Key determinants of success in fecal microbiota transplantation: From microbiome to clinic

Gut microbial metabolites in lung cancer development and immunotherapy: Novel insights into gut-lung axis

Metabolic derivatives of numerous microorganisms inhabiting the human gut can participate in regulating physiological activities and immune status of the lungs through the gut-lung axis. The current well-established microbial metabolites include short-chain fatty acids (SCFAs), tryptophan and its derivatives, polyamines (PAs), secondary bile acids (SBAs), etc. As the study continues to deepen, the critical function of microbial metabolites in the occurrence and treatment of lung cancer has gradually been revealed. Microbial derivates can enter the circulation system to modulate the immune microenvironment of lung cancer. Mechanistically, oncometabolites damage host DNA and promote the occurrence of lung cancer, while tumor-suppresive metabolites directly affect the immune system to combat the malignant properties of cancer cells and even show considerable application potential in improving the efficacy of lung cancer immunotherapy. Considering the crosstalk along the gut-lung axis, in-depth exploration of microbial metabolites in patients' feces or serum will provide novel guidance for lung cancer diagnosis and treatment selection strategies. In addition, targeted therapeutics on microbial metabolites are expected to overcome the bottleneck of lung cancer immunotherapy and alleviate adverse reactions, including fecal microbiota transplantation, microecological preparations, metabolite synthesis and drugs targeting metabolic pathways. In summary, this review provides novel insights and explanations on the intricate interplay between gut microbial metabolites and lung cancer development, and immunotherapy through the lens of the gut-lung axis, which further confirms the possible translational potential of the microbiome metabolome in lung cancer treatment.

Fecal virome transplantation: A promising strategy for the treatment of metabolic diseases

Metabolic diseases are a group of disorders caused by metabolic abnormalities, including obesity, diabetes, non-alcoholic fatty liver disease, and more. Increasing research indicates that, beyond inherent metabolic irregularities, the onset and progression of metabolic diseases are closely linked to alterations in the gut microbiota, particularly gut bacteria. Additionally, fecal microbiota transplantation (FMT) has demonstrated effectiveness in clinically treating metabolic diseases, notably diabetes. Recent attention has also focused on the role of gut viruses in disease onset. This review first introduces the characteristics and influencing factors of gut viruses, then summarizes their potential mechanisms in disease development, highlighting their impact on gut bacteria and regulation of host immunity. We also compare FMT, fecal filtrate transplantation (FFT), washed microbiota transplantation (WMT), and fecal virome transplantation (FVT). Finally, we review the current understanding of gut viruses in metabolic diseases and the application of FVT in treating these conditions. In conclusion, FVT may provide a novel and promising treatment approach for metabolic diseases, warranting further validation through basic and clinical research.

Gut microbial metabolites in cancer therapy

The gut microbiota plays a crucial role in maintaining homeostasis and promoting health. A growing number of studies have indicated that gut microbiota can affect cancer development, prognosis, and treatment through their metabolites. By remodeling the tumor microenvironment and regulating tumor immunity, gut microbial metabolites significantly influence the efficacy of anticancer therapies, including chemo-, radio-, and immunotherapy. Several novel therapies that target gut microbial metabolites have shown great promise in cancer models. In this review, we summarize the current research status of gut microbial metabolites in cancer, aiming to provide new directions for future tumor therapy.

Fecal microbiota transplantation alters gut phage communities in a clinical trial for obesity

BACKGROUND

Fecal microbiota transplantation (FMT) is a therapeutic intervention used to treat diseases associated with the gut microbiome. In the human gut microbiome, phages have been implicated in influencing human health, with successful engraftment of donor phages correlated with FMT treatment efficacy. The impact that gastrointestinal phages exert on human health has primarily been connected to their ability to modulate the bacterial communities in the gut. Nonetheless, how FMT affects recipients' phage populations, and in turn, how this influences the gut environment, is not yet fully understood. In this study, we investigated the effects of FMT on the phageome composition of participants within the Gut Bugs Trial (GBT), a double-blind, randomized, placebo-controlled trial that investigated the efficacy of FMT in treating obesity and comorbidities in adolescents. Stool samples collected from donors at the time of treatment and recipients at four time points (i.e., baseline and 6 weeks, 12 weeks, and 26 weeks post-intervention), underwent shotgun metagenomic sequencing. Phage sequences were identified and characterized in silico to examine evidence of phage engraftment and to assess the extent of FMT-induced alterations in the recipients' phageome composition.

RESULTS

Donor phages engrafted stably in recipients following FMT, composing a significant proportion of their phageome for the entire course of the study (33.8 ± 1.2% in females and 33.9 ± 3.7% in males). Phage engraftment varied between donors and donor engraftment efficacy was positively correlated with their phageome alpha diversity. FMT caused a shift in recipients' phageome toward the donors' composition and increased phageome alpha diversity and variability over time.

CONCLUSIONS

FMT significantly altered recipients' phage and, overall, microbial populations. The increase in microbial diversity and variability is consistent with a shift in microbial population dynamics. This proposes that phages play a critical role in modulating the gut environment and suggests novel approaches to understanding the efficacy of FMT in altering the recipient's microbiome.

TRIAL REGISTRATION

The Gut Bugs Trial was registered with the Australian New Zealand Clinical Trials Registry (ACTR N12615001351505). Trial protocol: the trial protocol is available at https://bmjopen.bmj.com/content/9/4/e026174 . Video Abstract.

Integrating functional metagenomics to decipher microbiome-immune interactions

Microbial metabolites can be viewed as the cytokines of the microbiome, transmitting information about the microbial and metabolic environment of the gut to orchestrate and modulate local and systemic immune responses. Still, many immunology studies focus solely on the taxonomy and community structure of the gut microbiota rather than its functions. Early sequencing-based microbiota profiling approaches relied on PCR amplification of small regions of bacterial and fungal genomes to facilitate identification of the microbes present. However, recent microbiome analysis methods, particularly shotgun metagenomic sequencing, now enable culture-independent profiling of microbiome functions and metabolites in addition to taxonomic characterization. In this review, we showcase recent advances in functional metagenomics methods and applications and discuss the current limitations and potential avenues for future development. Importantly, we highlight a few examples of key areas of opportunity in immunology research where integrating functional metagenomic analyses of the microbiome can substantially enhance a mechanistic understanding of microbiome-immune interactions and their contributions to health and disease states.

