Gut microbiota signatures in tissues of the colorectal polyp and normal colorectal mucosa, and faeces

To explore the potential combined treatment strategy for colorectal cancer: Inhibition of cancer stem cells and enhancement of intestinal immune microenvironment

BACKGROUND

The antibiotic salinomycin, a well-known cancer stem cell inhibitor, may impact the diversity of the intestinal microbiota in colorectal cancer (CRC) mice, which plays a pivotal role in shaping the immune system. This study explores the anti-cancer effects and mechanisms of combining salinomycin and fecal microbiota transplantation (FMT) in treating CRC.

METHODS

FMT was given via enema, while salinomycin was injected intraperitoneally into the CRC mouse model induced by azoxymethane/dextran sodium sulfate.

RESULTS

In CRC mice, a large number of LGR5-labeled cancer stem cells and severe disturbances in the intestinal microbiota were observed. Interestingly, salinomycin inhibited the proliferation of cancer stem cells without exacerbating the microbial disorder as expected. In comparison to salinomycin treatment, the combination of salinomycin and FMT significantly improved pathological damage and restored intestinal microbial diversity, which is responsible for shaping the anti-cancer immune microenvironment. The supplementation of FMT significantly increased the levels of propionic acid and butyric acid while also promoting the infiltration of CD8+ T cells and Ly6G+ neutrophils, as well as reducing F4/80+ macrophage recruitment. Notably, cytokines that were not impacted by salinomycin exhibited robust reactions to alterations in the gut microbiota. These included pro-inflammatory factors (IL6, IL12b, IL17, and IL22), chemokine-like protein OPN, and immunosuppressive factor PD-L1.

CONCLUSIONS

Salinomycin plays the role of "eliminating pathogenic qi," targeting cancer stem cells; FMT plays the role of "strengthening vital qi," reversing the intestinal microbiota disorder and enhancing anti-cancer immunity. They have a synergistic effect on the development of CRC.

Microbiome analysis of gut microbiota in patients with colorectal polyps and healthy individuals

Colorectal polyps serve as the primary precursors for colorectal cancer. A close relationship has been observed between colorectal polyps and gut microbiota. However, the composition and role of the microbiome associated with tubular adenoma are not well understood. In this study, we prospectively evaluated alterations in gut microbiota among patients with colorectal polyps. A total of 60 subjects were enrolled in this study, including 30 patients with colorectal polyps (CP group) and 30 healthy controls (control group). The 16S rRNA sequencing was employed to characterize the gut microbiome in fecal samples. The results revealed that the beta diversity of the gut microbiota in the CP group significantly differs from that of the control group (p = 0.001). At the phylum level, the relative abundance of Bacteroides, Fusobacteria, and Proteobacteria was higher in the CP group compared to the control group (p < 0.05), whereas the relative abundance of Actinobacteria was higher in the control group in comparison to the CP group (p < 0.05). At the genus level, the abundance of Bacteroides increased in the CP group (p < 0.05), while Bifidobacterium declined in the CP group (p < 0.05). At the species level, the abundance of Clostridium perfringens, unidentified_Bacteroides, unidentified_Dorea, Escherichia coli, Clostridium ramosum, and Ruminococcus gnavus was higher (p < 0.05), whereas the abundance of Bifidobacterium adolescentis, unclassified_Bifidobacterium, Bifidobacterium longum, Faecalibacterium prausnitzii, and unidentified_Bifidobacterium is lower in CP group compared to the control group (p < 0.05). There was a structural imbalance in the composition of intestinal colonization flora for CP patients, characterized by a decrease in beneficial bacteria and an increase in harmful bacteria. Escherichia, Shigella, and Bacteroides may serve as promising biomarkers for early detection of colorectal polyps.

