Microbiota transplant therapy is an emerging therapy for inflammatory bowel disease, but factors influencing its efficacy and mechanism remain poorly understood. In this narrative review, we outline key elements affecting therapeutic outcomes, including donor factors (such as age and patient relationship), recipient factors, control selection, and elements impacting engraftment and its correlation with clinical response. We also examine potential mechanisms through inflammatory bowel disease trials, focusing on the interplay between the microbiota, host, and immune system. Finally, we briefly explore potential future directions for microbiota transplant therapy and promising emerging treatments.

Inflammatory Bowel Disease (IBD) is a spectrum of chronic inflammatory diseases of the intestine that includes subtypes of ulcerative colitis (UC) and Crohn's Disease (CD) and currently has no cure. While IBD results from a complex interplay between genetic, environmental, and immunological factors, sequencing advances over the last 10-15 years revealed signature changes in gut microbiota that contribute to the pathogenesis of IBD. These findings highlight IBD as a disease target for microbiome-based therapies, with the potential to treat the underlying microbial pathogenesis and provide adjuvant therapy to the emerging spectrum of advanced therapies for IBD. Building on the success of fecal microbiota transplantation (FMT) for Clostridioides difficile infection, therapies targeting gut microbiota have emerged as promising approaches for treating IBD; however, unique aspects of IBD pathogenesis highlight the need for more precision in the approach to microbiome therapeutics that leverage aspects of recipient and donor selection, diet and xenobiotics, and strain-specific interactions to enhance the efficacy and safety of IBD therapy. This review focuses on both pre-clinical and clinical studies that support the premise for microbial therapeutics for IBD and aims to provide a framework for the development of precision microbiome therapeutics to optimize clinical outcomes for patients with IBD.

The development of fecal microbiota transplantation and defined live biotherapeutic products for the treatment of human disease has been an empirically driven process yielding a notable success of approved drugs for the treatment of recurrent Clostridioides difficile infection. Assessing the potential of this therapeutic modality in other indications with mixed clinical results would benefit from consistent quantitative frameworks to characterize drug potency and composition and to assess the impact of dose and composition on the frequency and duration of strain engraftment. Monitoring these drug properties and engraftment outcomes would help identify minimally sufficient sets of microbial strains to treat disease and provide insights into the intersection between microbial function and host physiology. Broad and correct usage of strain detection methods is essential to this advancement. This article describes strain detection approaches, where they are best applied, what data they require, and clinical trial designs that are best suited to their application.

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by recurrent colonic inflammation. Standard treatments focus on controlling inflammation but remain ineffective for one-third of patients. This underscores the need for alternative approaches, such as fecal microbiota transplantation (FMT), which transfers healthy donor microbiota to patients. The role of viruses in this process, however, remains underexplored. To address this, we analyzed the gut virome using metagenomic sequencing of enriched viral particles from 320 longitudinal fecal samples of 44 patients enrolled in the RESTORE-UC FMT trial. Patients were treated with FMTs from healthy donors (allogenic, treatment) or themselves (autologous, control). We found that colonic inflammation, both its presence and location, had a greater impact on the gut virome than FMT itself. In autologous FMT patients, the virome was unstable and showed rapid divergence over time, a phenomenon we termed virome drift. In allogenic FMT patients, the virome temporarily shifted toward the healthy donor, lasting up to 5 weeks and primarily driven by microviruses. Notably, two distinct virome configurations were identified and linked to either healthy donors or patients. In conclusion, inflammation strongly affects the gut virome in UC patients, which may lead to instability and obstruct the engraftment of allogeneic FMT.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract influenced by genetic, environmental, immune, and microbial factors. Reduced gut microbial diversity and elevated proinflammatory bacteria levels in IBD disrupt mucosal immunity, barrier function, and inflammatory pathways. Fecal microbiota transplantation (FMT) is a potential therapy to restore microbial balance. Studies suggest that FMT may induce remission in mild-to-moderate ulcerative colitis but show limited efficacy in Crohn's disease and pouchitis. Donor microbiota colonization correlates with remission, but varied study designs challenge findings. Further research is required to standardize FMT protocols, optimize donor selection, and ensure long-term safety.

This review and commentary outline the strong rationale for normalizing the abnormal microbiota of patients with ulcerative colitis, Crohn's disease, and pouchitis and focus on strategies to improve current variable outcomes of fecal microbial transplant (FMT) in ulcerative colitis. Applying lessons from successful FMT therapy of recurrent Clostridioides difficile and insights from basic scientific understanding of host/microbial interactions provide strategies to enhance clinical outcomes in IBD. We outline promising approaches to develop novel-defined consortia of live biotherapeutic products and combination treatments to improve current results and to optimize and personalize treatment approaches in individual patients and disease subsets.

Fecal microbiota transplantation (FMT) is highly effective in preventing Clostridioides difficile recurrence by restoring gut microbiota composition and function. However, the impact of recent antibiotic use, a key exclusion criterion for stool donors, on gut microbiota recovery is poorly understood.

We investigated microbial recovery dynamics following antibiotic use in three long-term stool donors from Canada and Finland. Using longitudinal stool sampling, metagenomic sequencing, and qPCR, we assessed changes in bacterial diversity, community composition, microbial functions, the gut phageome, and the risk of transmitting antibiotic-resistant genes (ARGs).

