A hierarchically assembled oral formulation with drug-convertible carriers for targeted ulcerative colitis therapy through a three-pronged strategy

Inflammatory bowel disease (IBD), which consists of Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disorder of the intestine. The etiology is heterogeneous and multifactorial, including genetic susceptibility, immune-mediated tissue damage, and changes of lumen microenvironment, especially short-chain fatty acid (SCFA) producing bacteria. Several studies reported a decrease in SCFA concentration in both CD and UC. In fact, SCFAs has important roles in accelerating disease remission. This systematic review aimed to evaluate the changes in SCFA concentration, the composition of SCFA-producing bacteria, and SCFA metabolism in IBD. A literature search was conducted via PubMed, Scopus, and CENTRAL by selecting studies according to inclusion and exclusion criteria. The quality and risk of bias assessment were performed using the Newcastle-Ottawa Scale (NOS). Overall, 160 UC and 127 CD patients from 5 studies were reviewed. The SCFA concentration was significantly reduced (p <0.05) in both PC and UC. Moreover, there was a decrease in major SCFA-producing bacteria. Clostridium coccoides were significantly decreased in the feces of active UC (p = 0.015) and CD (p = 0.04). Clostridium leptum was decreased on intestinal mucosal biopsy of active CD and UC (p <0.0001). Faecalibacterium prausnitzii were decreased in active CD faeces (p <0.0001) and UC (p = 0.0001). Butyrate oxidation rate was also reported to decrease in UC compared to control (p<0.0001). In conclusion, the ability of major SCFA-producing bacterial production in IBD was diminished, which implies a decreased protective and anti-inflammatory effect of SCFA that altered its metabolism.

Background Microbiome modifying treatments show potential in favourably influencing outcomes of patients with mild-moderate Ulcerative Colitis (UC). In a proof-of-concept study, we tested the gastrointestinal tolerability of a novel, “eubiotic” diet (UC-TREAT), and assessed its effects on the gut microbiome and short chain fatty acid (SCFA) production in individuals with UC and healthy controls (HC). Methods In a controlled prospective trial, 36 adults (18 HC and 18 with quiescent UC, defined as SCCAI ≤5) underwent a 10-day “run-in” phase, followed by a 5-day introductory “ramping” phase, and a 10-day “full” dietary intervention with UC-TREAT. UC-TREAT is rich in fermentable carbohydrates (providing 35g/day fibre in addition to habitual intake), and includes daily consumption of 5 different fermented foods, 2 types of berries, and a multivitamin supplement. Faecal samples were collected before and after each study phase, in which microbiome (16S rRNA), bacterial load (quantitative PCR), SCFA (GC-FID) and faecal calprotectin (FCAL) were assessed. Gastrointestinal tolerance (GSRS-IBS), disease activity (SCCAI) and dietary intake were assessed throughout the study. Results Fibre intake doubled during UC-TREAT (9.8 vs 20.8g/1000kcal/day, p < 0.001) and fermented food consumption increased by 4.3 portions/d (p < 0.001) in all participants. In both participant groups, an increase was observed in faecal acetate [median (Q1:Q3) µmol/g: UC: +11.1 (-3.73, 21.5); HC: +15.2 (-0.57, 36.6), both p < 0.01], total SCFA [UC: +11.6 (2.38, 22.1) µmol/g, p = 0.006; HC: +23.1 (-0.76, 53.2), p = 0.015], and bacterial load [log10 16S rRNA gene copies/g, UC: +0.07 (0, 0.22), p = 0.03; HC: +0.06 (-0.04, 0.14), p = 0.07]. Butyrate also increased in UC participants [+2.79 (-0.75, 4.88) µmol/g, p = 0.03). UC participants reported a short-term increase in bloating [median score: +2 (0, 4.3), p = 0.012], while HC reported prolonged bloating [+2.5 (1, 3), p = 0.001] and a transient rise in constipation [+1 (0, 3), p = 0.03] and satiety [0 (0, 1), p = 0.03]. Disease activity score increased [0 (0, 1), p = 0.012], while all UC participants remained in clinical remission and FCAL remained unchanged in UC, but decreased in HC [-3.15 (-10.3, 0.71) mg/kg, p = 0.02]. Microbiome composition changed in UC patients (R2=1.2% p < 0.01), but not in HC; Abundance of Streptococcus, and Anaerostipes hadrus, a butyrate producer, increased in UC (p < 0.001). Conclusion UC-TREAT increased fibre-originating faecal SCFA, bacterial load, and SCFA-producing taxa, without negatively affecting FCAL or GI tolerance in quiescent UC. These proof-of-concept results should be replicated in a larger, well-controlled RCT. Conflict of interest: Ms. Mckirdy, Shona: No conflict of interest Gaya, Daniel: No conflict of interest Russell, Richard K.: Grant: Nestec Other: Abbvie, Celltrion, Janssen, Lilly, Nestle, Pharmacosmos, Pfizer Hansen, Richard: Personal Fees: Dr Hansen has received consultancy fees and travel support from 4D pharma. Macdonald, Jonathan: No conflict of interest Seenan, John Paul: No conflict of interest Nichols, Ben: No conflict of interest Koutsos, Athanasios: No conflict of interest Gerasimidis, Konstantinos: Grant: Nestle Health Science, Nutricia-Danone, Mylan Personal Fees: Abbott, Baxter, Nestle Health Science, Nutricia-Danone, Servier, Janssen

