Oral Bacteria and Intestinal Dysbiosis in Colorectal Cancer

Dynamics of the oral microbiome during orthodontic treatment and antimicrobial advances for orthodontic appliances

The oral microbiome plays an important role in human health, and an imbalance of the oral microbiome could lead to oral and systemic diseases. Orthodontic treatment is an effective method to correct malocclusion. However, it is associated with many adverse effects, including white spot lesions, caries, gingivitis, periodontitis, halitosis, and even some systematic diseases. Undoubtedly, increased difficulty in oral hygiene maintenance and oral microbial disturbances are the main factors in developing these adverse effects. The present article briefly illustrates the characteristics of different ecological niches (including saliva, soft tissue surfaces of the oral mucosa, and hard tissue surfaces of the teeth) inhabited by oral microorganisms. According to the investigations conducted since 2014, we comprehensively elucidate the alterations of the oral microbiome in saliva, dental plaque, and other ecological niches after the introduction of orthodontic appliances. Finally, we provide a detailed review of recent advances in the antimicrobial properties of different orthodontic appliances. This article will provide researchers with a profound understanding of the underlying mechanisms of the effects of orthodontic appliances on human health and provide direction for further research on the antimicrobial properties of orthodontic appliances.

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 cancer and its implications for clinical applications

Fusobacterium nucleatum, a gram-negative anaerobic bacterium abundantly found in the human oral cavity, is widely recognized as a key pathobiont responsible for the initiation and progression of periodontal diseases due to its remarkable aggregative capabilities. Numerous clinical studies have linked F. nucleatum with unfavorable prognostic outcomes in various malignancies. In further research, scholars have partially elucidated the mechanisms underlying F. nucleatum's impact on various types of cancer, thus gaining a certain comprehension of the role played by F. nucleatum in cancer. In this comprehensive review, we present an in-depth synthesis of the interplay between F. nucleatum and different cancers, focusing on aspects such as tumor initiation, metastasis, chemoresistance, and modulation of the tumor immune microenvironment and immunotherapy. The implications for cancer diagnosis and treatment are also summarized. The objective of this review is to enhance our comprehension of the intricate relationship between F. nucleatum and oncogenic pathogenesis, while emphasizing potential therapeutic strategies.

Biopolymer-based oral films integrated with probiotic active compounds for improved health applications

Orally dissolving films (ODFs) have emerged as a versatile platform that combines convenience, efficacy, and patient compliance. In this study, the cell-free supernatant of the oral probiotic Streptococcus salivarius M18 was incorporated into various biopolymer-based ODF formulations, evaluated for demolding, fragility, and flexibility. The combination of carboxymethyl cellulose, sodium alginate, and glycerol successfully formed stable films. The films were characterized by weight, thickness, pH, and disintegration times. Fourier-transform infrared spectroscopy (FTIR) was used to analyze ODF content and release profiles in simulated saliva. Unique absorption peaks in the cell-free product-incorporated ODF samples confirmed the integration of bacterial proteins, lipids, and nucleic acids into the ODF matrix. The biological activity of the ODF carrying M18 bioactive products was assessed by its inhibitory effect on the growth of Streptococcus mutans, a pathogen linked to dental plaque and cavities. Additionally, the anti-proliferative effect on cancer epithelial cells was demonstrated. This study show that probiotic products can be integrated into bio-based thin films without losing activity, making this delivery platform promising for local and potentially systemic effects.

Exploring the role of Fusobacterium nucleatum in colorectal cancer: implications for tumor proliferation and chemoresistance

Fusobacterium nucleatum (Fn) has been extensively studied for its connection to colorectal cancer (CRC) and its potential role in chemotherapy resistance. Studies indicate that Fn is commonly found in CRC tissues and is associated with unfavorable prognosis and treatment failure. It has been shown that Fn promotes chemoresistance by affecting autophagy, a cellular process that helps cells survive under stressful conditions. Additionally, Fn targets specific signaling pathways that activate particular microRNAs and modulate the response to chemotherapy. Understanding the current molecular mechanisms and investigating the importance of Fn-inducing chemoresistance could provide valuable insights for developing novel therapies. This review surveys the role of Fn in tumor proliferation, metastasis, and chemoresistance in CRC, focusing on its effects on the tumor microenvironment, gene expression, and resistance to conventional chemotherapy drugs. It also discusses the therapeutic implications of targeting Fn in CRC treatment and highlights the need for further research.

Evaluation of Periodontitis and Fusobacterium nucleatum Among Colorectal Cancer Patients: An Observational Cross-Sectional Study

BACKGROUND

Periodontitis has been associated with an increased risk of CRC, as well as a worse prognosis due to increased inflammation mediators and carcinogenic factors. Moreover, direct and indirect virulence factors from periodontal pathogens, such as Fusobacterium nucleatum, could play a pivotal role in malignant transformation and progression. This cross-sectional study aims to evaluate the presence and the stage of periodontitis in a cohort of patients with CRC. The secondary aim is to assess the presence of F. nucleatum and its relationship with patients' general characteristics, concomitant pathologies, tumor characteristics, and drug therapy.

MATERIALS AND METHODS

Patients affected by CRC underwent dental examination and periodontal charting with the "North Carolina" probe to assess the presence and stage of periodontitis, according to the new classification of periodontal diseases of the World Workshop of the European Federation of Periodontology (EFP) and the American Academy of Periodontology (AAP) 2017. F. nucleatum presence was assessed by a dorsal tongue swab and related to the patient's general characteristics, concomitant pathologies, tumor characteristics, and drug therapy.