Antibiotics caused lasting disruption to bacterial communities, significantly reducing important taxa like Bifidobacterium bifidum, Blautia wexlerae, Akkermansia muciniphila, Eubacterium sp. CAG 180, and Eubacterium hallii, with effects persisting for months. Functional analyses revealed alterations in housekeeping genes critical for energy production and biosynthesis, with no direct links to key health-related pathways. Antibiotics also disrupted viral populations, decreasing diversity and increasing crAssphage abundance, reflecting disrupted host-bacteriophage dynamics. No significant increase in clinically important ARGs was detected.

These findings highlight the unpredictable and complex recovery of gut microbiota post-antibiotics. Individualized suspension periods in donor programs, guided by metagenomic analyses, are recommended to optimize FMT outcomes in various indications by considering antibiotic spectrum, duration, and host-specific factors.

Nonalcoholic fatty liver disease (NAFLD) is a growing global health concern, impacting approximately 32.4% of the worldwide population. As a disease linked to metabolic dysfunction, NAFLD continues to rise alongside global increases in obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome. There is considerable evidence indicating that NAFLD disproportionately affects racial, ethnic, and minority groups, although the exact reasons for these disparities remain elusive. Contributing factors to this disease may include socioeconomic status, cultural influences, stress, genetic factors, and lifestyle choices. Emerging evidence suggests that these causal factors could influence epigenetic mechanisms, particularly DNA methylation and histone modifications, as well as the composition and diversity of gut microbiota. Nevertheless, there is a scarcity of research that comprehensively examines the interplay between epigenetic changes and gut microbiome variations in relation to NAFLD disparities across different racial and ethnic populations globally. This paper intends to (i) explore the connections between NAFLD, ethnic disparities, gut microbiota composition, and epigenetic alterations, while reviewing pertinent studies that illustrate how these factors contribute to health inequities among various ethnic groups impacted by this disease; (ii) explore potential therapeutic targets and biomarkers to advance the management of NAFLD; and (iii) provide insights to enhance our understanding of the mechanisms associated with this disease, thereby promoting further research in this field. Advancements in this area are anticipated to enhance our understanding of disease susceptibilities in at-risk groups and to provide new therapeutic options for NAFLD and its associated complications.

The prevalence of allergic diseases has been rising, paralleling lifestyle changes and environmental exposures that have altered human microbiome composition. This review article examines the intricate relationship between the gut microbiome and allergic diseases, emphasizing the potential of fecal microbiota transplantation as a promising novel treatment approach. It explains how reduced microbial exposure in modern societies contributes to immune dysregulation and the increasing incidence of allergies. The discussion also addresses immune homeostasis and its modulation by the gut microbiome, highlighting the shift from eubiosis to dysbiosis in allergic conditions. Furthermore, this article reviews existing studies and emerging research on the role of fecal microbiota transplantation in restoring microbial balance, providing insights into its mechanisms, efficacy, and safety.

Faecal microbiota transplantation (FMT) is an effective treatment for patients with recurrent Clostridioides difficile infection, but donor selection can influence its clinical success. We aimed to investigate the effect of clinical donor characteristics on FMT outcomes in patients with C difficile infection.

In this single-centre, prospective cohort study, we included all donors who fulfilled the national criteria for faeces donation and delivered donations to the Centre for Faecal Microbiota Transplantation, Aarhus University Hospital, Denmark, between May 2, 2016, and Oct 31, 2023, and corresponding recipients treated with one-dose FMT for primary or recurrent C difficile infection. In mixed-effects models, we evaluated the effect of donor sex, age, BMI, smoking status, donation stool consistency, total donation weight, antibiotic use, Helicobacter pylori carriage, birth mode, donor-recipient sex concordance, and the alpha diversity of faeces donations on FMT outcomes in recipients. The primary outcome was the resolution of diarrhoea associated with C difficile infection in patients 8 weeks after FMT.

Among 145 blood donors who also donated faeces, 115 (79·3%) were men and 30 (20·7%) were women. 90 (62·1%) provided faeces for 1351 evaluable FMTs in 952 patients with C difficile infection. 1037 (76·8%) FMTs were administered through oral capsules, 151 (11·2%) via colonoscopy, and 163 FMTs (12·1%) via nasojejunal tube. Antibiotic use 3-12 months before donation decreased the effectiveness of FMT (odds ratio 0·55 [95% CI 0·33-0·91]; p=0·019). Compared with donations with a Bristol Stool Form Scale (BSFS) score of 3, donations with a score of 4 (odds ratio 1·38 [95% CI 1·04-1·83]; p=0·024) and 5 or above (2·89 [1·33-6·26]; p=0·0072) showed improved FMT effectiveness. Donor sex, BMI, smoking status, H pylori carriage, birth mode, total donation weight, and donor-recipient sex concordance did not affect FMT outcomes.

Expanding current donor selection criteria to avoid antibiotic use in the 12 months preceding donation and including donations with a BSFS score of 5 might improve FMT outcomes for patients with C difficile infection. Our findings call for the revision of current clinical donor screening practices, and future studies could further optimise the criteria for selecting optimal faeces donors.

Innovation Fund Denmark.

Advances in understanding the pathogenesis of inflammatory bowel disease (IBD) point toward a key role of the gut microbiome. We review the data describing the changes in the gut microbiome from IBD case-control studies and compare these findings with emerging data from studies of the preclinical phase of IBD. What is apparent is that assessing changes in the composition and function of the gut microbiome during the preclinical phase helps address confounding factors, such as disease activity and drug therapy, which can directly influence the gut microbiome. Understanding these changes in the predisease phase provides a means of predicting IBD in high-risk populations and offers insights into possible mechanisms involved in disease pathogenesis. Finally, we discuss strategies to use this information to design interventions aimed at modulating the microbiome as a means of preventing or delaying the onset of IBD.