Dehydrocostus lactone attenuates ulcerative colitis via USP38-mediated histone H2B Deubiquitination to suppress NF-κB-driven inflammation.

To verify whether short chain fatty acids (SCFA) alter the proliferative and endoscopic pattern of the mucosa in ileal pouches of ulcerative colitis (UC) or familial adenomatous polyposis (FAP) patients. We studied patients after proctocolectomy carrying a pelvic ileal pouch for FAP or UC (noncanalized pouches in 10 UC and 4 FAP patients and canalized pouches in 6 UC and 5 FAP patients). Patients with noncanalized pouches were treated twice daily for one week with 30 ml of a SCFA solution (60 mM sodium acetate, 30 mM sodium propionate, 40 mM sodium butyrate, and 22 mM sodium chloride, pH 7); patients with canalized pouches were treated with the same solution twice daily for two weeks. Pouch mucosal biopsies were collected before and after SCFA. Mucosal proliferation was assessed by incorporation of [3H]thymidine in vitro and autoradiography. In UC patients proliferation did not vary in noncanalized pouches but was significantly reduced in canalized pouches after SCFA. In FAP patients SCFA did not alter proliferation. No significant effects of SCFA were observed on daily defecation frequency, endoscopic appearance, or histopathology of the pouches. SCFA do not control inflammation and clinical functions but reduce cell proliferation in UC patients. On the contrary, FAP patients are refractory to SCFA.

