relationship between hyperglycemia and physical health, immune cells, and cytokine levels in humans was conducted in MEDLINE, Scopus, and CINAHL Plus. Then, articles on the interactions between the immune cells, cytokines, and lung microbiota were identified through Google Scholar and Google search engines. Characteristics of the studies focusing on effects of hyperglycemia, the findings of the articles relevant to the research objectives, and strengths and weaknesses of the selected articles were charted in a data extraction tool. Twenty-one articles on the effects of hyperglycemia on immune mediators and health outcomes of patients with DM-TB were included. The evidence showed hyperglycemia to be associated with unfavorable treatment outcomes; altered counts and functioning of dendritic cells, monocytes, and CD4+ T cells; and changes in cytokine levels (mainly INF-γ, IL-17, IL-1β, IL-2, IL-6, IL-10, and TNF-α) in patients with DM-TB. The composition of the lung microbiota changed in correlation with changes in physical health outcomes, counts of immune cells, and cytokine levels. Thus, hyperglycemia, immune responses, and dysbiosis of the lung microbiota are integral in the pathogenesis of DM-TB and TB treatment outcomes. A prospective cohort study, especially in individuals with newly diagnosed DM versus known DM and concomitant latent TB versus active TB, is recommended to define causal relationships.

The Role of Innate Priming in Modifying Tumor-associated Macrophage Phenotype

Tumor-associated macrophages (TAMs) are innate immune cells that exert far reaching influence over the tumor microenvironment (TME). Depending on cues within the local environment, TAMs may promote tumor angiogenesis, cancer cell invasion and immunosuppression, or, alternatively, inhibit tumor progression via neoantigen presentation, tumoricidal reactive oxygen species generation and pro-inflammatory cytokine secretion. Therefore, TAMs have a pivotal role in determining tumor progression and response to therapy. TAM phenotypes are driven by cytokines and physical cues produced by tumor cells, adipocytes, fibroblasts, pericytes, immune cells, and other cells within the TME. Research has shown that TAMs can be primed by environmental stimuli, adding another layer of complexity to the environmental context that determines TAM phenotype. Innate priming is a functional consequence of metabolic and epigenetic reprogramming of innate cells by a primary stimulant, resulting in altered cellular response to future secondary stimulation. Innate priming offers a novel target for development of cancer immunotherapy and improved prognosis of disease, but also raises the risk of exacerbating existing inflammatory pathologies. This review will discuss the mechanisms underlying innate priming including metabolic and epigenetic modification, its relevance to TAMs and tumor progression, and possible clinical implications for cancer treatment.

Gut microbiota as a modulator of type 1 diabetes: A molecular perspective

Type 1 diabetes (T1D) is defined as an autoimmune metabolic disorder, characterized by destruction of pancreatic β-cells and high blood sugar levels. If left untreated, T1D results in severe health complications, including cardiovascular and kidney disease, as well as nerve damage, with ultimately grave consequences. Besides the role of genetic and certain environmental factors in T1D development, in the last decade, one new player emerged to affect T1D pathology as well, and that is a gut microbiota. Dysbiosis of gut bacteria can contribute to T1D by gut barrier disruption and the activation of autoimmune response, leading to the destruction of insulin producing cells, causing the development and aggravation of T1D symptoms. The relationship between gut microbiota and diabetes is complex and varies between individuals and additional research is needed to fully understand the effects of gut microbiome alternations in T1D pathogenesis. Therefore, the goal of this review is to understand the current knowledge in underlying molecular mechanism of gut microbiota effects, which leads to the new approaches for further studies in the prevention and treatment of T1D.

Causality between gut microbiota, immune cells, and breast cancer: Mendelian randomization analysis