Recent systematic reviews and meta-analyses (SRMAs) have shown inconsistent effectiveness of FMT among patients with IBD. This study aimed to appraise the evidence for clinically relevant outcomes with FMT in patients with IBD using published SRMAs.

We searched major databases from inception through Nov 2023 to identify SRMAs assessing the effectiveness of FMT in patients with IBD. Primary outcomes included clinical remission, clinical response, endoscopic remission/response, a composite endpoint, and adverse effects. We included SRMAs investigating FMT's effect in patients with IBD using RCTs and observational studies data. Methodological quality and evidence certainty were assessed using AMSTAR 2 and GRADE.

Out of 106 citations, 16 SRMAs were included with varying study sizes (2 to 60 primary studies) and participants (112 to 1169 per SRMA). Five SRMAs assessed FMT in IBD, while 11 focused on Ulcerative Colitis (UC). Seven SRMAs included RCTs only, and nine included both RCTs and observational studies. Methodological quality was critically low in 9 SRMAs (56%) and low in 7 studies (44%). FMT showed clinical remission benefit in all 16 SRMAs, with varying certainty: 3 high, 4 moderate, 4 low, and 5 very low. Endoscopic remission/response was reported in 5 meta-analyses on UC, with 1 high, 3 moderate, and 1 very low certainty. Combined clinical remission and endoscopic response were reported in 3 SRMAs on UC, with 1 low and 2 moderate certainty. Adverse events were reported in 6 SRMAs, with 1 high, 3 moderate, 1 low, and 1 very low certainty.

Current evidence shows potential benefits of FMT in IBD, particularly UC, supported by significant associations in 16 meta-analyses. However, poor methodological quality and variability in evidence certainty call for high-quality RCTs to strengthen the evidence.

The gut microbiota is a diverse ecosystem that significantly impacts human health and disease. This article focuses on how the gut microbiota interacts with inflammatory bowel diseases and colorectal tumors, especially through immune regulation. The gut microbiota plays a role in immune system development and regulation, while the body's immune status can also affect the composition of the microbiota. These microorganisms exert pathogenic effects or correct disease states in gastrointestinal diseases through the actions of toxins and secretions, inhibition of immune responses, DNA damage, regulation of gene expression, and protein synthesis. The microbiota and its metabolites are essential in the development and progression of inflammatory bowel diseases and colorectal tumors. The complexity and bidirectionality of this connection with tumors and inflammation might render it a new therapeutic target. Hence, we explore therapeutic strategies for the gut microbiota, highlighting the potential of probiotics and fecal microbiota transplantation to restore or adjust the microbial community. Additionally, we address the challenges and future research directions in this area concerning inflammatory bowel diseases and colorectal tumors.

We aimed to determine the diagnostic and prognostic potential of baseline microbiome profiling in inflammatory bowel disease (IBD).

Participants with ulcerative colitis (UC), Crohn's disease (CD), suspected IBD, and non-IBD symptomatic controls were included in the prospective population-based cohort Inflammatory Bowel Disease in South-Eastern Norway III (third iteration) based on suspicion of IBD. The participants donated fecal samples that were analyzed with 16S rRNA sequencing. Disease course severity was evaluated at the 1-year follow-up. A stringent statistical consensus approach for differential abundance analysis with 3 different tools was applied, together with machine learning modeling.

A total of 1404 individuals were included, where n = 1229 samples from adults were used in the main analyses (n = 658 UC, n = 324 CD, n = 36 IBD-U, n = 67 suspected IBD, and n = 144 non-IBD symptomatic controls). Microbiome profiles were compared with biochemical markers in machine learning models to differentiate IBD from non-IBD symptomatic controls (area under the receiver operating curve [AUC] 0.75-0.79). For UC vs controls, integrating microbiome data with biochemical markers like fecal calprotectin mildly improved classification (AUC 0.83 to 0.86, P < .0001). Extensive differences in microbiome composition between UC and CD were identified, which could be quantified as an index of differentially abundant genera. This index was validated across published datasets from 3 continents. The UC-CD index discriminated between ileal and colonic CD (linear regression, P = .008) and between colonic CD and UC (P = .005), suggesting a location-dependent gradient. Microbiome profiles outperformed biochemical markers in predicting a severe disease course in UC (AUC 0.72 vs 0.65, P < .0001), even in those with a mild disease at baseline (AUC 0.66 vs 0.59, P < .0001).

Fecal microbiome profiling at baseline held limited potential to diagnose IBD from non-IBD compared with standard-of-care. However, microbiome shows promise for predicting future disease courses in UC.

The enteric microbiota drives inflammation in Crohn's disease. Yet, there are no placebo controlled trials evaluating the efficacy and safety of faecal microbiota transplantation (FMT) in inducing and maintaining remission in patients with active Crohn's disease. The Microbial Restoration (MIRO) study aims to establish this evidence.

At two specialist inflammatory bowel disease centres, 120 enrolled patients will have a 3-week period of diet optimisation (removal of ultra-processed foods) together with a 7-day course of antibiotics (to facilitate subsequent FMT engraftment). Patients will then be stratified to upper gut (for disease proximal to the splenic flexure) or lower gut (distal to the splenic flexure) disease. Patients will then be randomised in a 2:1 ratio to receive anaerobically prepared stool or placebo for 8 weeks either by gastroscopy, or colonoscopy and enemas. Clinical response at 8 weeks (Crohn's Disease Activity Index (CDAI) reduction ≥100 points or to <150 points) is the primary outcome measure. Non-responders to placebo and partial responders to FMT (CDAI decrease <100 but >70) receive FMT for weeks 8-16.Patients achieving clinical response from FMT after 8 or 16 weeks will be randomised in a 1:1 ratio to either a 44-week maintenance phase of FMT or placebo. Patients will receive FMT from one donor throughout the study.The MIRO study will establish whether FMT is an effective and safe therapy to induce and maintain remission in patients with active Crohn's disease.

