Patients with colorectal cancer have identical strains of Fusobacterium nucleatum in their colorectal cancer and oral cavity

A pilot study of gut mucosal and faecal microbiota in rectal cancer: associations with histological response and adverse events following preoperative chemoradiotherapy

AIM

Preoperative chemoradiotherapy (CRT) is administered for locally advanced rectal cancer (LARC); however, its efficacy and toxicity vary among patients. This study aimed to elucidate the relationship between the gut microbiota and the effectiveness and adverse events of CRT.

METHODS

This prospective study included 21 patients with LARC with no history of antibiotic or probiotic administration for 6 months. Tumour mucosa, non-tumour mucosa and faecal samples were collected before and after CRT, and bacterial DNA was extracted. Metataxonomic analysis targeting the V3 and V4 regions of the 16S rRNA gene was conducted to determine the diversity and composition of the microbiota. Linear discriminant analysis effect size (LEfSe) was used to explore potential bacterial taxa predicting pathological complete response (pCR) and treatment-associated diarrhoea, which are major adverse events of CRT.

RESULTS

Among the 21 patients, five achieved pCR and seven experienced severe treatment-associated diarrhoea. There were no significant differences in α-diversity and β-diversity of the microbiota between the groups at any sampling sites before or after CRT. Exploratory analysis using LEfSe identified Peptostreptococcus, Coprococcus and Phoceaicola in the tumour mucosa before CRT as significant indicators for achieving pCR. Additionally, Collinsella, Haemophilus and Desulfovibrionaceae are associated with treatment-associated diarrhoea. Microbiome composition changed before and after CRT, with a notable decrease in the genus Fusobacterium_C and other taxa. β-diversity in the tumour area also changed significantly (P = 0.03).

CONCLUSIONS

This study suggests an association between the gut microbiota, the therapeutic effectiveness of CRT and the occurrence of treatment-associated diarrhoea in rectal cancer. These results indicate the potential for predicting treatment efficacy and adverse events based on the microbiota composition.

Multidimensional differences of right- and left-sided colorectal cancer and their impact on targeted therapies

Despite advances in metastatic colorectal cancer (mCRC) treatment, long-term survival remains poor, particularly in right-sided colorectal cancer (RCRC), which has a worse prognosis compared to left-sided CRC (LCRC). This disparity is driven by the complex biological diversity of these malignancies. RCRC and LCRC differ not only in clinical presentation and outcomes but also in their underlying molecular and genetic profiles. This article offers a detailed literature review focusing on the distinctions between RCRC and LCRC. We explore key differences across embryology, anatomy, pathology, omics, and the tumor microenvironment (TME), providing insights into how these factors contribute to prognosis and therapeutic responses. Furthermore, we examine the therapeutic implications of these differences, considering whether the conventional classification of CRC into right- and left-sided forms should be refined. Recent molecular findings suggest that this binary classification may overlook critical biological complexities. Therefore, we propose that future approaches should integrate molecular insights to better guide personalized treatments, especially anti-EGFR therapies, and improve patient outcomes.

Fusobacterium nucleatum in Colorectal Cancer: Ally Mechanism and Targeted Therapy Strategies

Fusobacterium nucleatum (Fn), an oral anaerobic commensal, has recently been identified as a crucial oncogenic contributor to colorectal cancer pathogenesis through its ectopic colonization in the gastrointestinal tract. Accumulating evidence reveals its multifaceted involvement in colorectal cancer initiation, progression, metastasis, and therapeutic resistance to conventional treatments, including chemotherapy, radiotherapy, and immunotherapy. This perspective highlights recent advances in anti-Fn strategies, including small-molecule inhibitors, nanomedicines, and biopharmaceuticals, while critically analyzing the translational barriers in developing targeted antimicrobial interventions. We further propose potential strategies to overcome current challenges in Fn modulation, aiming to pave the way for more effective therapeutic interventions and better clinical outcomes.

Clinical translation of microbiome research

The landscape of clinical microbiome research has dramatically evolved over the past decade. By leveraging in vivo and in vitro experimentation, multiomic approaches and computational biology, we have uncovered mechanisms of action and microbial metrics of association and identified effective ways to modify the microbiome in many diseases and treatment modalities. This Review explores recent advances in the clinical application of microbiome research over the past 5 years, while acknowledging existing barriers and highlighting opportunities. We focus on the translation of microbiome research into clinical practice, spearheaded by Food and Drug Administration (FDA)-approved microbiome therapies for recurrent Clostridioides difficile infections and the emerging fields of microbiome-based diagnostics and therapeutics. We highlight key examples of studies demonstrating how microbiome mechanisms, metrics and modifiers can advance clinical practice. We also discuss forward-looking perspectives on key challenges and opportunities toward integrating microbiome data into routine clinical practice, precision medicine and personalized healthcare and nutrition.

Combining gut microbiota modulation and immunotherapy: A promising approach for treating microsatellite stable colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and lethal cancers worldwide, ranking third in incidence and second in mortality. While immunotherapy has shown promise in patients with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H), its effectiveness in proficient mismatch repair (pMMR) or microsatellite stable (MSS) CRC remains limited. Recent advances highlight the gut microbiota as a potential modulator of anti-tumor immunity. The gut microbiome can significantly influence the efficacy of immune checkpoint inhibitors (ICIs), especially in pMMR/MSS CRC, by modulating immune responses and systemic inflammation. This review explores the role of the gut microbiota in pMMR/MSS CRC, the mechanisms by which it may enhance immunotherapy, and current strategies for microbiota modulation. We discuss the potential benefits of combining microbiota-targeting interventions with immunotherapy to improve treatment outcomes for pMMR/MSS CRC patients.

Oxidative Stress by H2O2 as a Potential Inductor in the Switch from Commensal to Pathogen in Oncogenic Bacterium Fusobacterium nucleatum

BACKGROUND

Fusobacterium nucleatum is a pathobiont that plays a dual role as both a commensal and a pathogen. The oral cavity typically harbors this anaerobic, Gram-negative bacterium. At the same time, it is closely linked to colorectal cancer due to its potential involvement in tumor progression and resistance to chemotherapy. The mechanism by which it transforms from a commensal to a pathogen remains unknown. For this reason, we investigated the role of oxidative status as an initiatory factor in changing the bacterium's pathogenicity profile.

METHODS

A clinical strain of F. nucleatum subsp. animalis biofilm was exposed to different oxidative stress levels through varying subinhibitory amounts of H2O2. Subsequently, we investigated the bacterium's behavior in vitro by infecting the HT-29 cell line. We evaluated bacterial colonization, volatile sulfur compounds production, and the infected cell's oxidative status by analyzing HMOX1, pri-miRNA 155, and 146a gene expression.

RESULTS

The bacterial colonization rate, dimethyl sulfide production, and pri-miRNA 155 levels all increased when stressed bacteria were used, suggesting a predominant pathogenic function of these strains.

CONCLUSIONS

The response of F. nucleatum to different oxidative conditions could potentially explain the increase in its pathogenic traits and the existence of environmental factors that may trigger the bacterium's pathogenicity and virulence.

Periodontitis and gastrointestinal cancer: a nationwide cohort study of NHANES 2009-2014

The association between periodontitis and gastrointestinal tract (GIT) cancer has undergone extensive investigation. However, there is ongoing controversy regarding the impact of periodontitis on the incidence and mortality rates among GIT cancer patients. This study aims to clarify the relationship between periodontitis and the risk as well as mortality rates of GIT cancer.