RESULTS

Periodontal disease was found in 94.3% of I/II CRC stage patients and 100% of III/IV CRC stage patients. Severe periodontitis was found in 76% of the advanced CRC stage and 87.9% of patients with initial CRC, while initial periodontitis was found in 12.1% of initial CRC and 24% of late CRC stages, respectively, without significant differences. F. nucleatum presence showed no correlation between the patient's and tumor's characteristics, comorbidities, and drug assumed.

CONCLUSIONS

Periodontal disease showed a high prevalence among CRC patients. Moreover, severe periodontitis has a higher prevalence in CRC patients compared to initial periodontitis. F. nucleatum presence was unrelated to CRC stage, site, other comorbidities, and drug therapies. With these data, it is not possible to admit a direct relationship between CRC and periodontal disease, but further case-control studies must be carried out to further prove this aspect. Preventive and operative targeted strategies to maintain a healthy oral status are suggested in CRC patients.

Number of Healthy Teeth Can Predict the Response of Rectal Cancer to Chemoradiotherapy: A Retrospective Study

BACKGROUND

It has been reported that the oral and gut microbiomes are associated with the prognosis in patients who undergo surgery, chemotherapy, and radiation for colorectal cancer. This study is the first to identify a correlation between the number of healthy teeth, which is an oral health indicator, and the efficacy of preoperative chemotherapy for rectal cancer.

METHODS

This retrospective single-center study included 30 patients who underwent radical surgery after preoperative chemoradiotherapy (CRT) between December 2013 and June 2021. The relationship between number of teeth before CRT and the efficacy of CRT, CRT-related adverse events, postoperative complications, and long-term postoperative outcomes was examined.

RESULTS

The number of healthy teeth was significantly greater in patients with downstaging of their disease than in those without downstaging (P = .027) and in patients with a complete response according to the Response Evaluation Criteria in Solid Tumors than in those who did not have a complete response (P = .014). Patients were divided into two groups according to whether they had ≥15 teeth or ≤14 teeth. There was no significant between-group difference in CRT-related adverse events. The incidence of all postoperative complications and grade II postoperative complications tended to be higher in patients with ≥15 teeth (P = .071 and P = .092, respectively), as did the 5-year overall survival rate (P = .083) and the 5-year disease-free rate (P = .007).

DISCUSSION

The number of healthy teeth predicted the response to preoperative CRT, postoperative complications, and the outcome of subsequent surgery in patients with rectal cancer.

Physical activity, sedentary behavior and microbiome: A systematic review and meta-analysis

BACKGROUND

The effects of physical activity and sedentary behavior on human health are well known, however, the molecular mechanisms are poorly understood. Growing evidence points to physical activity as an important modulator of the composition and function of microbial communities, while evidence of sedentary behavior is scarce. We aimed to synthesize and meta-analyze the current evidence about the effects of physical activity and sedentary behavior on microbiome across different body sites and in different populations.

METHODS

A systematic search in PubMed, Web of Science, Scopus and Cochrane databases was conducted until September 2022. Random-effects meta-analyses including cross-sectional studies (active vs. inactive/athletes vs. non-athletes) or trials reporting the chronic effect of physical activity interventions on gut microbiome alpha-diversity in healthy individuals were performed.

RESULTS

Ninety-one studies were included in this systematic review. Our meta-analyses of 2632 participants indicated no consistent effect of physical activity on microbial alpha-diversity, although there seems to be a trend toward a higher microbial richness in athletes compared to non-athletes. Most of studies reported an increase in short-chain fatty acid-producing bacteria such as Akkermansia, Faecalibacterium, Veillonella or Roseburia in active individuals and after physical activity interventions.

CONCLUSIONS

Physical activity levels were positively associated with the relative abundance of short-chain fatty acid-producing bacteria. Athletes seem to have a richer microbiome compared to non-athletes. However, high heterogeneity between studies avoids obtaining conclusive information on the role of physical activity in microbial composition. Future multi-omics studies would enhance our understanding of the molecular effects of physical activity and sedentary behavior on the microbiome.

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.

Assessing the oral microbiome of head and neck cancer patients before and during radiotherapy

OBJECTIVE

To characterize the oral microbiome of patients with head and neck squamous cell carcinoma (HNSCC) before and during radiotherapy (RT), compared to healthy individuals. Evaluating the impact of oral microbiome in the clinical outcomes one year following the end of RT.

METHODS

Oral samples were collected from HNSCC patients who underwent RT using the following regimens: no dose received (T0), dose 12-16 Gy (T1), dose 30-36 Gy (T2) and dose ≥ 60 Gy (T3). Samples from healthy individuals were also collected only once as a control group. Regions V1-V2 of the 16S rRNA were sequenced by Illumina and analyzed using Mothur.

RESULTS

49 patients with HNSCC and 25 healthy individuals were included. At T0, HNSCC patients showed a lower abundance of Firmicutes and Streptococcus (p = 0.011, p = 0.002) and a higher abundance of Bacteroidetes (p = 0.005) compared to healthy individuals. During RT, Fusobacterium (p = 0.017) and Porphyromonas (p = 0.0008) decreased, while Streptococcus increased at T1 (p = 0.001). By T3, the differences in Firmicutes, Bacteroidetes, and Streptococcus between the control and HNSCC groups were no longer significant (p > 0.3). Patients with higher initial abundances of Porphyromonas (p = 0.012) and Fusobacterium (p = 0.017) had poorer outcomes, including recurrence, metastasis, and death. In contrast, disease-free patients had a higher abundance of Streptococcus (p = 0.004).

CONCLUSION

Oral microbiome dysbiosis was found in HNSCC patients. By the end of RT, the main initial differences in phylum and genus abundance observed at T0 between the control and HNSCC groups were no longer present. Higher abundances of Fusobacterium and Porphyromonas were associated with poor outcomes.

