Efficacy of Tegoprazan in Patients With Functional Dyspepsia: A Prospective, Multicenter, Single-arm Study.

Background/Aims: Acid-suppressive drugs, such as proton pump inhibitors (PPIs), are treatment options for functional dyspepsia (FD). However, the efficacy of potassium-competitive acid blockers (P-CABs) in treating FD has not yet been established. This prospective multicenter clinical trial-based study aimed to assess the efficacy and safety of tegoprazan as a P-CAB treatment in patients with FD. Methods: FD was diagnosed using the Rome IV criteria. All patients received tegoprazan 50 mg once daily for 8 weeks. Dyspeptic symptoms were assessed using a dyspepsia symptom questionnaire (5-point Likert scale, Nepean Dyspepsia Index-Korean (NDI-K), and gastroesophageal reflux disease-health-related quality of life (GERD-HRQL). The main outcome was satisfactory symptom relief rates at 8 weeks. Results: In this study, from the initial screening of 209 patients, 173 were included in the per-protocol set analysis. Satisfactory symptom relief rates at 8 and 4 weeks were 86.7% and 74.6%, respectively. In addition, the NDI-K and GERD-HRQL scores significantly improved at 8 and 4 weeks compared with the baseline scores. The efficacy of tegoprazan was not influenced by the FD subtype or Helicobacter pylori status. In patients with overlapping FD and GERD, there was a greater improvement in the NDI-K and GERD-HRQL scores than in patients with FD symptoms only. No serious drug-related adverse events occurred during this study. Conclusion: Tegoprazan (50 mg) administered once daily provided satisfactory symptom relief for FD.

Sex Difference in the Effect of Bifidobacterium longum on Repeated Water Avoidance Stress-induced Gut Dysbiosis in Wistar Rats.

Dysbiosis in gut microbiota is known to contribute to development of irritable bowel syndrome. We tried to investigate the effect of Bifidobacterium longum on repeated water avoidance stress (WAS) in a Wistar rat model. The three groups (no-stress, WAS, and WAS with B. longum) of rats were allocated to sham or WAS for 1 hour daily for 10 days, and B. longum was administered through gavage for 10 days. Fecal pellet numbers were counted at the end of each 1-hour session of WAS. After 10 days of repeated WAS, the rats were eutanized, and the feces were collected. WAS increased fecal pellet output (FPO) significantly in both sexes (P < 0.001), while the female B. longum group showed significantly decreased FPO (P = 0.005). However, there was no consistent change of myeloperoxidase activity and mRNA expression of interleukin-1ß and TNF-α. Mast cell infiltration at colonic submucosa increased in the female WAS group (P = 0.016). In terms of fecal microbiota, the repeated WAS groups in both sexes showed different beta-diversity compared to control and WAS with B. longum groups. WAS-induced mast cell infiltration was reduced by the administration of B. longum in female rats. Moreover, administration of B. longum relieved WAS-caused dysbiosis, especially in female rats. In conclusion, B. longum was beneficial for WAS-induced stress in rats, especially in females.

The Effect of Clostridium butyricum on Gut Microbial Changes and Functional Profiles of Metabolism in High-fat Diet-fed Rats Depending on Age and Sex.

Background/Aims: A high-fat diet (HFD) causes dysbiosis and promotes inflammatory responses in the colon. This study aims to evaluate the effects of Clostridium butyricum on HFD-induced gut microbial changes in rats. Methods: Six-week-old Fischer-344 rats with both sexes were given a control or HFD during 8 weeks, and 1-to-100-fold diluted Clostridium butyricum were administered by gavage. Fecal microbiota analyses were conducted using 16S ribosomal RNA metagenomic sequencing and predictive functional profiling of microbial communities in metabolism. Results: A significant increase in Ruminococcaceae and Lachnospiraceae, which are butyric acid-producing bacterial families, was observed in the probiotics groups depending on sex. In contrast, Akkermansia muciniphila, which increased through a HFD regardless of sex, and decreased in the probiotics groups. A. muciniphila positively correlated with Claudin-1 expression in males (P < 0.001) and negatively correlated with the expression of Claudin-2 (P = 0.042), IL-1ß (P = 0.037), and IL-6 (P = 0.044) in females. In terms of functional analyses, a HFD decreased the relative abundances of M00131 (carbohydrate metabolism module), M00579, and M00608 (energy metabolism), and increased those of M00307 (carbohydrate metabolism), regardless of sex. However, these changes recovered especially in male C. butyricum groups. Furthermore, M00131, M00579, and M00608 showed a positive correlation and M00307 showed a negative correlation with the relative abundance of A. muciniphila (P < 0.001). Conclusion: The beneficial effects of C. butyricum on HFD-induced gut dysbiosis in young male rats originate from the functional profiles of carbohydrate and energy metabolism.