Current and future microbiome-based therapies in inflammatory bowel disease

PURPOSE OF REVIEW

The role of the microbiome and dysbiosis is increasingly recognized in the pathogenesis of inflammatory bowel disease (IBD). Intestinal microbiota transplant (IMT), previously termed fecal microbiota transplant has demonstrated efficacy in restoring a healthy microbiome and promoting gut health in recurrent Clostridioides difficile infection. Several randomized trials (RCTs) highlighted IMT's potential in treating ulcerative colitis, while smaller studies reported on its application in managing Crohn's disease and pouchitis.

RECENT FINDINGS

This review delves into the current understanding of dysbiosis in IBD, highlighting the distinctions in the microbiota of patients with IBD compared to healthy controls. It explores the mechanisms by which IMT can restore a healthy microbiome and provides a focused analysis of recent RCTs using IMT for inducing and maintaining remission in IBD. Lastly, we discuss the current knowledge gaps that limit its widespread use.

SUMMARY

The body of evidence supporting the use of IMT in IBD is growing. The lack of a standardized protocol impedes its application beyond clinical trials. Further research is needed to identify patient profile and disease phenotypes that benefit from IMT, to delineate key donor characteristics, optimize the delivery route, dosage, and frequency.

Harnessing CD8+ T cell dynamics in hepatitis B virus-associated liver diseases: Insights, therapies and future directions

Hepatitis B virus (HBV) infection playsa significant role in the etiology and progression of liver-relatedpathologies, encompassing chronic hepatitis, fibrosis, cirrhosis, and eventual hepatocellularcarcinoma (HCC). Notably, HBV infection stands as the primary etiologicalfactor driving the development of HCC. Given the significant contribution ofHBV infection to liver diseases, a comprehensive understanding of immunedynamics in the liver microenvironment, spanning chronic HBV infection,fibrosis, cirrhosis, and HCC, is essential. In this review, we focused on thefunctional alterations of CD8+ T cells within the pathogenic livermicroenvironment from HBV infection to HCC. We thoroughly reviewed the roles ofhypoxia, acidic pH, metabolic reprogramming, amino acid deficiency, inhibitory checkpointmolecules, immunosuppressive cytokines, and the gut-liver communication in shapingthe dysfunction of CD8+ T cells in the liver microenvironment. Thesefactors significantly impact the clinical prognosis. Furthermore, we comprehensivelyreviewed CD8+ T cell-based therapy strategies for liver diseases,encompassing HBV infection, fibrosis, cirrhosis, and HCC. Strategies includeimmune checkpoint blockades, metabolic T-cell targeting therapy, therapeuticT-cell vaccination, and adoptive transfer of genetically engineered CD8+ T cells, along with the combined usage of programmed cell death protein-1/programmeddeath ligand-1 (PD-1/PD-L1) inhibitors with mitochondria-targeted antioxidants.Given that targeting CD8+ T cells at various stages of hepatitis Bvirus-induced hepatocellular carcinoma (HBV + HCC) shows promise, we reviewedthe ongoing need for research to elucidate the complex interplay between CD8+ T cells and the liver microenvironment in the progression of HBV infection toHCC. We also discussed personalized treatment regimens, combining therapeuticstrategies and harnessing gut microbiota modulation, which holds potential forenhanced clinical benefits. In conclusion, this review delves into the immunedynamics of CD8+ T cells, microenvironment changes, and therapeuticstrategies within the liver during chronic HBV infection, HCC progression, andrelated liver diseases.

Current landscape of fecal microbiota transplantation in treating depression

Depression, projected to be the predominant contributor to the global disease burden, is a complex condition with diverse symptoms including mood disturbances and cognitive impairments. Traditional treatments such as medication and psychotherapy often fall short, prompting the pursuit of alternative interventions. Recent research has highlighted the significant role of gut microbiota in mental health, influencing emotional and neural regulation. Fecal microbiota transplantation (FMT), the infusion of fecal matter from a healthy donor into the gut of a patient, emerges as a promising strategy to ameliorate depressive symptoms by restoring gut microbial balance. The microbial-gut-brain (MGB) axis represents a critical pathway through which to potentially rectify dysbiosis and modulate neuropsychiatric outcomes. Preclinical studies reveal that FMT can enhance neurochemicals and reduce inflammatory markers, thereby alleviating depressive behaviors. Moreover, FMT has shown promise in clinical settings, improving gastrointestinal symptoms and overall quality of life in patients with depression. The review highlights the role of the gut-brain axis in depression and the need for further research to validate the long-term safety and efficacy of FMT, identify specific therapeutic microbial strains, and develop targeted microbial modulation strategies. Advancing our understanding of FMT could revolutionize depression treatment, shifting the paradigm toward microbiome-targeting therapies.

Gut-Liver-Pancreas Axis Crosstalk in Health and Disease: From the Role of Microbial Metabolites to Innovative Microbiota Manipulating Strategies

The functions of the gut are closely related to those of many other organs in the human body. Indeed, the gut microbiota (GM) metabolize several nutrients and compounds that, once released in the bloodstream, can reach distant organs, thus influencing the metabolic and inflammatory tone of the host. The main microbiota-derived metabolites responsible for the modulation of endocrine responses are short-chain fatty acids (SCFAs), bile acids and glucagon-like peptide 1 (GLP-1). These molecules can (i) regulate the pancreatic hormones (insulin and glucagon), (ii) increase glycogen synthesis in the liver, and (iii) boost energy expenditure, especially in skeletal muscles and brown adipose tissue. In other words, they are critical in maintaining glucose and lipid homeostasis. In GM dysbiosis, the imbalance of microbiota-related products can affect the proper endocrine and metabolic functions, including those related to the gut-liver-pancreas axis (GLPA). In addition, the dysbiosis can contribute to the onset of some diseases such as non-alcoholic steatohepatitis (NASH)/non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC), and type 2 diabetes (T2D). In this review, we explored the roles of the gut microbiota-derived metabolites and their involvement in onset and progression of these diseases. In addition, we detailed the main microbiota-modulating strategies that could improve the diseases' development by restoring the healthy balance of the GLPA.