Background. The pathogenesis of chronic inflammatory bowel disease (IBD) is still not fully clarified. It is known that disorders of the intestinal microbiota lead to an increased intestinal permeability, activation of mucous and adaptive immunity, impaired production and intestinal absorption of short-chain fatty acids (SCFA). The ratio of acetic, propionic, butyric acids is an important indicator of the integrity of the intestinal microbial community. Thus, the study of the composition of the intestinal microbiota and the concentrations of fecal SCFA is a very promising approach to broadening the understanding of IBD pathogenesis. The purpose of our study was to determine the features of the production of fecal SCFA and the composition of colon microbiota in patients with IBD. Materials and methods. The study, which was carried out at the Department of Intestinal Diseases of the Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine, involved 74 patients with IBD with an average age of (43.2±1.8) years, who according to nosology were divided into 2 groups: group I— those with ulcerative colitis (UC) (n=66), group II— individuals with Crohn’s disease (CD) (n=8). The diagnoses of CD and UC were established according to generally accepted diagnostic standards in gastroenterology. Determination of fecal SCFA was carried out by chromatographic method with the use of hardware-software complex for medical researches on the basis of the gas chromatographer Chromateс Crystal 5000. The intestinal microflora was evaluated using a microbiological study of the colon content. Results. Patients with IBD had significant changes in the spectrum of SCFA, which were similar in both UC and CD: a decrease in acetic acid in the UC group by 5.7 times, in the CD group by 10.5 times (p<0.05), butyric acid in the UC group by 1.6 times, in the CD group by 1.5 times (p<0.05), and an increase in propionic acid in the UC group by 4 times and in the CD group by 3.3 times (p<0.05) compared with the control group. There was also a significant increase in the anaerobic index in patients with IBD. Microbiological study of feces showed a significant decrease in Lactobacillus, which was observed in all patients with IBD, as well as a decrease in Bifidobacterium in 19.7% of those with UC and in 37.5% with CD. There was a decrease of other representatives of the normal microflora: Enterococci (in 15.2% in the UC group and 25% in the CD group) and Escherichia coli (in 15.2% in the UC group and 12.5% in the CD group). Excessive growth of opportunistic flora was also detected: hemolytic Escherichia coli was increased in 19.7% of patients with UC and in 12.5% of those with CD; Proteus was detected in 12.1% of people with UC and in 37.5% with CD. The excessive growth of Candida was found in 43.9% of patients in the UC group and in 87.5% of individuals with CD. Conclusions. Quantitative and qualitative deviations of the intestinal microbiota, such as a decrease in the number of major symbionts and an increase in the number of opportunistic pathogens, were observed in all examined patients with IBD. The obtained results showed that changes in SCFA concentrations in both nosologies of IBD differed significantly from those in the control group, which in combination with primary genetic defects of the barrier function of the epithelium and its regenerative ability can lead to deterioration in the course and prognosis of IBD. Evaluation of the ratio of SCFA fractions with the calculation of the anaerobic index may be useful for the diagnosis of intestinal dysbiosis in patients with IBD.

Background Primary immunodeficiency (PID), common variable immunodeficiency (CVID) are primary immunodeficiencies with disorder of the adaptive immune system, organ-specific pathology, as well as defects in the gut microbiome [1]. In patients with ulcerative colitis (UC) during relapse, similar changes. Methods The aim of the research is a comprehensive study of the structure of gut microbiota and mucosal protein profile (MPP) in patients with PID, CVID and UC in different phases of the disease course. The research included 19 patients with PID, 28 with CVID and 32 with UC (22 with relapse and 10 with persistent remission of the disease), control group - 20 healthy volunteers. Estimation of gut microbiota was performed by microbacteriological seeding faeces (MSF). Content of short-chain fatty acids (SCFA) in the feces as determined by gas-chromatography-mass spectrometry (GC-MS). Mucosal protein profile was based on isoelectric focusing techniques (SDS-PAGE, 2DGE). Mass spectrograms were obtained using MALDI-TOF-MS/MS (Bruker, USA). Molecular interaction and functional characteristics of proteins were studied using the STRING 10.0 databases. Results SCFA production showed a 6-, 9- and 11-fold decrease in propionic and butyric acids, mainly in patients with PID and UC: 0.2 + 0.1, 0.14 + 0.03 and 0.04 + 0.02, 0.08 + 0.02 mg/g, respectively (tab. 1). MSF showed a decrease in titers of E. coli, bifido- and lactobacilli on average 4.6 + 0.8 Lg. The conditionally pathogenic microbiota was represented by E. coli, hemolytic strains (n=34,104/g), Proteus spp. (n=48,105/g), Staphylococcus spp. (n=29,105–6/g), Candida alb. / glabrata (n=55,104–6/g) and Clostridium spp. (n = 38,104/g). Results of MPP (detection rate of 75% or more) of the colon mucosa in patients with PID and CVID were detected: 1, 2, 4 okkludin, kininogen 1, interleukin-1B, interleukin 8, B2-glycoprotein, heat shock protein 27, in patients with CVID - translational elongation factor, apolipoprotein C-III. In patients with UC - NF-kB, alipoprotein C-III, TNF-α, heat shock protein 27, interleukin-2 and 8 were presented. MPP patients with UC (stable remission phase): a-enolase, b-defensin-1, cathepsin D, prohibitin (tab. 2). Conclusion 1. In patients with PID, CVID and UC during relapse, markers of damage to the intestinal microbiome, a decrease in the production of SCFA and proteins characteristic of inflammation, apoptosis, proliferation, as well as proteins reflecting the activity of the autoimmune process, were identified. 2. During the period of drug remission in patients with UC, PID and CVID, specific components of altered MPP disappear, and a tendency towards restoration of the gut microbiota and SCFA production is recorded. References Jørgensen SF, Trøseid M, Kummen M, et al. Altered gut microbiota profile in common variable immunodeficiency associates with levels of lipopolysaccharide and markers of systemic immune activation. Mucosal Immunol. 2016; 9:1455-1465.