From colon wall to tumor niche: Unraveling the microbiome's role in colorectal cancer progression

Colorectal cancer (CRC) is influenced by perturbations in the colonic microbiota, characterized by an imbalance favoring pathogenic bacteria over beneficial ones. This dysbiosis contributes to CRC initiation and progression through mechanisms such as carcinogenic metabolite production, inflammation induction, DNA damage, and oncogenic signaling activation. Understanding the role of external factors in shaping the colonic microbiota is crucial for mitigating CRC progression. This study aims to elucidate the gut microbiome's role in CRC progression by analyzing paired tumor and mucosal tissue samples obtained from the colon walls of 17 patients. Through sequencing of the V3-V4 region of the 16S rRNA gene, we characterized the tumor microbiome and assessed its association with clinical variables. Our findings revealed a significant reduction in alpha diversity within tumor samples compared to paired colon biopsy samples, indicating a less diverse microbial environment within the tumor microenvironment. While both tissues exhibited dominance of similar bacterial phyla, their relative abundances varied, suggesting potential colon-specific effects. Fusobacteriota enrichment, notably in the right colon, may be linked to MLH1 deficiency. Taxonomy analysis identified diverse bacterial genera, with some primarily associated with the colon wall and others unique to this region. Conversely, several genera were exclusively expressed in tumor tissue. Functional biomarker analysis identified three key genes with differential abundance between tumor microenvironment and colon tissue, indicating distinct metabolic activities. Functional biomarker analysis revealed three key genes with differential abundance: K11076 (putrescine transport system) and K10535 (nitrification) were enriched in the tumor microenvironment, while K11329 (SasA-RpaAB circadian timing mediator) dominated colon tissue. Metabolic pathway analysis linked seven metabolic pathways to the microbiome. Collectively, these findings highlight significant gut microbiome alterations in CRC and strongly suggest that long-term dysbiosis profoundly impacts CRC progression.

Intestinal homeostasis disrupted by Periodontitis exacerbates Alzheimer's Disease in APP/PS1 mice

Periodontitis exacerbates Alzheimer's disease (AD) through multiple pathways. Both periodontitis and AD are intricately correlated to intestinal homeostasis, yet there is still a lack of direct evidence regarding whether periodontitis can regulate the progression of AD by modulating intestinal homeostasis. The current study induced experimental periodontitis in AD mice by bilaterally ligating the maxillary second molars with silk and administering Pg-LPS injections in APPswe/PS1ΔE9 (APP/PS1) mice. Behavioral tests and histological analyses of brain tissue were conducted after 8 weeks. Gut microbiota was analyzed and colon tissue were also evaluated. Then, fecal microbiota from mice with periodontitis was transplanted into antibiotic-treated mice to confirm the effects of periodontitis on AD and the potential mechanism was explored. The results indicated periodontitis exacerbated cognitive impairment and anxious behaviour in APP/PS1 mice, with increased Aβ deposition, microglial overactivation and neuroinflammation in brain. Moreover, the intestinal homeostasis of AD mice was altered by periodontitis, including affecting gut microbiota composition, causing colon inflammation and destroyed intestinal epithelial barrier. Furthermore, AD mice that underwent fecal transplantation from mice with periodontitis exhibited worsened AD progression and disrupted intestinal homeostasis. It also impaired intestinal barrier function, elevated peripheral inflammation, damaged blood-brain barrier (BBB) and caused neuroinflammation and synapses impairment. Taken together, the current study demonstrated that periodontitis could disrupt intestinal homeostasis to exacerbate AD progression potential via causing gut microbial dysbiosis, intestinal inflammation and intestinal barrier impairment to induce peripheral inflammation and damage BBB, ultimately leading to neuroinflammation and synapse impairment. It underscores the importance of maintaining both periodontal health and intestinal homeostasis to reduce the risk of AD.

Oral Microbial Translocation Genes in Gastrointestinal Cancers: Insights from Metagenomic Analysis

Along with affecting oral health, oral microbial communities may also be endogenously translocated to the gut, thereby mediating the development of a range of malignancies in that habitat. While species-level studies have proven the capability of oral pathogens to migrate to the intestine, genetic evidence supporting this mechanism remains insufficient. In this study, we identified over 55,000 oral translocation genes (OTGs) associated with colorectal cancer (CRC) and inflammatory bowel disease (IBD). These genes are primarily involved in signal transduction and cell wall biosynthesis and show consistency in their functions between IBD and CRC. Furthermore, we found that Leclercia adecarboxylata, a newly discovered opportunistic pathogen, has a significantly high abundance in the gut microbiota of colorectal cancer patients. OTGs of this pathogen were enriched in 15 metabolic pathways, including those associated with amino acid and cofactor metabolism. These findings, for the first time, provide evidence at the genetic level of the transfer of oral pathogens to the intestine and offer new insights into the understanding of the roles of oral pathogens in the development of gastrointestinal cancers.

Exploring the gut microbiome's role in colorectal cancer: diagnostic and prognostic implications

The intricate interplay between the gut microbiome and colorectal cancer (CRC) presents novel avenues for early diagnosis and prognosis, crucial for improving patient outcomes. This comprehensive review synthesizes current findings on the gut microbiome's contribution to CRC pathogenesis, highlighting its potential as a biomarker for non-invasive CRC screening strategies. We explore the mechanisms through which the microbiome influences CRC, including its roles in inflammation, metabolism, and immune response modulation. Furthermore, we assess the viability of microbial signatures as predictive tools for CRC prognosis, offering insights into personalized treatment approaches. Our analysis underscores the necessity for advanced metagenomic studies to elucidate the complex microbiome-CRC nexus, aiming to refine diagnostic accuracy and prognostic assessment in clinical settings. This review propels forward the understanding of the microbiome's diagnostic and prognostic capabilities, paving the way for microbiome-based interventions in CRC management.