Fecal microbiota transplantation: current challenges and future landscapes

SUMMARYGiven the importance of gut microbial homeostasis in maintaining health, there has been considerable interest in developing innovative therapeutic strategies for restoring gut microbiota. One such approach, fecal microbiota transplantation (FMT), is the main "whole gut microbiome replacement" strategy and has been integrated into clinical practice guidelines for treating recurrent Clostridioides difficile infection (rCDI). Furthermore, the potential application of FMT in other indications such as inflammatory bowel disease (IBD), metabolic syndrome, and solid tumor malignancies is an area of intense interest and active research. However, the complex and variable nature of FMT makes it challenging to address its precise functionality and to assess clinical efficacy and safety in different disease contexts. In this review, we outline clinical applications, efficacy, durability, and safety of FMT and provide a comprehensive assessment of its procedural and administration aspects. The clinical applications of FMT in children and cancer immunotherapy are also described. We focus on data from human studies in IBD in contrast with rCDI to delineate the putative mechanisms of this treatment in IBD as a model, including colonization resistance and functional restoration through bacterial engraftment, modulating effects of virome/phageome, gut metabolome and host interactions, and immunoregulatory actions of FMT. Furthermore, we comprehensively review omics technologies, metagenomic approaches, and bioinformatics pipelines to characterize complex microbial communities and discuss their limitations. FMT regulatory challenges, ethical considerations, and pharmacomicrobiomics are also highlighted to shed light on future development of tailored microbiome-based therapeutics.

The use of faecal microbiota transplant as treatment for recurrent or refractory Clostridioides difficile infection and other potential indications: second edition of joint British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS) guidelines

The first British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS)-endorsed faecal microbiota transplant (FMT) guidelines were published in 2018. Over the past 5 years, there has been considerable growth in the evidence base (including publication of outcomes from large national FMT registries), necessitating an updated critical review of the literature and a second edition of the BSG/HIS FMT guidelines. These have been produced in accordance with National Institute for Health and Care Excellence-accredited methodology, thus have particular relevance for UK-based clinicians, but are intended to be of pertinence internationally. This second edition of the guidelines have been divided into recommendations, good practice points and recommendations against certain practices. With respect to FMT for Clostridioides difficile infection (CDI), key focus areas centred around timing of administration, increasing clinical experience of encapsulated FMT preparations and optimising donor screening. The latter topic is of particular relevance given the COVID-19 pandemic, and cases of patient morbidity and mortality resulting from FMT-related pathogen transmission. The guidelines also considered emergent literature on the use of FMT in non-CDI settings (including both gastrointestinal and non-gastrointestinal indications), reviewing relevant randomised controlled trials. Recommendations are provided regarding special areas (including compassionate FMT use), and considerations regarding the evolving landscape of FMT and microbiome therapeutics.

Gut microbes improve prognosis of Klebsiella pneumoniae pulmonary infection through the lung-gut axis

Background

The gut microbiota plays a vital role in the development of sepsis and in protecting against pneumonia. Previous studies have demonstrated the existence of the gut-lung axis and the interaction between the gut and the lung, which is related to the prognosis of critically ill patients; however, most of these studies focused on chronic lung diseases and influenza virus infections. The purpose of this study was to investigate the effect of faecal microbiota transplantation (FMT) on Klebsiella pneumoniae-related pulmonary infection via the gut-lung axis and to compare the effects of FMT with those of traditional antibiotics to identify new therapeutic strategies.

Methods

We divided the mice into six groups: the blank control (PBS), pneumonia-derived sepsis (KP), pneumonia-derived sepsis + antibiotic (KP + PIP), pneumonia-derived sepsis + faecal microbiota transplantation(KP + FMT), antibiotic treatment control (KP+PIP+PBS), and pneumonia-derived sepsis+ antibiotic + faecal microbiota transplantation (KP + PIP + FMT) groups to compare the survival of mice, lung injury, inflammation response, airway barrier function and the intestinal flora, metabolites and drug resistance genes in each group.

Results

Alterations in specific intestinal flora can occur in the gut of patients with pneumonia-derived sepsis caused by Klebsiella pneumoniae. Compared with those in the faecal microbiota transplantation group, the antibiotic treatment group had lower levels of proinflammatory factors and higher levels of anti-inflammatory factors but less amelioration of lung pathology and improvement of airway epithelial barrier function. Additionally, the increase in opportunistic pathogens and drug resistance-related genes in the gut of mice was accompanied by decreased production of favourable fatty acids such as acetic acid, propionic acid, butyric acid, decanoic acid, and secondary bile acids such as chenodeoxycholic acid 3-sulfate, isodeoxycholic acid, taurodeoxycholic acid, and 3-dehydrocholic acid; the levels of these metabolites were restored by faecal microbiota transplantation. Faecal microbiota transplantation after antibiotic treatment can gradually ameliorate gut microbiota disorder caused by antibiotic treatment and reduce the number of drug resistance genes induced by antibiotics.

Conclusion

In contrast to direct antibiotic treatment, faecal microbiota transplantation improves the prognosis of mice with pneumonia-derived sepsis caused by Klebsiella pneumoniae by improving the structure of the intestinal flora and increasing the level of beneficial metabolites, fatty acids and secondary bile acids, thereby reducing systemic inflammation, repairing the barrier function of alveolar epithelial cells, and alleviating pathological damage to the lungs. The combination of antibiotics with faecal microbiota transplantation significantly alleviates intestinal microbiota disorder, reduces the selection for drug resistance genes caused by antibiotics, and mitigates lung lesions; these effects are superior to those following antibiotic monotherapy.

Pleurotus eryngii polysaccharides alleviate aflatoxin B1-induced liver inflammation in ducks involving in remodeling gut microbiota and regulating SCFAs transport via the gut-liver axis

Aflatoxin B1 (AFB1) is one of the most widespread contaminants in agricultural commodities. Pleurotus eryngii (PE) is widely used as a feed additive for its anti-inflammatory properties, and its major active substance is believed to be polysaccharides. This study aims to explore the underlying mechanism of dietary PE polysaccharides alleviating AFB1-induced toxicity in ducks. The major monosaccharide components of PE polysaccharides were identified as glucose, mannose, galactose, glucuronic acid, and fucose. The results showed that dietary PE polysaccharides could alleviate liver inflammation, alleviate intestinal barrier dysfunction, and change the imbalanced gut microbiota induced by AFB1 in ducks. However, PE polysaccharides failed to exert protective roles on the liver and intestine injury induced by AFB1 in antibiotic-treated ducks. The PE + AFB1-originated microbiota showed a positive effect on intestinal barrier and inflammation, the SCFAs transport via the gut-liver axis, and liver inflammation compared with the AFB1-originated microbiota in ducks. These findings provided a possible mechanism that PE polysaccharides alleviated AFB1-induced liver inflammation in ducks by remodeling gut microbiota, regulating microbiota-derived SCFAs transport via the gut-liver axis, and inhibiting inflammatory gene expressions in the liver, which may provide new insight for therapeutic methods against AFB1 exposure in animals.