Ethical approval has been received by the St Vincent's Hospital Melbourne Human Research Ethics Committee (HREC-A 084/21). The results will be disseminated in peer-reviewed journals and presented at international conferences.

ClinicalTrials.gov: NCT04970446; Registered on 20 July 2021.

Fecal microbiota transplantation (FMT) has been shown to restore gut microbiome composition with an acceptable safety profile. FMT in inflammatory bowel disease, specifically ulcerative colitis (UC), has been investigated. We aimed to assess the efficacy of FMT in inducing UC remission.

PubMed, Scopus, Google Scholar, and clinicaltrials.gov were searched for randomized control trials that assessed FMT in inducing UC remission. The primary outcome was combined clinical and endoscopic remission. Secondary outcomes were clinical remission, endoscopic remission, post-treatment overall adverse events, and colitis. Sensitivity analyses, meta-regression, bias assessment, and grading of certainty of evidence were performed.

A total of 14 studies including 600 patients (55.8% male; median age 40.7 years) were assessed. FMT was used in 299 patients and associated with significantly higher odds of combined clinical and endoscopic remission (OR 2.25, 95% CI 1.54, 3.3; p < 0.0001), clinical remission (OR 2.02, 95% CI 1.4, 2.93; p = 0.0002), and endoscopic remission (OR 1.95, 95% CI 1.17, 3.28; p = 0.011). The odds of post-treatment overall adverse events (OR 1.24, 95% CI 0.79, 1.95; p = 0.34) and colitis (OR 0.85, 95% CI 0.52, 1.93; p = 0.512) were similar between groups. Compared with baseline, FMT was more effective when biologics (OR 2.71), steroids (OR 2.27), or methotrexate (OR 3.07) were used as pre-FMT treatment. Oral delivery of FMT (OR 3.15) and pooled donors (OR 3.32) led to higher odds of remission. On meta-regression, pooled donors and methotrexate pre-treatment were associated with an increased likelihood of remission.

FMT is promising in inducing UC remission. Administration of medical treatments before FMT may help achieve higher remission rates. Current evidence shows that oral delivery of FMT and multidonor FMT may confer better results.

The cervicovaginal microbiome (CVM) is increasingly being considered as an important aspect of women's health, particularly in relation to the risk and progression of sexually transmitted infections (STIs). CVM composition varies significantly between individuals and is shaped by factors including diet, age, environmental exposures, and lifestyle. Understanding these influences may shed light on how microbial imbalances contribute to infection susceptibility and the development of reproductive health disorders. Five distinct community state types (CSTs) classify common CVM compositions. Most CSTs (I, II, III, V) are characterized by a dominant Lactobacillus species and are associated with better or neutral reproductive health, including reduced coincident detection of STIs such as Chlamydia trachomatis. In contrast, CST IV is composed of diverse, predominantly anaerobic, microbial species and is associated with CVM dysbiosis, bacterial vaginosis, and a heightened risk of STI acquisition. This review examines the complex interplay between the CVM, C. trachomatis infection, and host immune responses, highlighting the role of metabolites such as short-chain and long-chain fatty acids, indole, and iron in modulating pathogen survival and host defenses. Additionally, the impacts of CVM composition on C. trachomatis persistence, ascension, and clearance are discussed, alongside co-infection dynamics with pathogens like Neisseria gonorrhoeae and Mycoplasma genitalium.

Fecal microbiota transplantation (FMT) has shown efficacy for the treatment of ulcerative colitis but with variable response between patients and trials. The mechanisms underlying FMT's therapeutic effects remains poorly understood but is generally assumed to involve engraftment of donor microbiota into the recipient's microbiome. Reports of microbial engraftment following FMT have been inconsistent between studies. Here, we investigate microbial engraftment in a previous randomized controlled trial (NCT01545908), in which FMT was sourced from a single donor, using amplicon-based profiling, shotgun metagenomics, and culture-enriched metagenomics. Placebo samples were included to estimate engraftment noise, and a significant level of false-positive engraftment was observed which confounds the prediction of true engraftment. We show that analyzing engraftment across multiple patients from a single donor enhances the accuracy of detection. We identified a unique set of genes engrafted in responders to FMT which supports strain displacement as the primary mechanism of engraftment in our cohort.

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.

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.

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."

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.

Clinical applications of fecal microbiota transplantation (FMT) for treating ulcerative colitis (UC) have shown promising results. However, whether the beneficial effects of FMT are due to the transfer and colonization of donor-derived species in patients remains unclear. Here, we investigated the factors affecting the efficacy of the administration of triple antibiotics (A-FMT) and the criteria for appropriate donor and patient-donor matching.

Ninety-seven patients with active UC who were enrolled between March 2014 and October 2019 underwent FMT. The clinical features were assessed based on a reduction in Lichtiger's clinical activity index 4 weeks after A-FMT, with long-term responders (LTR) defined as those with no increase or intensification within 12 months after A-FMT. Microbiome analysis was performed on 147 fecal samples (pre-A-FMT, post-A-FMT, and donor) from 49 patient-donor combinations that were assigned using the one-patient-to-one-donor strategy.