Gut microbiota imbalance is one of the major causes of ulcerative colitis (UC). L. rhamnosus SHA113 (LRS), a strain isolated from healthy human milk, influences the regulation of gut flora. This study aims to determine whether this strain can ameliorate UC by modulating gut microbiota. Mouse models of UC were established using C57BL/6Cnc mice with intragastric administration of 3.0% (w/v) dextran sodium sulfate (DSS). LRS was used to treat the mouse models of UC with 109 cfu mL-1 cell suspension via intragastric administration. To verify the effect of gut microbiota on UC, fecal microbiota collected from the mice after the treatment with LRS were also used to treat the UC mouse models (FMT). The severity of UC was evaluated based on body weight, colon length, disease activity index (DAI), and hematoxylin-eosin staining. The microbial composition was analyzed by 16S rRNA sequencing. The mRNA expression levels of cytokines, mucins, tight junction proteins, and antimicrobial peptides in the gastrointestinal tract were detected by quantitative real-time polymerase chain reaction. The short-chain fatty acid (SCFAs) in the cecal contents of all mice were quantitatively detected by gas chromatography and mass spectrometry. Both LRS and FMT exerted excellent therapeutic effects on UC, as evidenced by the reduction in body weight loss, colon length, and colon structural integrity, as well as the increase in the DAI (disease activity index). LRS and FMT treatments showed similar effects: (1) an increase of total SCFA production in the cecal contents and the abundance of gut microbial diversity and flora composition; (2) decreases in two genera (Parabacteroides and Escherichia/Shigella) related to the DAI and the enhancement of SCFAs and IL-10 positively related genera in the gut microbiota (Bilophila, Roseburia, Akkermansia, and Bifidobacterium); (3) downregulation of the expression of tumor necrosis factor-α, interleukin IL-6, and IL-1β, and upregulation of the expression of the anti-inflammatory cytokine IL-10; and (4) upregulation of the expression of mucins (Muc1-4) and tight junction protein ZO-1. Overall, L. rhamnosus SHA113 relieves UC via the regulation of gut microbiota: increases in SCFA-producing genera and decreases in UC-related genera. In addition, a single strain is sufficient to induce a significant change in the gut microbiota and exert therapeutic effects on UC.

