The microbial metabolites, short-chain fatty acids, regulate colonic Treg cell homeostasis

Anticancer Potential of Prebiotics: Targeting Estrogen Receptors and PI3K/AKT/mTOR in Breast Cancer

Estrogen receptors (ERs) play a critical role in breast cancer (BC) development and progression, with ERα being oncogenic and ERβ exhibiting tumor-suppressive properties. The interaction between ER signaling and other molecular pathways, such as PI3K/AKT/mTOR, influences tumor growth and endocrine resistance. Emerging research highlights the role of prebiotics in modulating gut microbiota, which may influence estrogen metabolism, immune function, and therapeutic responses in BC. This review explores the impact of prebiotics on estrogen receptor modulation, gut microbiota composition, immune regulation, and metabolic pathways in breast cancer. The potential of prebiotics as adjunctive therapies to enhance treatment efficacy and mitigate chemotherapy-related side effects is discussed. A comprehensive analysis of recent preclinical and clinical studies was conducted, examining the role of prebiotics in gut microbiota modulation, immune regulation, and metabolic reprogramming in breast cancer. The impact of short-chain fatty acids (SCFAs) derived from prebiotic fermentation on epigenetic regulation and endocrine resistance was also evaluated. Prebiotics were found to modulate the gut microbiota-estrogen axis, reduce inflammation, and influence immune responses. SCFAs demonstrated selective estrogen receptor downregulation and metabolic reprogramming, suppressing tumor growth. Synbiotic interventions mitigate chemotherapy-related side effects, improving the quality of life in breast cancer patients. Prebiotics offer a promising avenue for breast cancer prevention and therapy by modulating estrogen metabolism, immune function, and metabolic pathways. Future clinical trials are needed to validate their efficacy as adjunctive treatments in breast cancer management.

A systematic review on the role of gut microbiome in inflammatory bowel disease: Spotlight on virome and plant metabolites

Inflammatory bowel diseases (IBD), including ulcerative colitis and Crohn's disease, arise from various factors such as dietary, genetic, immunological, and microbiological influences. The gut microbiota plays a crucial role in the development and treatment of IBD, though the exact mechanisms remain uncertain. Current research has yet to definitively establish the beneficial effects of the microbiome on IBD. Bacteria and viruses (both prokaryotic and eukaryotic) are key components of the microbiome uniquely related to IBD. Numerous studies suggest that dysbiosis of the microbiota, including bacteria, viruses, and bacteriophages, contributes to IBD pathogenesis. Conversely, some research indicates that bacteria and bacteriophages may positively impact IBD outcomes. Additionally, plant metabolites play a crucial role in alleviating IBD due to their anti-inflammatory and microbiome-modulating properties. This systematic review discusses the role of the microbiome in IBD pathogenesis and evaluates the potential connection between plant metabolites and the microbiome in the context of IBD pathophysiology.

Machine learning determines the incidence of Alzheimer's disease based on population gut microbiome profile

The human microbiome is a complex and dynamic community of microbes, thought to have symbiotic benefit to its host. Influences of the gut microbiome on brain microglia have been identified as a potential mechanism contributing to neurodegenerative diseases, such as Alzheimer's disease, motor neurone disease and Parkinson's disease (Boddy SL, Giovannelli I, Sassani M, et al. The gut microbiome: A key player in the complexity of amyotrophic lateral sclerosis (ALS). BMC Med. 2021;19(1):13). We hypothesize that population level differences in the gut microbiome will predict the incidence of Alzheimer's disease using machine learning methods. Cross-sectional analyses were performed in R, using two large, open-access microbiome datasets (n = 959 and n = 2012). Countries in these datasets were grouped based on Alzheimer's disease incidence and the gut microbiome profiles compared. In countries with a high incidence of Alzheimer's disease, there is a significantly lower diversity of the gut microbiome (P < 0.05). A permutational analysis of variance test (P < 0.05) revealed significant differences in the microbiome profile between countries with high versus low incidence of Alzheimer's disease with several contributing taxa identified: at a species level Escherichia coli, and at a genus level Haemophilus and Akkermansia were found to be reproducibly protective in both datasets. Additionally, using machine learning, we were able to predict the incidence of Alzheimer's disease within a country based on the microbiome profile (mean area under the curve 0.889 and 0.927). We conclude that differences in the microbiome can predict the varying incidence of Alzheimer's disease between countries. Our results support a key role of the gut microbiome in neurodegeneration at a population level.

Total ginsenosides from wild ginseng improve immune regulation in a rat model of spleen qi deficiency by modulating fecal-bacteria-associated short-chain fatty acids and intestinal barrier integrity

For thousands of years, traditional Chinese medicine (TCM) has made extensive use of wild ginseng. It is thought to provide vital energy effects and to boost immunity. This study aimed to clarify the processes by which short-chain fatty acids (SCFAs) metabolites and the intestinal barrier are used by total ginsenosides wild ginseng (TWG) to modulate immunity. In this study, we analyzed and identified ginsenosides in the colon using UPLC-Q-TOF-MSE methods. In the meantime, a rat model of spleen qi deficiency (SQD) was created using reserpine, and the effects of TWG on intestinal barrier function and short-chain fatty acids in the feces of SQD-affected rats were examined. 28 ginsenosides were found in the colon during this experiment, and the main components were measured. TWG considerably increased fecal concentrations of acetic, propionic and 6 others, according to SCFAs analysis. According to serum immunological markers, TWG reduced IL-17 and IL-1β levels, increased IL-10, IL-22, and TGF-β concentrations, balanced Th17/Treg ratios, and reduced toxicants such DAO and LPS in rats with SQD. TWG improved barrier function, reduced permeability, increased tight junction protein expression, and lessened intestinal injury. A favorable correlation between intestinal barrier proteins and fatty acids was shown by correlation studies. The gut barrier and SCFAs perspectives helped to clarify the mechanism by which TWG controls immune activity. This study offers a fresh theoretical framework for TWG's future advancement and application.

Changes in gut microbiota predict neutropenia after induction treatment in childhood acute lymphoblastic leukemia

ABSTRACT

Delayed neutrophil recovery during acute lymphoblastic leukemia (ALL) treatment increases the risk of infection and causes delay in chemotherapy. Emerging evidence implicates gut microbiota in neutrophil reconstitution after chemotherapy. We explored the interplay between the gut microbiota and neutrophil dynamics, including neutrophil chemoattractants, in 51 children with newly diagnosed ALL. Daily absolute neutrophil count (ANC), weekly plasma chemokines (CXCL1 and CXCL8), granulocyte colony-stimulating factor (G-CSF), and fecal samples were monitored until day 29 during ALL induction treatment. Fecal sequencing using 16S ribosomal RNA revealed an overall significant reduction in bacterial diversity and Enterococcus overgrowth throughout the induction treatment. Prolonged neutropenia (ANC <0.5 × 109 cells per L at day 36) and elevated chemokine levels were associated with a decreased abundance of genera from the Ruminococcaceae and Lachnospiraceae families, decreased Veillonella genus, and Enterococcus overgrowth from diagnosis and throughout induction treatment. G-CSF was upregulated in response to neutropenia but was unrelated to microbiota changes. Overall, this study revealed that a diminished abundance of specific intestinal commensals and Enterococcus overgrowth is associated with delayed neutrophil reconstitution and increased chemokine signaling, indicating that disruption of the microbiota may contribute to prolonged neutropenia. These findings lay the groundwork for future investigations into the mechanisms underlying these associations and their clinical implications for developing gut-sparring strategies to minimize the impact of gut dysbiosis on immune recovery.

Gut microbiota and gastrointestinal tumors: insights from a bibliometric analysis

Introduction

Despite the growing number of studies on the role of gut microbiota in treating gastrointestinal tumors, the overall research trends in this field remain inadequately characterized.

Methods

A bibliometric analysis was conducted using publications retrieved from the Web of Science Core Collection (up to September 30, 2024). Analytical tools including VOSviewer, CiteSpace, and an online bibliometric platform were employed to evaluate trends and hotspots.

Results

Analysis of 1,421 publications revealed significant geographical disparities in research output, with China and the United States leading contributions. Institutionally, the University of Adelaide, Zhejiang University, and Shanghai Jiao Tong University were prominent contributors. Authorship analysis identified Hannah R. Wardill as the most prolific author, while the International Journal of Molecular Sciences emerged as a leading journal. Rapidly growing frontiers include "proliferation," "inhibition," "immunotherapy," "drug delivery," and "tumorigenesis."