METHODS

The data utilized in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) database for the years 2009-2014, which included a total of 10,706 participants from the United States. The incidence and mortality rates of GIT cancer were analyzed in relation to periodontitis. To ensure the reliability of the results, additional adjustments for covariates and stratification analyses were conducted.

RESULTS

In the multivariate logistic regression analysis, various variables such as age, sex, race, BMI, income, education, smoking, alcohol consumption, hypertension, hyperlipidemia, and diabetes mellitus were adjusted for. The analysis revealed no positive association between periodontitis and an increased risk of total cancer or GIT cancer including colorectal cancer. However, periodontitis was found to be significantly associated with higher mortality rates among participants for all-cause (HR: 1.58; 95% CI: 1.26-2.00; P < 0.001), GIT cancer (HR: 1.65; 95% CI: 1.24-2.20; P < 0.001), and colorectal cancer (HR: 1.65; 95% CI: 1.24-2.19; P < 0.001) individually.

CONCLUSIONS

The study demonstrates that periodontitis is not associated with an increased risk of incidence for total cancer, or GIT cancer including colorectal cancer. However, it is significantly associated with a higher risk of mortality for all-cause, GIT cancer, and colorectal cancer among participants in the NHANES study.

Involvement of Oral Microbiome in the Development of Oral Malignancy

OBJECTIVE

This study aimed to identify periodontal pathogens involved in the onset and progression of OSCC.

METHODS

Saliva samples were collected from 112 patients without oral mucosal diseases (OMDs) as controls; 36 patients with oral potentially malignant disorders (OPMDs); and 104 patients with OSCC. Periodontal examinations were performed on all patients. Endpoint PCR was performed for seven species of oral pathogens. The 16S rRNA analysis was performed using 20 DNA samples from each group.

RESULTS

Periodontitis tended to worsen in the OMDs group compared to the control group. The number of oral bacteria was significantly higher in the OSCC group than in the other groups. The detection rates of P. gingivalis and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) were significantly higher in the OSCC group than those in the control group. From 16S rRNA analysis, the relative abundance of Prevotella buccae and intermedia was significantly higher in OSCC than in the control. Moreover, LPS derived from P. gingivalis contributes to the early development of oral epithelial precancerous lesions and carcinomas in mice.

CONCLUSIONS

Specific periodontal pathogens are present in the oral cavities of patients with OPMDs and OSCC, and changes in the bacterial flora due to their presence may contribute to the onset and progression of OMDs.

Global prevalence of Fusobacterium nucleatum and Bacteroides fragilis in patients with colorectal cancer: an overview of case reports/case series and meta-analysis of prevalence studies

BACKGROUND

Colorectal cancer (CRC) is the second deadliest carcinoma across the globe and has been known as a multi-factor induced-disease. Emerging research have demonstrated that bacterial colonization may contribute to the initiation and promotion of the CRC. The presence of Fusobacterium nucleatum (F. nucleatum) and Bacteroides fragilis (B. fragilis) in the gut is associated with the development of CRC. In this study, the prevalence of F. nucleatum and B. fragilis among CRC patients has been assessed worldwide through a systematic review and meta-analysis.

METHODS

The extensive search was performed using "Fusobacterium nucleatum", "Bacteroides fragilis", "Colorectal cancer" and all relevant keywords. Then, a systematic paper screening was done following a comprehensive search in Embase, Web of Science, and PubMed databases while the time range was limited between the years 2000 and 2024. Afterwards, statistical analysis was performed utilizing the comprehensive meta-analysis (CMA) software (version 2.0, Biostat, USA).

RESULTS

According to the meta-analysis of prevalence studies, the prevalence of F. nucleatum among 19 countries and B. fragilis among 10 countries were indicated to be 38.9% (95% CI 33.7-44.3%) and 42.5% (95% CI 34.4-51.1%), respectively, among the CRC patients. It was then revealed that Asia had the highest prevalence of F. nucleatum while most of the B. fragilis isolates in CRC cases were reported in European countries. Moreover, the data suggested that the most common comorbidity observed among the CRC cases was diabetes.

CONCLUSION

Our results emphasized the high prevalence of F. nucleatum and B. fragilis in CRC patients. Based on this meta-analysis review, regulating the gut microbiota in CRC patients seemed to be a promising approach to improving the efficacy of CRC therapy.

Histopathological study of the localization/distribution of Fusobacterium nucleatum in esophageal cancer

Fusobacterium nucleatum is implicated in esophageal cancer; however, its distribution in esophageal cancer tissues remains unknown. This study aimed to clarify the presence and distribution of F. nucleatum in esophageal cancer tissues using fluorescence in situ hybridization (FISH). Tissues collected from 70 patients with esophageal squamous cell carcinoma were examined using FISH. Corresponding normal epithelium and metastatic lymph nodes were assessed. F. nucleatum was identified more frequently in esophageal cancer tissues than in the normal epithelium. F. nucleatum also showed significant correlation with factors associated with tumor progression, such as pT factor and tumor size. As tumor progression advanced, the area occupied by F. nucleatum gradually became larger. F. nucleatum positivity was observed around the deep edge of the tumor nest (border-dense type) or identified diffusely in the tumor nest (diffuse distributed type). Furthermore, F. nucleatum was observed in metastatic lymph nodes, lesions of venous invasion, and walls of veins in normal epithelium. In conclusion, we visualized F. nucleatum using FISH and identified different distribution patterns of F. nucleatum, highlighting the spot density of its presence in tumor tissues. Recognizing this quantitative change is pivotal for establishing F. nucleatum as a reliable biomarker.

Bacterial small molecule metabolites implicated in gastrointestinal cancer development

Numerous associations have been identified between cancer and the composition and function of the human microbiome. As cancer remains the second leading global cause of mortality, investigating the carcinogenic contributions of microbiome members could advance our understanding of cancer risk and support potential therapeutic interventions. Although fluctuations in bacterial species have been associated with cancer progression, studying their small molecule metabolites offers one avenue to establish support for causal relationships and the molecular mechanisms governing host-microorganism interactions. In this Review, we explore the expanding repertoire of small molecule metabolites and their mechanisms implicated in the risk of developing gastrointestinal cancers.

Link Between Oral and Gut Microbiomes: The Oral-Gut Axis

In the last decades, groundbreaking research on the human microbiome has changed our reductionist conception of the etiology and pathogenesis of several chronic diseases. As a result, we have come to appreciate the significance of a balanced microbiome in maintaining human health. In this context, the upper and lower gastrointestinal tracts (GITs) comprise the most abundant and diverse microbiotas of the human body. In addition to its diversity, functional redundancy, and temporal stability, a healthy GIT microbiome is characterized by its body site specificity. In fact, current evidence has indicated that the translocation of oral species to the gut environment through the oral-gut axis is increased in an array of illnesses, including chronic inflammatory and metabolic diseases, neurological disorders, and cancer. Oral pathogens have also been shown to promote gut dysbiosis and systemic inflammation in animal models. Yet, some level of overlapping between oral and gut microbiomes may occur without disruption of these microbial communities and loss of site specificity. The uniqueness of each host-microbiome entity may hinder our ability to define a "universal" normal GIT microbiome. Despite that, this chapter summarizes the predominant health-related taxa along the human GIT, as well as their role in the physiology and immunity of the digestive system. Some mechanisms that may lead to disturbances and relevant shifts in the oral and gut microbiomes of major inflammatory chronic diseases are also pointed out. Lastly, oral-fecal microbial signatures are presented as potential biomarkers for several oral and systemic disorders. The recognition of such symbiotic/dysbiotic microbial profiles may provide insights into the development of more accurate early diagnosis and therapeutic ecological approaches to restore the balance of the GIT microbiome.