Background There are few studies of the gut microbiome in new-onset IBD. We present a novel secondary bioinformatic re-analysis (BA) of sequence outputs mapped to latest microbial taxonomy derived from systematic review. Methods MEDLINE and Embase searches were performed for microbiome studies in pre-treatment IBD. Appraisal was completed with ROBINS-E. Available 16S rRNA sequence datasets were downloaded and missing datasets requested. Integrated datasets were run through a unified pipeline based in QIIME2 supplemented by phyloseq and DESeq2. Results From 12,264 studies, 10,804 abstracts and 217 full texts were screened. 31 studies were eligible; 18 met the requirements for BA. Most were low risk for bias, except uncontrolled confounding. Methodology varied extensively. Considering only amplicon data; samples originated from 1,743 unique individuals (including 678 Crohn’s disease (CD), 399 ulcerative colitis (UC), 123 ‘other’ IBD, 130 healthy, 405 symptomatic, and 8 familial controls) derived from 15 countries. DNA was extracted using 15 different kits, sequencing performed on 4 separate platforms targeting 10 different 16S rRNA hypervariable regions. There was a paucity of adult data, particularly mucosal biopsies. Bacterial alpha diversity was reduced: in faeces in paediatric UC vs symptomatic controls (SC), in adult CD and UC vs HC and in paediatric SC vs HC (Figure 1). In paediatric biopsies in CD vs SC, CD vs UC, SC vs UC (Figure 2). Beta-diversity BA by Bray-Curtis demonstrated clear distinctions between faecal and mucosal biopsy communities, least evident in UC. Faecal communities separated by geography, though less evidently in biopsies. Differential abundance analysis revealed enrichment of oral genera across sample types (Fusobacterium, Peptostreptococcus, Neisseria in CD; Haemophilus, Aggregatibacter, Peptostreptococcus, Porphyromonas, Neisseria, Gemella in UC). Short-chain fatty acid (SCFA) producers were diminished but less consistently across IBD phenotype and sample type. Conclusion This work demonstrates the utility of a combined systematic review/secondary data analysis approach to published microbiome datasets. Whilst synthesis remains challenging due to the methodological inconsistencies within these studies, this approach better accounts for these variations and presents a new way to consider this data. A reduction in bacterial diversity remains core to the IBD microbiome, though with more complexity than previously considered (SC<UC in paediatric biopsies). Microbial community structure changes by sample type and geography. Enrichment of oral bacteria is consistent across IBD subtypes and sample types suggesting their importance in the disease. A deficit in SCFA producers may also be important.

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.

Objective: Develop and evaluate mucoadhesive microspheres using Chitosan, Sodium alginate, and Sodium carboxymethyl cellulose (NaCMC) for sustained oral delivery of Metronidazole, aiming to improve bioavailability. Methods: Metronidazole-loaded microspheres were prepared via ionotropic gelation method with varying polymer ratios. Particle size, entrapment efficiency, swelling index, mucoadhesion (sheep mucosae), morphology (SEM), in-vitro wash-off test, drug release profile, and stability (6 months) were evaluated. Results: Chitosan content positively correlated with microsphere size. Entrapment efficiency ranged from 51.43% to 94.15%. Chitosan-based formulations, especially MTZ-7 (Chitosan:NaCMC, 3:1), displayed the highest mucoadhesion. SEM analysis revealed rough, spherical microspheres with a continuous polymeric coat. In-vitro wash-off test demonstrated prolonged residence time for Chitosan formulations. Sustained drug release was observed throughout the study, with MTZ-7 exhibiting the most desirable release profile. Stability studies showed no significant changes in drug release for selected formulations after 6 months. Conclusions: Chitosan-based microspheres, particularly MTZ-7, demonstrated superior mucoadhesive properties, sustained and controlled drug release, and desirable stability. These findings suggest the potential of Chitosan-based microspheres as a promising oral drug delivery system for Metronidazole, potentially addressing bioavailability concerns and improving therapeutic efficacy.