Long-read 16S rRNA amplicon sequencing reveals microbial characteristics in patients with colorectal adenomas and carcinoma lesions in Egypt

BACKGROUND

Colorectal cancer (CRC) is among the five leading causes of cancer incidence and mortality. During the past decade, the role of the gut microbiota and its dysbiosis in colorectal tumorigenesis has been emphasized. Metagenomics and amplicon-based microbiome profiling provided insights into the potential role of microbial dysbiosis in the development of CRC.

AIM

To address the scarcity of information on differential microbiome composition of tumor tissue in comparison to adenomas and the lack of such data from Egyptian patients with CRC.

MATERIALS AND METHODS

Long-read nanopore sequencing of 16S rRNA amplicons was used to profile the colonic microbiota from fresh colonoscopic biopsy samples of Egyptian patients with CRC and patients with colonic polyps.

RESULTS

Species richness of CRC lesions was significantly higher than that in colonic polyps (p-value = 0.0078), while evenness of the CRC group was significantly lower than the colonic polyps group (p-value = 0.0055). Both species richness and Shannon diversity index of the late onset CRC samples were significantly higher than those of the early onset ones. The Firmicutes-to-Bacteroidetes (F/B) ratio was significantly higher in the CRC group than in the colonic polyps group (p-value = 0.0054), and significantly higher in samples from early-onset CRC. The Enterococcus spp. were significantly overabundant in patients with rectal cancer and early-onset CRC, while Staphylococcus spp. were significantly higher in patients with sigmoid cancer and late-onset CRC. In addition, the relative abundance of Fusobacterium nucleatum was significantly higher in CRC patients.

CONCLUSION

Differentiating trends were identified at phylum, genus, and species levels, despite the inter-individual differences. In summary, this study addressed the microbial dysbiosis associated with CRC and colonic polyps groups, paving the way for a better understanding of the pathogenesis of early and late-onset CRC in Egyptian patients.

Polygonatum kingianum polysaccharide alleviated intestinal injuries by mediating antioxidant ability and microbiota

Introduction

Polygonatum kingianum is a well-known medicinal herb with proven bioactivities; however, little is known about the effects of its polysaccharide on intestinal injuries in animals induced by lipopolysaccharide (LPS).

Methods

A total of 30 Institute of Cancer Research (ICR) mice were divided into control (CH), induced (MH), and treated (H) groups. Mice in group H were supplemented with 100 mg/kg Polygonatum kingianum polysaccharides, while groups C and M were treated with the same amount of normal saline by gavage for 18 days. On the 18th day animals in groups M and H were induced by LPS (10 mg/kg).

Results

The results showed the weight of mice in group MH significantly dropped (P < 0.0001), while mice in the PK group had a higher weight (P < 0.01). Pathological analysis found that the majority of the villi in mice induced by LPS were broken and short, while PK-treated animals had longer and considerably integrated villi. The villi length in groups CH (P < 0.0001) and H (P < 0.0001) was longer than that in group M, and the value of villi length/crypt depth in group MH was smaller than that in groups CH (P < 0.0001) and H (P < 0.0001), while the crypt depth in group MH was higher than in groups CH (P < 0.0001) and H (P < 0.0001). Serum inspection showed that MAD (P < 0.05), IL-1β (P < 0.05), IL-6 (P < 0.05), and TNF-α (P < 0.01) were significantly higher in group MH, while SOD (P < 0.001), T-AOC (P < 0.01), and GSH-Px (P < 0.01) were notably higher in groups CH and H. Microbiome sequencing of mice obtained 844,477 raw and 725,469 filtered reads. There were 2,407 ASVs detected in animals, and there were 312 and 328 shared ASVs between CH and MH, and CH and H, respectively. There were 5 phyla and 20genera of remarkable bacteria found among mice groups including genera of Escherichia, Pseudomonas_E, Mailhella, Paramuribaculum, NM07-P-09, Odoribacter, Nanosyncoccus, SFM01, Onthenecus, Clostridium_Q, UBA6985, Ructibacterium, UBA946, Lachnoclostridium_B, Evtepia, CAG-269, Limivicinus, Formimonas, Dehalobacterium, Dwaynesavagella, and UBA6985. We revealed that Polygonatum kingianum polysaccharide could alleviate intestinal injuries by promoting oxidation resistance, decreasing inflammatory responses, and accommodating the intestinal microbiota of mice.

