Tomomitsu Tahara

Complex interaction between host genetic and environmental factors has a role in Helicobacter pylori (H. pylori)-related gastric tumorigenesis, while invol

Exogenous lifestyle and environmental risk factors impact mutation burden in both benign and cancerous tissues. Moreover, interactions between the mucosa-associated microbiome and such genotoxic changes have been implicated in several cancer types. This study aimed to characterize the TP53 mutation spectrum in esophageal carcinoma (EC) with high amounts of Fusobacterium species. Quantitative PCR analysis of Pan-Fusobacterium species and Fusobacterium nucleatum was performed in 112 EC cases (89 squamous cell carcinomas [SCCs] and 23 adenocarcinomas). Results were correlated with TP53 mutation spectra and clinicopathological features. Both Pan-Fusobacterium species and F. nucleatum were significantly enriched in EC tissues compared with adjacent normal esophagus (both P < 0.001). The TP53 mutation spectrum in Pan-fusobacterium-high EC was characterized by a decrease in C: G→A: T and an increase in T: A→A: T substitutions (P < 0.001). Pan-fusobacterium-high EC was associated with male sex, tumors located in the upper or middle esophagus, and squamous cell histopathology. Cases of EC with detectable levels of Pan-Fusobacterium and F. nucleatum were also associated with more invasive tumors and more advanced cancer stages at diagnosis. These results suggest that EC with high numbers of Fusobacterium species was associated with a distinct mutation spectrum. Future studies should be conducted to investigate the mechanisms of how Fusobacterium species induce specific somatic mutations.

The risk of Helicobacter pylori (H. pylori)-related gastric tumorigenesis is closely associated with the degree of chronic gastritis, although other gastric mucosa microbes may be relevant in this process. The morphological identification of the gastric mucosa associated with the cancer-promoting microbiome may have important implications for gastric cancer prevention. This study characterized gastric mucosa microbiome communities in relation to their mucosal morphologies. A total of 94 biopsies from non-neoplastic gastric bodies underwent 16S rRNA sequencing. Microbiome structures were characterized in relation to their mucosal morphologies, which were obtained using narrow-band imaging with magnifying endoscopy. H. pylori infection- and inflammatory mucosa-associated gastric mucosal morphologies exhibited decreased bacterial alpha diversity measures and an increase in the abundance of the Helicobacter genus, while the mucosal morphology associated with severely atrophic mucosa exhibited increased bacterial alpha diversity measures and a decrease in the abundance of the Helicobacter genus. This type of mucosal morphology was also associated with increased levels of well-known gastric cancer-related bacteria, e.g., Streptococcus. The microbial dysbiosis associated with gastric mucosa morphology also correlated well with the occurrence of gastric cancer and the DNA methylation status. Our results suggest that gastric microbiome communities correlate well with their premalignant condition-associated mucosal morphologies.

Increasing evidence indicated substantial involvement of non-Helicobacter pylori microbiota in gastric tumorigenesis. We aimed to elucidate detailed relationship of microbiome dynamics between two different steps in gastric cancer (GC) such as cancer initiation and progression, and assessed their associations with clinicopathological and molecular changes. We systemically characterized gastric microbiome during GC initiation and progression using 944 biopsies from primary GC, non-cancerous gastric mucosa from both GC and non-cancer subjects. The association between specific microbial characteristics and GC risk, prognosis and molecular changes such as TP53 mutation, DNA methylation and telomere shortening were also evaluated. Microbial α-diversity in the gastric mucosa was decreased in relation to the GC occurrence, while it increased in primary GC tissue. Such paradoxical change was also observed in specific groups of bacteria during GC occurrence and its progression. GC risk-related microbiome was associated with differentiated GC, severe intestinal metaplasia, associated DNA methylation and telomere shortening, while GC tissue-specific microbiome was associated with more aggressive features of GC and TP53 mutation status. Our findings suggested the different role of non-Helicobacter pylori microbiota in GC initiation and progression steps.

Objective: Increasing evidence indicated substantial involvement of non-Helicobacter pylori microbiota in gastric tumorigenesis. We aimed to elucidate detailed relationship of microbiome dynamics between two different steps in gastric cancer (GC) such as cancer initiation and progression assessed their associations with clinicopathological and molecular changes. Methods: We systemically characterized gastric microbiome during GC development and progression using 944 biopsies from primary GC, non-cancerous gastric mucosa from both GC and non-cancer subjects. The association between specific microbial characteristics and GC risk, prognosis and molecular changes such as TP53 mutation, H. pylori- associated DNA methylation and telomere shortening were also evaluated. Results：Microbial α-diversity in the gastric mucosa was decreased in relation to the GC occurrence, while it increased in primary GC tissue. Such paradoxical change was also observed in specific groups of bacteria during GC occurrence and its progression. GC risk-related microbiome was associated with differentiated GC, severe intestinal metaplasia, H. pylori- associated DNA methylation and telomere shortening, while GC tissue-specific microbiome was associated with more aggressive features of GC and TP53 mutation status. Conclusions：Our findings suggested the different role of non-Helicobacter pylorimicrobiota in GC initiation and progression steps.