To study the interplay between butyrate concentration and butyrate-producing bacteria in fecal samples of ulcerative colitis (UC) patients vs control individuals. Fecal samples were collected from 14 control individuals (hemorrhoid patients only) and 26 UC patients (severe: n = 12, moderate: n = 6, remission: n = 8), recruited by the gastroenterologist at the Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India. Disease activity in UC patients was determined by clinical colitis activity index. We employed fluorescent in situ hybridization in combination with flow cytometry to enumerate the clostridium cluster population targeted by 16S rRNA gene probe. Major butyrate-producing species within this cluster were quantified to see if any change existed in control vs UC patients with different disease activity. This observed change was further validated by quantitative polymerase chain reaction. In addition to this, we carried out gas chromatography to evaluate the changes in concentration of major short chain fatty acids (SCFAs), namely acetate, n-butyrate, iso-butyrate, in the above samples. Student t test and Graph pad prism-6 were used to compare the data statistically. There was a significant decrease of Clostridium coccoides (control, 25.69% ± 1.62% vs severe, 9.8% ± 2.4%, P = 0.0001) and Clostridium leptum clusters (control, 13.74% ± 1.05% vs severe, 6.2% ± 1.8%, P = 0.0001) in fecal samples of UC patients. Furthermore, we demonstrated that some butyrate-producing members of the clostridial cluster, like Fecalibacterium prausnitzii (control, 11.66% ± 1.55% vs severe, 6.01% ± 1.6%, P = 0.0001) and Roseburia intestinalis (control, 14.48% ± 1.52% vs severe, 9% ± 1.83%, P = 0.02) were differentially present in patients with different disease activity. In addition, we also demonstrated decreased concentrations of fecal SCFAs, especially of n-butyrate (control, 24.32 ± 1.86 mmol/μL vs severe, 12.74 ± 2.75 mmol/μL, P = 0.003), iso-butyrate (control, 1.70 ± 0.41 mmol/μL vs severe, 0.68 ± 0.24 mmol/μL, P = 0.0441) and acetate (control, 39.51 ± 1.76 mmol/μL vs severe, 32.12 ± 2.95 mmol/μL, P = 0.047), in the fecal samples of UC patients. The observed decrease of predominant butyrate producers of clostridial clusters correlated with the reduced SCFA levels in active UC patients. This was further confirmed by the restoration in the population of some butyrate producers with simultaneous increase in the level of SCFA in remission samples. Our observations indicate that decreases in members of the clostridial cluster resulting in reduced butyrate levels contribute to the etiology of UC.

The gut microbiota in the human body is an important component that plays a pivotal role in the ability of the host to prevent diseases and recover from these diseases. If the human microbiome changes for any reason, it affects the overall functioning of the host. Healthy and vigorous gut microbiota require dietary fiber supplementation. Recently, oligosaccharides have been found to play a significant role in the modulation of microbiota. Several such oligosaccharides, i.e., xylooligosaccharides (XOS), mannooligosaccharides (MOS), and arabino-xylooligosaccharides (AXOS), are derived from hemicellulosic macromolecules such as xylan, mannan, and arabino-xylan, respectively. These oligosaccharides serve as substrates for the probiotic production of health-promoting substances (short-chain fatty acids, branched chain amino acids etc.), which confer a variety of health benefits, including the prevention of some dreaded diseases. Among hemicellulose-derived oligosaccharides (HDOs), XOS have been largely explored, whereas, studies on MOS and AXOS are currently underway. HDOs, upon ingestion, help reduce morbidities by lowering populations of harmful or pathogenic bacteria. The ATP-binding cassette (ABC) transporters are mainly utilized for the uptake of oligosaccharides in probiotics. Butyrate generated by the selective fermentation of oligosaccharides, along with other short-chain fatty acids, reduces gut inflammation. Overall, oligosaccharides derived from hemicelluloses show a similar potential as conventional prebiotics and can be supplemented as functional foods. This review summarizes the role of HDOs in the alleviation of autoimmune diseases (inflammatory bowel disease, Crohn's disease), diabetes, urinary tract infection, cardiovascular diseases, and antimicrobial resistance (AMR) through the modulation of the gut microbiota. The mechanism of oligosaccharide utilization and disease mitigation is also explained.

Background: Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is characterized by chronic relapsing intestinal inflammation driven by dysregulated immune responses and impaired epithelial barrier function. Increasing evidence highlights short-chain fatty acids (SCFAs)—particularly acetate, propionate, and butyrate—produced by gut microbiota as key mediators linking microbial composition to immune regulation and maintenance of intestinal homeostasis. Methodology: This review was conducted through an extensive analysis of clinical, experimental, and translational studies indexed in PubMed, Google Scholar, and the Cochrane Library, focusing on gut microbiota composition, SCFA metabolism, epithelial barrier integrity, immune mechanisms, and SCFA-targeted therapeutic strategies in IBD. Results: Patients with IBD consistently show reduced abundance of SCFA-producing bacteria, especially butyrate-generating taxa such as Faecalibacterium and Roseburia, accompanied by decreased fecal SCFA levels and impaired epithelial SCFA utilization. SCFAs exert potent anti-inflammatory effects via histone deacetylase inhibition and activation of SCFA-responsive G protein-coupled receptors, promoting regulatory immune phenotypes and suppressing pro-inflammatory signaling. Concurrently, they enhance intestinal barrier function by stimulating mucus production, reinforcing tight junctions, and supporting epithelial metabolic activity. Dietary fiber enrichment, prebiotics, probiotics, and microbiota-directed therapies demonstrate potential to restore SCFA availability and improve inflammatory and clinical outcomes, although responses remain heterogeneous. Conclusions: SCFAs represent a crucial interface between gut microbiota, immune regulation, and epithelial barrier integrity, positioning SCFA-related mechanisms as promising therapeutic targets in IBD. Despite encouraging evidence, further well-designed, mechanistic, and personalized studies are needed to clarify causality, optimize SCFA-based interventions, and translate findings into effective clinical strategies.