Discussion

This study provides a comprehensive overview of research trends and highlights emerging directions, aiming to advance scientific and clinical applications of gut microbiota in gastrointestinal tumor therapy.

Optimizing Cancer Treatment Through Gut Microbiome Modulation

The gut microbiome plays a pivotal role in modulating cancer therapies, including immunotherapy and chemotherapy. Emerging evidence demonstrates its influence on treatment efficacy, immune response, and resistance mechanisms. Specific microbial taxa enhance immune checkpoint inhibitor efficacy, while dysbiosis can contribute to adverse outcomes. Chemotherapy effectiveness is also influenced by microbiome composition, with engineered probiotics and prebiotics offering promising strategies to enhance drug delivery and reduce toxicity. Moreover, microbial metabolites, such as short-chain fatty acids, and engineered microbial systems have shown potential to improve therapeutic responses. These findings underscore the importance of personalized microbiome-based approaches in optimizing cancer treatments.

Relationship between water-soluble primary metabolites in feces, gut microbiota, and dietary history in healthy female university students using gas chromatography-mass spectrometry: A cross-sectional study

Background & Aims: The ingested food substances and the substances produced by the action of organisms and gut bacteria on the ingested food can impact health and increase chronic disease risk. Metabolomics is used to elucidate metabolic profiles altered by diet; however, there is no clear consensus regarding the samples and the analytical and dietary survey methods used. This study aimed to assess the effect on metabolic profiling of feces with or without cell disruption and to evaluate the correlation between the annotated metabolites and the gut microbiota and dietary habits. Methods: This study included 50 healthy female university students. Metabolomic analysis using gas chromatography-mass spectrometry was performed under two conditions: with and without cell disruption. The annotated metabolites were designated as X1 and X2, respectively, and underwent principal component analysis (PCA). Orthogonal partial least squares regression (OPLS) analysis was performed between each metabolite and data on dietary habits and gut microbiota. Results: PCA using X1 and X2 metabolites showed generally consistent profiles of metabolites detected under the two extraction conditions. The OPLS analysis showed that the X1 metabolites were significantly associated with terms of α-diversity indices of the gut microbiota and with some food groups, whereas the X2 metabolites were significantly associated with only the α-diversity indices of the gut microbiota. Furthermore, using variable importance of projection values, several characteristic metabolites were detected in each significant OPLS model. Conclusion: For extraction of primary metabolites in feces, extraction methods without cell disruption may be strongly associated with food intake.

Roles of the gut microbiota in hepatocellular carcinoma: from the gut dysbiosis to the intratumoral microbiota

Hepatocellular carcinoma (HCC) is closely linked to alterations in the gut microbiota. This dysbiosis is characterized by significant changes in the microbial population, which correlate with the progression of HCC. Gut dysbiosis ultimately promotes HCC development in several ways: it damages the integrity of the gut-vascular barrier (GVB), alters the tumor microenvironment (TME), and even affects the intratumoral microbiota. Subsequently, intratumoral microbiota present a characteristic profile and play an essential role in HCC progression mainly by causing DNA damage, mediating tumor-related signaling pathways, altering the TME, promoting HCC metastasis, or through other mechanisms. Both gut microbiota and intratumoral microbiota have dual effects on HCC progression; a comprehensive understanding of their complex biological roles will provide a theoretical foundation for potential clinical applications in HCC treatment.

Gut microbiota-related modulation of immune mechanisms in post-infarction remodelling and heart failure

The immune system has long been recognized as a key driver in the progression of heart failure (HF). However, clinical trials targeting immune effectors have consistently failed to improve patient outcome across different HF aetiologies. The activation of the immune system in HF is complex, involving a broad network of pro-inflammatory and immune-modulating components, which complicates the identification of specific immune pathways suitable for therapeutic targeting. Increasing attention has been devoted to identifying gut microbial pathways that affect cardiac remodelling and metabolism and, thereby impacting the development of HF. In particular, gut microbiota-derived metabolites, absorbed by the host and transported to the peripheral circulation, can act as signalling molecules, influencing metabolism and immune homeostasis. Recent reports suggest that the gut microbiota plays a crucial role in modulating immune processes involved in HF. Here, we summarize recent advances in understanding the contributory role of gut microbiota in (auto-)immune pathways that critically determine the progression or alleviation of HF. We also thoroughly discuss potential gut microbiota-based intervention strategies to treat or decelerate HF progression.

Restorative Effects of Short-Chain Fatty Acids on Corneal Homeostasis Disrupted by Antibiotic-Induced Gut Dysbiosis

The gut microbiota plays a crucial regulatory role in various physiological processes, yet its impact on corneal homeostasis remains insufficiently understood. Here, the effects of antibiotic-induced gut dysbiosis (AIGD) and germ-free conditions were investigated on circadian gene expression, barrier integrity, nerve density, and immune cell activity in the corneas of mice. Both AIGD and germ-free conditions significantly disrupted the overall transcriptomic profile and circadian transcriptomic oscillations in the cornea, as indicated by RNA sequencing. These molecular disturbances were accompanied by a reduction in corneal epithelial thickness, nerve density, corneal sensitivity, and compromised barrier function. Notably, supplementation with short-chain fatty acids (SCFAs) significantly restored corneal integrity in AIGD mice. Further single-cell sequencing revealed that SCFA receptors G-protein-coupled receptor 109A (Hcar2), olfactory receptor 78 (Olfr78), and G-protein-coupled receptor 43 (Ffar2) are expressed in corneal epithelial basal cells, embryonically derived macrophages, perivascular cells, and γδ T cells, respectively. In conclusion, this study demonstrated that the gut microbiota plays a critical role in corneal physiology by regulating circadian gene expression and maintaining barrier function. These findings enhance our understanding of the gut-eye axis, highlighting the cornea as a target for microbiota-derived metabolic signals and underlining the potential therapeutic value of SCFAs in treating corneal dysfunction.

Altered gut microbiota and metabolite profiles in community-acquired pneumonia: a metagenomic and metabolomic study

Emerging evidence suggests that altered gut microbiota is linked to community-acquired pneumonia (CAP), but the potential mechanisms by which gut microbiota and its metabolites contribute to the development of CAP remain unclear. Fecal samples from 32 CAP patients and 36 healthy controls were analyzed through metagenomic sequencing and metabolomic profiling. The gut microbiota composition in CAP patients showed significant differences and lower diversity compared to healthy controls. Genera involved in short-chain fatty acid (SCFA) production, such as Faecalibacterium, Ruminococcus, and Eubacterium, as well as species like Faecalibacterium prausnitzii, Bifidobacterium adolescentis, Eubacterium rectale, Prevotella copri, and Ruminococcus bromii, were significantly depleted in CAP patients. Bacterial co-occurrence network analysis revealed an over-representation of pro-inflammatory bacteria, which contributed to the core gut microbiome in CAP patients. Metabolomic analysis of fecal samples identified a distinct metabolic profile, with a notable increase in arachidonic acid, but a decrease in secondary bile acids, such as deoxycholic acid, lithocholic acid, and ursodeoxycholic acid, compared to healthy controls. Spearman correlation analysis between differential microbiota and bile acids showed that Faecalibacterium prausnitzii, Bifidobacterium adolescentis, Eubacterium rectale, and Prevotella copri were positively correlated with ursocholic acid, lithocholic acid, and ursodeoxycholic acid, respectively. Our results suggest that the reduction in secondary bile acids, insufficient production of SCFAs, and an overabundance of pro-inflammatory bacteria may contribute to metabolic inflammation in the body. These factors could play a key role in the pathogenesis of CAP, driven by gut microbiota alterations.

IMPORTANCE

This study presents a comprehensive metagenomic and metabolomic analysis of fecal samples from community-acquired pneumonia (CAP) patients, identifying key characteristics, such as decreased secondary bile acids, imbalanced short-chain fatty acid production, and increased pro-inflammatory bacteria. These findings provide valuable insights into the mechanisms linking gut microbiota alterations to CAP pathogenesis and suggest that targeting the gut microbiota could be a promising strategy for intervening in CAP.