The use of faecal microbiota transplant as treatment for recurrent or refractory Clostridioides difficile infection and other potential indications: second edition of joint British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS) guidelines

The first British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS)-endorsed faecal microbiota transplant (FMT) guidelines were published in 2018. Over the past 5 years, there has been considerable growth in the evidence base (including publication of outcomes from large national FMT registries), necessitating an updated critical review of the literature and a second edition of the BSG/HIS FMT guidelines. These have been produced in accordance with National Institute for Health and Care Excellence-accredited methodology, thus have particular relevance for UK-based clinicians, but are intended to be of pertinence internationally. This second edition of the guidelines have been divided into recommendations, good practice points and recommendations against certain practices. With respect to FMT for Clostridioides difficile infection (CDI), key focus areas centred around timing of administration, increasing clinical experience of encapsulated FMT preparations and optimising donor screening. The latter topic is of particular relevance given the COVID-19 pandemic, and cases of patient morbidity and mortality resulting from FMT-related pathogen transmission. The guidelines also considered emergent literature on the use of FMT in non-CDI settings (including both gastrointestinal and non-gastrointestinal indications), reviewing relevant randomised controlled trials. Recommendations are provided regarding special areas (including compassionate FMT use), and considerations regarding the evolving landscape of FMT and microbiome therapeutics.

Fecal Microbiota Transplantation Repairs Radiation Enteritis Through Modulating the Gut Microbiota-Mediated Tryptophan Metabolism

Radiation enteritis is a common complication of abdominal and pelvic radiotherapy. Several previous studies showed that fecal microbiota transplantation (FMT) could alleviate radiation enteritis. In this study, we investigated the efficacy of FMT in alleviating radiation enteritis and explored the mechanisms by multi-omics approaches. Briefly, C57BL/6J mice were subjected to 9 Gy irradiation to the localized abdominal field, and randomized received FMT from healthy donor mice or saline. H&E staining of harvested small intestine showed FMT decreased epithelial injury. Radiation-induced microbiota dysbiosis, characterized by a decrease in beneficial bacteria Lactobacillaceae and Lachnospiraceae, while these bacteria were restored by FMT. Fecal metabolomics analysis revealed that FMT modulated metabolic dysregulation. Two tryptophan pathway metabolites, indole-3-acetaldehyde and N-Acetyl-5-hydroxytryptamine were decreased after irradiation, whereas these metabolites showed a pronounced recovery in mice receiving FMT. Proteomics analysis of small intestine indicated that radiation enteritis triggered immune-inflammatory responses, which were potentially mitigated by FMT. In 21 patients receiving pelvic radiotherapy for cervical cancer, those who developed enteritis (n = 15) had higher abundance in Lachnospiraceae. Moreover, Indole-3-acetaldehyde was reduced after irradiation. These findings provide insights into the therapeutic effects of FMT in radiation enteritis and highlight Lachnospiraceae and the tryptophan metabolite, Indole-3-acetaldehyde may protect against radiation enteritis.

Human Gut Microbiota for Diagnosis and Treatment of Depression

Nowadays, depressive disorder is spreading rapidly all over the world. Therefore, attention to the studies of the pathogenesis of the disease in order to find novel ways of early diagnosis and treatment is increasing among the scientific and medical communities. Special attention is drawn to a biomarker and therapeutic strategy through the microbiota-gut-brain axis. It is known that the symbiotic interactions between the gut microbes and the host can affect mental health. The review analyzes the mechanisms and ways of action of the gut microbiota on the pathophysiology of depression. The possibility of using knowledge about the taxonomic composition and metabolic profile of the microbiota of patients with depression to select gene compositions (metagenomic signature) as biomarkers of the disease is evaluated. The use of in silico technologies (machine learning) for the diagnosis of depression based on the biomarkers of the gut microbiota is given. Alternative approaches to the treatment of depression are being considered by balancing the microbial composition through dietary modifications and the use of additives, namely probiotics, postbiotics (including vesicles) and prebiotics as psychobiotics, and fecal transplantation. The bacterium Faecalibacterium prausnitzii is under consideration as a promising new-generation probiotic and auxiliary diagnostic biomarker of depression. The analysis conducted in this review may be useful for clinical practice and pharmacology.

Relative dispersion ratios following fecal microbiota transplant elucidate principles governing microbial migration dynamics

Microorganisms frequently migrate from one ecosystem to another. Yet, despite the potential importance of this process in modulating the environment and the microbial ecosystem, our understanding of the fundamental forces that govern microbial dispersion is still lacking. Moreover, while theoretical models and in-vitro experiments have highlighted the contribution of species interactions to community assembly, identifying such interactions in vivo, specifically in communities as complex as the human gut, remains challenging. To address this gap, here we introduce a robust and rigorous computational framework, termed Relative Dispersion Ratio (RDR) analysis, and leverage data from well-characterized fecal microbiota transplant trials, to rigorously pinpoint dependencies between taxa during the colonization of human gastrointestinal tract. Our analysis identifies numerous pairwise dependencies between co-colonizing microbes during migration between gastrointestinal environments. We further demonstrate that identified dependencies agree with previously reported findings from in-vitro experiments and population-wide distribution patterns. Finally, we explore metabolic dependencies between these taxa and characterize the functional properties that facilitate effective dispersion. Collectively, our findings provide insights into the principles and determinants of community dynamics following ecological translocation, informing potential opportunities for precise community design.

The Progression of Microbiome Therapeutics for the Management of Gastrointestinal Diseases and Beyond

There has been an increased ability to investigate the human microbiota through next-generation sequencing and functional assessment. This advancement has rapidly expanded our ability to study and manipulate the gastrointestinal microbiome to mitigate disease. Fecal microbiota transplantation, a therapy that broadly transfers the entire intestinal ecosystem, has been explored as a potential therapeutic in a variety of gastrointestinal, hepatic, and extraintestinal conditions. The field, however, continues to evolve, with a movement toward precision microbiome therapeutics, individualizing care for various disorders. This review will describe the use of fecal microbiota transplantation, microbiota restoration, and precision microbiome therapeutics, focusing on gastrointestinal and hepatic diseases.