The Possible Preventative Role of Lactate- and Butyrate-Producing Bacteria in Colorectal Carcinogenesis.

Background/Aims: : The gut microbiome has emerged as a key player that mechanistically links various risk factors to colorectal cancer (CRC) etiology. However, the role of the gut microbiome in CRC pathogenesis remains unclear. This study aimed to characterize the gut microbiota in healthy controls (HCs) and patients with colorectal adenoma (AD) and CRC in subgroups based on sex and age. Methods: : Study participants who visited the hospital for surveillance of CRC or gastrointestinal symptoms were prospectively enrolled, and the gut microbiome was analyzed based on fecal samples. Results: : In terms of HC-AD-CRC sequence, commensal bacteria, including lactate-producing (Streptococcus salivarius) and butyrate-producing (Faecalibacterium prausnitzii, Anaerostipes hadrus, and Eubacterium hallii) bacteria, were more abundant in the HC group than in the AD and CRC groups. In the sex comparison, the female HC group had more lactate-producing bacteria (Bifidobacterium adolescentis, Bifidobacterium catenulatum, and Lactobacillus ruminis) than the male HC group. In age comparison, younger subjects had more butyrate-producing bacteria (Agathobaculum butyriciproducens and Blautia faecis) than the older subjects in the HC group. Interestingly, lactate-producing bacteria (B. catenulatum) were more abundant in females than males among younger HC group subjects. However, these sex- and age-dependent differences were not observed in the AD and CRC groups. Conclusions: : The gut microbiome, specifically lactate- and butyrate-producing bacteria, which were found to be abundant in the HC group, may play a role in preventing the progression of CRC. In particular, lactate-producing bacteria, which were found to be less abundant in healthy male controls may contribute to the higher incidence of CRC in males.

The Protective Effect of Roseburia faecis Against Repeated Water Avoidance Stress-induced Irritable Bowel Syndrome in a Wister Rat Model.

Roseburia faecis, a butyrate-producing, gram-positive anaerobic bacterium, was evaluated for its usefulness against repeated water avoidance stress (WAS)-induced irritable bowel syndrome (IBS) in a rat model, and the underlying mechanism was explored. We divided the subjects into three groups: one without stress exposure, another subjected to daily 1-hour WAS for 10 days, and a third exposed to the same WAS regimen while also receiving two different R. faecis strains (BBH024 or R22-12-24) via oral gavage for the same 10-day duration. Fecal pellet output (FPO), a toluidine blue assay for mast cell infiltration, and fecal microbiota analyses were conducted using 16S rRNA metagenomic sequencing. Predictive functional profiling of microbial communities in metabolism was also conducted. FPO and colonic mucosal mast cell counts were significantly higher in the WAS group than in the control group (male, P = 0.004; female, P = 0.027). The administration of both BBH024 (male, P = 0.015; female, P = 0.022) and R22-12-24 (male, P = 0.003; female, P = 0.040) significantly reduced FPO. Submucosal mast cell infiltration in the colon showed a similar pattern in males. In case of fecal microbiota, the WAS with R. faecis group showed increased abundance of the Roseburia genus compared to WAS alone. Moreover, the expression of a gene encoding a D-methionine transport system substrate-binding protein was significantly elevated in the WAS with R. faecis group compared to that in the WAS (male, P = 0.028; female, P = 0.025) group. These results indicate that R. faecis is a useful probiotic for treating IBS and colonic microinflammation.

Developing Operational Definitions Related to Helicobacter pylori Eradication Therapy.