Discussion

Our results suggest the possibility of developing novel therapies for intestinal diseases.

Interaction of human gut microbiota and local immune system in progression of colorectal adenoma (MIMICA-1): a protocol for a prospective, observational cohort study

INTRODUCTION

The current understanding of colorectal carcinogenesis is based on the adenoma-carcinoma sequence, where genetics, intestinal microbiota changes and local immunity shifts seem to play the key roles. Despite the emerging evidence of dysbiotic intestinal state and immune-cell infiltration changes in patients with colorectal adenocarcinoma, early and advanced adenoma as precursors of colorectal cancer, and carcinoma in situ as the following progression, are rather less studied. The newly colon-site adapted AI-based analysis of immune infiltrates is able to predict long-term outcomes of colon carcinoma. Though it could also facilitate the pathologic evaluation of precancerous lesion's potential to progress. Therefore, the purpose of this prospective cohort study (MIMICA-1) is, firstly, to identify the intestinal microbiota and immune infiltration patterns around the normal bowel tissue, early and advanced adenoma, carcinoma in situ, and adenocarcinoma, and secondly, to analyze the immune - microbiome interplay along the steps of conventional colorectal tumorigenesis.

METHODS AND ANALYSES

This study aims to prospectively recruit 40 patients (10 per group) with confirmed colorectal dysplasia undergoing endoscopic polypectomy, endoscopic mucosal resection for colorectal small (≤1cm), and large (>1cm) adenoma or carcinoma in situ, or biopsy and subsequent colon resection for invasive colorectal cancer, and 10 healthy patients undergoing screening colonoscopy. Stool samples will be collected prior to bowel preparation for the analysis of fecal (luminal) microbiota composition. Biopsy specimens will be taken from the terminal ileum, right colon, left colon, and a pathological lesion in the colon (if present) to assess mucosa-associated microbiota composition and intestinal immunity response. DNA will be extracted from all samples and sequenced using the Illumina MiSeq platform. Unifrac and Bray-Curtis methods will be used to assess microbial diversity. The intestinal immune system response will be examined using digital image analysis where primarily immunohistochemistry procedures for CD3, CD8, CD20 and CD68 immune cell markers will be performed. Thereafter, the count, density and distribution of immunocompetent cells in epithelial and stromal tissue compartments will be evaluated using AI-based platform. The interaction between the microbial shifts and intestinal immune system response in adenoma-carcinoma sequence and the healthy patients will be examined. In addition, fecal samples will be explored for gut microbiota's composition, comparing fecal- and tissue-derived bacterial patterns in healthy gut and along the adenoma-carcinoma sequence.

DISCUSSION

We hypothesize that changes within the human gut microbiota led to detectable alterations of the local immune response and correlate with the progression from normal mucosa to colorectal adenoma and invasive carcinoma. It is expectable to find more severe gut immune infiltration at dysplasia site, though analyzing invasive colorectal cancer we expect to detect broader mucosa-associated and luminal microbiota changes with subsequent local immune response at near-lesion site and possibly throughout the entire colon. We believe that specific compositional differences detected around premalignant colorectal lesions are critically important for its primary role in initiation and acceleration of colorectal carcinogenesis. Thus, these microbial patterns could potentially supplement fecal immunohistochemical tests for the early non-invasive detection of colorectal adenoma. Moreover, AI-based analysis of immune infiltrates could become additional diagnostic and prognostic tool in precancerous lesions prior to the development of colorectal cancer.

REGISTRATION

The study is registered at the Australian New Zealand Clinical Trials Registry (ACTRN12624000976583) https://www.anzctr.org.au/.