Fusobacterium nucleatum is enriched in invasive biofilms in colorectal cancer

Fusobacterium nucleatum is an oral bacterium known to colonize colorectal tumors, where it is thought to play an important role in cancer progression. Recent advances in sequencing and phenotyping of F. nucleatum have revealed important differences at the subspecies level, but whether these differences impact the overall tumor ecology, and tumorigenesis itself, remain poorly understood. In this study, we sought to characterize Fusobacteria in the tumor microbiome of a cohort of individuals with CRC through a combination of molecular, spatial, and microbiologic analyses. We assessed for relative abundance of F. nucleatum in tumors compared to paired normal tissue, and correlated abundance with clinical and pathological features. We demonstrate striking enrichment of F. nucleatum and the recently discovered subspecies animalis clade 2 (Fna C2) specifically in colon tumors that have biofilms, highlighting the importance of complex community partnerships in the pathogenesis of this important organism.

A Longitudinal Dynamic Change in LMR Can Be a Biomarker for Recurrence in Fusobacterium Nucleatum-Positive Colorectal Cancer Patients

Purpose

This study assessed lymphocyte-to-monocyte ratio (LMR) changes to predict postoperative recurrence in Fusobacterium nucleatum-positive (Fn-positive) CRC patients.

Patients and Methods

Clinical information and paraffin tissue specimens were collected from a retrospective cohort of 332 patients. The abundance of Fn in tumor tissue was measured using a quantitative polymerase chain reaction. We evaluated the prognostic value and diagnostic performance of the dynamic changes of LMR from pre-operative to post-treatment (pr-LMR-po) and the dynamic alterations of LMR from pre-operative to post-treatment to pre-end of follow-up (pr-LMR-f) in predicting recurrence in Fn-positive CRC.

Results

In the total cohort and adjuvant therapy group cohort, pr-LMR-po independently predicted recurrence-free survival in Fn-positive CRC patients. In the adjuvant therapy group, pr-LMR-po (High-High vs Low-Low: HR: 3.896, 95% CI: 1.503-10.095, p=0.005) was particularly significant. Meanwhile, pr-LMR-f can serve as a predictive biomarker for Fn-positive CRC recurrence, especially in the adjuvant therapy group cohort where the c-statistic for pr-LMR-f was 0.825 (95% CI: 0.804-0.8251), with a sensitivity of 83.6% and a specificity of 79.3%. Compared to the overall adjuvant therapy group cohort, the prognostic performance of pr-LMR-f was superior in the Fn-positive CRC adjuvant therapy group cohort (AUC: 0.825 VS 0.711). Finally, we constructed a prediction model combining pr-LMR-f and CEA. After internal validation using the bootstrap resampling, the model had an AUC of 0.9295, a sensitivity of 94%, and a specificity of 72.7% in the Fn-positive CRC adjuvant therapy group cohort.

Conclusion

This study found that pr-LMR-po predicts Fn-positive CRC prognosis, and pr-LMR-f may predict Fn-positive CRC recurrence.

Microbiome Differences in Colorectal Cancer Patients and Healthy Individuals: Implications for Vaccine Antigen Discovery

Background

Colorectal cancer (CRC) is the third most prevalent cancer worldwide, with numerous risk factors contributing to its development. Recent research has illuminated the significant role of the gut microbiota in CRC pathogenesis, identifying various microbial antigens as potential targets for vaccine development.

Aim

This review aimed at exploring the potential sources of microbial antigens that could be harnessed to create effective CRC vaccines and understand the role of microbiome-CRC interactions in carcinogenesis.

Methods

A comprehensive search of original research and review articles on the pathological links between key microbial candidates, particularly those more prevalent in CRC tissues, was conducted. This involved extensive use of the PubMed and Medline databases, as well as the Google Scholar search engine, utilizing pertinent keywords. A total of one hundred and forty-three relevant articles in English, mostly published between 2018 and 2024, were selected.

Results

Numerous microbes, particularly bacteria and viruses, are significantly overrepresented in CRC tissues and have been shown to promote tumorigenesis by inducing inflammation and modulating the immune system. This makes them promising candidates for antigens in the development of CRC vaccines.

Conclusion

The selection of microbial antigens focuses on their capacity to trigger a strong immune response and their link to tumor presence and progression. Identifying and validating these antigens through preclinical testing is essential in developing a CRC vaccine.

The oral-gut microbiome axis in health and disease

The human body hosts trillions of microorganisms throughout many diverse habitats with different physico-chemical characteristics. Among them, the oral cavity and the gut harbour some of the most dense and diverse microbial communities. Although these two sites are physiologically distinct, they are directly connected and can influence each other in several ways. For example, oral microorganisms can reach and colonize the gastrointestinal tract, particularly in the context of gut dysbiosis. However, the mechanisms of colonization and the role that the oral microbiome plays in causing or exacerbating diseases in other organs have not yet been fully elucidated. Here, we describe recent advances in our understanding of how the oral and intestinal microbiota interplay in relation to their impact on human health and disease.

Relationship between oral microbiota and colorectal cancer: A systematic review

This systematic review aims to investigate the microbial basis underlying the association between oral microbiota and colorectal cancer. A comprehensive search was conducted across four databases, encompassing potentially relevant studies published up to April 2024 related to the PECO question: "Is there a differentiation in oral microbial composition between adult patients diagnosed with colorectal cancer compared to healthy patients?". The Newcastle-Ottawa Scale was used to evaluate the quality of the studies included. The level of evidence was assessed through the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) tool. Sixteen studies fulfilled the eligibility criteria. Based on low to moderate evidence profile, high levels of certain subspecies within Firmicutes (such as Streptococcus anginosus, Peptostreptococcus stomatis, S. koreensis, and S. gallolyticus), Prevotella intermedia, Fusobacterium nucleatum, and Neisseria oralis were found to be associated with colorectal cancer. Conversely, certain bacteria (e.g., Lachnospiraceae, F. periodonticum, and P. melaninogenica) could exert a symbiotic protective effect against colorectal cancer. Based on existing evidence, it appears that variations in oral microbiota composition exist among individuals with and without colorectal cancer. However, further research is necessary to determine the mechanisms of oral dysbiosis in colorectal carcinogenesis.

The role of Fusobacterium nucleatum in the pathogenesis of colon cancer

Previously, many studies have reported changes in the gut microbiota of patients with colorectal cancer (CRC). While CRC is a well-described disease, the relationship between its development and features of the intestinal microbiome is still being understood. Evidence linking Fusobacterium nucleatum enrichment in colorectal tumor tissue has prompted the elucidation of various molecular mechanisms and tumor-promoting attributes. In this review we highlight various aspects of our understanding of the relationship between the development of CRC and the alteration of intestinal microbiome, focusing specifically on the role of F. nucleatum. As the amount of F. nucleatum DNA in CRC tissue is associated with shorter survival, it may potentially serve as a prognostic biomarker, and most importantly may open the door for a role in CRC treatment.