BACKGROUND: The lack of well-established operational definitions is a major limitation of Helicobacter pylori eradication studies that use secondary databases. We aimed to develop and validate operational definitions related to H. pylori eradication therapy. METHODS: Operational definitions were developed by analyzing a nationwide H. pylori eradication registry and validated using real-world data from hospital medical records. The primary endpoint was the sensitivity of the operational definitions in identifying individuals who received H. pylori eradication therapy. The secondary endpoint was the sensitivity and specificity of the operational definition in identifying successful H. pylori eradication therapy. RESULTS: H. pylori eradication therapy was defined as a prescription for one of the following combinations: 1) proton pump inhibitor (PPI) + amoxicillin + clarithromycin, 2) PPI + amoxicillin + metronidazole, 3) PPI + metronidazole + tetracycline, 4) PPI + amoxicillin + levofloxacin, 5) PPI + amoxicillin + moxifloxacin, or 6) PPI + amoxicillin + rifabutin. In the validation set, the sensitivity of the operational definition for identifying individuals who received H. pylori eradication therapy was 99.7% and 99.8% for the first- and second-line therapies, respectively. Operational definition to determine success or failure of the H. pylori eradication therapy was developed based on a confirmatory test and the prescription of rescue therapy. The sensitivity and specificity of the operational definition for predicting successful eradication were 97.6% and 91.4%, respectively, in first-line therapy and 98.6% and 54.8%, respectively, in second-line therapy. CONCLUSION: We developed and validated operational definitions related to H. pylori eradication therapy. These definitions will help researchers perform various H. pylori eradication-related studies using secondary databases.

Comparison of a Polysaccharide Hemostatic Powder and Conventional Therapy for Peptic Ulcer Bleeding.

BACKGROUND & AIMS: Hemostatic powders have been clinically used in the treatment of gastrointestinal bleeding. We investigated the non-inferiority of a polysaccharide hemostatic powder (PHP), compared with conventional endoscopic treatments, for peptic ulcer bleeding (PUB). METHODS: This study was a prospective multi-center, randomized, open-label, controlled trial at 4 referral institutions. We consecutively enrolled patients who had undergone emergency endoscopy for PUB. The patients were randomly assigned to either a PHP or conventional treatment group. In the PHP group, diluted epinephrine was injected, and the powder was applied as a spray. Conventional endoscopic treatment included the use of electrical coagulation or hemoclipping after injection of diluted epinephrine. RESULTS: Between July 2017 and May 2021, 216 patients were enrolled in this study (PHP group, 105; control group, 111). Initial hemostasis was achieved in 92 of 105 patients (87.6%) in the PHP group and 96 of 111 patients (86.5%) in the conventional treatment group. Re-bleeding did not differ between the 2 groups. In subgroup analysis, the initial hemostasis failure rate in the conventional treatment group was 13.6% for Forrest IIa cases; however, there was no initial hemostasis failure in the PHP group (P = .023). Large ulcer size (≥15 mm) and chronic kidney disease with dialysis were independent risk factors for re-bleeding at 30 days. No adverse events were associated with PHP use. CONCLUSIONS: PHP is not inferior to conventional treatments and could be useful in initial endoscopic treatment for PUB. Further studies are needed to confirm the re-bleeding rate of PHP. CLINICALTRIALS: gov, Number: NCT02717416).

Anti-PD-L1 Antibody and/or 17ß-Estradiol Treatment Induces Changes in the Gut Microbiome in MC38 Colon Tumor Model.

PURPOSE: 17ß-Estradiol (E2) supplementation suppresses MC38 tumor growth by downregulating the expression of programmed death-ligand 1 (PD-L1). This study aims to figure out the gut microbiota that respond to anti-PD-L1 and/or estrogen treatment in MC38 colon cancer model. Materials and Methods: A syngeneic colon tumor model was developed by injection of MC38 cells into C57BL/6 background male and female mice. Three days before MC38 cells injection, E2 was supplemented to male mice daily for 1 week. Male and female mice with MC38 tumors (50-100 mm3) were injected with anti-PD-L1 antibody. Fresh feces were collected 26 days after injection of MC38 cells and 16S rRNA metagenomics sequencing of DNA extracted from feces was used to assess gut microbial composition. RESULTS: At the taxonomic family level, Muribaculaceae was enriched only in the MC38 male control group. In male mice, linear discriminant analysis effect size analysis at the species level revealed that the four microorganisms were commonly regulated in single and combination treatment with anti-PD-L1 and/or E2; a decrease in PAC001068_g_uc and PAC001070_s (family Muribaculaceae) and increase in PAC001716_s and PAC001785_s (family Ruminococcaceae). Interestingly, in the anti-PD-L1 plus E2 group, a decrease in opportunistic pathogens (Enterobacteriaceae group) and an increase in commensal bacteria (Lactobacillus murinus group and Parabacteroides goldsteinii) were observed. Furthermore, the abundance of Parabacteroides goldsteinii was increased in both males and females in the anti-PD-L1 group. CONCLUSION: Our results suggest that gut microbial changes induced by the pretreatment of estrogen before anti-PD-L1 might contribute to treatment of MC38 colon cancer.