Dissecting the causal links between gut microbiome, immune traits and polyp using genetic evidence

Background

Previous research has demonstrated an association between gut microbiota and immune status with the development of several diseases. However, whether these factors contribute to polyps remains unclear. This study aims to use Mendelian randomization (MR) to investigate the causal relationship between gut microbiota and 4 types of polyps (nasal, gallbladder, colon, and gastric polyps), as well as to analyze the mediating role of immune traits.

Methods

This study utilized large-scale GWAS meta-analyses of gut microbiota (MiBioGen Consortium), 731 immune traits, and 4 types of polyps (one from the FinnGen Consortium and three from the NBDC Human Database). Univariate MR with the inverse variance weighted (IVW) estimation method was employed as the primary analytical approach. A two-step MR analysis was performed to identify potential mediating immune traits. Additionally, multivariable MR approach based on Bayesian model averaging (MR-BMA) was employed to further prioritize gut microbiota and immune traits associated with polyp development.

Results

Based on IVW method in univariate MR analysis, we identified 39 gut microbial taxa and 135 immune traits significantly causally associated with at least one type of polyp. For nasal polyps, 13 microbial taxa and 61 immune traits were causally associated. After false discovery rate (FDR) correction, CD3 on Central Memory CD8+ T cells and CD3 on CD4 regulatory T cells remained significant. MR-BMA identified 4 gut microbial taxa and 4 immune traits as high priority. For gallbladder polyps, 9 microbial taxa and 30 immune traits were causally associated. MR-BMA identified 8 microbial taxa and 6 immune traits as higher importance. For colon polyps, 6 microbial taxa and 21 immune traits were causally associated. MR-BMA identified 4 microbial taxa and 3 immune traits as higher importance. For gastric polyps, 12 microbial taxa and 33 immune traits were causally associated. Actinobacteria remained significant after FDR correction, and MR-BMA identified 7 gut microbial taxa and 6 immune traits as high priority. We identified 16 causal pathways with mediator directions consistent with the direction of gut microbiome-polyp association. Of these, 6 pathways were associated with the mechanism of nasal polyps, 1 with gallbladder polyps, 2 with colon polyps, and 7 with gastric polyps.

Conclusions

Our findings shed light on the causal relationships between gut microbiota, immune traits, and polyp development, underscoring the crucial roles of gut microbiota and immune status in polypogenesis. Furthermore, these findings suggest potential applications in polyp prevention, early screening, and the development of effective strategies to reduce polyp risk.

Individuality and generality of intratumoral microbiome in the three most prevalent gynecological malignancies: an observational study

Growing evidence have indicated the crucial role of intratumor microbiome in a variety of solid tumor. However, the intratumoral microbiome in gynecological malignancies is largely unknown. In the present study, a total of 90 Han patients, including 30 patients with cancer in cervix, ovary, and endometrium each were enrolled, the composition of intratumoral microbiome was assessed by 16S rDNA amplicon high throughput sequencing. We found that the diversity and metabolic potential of intratumoral microbiome in all three cancer types were very similar. Furthermore, all three cancer types shared a few taxa that collectively take up high relative abundance and positive rate, including Pseudomonas sp., Comamonadaceae gen. sp., Bradyrhizobium sp., Saccharomonospora sp., Cutibacterium acnes, Rubrobacter sp., Dialister micraerophilus, and Escherichia coli. Additionally, Haemophilus parainfluenzae and Paracoccus sp. in cervical cancer, Pelomonas sp. in ovarian cancer, and Enterococcus faecalis in endometrial cancer were identified by LDA to be a representative bacterial strain. In addition, in cervical cancer patients, alpha-fetoprotein (AFP) (correlation coefficient = -0.3714) was negatively correlated (r = 0.4, 95% CI: 0.03 to 0.7) with Rubrobacter sp. and CA199 (correlation coefficient = 0.3955) was positively associated (r = 0.4, 95% CI: 0.03 to 0.7) with Saccharomonospora sp.. In ovarian cancer patients, CA125 (correlation coefficient = -0.4451) was negatively correlated (r = -0.4, 95% CI: -0.7 to -0.09) with Porphyromonas sp.. In endometrial cancer patients, CEA (correlation coefficient = -0.3868) was negatively correlated (r = -0.4, 95% CI: -0.7 to -0.02) with Cutibacterium acnes. This study promoted our understanding of the intratumoral microbiome in gynecological malignancies.IMPORTANCEIn this study, we found the compositional spectrum of tumor microbes among gynecological malignancies were largely similar by sharing a few taxa and differentiated by substantial species owned uniquely. Certain species, mostly unreported, were identified to be associated with clinical characteristics. This study prompted our understanding of gynecological malignancies and offered evidence for tumor microbes affecting tumor biology among cancers in the female reproductive system.