New Insights into Mucosa-Associated Microbiota in Paired Tumor and Non-Tumor Adjacent Mucosal Tissues in Colorectal Cancer Patients

BACKGROUND/OBJECTIVE

Colorectal cancer (CRC) is one of the most common cancers worldwide. Increasing scientific evidence supports the idea that gut microbiota dysbiosis accompanies colorectal tumorigenesis, and these changes could be causative. Implementing gut microbiota analysis in clinical practice is limited by sample type, sequencing platform and taxonomic classification. This article aims to address these limitations, providing new insights into the microbiota associated with CRC pathogenesis and implementing its analyses in personalized medicine.

METHODS

To that aim, we evaluate differences in the bacterial composition of 130 paired tumor and non-tumor adjacent tissues from a cohort of CRC patients from the Biobank of the University of Navarra, Spain. The V3-V4 region of the 16S rRNA gene was amplified, sequenced using the MinION platform, and taxonomically classified using the NCBI database.

RESULTS

To our knowledge, this is the first study to report an increased relative abundance of Streptococcus periodonticum and a decreased relative abundance of Corynebacterium associated with CRC. Genera such as Fusobacterium, Leptotrichia and Streptococcus showed higher relative abundances in tumor than in non-tumor tissues, as previously described in the literature. Specifically, we identified higher levels of Fusobacterium animalis, Fusobacterium nucleatum, Fusobacterium polymorphum and S. periodonticum in tumor tissues. In contrast, genera such as Bacteroides and Corynebacterium showed lower relative abundances in tumor tissues. There were also differences at the taxonomic level between tumor locations.

CONCLUSIONS

These results, consistent with previous studies, further support the hypothesis that Leptotrichia and Fusobacterium contribute to CRC progression, with F. nucleatum and F. animalis proposed as key CRC pathogenic taxa. Overall, these results contribute to a better understanding of the CRC-associated microbiota, addressing critical barriers to its implementation in personalized medicine.

Exploring micronutrients and microbiome synergy: pioneering new paths in cancer therapy

The human microbiome is the complex ecosystem consisting of trillions of microorganisms that play a key role in developing the immune system and nutrient metabolism. Alterations in the gut microbiome have been linked to cancer initiation, progression, metastasis, and response to treatment. Accumulating evidence suggests that levels of vitamins and minerals influence the gut environment and may have implications for cancer risk and progression. Bifidobacterium has been reported to reduce the colorectal cancer risk by binding to free iron. Additionally, zinc ions have been shown to activate the immune cells and enhance the effectiveness of immunotherapy. Higher selenium levels have been associated with a reduced risk of several cancers, including colorectal cancer. In contrast, enhanced copper uptake has been implicated in promoting cancer progression, including colon cancer. The interaction between cancer and gut bacteria, as well as dysbiosis impact has been studied in animal models. The interplay between prebiotics, probiotics, synbiotics, postbiotics and gut bacteria in cancer offers the diverse physiological benefits. We also explored the particular probiotic formulations like VSL#3, Prohep, Lactobacillus rhamnosus GG (LGG), etc., for their ability to modulate immune responses and reduce tumor burden in preclinical models. Targeting the gut microbiome through antibiotics, bacteriophage, microbiome transplantation-based therapies will offer a new perspective in cancer research. Hence, to understand this interplay, we outline the importance of micronutrients with an emphasis on the immunomodulatory function of the microbiome and highlight the microbiome's potential as a target for precision medicine in cancer treatment.

Unveiling the Hidden Links: Periodontal Disease, Fusobacterium Nucleatum, and Cancers

PURPOSE OF REVIEW

Fusobacterium nucleatum (F. nucleatum), an anaerobic, gram-negative microbe, commonly found in human dental biofilm and the gut flora. It has long been known to have a higher concentration in periodontal disease and has recently been implicated in both oral and distant cancers such as colorectal, gastrointestinal, esophageal, breast, pancreatic hepatocellular, and genitourinary cancers. However, the mechanism of its involvement in the development of cancer has not been fully discussed. This review aims to cover biological molecular and clinical aspects of F. nucleatum and cancers.

RECENT FINDINGS

Studies indicate F. nucleatum promotes tumor development through chronic inflammation, immune evasion, cell proliferation activation, and direct cell interactions, as in oral squamous cell carcinoma (OSCC). In colorectal cancer (CRC), F. nucleatum contributes to tumorigenesis through β-catenin signaling and NF-κB activation. It also induces autophagy, leading to chemoresistance in CRC and esophageal cancers, and enhances tumor growth and metastasis in breast cancer by reducing T-cell infiltration. F. nucleatum is linked to carcinogenesis and increased bacterial diversity in OSCC, with improved oral hygiene potentially preventing OSCC. F. nucleatum triggers cancer by causing mutations and epigenetic changes through cytokines and reactive oxygen species. It also promotes chemoresistance in CRC. F. nucleatum may potentially serve as a diagnostic tool in various cancers, with non-invasive detection methods available. Further investigation is needed to discover its potential in the diagnosis and treatment of OSCC and other cancers.

Gut and oral microbiota in gynecological cancers: interaction, mechanism, and therapeutic value

Gynecologic cancers develop from the female reproductive organs. Microbial dysbiosis in the gut and oral cavity can communicate with each other through various ways, leading to mucosal destruction, inflammatory response, genomic instability, and ultimately inducing cancer and worsening. Here, we introduce the mechanisms of interactions between gut and oral microbiota and their changes in the development of gynecologic tumors. In addition, new therapeutic approaches based on microbiota modulation are discussed.

Fusobacterium nucleatum extracellular vesicles are enriched in colorectal cancer and facilitate bacterial adhesion

Fusobacterium nucleatum in colorectal cancer (CRC) tissue is implicated at multiple stages of the disease, while the mechanisms underlying bacterial translocation and colonization remain incompletely understood. Herein, we investigated whether extracellular vesicles derived from F. nucleatum (FnEVs) have impacts on bacterial colonization. In mice with colitis-related CRC, a notable enrichment of FnEVs was observed, leading to a significant increase in intratumor colonization by F. nucleatum and accelerated progression of CRC. The enrichment of FnEVs in clinical CRC tissues was demonstrated. Subsequently, we revealed that FnEVs undergo membrane fusion with CRC cells, leading to the transfer and retention of FomA on recipient cell surfaces. Given its ability to facilitate F. nucleatum autoaggregation through interaction with FN1441, the presence of FomA on CRC cell surfaces presents a target for bacterial adhesion. Collectively, the findings unveil a mechanism used by EVs to prepare a niche conducive for bacterial colonization in distal organs.

Pharmacomicrobiomics in precision cancer therapy: bench to bedside

The burgeoning field of pharmacomicrobiomics offers promising insights into the intricate interplay between the microbiome and cancer, shaping responses to diverse treatment modalities. This review aims to analyze the molecular mechanisms underlying interactions between distinct microbiota types and cancer, as well as their influence on treatment outcomes. We explore how the microbiome impacts antitumor immunity, and response to chemotherapy, immunotherapy, and radiation therapy, unveiling its multifaceted roles in cancer progression and therapy resistance. Moreover, we discuss the challenges hindering the development of microbiome-based interventions in cancer therapy, including standardization, validation, and clinical translation. By synthesizing clinical evidence, we underscore the transformative potential of harnessing pharmacomicrobiomics in guiding cancer treatment decisions, paving the way for improved patient outcomes in clinical practice.