Of the 97 patients, 61 achieved a clinical response, and of those, 35 were classified as having clinical remission. The efficacy of A-FMT was affected by UC severity and previous administration of steroids (P = .027), immunosuppressants (P = .049), and biologics (P = .029). Effective donors were rich in taxa such as Bacteroidota, which are lost in UC, and the abundances of "patient-origin" and "new-amplicon sequence variant" taxa were significantly lower in Responders compared to Nonresponders (Remission; P = .03, LTR; P = .05). "Donor-derived" amplicon sequence variant sequences, Oscillospiraceae UCG-002 and Alistipes, were significantly enriched in Responders (P < .05). Our results showed that the taxonomic composition of patients and the similarity of Bacteroides and butyric-acid-producing bacteria in the patient-donor microbiota significantly influenced A-FMT efficacy (P < .05).

This study provides important insights for developing patient-tailored FMT-based therapies for UC.

The human gastrointestinal tract harbors a vast array of microorganisms, which play essential roles in maintaining metabolic balance and immune function. While bacteria dominate the gut microbiome, fungi represent a much smaller, often overlooked fraction. Despite their relatively low abundance, fungi may significantly influence both health and disease. Advances in next-generation sequencing, metagenomics, metatranscriptomics, metaproteomics, metabolomics, and computational biology have provided novel opportunities to study the gut mycobiome, shedding light on its composition, functional genes, and metabolite interactions. Emerging evidence links fungal dysbiosis to various diseases, including inflammatory bowel disease, colorectal cancer, metabolic disorders, and neurological conditions. The gut mycobiome also presents a promising avenue for precision medicine, particularly in biomarker discovery, disease diagnostics, and targeted therapeutics. Nonetheless, significant challenges remain in effectively integrating gut mycobiome knowledge into clinical practice. This review examines gut fungal microbiota, highlighting analytical methods, associations with human diseases, and its potential role in precision medicine. It also discusses pathways for clinical translation, particularly in diagnosis and treatment, while addressing key barriers to implementation.

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic condition characterized by abnormal immune responses and intestinal inflammation. Emerging evidence highlights the vital role of gut microbiota in IBD's onset and progression. Recent advances have shaped diagnostic and therapeutic strategies, increasingly focusing on microbiome-based personalized care. Methodology: this review covers studies from 2004 to 2024, reflecting the surge in research on luminal microbial ecology in IBD. Human studies were prioritized, with select animal studies included for mechanistic insights. Only English-language, peer-reviewed articles - clinical trials, systematic reviews, and meta-analyses - were considered. Studies without clinical validation were excluded unless offering essential insights. Searches were conducted using PubMed, Scopus, and Web of Science.

we explore mechanisms for managing IBD-related microbiota, including microbial markers for diagnosis and novel therapies such as fecal microbiota transplantation, metabolite-based treatments, and precision microbiome modulation. Additionally, we review technologies and diagnostic tools used to analyze gut microbiota composition and function in clinical settings. Emerging data supporting personalized therapeutic strategies based on individual microbial profiles are discussed.

Standardized microbiome research integration into clinical practice will enhance precision in IBD care, signaling a shift toward microbiota-based personalized medicine.

This article provides an overview of the advancements in the application of fecal microbiota transplantation (FMT) in treating diseases related to intestinal dysbiosis. FMT involves the transfer of healthy donor fecal microbiota into the patient's body, aiming to restore the balance of intestinal microbiota and thereby treat a variety of intestinal diseases such as recurrent Clostridioides difficile infection (rCDI), inflammatory bowel disease (IBD), constipation, short bowel syndrome (SBS), and irritable bowel syndrome (IBS). While FMT has shown high efficacy in the treatment of rCDI, further research is needed for its application in other chronic conditions. This article elaborates on the application of FMT in intestinal diseases and the mechanisms of intestinal dysbiosis, as well as discusses key factors influencing the effectiveness of FMT, including donor selection, recipient characteristics, treatment protocols, and methods for assessing microbiota. Additionally, it emphasizes the key to successful FMT. Future research should focus on optimizing the FMT process to ensure long-term safety and explore the potential application of FMT in a broader range of medical conditions.

Inflammatory bowel disease (IBD) is an idiopathic gastrointestinal disease with drastically increasing incidence rates. Due to its multifactorial etiology, a precise investigation of the pathogenesis is extremely difficult. Although reductionist cell culture models and more complex disease models in animals have clarified the understanding of individual disease mechanisms and contributing factors of IBD in the past, it remains challenging to bridge research and clinical practice. Conventional 2D cell culture models cannot replicate complex host-microbiota interactions and stable long-term microbial culture. Further, extrapolating data from animal models to patients remains challenging due to genetic and environmental diversity leading to differences in immune responses. Human intestine organ-on-chip (OoC) models have emerged as an alternative in vitro model approach to investigate IBD. OoC models not only recapitulate the human intestinal microenvironment more accurately than 2D cultures yet may also be advantageous for the identification of important disease-driving factors and pharmacological interventions targets due to the possibility of emulating different complexities. The predispositions and biological hallmarks of IBD focusing on host-microbiota interactions at the intestinal mucosal barrier are elucidated here. Additionally, the potential of OoCs to explore microbiota-related therapies and personalized medicine for IBD treatment is discussed.