The gut-organ axis: Clinical aspects and immune mechanisms

The gut-brain axis exemplifies the bidirectional connection between the intestines and the brain, as evidenced by the impact of severe stress on gastrointestinal symptoms including abdominal pain and diarrhea, and conversely, the influence of abdominal discomfort on mood. Clinical observations support the notion of the gut-brain connection, including an increased prevalence of inflammatory bowel disease (IBD) in patients with depression and anxiety, as well as the association of changes in the gut microbiota with neurological disorders such as multiple sclerosis, Parkinson's disease, stroke and Alzheimer's disease. The gut and brain communicate via complex mechanisms involving inflammatory cytokines, immune cells, autonomic nerves, and gut microbiota, which contribute to the pathogenesis in certain gut and brain diseases. Two primary pathways mediate the bidirectional information exchange between the intestinal tract and the brain: signal transduction through bloodstream factors, such as bacterial metabolites and inflammatory cytokines, and neural pathways, such as neurotransmitters and inflammatory cytokines within the autonomic nervous system through the interaction between the nerve cells and beyond. In recent years, the basic mechanisms of the pathophysiology of the gut-brain axis have been gradually elucidated. Beyond the gut-brain interaction, emerging evidence suggests the influence of the gut extends to other organs, such as the liver and lungs, through intricate inter-organ communication pathways. An increasing number of reports on this clinical and basic cross-organ interactions underscore the potential for better understanding and novel therapeutic strategies targeting inter-organs networks. Further clarification of interactions between multiorgans premises transformative insights into cross-organ therapeutic strategies.

Lactobacillus acidophilus YL01 and its exopolysaccharides ameliorate obesity and insulin resistance in obese mice via modulating intestinal specific bacterial groups and AMPK/ACC signaling pathway

Probiotics intervention by Lactobacillus acidophilus has potential effect on alleviating obesity and insulin resistance. However, the limited knowledge of functional substances and potential regulatory mechanisms hinder their widespread application. Herein, L. acidophilus YL01 was firstly isolated from Chinese traditional yogurt, demonstrating inhibitory activities on amylase and glucosidase that are comparable to those of L. rhamnosus LGG. Besides, the oral administration of L. acidophilus YL01 and its EPS significantly reduced body weight in high-fat mice (p < 0.05), as well as fat accumulation in liver and adipocytes. Moreover, they not only reduced fasting blood glucose and glucose/insulin resistance, but also improved dyslipidemia, liver function and inflammation. Further high-performance liquid chromatography analysis and Fourier transform infrared spectroscopy indicated that EPS is an acidic polysaccharide, characterized by a molecular weight of 952 kDa and predominantly composed of glucose. Additionally, the mechanism investigation revealed that the L. acidophilus YL01 and EPS demonstrated limited efficacy in restoring the composition of gut microbiota, but rather exerted an influence on the abundance of specific bacterial groups. The enrichment of the bacterial groups resulted in the increase of acetic acid and butyric acid, which further mediates the gut-liver crosstalk in regulating lipid metabolism by the activation of AMPK/ACC pathway.

Understanding the microbiome as a mediator of bladder cancer progression and therapeutic response

Bladder cancer (BCa) remains a significant source of morbidity and mortality. BCa is one of the most expensive tumors to treat, in part because of a lack of nonsurgical options. The recent advent of immunotherapy, alone or in combination with other compounds, has improved therapeutic options. Resistance to immunotherapy remains common, and many patients do not have durable response. Recent advances indicate immunotherapy efficacy may be tied in part to the endogenous bacteria present in our body, more commonly referred to as the microbiome. Laboratory and clinical data now support the idea that a healthy microbiome is critical to effective response to immunotherapy. At the same time, pathogenic interactions between the microbiome and immune cells can also serve to drive formation of tumors, increasing the complexity of these interactions. Given the rising importance of immunotherapy in BCa, understanding how we might be able to alter the microbiome to improve therapeutic efficacy offers a novel route to improved patient care. The goal of this review is to examine our current understanding of microbial interactions with the immune system and cancer with an emphasis on BCa. We will further attempt to define both current gaps in knowledge and future directions that may yield beneficial results to the field.

The tumor microenvironment and dendritic cells: Developers of pioneering strategies in colorectal cancer immunotherapy?

Colorectal cancer (CRC) is the world's third most frequent cancer, and both its incidence and fatality rates are rising. Despite various therapeutic approaches, neither its mortality rate nor its recurrence frequency has decreased significantly. Additionally, conventional treatment approaches, such as chemotherapy and radiotherapy, have several side effects and risks for patients with CRC. Accordingly, the need for alternative and effective treatments for CRC patients is critical. Immunotherapy that utilizes dendritic cells (DCs) harnesses the patient's immune system to combat cancer cells effectively. DCs are the most potent antigen-presenting cells (APCs), which play a vital role in generating anti-cancer T cell responses. A significant barrier to the immune system's ability to eliminate CRC is the establishment of a potent immunosuppressive tumor milieu by malignant cells. Since DCs are frequently defective in this milieu, the tumor setting significantly reduces the effectiveness of DC-based therapy. Determining central mechanisms contributing to tumor growth by unraveling and comprehending the interaction between CRC tumor milieu and DCs may lead to new therapeutic approaches. This study aims to review DC biology and discuss its role in T-cell-mediated anti-tumor immunity, as well as to highlight the immunosuppressive effects of the CRC tumor milieu on the function of DCs. We will also highlight the tumor microenvironment (TME)-related factors that interfere with DC function as a possible therapeutic target to enhance DC-based cell therapy efficacy.

Colonic goblet cell-associated antigen passages mediate physiologic and beneficial translocation of live gut bacteria in preweaning mice

Gut-resident microorganisms have time-limited effects in distant tissues during early life. However, the reasons behind this phenomenon are largely unknown. Here, using bacterial culture techniques, we show that a subset of live gut-resident bacteria translocate and disseminate to extraintestinal tissues (mesenteric lymph nodes and spleen) in preweaning (day of life 17), but not adult (day of life 35), mice. Translocation and dissemination in preweaning mice appeared physiologic as it did not induce an inflammatory response and required host goblet cells, the formation of goblet cell-associated antigen passages, sphingosine-1-phosphate receptor-dependent leukocyte trafficking and phagocytic cells. One translocating strain, Lactobacillus animalisWU, showed antimicrobial activity against the late-onset sepsis pathogen Escherichia coli ST69 in vitro, and its translocation was associated with protection from systemic sepsis in vivo. While limited in context, these findings challenge the idea that translocation of gut microbiota is pathological and show physiologic and beneficial translocation during early life.

Oral tributyrin treatment affects short-chain fatty acid transport, mucosal health, and microbiome in a mouse model of inflammatory diarrhea

Butyrate may decrease intestinal inflammation and diarrhea. This study investigates the impact of oral application of sodium butyrate (NaB) and tributyrin (TB) on colonic butyrate concentration, SCFA transporter expression, colonic absorptive function, barrier properties, inflammation, and microbial composition in the colon of slc26a3-/- mice, a mouse model for inflammatory diarrhea. In vivo fluid absorption and bicarbonate secretory rates were evaluated in the cecum and mid-colon of slc26a3+/+ and slc26a3-/- mice before and during luminal perfusion of NaB-containing saline and were significantly stimulated in both slc26a3+/+ and slc26a3-/- colon by NaB. Age-matched slc26a3+/+ and slc26a3-/- mice were either fed chow containing 5% NaB or gavaged twice daily with TB for 21 d. Food and water intake, weight, and stool water content were assessed daily. Stool and tissues were collected for further analysis of SCFA production, barrier integrity, mucosal inflammation, and microbiome analysis by 16S rRNA gene sequencing. 5% NaB diet did not exert a significant impact on SCFA levels, mucus barrier, or inflammatory markers, but significantly increased oral water intake. TB gavage treatment increased the expression of SCFA transporters Mct1 and Smct1, mucus content and microbial diversity, and decreased the neutrophil marker Lipocalin 2, Phospholipase A2, and the antimicrobial peptide Reg3b in the slc26a3-/- cecum. However, TB treatment also resulted in an increase in inflammatory markers such as TNFα, Il-1β and CD3e in the wildtype mucosa. While there are some benefits with TB ingestion for barrier properties and microbial composition in the diseased cecum, potentially detrimental effects were noted in the healthy colon.

Modulation of Host Immunity by Microbiome-Derived Indole-3-Propionic Acid and Other Bacterial Metabolites

In recent years, we have witnessed a rapidly growing interest in the intricate communications between intestinal microorganisms and the host immune system. Research on the human microbiome is evolving from merely descriptive and correlative studies to a deeper mechanistic understanding of the bidirectional interactions between gut microbiota and the mucosal immune system. Despite numerous challenges, it has become increasingly evident that an imbalance in gut microbiota composition, known as dysbiosis, is associated with the development and progression of various metabolic, immune, cancer, and neurodegenerative disorders. A growing body of evidence highlights the importance of small molecules produced by intestinal commensal bacteria, collectively referred to as gut microbial metabolites. These metabolites serve as crucial diffusible messengers, translating the microbial language to host cells. This review aims to explore the complex and not yet fully understood molecular mechanisms through which microbiota-derived metabolites influence the activity of the immune cells and shape immune reactions in the gut and other organs. Specifically, we will discuss recent research that reveals the close relationship between microbial indole-3-propionic acid (IPA) and mucosal immunity. Furthermore, we will emphasize the beneficial effects of IPA on intestinal inflammation and discuss its potential clinical implications.