Salivary Microbiome Relates to Neoadjuvant Immunotherapy Response in OSCC

Most patients diagnosed with oral squamous cell carcinoma (OSCC) present with locally advanced stages, which are typically associated with poor outcomes. Although immunotherapy offers potential improvements in patient survival, its efficacy is hampered by low response rates. The microbiome is widely involved in tumor immunity and may play a role in immunotherapy. This study aimed to investigate the potential association between the oral (salivary) microbiome and immunotherapy response in patients with OSCC. Salivary metagenome sequencing was performed on 47 patients with OSCC undergoing neoadjuvant immunotherapy (NAIT) in a clinical trial (NCT04649476). Patients were divided into responders and nonresponders based on their pathological responses. The results showed that the species richness of the salivary microbiome was lower in the nonresponders before NAIT than in the responders. Differential analysis revealed that nonresponders exhibited a lower relative abundance of 34 bacterial species and a higher relative abundance of 4 bacterial species. Notably, low levels of Eubacterium infirmum, Actinobaculum, and Selenomas (EAS) in the saliva may be associated with the nonresponse of patients with OSCC to NAIT. A nomogram based on EAS was developed and validated to determine the efficacy of NAIT. The area under the curve for the training cohort was 0.81 (95% confidence interval, 0.66 to 0.81). Quantitative polymerase chain reaction confirmed that low levels of salivary EAS effectively identified nonresponders to NAIT. Furthermore, the low abundance of salivary EAS was closely correlated with a low density of intratumoral CD4+, CD14+, CD68+, and FOXP3+ cells. Metabolic functional annotation revealed numerous biosynthetic processes associated with EAS that were more active in responders. In summary, this study provides valuable data resources for the salivary microbiome and reveals that nonresponders have different salivary microbiome profiles than responders do before NAIT. Low salivary EAS levels can serve as potential biomarkers for distinguishing nonresponders from responders.

Circulating Bacterial DNA in Colorectal Cancer Patients: The Potential Role of Fusobacterium nucleatum

Intestinal dysbiosis is a major contributor to colorectal cancer (CRC) development, leading to bacterial translocation into the bloodstream. This study aimed to evaluate the presence of circulated bacterial DNA (cbDNA) in CRC patients (n = 75) and healthy individuals (n = 25). DNA extracted from peripheral blood was analyzed using PCR, with specific primers targeting 16S rRNA, Escherichia coli (E. coli), and Fusobacterium nucleatum (F. nucleatum). High 16S rRNA and E. coli detections were observed in all patients and controls. Only the detection of F. nucleatum was significantly higher in metastatic non-excised CRC, compared to controls (p < 0.001), non-metastatic excised CRC (p = 0.023), and metastatic excised CRC (p = 0.023). This effect was mainly attributed to the presence of the primary tumor (p = 0.006) but not the presence of distant metastases (p = 0.217). The association of cbDNA with other clinical parameters or co-morbidities was also evaluated, revealing a higher detection of E. coli in CRC patients with diabetes (p = 0.004). These results highlighted the importance of bacterial translocation in CRC patients and the potential role of F. nucleatum as an intratumoral oncomicrobe in CRC.

Unravelling the Oral-Gut Axis: Interconnection Between Periodontitis and Inflammatory Bowel Disease, Current Challenges, and Future Perspective

As the opposite ends of the orodigestive tract, the oral cavity and the intestine share anatomical, microbial, and immunological ties that have bidirectional health implications. A growing body of evidence suggests an interconnection between oral pathologies and inflammatory bowel disease [IBD], implying a shift from the traditional concept of independent diseases to a complex, reciprocal cycle. This review outlines the evidence supporting an 'oral-gut' axis, marked by a higher prevalence of periodontitis and other oral conditions in IBD patients and vice versa. We present an in-depth examination of the interconnection between oral pathologies and IBD, highlighting the shared microbiological and immunological pathways, and proposing a 'multi-hit' hypothesis in the pathogenesis of periodontitis-mediated intestinal inflammation. Furthermore, the review underscores the critical need for a collaborative approach between dentists and gastroenterologists to provide holistic oral-systemic healthcare.

Microbiota-Derived Extracellular Vesicle as Emerging Actors in Host Interactions

The human microbiota is an intricate micro-ecosystem comprising a diverse range of dynamic microbial populations mainly consisting of bacteria, whose interactions with hosts strongly affect several physiological and pathological processes. The gut microbiota is being increasingly recognized as a critical player in maintaining homeostasis, contributing to the main functions of the intestine and distal organs such as the brain. However, gut dysbiosis, characterized by composition and function alterations of microbiota with intestinal barrier dysfunction has been linked to the development and progression of several pathologies, including intestinal inflammatory diseases, systemic autoimmune diseases, such as rheumatic arthritis, and neurodegenerative diseases, such as Alzheimer's disease. Moreover, oral microbiota research has gained significant interest in recent years due to its potential impact on overall health. Emerging evidence on the role of microbiota-host interactions in health and disease has triggered a marked interest on the functional role of bacterial extracellular vesicles (BEVs) as mediators of inter-kingdom communication. Accumulating evidence reveals that BEVs mediate host interactions by transporting and delivering into host cells effector molecules that modulate host signaling pathways and cell processes, influencing health and disease. This review discusses the critical role of BEVs from the gut, lung, skin and oral cavity in the epithelium, immune system, and CNS interactions.

The profile of oral microbiome in Chinese elderly population associated with aging and systemic health status

OBJECTIVE

The health of oral cavity is considered as an important indicator of aging. Oral microbiota is highly associated with the oral health, while the variation of oral microbiome in elderly population and characteristic microbes associated with aging remain unclear.

SUBJECTS AND METHODS

In this study, 130 elderly subjects were recruited and divided into 3 groups according to their age: Stage I group (65 ≤ years < 70), Stage II group (70 ≤ years < 75), and Stage III group (75 ≤ years < 80). Their physiological indices were analyzed with using Illumina MiSeq platform and the oral microbiome was determined by high-throughput sequencing.

RESULTS

Along with aging, the level of fasting blood glucose, systolic pressure and monocytes are significantly increased. No significant difference was detected on the whole structure of the oral microbiome among groups. While using Metastats and Spearman's correlation analysis, specific bacteria were identified as potential age- or health index-related bacterial genera including Fusobacterium, Parvimonas, Porphyromonas, Aminobacter, Collinsella, Clostridium and Acinetobacter.

CONCLUSION

Our study revealed that the composition structure of salivary microbiota in elderly population was relatively stable while specific bacteria were correlated with age and health status, which is promising to be served as health indicators of the elderly after further exploration.

Relationship between human oral microbiome dysbiosis and neuropsychiatric diseases: An updated overview

The role of the gut-brain axis in mental health disorders has been extensively studied. As the oral cavity is the starting point of the digestive tract, the role that the oral microbiota plays in mental health disorders has gained recent attention. Oral microbiota can enter the bloodstream and trigger inflammatory responses or translocate to the brain through the trigeminal nerve or olfactory system. Hence, the concept of the oral microbiota-brain axis has emerged. Several hypotheses have been suggested that the oral microbiota can enter the gastrointestinal tract and affect the gut-brain axis; however, literature describing oral-brain communication remains limited. This review summarizes the characteristics of oral microbiota and its mechanisms associated with mental health disorders. Through a comprehensive examination of the relationship between oral microbiota and various neuropsychiatric diseases, such as anxiety, depression, schizophrenia, autism spectrum disorder, epilepsy, Parkinson's disease, and dementia, this review seeks to identify promising avenues of future research.