Gut Microbiota Signatures in Colorectal Cancer as a Potential Diagnostic Biomarker in the Future: A Systematic Review

The gut microbiota has acquired significant attention in recent years for its potential as a diagnostic biomarker for colorectal cancer (CRC). In this literature review, we looked at the studies exploring alterations in gut microbiota composition associated with CRC, the potential mechanisms linking gut dysbiosis to CRC development, and the diagnostic approaches utilizing gut microbiota analysis. Our research has led to the conclusion that individuals with CRC often display alterations in their gut microbiota composition compared to healthy individuals. These alterations can include changes in the diversity, abundance, and type of bacteria present in the gut. While the use of gut microbiota as a diagnostic biomarker for CRC holds promise, further research is needed to validate its effectiveness and standardize testing protocols. Additionally, considerations such as variability in the microbiota composition among individuals and potential factors must be addressed before microbiota-based tests can be widely implemented in clinical practice.

Gut microbes on the risk of advanced adenomas

BACKGROUND

More than 90% of colorectal cancer (CRC) arises from advanced adenomas (AA) and gut microbes are closely associated with the initiation and progression of both AA and CRC.

OBJECTIVE

To analyze the characteristic microbes in AA.

METHODS

Fecal samples were collected from 92 AA and 184 negative control (NC). Illumina HiSeq X sequencing platform was used for high-throughput sequencing of microbial populations. The sequencing results were annotated and compared with NCBI RefSeq database to find the microbial characteristics of AA. R-vegan package was used to analyze α diversity and β diversity. α diversity included box diagram, and β diversity included Principal Component Analysis (PCA), principal co-ordinates analysis (PCoA), and non-metric multidimensional scaling (NMDS). The AA risk prediction models were constructed based on six kinds of machine learning algorithms. In addition, unsupervised clustering methods were used to classify bacteria and viruses. Finally, the characteristics of bacteria and viruses in different subtypes were analyzed.

RESULTS

The abundance of Prevotella sp900557255, Alistipes putredinis, and Megamonas funiformis were higher in AA, while the abundance of Lilyvirus, Felixounavirus, and Drulisvirus were also higher in AA. The Catboost based model for predicting the risk of AA has the highest accuracy (bacteria test set: 87.27%; virus test set: 83.33%). In addition, 4 subtypes (B1V1, B1V2, B2V1, and B2V2) were distinguished based on the abundance of gut bacteria and enteroviruses (EVs). Escherichia coli D, Prevotella sp900557255, CAG-180 sp000432435, Phocaeicola plebeiuA, Teseptimavirus, Svunavirus, Felixounavirus, and Jiaodavirus are the characteristic bacteria and viruses of 4 subtypes. The results of Catboost model indicated that the accuracy of prediction improved after incorporating subtypes. The accuracy of discovery sets was 100%, 96.34%, 100%, and 98.46% in 4 subtypes, respectively.

CONCLUSION

Prevotella sp900557255 and Felixounavirus have high value in early warning of AA. As promising non-invasive biomarkers, gut microbes can become potential diagnostic targets for AA, and the accuracy of predicting AA can be improved by typing.