The association between gut microbiota (GM) and breast cancer (BC) has been studied. Nevertheless, the causal relationship between them and the potential mediating factors have not been clearly defined. Therefore, in this study, Mendelian randomization analysis (MR) was employed to explore the causal relationship between 473 GM and BC, as well as the mediating effect of potential immune cells. In this investigation, we availed ourselves of the publicly accessible summary statistics from the genome-wide association study to undertake two-sample and reverse Mendelian randomization analyses on GM and BC, with the intention of clarifying the causal association between GM and BC. Subsequently, through the application of the two-step Mendelian randomization analysis, it was revealed that the relationship between GM and BC was mediated by immune cells. The stability of the research outcomes was verified via sensitivity analysis. Mendelian randomization analysis elucidated the protective impacts of 8 genera on BC (such as Phylum Actinobacteriota, Species Bacteroides A plebeius A, Species Bifidobacterium adolescentis, Species CAG-841 sp002479075, Family Fibrobacteraceae, Order Fibrobacterales, Class Fibrobacteria, and Species Phascolarctobacterium sp003150755). Additionally, there are 23 immune cell traits related to BC. Our research findings showed that the species Megamonas funiformis was associated with an increased risk of BC, and 11.20% of this effect was mediated by CD38 on IgD+ CD24-. Likewise, HLA DR on CD33br HLA DR+ CD14- mediated the causal relationship between Species Prevotellamassilia and BC, having a mediating ratio of 7.89%. This study clarifies a potential causal relationship between GM, immune cells, and BC and provides genetic evidence for this causal connection. It offers research directions for the subsequent prevention and treatment of BC through the interaction between GM and immune cells, and provides a reference for future mechanistic and clinical studies in this field.

Targeting gut microbiota as a therapeutic target in T2DM: A review of multi-target interactions of probiotics, prebiotics, postbiotics, and synbiotics with the intestinal barrier

The global epidemic of type 2 diabetes mellitus (T2DM) imposes a substantial burden on public health and healthcare expenditures, thereby driving the pursuit of cost-effective preventive and therapeutic strategies. Emerging evidence suggests a potential association between dysbiosis of gut microbiota and its metabolites with T2DM, indicating that targeted interventions aimed at modulating gut microbiota may represent a promising therapeutic approach for the management of T2DM. In this review, we concentrated on the multifaceted interactions between the gut microbiota and the intestinal barrier in the context of T2DM. We systematically summarized that the imbalance of beneficial gut microbiota and its metabolites may constitute a viable therapeutic approach for the management of T2DM. Meanwhile, the mechanisms by which gut microbiota interventions, such as probiotics, prebiotics, postbiotics, and synbiotics, synergistically improve insulin resistance in T2DM are summarized. These mechanisms include the restoration of gut microbiota structure, upregulation of intestinal epithelial cell proliferation and differentiation, enhancement of tight junction protein expression, promotion of mucin secretion by goblet cells, and the immunosuppressive functions of regulatory T cells (Treg) and M2 macrophages. Collectively, these actions contribute to the amelioration of the body's metabolic inflammatory status. Our objective is to furnish evidence that supports the clinical application of probiotics, prebiotics, and postbiotics in the management of T2DM.

Causal Link between Gut Microbiota and Infertility: A Two-sample Bidirectional Mendelian Randomization Study

OBJECTIVE

To investigate the associations of the gut microbiota with reproductive system diseases, including female infertility, male infertility, polycystic ovary syndrome (PCOS), primary ovarian failure, endometriosis, uterine fibroids, uterine polyps, sexual dysfunction, orchitis, and epididymitis.

METHODS

A two-sample bidirectional Mendelian randomization (MR) analysis was performed to evaluate the potential causal relationship between the composition of gut microbiota and infertility, along with associated diseases.

RESULTS

Sixteen strong causal associations between gut microbes and reproductive system diseases were identified. Sixty-one causal associations between gut microbes and reproductive system diseases were determined. The genus Eubacterium hallii was a protective factor against premature ovarian failure and a pathogenic factor of endometriosis. The genus Erysipelatoclostridium was the pathogenic factor of many diseases, such as PCOS, endometriosis, epididymitis, and orchitis. The genus Intestinibacter is a pathogenic factor of male infertility and sexual dysfunction. The family Clostridiaceae 1 was a protective factor against uterine polyps and a pathogenic factor of orchitis and epididymitis. The results of reverse causal association analysis revealed that endometriosis, orchitis, and epididymitis all led to a decrease in the abundance of bifidobacteria and that female infertility-related diseases had a greater impact on gut microbes than male infertility-related diseases did.

CONCLUSIONS

The findings from the MR analysis indicate that there is a bidirectional causal relationship between the gut microbiota and infertility as well as associated ailments. Compared with ovarian diseases, uterine diseases are more likely to lead to changes in women's gut microbiota. The findings of this research offer valuable perspectives on the mechanism and clinical investigation of reproductive system diseases caused by microorganisms.

