Bacteria-derived short-chain fatty acids as potential regulators of fungal commensalism and pathogenesis

Clostridium butyricum ameliorates post-gastrectomy insulin resistance by regulating the mTORC1 signaling pathway through the gut-liver axis

Postoperative insulin resistance (IR) is a metabolic disorder characterized by decreased insulin sensitivity and elevated blood glucose levels following major surgery. Our previous clinical study identified a notable correlation between postoperative IR and gut microbiota, particularly butyrate-producing bacteria, yet the mechanisms remain unclear. In this study, we established gastric resection SD rat models to evaluate the impact of Clostridium butyricum NCU-27 (butyrate-producing bacteria) on postoperative IR. The results demonstrated significant reductions in fasting blood glucose (FBG), fasting insulin (FIns) levels, and HOMA-IR (6.64 ± 0.76 vs. 11.47 ± 1.32; 4.27 ± 0.59 vs. 7.40 ± 0.54) in the postoperative period compared to the control group (P < 0.05). Additionally, glucose tolerance and hepatic glycogen content were markedly improved (P < 0.001). Further exploration of butyrate demonstrated effects similar to C. butyricum NCU-27, potentially mediated through the gut-liver axis by inhibiting mTORC1 expression in liver cells, activating the IRS1/AKT pathway, enhancing glucose uptake and glycogen synthesis, suppressing gluconeogenesis, increasing insulin sensitivity, and improving IR. Finally, the use of mTORC1 agonists and inhibitors further confirmed the critical role of the mTORC1 pathway in mediating the beneficial effects of C. butyricum NCU-27 and butyrate on postoperative IR. In conclusion, this study elucidated that C. butyricum NCU-27 improves postoperative IR by regulating butyrate metabolism and inhibiting the mTORC1 pathway, offering new insights for preventing and treating post-gastrectomy IR.

Use of postbiotics and parabiotics from lactobacilli in the treatment of infectious diarrhea

Probiotics are effective in the treatment of diarrheal disease which is the second leading cause of death in children below the age of five years via the production of antimicrobial peptides and lactic acid. These live bacteria are known to benefit the host by modulating their gut microbiome and competitively excluding pathogens from the gut. As probiotics are live microbial cells, their safety evaluation is a concern that shifts the focus from the usage of live cells to parabiotics and postbiotics. In recent years attempts have been made to study the efficacy of postbiotics and parabiotics against enteric pathogens. Enteric pathogens are the major cause of diarrhea resulting in watery stools and electrolyte imbalance. Among various gastrointestinal illnesses, 30 % are caused by bacteria. These gastrointestinal infections in adults have usually mild to moderate symptoms that disappear spontaneously but, in some cases, they can cause chronic diseases such as typhoid, irritable bowel syndrome, ulcerative colitis and bacteremia. The extensive use of antibiotics for the treatment of bacterial-infection-induced diarrhea has led to the emergence of drug resistance among these enteric pathogens. Drug resistance poses a major threat in the treatment of various other diseases as well. Further, the use of antibiotics is known to disrupt the homeostasis of the gut by killing the normal gut flora thereby worsening the situation. Therefore, the urgent need for new interventions to combat these enteric pathogens along with restoration of gut barrier. Lactobacillus-derived parabiotics and postbiotics have emerged as promising approaches for managing and treating diarrheal diseases. Therefore, our research is focused on studying the efficacy and underlying mechanisms of Lactobacillus spp.-derived postbiotics and parabiotics against enteric pathogens. Understanding these mechanisms helps in combatting diarrhea associated with enteric pathogens and results in reducing the morbidity and mortality rates associated with infectious diarrhea and its complications.

Skin mycobiome: Fungi drive colonization resistance in an already hostile environment

Fungi are an understudied part of the microbiome and can impact host physiology and maintenance of homeostasis. A new study explores how colonization resistance mediated by the fungal skin commensal Malassezia sympodialis exerts evolutionary pressures on Staphylococcus aureus.