Gut microbiota and metabolites as predictors of biologics response in inflammatory bowel disease: A comprehensive systematic review

Nonresponse to biologic agents in patients with inflammatory bowel disease (IBD) poses a significant public health burden, and the prediction of response to biologics offers valuable insights for IBD management. Given the pivotal role of gut microbiota and their endogenous metabolites in IBD, we conducted a systematic review to investigate the potential of fecal microbiota and mucosal microbiota and endogenous metabolomic markers as predictors for biotherapy response in IBD patients. A total of 38 studies were included in the review. Following anti-TNF-α treatment, the bacterial community characteristics of IBD patients exhibited a tendency to resemble those observed in healthy controls, indicating an improved clinical response. The levels of endogenous metabolites butyrate and deoxycholic acid were significantly associated with clinical remission following anti-TNF-α therapy. IBD patients who responded well to vedolizumab treatment had higher levels of specific bacteria that produce butyrate, along with increased levels of metabolites such as butyrate, branched-chain amino acids and acetamide following vedolizumab treatment. Crohn's disease patients who responded positively to ustekinumab treatment showed higher levels of Faecalibacterium and lower levels of Escherichia/Shigella. In conclusion, fecal microbiota and mucosal microbiota as well as their endogenous metabolites could provide a predictive tool for assessing the response of IBD patients to various biological agents and serve as a valuable reference for precise drug selection in clinical IBD patients.

Fine-tuning the gut ecosystem: the current landscape and outlook of artificial microbiome therapeutics

The gut microbiome is acknowledged as a key determinant of human health, and technological progress in the past two decades has enabled the deciphering of its composition and functions and its role in human disorders. Therefore, manipulation of the gut microbiome has emerged as a promising therapeutic option for communicable and non-communicable disorders. Full exploitation of current therapeutic microbiome modulators (including probiotics, prebiotics, and faecal microbiota transplantation) is hindered by several factors, including poor precision, regulatory and safety issues, and the impossibility of providing reproducible and targeted treatments. Artificial microbiota therapeutics (which include a wide range of products, such as microbiota consortia, bacteriophages, bacterial metabolites, and engineered probiotics) have appeared as an evolution of current microbiota modulators, as they promise safe and reproducible effects, with variable levels of precision via different pathways. We describe the landscape of artificial microbiome therapeutics, from those already on the market to those still in the pipeline, and outline the major challenges for positioning these therapeutics in clinical practice.

Comprehensive assessment of HF-rTMS treatment mechanism for post-stroke dysphagia in rats by integration of fecal metabolomics and 16S rRNA sequencing

Background

The mechanism by which high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) improves swallowing function by regulating intestinal flora remains unexplored. We aimed to evaluate this using fecal metabolomics and 16S rRNA sequencing.

Methods

A Post-stroke dysphagia (PSD) rat model was established by middle cerebral artery occlusion. The magnetic stimulation group received HF-rTMS from the 7th day post-operation up to 14th day post-surgery. Swallowing function was assessed using a videofluoroscopic swallowing study (VFSS). Hematoxylin-eosin (H&E) staining was used to assess histopathological changes in the intestinal tissue. Intestinal flora levels were evaluated by sequencing the 16S rRNA V3-V4 region. Metabolite changes within the intestinal flora were evaluated by fecal metabolomics using liquid chromatography-tandem mass spectrometry.

Results

VFSS showed that the bolus area and pharyngeal bolus speed were significantly decreased in PSD rats, while the bolus area increased and pharyngeal transit time decreased after HF-rTMS administration (p < 0.05). In the PSD groups, H&E staining revealed damaged surface epithelial cells and disrupted cryptal glands, whereas HF-rTMS reinforced the integrity of the intestinal epithelial cells. 16S rRNA sequencing indicated that PSD can disturb the intestinal flora and its associated metabolites, whereas HF-rTMS can significantly regulate the composition of the intestinal microflora. Firmicutes and Lactobacillus abundances were lower in the PSD group than in the baseline group at the phylum and genus levels, respectively; however, both increased after HF-rTMS administration. Levels of ceramides (Cer), free fatty acids (FA), phosphatidylethanolamine (PE), triacylglycerol (TAG), and sulfoquinovosyl diacylglycerol were increased in the PSD group. The Cer, FA, and DG levels decreased after HF-rTMS treatment, whereas the TAG levels increased. Peptococcaceae was negatively correlated with Cer, Streptococcus was negatively correlated with DG, and Acutalibacter was positively correlated with FA and Cer. However, these changes were effectively restored by HF-rTMS, resulting in recovery from dysphagia.

Conclusion

These findings suggest a synergistic role for the gut microbiota and fecal metabolites in the development of PSD and the therapeutic mechanisms underlying HF-rTMS.

Advances in fecal microbiota transplantation for the treatment of diabetes mellitus

Diabetes mellitus (DM) refers to a group of chronic diseases with global prevalence, characterized by persistent hyperglycemia resulting from various etiologies. DM can harm various organ systems and lead to acute or chronic complications, which severely endanger human well-being. Traditional treatment mainly involves controlling blood sugar levels through replacement therapy with drugs and insulin; however, some patients still find a satisfactory curative effect difficult to achieve. Extensive research has demonstrated a close correlation between enteric dysbacteriosis and the pathogenesis of various types of DM, paving the way for novel therapeutic approaches targeting the gut microbiota to manage DM. Fecal microbiota transplantation (FMT), a method for re-establishing the intestinal microbiome balance, offers new possibilities for treating diabetes. This article provides a comprehensive review of the correlation between DM and the gut microbiota, as well as the current advancements in FMT treatment for DM, using FMT as an illustrative example. This study aims to offer novel perspectives and establish a theoretical foundation for the clinical diagnosis and management of DM.

Update on microbiota-derived therapies for recurrent Clostridioides difficile infections

BACKGROUND

Faecal microbiota transplantation (FMT) is the standard treatment for patients with multiple recurrent Clostridioides difficile infection (rCDI). Recently, new commercially developed human microbiota-derived medicinal products have been evaluated and Food and Drug Administration-approved with considerable differences in terms of composition, administration, and targeted populations.

OBJECTIVES

To review available data on the different microbiota-derived treatments at the stage of advanced clinical evaluation and research in rCDI in comparison with FMT.

SOURCES

Phase II or III trials evaluating a microbiota-derived medicinal product to prevent rCDI.

CONTENT

Two commercial microbiota-derived medicinal products are approved by the Food and Drug Administration: Rebyota (RBX2660 Ferring Pharmaceuticals, marketed in the United States) and VOWST (SER-109 -Seres Therapeutics, marketed in the United States), whereas VE303 (Vedanta Biosciences Inc) will be studied in phase III trial. RBX2660 and SER-109 are based on the processing of stools from healthy donors, whereas VE303 consists of a defined bacterial consortium originating from human stools and produced from clonal cell banks. All have proven efficacy to prevent rCDI compared with placebo in patients considered at high risk of recurrence. However, the heterogeneity of the inclusion criteria, and the time between each episode and CDI diagnostics makes direct comparison between trials difficult. The differences regarding the risk of recurrence between the treatment and placebo arms were lower than previously described for FMT (FMT: Δ = 50.5%; RBX2660-phase III: Δ = 13.1%; SER-109-phase III: Δ = 28%; high-dose VE303-phase-II: Δ = 31.7%). All treatments presented a good overall safety profile with mainly mild gastrointestinal symptoms.