Proton Pump Inhibitors and Oral-Gut Microbiota: From Mechanism to Clinical Significance

Proton pump inhibitors (PPIs) are some of the most commonly prescribed drugs worldwide, but there are increasing concerns about digestive complications linked to PPIs. Next-generation sequencing studies have suggested that PPIs can significantly affect the composition of the gut microbiota, which in turn may substantially contribute to the development of these complications. Recently, emerging evidence has suggested that the translocation of oral microbes into the gut may be the primary mechanism underlying the alterations in the gut microbiota induced by PPIs in the presence of gastric acid suppression and impaired oral-gut barrier function. Moreover, the significance of oral-gut microbial translocation in health and disease conditions has gained increasing recognition. Consequently, it is imperative to enhance our understanding of the functions of the oral-gut microbiota axis in digestive disorders associated with PPI therapies. This review aims to summarize current research findings and further elucidate the contribution of the oral-gut microbiota to the pathogenesis of PPI-related digestive diseases. We aim to provide a theoretical foundation for future therapeutic and preventive strategies targeting PPI-related digestive complications through modulation of the oral-gut microbiota.

Guideline for designing microbiome studies in neoplastic diseases

Oncobiosis has emerged as a key contributor to the development, and modulator of the treatment efficacy of cancer. Hereby, we review the modalities through which the oncobiome can support the progression of tumors, and the emerging therapeutic opportunities they present. The review highlights the inherent challenges and limitations faced in sampling and accurately characterizing oncobiome. Additionally, the review underscores the critical need for the standardization of microbial analysis techniques and the consistent reporting of microbiome data. We provide a suggested metadata set that should accompany microbiome datasets from oncological settings so that studies remain comparable and decipherable.

[The human microbiome proofed by the Anthropocene: from correlation to causality and intervention]

The deleterious effects of human activities on biodiversity in the vegetal and animal world, and on climate changes are now well-established facts. However, little is yet known on the impact of human activities on microbial diversity on the planet and more specifically on the human microbiota Large implementation of metagenomics allows exaustive microbial cataloguing with broad spatio-temporal resolution of human microbiota. A reduction in bacterial richness and diversity in the human microbiota, particularly in the intestinal tract, is now established and particularly obvious in the most industrialized regions of the planet. Massive, uncontrolled use of antibiotics, drastic changes in traditional food habits and some elements of the "global exposome" that remain to identify are usually considered as stressors accounting for this situation of "missing microbes". As a consequence, a dysbiotic situation develops, a "dysbiosis" being characterized by the erosion of the central core of shared bacterial species across individuals and the development of opportunistic "pathobionts" in response to a weaker barrier capacity of these impoverished microbiota. The current challenge is to establish a causality link between the extension of these dysbiotic situations and the steady emergence of epidemic, non-communicable diseases such as asthma, allergy, obesity, diabetes, autoimmune diseases and some cancers. Experimental animal models combined with controlled, prospective clinical interventions are in demand to consolidate causality links, with the understanding that in the deciphering of the mechanisms of alteration of the human-microbiome symbiosis resides a novel exciting chapter of medicine: "microbial medicine".

Gut commensal Alistipes as a potential pathogenic factor in colorectal cancer

Although previous research has shown that inflammation is associated with development of colorectal cancer (CRC), questions remain about whether inflammatory factor-secreting bacteria play a crucial role in CRC development. The potential role of gut microbiota in secreting inflammatory factors involved in the carcinogenesis of CRC among Chinese patients was explored in this study. 16S rRNA sequencing was utilized to evaluate the distinct microbial characteristics between patients with CRC and colorectal adenoma. The serum levels of TNF-α, IL-6 and IL-10 were measured using Enzyme-linked immunosorbent assay (ELISA), while the expression of LRG1 and TGF-β1 in tissues was evaluated by immunohistochemistry. The correlation between gut microbiota and inflammatory factor signaling was analyzed. Compared with the adenoma group, CRC patients exhibit distinct pathologies. Moreover, elevated levels of CEA, erythrocytes and haemoglobin in the blood of CRC patients were found. In addition, CRC patients have significantly higher levels of TNF-α, IL-6, IL-10, LRG1 and TGF-β1. Spearman correlation analysis revealed that LRG1 was positively related to IL-6 and TNF-α, respectively. The correlation analysis results of TGF-β1 were consistent with the above. The abundance of Blautia and Streptococcus was lower in CRC patients, while the relative abundance of Alistipes, Peptostreptococcus and Porphyromonas was significantly elevated. Moreover, positive correlations between Alistipes and inflammatory factor signaling were also found. Our results suggest that gut commensal Alistipes is a key bacterium with pro-inflammatory properties in the CRC carcinogenesis. TNF-α and IL-6 associated with Alistipes might activate LRG1/TGF-β1 signaling which contributed to the carcinogenesis of CRC.

From pathogenesis to treatment: the impact of bacteria on cancer

The intricate relationship between cancer and bacteria has garnered increasing attention in recent years. While traditional cancer research has primarily focused on tumor cells and genetic mutations, emerging evidence highlights the significant role of microbial communities within the tumor microenvironment in cancer development and progression. This review aims to provide a comprehensive overview of the current understanding of the complex interplay between cancer and bacteria. We explore the diverse ways in which bacteria influence tumorigenesis and tumor behavior, discussing direct interactions between bacteria and tumor cells, their impact on tumor immunity, and the potential modulation of the tumor microenvironment. Additionally, we delve into the mechanisms through which bacterial metabolites and extracellular products May affect cancer pathways. By conducting a thorough analysis of the existing literature, we underscore the multifaceted and intricate relationship between bacteria and cancer. Understanding this complex interplay could pave the way for novel therapeutic approaches and preventive strategies in cancer treatment.