Microplastics reduced the natural attenuation of antibiotic resistance genes in fertilized soils

The prolonged application of mulch and manure in agriculture has led to significant microplastic (MP) pollution in fertilized soils, raising global concerns about its potential impacts on soil health and ecosystem function. However, the effects of MP exposure on antibiotic resistance genes (ARGs) and microbial communities in fertilized soils are unknown. Therefore, we comprehensively explored the trends and drivers of ARGs during their natural abatement under the stress of conventional and biodegradable MP addition in fertilized soils using a soil microcosm experiment and metagenomic. The findings indicated that the presence of polybutylene succinate MPs (PBS-MPs) reduced the natural attenuation rate of ARGs in fertilized soils while increasing the fraction of high-risk ARGs in soils. Microbial communities and mobile genetic elements (MGEs) mainly drove the inhibitory effect of MPs on ARG abatement. Interestingly, most potential hosts for the coexistence of ARGs, metal resistance genes (MRGs), and MGEs were annotated as pathogens, such as Escherichia spp., Salmonella spp., and Klebsiella spp. In addition, MP stress in fertilized soil may lead to long-term contamination by highly virulent and antibiotic-resistant Escherichia coli. MPs influence the distribution of carbon sources, which in turn reduces the diversity and stability of soil microbial communities, while simultaneously promoting the colonization of crucial ARG hosts, like Dyella spp. This ultimately prolonged the high-risk state for ARG proliferation in the soil. This study highlights the significant risk posed by MPs to the persistence and spread of ARGs in fertilized soils. These results provide valuable insights for managing MP contamination in agricultural systems, emphasizing the need for sustainable practices to mitigate the long-term environmental risks associated with MP pollution.

The gastrointestinal mycobiome in inflammation and cancer: unraveling fungal dysbiosis, pathogenesis, and therapeutic potential

The gastrointestinal mycobiome, comprising diverse fungal species, plays a significant role in gastrointestinal carcinogenesis and inflammatory bowel disease (IBD) pathogenesis. Recent studies have demonstrated that dysbiosis of the gut mycobiome, characterized by an overrepresentation of pathogenic fungi such as Candida albicans and Aspergillus, correlates with increased inflammation and cancer risk. For instance, C. albicans has been shown to induce colonic inflammation through the activation of pattern recognition receptors and the release of pro-inflammatory cytokines, exacerbating IBD symptoms and potentially facilitating tumorigenesis. Additionally, metagenomic analyses have revealed distinct fungal signatures in colorectal cancer tissues compared to adjacent healthy tissues, highlighting the potential of fungi as biomarkers for disease progression. Mechanistically, gut fungi contribute to disease through biofilm formation, mycotoxin secretion (e.g., aflatoxins, candidalysin), pro-inflammatory cytokine induction (e.g., IL-1β, IL-17), and disruption of epithelial barriers-creating a tumor-promoting and inflammation-prone environment. Furthermore, the interplay between fungi and the bacterial microbiome can amplify inflammatory responses, contributing to chronic inflammation and cancer development. Fungal interactions with bacterial communities also play a synergistic role in shaping mucosal immune responses and enhancing disease severity in both cancer and IBD contexts. As research continues to elucidate these complex fungal-host and fungal-bacterial interactions, targeting the gut mycobiome may offer novel therapeutic avenues for managing IBD and gastrointestinal cancers, emphasizing the need for integrated, mechanistically informed approaches to microbiome research.

Commensalism and pathogenesis of Candida albicans at the mucosal interface

Fungi are important and often underestimated human pathogens. Infections with fungi mostly originate from the environment, from soil or airborne spores. By contrast, Candida albicans, one of the most common and clinically important fungal pathogens, permanently exists in the vast majority of healthy individuals as a member of the human mucosal microbiota. Only under certain circumstances will these commensals cause infections. However, although the pathogenic behaviour and disease manifestation of C. albicans have been at the centre of research for many years, its asymptomatic colonization of mucosal surfaces remains surprisingly understudied. In this Review, we discuss the interplay of the fungus, the host and the microbiome on the dualism of commensal and pathogenic life of C. albicans, and how commensal growth is controlled and permitted. We explore hypotheses that could explain how the mucosal environment shapes C. albicans adaptations to its commensal lifestyle, while still maintaining or even increasing its pathogenic potential.