IMPLICATIONS

Stool-derived products and bacterial consortia need to be clearly distinguished in terms of product characterization and their associated risks with specific long-term post-marketing evaluation similar to registries used for FMT. Their place in the therapeutic strategy for patients with rCDI requires further studies to determine the most appropriate patient population and administration route to prevent rCDI.

Microbiome and lung cancer: carcinogenic mechanisms, early cancer diagnosis, and promising microbial therapies

Microbiomes in the lung, gut, and oral cavity are correlated with lung cancer initiation and progression. While correlations have been preliminarily established in earlier studies, delving into microbe-mediated carcinogenic mechanisms will extend our understanding from correlation to causation. Building upon the causative relationships between microbiome and lung cancer, a novel concept of microbial biomarkers has emerged, mainly encompassing cancer-specific bacteria and circulating microbiome DNA. They might function as noninvasive liquid biopsy techniques for lung cancer early detection. Furthermore, potential microbial therapies have displayed initial efficacy in lung cancer treatment, providing multiple avenues for therapeutic intervention. Herein, we will discuss the molecular mechanisms and signaling pathways through which microbes influence lung cancer initiation and development. Additionally, we will summarize recent findings on microbial biomarkers as a member of tumor liquid biopsy techniques and provide an overview of the latest advances in various microbe-assisted/mediated therapeutic approaches for lung cancer.

Microbiome One Health model for a healthy ecosystem

The attention on microbiome research and its translation to application deployment is escalating along with diffused hype. There is real excitement in this new science, leveraging the growing potential of advances in molecular biology and sequencing techniques. Yet, despite the substantial efforts provided by the scientific communities, the true significance of research achievements requires coordinated and constructive actions across interdisciplinary fields. Individual researchers, universities, small and large companies, venture capitalists, and governments play a fundamental role in fostering collaboration and promoting knowledge that will benefit each other and sustain global prosperity. Making meaningful connections across different fields and getting a new perspective on how technological developments interrelate are the main drivers for creativity and progress. To help the broader innovation community focus on potentially new cross-sectorial developments, the One Health-microbiome-centric approach, defined here as "Microbiome One Health " , is considered as the efficient, holistic approach to product and service exploitations meant to preserve human well-being within a healthy ecosystem. The model opposes the biomedical system and generalizes the "One World-One Health ™" concept. The focus will be given to Nutrition as a driver of health and the food system for its commercial exploitation microbiome-centric, specifically at the interface of human/animal/agricultural. Remarkably, at the interface of humans/animals, the interaction with pets, specifically dogs, has been recognized as a driving force of novel microbiome exploitation.

Bacterial microbiome changes after fecal transplantation for recurrent Clostridioides difficile infection in the Brazilian center

Clostridioides difficile infection (CDI) poses a significant global health threat owing to its substantial morbidity and associated healthcare costs. A key challenge in controlling CDI is the risk of multiple recurrences, which can affect up to 30% of patients. In such instances, fecal microbiota transplantation (FMT) is increasingly recognized as the optimal treatment. However, few related studies have been conducted in developing countries, and the microbiota composition of Brazilian patients and its dynamic modification post-FMT remain largely unexplored. This study aimed to evaluate the changes in the bacterial gut microbiome in Brazilian patients with recurrent CDI post-FMT. Ten patients underwent FMT, and the primary and overall CDI resolution rates were 80% and 90% after the first and second FMT, respectively. FMT was associated with an early increase in Shannon's diversity, evident as soon as 1 week post-FMT and persisting for at least 25 days post-treatment. Post-treatment, the abundance of Firmicutes increased and that of Proteobacteria decreased. Specifically, the abundance of the genera Ruminococcus, Faecalibacterium, Lachnospira, and Roseburia of the Firmicutes phylum was significantly higher 1 week post-transplantation, with Ruminococcus and Faecalibacterium remaining enriched 25 days post-transplantation. This study is the first of its kind in Brazil to evaluate the microbiota of a donor and patients undergoing FMT. Our findings suggest that FMT can induce remarkable changes in the gut microbiota, characterized by an early and sustained increase in diversity lasting at least 25 days. FMT also promotes enrichment of genera such as Ruminococcus spp., Faecalibacterium spp., and Roseburia spp., essential for therapeutic success.

AGA Clinical Practice Guideline on Fecal Microbiota-Based Therapies for Select Gastrointestinal Diseases

BACKGROUND & AIMS

Fecal microbiota-based therapies include conventional fecal microbiota transplant and US Food and Drug Administration-approved therapies, fecal microbiota live-jslm and fecal microbiota spores live-brpk. The American Gastroenterological Association (AGA) developed this guideline to provide recommendations on the use of fecal microbiota-based therapies in adults with recurrent Clostridioides difficile infection; severe to fulminant C difficile infection; inflammatory bowel diseases, including pouchitis; and irritable bowel syndrome.

METHODS

The guideline was developed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) framework to prioritize clinical questions, identify patient-centered outcomes, and conduct an evidence synthesis. The guideline panel used the Evidence-to-Decision framework to develop recommendations for the use of fecal microbiota-based therapies in the specified gastrointestinal conditions and provided implementation considerations for clinical practice.

RESULTS

The guideline panel made 7 recommendations. In immunocompetent adults with recurrent C difficile infection, the AGA suggests select use of fecal microbiota-based therapies on completion of standard of care antibiotics to prevent recurrence. In mildly or moderately immunocompromised adults with recurrent C difficile infection, the AGA suggests select use of conventional fecal microbiota transplant. In severely immunocompromised adults, the AGA suggests against the use of any fecal microbiota-based therapies to prevent recurrent C difficile. In adults hospitalized with severe or fulminant C difficile not responding to standard of care antibiotics, the AGA suggests select use of conventional fecal microbiota transplant. The AGA suggests against the use of conventional fecal microbiota transplant as treatment for inflammatory bowel diseases or irritable bowel syndrome, except in the context of clinical trials.

