Junichi Iwamoto

Background: Wild-type (WT) mice fed a conventional high-fat/high-sucrose diet (HFHSD) rarely develop metabolic dysfunction–associated steatohepatitis (MASH) with HCC. Because mouse bile acid (BA) is highly hydrophilic, we hypothesized that making it hydrophobic would lead to MASH with HCC. Methods: Eleven-week-old WT and Cyp2a12/Cyp2c70 double knockout (DKO) mice were divided into two groups, including one which was fed a normal chow diet, and one which was fed an HFHSD. Samples were collected after 15, 30, 47, and 58 weeks for histological, biochemical, and immunological analyses. Results: In the HFHSD group, body weight gain did not differ in WT versus DKO mice, although HFHSD-fed DKO mice exhibited markedly accelerated liver inflammation, fibrosis, and carcinogenesis. HFHSD upregulated lipogenesis and downregulated fatty acid oxidation in both WT and DKO mice, which increased liver lipid accumulation and lipotoxicity. However, the increase in reactive oxygen species production and carcinogenesis observed in DKO mice could not be explained by abnormal lipid metabolism alone. Regarding BA metabolism, DKO mice had a higher hydrophobicity index. They exhibited an age-associated increase in chenodeoxycholic acid (CDCA) levels because of CYP8B1 activity inhibition due to the farnesoid X receptor activation. HFHSD further downregulated CYP8B1, presumably by activating the Liver X receptor. Liver CDCA accumulation was associated with increased inflammation, reactive oxygen species production, and hepatocyte FGF15 induction. Moreover, in noncancerous liver tissues, HFHSD appeared to activate STAT3, an oncogenic transcription factor, which was enhanced by a CDCA-rich environment. Conclusions: Here, we developed a new model of MASH with HCC using mice with human-like BA composition and found that HFHSD and elevated hepatic CDCA synergistically increased the risk of MASH with HCC.

Dysbiosis in the intestinal microflora can affect the gut production of microbial metabolites, and toxic substances can disrupt the barrier function of the intestinal wall, leading to the development of various diseases. Decreased levels of Clostridium subcluster XIVa (XIVa) are associated with the intestinal dysbiosis found in inflammatory bowel disease (IBD) and Clostridium difficile infection (CDI). Since XIVa is a bacterial group responsible for the conversion of primary bile acids (BAs) to secondary BAs, the proportion of intestinal XIVa can be predicted by determining the ratio of deoxycholic acid (DCA)/[DCA + cholic acid (CA)] in feces orserum. For example, serum DCA/(DCA+CA) was significantly lower in IBD patients than in healthy controls, even in the remission period. These results suggest that a low proportion of intestinal XIVa in IBD patients might be a precondition for IBD onset but not a consequence of intestinal inflammation. Another report showed that a reduced serum DCA/(DCA + CA) ratio could predict susceptibility to CDI. Thus, the BA profile, particularly the ratio of secon dary to primary BAs, can serve as a surrogate marker of the intestinal dysbiosis caused by decreased XIVa.

Since intestinal secondary bile acids (BAs) prevent Clostridium difficile infection (CDI), the serum BA profile may be a convenient biomarker for CDI susceptibility in human subjects. To verify this hypothesis, we investigated blood samples from 71 patients of the Division of Gastroenterology and Hepatology at the time of admission (prior to antibiotic use and CDI onset). Twelve patients developed CDI during hospitalization, and the other 59 patients did not. The serum unconjugated deoxycholic acid (DCA)/[DCA + unconjugated cholic acid (CA)] ratio on admission was significantly lower in patients who developed CDI than in patients who did not develop CDI (p < 0.01) and in 46 healthy controls (p < 0.0001). Another unconjugated secondary BA ratio, 3β-hydroxy (3βOH)-BAs/(3βOH + 3αOH-BAs), was also significantly lower in patients who developed CDI than in healthy controls (p < 0.05) but was not significantly different between patients who developed and patients who did not develop CDI. A receiver operating characteristic (ROC) curve determined a cut-off point of DCA/(DCA + CA) < 0.349 that optimally discriminated on admission the high-risk patients who would develop CDI (sensitivity 91.7% and specificity 64.4%). In conclusion, a decreased serum DCA/(DCA + CA) ratio on admission strongly correlated with CDI onset during hospitalization in patients with gastrointestinal and hepatobiliary diseases. Serum BA composition could be a helpful biomarker for predicting susceptibility to CDI.