Gut Microbiota in Heart Failure-The Role of Inflammation

Heart failure (HF) has become an immense health concern affecting almost 1-2% of the population globally. It is a complex syndrome characterized by activation of the sympathetic nervous system and the Renin-Angiotensin-Aldosterone (RAAS) axis as well as endothelial dysfunction, oxidative stress, and inflammation. The recent literature points towards the interaction between the intestinal flora and the heart, also called the gut-heart axis. The human gastrointestinal tract is naturally inhabited by various microbes, which are distinct for each patient, regulating the functions of many organs. Alterations of the gut microbiome, a process called dysbiosis, may result in systemic diseases and have been associated with heart failure through inflammatory and autoimmune mechanisms. The disorder of intestinal permeability favors the translocation of microbes and many metabolites capable of inducing inflammation, thus further contributing to the deterioration of normal cardiac function. Besides diet modifications and exercise training, many studies have revealed possible gut microbiota targeted treatments for managing heart failure. The aim of this review is to demonstrate the impact of the inflammatory environment induced by the gut microbiome and its metabolites on heart failure and the elucidation of these novel therapeutic approaches.

Opportunities in exploring chemical biology tools for better strategies against Candida albicans

The growing global prevalence of drug-resistant fungal infections and the scarcity of effective clinical antifungal drugs necessitate an urgent need for new treatments and strategies. In the quest for novel antifungal and anti-virulence compounds and alternative drug targets in fungi, we recognize the significant value of chemical biology tools in guiding these endeavors. Focusing on Candida albicans, the major fungal pathogen in humans, this review explores recent antifungal research efforts that utilize chemical biology tools-such as chemical probes and toolkits-that offer valuable biological insights into the cellular processes of C. albicans. In addition, we discuss the wealth of compounds in the host gut microbiota that naturally influence C. albicans invasive growth in the gut habitat, presenting promising yet underexplored opportunities for developing novel antifungal and anti-virulence strategies. Chemical biology tools are uniquely positioned to unlock the potential of gut microbiota-derived molecules and metabolites in combating C. albicans infections.

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.

Fatty acid composition in the vaginal tract of cis-gender women: canary in coal mines for reproductive health?

The vaginal tract of cis-gender women of reproductive age is inhabited by communities of bacteria generally dominated by one of four Lactobacillus species. These bacteria are important for the reproductive health of women and favor better outcomes, including fertility, pregnancy leading to term and protection against infections. Past studies have focused on the role of carbohydrates in the balance of vaginal communities, and the role of fatty acids has been underestimated. However, small- to long-chain fatty acids present few properties that, in combination with sugar metabolism, affect the outcomes of the health or disease within the vaginal communities. Herein, we explore the origins of fatty acids in the vaginal tract as well as their roles in the bacterial life cycle in this environment. We also detail the putative impact of vaginal FAs on S. aureus, one of the etiologic agents of aerobic vaginitis. Finally, we discuss their potential for prevention or therapy in women of reproductive age.

Jianwei Xiaoshi oral liquid attenuates high-calorie diet-induced dyspepsia in immature rats via regulating the pancreatic secretion pathway and maintaining the homeostasis of intestinal microbiota

BACKGROUND

Jianwei Xiaoshi oral liquid (JWXS), a classical traditional prescription comprising various edible medicinal plants, has demonstrated significant efficacy in treating paediatric indigestion. It originates from Jianpi Pill, which is developed in the Ming Dynasty and nourishes the spleen and regulates gastrointestinal function. However, the specific molecular mechanisms involved remain unclear.

METHODS

To elucidate the material base of JWXS and its underlying mechanism in treating dyspepsia, the UHPLC-Q-Orbitrap HRMS method and network pharmacology were utilized. This was followed by pharmacological experiments, transcriptomics analyses and gut microbiota studies to further investigate the effects of JWXS on dyspepsia.