CONCLUSIONS

Fecal microbiota-based therapies are effective therapy to prevent recurrent C difficile in select patients. Conventional fecal microbiota transplant is an adjuvant treatment for select adults hospitalized with severe or fulminant C difficile infection not responding to standard of care antibiotics. Fecal microbiota transplant cannot yet be recommended in other gastrointestinal conditions.

Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases

The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.

Gut microbiota, microbiota-derived metabolites, and graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is one of the most effective treatment strategies for leukemia, lymphoma, and other hematologic malignancies. However, graft-versus-host disease (GVHD) can significantly reduce the survival rate and quality of life of patients after transplantation, and is therefore the greatest obstacle to transplantation. The recent development of new technologies, including high-throughput sequencing, metabolomics, and others, has facilitated great progress in understanding the complex interactions between gut microbiota, microbiota-derived metabolites, and the host. Of these interactions, the relationship between gut microbiota, microbial-associated metabolites, and GVHD has been most intensively researched. Studies have shown that GVHD patients often suffer from gut microbiota dysbiosis, which mainly manifests as decreased microbial diversity and changes in microbial composition and microbiota-derived metabolites, both of which are significant predictors of poor prognosis in GVHD patients. Therefore, the purpose of this review is to summarize what is known regarding changes in gut microbiota and microbiota-derived metabolites in GVHD, their relationship to GVHD prognosis, and corresponding clinical strategies designed to prevent microbial dysregulation and facilitate treatment of GVHD.

Gut microbiota and dietary intervention: affecting immunotherapy efficacy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) accounts for 80-85% of all lung cancers. In recent years, treatment with immune checkpoint inhibitors (ICIs) has gradually improved the survival rate of patients with NSCLC, especially those in the advanced stages. ICIs can block the tolerance pathways that are overexpressed by tumor cells and maintain the protective activity of immune system components against cancer cells. Emerging clinical evidence suggests that gut microbiota may modulate responses to ICIs treatment, possibly holding a key role in tumor immune surveillance and the efficacy of ICIs. Studies have also shown that diet can influence the abundance of gut microbiota in humans, therefore, dietary interventions and the adjustment of the gut microbiota is a novel and promising treatment strategy for adjunctive cancer therapy. This review comprehensively summarizes the effects of gut microbiota, antibiotics (ATBs), and dietary intervention on the efficacy of immunotherapy in NSCLC, with the aim of informing the development of novel strategies in NSCLC immunotherapy.

Melanoma and microbiota: Current understanding and future directions

Over the last decade, the composition of the gut microbiota has been found to correlate with the outcomes of cancer patients treated with immunotherapy. Accumulating evidence points to the various mechanisms by which intestinal bacteria act on distal tumors and how to harness this complex ecosystem to circumvent primary resistance to immune checkpoint inhibitors. Here, we review the state of the microbiota field in the context of melanoma, the recent breakthroughs in defining microbial modes of action, and how to modulate the microbiota to enhance response to cancer immunotherapy. The host-microbe interaction may be deciphered by the use of "omics" technologies, and will guide patient stratification and the development of microbiota-centered interventions. Efforts needed to advance the field and current gaps of knowledge are also discussed.

The practice of fecal microbiota transplantation in inflammatory bowel disease

Current evidence posits a central role for gut microbiota and the metabolome in the pathogenesis and progression of inflammatory bowel disease (IBD). Fecal microbiota transplantation (FMT) has been established as a means to manipulate this microbiome safely and sustainably. Several aspects of the technical improvement including pretreatment with antibiotics, use of frozen stool samples as well as short donor-to-recipient time are proposed to improve its response rates. Its efficacy in ulcerative colitis has been proven in clinical trials while data is emerging for Crohn's disease. This review describes briefly the biology behind FMT, the available evidence for its use in IBD, and the host, recipient and procedural factors which determine the clinical outcomes.

Ecological insights into hematopoiesis regulation: unraveling the influence of gut microbiota

The gut microbiota constitutes a vast ecological system within the human body, forming a mutually interdependent entity with the host. In recent years, advancements in molecular biology technologies have provided a clearer understanding of the role of the gut microbiota. They not only influence the local immune status and metabolic functions of the host's intestinal tract but also impact the functional transformation of hematopoietic stem cells (HSCs) through the gut-blood axis. In this review, we will discuss the role of the gut microbiota in influencing hematopoiesis. We analyze the interactions between HSCs and other cellular components, with a particular emphasis on the direct functional regulation of HSCs by the gut microbiota and their indirect influence through cellular components in the bone marrow microenvironment. Additionally, we propose potential control targets for signaling pathways triggered by the gut microbiota to regulate hematopoietic function, filling crucial knowledge gaps in the development of this research field.

Washed microbiota transplantation promotes homing of group 3 innate lymphoid cells to the liver via the CXCL16/CXCR6 axis: a potential treatment for metabolic-associated fatty liver disease

Despite the observed decrease in liver fat associated with metabolic-associated fatty liver disease (MAFLD) in mice following fecal microbiota transplantation, the clinical effects and underlying mechanisms of washed microbiota transplantation (WMT), a refined method of fecal microbiota transplantation, for the treatment of MAFLD remain unclear. In this study, both patients and mice with MAFLD exhibit an altered gut microbiota composition. WMT increases the levels of beneficial bacteria, decreases the abundance of pathogenic bacteria, and reduces hepatic steatosis in MAFLD-affected patients and mice. Downregulation of the liver-homing chemokine receptor CXCR6 on ILC3s results in an atypical distribution of ILC3s in patients and mice with MAFLD, characterized by a significant reduction in ILC3s in the liver and an increase in ILC3s outside the liver. Moreover, disease severity is negatively correlated with the proportion of hepatic ILC3s. These hepatic ILC3s demonstrate a mitigating effect on hepatic steatosis through the release of IL-22. Mechanistically, WMT upregulates CXCR6 expression on ILC3s, thereby facilitating their migration to the liver of MAFLD mice via the CXCL16/CXCR6 axis, ultimately contributing to the amelioration of MAFLD. Overall, these findings highlight that WMT and targeting of liver-homing ILC3s could be promising strategies for the treatment of MAFLD.

Microbiota transplantation in restoring cesarean-related infant dysbiosis: a new frontier

C-section is crucial in reducing maternal and neonatal mortality when medically indicated, but one of its side effects could be the disruption of vertical transmission of maternal-infant microbiota during delivery, potentially leading to gut dysbiosis and increased disease risks in C-section infants. To address such dysbiosis, it seems reasonable to supplement "what is missing" during C-section procedure. This idea has prompted several clinical trials, including proof-of-concept, investigating interventions like vaginal microbial seeding, oral administration of maternal vaginal microbes and even oral administration of maternal fecal materials. Hereby, we have summarized these trials to help understand the current state of these researches, highlighting the predominantly pilot nature of most of these studies and emphasizing the need for well-designed studies with larger sample to guide evidence-based medicine in the future.