Western‐style high‐fat/high‐sucrose diet (HFHSD) changes gut microbiota and bile acid (BA) profiles. Because gut microbiota and BAs could influence each other, the mechanism of changes in both by HFHSD is complicated and remains unclear. We first aimed to clarify the roles of BAs in the HFHSD‐induced change of gut microbiota. Then, we studied the effects of the changed gut microbiota on BA composition and liver function. Male wild‐type (WT) and human‐like Cyp2a12/Cyp2c70 double knockout (DKO) mice derived from C57BL/6J were fed with normal chow or HFHSD for 4 weeks. Gut microbiomes were analyzed by fecal 16S ribosomal RNA gene sequencing, and BA composition was determined by liquid chromatography–tandem mass spectrometry. The DKO mice exhibited significantly reduced fecal BA concentration, lacked muricholic acids, and increased proportions of chenodeoxycholic and lithocholic acids. Despite the marked difference in the fecal BA composition, the profiles of gut microbiota in the two mouse models were quite similar. An HFHSD resulted in a significant increase in the BA pool and fecal BA excretion in WT mice but not in DKO mice. However, microbial composition in the two mouse models was drastically but similarly changed by the HFHSD. In addition, the HFHSD‐induced change of gut microbiota inhibited BA deconjugation and 7α‐dehydroxylation in both types of mice, which improved chronic liver injury observed in DKO mice. Conclusion: The HFHSD itself causes the change of gut microbiota due to HFHSD, and the altered composition or concentration of BAs by HFHSD is not the primary factor. On the contrary, the gut microbiota formed by HFHSD affects BA composition and ameliorates liver injury in the mouse model with human‐like hydrophobic BA composition.

Background/Aims: Crosstalk between the gut microbiota and bile acid plays an important role in the pathogenesis of gastrointestinal disorders. We investigated the relationship between microbial structure and bile acid metabolism in the ileal mucosa of Crohn’s disease (CD).Methods: Twelve non-CD controls and 38 CD patients in clinical remission were enrolled. Samples were collected from the distal ileum under balloon-assisted enteroscopy. Bile acid composition was analyzed by liquid chromatography-mass spectrometry. The gut microbiota was analyzed by 16S rRNA gene sequencing.Results: The Shannon evenness index was significantly lower in endoscopically active lesions than in non-CD controls. β-Diversity, evaluated by the UniFrac metric, revealed a significant difference between the active lesions and non-CD controls (P=0.039). The relative abundance of Escherichia was significantly higher and that of Faecalibacterium and Roseburia was significantly lower in CD samples than in non-CD controls. The increased abundance of Escherichia was more prominent in active lesions than in inactive lesions. The proportion of conjugated bile acids was significantly higher in CD patients than in non-CD controls, but there was no difference in the proportion of primary or secondary bile acids. The genera Escherichia and Lactobacillus were positively correlated with the proportion of conjugated bile acids. On the other hand, Roseburia, Intestinibacter, and Faecalibacterium were negatively correlated with the proportion of conjugated bile acids.Conclusions: Mucosa-associated dysbiosis and the alteration of bile acid composition were identified in the ileum of CD patients. These may play a role in the pathophysiology of ileal lesions in CD patients.

Non-steroidal anti-inflammatory drugs (NSAIDs) or low-dose aspirin (LDA) are the most common causes of drug-induced gastroduodenal ulcer and We investigated preventive treatment with use of concomitant anti-ulcer drugs and the clinical features of gastroduodenal ulcer in cases treated with these drugs. Patients with gastroduodenal ulcer and patients with bleeding were classified into 3 groups: LDA, non-aspirin NSAIDs, and those taking neither aspirin nor NSAIDs. Chronological changes over the past 16 years (1st-5th period) were investigated. The status of prevention of ulcer and clinical features were examined. From January 2002 to December 2018, the ratio of all patients taking NSAIDs and LDA increased significantly until 3rd period (p<0.05), but then started to decrease in 4th period; and the percentage of all patients taking NSAIDs and LDA decreased significantly (p<0.05) until 5th period. Among the 292 patients with gastroduodenal ulcer and the 121 patients with a bleeding ulcer taking NSAIDs and LDA, 16 (5.5%) and 9 (7.4%), respectively, were receiving preventive treatment with concomitant anti-ulcer drugs. The percentages of patients taking LDA and other antiplatelet drugs in patients with bleeding gastroduodenal ulcer were significantly higher than those in patients with non-bleeding. In conclusion, although the percentages of patients with gastroduodenal ulcer taking NSAIDs or LDA have not recently increased in real-world practice, preventive treatment in these patients is still low. This low rate of prevention suggests the need to enlighten physicians about preventive treatment because drug withdrawal of LDA has a high risk of cardiovasculr and cerebrovascular events.