Microbiota-derived butyrate inhibits cDC development via HDAC inhibition, diminishing their ability to prime T cells

Conventional dendritic cells (cDC) are central to maintaining the balance between protective immune responses and tolerance to harmless antigens, especially in the intestine. Short chain fatty acids (SCFAs) such as butyrate play critical roles in regulating intestinal immunity, but the underlying mechanisms remain unclear. Here we demonstrate that microbiota-derived butyrate alters intestinal cDC populations in vivo resulting in decreased numbers of the cDC2 lineage. By establishing a novel in vitro culture model, we show that butyrate has a direct and selective ability to repress the development of cDC2 from cDC precursors, an effect that is independent of G-protein coupled receptors (GPCRs) and is due to inhibition of histone deacetylase 3. Finally, cDC derived from pre-cDC in the presence of butyrate in vitro express lower levels of costimulatory molecules and have a decreased ability to prime naïve T cells. Together, our data show that butyrate affects the developmental trajectory of cDC, selectively repressing the cDC2 lineage and reducing their ability to stimulate T cells. These properties may help explain the ability of butyrate to maintain homeostasis in the intestine.

Gut dysbiosis was inevitable, but tolerance was not: temporal responses of the murine microbiota that maintain its capacity for butyrate production correlate with sustained antinociception to chronic morphine

The therapeutic benefits of opioids are compromised by the development of analgesic tolerance, which necessitates higher dosing for pain management thereby increasing the liability for drug dependence and addiction. Rodent models indicate opposing roles of the gut microbiota in tolerance: morphine-induced gut dysbiosis exacerbates tolerance, whereas probiotics ameliorate tolerance. Not all individuals develop tolerance which could be influenced by differences in microbiota, and yet no study design has capitalized upon this natural variation. We leveraged natural behavioral variation in a murine model of voluntary oral morphine self-administration to elucidate the mechanisms by which microbiota influences tolerance. Although all mice shared similar morphine-driven microbiota changes that largely masked informative associations with variability in tolerance, our high-resolution temporal analyses revealed a divergence in the progression of dysbiosis that best explained sustained antinociception. Mice that did not develop tolerance maintained a higher capacity for production of the short-chain fatty acid (SCFA) butyrate known to bolster intestinal barriers and promote neuronal homeostasis. Both fecal microbial transplantation (FMT) from donor mice that did not develop tolerance and dietary butyrate supplementation significantly reduced the development of tolerance independently of suppression of systemic inflammation. These findings could inform immediate therapies to extend the analgesic efficacy of opioids.

Immunosenescence: Aging and Immune System Decline

Immunosenescence, a systematic reduction in the immune system connected with age, profoundly affects the health and well-being of elderly individuals. This review outlines the hallmark features of immunosenescence, including thymic involution, inflammaging, cellular metabolic adaptations, and hematopoietic changes, and their impact on immune cells such as macrophages, neutrophils, T cells, dendritic cells, B cells, and natural killer (NK) cells. Thymic involution impairs the immune system's capacity to react to novel antigens by reducing thymopoiesis and shifting toward memory T cells. Inflammaging, characterized by chronic systemic inflammation, further impairs immune function. Cellular metabolic adaptations and hematopoietic changes alter immune cell function, contributing to a diminished immune response. Developing ways to reduce immunosenescence and enhance immunological function in the elderly population requires an understanding of these mechanisms.

Short-chain fatty acids are a key mediator of gut microbial regulation of T cell trafficking and differentiation after traumatic brain injury

The gut microbiota has emerged as a pivotal regulator of host inflammatory processes after traumatic brain injury (TBI). However, the mechanisms by which the gut microbiota communicates to the brain in TBI are still under investigation. We previously reported that gut microbiota depletion (GMD) using antibiotics after TBI resulted in increased microglial activation, reduced neurogenesis, and reduced T cell infiltration. In the present study, we have demonstrated that intestinal T cells contribute to the pool of cells infiltrating the brain after TBI. Depletion or genetic deletion of T cells before injury reversed GMD induced reductions in post-TBI neurogenesis. Short-chain fatty acid supplementation increased T regulatory and T helper1 cell infiltration to the brain along with restoring neurogenesis and microglia activation after TBI with GMD. These data suggest that T cell subsets are essential cellular mediators by which the gut microbiota modulates TBI pathogenesis, a finding with important therapeutic implications.

