Inferring Bacterial Infiltration in Primary Colorectal Tumors From Host Whole Genome Sequencing Data

Integrating clinical and cross-cohort metagenomic features: a stable and non-invasive colorectal cancer and adenoma diagnostic model

Background: Dysbiosis is associated with colorectal cancer (CRC) and adenomas (CRA). However, the robustness of diagnostic models based on microbial signatures in multiple cohorts remains unsatisfactory. Materials and Methods: In this study, we used machine learning models to screen metagenomic signatures from the respective cross-cohort datasets of CRC and CRA (selected from CuratedMetagenomicData, each disease included 4 datasets). Then select a CRC and CRA data set from the CuratedMetagenomicData database and meet the requirements of having both metagenomic data and clinical data. This data set will be used to verify the inference that integrating clinical features can improve the performance of microbial disease prediction models. Results: After repeated verification, we selected 20 metagenomic features that performed well and were stably expressed within cross-cohorts to represent the diagnostic role of bacterial communities in CRC/CRA. The performance of the selected cross-cohort metagenomic features was stable for multi-regional and multi-ethnic populations (CRC, AUC: 0.817-0.867; CRA, AUC: 0.766-0.833). After clinical feature combination, AUC of our integrated CRC diagnostic model reached 0.939 (95% CI: 0.932-0.947, NRI=30%), and that of the CRA integrated model reached 0.925 (95%CI: 0.917-0.935, NRI=18%). Conclusion: In conclusion, the integrated model performed significantly better than single microbiome or clinical feature models in all cohorts. Integrating cross-cohort common discriminative microbial features with clinical features could help construct stable diagnostic models for early non-invasive screening for CRC and CRA.

Interaction between Bacteria and the Immune System for Cancer Immunotherapy: The α-GalCer Alliance

Non-conventional T cells, such as γδ T and invariant natural killer T (iNKT) cells, are emerging players in fighting cancer. Alpha-galactosylceramide (α-GalCer) is used as an exogenous ligand to activate iNKT cells. Human cells don’t have a direct pathway producing α-GalCer, which, however, can be produced by bacteria. We searched the literature for bacteria strains that are able to produce α-GalCer and used available sequencing data to analyze their presence in human tumor tissues and their association with survival. The modulatory effect of antibiotics on the concentration of α-GalCer was analyzed in mice. The human gut bacteria Bacteroides fragilis, Bacteroides vulgatus, and Prevotella copri produce α-GalCer structures that are able to activate iNKT cells. In mice, α-GalCer was depleted upon treatment with vancomycin. The three species were detected in colon adenocarcinoma (COAD) and rectum adenocarcinoma tissues, and Prevotella copri was also detected in bone tumors and glioblastoma tissues. Bacteroides vulgatus in COAD tissues correlated with better survival. In conclusion, α-GalCer-producing bacteria are part of the human gut microbiome and can infiltrate tumor tissues. These results suggest a new mechanism of interaction between bacteria and immune cells: α-GalCer produced by bacteria may activate non-conventional T cells in tumor tissues, where they can exert a direct or indirect anti-tumor activity.

The association between Fusobacterium nucleatum and cancer colorectal: A systematic review and meta-analysis

INTRODUCTION

The etiological factors of colorectal cancer (CRC) are not precisely known, although genetic and environmental factors have been implicated. A possible association with Fusobacterium nucleatum may provide opportunities for an early diagnosis.

OBJECTIVE

To review studies that address the association between F. nucleatum and CRC.

METHODS

The MEDLINE PubMed database was searched using the terms «colorectal cancer» and "Fusobacterium nucleatum", retrieving publications published up to January 1 2020. Stata software was used for a meta-analysis.

RESULTS

The systematic review included 57 articles. Meta-analysis results indicated a more frequent presence of F. nucleatum in CRC tumour tissue samples in comparison to control samples of healthy tissue, with an odds ratio of 4.558 (95% CI: 3.312-6.272), and in comparison, to control samples of colorectal adenomas, with an odds ratio of 3.244 (95 % CI: 2.359-4.462).

CONCLUSION

There is a more frequent resence of F. nucleatum in the CRC. However, further studies are needed to verify this relationship.

Molecular Mechanisms of Tumor Immunomodulation in the Microenvironment of Colorectal Cancer

Colorectal cancer remains one of the most important health challenges in our society. The development of cancer immunotherapies has fostered the need to better understand the anti-tumor immune mechanisms at play in the tumor microenvironment and the strategies by which the tumor escapes them. In this review, we provide an overview of the molecular interactions that regulate tumor inflammation. We particularly discuss immunomodulatory cell-cell interactions, cell-soluble factor interactions, cell-extracellular matrix interactions and cell-microbiome interactions. While doing so, we highlight relevant examples of tumor immunomodulation in colorectal cancer.

First case of an invasive Bacteroides dorei infection detected in a patient with a mycotic aortic aneurysm-raising a rebellion of major indigenous bacteria in humans: a case report and review

Background

Bacteroides dorei is an anaerobic gram-negative bacterium first described in 2006. Because of the high similarity in mass spectra between B. dorei and Bacteroides vulgatus, discriminating between these species is arduous in clinical practice. In recent decades, 16S rRNA gene sequencing has been a complementary method for distinguishing taxonomically close bacteria, including B. dorei and B. vulgatus, at the genus and species levels. Consequently, B. dorei has been shown to contribute to some diseases, including type 1 autoimmune diabetes mellitus and atherosclerotic diseases. However, there are no reports on invasive infectious diseases caused by B. dorei. This report describes the first case of direct invasion and colonisation of human tissue by B. dorei, thus providing a warning regarding the previously proposed application of B. dorei as a live biotherapeutic for atherosclerotic diseases.