CaGA nanozymes inhibit oxidative stress and protect mitochondrial function in ulcerative colitis therapy

Ulcerative colitis (UC) is a long-term inflammatory bowel disease characterized by intense inflammation of the colorectal mucosa. Overproduction of reactive oxygen species exacerbates the progression of UC, which is linked to mitochondrial impairment and dysbiosis of the intestinal microbiota. CaGA nanozymes have demonstrated efficacy in the treatment of UC. The modulation of M1 and M2 polarization of macrophages by CaGA nanozymes has been demonstrated to be useful in reducing inflammation. Furthermore, CaGA nanozymes regulate the M1 and M2 polarization of macrophages, efficiently decreasing inflammation. The oral delivery of CaGA nanozymes resulted in their enrichment in inflamed areas of the colon and effectively reduced colonic damage in mice with DSS-induced colitis by improving the repair of the intestinal barrier. An investigation of 16S rDNA sequencing revealed that CaGA nanozymes regulate populations of both pathogenic and helpful bacteria and impact the progression of ulcerative colitis by influencing the tricarboxylic acid (TCA) cycle. Thus, CaGA nanozymes may be employed in the management of ulcerative colitis to control the intestinal milieu and improve the preservation of the intestinal barrier by decreasing the invasion of inflammatory cells and restoring mitochondrial activity. STATEMENT OF SIGNIFICANCE: CaGA nanozymes exhibit multifunctional enzymatic activity, effectively eliminating cellular RONS with robust antioxidant capacity. CaGA nanoenzymes promote macrophage M1 to M2 polarization and produce anti-inflammatory effects. CaGA nanozymes increase cell viability by restoring impaired mitochondrial function, reducing reactive oxygen species (ROS) production, and restoring the ability of mitochondria to produce ATP. CaGA nanozymes modulate intestinal flora diversity and composition, potentially influencing inflammatory pathways via aromatic compound metabolism. They participate in cellular energy and biosynthesis, regulating ulcerative colitis (UC)-related intestinal function through the tricarboxylic acid (TCA) and urea cycles. Calcium ions bind to GA nanomedicine and small particles are readily absorbed by inflammatory cells, preventing diarrhea from being rapidly excreted.

Deciphering T-cell exhaustion in the tumor microenvironment: paving the way for innovative solid tumor therapies

In solid tumors, the tumor microenvironment (TME) is a complex mix of tumor, immune, stromal cells, fibroblasts, and the extracellular matrix. Cytotoxic T lymphocytes (CTLs) constitute a fraction of immune cells that may infiltrate into the TME. The primary function of these T-cells is to detect and eliminate tumor cells. However, due to the immunosuppressive factors present in the TME primarily mediated by Myeloid-Derived Suppressor Cells (MDSCs), Tumor associated macrophages (TAMs), Cancer Associated Fibroblasts (CAFs) as well as the tumor cells themselves, T-cells fail to differentiate into effector cells or become dysfunctional and are unable to eliminate the tumor. In addition, chronic antigen stimulation within the TME also leads to a phenomenon, first identified in chronic lymphocytic choriomeningitis virus (LCMV) infection in mice, where the T-cells become exhausted and lose their effector functions. Exhausted T-cells (Tex) are characterized by the presence of remarkably conserved inhibitory receptors, transcription and signaling factors and the downregulation of key effector molecules. Tex cells have been identified in various malignancies, including melanoma, colorectal and hepatocellular cancers. Recent studies have indicated novel strategies to reverse T-cell exhaustion. These include checkpoint inhibitor blockade targeting programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin-domain containing-3 (Tim-3), cytotoxic T-lymphocyte associated protein 4 (CTLA-4), or combinations of different immune checkpoint therapies (ICTs) or combination of ICTs with cytokine co-stimulation. In this review, we discuss aspects of T-cell dysfunction within the TME with a focus on T-cell exhaustion. We believe that gaining insight into the mechanisms of T-cell exhaustion within the TME of human solid tumors will pave the way for developing therapeutic strategies to target and potentially re-invigorate exhausted T-cells in cancer.

Combining gut microbiota modulation and immunotherapy: A promising approach for treating microsatellite stable colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and lethal cancers worldwide, ranking third in incidence and second in mortality. While immunotherapy has shown promise in patients with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H), its effectiveness in proficient mismatch repair (pMMR) or microsatellite stable (MSS) CRC remains limited. Recent advances highlight the gut microbiota as a potential modulator of anti-tumor immunity. The gut microbiome can significantly influence the efficacy of immune checkpoint inhibitors (ICIs), especially in pMMR/MSS CRC, by modulating immune responses and systemic inflammation. This review explores the role of the gut microbiota in pMMR/MSS CRC, the mechanisms by which it may enhance immunotherapy, and current strategies for microbiota modulation. We discuss the potential benefits of combining microbiota-targeting interventions with immunotherapy to improve treatment outcomes for pMMR/MSS CRC patients.

Delivery of butyrate to the lower gut by polymeric micelles prolongs survival of distal skin allografts

The microbiota composition is known to influence the kinetics of graft rejection, but many questions remain as to whether/how microbiota-derived metabolites affect graft outcome. We investigated the effects of the short-chain fatty acid butyrate, a product of dietary fiber fermentation. Sustained intragastric administration of a micelle-based formulation of butyrate (butyrate micelle [ButM]) that releases its cargo in the lower gastrointestinal tract elevated cecal butyrate content and significantly prolonged minor-mismatched and major-mismatched skin allograft survival in mice. While ButM did not influence regulatory T cells or the adaptive alloimmune responses we tested, it modulated the myeloid cell compartment. At steady state, ButM treatment reduced the number of circulating Ly6ChiCD11b+ monocytes and other myeloid cells in secondary lymphoid organs and skin, altered their expression of genes involved in mitochondrial metabolism and key inflammatory processes, and reduced their ability to produce TNFa, likely via an indirect mechanism. ButM treatment also reduced numbers of graft-infiltrating monocytes but not T cells. Consistent with its critical effect on myeloid cells, ButM's extension of graft survival depended on the presence of CCR2+ cells. These findings imply that cecal ButM improves distal allograft outcomes by quantitatively and qualitatively modulating myeloid cells, thereby inhibiting the innate immune cell-mediated effector phase of alloimmunity.

Safety Assessment of Butyric Acid-Rich Triglyceride Oil: A Novel Palatable Formulation of Butyrate for the Pediatric Population

A novel, palatable butyric acid-rich triglyceride oil has been developed and is available as a food supplement for adults in the United States and Canada. A program of safety studies was conducted with butyric acid-rich triglyceride oil for the pediatric population. The oil was tested in a microbial reverse mutation assay Ames Test OECD471 (Organisation for Economic Co-operation and Development) in which all bacterial strains showed negative responses over the complete dose range in two independently repeated experiments. All values were within the laboratory historical control data ranges. Further, data from the human lymphocyte micronucleus assay (OECD487) in the presence or absence of a metabolic activator (S9-mix), the oil did not induce a biologically relevant increase in the number of binucleated cells with micronuclei; therefore, the oil is considered not to be clastogenic or aneugenic. In a 90-day rat repeat dose toxicity study (OECD408), there were no unscheduled deaths, no treatment-related clinical signs, or effects on body weight and body weight gain, food consumption, ophthalmology, FOB parameters (including motor activity), clinical chemistry including thyroid hormones, and sperm parameters. There were no related organ weight changes, macroscopic or microscopic findings. In an extended one-generation reproductive toxicology study (EOGRTS) OECD443, there were no biologically important changes in body weight or body weight gain observed in the P generation male rats during the dosing period. At the end of the dosing period, the mean body weights in the male rats were 98% and 98% of the control group value in the 3720 and 4650 mg/kg/day dose groups, respectively. No biologically important changes in maternal body weights or body weight gains were observed during the premating, gestation, or lactation periods at dose levels up to and including 4650 mg/kg/day. Clinical signs observed in the P generation males and females were within the historical data ranges and not test substance related. There were no test substance-related changes in any other tested outcomes analyzed in the P generation males and females at doses up to and including 4650 mg/kg/day. In the F1 Generation, preweaning clinical signs observed in the males and females were within the historical data ranges and not test article related. There were no statistically significant or biologically relevant abnormalities in any of the parameters analyzed throughout the preweaning period at maternal dose levels up to and including 4650 mg/kg/day. In the postweaning period, there were also no clinical signs observed in males and females; all were within the historical data ranges and not test article related. There were no statistically significant or biologically relevant abnormalities in any of the parameters analyzed throughout the postweaning period at maternal dose levels up to and including 4650 mg/kg/day including body weights. Taken together, data from these toxicity studies show that butyric acid-rich triglyceride oil is extremely safe with a "no observed adverse effect level" (NOAEL) considered to be 4650 mg/kg/day, the highest dose tested.