Unraveling the Role of the Human Gut Microbiome in Health and Diseases

The human gut is a complex ecosystem that supports billions of living species, including bacteria, viruses, archaea, phages, fungi, and unicellular eukaryotes. Bacteria give genes and enzymes for microbial and host-produced compounds, establishing a symbiotic link between the external environment and the host at both the gut and systemic levels. The gut microbiome, which is primarily made up of commensal bacteria, is critical for maintaining the healthy host's immune system, aiding digestion, synthesizing essential nutrients, and protecting against pathogenic bacteria, as well as influencing endocrine, neural, humoral, and immunological functions and metabolic pathways. Qualitative, quantitative, and/or topographic shifts can alter the gut microbiome, resulting in dysbiosis and microbial dysfunction, which can contribute to a variety of noncommunicable illnesses, including hypertension, cardiovascular disease, obesity, diabetes, inflammatory bowel disease, cancer, and irritable bowel syndrome. While most evidence to date is observational and does not establish direct causation, ongoing clinical trials and advanced genomic techniques are steadily enhancing our understanding of these intricate interactions. This review will explore key aspects of the relationship between gut microbiota, eubiosis, and dysbiosis in human health and disease, highlighting emerging strategies for microbiome engineering as potential therapeutic approaches for various conditions.

Short-chain fatty acids reverses gut microbiota dysbiosis-promoted progression of glioblastoma by up-regulating M1 polarization in the tumor microenvironment

Glioblastoma (GBM), known as the most malignant and common primary brain tumor of the central nervous system, has finite therapeutic options and a poor prognosis. Studies have shown that host intestinal microorganisms play a role in the immune regulation of parenteral tumors in a number of different ways, either directly or indirectly. However, the potential impact of gut microbiota on tumor microenvironment, particularly glioma immunological milieu, has not been clarified exactly. In this study, by using an orthotopic GBM model, we found gut microbiota dysbiosis caused by antibiotic cocktail treatment boosted the tumor process in vivo. An obvious change that followed gut microbiota dysbiosis was the enhanced percentage of M2-like macrophages in the TME, in parallel with a decrease in the levels of gut microbial metabolite, short-chain fatty acids (SCFAs) in the blood and tumor tissues. Oral supplementation with SCFAs can increase the proportion of M1-like macrophages in the TME, which improves the outcomes of glioma. In terms of mechanism, SCFAs-activated glycolysis in the tumor-associated macrophages may be responsible for the elevated M1 polarization in the TME. This study will enable us to better comprehend the "gut-brain" axis and be meaningful for the development of TAM-targeting immunotherapeutic strategies for GBM patients.

Gut Microbiota and Immune System Dynamics in Parkinson's and Alzheimer's Diseases

The gut microbiota, a diverse collection of microorganisms in the gastrointestinal tract, plays a critical role in regulating metabolic, immune, and cognitive functions. Disruptions in the composition of these microbial communities, termed dysbiosis, have been linked to various neurodegenerative diseases (NDs), such as Parkinson's disease (PD) and Alzheimer's disease (AD). One of the key pathological features of NDs is neuroinflammation, which involves the activation of microglia and peripheral immune cells. The gut microbiota modulates immune responses through the production of metabolites and interactions with immune cells, influencing the inflammatory processes within the central nervous system. This review explores the impact of gut dysbiosis on neuroinflammation, focusing on the roles of microglia, immune cells, and potential therapeutic strategies targeting the gut microbiota to alleviate neuroinflammatory processes in NDs.

Transcription factor ETV4 plays a critical role in the development of non-alcoholic fatty liver disease

The Angiopoietin-like 4 (ANGPTL4) and ETS Variant Transcription Factor 4 (ETV4) are involved in the metabolic transition and carcinogenesis in the liver. However, the role of ETV4 in the development of non-alcoholic fatty liver disease (NAFLD) is currently unknown. Our study reveals that ETV4 expression was upregulated in the diet-induced non-alcoholic fatty liver disease, and plays a critical role in the dysregulated lipid metabolism. We demonstrate a mechanism by which ANGPTL4 regulates lipid homeostasis via involving the AMPK/ETV4 axis. Transient knockdown of ETV4 abolished the ANGPTL4-induced expression of Srebp1c, Acc and Fasn. Insulin treatment potentially increased the physical association of ETV4 with SREBP1, and promotes nuclear translocation and transcriptional activity of SREBP1. In addition, we show that combined therapy with omega-3 fatty acids and diacylglycerol O-acyltransferase inhibitor 1 (DGAT1) inhibitor (A-922500) counteracted the ANGPTL4-ETV4 axis-induced lipogenesis in vitro, and in vivo in obese mice via activation of GPR120-βarrestin2-AMPK pathway. Finally, we demonstrate that targeted pharmacologic therapy using GalNac-ETV4 siRNA that specifically inhibits ETV4 gene expression in the liver protects against diet-induced NAFLD, obesity and dyslipidemia. Hence, our study reveal previously unrecognized role of ETV4 in the NAFLD, and provides rationale targeting ETV4 to treat NAFLD.