Solobacterium moorei promotes the progression of adenomatous polyps by causing inflammation and disrupting the intestinal barrier

BACKGROUND

Adenomatous polyps (APs) with inflammation are risk factors for colorectal cancer. However, the role of inflammation-related gut microbiota in promoting the progression of APs is unknown.

METHODS

Sequencing of the 16S rRNA gene was conducted to identify characteristic bacteria in AP tissues and normal mucosa. Then, the roles of inflammation-related bacteria were clarified by Spearman correlation analysis. Furthermore, colorectal HT-29 cells, normal colon NCM460 cells, and azoxymethane-treated mice were used to investigate the effects of the characteristic bacteria on progression of APs.

RESULTS

The expression levels of inflammation-related markers (diamine oxidase, D-lactate, C-reactive protein, tumor necrosis factor-α, interleukin-6 and interleukin-1β) were increased, whereas the expression levels of anti-inflammatory factors (interleukin-4 and interleukin-10) were significantly decreased in AP patients as compared to healthy controls. Solobacterium moorei (S. moorei) was enriched in AP tissues and fecal samples, and significantly positively correlated with serum inflammation-related markers. In vitro, S. moorei preferentially attached to HT-29 cells and stimulated cell proliferation and production of pro-inflammatory factors. In vivo, the incidence of intestinal dysplasia was significantly increased in the S. moorei group. Gavage of mice with S. moorei upregulated production of pro-inflammatory factors, suppressed proliferation of CD4+ and CD8+cells, and disrupted the integrity of the intestinal barrier, thereby accelerating progression of APs.

CONCLUSIONS

S. moorei accelerated the progression of AP in mice via activation of the NF-κB signaling pathway, chronic low-grade inflammation, and intestinal barrier disruption. Targeted reduction of S. moorei presents a potential strategy to prevent the progression of APs.

Solobacterium moorei promotes the progression of adenomatous polyps by causing inflammation and disrupting the intestinal barrier

BACKGROUND

Adenomatous polyps (APs) with inflammation are risk factors for colorectal cancer. However, the role of inflammation-related gut microbiota in promoting the progression of APs is unknown.

METHODS

Sequencing of the 16S rRNA gene was conducted to identify characteristic bacteria in AP tissues and normal mucosa. Then, the roles of inflammation-related bacteria were clarified by Spearman correlation analysis. Furthermore, colorectal HT-29 cells, normal colon NCM460 cells, and azoxymethane-treated mice were used to investigate the effects of the characteristic bacteria on progression of APs.

RESULTS

The expression levels of inflammation-related markers (diamine oxidase, D-lactate, C-reactive protein, tumor necrosis factor-α, interleukin-6 and interleukin-1β) were increased, whereas the expression levels of anti-inflammatory factors (interleukin-4 and interleukin-10) were significantly decreased in AP patients as compared to healthy controls. Solobacterium moorei (S. moorei) was enriched in AP tissues and fecal samples, and significantly positively correlated with serum inflammation-related markers. In vitro, S. moorei preferentially attached to HT-29 cells and stimulated cell proliferation and production of pro-inflammatory factors. In vivo, the incidence of intestinal dysplasia was significantly increased in the S. moorei group. Gavage of mice with S. moorei upregulated production of pro-inflammatory factors, suppressed proliferation of CD4+ and CD8+cells, and disrupted the integrity of the intestinal barrier, thereby accelerating progression of APs.

CONCLUSIONS

S. moorei accelerated the progression of AP in mice via activation of the NF-κB signaling pathway, chronic low-grade inflammation, and intestinal barrier disruption. Targeted reduction of S. moorei presents a potential strategy to prevent the progression of APs.