Research progress on the correlation between intestinal flora and colorectal cancer

Colorectal cancer (CRC) is one of the most common gastrointestinal malignancies in the world. With the rapid pace of life and changes in diet structure, the incidence and mortality of CRC increase year by year posing a serious threat to human health. As the most complex and largest microecosystem in the human body, intestinal microecology is closely related to CRC. It is an important factor that affects and participates in the occurrence and development of CRC. Advances in next-generation sequencing technology and metagenomics have provided new insights into the ecology of gut microbes. It also helps to link intestinal flora with CRC, and the relationship between intestinal flora and CRC can be continuously understood from different levels. This paper summarizes the relationship between intestinal flora and CRC and its potential role in the diagnosis of CRC providing evidence for early screening and treatment of CRC.

Tissue-resident bacteria in metabolic diseases: emerging evidence and challenges

Although the impact of the gut microbiome on health and disease is well established, there is controversy regarding the presence of microorganisms such as bacteria and their products in organs and tissues. However, recent contamination-aware findings of tissue-resident microbial signatures provide accumulating evidence in support of bacterial translocation in cardiometabolic disease. The latter provides a distinct paradigm for the link between microbial colonizers of mucosal surfaces and host metabolism. In this Perspective, we re-evaluate the concept of tissue-resident bacteria including their role in metabolic low-grade tissue and systemic inflammation. We examine the limitations and challenges associated with studying low bacterial biomass samples and propose experimental and analytical strategies to overcome these issues. Our Perspective aims to encourage further investigation of the mechanisms linking tissue-resident bacteria to host metabolism and their potentially actionable health implications for prevention and treatment.

Application of Fusobacterium nucleatum as a biomarker in gastrointestinal malignancies

The morbidity and mortality of gastrointestinal (GI) malignancies are among the highest in the world, posing a serious threat to human health. Because of the insidious onset of the cancer, it is difficult for patients to be diagnosed at an early stage, and it rapidly progresses to an advanced stage, resulting in poor treatment and prognosis. Fusobacterium nucleatum (F. nucleatum) is a gram-negative, spore-free anaerobic bacterium that primarily colonizes the oral cavity and is implicated in the development of colorectal, esophageal, gastric, and pancreatic cancers via various intricate mechanisms. Recent development in novel research suggests that F. nucleatum may function as a biomarker in GI malignancies. Detecting the abundance of F. nucleatum in stool, saliva, and serum samples of patients may aid in the diagnosis, risk assessment, and prognosis monitoring of GI malignancies. This editorial systematically describes the biological roles and mechanisms of F. nucleatum in GI malignancies focusing on the application of F. nucleatum as a biomarker in the diagnosis and prognosis of GI malignancies to promote the clinical translation of F. nucleatum and GI tumors-related research.

Linking periodontitis with 20 cancers, emphasis on oropharyngeal cancer: a Mendelian randomization analysis

While associations between periodontitis and an elevated risk of cancer have been suggested, the results of existing observational studies have been inconsistent, also leaving room for further investigation into the underlying mechanisms. This study was designed to delve into the possible causal link between periodontitis and 20 standard cancers while concurrently identifying potential mediators. We initiated a Mendelian randomization analysis that drew from either publicly accessible or personally obtained genome-wide association study (GWAS) datasets. The inverse variance weighting (IVW) method served as our primary tool for analysis. To ensure the strength and consistency of our results, we implemented additional strategies, including weighted median, weighted mode, MR-Egger regression, and MR pleiotropy residual sum and outlier (MR-PRESSO), bolstered by funnel plots. Our analysis unveiled an elevated risk of head and neck cancer concomitant with periodontitis (p = 0.041, OR 0.999, 95% CI 0.999-1.000), specifically a heightened risk of oropharyngeal cancer (p = 0.022, OR 0.999, 95% CI 0.999-1.000). As a result of probing into potential mediators, Fusobacterium nucleatum emerged as a likely intermediary in the promoting effect of periodontitis on oropharyngeal cancer (p = 0.021, OR 0.999, 95% CI 0.998-1.000). Inversely, basal cell carcinoma and endometrial cancer demonstrated an association with an increased incidence of periodontitis (basal cell carcinoma: p = 0.020, OR 0.987, 95% CI 0.976-0.998; endometrial cancer: p = 0.027, OR 0.984, 95% CI 0.970-0.998). However, periodontitis exerted no significant causal impact on the 19 other common cancers or the three subtypes of head and neck cancer. To conclude, our results support the theory that periodontitis contributes to an enhanced risk of head and neck cancer, particularly oropharyngeal cancer, with Fusobacterium nucleatum functioning as a potential intermediary.

A global survey of small RNA interactors identifies KhpA and KhpB as major RNA-binding proteins in Fusobacterium nucleatum

The common oral microbe Fusobacterium nucleatum has recently drawn attention after it was found to colonize tumors throughout the human body. Fusobacteria are also interesting study systems for bacterial RNA biology as these early-branching species encode many small noncoding RNAs (sRNAs) but lack homologs of the common RNA-binding proteins (RBPs) CsrA, Hfq and ProQ. To search for alternate sRNA-associated RBPs in F. nucleatum, we performed a systematic mass spectrometry analysis of proteins that co-purified with 19 different sRNAs. This approach revealed strong enrichment of the KH domain proteins KhpA and KhpB with nearly all tested sRNAs, including the σE-dependent sRNA FoxI, a regulator of several envelope proteins. KhpA/B act as a dimer to bind sRNAs with low micromolar affinity and influence the stability of several of their target transcripts. Transcriptome studies combined with biochemical and genetic analyses suggest that KhpA/B have several physiological functions, including being required for ethanolamine utilization. Our RBP search and the discovery of KhpA/B as major RBPs in F. nucleatum are important first steps in identifying key players of post-transcriptional control at the root of the bacterial phylogenetic tree.

Oral microbiota imbalance: A predisposing factor for Henoch-Schönlein Purpura in children

Oral microecological dysregulation has been shown to be associated with various immune system disorders. Henoch-schonlein purpura (HSP) is an autoimmune small vessel inflammatory disease in children of uncertain etiology, and studies have suggested that streptococcal infection may be an influential factor in its development. However, the relationship between oral microecological dysregulation and HSP has not been clearly studied so far. In this study, an epidemiological survey on the oral health status of children with HSP was investigated in this paper, and collected dental plaque from four groups of children for 16SrDNA high-throughput sequencing to analyze the composition and changes of oral microbial diversity among different groups. The results showed that the oral health status of children with HSP was poor, except for the incidence of caries in the 5-year-old group, the caries rate and dmfs/DMFS in the 3,4 and 5-year-old groups were higher than the same age in the fourth Chinese Oral Health Epidemiological Survey. Moreover, the development of HSP is accompanied by disturbances in the oral microbiota; a decrease in the number of Firmicutes which producing butyric acid may be closely associated with the development of HSP; changes in the abundance of Streptococcus and Neisseria may be a risk factor for the development of HSP.

Oral-to-rectum microbial transmission in orthopedic patients without a history of intestinal disorders

The enrichment of oral taxa in the gut has recently been reported as a notable alteration in the microbial balance in patients with intestinal disorders. However, translocation in populations without such diseases remains controversial. In this study, we examined 49 pairs of tongue and rectal samples collected from orthopedic patients without a history of intestinal disorders to verify the presence of oral taxa in the rectal microbiota. The bacterial composition of each sample was determined using 16S rRNA gene sequencing and amplicon sequence variant (ASV) analysis. Although the bacterial compositions of the tongue and rectal microbiota were distinctly different, tongue ASVs were detected in 67.3% of the participants and accounted for 0.0%-9.37% of the rectal microbiota. Particularly, Streptococcus salivarius, Fusobacterium nucleatum, and Streptococcus parasanguinis were abundant in the rectal microbiota. According to the network analysis, tongue taxa, such as S. salivarius and S. parasanguinis, formed a cohabiting group with Klebsiella pneumoniae and Alistipes finegoldii in the rectal microbiota. The total abundance of tongue ASVs in the rectal microbiota was significantly higher in participants with older age, hypertension, and proton pump inhibitor (PPI) use. Our study presents an extensive translocation of oral taxa to the rectum of a population without intestinal disorders and suggests that aging, hypertension, and PPI use are associated with an increased abundance of oral taxa and potential pathogenic bacteria in the rectal microbiota.