Unveiling the hidden link between oral flora and colorectal cancer: a bidirectional Mendelian randomization analysis and meta-analysis

Objective

The impact of oral flora on intestinal micro-environment and related diseases has been widely reported, but its role in colorectal cancer (CRC) remains elusive.

Methods

A Two-sample Mendelian Randomization (TSMR) analysis was conducted to explore the causal relationship between oral flora and CRC, with the Inverse-Variance Weighted (IVW) serving as the primary method for evaluating this causal relationship. Data on the oral flora were derived from human samples from the tongue and saliva, with all cohort populations originating from Asia. In addition, 2 independent external cohorts were used to validate the positive results and perform a meta-analysis of the final results. Lastly, to balance the effect of positive oral flora on CRC, a Multivariate Mendelian Randomization (MVMR) analysis was also performed.

Results

The TSMR analysis revealed that 17 oral flora may have a causal relationship with CRC in the training cohort. Among them, s Haemophilus, g Fusobacterium, s Metamycoplasma salivarium, and s Mogibacterium pumilum were validated in two testing cohorts. Intriguingly, after integrating the results of the 3 cohorts for meta-analysis, 16 associations remained significant. In the training cohort, MVMR analysis demonstrated that s Capnocytophaga ochracea and s Metamycoplasma salivarium retained statistical significance. In one of the testing cohorts, s Metamycoplasma salivarium, s Streptococcus anginosus, and s Streptococcus sanguinis retained statistical significance. In the other testing cohort, s Metamycoplasma salivarium, s Haemophilus, and g Fusobacterium remained significant.

Conclusion

s Haemophilus, g Fusobacterium, s Metamycoplasma salivarium, and s Mogibacterium pumilum have a solid causal relationship with the occurrence and development of CRC.

Influence of microbiome in intraprostatic inflammation and prostate cancer

BACKGROUND

Chronic infection and inflammation have been linked to the development of prostate cancer. Dysbiosis of the oral and gut microbiomes and subsequent microbial translocation can lead to pathogenic prostate infections. Microbial-produced metabolites have also been associated with signaling pathways that promote prostate cancer development. A comprehensive discussion on the mechanisms of microbiome infection and the prostate microenvironment is essential to understand prostate carcinogenesis.

METHODS

Published studies were used from the National Center for Biotechnology Information (NCBI) database to conduct a narrative review. No restrictions were applied in the selection of articles.

RESULTS

Microbiome-derived short-chain fatty acids (SCFAs) have been found to upregulate multiple signaling pathways, including MAPK and PI3K, through IGF-1 signaling and M2 macrophage polarization. SCFAs can also upregulate Toll-like receptors, leading to chronic inflammation and the creation of a pro-prostate cancer environment. Dysbiosis of oral microbiota has been correlated with prostate infection and inflammation. Additionally, pathogenic microbiomes associated with urinary tract infections have shown a link to prostate cancer, with vesicoureteral reflux potentially contributing to prostate infection.

CONCLUSIONS

This review offers a comprehensive understanding of the impact of microbial infections linked to intraprostatic inflammation as a causative factor for prostate cancer. Further studies involving the manipulation of the microbiome and its produced metabolites may provide a more complete understanding of the microenvironmental mechanisms that promote prostate carcinogenesis.

Ecosystemic Approach to Understanding Gut Microbiome-Mediated Prevention of Colorectal Cancer

Humans and their associated microorganisms coexist in complex symbiotic relationships. Continuously advancing research is demonstrating the crucial role of host-associated microbiota in the pathophysiology and etiology of disease and in mediating the prevention thereof. As an exemplar, the gut microbiota, especially colonic bacteria, have been extensively studied in colorectal cancer (CRC), and the growing body of evidence establishes new oncomicrobes and their oncometabolites associated with the initiation and promotion of carcinogenesis. Herein, we discuss the importance of approaching the gut microbiome as an ecosystem rather than an assortment of individual factors, especially in the context of cancer prevention. Furthermore, we argue that a dietary pattern effectively drives multiple nodes of the gut microbial ecosystem toward disease- or health-promoting qualities. In the modern circumstances of excessive consumption of ultraprocessed and animal-based foods and concomitant escalation of chronic disease burden worldwide, we focus on whole food-derived dietary fiber as a key to establishing a health-promoting eubiosis in the gut.

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.

Obesity and periodontitis: a comprehensive review of their interconnected pathophysiology and clinical implications

Obesity and periodontitis are significant health problems with a complex bidirectional relationship. Excess body fat is linked to systemic diseases and can lead to persistent inflammation, potentially harming periodontal health. Periodontitis, a chronic inflammatory condition affecting the supporting structures of teeth, poses substantial health risks. Both conditions share pathological processes such as inflammation and oxidative stress, which aggravate health status and make treatment more challenging. Understanding this interaction is crucial for developing effective management strategies for both diseases. This study explores the multifaceted aspects of obesity and periodontitis and their reciprocal relationship.