Effect of Clostridium butyricum on High-Fat Diet-Induced Intestinal Inflammation and Production of Short-Chain Fatty Acids.

BACKGROUND/AIMS: A high-fat diet (HFD) can cause intestinal inflammation and alter the gut microbiota; probiotics, however, are known to have anti-inflammatory effects. This study aimed to investigate the response of rat colon to HFD and the effect of Clostridium butyricum on HFD-induced intestinal inflammation and production of short-chain fatty acids (SCFAs) according to sex. METHODS: Male and female 6-week-old Fischer-344 rats were fed a chow diet or HFD for 8 weeks, and Biovita or three different concentrations of C. butyricum were orally gavaged. The levels of tight junction proteins (TJPs), inflammatory markers in the ascending colonic mucosa, and bile acids (BAs) and SCFAs in stool were measured. RESULTS: HFD significantly increased the histological inflammation scores and fat proportions. Fecal BA levels were higher in the HFD group than in the control group, with a more prominent increase in deoxycholic acid/cholic acid after probiotics administration in females; however, no statistically significant differences were observed. TJPs showed an opposite response to HFD depending on sex, and tended to increase and decrease after HFD in males and females, respectively. The HFD-reduced TJPs were recovered by probiotics, with some statistical significance in females. HFD-decreased butyric acid in stools appeared to be recovered by probiotics in males, but not in females. The expression of inflammatory markers (TNF-α) was increased by HFD in males and decreased with medium-concentration probiotic supplementation. The opposite was observed in females. MPO was increased by HFD in both sexes and decreased by probiotic supplementation. CONCLUSIONS: The probiotic C. butyricum improved indicators of HFD-induced colonic inflammation such as levels of inflammatory markers and increased the production of SCFAs and the expression of TJPs. These effects tended to be more pronounced in male rats, showing sex difference.

Prevalence and trends of multiple antimicrobial resistance of Helicobacter pylori in one tertiary hospital for 20 years in Korea.

BACKGROUND: Failure of Helicobacter pylori (H. pylori) eradication is principally caused by antimicrobial resistance. Nowadays, multidrug resistance could be a major determinant of eradication failure. To assess minimal inhibitory concentration (MIC), antimicrobial resistance rates and trends in H. pylori isolated from patients with upper gastrointestinal disease with long-term period. MATERIALS AND METHODS: Patients who had H. pylori colonies isolated from culture were consecutively enrolled during the period of 2003-2022. From each patient, one to ten isolates were collected from culture of mucosal biopsy. MIC test was performed for amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, and moxifloxacin using agar dilution method. Trends in MIC distribution, prevalence of resistances with single and multiple were investigated which were suspected to be related to the failure of empirical H. pylori eradication treatment. RESULTS: From 2003 to 2022, a total of 873 patients were enrolled and 2735 H. pylori isolates were successfully collected. Increase in the primary resistance rate was found in clarithromycin (16.1%-31.0%, p = .022), metronidazole (30.6%-38.1%, p < 0.001), and both of levofloxacin and moxifloxacin (7.3%-35.7%, p < 0.001). The prevalence of multidrug resistance to both clarithromycin and metronidazole (9.2%-37.9%, p < 0.001), clarithromycin and fluoroquinolone (2.8%-41.7%, p < 0.001), and clarithromycin, metronidazole, and fluoroquinolone (1.4%-28.2%, p < 0.001) was found to significantly increase. CONCLUSIONS: The prevalence of multiple resistance against H. pylori in Korea is ongoing. Its trend should be considered when establishing an empirical treatment strategy (ClinicalTrials. gov: NCT05247112).

Changes in Gut Microbiome upon Orchiectomy and Testosterone Administration in AOM/DSS-Induced Colon Cancer Mouse Model.