Dynamic changes in the gut microbiota play a critical role in age-associated cognitive dysfunction via SCFAs and LPS synthesis metabolic pathways during brain aging

BACKGROUND

Gut microbiota plays an essential role in cognitive dysfunction during aging. The aim of this study was to investigate the dynamic alterations in the gut microbiota and screen for key gut bacterial taxa correlated with age-associated cognitive dysfunction during natural aging.

METHODS

16S rRNA gene sequencing was performed to determine the composition of the gut microbiota in faecal samples from SAMR1 and SAMP8 mice, cognitively normal controls (NC), and patients with amnestic mild cognitive impairment (aMCI). Faecal microbiota transplantation (FMT) and GMrepo database were used to screen key gut microbiota associated with cognitive decline in aging mice and humans.

RESULTS

The composition of the gut microbiota dynamically changed during natural aging in SAMR1 and SAMP8 mice, as well as in healthy subjects of different ages extracted from the GMrepo database. FMT from SAMR1 to SAMP8 mice altered the gut microbiota composition and improved the cognitive impairment in SAMP8 mice. Key gut bacterial taxa, including Lactobacillus, Akkermansia, Clostridium, Oscillospira and Dorea, were screened and validated to correlate with aging-associated cognitive decline. The function of the key gut bacterial taxa predicted by PICRUSt2 indicated that the metabolic pathways related to short-chain fatty acids (SCFAs) and lipopolysaccharide (LPS) synthesis were involved in age-associated cognitive dysfunction during natural aging.

CONCLUSION

These results demonstrate that the composition of the gut microbiota changes dynamically during brain aging, with some key gut bacterial taxa playing critical roles in age-associated cognitive dysfunction through SCFAs and LPS synthesis metabolic pathways.

Microbiota-dependent modulation of intestinal anti-inflammatory CD4+ T cell responses

Barrier organs such as the gastrointestinal tract, lungs, and skin are colonized by diverse microbial strains, including bacteria, viruses, and fungi. These microorganisms, collectively known as the commensal microbiota, play critical roles in maintaining health by defending against pathogens, metabolizing nutrients, and providing essential metabolites. In the gut, commensal-derived antigens are frequently sensed by the intestinal immune system. Maintaining tolerance toward these beneficial microbial species is crucial, as failure to do so can lead to chronic inflammatory conditions like inflammatory bowel disease (IBD) and can even affect systemic immune or metabolic health. The immune system carefully regulates responses to commensals through various mechanisms, including the induction of anti-inflammatory CD4⁺ T cell responses. Foxp3⁺ regulatory T cells (Foxp3+ Tregs) and Type 1 regulatory T cells (Tr1) play a major role in promoting tolerance, as both cell types can produce the anti-inflammatory cytokine IL-10. In addition to these regulatory T cells, effector T cell subsets, such as Th17 cells, also adopt anti-inflammatory functions within the intestine in response to the microbiota. This process of anti-inflammatory CD4+ T cell induction is heavily influenced by the microbiota and their metabolites. Microbial metabolites affect intestinal epithelial cells, promoting the secretion of anti-inflammatory mediators that create a tolerogenic environment. They also modulate intestinal dendritic cells (DCs) and macrophages, inducing a tolerogenic state, and can interact directly with T cells to drive anti-inflammatory CD4⁺ T cell functionality. The disrupted balance of these signals may result in chronic inflammation, with broader implications for systemic health. In this review, we highlight the intricate interplays between commensal microorganisms and the immune system in the gut. We discuss how the microbiota influences the differentiation of commensal-specific anti-inflammatory CD4⁺ T cells, such as Foxp3⁺ Tregs, Tr1 cells, and Th17 cells, and explore the mechanisms through which microbial metabolites modulate these processes. We further discuss the innate signals that prime and commit these cells to an anti-inflammatory fate.

The role of polysaccharides in immune regulation through gut microbiota: mechanisms and implications

Polysaccharides, as complex carbohydrates, play a pivotal role in immune modulation and interactions with the gut microbiota. The diverse array of dietary polysaccharides influences gut microbial ecology, impacting immune responses, metabolism, and overall well-being. Despite their recognized benefits, there is limited understanding of the precise mechanisms by which polysaccharides modulate the immune system through the gut microbiota. A comprehensive search of Web of Science, PubMed, Google Scholar, and Embase up to May 2024 was conducted to identify relevant studies. This study employs a systematic approach to explore the interplay between polysaccharides and the gut microbiota, focusing on cytokine-mediated and short-chain fatty acid (SCFA)-mediated pathways. The findings underscore the significant role of polysaccharides in shaping the composition and function of the gut microbiota, thereby influencing immune regulation and metabolic processes. However, further research is necessary to elucidate the detailed molecular mechanisms and translate these findings into clinical applications.

The microbiota-gut-brain axis in myalgic encephalomyelitis/chronic fatigue syndrome: a narrative review of an emerging field

The intricate relationship between gut microbiota and the brain has emerged as a pivotal area of research, particularly in understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). This complex condition is characterized by debilitating fatigue, cognitive dysfunction, and a wide array of systemic manifestations, posing significant challenges for diagnosis and treatment. Recent studies highlight the microbiota-gut-brain axis as a crucial pathway in ME/CFS pathophysiology, suggesting that alterations in gut microbial composition may impact immune responses, neurochemical signaling, and neuronal health. This narrative review systematically explores English-language scholarly articles from January 1995 to January 2025, utilizing databases such as PubMed, Scopus, and Web of Science. The findings underscore the potential for targeted therapeutic interventions aimed at correcting gut dysbiosis. As research progresses, a deeper understanding of the microbiota-gut-brain connection could lead to innovative approaches for managing ME/CFS, ultimately enhancing the quality of life for affected individuals.

Decreased Lactococcus lactis and Propionic Acid in Feces of Patients with Moyamoya Disease: Possible Implications of Immune Dysregulation

INTRODUCTION

Moyamoya disease (MMD) is a cerebrovascular disease characterized by progressive steno-occlusive lesions in the terminal portion of the internal carotid artery. Despite its unknown etiology, immune dysregulation is regarded as a critical trigger for delineating the pathophysiology of MMD. The gut microbiota produces short-chain fatty (SCFA) and organic acids, influencing immune regulation and vascular remodeling. We aimed to characterize the gut microbiota in patients with MMD.

METHODS

Sixteen patients with MMD and sixteen healthy controls (CON) were included in this study. We performed 16S rRNA sequencing of fecal samples, analyzed microbiome diversity and composition, and quantified SCFA and organic acid levels using liquid chromatography.

RESULTS

There were no significant differences in α- and β-diversities among feces from the MMD patients and CON. However, 16S rRNA sequencing identified defective Lactococcus lactis (0 ± 0 in the MMD patients vs. 0.026 ± 0.084 in healthy CON, p = 0.0181) and abundant Gordinobacter pamelaeae (0.030 ± 0.039 in the patients vs. 0.001 ± 0.005 in healthy CON, p = 0.003) are strongly linked to MMD. Propionic acid levels were significantly lower in feces of the MMD patients compared to healthy CON (0.83 ± 0.34 mg/g in the MMD patients vs. 1.20 ± 0.55 mg/g in healthy CON, p = 0.028).

CONCLUSION

Decreased L. lactis can result in reduced lactic acid and propionic acid levels in the feces of the patients. This imbalance in the gut microbiome and SCFA/organic acid levels could contribute to immune dysregulation underlying the vascular remodeling seen in MMD.