Recipient microbiome-related features predicting metabolic improvement following fecal microbiota transplantation in adults with severe obesity and metabolic syndrome: a secondary analysis of a phase 2 clinical trial

Microbial-based therapeutics in clinical practice are of considerable interest, and a recent study demonstrated fecal microbial transplantation (FMT) followed by dietary fiber supplements improved glucose homeostasis. Previous evidence suggests that donor and recipient compatibility and FMT protocol are key determinants, but little is known about the involvement of specific recipient factors. Using data from our recent randomized placebo-control phase 2 clinical trial in adults with obesity and metabolic syndrome, we grouped participants that received FMT from one of 4 donors with either fiber supplement into HOMA-IR responders (n = 21) and HOMA-IR non-responders (n = 8). We further assessed plasma bile acids using targeted metabolomics and performed subgroup analyzes to evaluate the effects of recipient parameters and gastrointestinal factors on microbiota engraftment and homeostatic model assessment of insulin resistance (HOMA2-IR) response. The baseline fecal microbiota composition at genus level of recipients could predict the improvements in HOMA2-IR at week 6 (ROC-AUC = 0.70). Prevotella was identified as an important predictor, with responders having significantly lower relative abundance than non-responders (p = .02). In addition, recipients displayed a highly individualized degree of microbial engraftment from donors. Compared to the non-responders, the responders had significantly increased bacterial richness (Chao1) after FMT and a more consistent engraftment of donor-specific bacteria ASVs (amplicon sequence variants) such as Faecalibacillus intestinalis (ASV44), Roseburia spp. (ASV103), and Christensenellaceae spp. (ASV140) (p < .05). Microbiota engraftment was strongly associated with recipients' factors at baseline including initial gut microbial diversity, fiber and nutrient intakes, inflammatory markers, and bile acid derivative levels. This study identified that responders to FMT therapy had a higher engraftment rate in the transplantation of specific donor-specific microbes, which were strongly correlated with insulin sensitivity improvements. Further, the recipient baseline gut microbiota and related factors were identified as the determinants for responsiveness to FMT and fiber supplementation. The findings provide a basis for the development of precision microbial therapeutics for the treatment of metabolic syndrome.

The Role of Gut Microbiota and Leaky Gut in the Pathogenesis of Food Allergy

Food allergy (FA) is a growing public health concern, with an increasing prevalence in Western countries. Increasing evidence suggests that the balance of human gut microbiota and the integrity of our intestinal barrier may play roles in the development of FA. Environmental factors, including industrialization and consumption of highly processed food, can contribute to altering the gut microbiota and the intestinal barrier, increasing the susceptibility to allergic sensitization. Compositional and functional alterations to the gut microbiome have also been associated with FA. In addition, increased permeability of the gut barrier allows the translocation of allergenic molecules, triggering Th2 immune responses. Preclinical and clinical studies have highlighted the potential of probiotics, prebiotics, and postbiotics in the prevention and treatment of FA through enhancing gut barrier function and promoting the restoration of healthy gut microbiota. Finally, fecal microbiota transplantation (FMT) is now being explored as a promising therapeutic strategy to prevent FA in both experimental and clinical studies. In this review article, we aim to explore the complex interplay between intestinal permeability and gut microbiota in the development of FA, as well as depict potential therapeutic strategies.

Potential of Fecal Microbiota Transplantation to Prevent Acute GVHD: Analysis from a Phase II Trial

PURPOSE

Intestinal microbiota disruptions early after allogeneic hematopoietic cell transplantation have been associated with increased risk for acute GVHD (aGVHD). In our recent randomized phase II trial of oral, encapsulated, third-party fecal microbiota transplantation (FMT) versus placebo, FMT at the time of neutrophil recovery was safe and ameliorated dysbiosis. Here, we evaluated in post hoc analysis whether donor microbiota engraftment after FMT may protect against aGVHD.

EXPERIMENTAL DESIGN

We analyzed pre- and post-FMT stool samples and estimated donor microbiota engraftment (a preplanned secondary endpoint) by determining the fraction of post-FMT microbiota formed by unique donor taxa (donor microbiota fraction; dMf).

RESULTS

dMf was higher in patients who later developed grade I or no aGVHD (median 33.9%; range, 1.6%-74.3%) than those who developed grade II-IV aGVHD (median 25.3%; range, 2.2%-34.8%; P = 0.006). The cumulative incidence of grade II-IV aGVHD by day 180 was lower in the group with greater-than-median dMf than the group with less-than-median dMf [14.3% (95% confidence interval, CI, 2.1-37.5) vs. 76.9% (95% CI, 39.7-92.8), P = 0.008]. The only determinant of dMf in cross-validated least absolute shrinkage and selection operator (LASSO)-regularized regression was the patient's pre-FMT microbiota diversity (Pearson correlation coefficient -0.82, P = 1.6 × 10-9), indicating more potent microbiota modulation by FMT in patients with more severe dysbiosis. Microbiota network analysis revealed major rewiring including changes in the most central nodes, without emergence of keystone species, as a potential mechanism of FMT effect.

CONCLUSIONS

FMT may have protective effects against aGVHD, especially in patients with more severe microbiota disruptions.

The Gut Microbiome from a Biomarker to a Novel Therapeutic Strategy for Immunotherapy Response in Patients with Lung Cancer

The gastrointestinal microbiome has been shown to play a key role in determining the responses to cancer immunotherapy, including immune checkpoint inhibitor (ICI) therapy and CAR-T. In patients with non-small cell lung cancer (NSCLC), increasing evidence suggests that a microbiome composition signature is associated with clinical response to ICIs as well as with the development of immune-related adverse events. In support of this, antibiotic (ATB)-related dysbiosis has been consistently linked with the deleterious impact of ICI response, shortening the overall survival (OS) among patients on ATBs prior to ICI initiation. In parallel, several preclinical experiments have unravelled various strategies using probiotics, prebiotics, diet, and fecal microbiota transplantation as new therapeutic tools to beneficially shift the microbiome and enhance ICI efficacy. These approaches are currently being evaluated in clinical trials and have achieved encouraging preliminary results. In this article, we reviewed the recent studies on the gut microbiome as a potential biomarker and an adjuvant therapy to ICIs in NSCLC patients.