PURPOSE: Sex hormones are known to affect the gut microbiota. Previously, we reported that endogenous and exogenous testosterone are associated with colorectal cancer (CRC) development and submucosal invasion. In the present study, we investigated whether the gut microbiota is affected by orchiectomy (ORX) and testosterone propionate (TP) administration using an azoxymethane/dextran sulfate sodium (AOM/DSS)-induced CRC mouse model. MATERIALS AND METHODS: Gut microbiota was evaluated by means of 16S rRNA gene sequencing of stool DNA extracted from feces that were obtained at 13 weeks after AOM injection (from 22-week-old animals) and stored in a gas-generating pouch. RESULTS: The increase in microbial diversity (Chao1 and Phylogenetic Diversity index) and Firmicutes/Bacteroidetes (F/B) ratio upon AOM/DSS treatment in ORX mice was significantly decreased by TP supplementation. The ratio of commensal bacteria to opportunistic pathogens was lower in the TP-administered females and ORX mice than in the AOM/DSS group. Opportunistic pathogens (Mucispirillum schaedleri or Akkermansia muciniphila) were identified only in the TP group. In addition, microbial diversity and F/B ratio were higher in male controls than in female and ORX controls. Flintibacter butyricus, Ruminococcus bromii, and Romboutsia timonensis showed similar changes in the male control group as those in the female and ORX controls. CONCLUSION: In conclusion, testosterone determines the dysbiosis of gut microbiota, which suggests that it plays a role in the sex-related differences in colorectal carcinogenesis.

Erratum: The Protective Effect of Roseburia faecis Against Repeated Water Avoidance Stress-induced Irritable Bowel Syndrome in a Wister Rat Model.

[This corrects the article on p. 93 in vol. 28, PMID: 37830115.].

Stereotactic body radiotherapy versus radiofrequency ablation as initial treatment of small hepatocellular carcinoma.

BACKGROUND/AIM: Stereotactic body radiotherapy (SBRT) may be an alternative treatment for patients with small (≤3 cm) hepatocellular carcinomas (HCCs) who were not indicated for resection or local ablation therapy. This study compared the therapeutic effects of radiofrequency ablation (RFA) and SBRT in patients with small (≤3 cm) HCCs. METHODS: Data of HCC patients who underwent SBRT or RFA as an initial treatment at four tertiary referral hospitals between March 2011 and February 2017 were reviewed. The patient inclusion criteria were a single nodule measuring ≤3 cm in size and not suitable for resection. RESULTS: SBRT and RFA were performed for 72 (SBRT group) and 134 (RFA group) patients, respectively. The 1-, 3-, and 5-year overall survival (OS) rates were 97.0%, 80.3%, and 80.3%, respectively, in the SBRT group compared with 98.5%, 83.9%, and 80.8%, respectively, in the RFA group, with no significant differences between the groups (P = 0.81). The estimated five-year local control (LC) rate was 68.1% in the SBRT group and 73.1% in the RFA group (P = 0.81). In the SBRT group analysis, both SBRT alone (n = 34) and SBRT combined with transarterial chemoembolization (n = 38) showed no difference with RFA in OS (P = 0.72 and P = 0.90) or LC rate (P = 0.95 and P = 0.68), respectively. CONCLUSION: SBRT is an effective and safe treatment method for small HCCs, with survival and tumor recurrence rates similar to those of RFA.

Combination treatment with 17ß-estradiol and anti-PD-L1 suppresses MC38 tumor growth by reducing PD-L1 expression and enhancing M1 macrophage population in MC38 colon tumor model.

17ß-estradiol (E2) is known to have a protective effect in colorectal cancer (CRC); thus, E2 may be effective for cancer immunotherapy in CRC. The aim of this study is to evaluate the effect of combination therapy with E2 and anti-programmed cell death receptor-1 ligand (PD-L1) antibodies, and the effects of sex and estrogen on colon tumor growth, PD-L1 expression, and tumor-associated cell populations in an MC38 colon tumor model. Male mice showed increased MC38 colon tumor growth and PD-L1 expression in tumor sections as well as higher proportion of cancer-associated fibroblasts (CD45-CD31-CD140a+), PD-L1-expressing tumor cells (CD45-CD274+) and tumor-associated macrophages (TAMs) (CD11b+F4/80+CD274+) compared to female mice. E2 treatment prior to MC38 injection significantly reduced these phenomena in male mice. Furthermore, co-treatment with E2 and anti-PD-L1 antibodies significantly inhibited MC38 tumor growth and reduced PD-L1-expressing cells in male mice compared to treatment with either E2 or anti-PD-L1 antibodies alone. Combination treatment with E2 and anti-PD-L1 decreased TAM population (CD11b+F4/80+) in the tumor mass while increasing M1 TMAs (CD11b+F4/80+CD86+). These results suggest that estrogen inhibits MC38 tumor growth by downregulating PD-L1 expression and regulating tumor-associated cell populations. Furthermore, estrogen boosted the effect of anti-PD-L1 antibody in the MC38 tumor model.