Salivary and fecal microbiota: potential new biomarkers for early screening of colorectal polyps

Objective

Gut microbiota plays an important role in colorectal cancer (CRC) pathogenesis through microbes and their metabolites, while oral pathogens are the major components of CRC-associated microbes. Multiple studies have identified gut and fecal microbiome-derived biomarkers for precursors lesions of CRC detection. However, few studies have used salivary samples to predict colorectal polyps. Therefore, in order to find new noninvasive colorectal polyp biomarkers, we searched into the differences in fecal and salivary microbiota between patients with colorectal polyps and healthy controls.

Methods

In this case-control study, we collected salivary and fecal samples from 33 patients with colorectal polyps (CP) and 22 healthy controls (HC) between May 2021 and November 2022. All samples were sequenced using full-length 16S rRNA sequencing and compared with the Nucleotide Sequence Database. The salivary and fecal microbiota signature of colorectal polyps was established by alpha and beta diversity, Linear discriminant analysis Effect Size (LEfSe) and random forest model analysis. In addition, the possibility of microbiota in identifying colorectal polyps was assessed by Receiver Operating Characteristic Curve (ROC).

Results

In comparison to the HC group, the CP group's microbial diversity increased in saliva and decreased in feces (p < 0.05), but there was no significantly difference in microbiota richness (p > 0.05). The principal coordinate analysis revealed significant differences in β-diversity of salivary and fecal microbiota between the CP and HC groups. Moreover, LEfSe analysis at the species level identified Porphyromonas gingivalis, Fusobacterium nucleatum, Leptotrichia wadei, Prevotella intermedia, and Megasphaera micronuciformis as the major contributors to the salivary microbiota, and Ruminococcus gnavus, Bacteroides ovatus, Parabacteroides distasonis, Citrobacter freundii, and Clostridium symbiosum to the fecal microbiota of patients with polyps. Salivary and fecal bacterial biomarkers showed Area Under ROC Curve of 0.8167 and 0.8051, respectively, which determined the potential of diagnostic markers in distinguishing patients with colorectal polyps from controls, and it increased to 0.8217 when salivary and fecal biomarkers were combined.

Conclusion

The composition and diversity of the salivary and fecal microbiota were significantly different in colorectal polyp patients compared to healthy controls, with an increased abundance of harmful bacteria and a decreased abundance of beneficial bacteria. A promising non-invasive tool for the detection of colorectal polyps can be provided by potential biomarkers based on the microbiota of the saliva and feces.

Mucosal Microbiota from Colorectal Cancer, Adenoma and Normal Epithelium Reveals the Imprint of Fusobacterium nucleatum in Cancerogenesis

An increasing amount of evidence suggests the emerging role of the gut microbiota in the development of colorectal cancer (CRC). This study aimed to elucidate the architecture of microbial communities within normal and neoplastic colonic mucosa.

METHODS

Microbiota were analyzed by NGS and by an ensemble of metagenomics analysis tools in a total of 69 tissues from 9 patients with synchronous colorectal neoplasia and adenomas (27 specimens: 9 from normal tissues, 9 adenomas, and 9 tumours), 16 patients with only colonic adenomas (32 specimens: 16 from normal tissues and 16 adenomas), and from healthy subjects (10 specimens of normal mucosa).

RESULTS

Weak differences were observed in alpha and beta metrics among the synchronous tissues from CRC and controls. Through pairwise differential abundance analyses of sample groups, an increasing trend of Rikenellaceae, Pseudomonas and Fusobacterium, and decreasing trends of Staphylococcus, Actinobacillus and Gemmiger were observed in CRC, while Staphylococcus and Bifidobacterium were decreased in patients with only adenomas. At RT-qPCR analysis, Fusobacterium nucleatum was significantly enriched in all the tissues of subjects with synchronous colorectal neoplasia.

CONCLUSION

Our findings provide a comprehensive view of the human mucosa-associated gut microbiota, emphasizing global microbial diversity mostly in synchronous lesions and proving the constant presence of Fusobacterium nucleatum, with its ability to drive carcinogenesis.