Case presentation

A 78-year-old Japanese man complained of intermittent chest/back pain and was diagnosed with a mycotic thoracic aortic aneurysm by enhanced computed tomography on admission. Despite strict blood pressure control and empirical antibiotic therapy, the patient’s condition worsened. To prevent aneurysmal rupture and eliminate infectious foci, the patient underwent surgical treatment. The resected specimen was subjected to tissue culture and 16S rRNA gene sequencing analysis to identify pathogenic bacteria. A few days after the surgery, culture and sequencing results revealed that the pathogen was B. dorei/B. vulgatus and B. dorei, respectively. The patient was successfully treated with appropriate antibacterial therapy and after improvement, was transferred to another hospital for rehabilitation on postoperative day 34. There was no recurrence of infection or aneurysm after the patient transfer.

Conclusions

This report describes the first case of invasive infectious disease caused by B. dorei, casting a shadow over its utilisation as a probiotic for atherosclerotic diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06345-8.

The association between Fusobacterium nucleatum and cancer colorectal: a systematic review and meta-analysis

INTRODUCTION

The etiological factors of colorectal cancer (CRC) are not precisely known, although genetic and environmental factors have been implicated. A possible association with Fusobacterium nucleatum may provide opportunities for an early diagnosis.

OBJECTIVE

To review studies that address the association between F. nucleatum and CRC.

METHODS

The MEDLINE PubMed database was searched using the terms «colorectal cancer» and «Fusobacterium nucleatum», retrieving publications published up to January 1 2020. Stata software was used for a meta-analysis.

RESULTS

The systematic review included 57 articles. Meta-analysis results indicated a more frequent presence of F. nucleatum in CRC tumor tissue samples in comparison to control samples of healthy tissue, with an odds ratio of 4.558 (95% CI: 3.312-6.272), and in comparison, to control samples of colorectal adenomas, with an odds ratio of 3.244 (95% CI: 2.359-4.462).

CONCLUSION

There is a more frequent presence of F. nucleatum in the CRC. However, further studies are needed to verify this relationship.

Establishment of an immune-related gene pair model to predict colon adenocarcinoma prognosis

Background

Colon cancer is the most common type of gastrointestinal cancer and has high morbidity and mortality. Colon adenocarcinoma (COAD) is the main pathological type of colon cancer, and much evidence has supported the correlation between the prognosis of COAD and the immune system. The current study aimed to develop a robust prognostic immune-related gene pair (IRGP) model to estimate the overall survival of patients with COAD.

Methods

The gene expression profiles and clinical information of patients with colon adenocarcinoma were obtained from the TCGA and GEO databases and were divided into training and validation cohorts. Immune genes were selected that showed a significant association with prognosis.

Results

Among 1647 immune genes, a model with 17 IRGPs was built that was significantly associated with OS in the training cohort. In the training and validation datasets, the IRGP model divided patients into the high-risk group and low-risk group, and the prognosis of the high-risk group was significantly worse (P<0.001). Univariate and multivariate Cox proportional hazard analyses confirmed the feasibility of this model. Functional analysis confirmed that multiple tumor progression and stem cell growth-related pathways were upregulated in the high-risk groups. Regulatory T cells and macrophages M0 were significantly highly expressed in the high-risk group.

Conclusion

We successfully constructed an IRGP model that can predict the prognosis of COAD, providing new insights into the treatment strategy of COAD.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12885-020-07532-7.

Clostridioides difficile antibody response of colorectal cancer patients versus clinically healthy individuals

Dysbiosis, defined as an imbalance in the gut microbiota caused by too few beneficial bacteria and an overgrowth of bad bacteria, yeast, and/or parasites, is now being associated with several diseases, including the development of colorectal carcinoma (CRC). In this study, the potential association of Clostridioides difficile (formerly Clostridium difficile) with CRC was investigated. Plasma samples obtained from preoperative histologically confirmed CRC patients (n=39) and their age- and sex-matched clinically healthy controls (n=39) were analyzed for antibodies to toxin B of C. difficile (anti-tcdB) by enzyme-linked immunosorbent assay (ELISA). A significantly greater number (p=0.012) of CRC cases (n=26/39, 66.7%) had anti-tcdB IgG levels above the cutoff value compared with controls (n=12/39, 30.8%). Eight cases (8/39, 20.5%) and none of the controls registered anti-tcdB IgA levels above the cutoff value (p=0.0039). Anti-tcdB IgG and IgA levels were not shown to be significantly associated with tumor grade or tumor stage. Anti-tcdB IgG showed 66.7% sensitivity and 69.2% specificity. For anti-tcdB IgA, sensitivity and specificity were 20.5% and 100%, respectively. The positive predictive values for anti-tcdB IgA and IgG were 100% and 68.4%, respectively. The anti-tcdB IgA and IgG negative predictive values were 55.7% and 67.5%, respectively. The results suggest the potential association of C. difficile with CRC and anti-tcdB levels, particularly the IgA level. Hence, anti-tcdB antibodies can be candidate serologic markers for CRC.