De-coding the complex role of microbial metabolites in cancer

The human microbiome, an intricate ecosystem of trillions of microbes residing across various body sites, significantly influences cancer, a leading cause of morbidity and mortality worldwide. Recent studies have illuminated the microbiome's pivotal role in cancer development, either through direct cellular interactions or by secreting bioactive compounds such as metabolites. Microbial metabolites contribute to cancer initiation through mechanisms such as DNA damage, epithelial barrier dysfunction, and chronic inflammation. Furthermore, microbial metabolites exert dual roles on cancer progression and response to therapy by modulating cellular metabolism, gene expression, and signaling pathways. Understanding these complex interactions is vital for devising new therapeutic strategies. This review highlights microbial metabolites as promising targets for cancer prevention and treatment, emphasizing their impact on therapy responses and underscoring the need for further research into their roles in metastasis and therapy resistance.

Temporal dynamics of immune cell transcriptomics in brain metastasis progression influenced by gut microbiome dysbiosis

Interactions between metastatic cancer cells and the brain microenvironment regulate brain metastasis (BrMet) progression. Central nervous system (CNS)-native and peripheral immune cells influence the BrMet immune landscape, but the dynamics and factors modulating this microenvironment remain unclear. As the gut microbiome impacts CNS and peripheral immune activity, we investigated its role in regulating immune response dynamics throughout BrMet stages. Antibiotic-induced (ABX) gut dysbiosis significantly increased BrMet burden versus controls but was equalized with fecal matter transplantation, highlighting microbiome diversity as a regulator of BrMet. Single-cell sequencing revealed a highly dynamic immune landscape during BrMet progression in both conditions. However, the timing of the monocyte inflammatory response was altered. Microglia displayed an elevated activation signature in late-stage metastasis in ABX-treated mice. T cell and microglia perturbation revealed involvement of these cell types in modulating BrMet under gut dysbiosis. These data indicate profound effects on immune response dynamics imposed by gut dysbiosis across BrMet progression.

Fu Brick Tea Protects the Intestinal Barrier and Ameliorates Colitis in Mice by Regulating Gut Microbiota

Ulcerative colitis (UC) pathogenesis is strongly linked to gut microbiota dysbiosis and compromised intestinal barrier integrity. Emerging evidence suggests that targeted dietary interventions may restore microbial homeostasis and ameliorate colitis progression. In this study, we evaluated the therapeutic potential of Fu Brick tea (FBT) using a dextran sulfate sodium (DSS)-induced murine colitis model. The results indicated that oral administration of FBT extract significantly improved the disease index, reduced inflammatory response, protected intestinal barrier protein (e.g., ZO-1), and maintained intestinal structure integrity. Furthermore, FBT intake increased the diversity of gut microbiota, promoted the growth of beneficial bacteria (e.g., Akkermansia), inhibited the proliferation of harmful bacteria (e.g., Desulfovibrioceae, Escherichia, and Helicobacter), restored intestinal homeostasis, and alleviated colitis symptoms including diarrhea. These findings position FBT as a promising nutraceutical candidate for UC management via multi-target modulation of mucosal immunity and microbial ecology.

Comparative Analysis of Short-Chain Fatty Acids and the Immune Barrier in Cecum of Dahe Pigs and Dahe Black Pigs

The intestinal immune barrier is a developed and complex immune system, and there is a fine synergy between it and the induced immune response. Short-chain fatty acids (SCFAs) are the main metabolites of intestinal microbial fermentation. In the cecum of pigs, SCFAs not only provide energy for the host but also participate in regulating the function of the intestinal immune system. The purpose of this study was to explore the mechanism of SCFAs in the regulation of immune gene expression in porcine cecum. SCFAs content and mRNA expression levels of immune genes in cecum were detected, and Gene Ontology (GO) function annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, Protein-Protein Interaction Networks (PPI) network construction, key gene identification, and correlation analysis were performed. The results showed that the content of SCFAs in the cecum of Dahe black pigs (DHB) was lower than that of Dahe pigs (DH). There were significant differences in mRNA expression of some immune genes between the two groups. GO functional annotation found terms related to cytokine activity and protein heterodimerization activity; the KEGG pathway was enriched in several pathways related to intestinal immunity. The PPI network identified Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Interleukin-17A (IL-17A), and Interleukin-18 (IL-18) as key proteins. The correlation analysis showed that acetic acid and valerate were closely related to the immune response. In this study, the differences in cecal short-chain fatty acids and the immune barrier between Dahe pigs and Dahe black pigs were compared, which provided a theoretical basis for improving the intestinal immunity of pigs.

Optimizing Precision Probiotics for Mitigating Graft-Versus-Host Disease

Precision probiotics have shown great promise as novel therapies but have not been fully realized. One major obstacle is that different strains of the same gut microbiota species can induce markedly variable phenotypic outcomes. Here, we aimed to optimize and validate in a preclinical model, a six-species precision probiotic therapy for graft-versus-host disease (GVHD), an autoimmune complication following allogeneic stem cell transplantation. We had identified these six species as associated with protection against GVHD in a prior clinical study. We isolated strains of three of the targeted taxa (B. longum, C. bolteae, and Blautia spp.) from human stem cell transplant patients and characterized their SCFA production in vitro. We observed significant strain-to-strain variability among these gut microbiota taxa in their capacity to produce short-chain fatty acids, a microbiota-derived metabolite shown to be important for mitigating gut GVHD and inflammatory bowel disease, in vitro. We found that B. longum was able to augment butyrate production by C. bolteae and Blautia when co-cultured in vitro. "Optimized" precision probiotics mitigated GVHD and significantly increased survival (p = 0.013, log-rank test) in mice compared to a "standard" probiotic consortium of the same bacterial species obtained from a commercial repository. Importantly, the optimized probiotics resulted in significant increases in intestinal short-chain fatty acid concentrations compared to standard probiotics (p < 0.001, Mann-Whitney test). Our findings highlight the promising potential of utilizing an optimized precision probiotic approach to maximize therapeutic efficacy.

Restoring immune tolerance in pre-RA: immunometabolic dialogue between gut microbiota and regulatory T cells

Rheumatoid arthritis (RA) is a complex chronic autoimmune disease that remains incurable for most patients. With advances in our understanding of the disease's natural history, the concept of pre-RA has emerged as a window of opportunity to intervene before irreversible joint damage occurs. Numerous studies have indicated that the key step driving autoimmunity in early pre-RA lies at an extra-articular site, which is closely related to the regulatory T (Treg) cell-established immune tolerance to the gut microbiota. The intricate immunometabolic crosstalk between Treg cells and the gut microbiota is beginning to be understood, with the re-recognition of Treg cells as metabolic sensors in recent years. In the future, deciphering their immunometabolic dialogue may help to elucidate the underlying mechanisms of pre-RA. Identifying novel biological pathways in the pre-RA stage will bring insights into restoring immune tolerance, thereby potentially curing or preventing the onset of RA.

Compositional and Functional Profile of Gut Microbiota in a Cohort of Adult Spanish Patients with Atopic Dermatitis Using Metagenomics: A Cross-Sectional Study

Background: The role of gut dysbiosis in the pathophysiology of atopic dermatitis (AD) through immune system (IS) imbalance is a novel line of investigation currently under discussion. This study aimed to characterize compare the composition and functional profile of the gut microbiota (GM) between adults with AD and healthy individuals. Methods: Observational cross-sectional study, where fecal samples from 70 adults (38 patients and 32 controls) were analyzed using metagenomics and bioinformatics. Results: Differences between the GM of patients with AD and healthy individuals were demonstrated. Reduced microbial diversity was found in subjects with AD. Bacterial species with lower abundance primarily belonged to the families Ruminococcaceae, Akkermansiaceae, and Methanobacteriaceae. Several microbial metabolic pathways were found to be decreased in patients with AD, including amino acid biosynthesis, vitamin biosynthesis, fatty acids and lipids biosynthesis, and energy metabolism. Conclusion: Adults with AD exhibited a distinct GM compared to healthy individuals. Changes were demonstrated both compositionally and functionally. Further investigation is mandatory to elucidate the potential link and causal relationship between gut dysbiosis and AD, which may be crucial for a deeper understanding of the disease's pathophysiology and the development of novel therapeutic approaches.

Effects of psychological stress on inflammatory bowel disease via affecting the microbiota-gut-brain axis

ABSTRACT

Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory condition with chronic and relapsing manifestations and is characterized by a disturbance in the interplay between the intestinal microbiota, the gut, and the brain. The microbiota-gut-brain axis involves interactions among the nervous system, the neuroendocrine system, the gut microbiota, and the host immune system. Increasing published data indicate that psychological stress exacerbates the severity of IBD due to its negative effects on the microbiota-gut-brain axis, including alterations in the stress response of the hypothalamic-pituitary-adrenal (HPA) axis, the balance between the sympathetic nervous system and vagus nerves, the homeostasis of the intestinal flora and metabolites, and normal intestinal immunity and permeability. Although the current evidence is insufficient, psychotropic agents, psychotherapies, and interventions targeting the microbiota-gut-brain axis show the potential to improve symptoms and quality of life in IBD patients. Therefore, further studies that translate recent findings into therapeutic approaches that improve both physical and psychological well-being are needed.