This qualitative review aims to summarize current knowledge on ventriculostomy-related infection (VRI) pathophysiology and its prevention. VRI generally occurs at day 10, mainly because of Gram-positive cocci , after a cerebrospinal fluid leak. Skin microbiota and biofilm seem to play a major role in VRI pathogenesis. Colonization of external ventricular drain by biofilm is universal and occurs quickly after catheter insertion. However, pathogens from the skin are more often associated with VRI than commensal bacteria. A review of proposed preventive measures shows that none has proven to be fully efficient. Periprocedural and prolonged systemic prophylactic antimicrobials have not shown to prevent VRIs and may promote the emergence of more resistant or pathogenic strains. Antimicrobial and silver-impregnated external ventricular drains, although promising, have not demonstrated preventive effects and may modify bacterial ecology. These results are consistent with the proposed pathophysiology. Finally, we will present a few propositions for future research that may help in improving our knowledge and thus better prevent VRIs. Until then, given the available data, limiting the duration of ventricular drainage may be the most attainable option to prevent VRIs.

Approximately one in every four patients with ulcerative colitis will develop acute severe ulcerative colitis (ASUC). Historically, this was managed with intravenous steroids and surgery when steroids failed. The use of rescue therapy.

This review summarizes the latest research in the management of hospitalized patients with ASUC. Covering the historical data and success of rescue therapy with cyclosporine and then with infliximab changed outcomes and reduced the risk of colectomy during the hospitalization and at 1 year. More recently, more biologics and small molecules have been approved and more patients present to the hospital with ASUC already failing anti-tumor necrosis factor antagonists. More recent studies have shown some efficacy of rescue therapy with other classes of biologics (e.g. interleukins and anti-integrins). The more recently approved small molecules (i.e. tofacitinib and Upadacitinib) have shown a rapid onset in therapeutic efficacy in as little as 1 day with sustained response at 1 year in reducing the risk of colectomy following ASUC.

In the expert opinion, we discuss the challenges in the treatment of patients with ASUC. We summarize the data of current biologics and new small molecules and their emerging roles in the management of ASUC.

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders primarily comprising two main conditions: ulcerative colitis and Crohn's disease. The gut microbiota's role in driving inflammation in IBD has garnered significant attention, yet the precise mechanisms through which the microbiota influences IBD pathogenesis remain largely unclear. Given the limited therapeutic options for IBD, alternative microbiota-targeted therapies-including prebiotics, probiotics, postbiotics, and symbiotics-have been proposed. While these approaches have shown promising results, microbiota modulation is still mainly considered an adjunct therapy to conventional treatments, with a demonstrated impact on patients' quality of life. Fecal microbiota transplantation (FMT), already approved for treating Clostridioides difficile infection, represents the first in a series of innovative microbiota-based therapies under investigation. Microbial biotherapeutics are emerging as personalized and cutting-edge tools for IBD management, encompassing next-generation probiotics, bacterial consortia, bacteriophages, engineered probiotics, direct metabolic pathway modulation, and nanotherapeutics. This review explores microbial modulation as a therapeutic strategy for IBDs, highlighting current approaches and examining promising tools under development to better understand their potential clinical applications in managing intestinal inflammatory disorders.

Fecal microbiota transplantation (FMT) represents a therapeutic approach that directly regulates the gut microbiota of recipients, normalizes its composition and reaping therapeutic rewards. Currently, in addition to its general application in treating Clostridium difficile (C. difficile) infection (CDI), FMT treatment has also been extended to the fields of other gastrointestinal diseases, infections, gut-liver or gut-brain axis disorders, metabolic diseases and cancer, etc. Prior to FMT, rigorous donor screening is essential to reduce the occurrence of adverse events. In addition, it is imperative to evaluate whether the recipient can safely and effectively undergo FMT treatment. However, the efficacy of FMT is influenced by the complex interactions between the gut microbiota of donor and recipient, the degree of donor microbiota engraftment is not necessarily positively related with the success rate of FMT. Furthermore, an increasing number of novel factors affecting FMT outcomes are being identified in recent clinical trials and animal experiments, broadening our understanding of FMT treatment. This article provides a comprehensive review of the application scenarios of FMT, the factors influencing the safety and efficacy of FMT from the aspects of both the donors and the recipients, and summarizes how these emerging novel regulatory factors can be combined to predict the clinical outcomes of patients undergoing FMT.

Colonization of co-evolved, species-specific microbes in early life plays a crucial role in gastrointestinal development and immune function. This study hypothesized that modern pig production practices have resulted in the loss of co-evolved species and critical symbiotic host-microbe interactions. To test this, we reintroduced microbes from wild boars (WB) into conventional piglets to explore their colonization dynamics and effects on gut microbial communities, metabolite profiles, and immune responses. At postnatal day (PND) 21, 48 piglets were assigned to four treatment groups: (i) WB-derived mixed microbial community (MMC), (ii) sow-derived MMC, (iii) a combination of WB and sow MMC (Mix), or (iv) Control (PBS). Post-transplantation analyses at PND 48 revealed distinct microbial communities in WB-inoculated piglets compared with Controls, with trends toward differentiation from Sow but not Mix groups. WB-derived microbes were more successful in colonizing piglets, particularly in the Mix group, where they competed with Sow-derived microbes. WB group cecal digesta enriched with Lactobacillus helveticus, Lactobacillus mucosae, and Lactobacillus pontis. Cecal metabolite analysis showed that WB piglets were enriched in histamine, acetyl-ornithine, ornithine, citrulline, and other metabolites, with higher histamine levels linked to Lactobacillus abundance. WB piglets exhibited lower cecal IL-1β and IL-6 levels compared with Control and Sow groups, whereas the Mix group showed reduced IFN-γ, IL-2, and IL-6 compared with the Sow group. No differences in weight gain, fecal scores, or plasma cytokines were observed, indicating no adverse effects. These findings support that missing WB microbes effectively colonize domestic piglets and may positively impact metabolite production and immune responses.IMPORTANCEThis study addresses the growing concern over losing co-evolved, species-specific microbes in modern agricultural practices, particularly in pig production. The implementation of strict biosecurity measures and widespread antibiotic use in conventional farming systems may disrupt crucial host-microbe interactions that are essential for gastrointestinal development and immune function. Our research demonstrates that by reintroducing wild boar-derived microbes into domestic piglets, these microbes can successfully colonize the gut, influence microbial community composition, and alter metabolite profiles and immune responses without causing adverse effects. These findings also suggest that these native microbes can fill an intestinal niche, positively impacting immune activation. This research lays the groundwork for future strategies to enhance livestock health and performance by restoring natural microbial populations that produce immune-modulating metabolites.