Background: Many literature studies have reported the beneficial effects of probiotics on human health, but few articles have evaluated their “real effects” on the modulation of microbiota after their use. Lactobacillus reuteri (L. reuteri) is one of the most studied probiotics with the best effects on gut microbiota. Aims: The primary aim of our study was the evaluation of the intestinal colonization by L. reuteri-LMG P 27481 and its effects on the modification of the gut bacterial flora. The secondary aim was the evaluation of side effects through the validated Gastrointestinal Symptom Rating Scale (GSRS). Patients and Methods: This is an interventional, open-label study conducted on 20 healthy adults (10 men and 10 women M/F; mean age 34 ±15 years) who received a probiotic Reuterin® LMG (L. reuteri LMG P 27481) for 28 consecutive days in drops at a concentration of 1 × 109 (five drops per day). Microbiota analysis was performed at enrollment (T0), at the end of probiotic supplementation (T1) and after a 14-day follow-up period (T2). Results: In our study we observed interesting quantitative and functional variations as regards the Firmicutes/Bacterioidetes ratio, intestinal permeability, and the production of short-chain fatty acids (SCFA). This probiotic was safe and was able to improve patients’ symptoms. Conclusions: The intake of L. reuteri LMG-P 27481 in healthy subjects showed transitory variations in some functional and metabolic gut functions, especially an improvement in the barrier effect and intestinal permeability, y and an increase in SCFA. Future studies should include target populations to have a greater range for modulation of the gut microbiota.

Intestinal mucosal barrier damage is regarded as the critical factor through which chronic unpredictable mild stress (CUMS) leads to a variety of physical and mental health problems. However, the exact mechanism by which CUMS induces intestinal mucosal barrier damage is unclear. In this study, 14, 28, and 42 d CUMS model mice were established. The indicators related to ileal mucosal barrier damage (IMBD), the composition of the ileal microbiota and its amino acid (AA) and short-chain fatty acid (SCFA) metabolic functions, and free amino acid (FAA) and SCFA levels in the ileal lumen were measured before and after each stress period. The correlations between them are analyzed to investigate how CUMS induces intestinal mucosal barrier damage in male C57BL/6 mice. With the progression of CUMS, butyric acid (BA) levels decreased (14 and 28 d) and then increased (42 d), and IMBD progressively increased. In the late CUMS stage (42 d), the degree of IMBD is most severe and positively correlated with significantly increased BA levels (p < 0.05) in the ileal lumen and negatively correlated with significantly decreased FAAs, such as aspartic, glutamic, alanine, and glycine levels (p < 0.05). In the ileal lumen, the abundance of BA-producing bacteria (Muribaculaceae, Ruminococcus, and Butyricicoccus) and the gene abundance of specific AA degradation and BA production pathways and their related enzymes are significantly increased (p < 0.05). In addition, there is a significant decrease (p < 0.05) in the abundance of core bacteria (Prevotella, Lactobacillus, Turicibacter, Blautia, and Barnesiella) that rely on these specific AAs for growth and/or are sensitive to BA. These changes, in turn, promote further colonization of BA-producing bacteria, exacerbating the over-accumulation of BA in the ileal lumen. These results were validated by ileal microbiota in vitro culture experiments. In summary, in the late CUMS stages, IMBD is related to an excessive accumulation of BA caused by dysbiosis of the ileal microbiota and its overactive AA degradation.