Evaluation of Real-Time Endogenous Brain-Computer Interface Developed Using Ear-Electroencephalography.

While previous studies have demonstrated the feasibility of using ear-electroencephalography (ear-EEG) for the development of brain-computer interfaces (BCIs), most of them have been performed using exogenous paradigms in offline environments. To verify the reliable feasibility of constructing ear-EEG-based BCIs, the feasibility of using ear-EEG should be further demonstrated using another BCI paradigm, namely the endogenous paradigm, in real-time online environments. Exogenous and endogenous BCIs are to use the EEG evoked by external stimuli and induced by self-modulation, respectively. In this study, we investigated whether an endogenous ear-EEG-based BCI with reasonable performance can be implemented in online environments that mimic real-world scenarios. To this end, we used three different mental tasks, i.e., mental arithmetic, word association, and mental singing, and performed BCI experiments with fourteen subjects on three different days to investigate not only the reliability of a real-time endogenous ear-EEG-based BCI, but also its test-retest reliability. The mean online classification accuracy was almost 70%, which was equivalent to a marginal accuracy for a practical two-class BCI (70%), demonstrating the feasibility of using ear-EEG for the development of real-time endogenous BCIs, but further studies should follow to improve its performance enough to be used for practical ear-EEG-based BCI applications.

[Chicago Classification ver. 4.0: Diagnosis of Peristaltic Disorder].

The Chicago Classification is being revised continuously for the accurate diagnosis of esophageal peristaltic disorders in which the etiology is unclear, and the disease behavior is heterogeneous. The ver. 4.0 was recently updated. A representative change in the diagnosis of esophageal peristaltic disorders of the ver. 4.0 showed that the distinction between major and minor disorders was eliminated and was divided into the following four diagnoses: absent contractility, distal esophageal spasm (DES), hypercontractile esophagus (HE), and ineffective esophageal motility. Compared to the ver. 3.0, it recommended a more detailed protocol of high-resolution esophageal manometry and methods of interpreting manometric. In addition, it emphasized the clinically relevant symptoms in diagnosing DES and HE, and presented provocative tests (e.g., multiple rapid swallow and rapid drinking challenge), as well as additional testing, including impedance, timed barium esophagogram and functional lumen imaging probe, which may provide more standardized and rigorous criteria for peristaltic patterns and to minimize the ambiguity in diagnosis. Although it will take time and effort to apply this revised Chicago Classification in clinical practice, it may help diagnose and manage patients with esophageal peristalsis disorder in the future.

Physiological activity of E. coli engineered to produce butyric acid.

Faecalibacterium prausnitzii (F. prausnitzii) is one of the most abundant bacteria in the human intestine, with its anti-inflammatory effects establishing it as a major effector in human intestinal health. However, its extreme sensitivity to oxygen makes its cultivation and physiological study difficult. F. prausnitzii produces butyric acid, which is beneficial to human gut health. Butyric acid is a short-chain fatty acid (SCFA) produced by the fermentation of carbohydrates, such as dietary fibre in the large bowel. The genes encoding butyryl-CoA dehydrogenase (BCD) and butyryl-CoA:acetate CoA transferase (BUT) in F. prausnitzii were cloned and expressed in E. coli to determine the effect of butyric acid production on intestinal health using DSS-induced colitis model mice. The results from the E. coli Nissle 1917 strain, expressing BCD, BUT, or both, showed that BCD was essential, while BUT was dispensable for producing butyric acid. The effects of different carbon sources, such as glucose, N-acetylglucosamine (NAG), N-acetylgalactosamine (NAGA), and inulin, were compared with results showing that the optimal carbon sources for butyric acid production were NAG, a major component of mucin in the human intestine, and glucose. Furthermore, the anti-inflammatory effects of butyric acid production were tested by administering these strains to DSS-induced colitis model mice. The oral administration of the E. coli Nissle 1917 strain, carrying the expression vector for BCD and BUT (EcN-BCD-BUT), was found to prevent DSS-induced damage. Introduction of the BCD expression vector into E. coli Nissle 1917 led to increased butyric acid production, which improved the strain's health-beneficial effects.