Emergence of rare and low abundant anaerobic gut Firmicutes is associated with a significant downfall of Klebsiella in human colon cancer

Gut bacterial dysbiosis has been linked to several gastrointestinal diseases, including deadly colorectal cancer (CRC), a leading cause of mortality in cancer patients. However, perturbation in gut bacteriome during colon cancer (CC, devoid of colorectal malignancy) remains poorly explored. Here, 16S rRNA gene amplicon sequencing was carried out for fecal DNA samples targeted to hypervariable V3-V4 region by employing MiSeq platform to explore the gut bacterial community shift in CC patients. While alpha diversity indices predicted high species richness and diversity, beta diversity showed marked gut bacterial compositional dissimilarity in CC versus healthy controls (HC, n = 10 each). We observed a significant (p < 0.05, Wilcoxon Rank-Sum test) emergence of low-abundant anaerobic taxa, including Parvimonas and Peptostreptococcus, in addition to Subdoligranulum, Coprococcus, Holdemanella, Solobacterium, Bilophila, Blautia, Dorea, Moryella and several unidentified taxa, mainly affiliated to Firmicutes, in CC patients. In addition, we also traced the emergence of putative probiotic taxon Slackia, belonging to Actinomycetota, in CC patients. The emergence of anaerobic Firmicutes in CC is accompanied by a significant (p < 0.05) decline in the Klebsiella, as determined through linear discriminant analysis effect size (LEfSe) and heat tree analyses. Shifts in core microbiome and variation in network correlation were also witnessed. Taken together, this study highlighted a significant and consistent emergence of rare anaerobic Firmicutes suggesting possible anaerobiosis driving gut microbial community shift, which could be exploited in designing diagnostic and therapeutic tools targeted to CC.

The role of periodontitis in cancer development, with a focus on oral cancers

Periodontitis is a severe gum infection that begins as gingivitis and can lead to gum recession, bone loss, and tooth loss if left untreated. It is primarily caused by bacterial infection, which triggers inflammation and the formation of periodontal pockets. Notably, periodontitis is associated with systemic health issues and has been linked to heart disease, diabetes, respiratory diseases, adverse pregnancy outcomes, and cancers. Accordingly, the presence of chronic inflammation and immune system dysregulation in individuals with periodontitis significantly contributes to the initiation and progression of various cancers, particularly oral cancers. These processes promote genetic mutations, impair DNA repair mechanisms, and create a tumor-supportive environment. Moreover, the bacteria associated with periodontitis produce harmful byproducts and toxins that directly damage the DNA within oral cells, exacerbating cancer development. In addition, chronic inflammation not only stimulates cell proliferation but also inhibits apoptosis, causes DNA damage, and triggers the release of pro-inflammatory cytokines. Collectively, these factors play a crucial role in the progression of cancer in individuals affected by periodontitis. Further, specific viral and bacterial agents, such as hepatitis B and C viruses, human papillomavirus (HPV), Helicobacter pylori (H. pylori), and Porphyromonas gingivalis, contribute to cancer development through distinct mechanisms. Bacterial infections have systemic implications for cancer development, while viral infections provoke immune and inflammatory responses that can lead to genetic mutations. This review will elucidate the link between periodontitis and cancers, particularly oral cancers, exploring their underlying mechanisms to provide insights for future research and treatment advancements.

Microbiome-based therapies for periodontitis and peri-implantitis

OBJECTIVES

Periodontitis and peri-implantitis are oral infectious-inflammatory diseases associated with oral microbial dysbiosis. Microbiome-based therapies, characterized by manipulation of the microbiota, are emerging as promising therapeutic approaches to resolve the microbial dysbiosis and associated dysregulation of immune system. This review aims at summarizing recent progress on microbiome-based therapies in periodontitis and peri-implantitis, promoting a further understanding of the related therapeutic mechanisms.

SUBJECTS AND METHODS

Pertinent literatures focused on microbiome-based therapies for periodontitis and peri-implantitis are obtained from PubMed and Web of Science.

RESULTS

In this article, we review the roles and therapeutic mechanisms of four microbiome-based therapies, including probiotics, postbiotics, predatory bacteria and phages, and microbiota transplantation, in the management of periodontitis and peri-implantitis. Challenges facing this field are also discussed, highlighting the areas that require more attention and investigation.

CONCLUSIONS

Microbiome-based therapies may serve as effective treatment for periodontitis and peri-implantitis. This review presents a new viewpoint to this field.

Causal effect between gut microbiota and gastroesophageal reflux disease: a bidirectional two-sample Mendelian randomization study

Previous observational studies have found that the gut microbiota is closely related to the pathogenesis of gastroesophageal reflux disease (GERD), while their causal relationship is unclear. A two-sample multivariate Mendelian randomization analysis was implemented to estimate the causal effect of gut microbiota on GERD. The gut microbiota aggregated statistics were derived from a meta-analysis of the largest available genome-wide association studies (GWAS) conducted by the MiBioGen alliance ( n  = 13 266). GERD aggregated statistics were derived from published GWAS (129 080 cases and 473 524 controls). A bidirectional two-sample Mendelian randomization study was conducted to explore the causal relationship between gut microbiota and GERD using the inverse variance weighted (IVW), Mendelian randomization Egger, single model, weighted median, and weighted model. To verify the stability of the main results of Mendelian randomization analysis, we performed sensitivity analysis. Based on the results of IVW, we found that Anaerostipes was causally associated with an increased risk of GERD [odds ratio (OR): 1.09, P  = 0.018]. Eight gut microbiota taxa ( Actinobacteria, Bifidobacteriales, Bifidobacteriaceae, Clostridiales vadin BB60 group, Rikenellaceae, Lachnospiraceae UCG004, Methanobrevibacter , and unknown genus id.1000000073 ) are predicted to act causally in suppressing the risk of GERD ( P  < 0.05). In addition, reverse Mendelian randomization analyses revealed that the abundance of 15 gut microbiota taxon was found to be affected by GERD. No significant estimation of heterogeneity or pleiotropy is detected. Our study presents a complicated causal relationship between gut microbiota and GERD that offers guidance on the selection of appropriate probiotics as clinical interventions for GERD.

Heart failure-induced microbial dysbiosis contributes to colonic tumour formation in mice

AIMS

Heart failure (HF) and cancer are the leading causes of death worldwide. Epidemiological studies revealed that HF patients are prone to develop cancer. Preclinical studies provided some insights into this connection, but the exact mechanisms remain elusive. In colorectal cancer (CRC), gut microbial dysbiosis is linked to cancer progression and recent studies have shown that HF patients display microbial dysbiosis. This current study focussed on the effects of HF-induced microbial dysbiosis on colonic tumour formation.