This study compared the protective effects of both live Lacticaseibacillus paracasei 6235 (LLP 6235) and heat-killed Lacticaseibacillus paracasei 6235 (HK-LP 6235) on ulcerative colitis. Using a dextran sulfate sodium (DSS)-induced colitis mouse model, we evaluated physiological state, colon tissue integrity, inflammatory factors, tight junction (TJ) proteins, and intestinal microbiota variations. The findings demonstrated that both LLP 6235 and HK-LP 6235 have the capacity to mitigate colitis damage, enhance TJ protein levels, and restore colon morphology. In addition, these interventions modulated the intestinal inflammatory response by inhibiting pro-inflammatory factors and upregulating anti-inflammatory factors through the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. Moreover, treatment with LLP 6235 and HK-LP 6235 significantly altered intestinal microbiota diversity, increased the relative abundance of beneficial bacteria, and regulated the short-chain fatty acid (SCFA) levels. Spearman correlation analysis revealed a strong association between TJ proteins, SCFAs, intestinal microbiota, and inflammatory response, suggesting that LLP 6235 and HK-LP 6235 may provide an effective approach to colitis prevention. In conclusion, LLP 6235 and HK-LP 6235 have similar abilities; furthermore, HK-LP 6235 modulated the intestinal microbiota through lipid metabolic pathways, resulting in a greater improvement. Moreover, considering the high stability and safety of prebiotics and their wide applicability, HK-LP 6235 is recommended for use as a modulator of intestinal inflammatory diseases.

The stability and metabolic functionality of donor microbiota are critical determinants of fecal microbiota transplantation (FMT) efficacy in inflammatory bowel disease (IBD). While probiotics show potential to enhance microbiota resilience, their role in optimizing donor microbiota for FMT remains underexplored.

This study investigated whether pretreatment of donor microbiota with L. plantarum GR-4 could improve FMT outcomes in a DSS-induced colitis model by modulating microbial stability, metabolic activity, and host-microbiome interactions.

Donor mice received L. plantarum GR-4 for 3 weeks to generate modified FMT (MFMT). DSS-colitis mice were treated with MFMT, conventional FMT, or 5-aminosalicylic acid (5-ASA). Multi-omics analyses and functional assays (stress resistance, engraftment efficiency) were used to evaluate therapeutic mechanisms.

GR-4 pretreatment conferred three key advantages to donor microbiota: Ecological stabilization: 1. GR-4-driven acidification (pH 3.97 vs. 4.59 for LGG, p < 0.0001) enriched butyrogenic Butyricicoccus (73 % butyrate increase, p < 0.05) and improved stress resistance to bile acids/gastric conditions (1.25 × survival vs. FMT). 2. Metabolic reprogramming: GR-4 metabolized 25.3 % of tryptophan (vs. 10.3 % for LGG) to generate immunomodulatory indoles (ILA, IAA), activating aryl hydrocarbon receptor (AHR) signaling and upregulating anti-inflammatory IL-10/IL-22. 3. Bile acid remodeling: MFMT restored sulfolithocholic acid and β-MCA levels, outperforming FMT in resolving DSS-induced dysregulation. MFMT achieved an 83 % remission rate (vs. 50 % for FMT), enhanced gut barrier integrity, and reversed colitis-associated metabolic dysregulation (e.g., elevated spermidine, 7-sulfocholic acid). Probiotic preconditioning improved donor engraftment by 1.25 × and enriched success-associated taxa (Sporobacter, Butyricimonas), while suppressing pathogens (Clostridium papyrosolvens).

L. plantarum GR-4 optimizes donor microbiota via pH-driven niche engineering, immunometabolic reprogramming, and bile acid modulation, addressing key limitations of conventional FMT. The multi-targeted efficacy of MFMT, evidenced by superior remission rates and metabolic restoration, establishes this approach as a translatable strategy for IBD therapy. This study establishes probiotic-enhanced FMT as a paradigm for precision microbiome interventions.

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.

Rigorous donor preselection on microbiota level, strict anaerobic processing, and repeated fecal microbiota transplantation (FMT) administration were hypothesized to improve FMT induction of remission in ulcerative colitis (UC).

The RESTORE-UC trial was a multi-centric, double-blind, sham-controlled, randomized trial. Patients with moderate to severe UC (defined by total Mayo 4-10) were randomly allocated to receive 4 anaerobic-prepared allogenic or autologous donor FMTs. Allogenic donor material was selected after a rigorous screening based on microbial cell count, enterotype, and the abundance of specific genera. The primary endpoint was steroid-free clinical remission (total Mayo ≤2, no sub-score >1) at week 8. A pre-planned futility analysis was performed after 66% (n = 72) of intended inclusions (n = 108). Quantitative microbiome profiling (n = 44) was performed at weeks 0 and 8.