Decoding Allergenicity Modulation in Cold Argon Plasma-Treated Casein: A Multi-Omics Exploration

Cold argon plasma (CAP) effectively modifies casein (CN) structures by cleaving peptide chains and altering allergenic epitopes. This study assessed the allergenicity of CAP-treated CN in KU812 cells and BALB/c mouse models, supported by a multiomics approach integrating 16S rDNA sequencing, serum metabolomics, and jejunal transcriptomics. CAP treatment reduced CN allergenicity, evidenced by decreased KU812 cell degranulation, alleviated allergic responses in mice, and a Th1/Th2 balance shift toward Th1 dominance. Furthermore, CAP-treated CN restored the gut microbiota equilibrium, increasing the number of beneficial bacteria. Multiomics analysis highlighted its impact on lipid metabolism pathways, with Zbp1 and Hbb-bt identified as potential regulators of allergic responses. These findings underscore the potential of cold argon plasma as an innovative strategy to reduce food allergenicity through multifaceted physiological mechanisms, offering promising therapeutic applications in food allergy management.

Revealing gut microbiota biomarkers associated with melanoma immunotherapy response and key bacteria-fungi interaction relationships: evidence from metagenomics, machine learning, and SHAP methodology

Introduction

The gut microbiota is associated with the response to immunotherapy in cutaneous melanoma (CM). However, gut fungal biomarkers and bacterial-fungal interactions have yet to be determined.

Methods

Metagenomic sequencing data of stool samples collected before immunotherapy from three independent groups of European ancestry CM patients were collected. After characterizing the relative abundances of bacteria and fungi, Linear Discriminant Analysis Effect Size (LEfSe) analysis, Random Forest (RF) model construction, and SHapley Additive exPlanations (SHAP) methodology were applied to identify biomarkers and key bacterial-fungal interactions associated with immunotherapy responders in CM.

Results

Diversity analysis revealed significant differences in the bacterial and fungal composition between CM immunotherapy responders and non-responders. LEfSe analysis identified 45 bacterial and 4 fungal taxa as potential biomarkers. After constructing the RF model, the AUC of models built using bacterial and fungal data separately were 0.64 and 0.65, respectively. However, when bacterial and fungal data were combined, the AUC of the merged model increased to 0.71. In the merged model, the following taxa were identified as important biomarkers: Romboutsia, Endomicrobium, Aggregatilinea, Candidatus Moduliflexus, Colwellia, Akkermansia, Mucispirillum, and Rutstroemia, which were associated with responders, whereas Zancudomyces was associated with non-responders. Moreover, the positive correlation interaction between Akkermansia and Rutstroemia is considered a key bacterial-fungal interaction associated with CM immunotherapy response.

Conclusion

Our results provide valuable insights for the enrichment of responders to immunotherapy in CM patients. Moreover, this study highlights the critical role of bacterial-fungal interactions in CM immunotherapy.

Mutual Interactions Between Microbiota and the Human Immune System During the First 1000 Days of Life

The development of the human immune system starts during the fetal period in a largely, but probably not completely, sterile environment. During and after birth, the immune system is exposed to an increasingly complex microbiota. The first microbiota encountered during passage through the birth canal colonize the infant gut and induce the tolerance of the immune system. Transplacentally derived maternal IgG as well as IgA from breast milk protect the infant from infections during the first 100 days, during which the immune system further develops and immunological memory is formed. The Weaning and introduction of solid food expose the immune system to novel (food) antigens and allow for other microbiota to colonize. The cells and molecules involved in the mutual and intricate interactions between microbiota and the developing immune system are now beginning to be recognized. These include bacterial components such as polysaccharide A from Bacteroides fragilis, as well as bacterial metabolites such as the short-chain fatty acid butyrate, indole-3-aldehyde, and indole-3-propionic acid. All these, and probably more, bacterial metabolites have specific immunoregulatory functions which shape the development of the human immune system during the first 1000 days of life.

Disturbances in the gut microbiota potentially associated with metabolic syndrome among patients living with HIV-1 and on antiretroviral therapy at Bafoussam Regional Hospital, Cameroon

BACKGROUND

This study investigates the gut microbiota components associated with metabolic syndrome in patients living with HIV-1 at Bafoussam Regional Hospital, West Cameroon, it focuses on gastrointestinal mucosal barrier disruption and dysbiosis, and their effects on persistent inflammation and metabolic disorders.

METHODS

A pilot study was conducted involving fourteen patients living with HIV-1. The patients were divided into two groups of seven in each group. One group consisted of patients with metabolic syndrome, and the other group included patients without metabolic syndrome. Gut microbiota was characterized using 16 S rRNA gene-targeted sequencing to analyze microbial diversity and composition. Beta diversity and the relative abundance of bacterial taxa were compared between patients with and without metabolic syndrome.

RESULTS

Patients living with HIV-1 and metabolic syndrome showed significantly altered beta diversity compared to those without metabolic syndrome. A higher relative abundance of Firmicutes and increased proliferation of Proteobacteria were observed in patients with metabolic syndrome. Additionally, a decrease in metabolically beneficial bacteria, such as Bifidobacterium sp., Lactobacillus sp., Akkermansia sp., and Faecalibacterium sp., was noted. Several beneficial bacterial species were associated with participants' metadata, suggesting potential links between gut microbiota and metabolic syndrome.

CONCLUSION

This preliminary study highlights that gut microbial balance, rather than the presence of specific bacteria, plays a crucial role in managing metabolic health in patients living with HIV-1. The altered gut microbiota in participants with metabolic syndrome emphasizes the need for further research into the optimal gut microbial structure. Understanding the interaction between gut microbiota changes and the chemical environment in these patients could guide targeted interventions to improve metabolic outcomes.

Single-cell and chromatin accessibility profiling reveals regulatory programs of pathogenic Th2 cells in allergic asthma

Lung pathogenic T helper type 2 (pTh2) cells are important in mediating allergic asthma, but fundamental questions remain regarding their heterogeneity and epigenetic regulation. Here we investigate immune regulation in allergic asthma by single-cell RNA sequencing in mice challenged with house dust mite, in the presence and absence of histone deacetylase 1 (HDAC1) function. Our analyses indicate two distinct highly proinflammatory subsets of lung pTh2 cells and pinpoint thymic stromal lymphopoietin (TSLP) and Tumour Necrosis Factor Receptor Superfamily (TNFRSF) members as important drivers to generate pTh2 cells in vitro. Using our in vitro model, we uncover how signalling via TSLP and a TNFRSF member shapes chromatin accessibility at the type 2 cytokine gene loci by modulating HDAC1 repressive function. In summary, we have generated insights into pTh2 cell biology and establish an in vitro model for investigating pTh2 cells that proves useful for discovering molecular mechanisms involved in pTh2-mediated allergic asthma.

The dual role of gut microbiota in pancreatic cancer: new insights into onset and treatment

Pancreatic cancer ranks among the most lethal digestive malignancies, exhibiting a steadily increasing incidence and mortality worldwide. Despite significant advances in cancer research, the 5-year survival rate remains below 10%, predominantly due to delayed diagnosis and limited therapeutic options. Concurrently, the gut microbiota-an integral component of host physiology-has emerged as a crucial player in the pathogenesis of pancreatic cancer. Mounting evidence indicates that alterations in gut microbial composition and function may influence tumor initiation, progression, and response to therapy. This review provides an in-depth examination of the intricate interplay between the gut microbiome and pancreatic cancer, highlighting potential diagnostic biomarkers and exploring microbiome-targeted therapeutic strategies to improve patient outcomes.

The role of microbiota in the chronic prostatitis/chronic pelvis pain syndrome: a review

Chronic prostatitis/Chronic pelvis pain syndrome (CP/CPPS), a kind of frequent urinary condition among adult males, has caused a lot of inconvenience to patients in life, whose pathogenesis is unclear. Current evidence suggests that it is most likely to be an autoimmune disease. Symbiotic microbes, a highly diverse biological community that harbors trillions of microbes in each region of the human body, have gradually made people realize their important role in immune regulation, material metabolism, and health maintenance. In recent years, increasing studies have shown a connection between microbiota and CP/CPPS. In view of this, we performed this review to summarize the literature pertaining to microbiota and its association with the pathophysiological mechanism of CP/CPPS. In addition, we gleaned the latest progress in the therapeutic strategy of CP/CPPS that related to microbiota regulation in order to offer new perspectives on the management of CP/CPPS.