METHODS AND RESULTS

C57BL/6J mice were subjected to myocardial infarction (MI), with sham surgery as control. After six weeks faeces were collected, processed for 16 s rRNA sequencing, and pooled for faecal microbiota transplantation. CRC tumour growth was provoked in germ-free mice by treating them with Azoxymethane/Dextran sodium sulphate. The CRC mice were transplanted with faeces from MI or sham mice. MI-induced HF resulted in microbial dysbiosis, characterized by a decreased α-diversity and microbial alterations on the genus level, several of which have been associated with CRC. We then performed faecal microbiota transplantation with faeces from HF mice in CRC mice, which resulted in a higher endoscopic disease score and an increase in the number of tumours in CRC mice.

CONCLUSION

We demonstrated that MI-induced HF contributes to colonic tumour formation by altering the gut microbiota composition, providing a mechanistic explanation for the observed association between HF and increased risk for cancer. Targeting the microbiome may present as a tool to mitigate HF-associated co-morbidities, especially cancer.

Parvimonas micra can translocate from the subgingival sulcus of the human oral cavity to colorectal adenocarcinoma

Oral and intestinal samples from a cohort of 93 colorectal cancer (CRC) patients and 30 healthy controls (non-CRC) were collected for microbiome analysis. Saliva (28 non-CRC and 94 CRC), feces (30 non-CRC and 97 CRC), subgingival fluid (20 CRC), and tumor tissue samples (20 CRC) were used for 16S metabarcoding and/or RNA sequencing (RNAseq) approaches. A differential analysis of the abundance, performed with the ANCOM-BC package, adjusting the P-values by the Holm-Bonferroni method, revealed that Parvimonas was significantly over-represented in feces from CRC patients (P-value < 0.001) compared to healthy controls. A total of 11 Parvimonas micra isolates were obtained from the oral cavity and adenocarcinoma of CRC patients. Genome analysis identified a pair of isolates from the same patient that shared 99.2% identity, demonstrating that P. micra can translocate from the subgingival cavity to the gut. The data suggest that P. micra could migrate in a synergistic consortium with other periodontal bacteria. Metatranscriptomics confirmed that oral bacteria were more active in tumor than in non-neoplastic tissues. We suggest that P. micra could be considered as a CRC biomarker detected in non-invasive samples such as feces.

The multispecies microbial cluster of Fusobacterium, Parvimonas, Bacteroides and Faecalibacterium as a precision biomarker for colorectal cancer diagnosis

The incidence of colorectal cancer (CRC) has increased worldwide, and early diagnosis is crucial to reduce mortality rates. Therefore, new noninvasive biomarkers for CRC are required. Recent studies have revealed an imbalance in the oral and gut microbiomes of patients with CRC, as well as impaired gut vascular barrier function. In the present study, the microbiomes of saliva, crevicular fluid, feces, and non-neoplastic and tumor intestinal tissue samples of 93 CRC patients and 30 healthy individuals without digestive disorders (non-CRC) were analyzed by 16S rRNA metabarcoding procedures. The data revealed that Parvimonas, Fusobacterium, and Bacteroides fragilis were significantly over-represented in stool samples of CRC patients, whereas Faecalibacterium and Blautia were significantly over-abundant in the non-CRC group. Moreover, the tumor samples were enriched in well-known periodontal anaerobes, including Fusobacterium, Parvimonas, Peptostreptococcus, Porphyromonas, and Prevotella. Co-occurrence patterns of these oral microorganisms were observed in the subgingival pocket and in the tumor tissues of CRC patients, where they also correlated with other gut microbes, such as Hungatella. This study provides new evidence that oral pathobionts, normally located in subgingival pockets, can migrate to the colon and probably aggregate with aerobic bacteria, forming synergistic consortia. Furthermore, we suggest that the group composed of Fusobacterium, Parvimonas, Bacteroides, and Faecalibacterium could be used to design an excellent noninvasive fecal test for the early diagnosis of CRC. The combination of these four genera would significantly improve the reliability of a discriminatory test with respect to others that use a single species as a unique CRC biomarker.

BugSigDB captures patterns of differential abundance across a broad range of host-associated microbial signatures

The literature of human and other host-associated microbiome studies is expanding rapidly, but systematic comparisons among published results of host-associated microbiome signatures of differential abundance remain difficult. We present BugSigDB, a community-editable database of manually curated microbial signatures from published differential abundance studies accompanied by information on study geography, health outcomes, host body site and experimental, epidemiological and statistical methods using controlled vocabulary. The initial release of the database contains >2,500 manually curated signatures from >600 published studies on three host species, enabling high-throughput analysis of signature similarity, taxon enrichment, co-occurrence and coexclusion and consensus signatures. These data allow assessment of microbiome differential abundance within and across experimental conditions, environments or body sites. Database-wide analysis reveals experimental conditions with the highest level of consistency in signatures reported by independent studies and identifies commonalities among disease-associated signatures, including frequent introgression of oral pathobionts into the gut.