Background and Aim: Non-steroidal anti-inflammatory drugs (NSAIDs) or low-dose aspirin (LDA) are the most common causes of drug-induced gastroduodenal ulcer. We investigated preventive treatment with use of concomitant anti-ulcer drugs and the clinical features of gastroduodenal ulcer in cases treated with these drugs.Method: A total of 2,332 patients with gastroduodenal ulcer and 241 patients with bleeding gastroduodenal ulcer were classified into 3 groups: those taking LDA, those taking non-aspirin NSAIDs (hereinafter referred to as NSAIDs), and those taking neither aspirin nor NSAIDs. Chronological changes in the percentage of each group and the change over the past 15 years were investigated. The status of prevention of ulcer and clinical features were examined in 264 patients with gastroduodenal ulcer taking NSAIDs or LDA, including 107 bleeding cases, in the past 8 years.Results: From January 2002 to December 2017, the percentage of all patients taking LDA increased until 2013, but from 2014, the percentage of patients taking LDA decreased in those with a bleeding ulcer. The percentage of patients taking NSAIDs decreased from 2002 in those with a bleeding ulcer. Among the 264 patients with gastroduodenal ulcer and the 107 patients with a bleeding ulcer taking NSAIDs and LDA, 16 (6%) and 9 (8%), respectively, were receiving preventive treatment with concomitant anti-ulcer drugs. The percentages of patients taking LDA and other antiplatelet drugs in patients with bleeding gastroduodenal ulcer were significantly higher than those in patients with non-bleeding. Conclusion: Although the percentages of patients with gastroduodenal ulcer taking NSAIDs or LDA have not recently increased in real-world practice, preventive treatment in these patients is still low. This low rate of prevention in cases of non-bleeding and bleeding gastroduodenal ulcer suggests the need to enlighten physicians about preventive treatment because drug withdrawal of LDA has a high risk of cardiovascular and cerebrovascular events

The agglutination titers of Brachyspira pilosicoli (B. pilosicoli) and Brachyspira aalborgi (B. aalborgi) were examined in colitis patients with human intestinal spirochetes. Among three cases of colitis patients, the titer of B. pilosicoli was extremely high in two cases while the titer of B. aalborgi was extremely high in one case. These three cases had symptoms of colitis, such as watery diarrhea, and we diagnosed the case as Brachyspira- related colitis. These findings suggest that the agglutination titers of Brachyspira may be useful in cases of Brachyspira- related colitis. Severe symptoms, such as abdominal pain and diarrhea, were observed in cases with high antibody titer of B. aalborgi, as well as B. pilosicoli, indicating that B. aalborgi could also cause symptomatic colitis.

Dysbiosis, especially a reduced Clostridium subcluster XIVa (XIVa), has been reported in several gastrointestinal diseases. Since XIVa is thought to be the main bacterial cluster that metabolizes bile acids (BAs) in the human intestine, we hypothesized that the BA profile in feces, and possibly in serum, could be a convenient biomarker for intestinal XIVa activity. First, blood and feces were collected from 26 healthy controls and 20 patients with gastrointestinal diseases, and the relationships among fecal microbiomes and fecal and serum BA compositions were studied. Second, serum BA compositions of 30 healthy controls and the remission and exacerbation states of 14 Crohn’s disease (CD) and 12 ulcerative colitis (UC) patients were compared. Fecal microbiomes were analyzed by terminal restriction fragment length polymorphism analysis, and BA compositions were quantified by HPLC-MS/MS. The highest positive correlation was observed between the fecal XIVa proportion and fecal unconjugated deoxycholic acid (DCA)/(DCA+unconjugated cholic acid [CA]) (r = 0.77, P < 0.0001) or serum DCA/(DCA+CA) (r = 0.52, P < 0.001). Diurnal variation in serum XIVa candidate markers also showed that DCA/(DCA+CA) was most stable and not affected by the contraction of the gallbladder. Serum DCA/(DCA+CA) was not significantly different between remission and exacerbation states in either CD or UC patients, but was significantly reduced in those in the remission state of CD and the remission and exacerbation states of UC compared with healthy controls (P < 0.05). Decreased XIVa exhibits a strong correlation with reduced intestinal BA metabolism. Fecal and serum DCA/(DCA+CA) could be useful surrogate markers for the intestinal proportion of XIVa.

A 66-year-old Japanese male with a history of Behçet disease exhibited oral and genital ulcers, and a round deep ileocecal ulcer. He was treated with a combination of mesalazine and 20 mg/day of prednisolone (PSL), but was only partially responsive to PSL and we were not able to reduce the steroid dosage. Adalimumab was also administered. However, the ulcer was not completely responsive, and weaning the patient off PSL remained impossible. In contrast, additional treatment with clarithromycin completely healed the refractory active ulcer and left only a scar. Furthermore, the ulcer has since maintained the scar stage despite successfully weaning the patient from PSL.