Background/Aims: Serum leucine-rich alpha-2 glycoprotein (LRG) is a potential biomarker of Crohn’s disease (CD). This study aimed to evaluate the usefulness of LRG in predicting clinical relapse in patients in remission with CD. Methods: This retrospective observational study assessed the relationships among patient-reported outcome (PRO2), LRG, and other blood markers. The influence of LRG on clinical relapse was assessed in patients in remission with CD. Results: Data of 94 patients tested for LRG between January 2021 and May 2023 were collected. LRG level did not correlate with PRO2 score (ρ = 0.06); however, it strongly correlated with C-reactive protein (CRP) level (r=0.79) and serum albumin level (r=–0.70). Among 69 patients in clinical remission, relapse occurred in 22 patients (31.9%). In the context of predicting relapse, LRG showed the highest area under the curve, followed by CRP level, platelet count, and albumin level. Multivariate analysis revealed that only LRG (P= 0.02) was an independent factor for predicting clinical remission. The cumulative non-relapse rate was significantly higher in patients with LRG < 13.8 μg/mL than in patients in remission with LRG ≥ 13.8 μg/mL and normal CRP level (P= 0.002) or normal albumin level (P= 0.001). Cumulative non-relapse rate was also higher in patients with LRG < 13.8 μg/mL compared to those with LRG ≥ 13.8 μg/mL in patients with L3 or B2+B3 of Montreal calcification. Conclusions: LRG is useful in predicting clinical relapse in patients with CD during biological remission. LRG is a useful biomarker for predicting prognosis, even in patients with intestinal stenosis, or previous/present fistulas.

Interaction between host genotoxic changes and mucosa-associated microbiome (MAM) dysbiosis may have a role in various digestive cancers. We investigated MAM in Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC) progression sequence and its association with host genotoxic changes. 16S rRNA gene sequencing was performed in three different groups of biopsies from nonneoplastic BE from patients without cancer (N, normal group; n = 47) and with EAC (ADJ, adjacent group; n = 27). Endoscopic biopsies were also obtained from EAC tissues (T, tumor group; n = 22). Results were correlated with TP53 mutation, telomere length and DNA methylation of candidate genes (N33, DPYS, SLC16A12, miR124A3 and miR34bc). Genome-wide DNA methylation examined by reduced representation bisulfite sequencing (RRBS) was available for 32 samples (n = 12 for N, n = 12 for ADJ and n = 22 for T groups). Lower microbial alpha diversity measures were observed in ADJ/T groups relative to N group and associated with higher mean Z score DNA methylation of candidate genes. Specific genera (n = 16) with significant change between ADJ/T groups relative to N group occurred mostly in ADJ group (13/16) and half of them (8/16) were associated with DNA methylation status. Integrated MAM and genome-wide methylation analysis demonstrated that hyper-methylated sites, associated with lower alpha diversity measures dominantly occurred within near the transcription start site, codifying genes were involved in metabolic processes. Our result shows that microbial dysbiosis in EAC mostly occurs in adjacent BE and such dysbiosis was associated with DNA methylation status, offering support for a pathogenic role of interaction between host genotoxic changes and MAM in this tumor type.

Aim: DNA methylation is associated with gastric cancer and Helicobacter pylori (H. pylori) infection, while increasing evidence indicated involvement of other microbes reside in gastric mucosa during gastric tumorigenesis. We investigated bacterial communities in the gastric mucosa accompanied with H. pylori related methylation anomaly.Materials & methods: Gastric mucosa samples from antrum were obtained from 182 cancer-free patients. Bacterial communities were evaluated using 16S rRNA sequencing. The result was correlated with H. pylori related promoter CpG island (CGI) methylation of five genes (IGF2, SLC16A12, SOX11, P2RX7 and MYOD1), LINE1 hypomethylation and telomere length.Results & conclusion: We showed correlation between lower bacterial alpha diversity and higher CGI methylation. Multivariate analysis demonstrated older age (t = 3.46, p = 0.0007), H. pylori infection (t = 9.99, p < 0.0001) and lower bacterial alfa diversity (Shannon index: t = -2.34, p = 0.02) were significantly associated with CGI hypermethylation. In genus or family levels, increased abundance of Helicobacter was associated with hyper CGI methylation with strongest correlation, while decreased abundance of four bacteria (Intrasporangiaceae family, Macellibacteroides, Peptostreptococcus and Dietziaceae family) was also associated with hyper CGI methylation. Our findings suggest the potential correlation between CGI methylation induction and lower bacterial alpha diversity in the gastric mucosa accompanied by H. pylori infection.

Change in mucosal microbiome is associated with various types of cancer in digestive tract. We hypothesized that microbial communities in the esophageal endoscopic wash fluids reflects resident flora in esophageal mucosa that is associated with esophageal carcinoma (EC) risk and/or directly correlates microbiome derived from EC tumor tissue. Studying microbial communities in esophageal endoscopic wash samples would be therefore useful to predict the incidence or risk of EC. We examined microbial communities of the endoscopic wash samples from 45 primary EC and 20 respective non-EC controls using 16S rRNA V3-V4 amplicon sequencing. The result was also compared with microbial communities in matched endoscopic biopsies from EC and non-cancerous esophageal mucosa. Compared with non-EC controls, 6 discriminative bacterial genera were detected in EC patients. Among them, relative abundance ratio of Prevotella and Shuttlewarthia, as well as decrease of genus Prevotella presented good prognostic performance to discriminate EC from controls (area under curve, 0.86, 0.82, respectively). Multivariate analysis showed occurrence of EC was an independent factor associated with decrease of this bacteria. Abundance of genus Prevotella in the esophageal endoscopic wash samples was significantly correlated with the abundance of this bacteria in the matched endoscopic biopsies from non-cancerous esophageal mucosa but not in the EC tissues. Our findings suggest that microbiome composition in the esophageal endoscopic wash samples reflects resident flora in the esophagus and significantly correlates with the incidence of EC.