Stratification of Fusobacterium nucleatum by local health status in the oral cavity defines its subspecies disease association

The ubiquitous inflammophilic oral pathobiont Fusobacterium nucleatum (Fn) is widely recognized for its strong association with inflammatory dysbiotic diseases and cancer. Fn is subdivided into four subspecies, which are historically considered functionally interchangeable in the oral cavity. To test this assumption, we analyzed patient-matched dental plaque and odontogenic abscess clinical specimens and examined whether an inflammatory environment selects for/against particular Fn subspecies. Dental plaque harbored a greater diversity of fusobacteria, with Fn. polymorphum dominating, whereas odontogenic abscesses were exceptionally biased for the largely uncharacterized organism Fn. animalis. Comparative genomic analyses revealed significant genotypic distinctions among Fn subspecies that correlate with their preferred ecological niches and support a taxonomic reassignment of each as a distinct Fusobacterium species. Despite originating as a low-abundance organism in dental plaque, Fn. animalis typically outcompetes other oral fusobacteria within the inflammatory abscess environment, which may explain its prevalence in other oral and extraoral diseases.

Fusobacterium nucleatum subsp. animalis comes to the spotlight in oral diseases

Krieger et al.'s study in this issue of Cell Host & Microbe reveals that Fusobacterium nucleatum subsp. animalis strains, previously underestimated, are significant in disease-affected oral areas. This challenges the long-held notion of the dominance of Fusobacterium nucleatum subsp. nucleatum, reshaping our understanding of Fusobacterium distribution in the oral microbiome.

The microbial landscape of colorectal cancer

Colorectal cancer (CRC) is a substantial source of global morbidity and mortality in dire need of improved prevention and treatment strategies. As our understanding of CRC grows, it is becoming increasingly evident that the gut microbiota, consisting of trillions of microorganisms in direct interface with the colon, plays a substantial role in CRC development and progression. Understanding the roles that individual microorganisms and complex microbial communities play in CRC pathogenesis, along with their attendant mechanisms, will help yield novel preventive and therapeutic interventions for CRC. In this Review, we discuss recent evidence concerning global perturbations of the gut microbiota in CRC, associations of specific microorganisms with CRC, the underlying mechanisms by which microorganisms potentially drive CRC development and the roles of complex microbial communities in CRC pathogenesis. While our understanding of the relationship between the microbiota and CRC has improved in recent years, our findings highlight substantial gaps in current research that need to be filled before this knowledge can be used to the benefit of patients.

A distinct Fusobacterium nucleatum clade dominates the colorectal cancer niche

Fusobacterium nucleatum (Fn), a bacterium present in the human oral cavity and rarely found in the lower gastrointestinal tract of healthy individuals1, is enriched in human colorectal cancer (CRC) tumours2-5. High intratumoural Fn loads are associated with recurrence, metastases and poorer patient prognosis5-8. Here, to delineate Fn genetic factors facilitating tumour colonization, we generated closed genomes for 135 Fn strains; 80 oral strains from individuals without cancer and 55 unique cancer strains cultured from tumours from 51 patients with CRC. Pangenomic analyses identified 483 CRC-enriched genetic factors. Tumour-isolated strains predominantly belong to Fn subspecies animalis (Fna). However, genomic analyses reveal that Fna, considered a single subspecies, is instead composed of two distinct clades (Fna C1 and Fna C2). Of these, only Fna C2 dominates the CRC tumour niche. Inter-Fna analyses identified 195 Fna C2-associated genetic factors consistent with increased metabolic potential and colonization of the gastrointestinal tract. In support of this, Fna C2-treated mice had an increased number of intestinal adenomas and altered metabolites. Microbiome analysis of human tumour tissue from 116 patients with CRC demonstrated Fna C2 enrichment. Comparison of 62 paired specimens showed that only Fna C2 is tumour enriched compared to normal adjacent tissue. This was further supported by metagenomic analysis of stool samples from 627 patients with CRC and 619 healthy individuals. Collectively, our results identify the Fna clade bifurcation, show that specifically Fna C2 drives the reported Fn enrichment in human CRC and reveal the genetic underpinnings of pathoadaptation of Fna C2 to the CRC niche.

Effect of Periodontitis and Periodontal Therapy on Oral and Gut Microbiota

Mounting evidence indicates that periodontitis-related oral bacteria may contribute to gut microbial dysbiosis. This clinical study aimed to explore the oral-gut microbial signatures associated with periodontitis and to longitudinally evaluate the effect of periodontal treatment on the oral and gut microbial composition. Stool and saliva samples from generalized stage III/IV periodontitis patients (n = 47) were collected and analyzed by 16S ribosomal RNA gene amplicon sequencing, before and 3 mo after steps I to II of periodontal therapy. Periodontally healthy matched subjects (n = 47) were used as controls. Principal component analysis was carried out to identify oral-gut microbial profiles between periodontitis patients at baseline and healthy subjects; periodontitis samples were longitudinally compared before and after treatment. β-Diversity of gut microbial profiles of periodontitis patients before treatment significantly differed from healthy controls (P < 0.001). Periodontal therapy was associated with a significant change in gut microbiota (P < 0.001), with post-treatment microbial profiles similar to healthy volunteers. A higher abundance of Bacteroides, Faecalibacterium, Fusobacterium, and Lachnospiraceae was noted in fecal samples of periodontitis patients at baseline compared to healthy controls. In contrast, Lactobacillus was the only genus more abundant in the latter. Additionally, periodontal therapy led to a parallel reduction in the salivary carriage of periodontal pathobionts, as well as gut Bacteroides, Lachnoclostridium, Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae, to levels similar to healthy controls. Collectively, discriminating oral-gut microbial signatures of periodontitis were found. Periodontal treatment both mitigated oral dysbiosis and altered gut microbial composition, signifying potential broader implications for gastrointestinal health and disease.

A Review of the Use of Native and Engineered Probiotics for Colorectal Cancer Therapy

Colorectal cancer (CRC) is a serious global health concern, and researchers have been investigating different strategies to prevent, treat, or support conventional therapies for CRC. This review article comprehensively covers CRC therapy involving wild-type bacteria, including probiotics and oncolytic bacteria as well as genetically modified bacteria. Given the close relationship between CRC and the gut microbiota, it is crucial to compile and present a comprehensive overview of bacterial therapies used in the context of colorectal cancer. It is evident that the use of native and engineered probiotics for colorectal cancer therapy necessitates research focused on enhancing the therapeutic properties of probiotic strains.. Genetically engineered probiotics might be designed to produce particular molecules or to target cancer cells more effectively and cure CRC patients.