In total, 72 patients were included, of which 66 received at least 1 FMT (allogenic FMT, n = 30 and autologous FMT, n = 36). At week 8, respectively, 3 and 5 patients reached the primary endpoint of steroid-free clinical remission (P = .72), indicating no treatment difference of at least 5% in favor of allogenic FMT. Hence, the study was stopped due to futility. Microbiome analysis showed numerically more enterotype transitions upon allogenic FMT compared with autologous FMT, and more transitions were observed when patients were treated with a different enterotype than their own at baseline (P = .01). Primary response was associated with lower total Mayo scores, lower bacterial cell counts, and higher Bacteroides 2 prevalence at baseline.

The RESTORE-UC trial did not meet its primary endpoint of increased steroid-free clinical remission at week 8. Further research should additionally consider patient selection, sterilized sham-control, increased frequency, density, and viability of FMT prior to administration.

gov, Number: NCT03110289.

The dysbiosis of the gut microbiota has been identified as a central factor in the pathogenesis of inflammatory bowel disease (IBD), a chronic condition characterized by frequent recurrence and various adverse effects of traditional therapies. While treatments targeting the gut microbiota show promise, their efficacy in IBD management still requires extensive evaluation. Our systematic review analyzes recent studies to elucidate the advancements and challenges in treating IBD using microbial-based therapies.

Through a comprehensive systematic review spanning key scientific databases-PubMed, Embase, Cochrane, Web of Science, Scopus, and Google Scholar-we scrutinized the impact of probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT) on individuals with IBD. Our detailed analysis covered study and participant demographics, along with seven key outcome measures: disease activity index, inflammatory markers, serum cytokines, microbiome composition, adverse effects, and the rates of remission and relapse.

From 6,080 initial search hits, we included 71 studies that assessed various interventions compared to placebo or standard medical therapy. Although there was notable variation in clinical results while assessing different outcomes, overall, probiotics, prebiotics, and synbiotics enhanced the success rates in inducing remission among IBD patients. Furthermore, we noted significant reductions in levels of pro-inflammatory markers and cytokines. Additionally, the requirement for steroids, hospitalization, and poor outcomes in endoscopic and histological scores were significantly reduced in individuals undergoing FMT.

Our investigation highlights the potential of targeting gut microbiota dysbiosis with microbial-based therapies in patients with IBD. We recommend conducting larger, placebo-controlled randomized trials with extended follow-up periods to thoroughly assess these treatments' clinical efficacy and safety before widespread recommendations for clinical application.

The impact of fecal microbiota transplantation (FMT) on the TLR4/MYD88/NF-kB signaling pathway in the colon in the ulcerative colitis model, as well as the incidence of anxiety behaviors caused by the colitis model was investigated.

Twenthy four ats were induced with ulcerative colitis using a 4 % acetic acid solution administered intrarectally and were subsequently treated with prednisolone and FMT. The study examined several indicators, such as TLR4, MYD88, and NF-κB mRNA expression, along with oxidative stress factors. Additionally, it examined the relationship between anxiety-related behaviors and colitis and assessed the pro-inflammatory cytokines in the hippocampus.

FMT led to lower disease score index and improved colon tissue pathology findings. This was associated with reduced mRNA expression of TLR4, MYD88, and NF-κB, as well as lower levels of TOS, and higher levels of TAC, GSH, and GSSG in colon tissues. FMT was found to reduce anxiety in both the open field and elevated plus maze tests. Additionally, levels of IL-6 and TNF-a were decreased in the hippocampus.

FMT suppressed acetic acid-induced colitis by inhibiting the TLR4/MYD88/NF-kB signaling pathway. FMT reduced anxiety in open field and plus maze tests, and resulted in decreased levels of IL-6 and TNF-a in the hippocampus.

Washed microbiota transplantation (WMT) has emerged as a promising therapeutic strategy for autism spectrum disorder (ASD), though the factors that influence its efficacy remain poorly understood. This study explores the impact of gastrointestinal (GI) symptoms on the effectiveness of WMT in ASD.

Clinical data encompassing ASD symptoms, GI disturbances, and sleep disorders were collected from patients with ASD undergoing WMT. The therapeutic impact of WMT and the contributing factors to its efficacy were assessed.

WMT significantly reduced scores on the Aberrant Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), and Sleep Disturbance Scale for Children (SDSC), alongside a significant reduction in the incidence of constipation, abnormal stool forms, and diarrhea (all p < 0.05). After six courses of WMT, substantial reductions were observed in ABC, CARS, and SDSC scores, with increased treatment courses correlating with greater improvement (p < 0.05). Multiple linear regression analysis revealed that WMT efficacy was enhanced in patients with pre-existing GI symptoms (diarrhea: β = 0.119, p < 0.001; abnormal stool form: β = 0.201, p < 0.001) and those receiving a higher number of treatment courses (β = 0.116, p < 0.001). Additionally, the analysis indicated that treatment outcomes were more favorable in patients who had not undergone adjunct interventions (β = -0.041, p = 0.002), had a longer disease duration (β = 0.168, p = 0.007), and exhibited more severe disease symptoms (β = 0.125, p < 0.001).

WMT significantly alleviates both ASD and GI symptoms, along with sleep disturbances, in affected individuals. Six treatment courses resulted in notable improvement, with increased course numbers further improving therapeutic outcomes. Furthermore, pre-treatment GI symptoms, such as diarrhea and abnormal stool forms, may influence the effectiveness of WMT. Notably, patients who did not receive additional interventions, had a prolonged disease duration, and presented with more severe symptoms experienced markedly improved treatment responses.