RESULTS

A total of 105 compounds, mainly flavonoids, alkaloids, organic acids and cyclic peptides, were identified. According to the five principles of generic drug properties, 43 candidate compounds were screened out. Their efficacy was verified through gastric emptying and intestinal propulsion experiments. Transcriptomic analysis revealed that JWXS primarily alleviated dyspepsia symptoms by regulating the secretion of 8 key proteins in the pancreatic secretion pathway. The differences in the gut microbiota, as identified through 16S rRNA and ITS2 sequencing, were subsequently more pronounced than those observed in the bacterial microbiota of the model group. In total, 15 differential bacteria and 16 differential fungi were identified. Targeted metabolomics analysis of SCFAs revealed a significant decrease in valeric acid (VA), acetic acid (AA), and isovaleric acid (IVA) levels in the model group, which were restored to the corresponding levels after the administration of JWXS. Correlation analysis revealed that VA, AA, and IVA were positively correlated with Lactobacillus and Bacteroides, and negatively correlated with Aspergillus and Candida. This further suggested that JWXS might alleviate symptoms of indigestion by regulating the composition of the microbiota, increasing the variety and quantity of beneficial bacteria, reducing fungal contamination, and further increasing the levels of SCFAs in the body.

CONCLUSION

JWXS improved functional dyspepsia in immature rats via a mechanism involving the regulation of the secretion of 8 key proteins in the pancreatic secretion pathway and the amelioration of flora disorders.

Advances in the research of intestinal fungi in Crohn's disease

This article reviews of the original research published by Wu et al in the World Journal of Gastroenterology, delving into the pivotal role of the gut microbiota in the pathogenesis of Crohn's disease (CD). Insights were gained from fecal microbiota transplantation (FMT) in mouse models, revealing the intricate interplay between the gut microbiota, mesenteric adipose tissue (MAT), and creeping fat. The study uncovered the characteristics of inflammation and fibrosis in the MAT and intestinal tissues of patients with CD; moreover, through the FMT mouse model, it observed the impact of samples from healthy patients and those with CD on symptoms. The pathogenesis of CD is complex, and its etiology remains unclear; however, it is widely believed that gut microbiota dysbiosis plays a significant role. Recently, with the development and application of next-generation sequencing technology, research on the role of fungi in the pathogenesis and chronicity of CD has deepened. This editorial serves as a supplement to the research by Wu et al who discussed advances related to the study of fungi in CD.

The signatures and crosstalk of gut microbiome, mycobiome, and metabolites in decompensated cirrhotic patients

BACKGROUND

Numerous studies have confirmed that gut microbiota plays a crucial role in the progression of cirrhosis. However, the contribution of gut fungi in cirrhosis is often overlooked due to the relatively low abundance.

METHODS

We employed 16S ribosomal RNA sequencing, internal transcribed spacer sequencing, and untargeted metabolomics techniques to investigate the composition and interaction of gut bacteria, fungi, and metabolites in cirrhotic patients.

RESULTS

Cirrhotic patients exhibited significant differences in the diversity and composition of gut microbiota and their metabolites in cirrhotic patients compared to healthy individuals. Increase in pathogenic microbial genera and a decrease in beneficial microbial genera including bacteria and fungi were observed. Various clinical indexes were closely connected with these increased metabolites, bacteria, fungi. Additionally, endoscopic treatment was found to impact the gut microbiota and metabolites in cirrhotic patients, although it did not significantly alter the gut ecology. Finally, we constructed a cirrhosis diagnostic model based on different features (bacteria, fungi, metabolites, clinical indexes) with an AUC of 0.938.

CONCLUSION

Our findings revealed the characteristics of gut microbial composition and their intricate internal crosstalk in cirrhotic patients, providing cutting-edge explorations of potential roles of gut microbes in cirrhosis.

Gut-Derived Short-Chain Fatty Acids and Macrophage Modulation: Exploring Therapeutic Potentials in Pulmonary Fungal Infections

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, modulate immune cell functions, particularly macrophages. This review explores the potential therapeutic applications of SCFAs in pulmonary fungal infections, a critical concern due to their high mortality rates and antifungal resistance. SCFAs enhance macrophage functions by promoting phagosome-lysosome fusion, increasing reactive oxygen species production, and balancing cytokine responses. Pulmonary fungal infections, caused by pathogens like Aspergillus fumigatus, are prevalent in immunocompromised patients, including those with diabetes, chronic obstructive pulmonary disease, and those on high-dose corticosteroids. SCFAs have shown promise in improving macrophage function in these contexts. However, the application of SCFAs must be balanced against potential side effects, including gut microbiota disruption and metabolic disorders. Further research is needed to optimize SCFA therapy for managing pulmonary fungal infections.