Ectopic colonization by oral bacteria as an emerging theme in health and disease

The number of research papers published on the involvement of the oral microbiota in systemic diseases has grown exponentially over the last 4 years clearly demonstrating the growing interest in this field. Indeed, accumulating evidence highlights the central role of ectopic colonization by oral bacteria in numerous noncommunicable diseases including inflammatory bowel diseases (IBDs), undernutrition, preterm birth, neurological diseases, liver diseases, lung diseases, heart diseases, or colonic cancer. There is thus much interest in understanding the molecular mechanisms that lead to the colonization and maintenance of ectopic oral bacteria. The aim of this review is to summarize and conceptualize the current knowledge about ectopic colonization by oral bacteria, highlight wherever possible the underlying molecular mechanisms and describe its implication in health and disease. The focus lies on the newly discovered molecular mechanisms, showcasing shared pathophysiological mechanisms across different body sites and syndromes and highlighting open questions in the field regarding the pathway from oral microbiota dysbiosis to noncommunicable diseases.

The Microbiome Matters: Its Impact on Cancer Development and Therapeutic Responses

In the evolving landscape of cancer research, the human microbiome emerges as a pivotal determinant reshaping our understanding of tumorigenesis and therapeutic responses. Advanced sequencing technologies have uncovered a vibrant microbial community not confined to the gut but thriving within tumor tissues. Comprising bacteria, viruses, and fungi, this diverse microbiota displays distinct signatures across various cancers, with most research primarily focusing on bacteria. The correlations between specific microbial taxa within different cancer types underscore their pivotal roles in driving tumorigenesis and influencing therapeutic responses, particularly in chemotherapy and immunotherapy. This review amalgamates recent discoveries, emphasizing the translocation of the oral microbiome to the gut as a potential marker for microbiome dysbiosis across diverse cancer types and delves into potential mechanisms contributing to cancer promotion. Furthermore, it highlights the adverse effects of the microbiome on cancer development while exploring its potential in fortifying strategies for cancer prevention and treatment.

Association between colorectal cancer, the frequency of Bacteroides fragilis, and the level of mismatch repair genes expression in the biopsy samples of Iranian patients

BACKGROUND

Deficient DNA mismatch repair (MMR) can cause microsatellite instability (MSI) and is more common in colorectal cancer (CRC) patients. Understanding the carcinogenic mechanism of bacteria and their impact on cancer cells is crucial. Bacteroides fragilis (B. fragilis) has been identified as a potential promoter of tumorigenesis through the alteration of signaling pathways. This study aims to assess the expression levels of msh2, msh6, mlh1, and the relative frequency of B. fragilis in biopsy samples from CRC patients.

MATERIALS AND METHODS

Based on the sequence of mlh1, msh2, and msh6 genes, B. fragilis specific 16srRNA and bacterial universal 16srRNA specific primers were selected, and the expression levels of the target genes were analyzed using the Real-Time PCR method.

RESULTS

Significant increases in the expression levels of mlh1, msh2, and msh6 genes were observed in the cancer group. Additionally, the expression of these MMR genes showed a significant elevation in samples positive for B. fragilis presence. The relative frequency of B. fragilis in the cancer group demonstrated a significant rise compared to the control group.

CONCLUSION

The findings suggest a potential correlation between the abundance of B. fragilis and alterations in the expression of MMR genes. Since these genes can play a role in modifying colon cancer, investigating microbial characteristics and gene expression changes in CRC could offer a viable solution for CRC diagnosis.

A bibliometric and visualized in oral microbiota and cancer research from 2013 to 2022

Numerous studies have highlighted the implication of oral microbiota in various cancers. However, no bibliometric analysis has been conducted on the relationship between oral microbiota and cancer. This bibliometric analysis aimed to identify the research hotspots in oral microbiota and cancer research, as well as predict future research trends. The literature published relating to oral microbiota and cancer was searched from the Web of Science Core Collection database (WoSCC) from 2013 to 2022. VOSviewer or Citespace software was used to perform the bibliometric analysis, focusing on countries, institutions, authors, journals, keywords and references. A total of 1516 publications were included in the analysis. The number of publications related oral microbiota and cancer increased annually, reaching its peak in 2022 with 287 papers. The United States (456) and China (370) were the countries with the most publications and made significant contributions to the field. Sears CL and Zhou XD were the most productive authors. The high frequency of keywords revealed key topics, including cancer (colorectal cancer, oral cancer), oral microbiota (Fusobacterium nucleatum, Porphyromonas gingivalis), and inflammation (periodontal disease). The latest trend keywords were F. nucleatum, dysbiosis, prognosis, tumor microenvironment, gastric microbiota, complications and survival, suggesting a new hotspot in the field of oral microbiota and cancer. Our study provides a comprehensive analysis of oral microbiota and cancer research, revealing an increase in publications in recent years. Future research directions will continue to focus on the diversity of oral microbiota impacted by cancers and the underlying mechanism connecting them, providing new ideas for targeted therapy of tumorigenesis.

Metagenomic analysis of oral and intestinal microbiome of patients during the initial stage of orthodontic treatment

INTRODUCTION

This prospective study analyzed changes in the oral and intestinal microbiomes in patients before and after fixed orthodontic treatment, elucidating the impacts of fixed orthodontic treatment on patient health and metabolism.

METHODS

Metagenomic analysis was conducted on stool, dental plaque, and saliva samples from 10 fixed orthodontic patients. All the samples were sequenced with Illumina NovaSeq 6000 with a paired-end sequencing length of 150 bp. Identification of taxa in metagenomes and functional annotation of genes of the microbiota were performed using the data after quality control. Clinical periodontal parameters, including the gingiva index, plaque index, and pocket probing depth, were examined at each time point in triplicates. Patients also received a table to record their oral hygiene habits of brushing, flossing, and dessert consumption frequency over 1 month.

RESULTS

The brushing and flossing times per day of patients were significantly increased after treatment compared with baseline. The number of times a patient ate dessert daily was also fewer after treatment than at baseline. In addition, the plaque index decreased significantly, whereas the pH value of saliva, gingiva index, and pocket probing depth did not change. No significant differences were observed between the participants before and after orthodontic treatment regarding alpha-diversity analysis of the gut, dental plaque, or saliva microbiota. However, on closer analysis, periodontal disease-associated bacteria levels in the oral cavity remain elevated. Alterations in gut microbiota were also observed after orthodontic treatment.

CONCLUSIONS

The richness and diversity of the microbiome did not change significantly during the initial stage of fixed orthodontic treatment. However, the levels of periodontal disease-associated bacteria increased.

Exploring the oral-gut linkage: Interrelationship between oral and systemic diseases

The oral cavity harbors a diverse microbiota that plays a significant role in maintaining homeostasis. Disruption of this balance can lead to various oral diseases, including periodontitis. Accumulating evidence suggests a connection between periodontitis and extra-oral diseases such as cardiovascular disease, rheumatoid arthritis, obesity, and diabetes. During periodontitis, oral bacteria enter the bloodstream directly, impacting extra-oral organs. Furthermore, recent studies have uncovered another pathway, the direct oral-gut axis, where oral bacteria translocate to the gut through an enteral route, influencing gut microbiota and metabolism. Oral pathobionts associated with exacerbation of periodontal disease are implicated in gut pathology, including inflammatory bowel disease and colorectal cancer through ectopic gut colonization. Furthermore, oral bacteria can provoke host immune responses, leading to colitis and other inflammatory diseases. Conversely, mechanisms by which extra-oral conditions exacerbate oral diseases, such as periodontitis, are also beginning to be elucidated. This review discusses the bidirectional interrelationship between oral and systemic diseases based on the oral-gut linkage.