Propionyl-CoA carboxylase subunit B regulates anti-tumor T cells in a pancreatic cancer mouse model

Most human pancreatic ductal adenocarcinoma (PDAC) are not infiltrated with cytotoxic T cells and are highly resistant to immunotherapy. Over 90% of PDAC have oncogenic KRAS mutations, and phosphoinositide 3-kinases (PI3Ks) are direct effectors of KRAS. Our previous study demonstrated that ablation of Pik3ca in KPC (KrasG12D; Trp53R172H; Pdx1-Cre) pancreatic cancer cells induced host T cells to infiltrate and completely eliminate the tumors in a syngeneic orthotopic implantation mouse model. Now, we show that implantation of Pik3ca-/- KPC (named αKO) cancer cells induces clonal enrichment of cytotoxic T cells infiltrating the pancreatic tumors. To identify potential molecules that can regulate the activity of these anti-tumor T cells, we conducted an in vivo genome-wide gene-deletion screen using αKO cells implanted in the mouse pancreas. The result shows that deletion of propionyl-CoA carboxylase subunit B gene (Pccb) in αKO cells (named p-αKO) leads to immune evasion, tumor progression, and death of host mice. Surprisingly, p-αKO tumors are still infiltrated with clonally enriched CD8+ T cells but they are inactive against tumor cells. However, blockade of PD-L1/PD1 interaction reactivated these clonally enriched T cells infiltrating p-αKO tumors, leading to slower tumor progression and improve survival of host mice. These results indicate that Pccb can modulate the activity of cytotoxic T cells infiltrating some pancreatic cancers and this understanding may lead to improvement in immunotherapy for this difficult-to-treat cancer.

Microbiota-Derived L-SeMet Potentiates CD8+ T Cell Effector Functions and Facilitates Anti-Tumor Responses

Extensive studies have shown that gut microbiota-derived metabolites can enhance the antitumor efficacy of immunotherapy by modulating host immune responses. However, the more comprehensive spectrum of such metabolites and their mechanisms remain unclear. In this study, we demonstrated that L-selenomethionine (L-SeMet), a gut microbial metabolite, acts as a positive regulator of immunotherapy. Through screening of a repository of gut microbial metabolites, we identified that L-SeMet can effectively enhance the effector function of CD8+ T cells. Furthermore, intragastric administration of L-SeMet in mice significantly suppressed the growth of subcutaneous MC38 tumors. Mechanistically, L-SeMet enhances T cell receptor (TCR) signaling by promoting LCK phosphorylation. Collectively, our findings reveal that the gut microbial metabolite L-SeMet inhibits colorectal tumor growth by potentiating CD8+ T cell functions, providing a potential therapeutic strategy for colorectal cancer treatment.

Microbiota in inflammatory bowel disease: mechanisms of disease and therapeutic opportunities

Perturbations in the intestinal microbiome are strongly linked to the pathogenesis of inflammatory bowel disease (IBD). Bacteria, fungi and viruses all make up part of a complex multi-kingdom community colonizing the gastrointestinal tract, often referred to as the gut microbiome. They can exert various effects on the host that can contribute to an inflammatory state. Advances in screening, multiomics and experimental approaches have revealed insights into host-microbiota interactions in IBD and have identified numerous mechanisms through which the microbiota and its metabolites can exert a major influence on the gastrointestinal tract. Looking into the future, the microbiome and microbiota-associated processes will be likely to provide unparalleled opportunities for novel diagnostic, therapeutic and diet-inspired solutions for the management of IBD through harnessing rationally designed microbial communities, powerful bacterial and fungal metabolites, individually or in combination, to foster intestinal health. In this Review, we examine the current understanding of the cross-kingdom gut microbiome in IBD, focusing on bacterial and fungal components and metabolites. We examine therapeutic and diagnostic opportunities, the microbial metabolism, immunity, neuroimmunology and microbiome-inspired interventions to link mechanisms of disease and identify novel research and therapeutic opportunities for IBD.

Supplementation with Rare Earth-Chitosan Chelate Improves Tibia Quality, Disease Resistance Capacity, and Performance in Nursery Pigs

The aim of this study was to investigate the effects on the tibia, liver, and gut, and on performance, when supplementing nursery pigs with different levels of rare earth-chitosan chelate (RECC). A total of 80 piglets, weaned at 7.67 ± 0.09 kg, were randomly assigned to groups RECC0 (RECC, 0 mg/kg diet), RECC200 (RECC, 200 mg/kg diet), RECC400 (RECC, 400 mg/kg diet), and RECC600 (RECC, 600 mg/kg diet), with four replicates in each group and five pigs per replicate during a 28 d experiment. Samples of the left hind tibia, serum, and feces were collected for analysis. The results indicated that, compared to pigs from group RECC0, pigs from group RECC200 presented with the following: a longer trabecular perimeter (p < 0.05), a larger trabecular area (p < 0.01), a higher trabecular number (p < 0.05), a smaller degree of trabecular separation (p < 0.01), and a lower number of osteoclasts (p < 0.01) in the tibia; higher abundances of beneficial fecal bacteria such as g_Prevotellaceae_NK3B31_group, g_UCG_005, g_Rikenellaceae_RC9_gut_group, g_Acetitomaculum, g_Glutamicibacter, g_Frisingicoccus, and g_Alistipes; higher (p < 0.01) serum levels of IgM, IgA, IgG, and IL-10; a lower (p < 0.01) serum concentration of TNF-α; a higher (p < 0.05) average daily gain and feed conversion ratio; and a lower (p < 0.01) incidence of diarrhea. The dietary addition of RECC contributes to improvements in tibia quality, gut health, and performance in nursery pigs.

BT1549 coordinates the in vitro IL-10 inducing activity of Bacteroides thetaiotaomicron

The intestine is home to a complex immune system that is engaged in mutualistic interactions with the microbiome that maintain intestinal homeostasis. A variety of immune-derived anti-inflammatory mediators have been uncovered and shown to be critical for maintaining these beneficial immune-microbiome relationships. Notably, the gut microbiome actively invokes the induction of anti-inflammatory pathways that limit the development of microbiome-targeted inflammatory immune responses. Despite the importance of this microbiome-driven immunomodulation, detailed knowledge of the microbial factors that promote these responses remains limited. We have previously established that the gut symbiont Bacteroides thetaiotaomicron stimulates the production of the anti-inflammatory cytokine IL-10 via soluble factors in a Toll-like receptor 2 (TLR2)-MyD88-dependent manner. Here, using TLR2 activity reporter cell lines, we show that the capacity of B. thetaiotaomicron to stimulate TLR2 activity was not critically dependent on either of the canonical heterodimeric forms of TLR2, TLR2/TLR1, or TLR2/TLR6, that typically mediate its function. Furthermore, biochemical manipulation of B. thetaiotaomicron-conditioned media suggests that IL-10 induction is mediated by a protease-resistant or non-proteogenic factor. We next uncovered that deletion of gene BT1549, a predicted secreted lipoprotein, significantly impaired the capacity of B. thetaiotaomicron to induce IL-10, while complementation in trans restored IL-10 induction, suggesting a role for BT1549 in the immunomodulatory function of B. thetaiotaomicron. Collectively, these data provide molecular insight into the pathways through which B. thetaiotaomicron operates to promote intestinal immune tolerance and symbiosis.

IMPORTANCE

Intestinal homeostasis requires the establishment of peaceful interactions between the gut microbiome and the intestinal immune system. Members of the gut microbiome, like the symbiont Bacteroides thetaiotaomicron, actively induce anti-inflammatory immune responses to maintain mutualistic relationships with the host. Despite the importance of such interactions, the specific microbial factors responsible remain largely unknown. Here, we show that B. thetaiotaomicron, which stimulates Toll-like receptor 2 (TLR2) to drive IL-10 production, can stimulate TLR2 independently of TLR1 or TLR6, the two known TLR that can form heterodimers with TLR2 to mediate TLR2-dependent responses. Furthermore, we show that IL-10 induction is likely mediated by a protease-resistant or non-proteogenic factor, and that this requires gene BT1549, a predicted secreted lipoprotein and peptidase. Collectively, our work provides insight into the molecular dialog through which B. thetaiotaomicron coordinates anti-inflammatory immune responses. This knowledge may facilitate future strategies to promote such responses for therapeutic purposes.