Comparative Lipidomics of Oral Commensal and Opportunistic Bacteria

The oral cavity contains a vast array of microbes that contribute to the balance between oral health and disease. In addition, oral bacteria can gain access to the circulation and contribute to other diseases and chronic conditions. There are a limited number of publications available regarding the comparative lipidomics of oral bacteria and fungi involved in the construction of oral biofilms, hence our decision to study the lipidomics of representative oral bacteria and a fungus. We performed high-resolution mass spectrometric analyses (<2.0 ppm mass error) of the lipidomes from five Gram-positive commensal bacteria: Streptococcus oralis, Streptococcus intermedius, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus gordonii; five Gram-positive opportunistic bacteria: Streptococcus mutans, Staphylococcus epidermis, Streptococcus acidominimus, Actinomyces viscosus, and Nanosynbacter lyticus; seven Gram-negative opportunistic bacteria: Porphyromonas gingivalis. Prevotella brevis, Proteus vulgaris, Fusobacterium nucleatum, Veillonella parvula, Treponema denticola, and Alkermansia muciniphila; and one fungus: Candida albicans. Our mass spectrometric analytical platform allowed for a detailed evaluation of the many structural modifications made by microbes for the three major lipid scaffolds: glycerol, sphingosine and fatty acyls of hydroxy fatty acids (FAHFAs).

Impact of Periodontitis on the Leakage of Oral Bacteria to the Gut

Colorectal cancer (CRC) and periodontitis have recently been related due to the higher incidence of CRC in periodontal patients and the involvement of periodontal pathogens in carcinogenesis, suggesting that leakage from the oral cavity to the gut occurs. However, the magnitude of this pass-through in healthy individuals is controversial, and the effect that periodontitis could play in it is understudied. To evaluate the rate of bacterial leakage from the oral cavity to the gut, we analyzed the microbial composition of saliva, subgingival plaque, and fecal samples in healthy individuals without gastrointestinal disorders, including 20 periodontitis patients and 20 oral healthy controls, using PacBio full-length 16S rRNA gene sequencing. As expected, we observed a higher abundance of periodontal pathogens in the subgingival plaque and saliva of periodontal patients. In contrast, no significant differences were found between the fecal samples of both groups, implying that gut samples from periodontal patients were not enriched in periodontal pathogens. Fusobacterium nucleatum, a biomarker of CRC, was not found in the fecal samples of any participant. Our study does show a small leakage of some oral bacteria (mainly streptococci) to the gut, regardless of periodontal health status. Future studies should test whether other host factors and/or the preexistence of a gut disorder must be present in addition to periodontitis to promote the colonization of the gut by oral pathogens. The absence of periodontal pathogens in feces supports the idea that these bacteria could be used as biomarkers of intestinal disorders, including CRC.

Explainable artificial intelligence for microbiome data analysis in colorectal cancer biomarker identification

Background

Colorectal cancer (CRC) is a type of tumor caused by the uncontrolled growth of cells in the mucosa lining the last part of the intestine. Emerging evidence underscores an association between CRC and gut microbiome dysbiosis. The high mortality rate of this cancer has made it necessary to develop new early diagnostic methods. Machine learning (ML) techniques can represent a solution to evaluate the interaction between intestinal microbiota and host physiology. Through explained artificial intelligence (XAI) it is possible to evaluate the individual contributions of microbial taxonomic markers for each subject. Our work also implements the Shapley Method Additive Explanations (SHAP) algorithm to identify for each subject which parameters are important in the context of CRC.

Results

The proposed study aimed to implement an explainable artificial intelligence framework using both gut microbiota data and demographic information from subjects to classify a cohort of control subjects from those with CRC. Our analysis revealed an association between gut microbiota and this disease. We compared three machine learning algorithms, and the Random Forest (RF) algorithm emerged as the best classifier, with a precision of 0.729 ± 0.038 and an area under the Precision-Recall curve of 0.668 ± 0.016. Additionally, SHAP analysis highlighted the most crucial variables in the model's decision-making, facilitating the identification of specific bacteria linked to CRC. Our results confirmed the role of certain bacteria, such as Fusobacterium, Peptostreptococcus, and Parvimonas, whose abundance appears notably associated with the disease, as well as bacteria whose presence is linked to a non-diseased state.

Discussion

These findings emphasizes the potential of leveraging gut microbiota data within an explainable AI framework for CRC classification. The significant association observed aligns with existing knowledge. The precision exhibited by the RF algorithm reinforces its suitability for such classification tasks. The SHAP analysis not only enhanced interpretability but identified specific bacteria crucial in CRC determination. This approach opens avenues for targeted interventions based on microbial signatures. Further exploration is warranted to deepen our understanding of the intricate interplay between microbiota and health, providing insights for refined diagnostic and therapeutic strategies.

Classical and Innovative Evidence for Therapeutic Strategies in Retinal Dysfunctions

The human retina is a complex anatomical structure that has no regenerative capacity. The pathogenesis of most retinopathies can be attributed to inflammation, with the activation of the inflammasome protein platform, and to the impact of oxidative stress on the regulation of apoptosis and autophagy/mitophagy in retinal cells. In recent years, new therapeutic approaches to treat retinopathies have been investigated. Experimental data suggest that the secretome of mesenchymal cells could reduce oxidative stress, autophagy, and the apoptosis of retinal cells, and in turn, the secretome of the latter could induce changes in mesenchymal cells. Other studies have evidenced that noncoding (nc)RNAs might be new targets for retinopathy treatment and novel disease biomarkers since a correlation has been found between ncRNA levels and retinopathies. A new field to explore is the interaction observed between the ocular and intestinal microbiota; indeed, recent findings have shown that the alteration of gut microbiota seems to be linked to ocular diseases, suggesting a gut-eye axis. To explore new therapeutical strategies for retinopathies, it is important to use proper models that can mimic the complexity of the retina. In this context, retinal organoids represent a good model for the study of the pathophysiology of the retina.

The impact of a modified microbiota-accessible carbohydrate diet on gut microbiome and clinical symptoms in colorectal cancer patients following surgical resection

A high-fiber diet is widely recognized for its positive effects on the gut microbiome. However, the specific impact of a high-fiber diet on the gut microbiome and bowel habits of patients with colon cancer remains poorly understood. In this study, we aimed to assess the effects of a modified microbiota-accessible carbohydrate (mMAC) diet on gut microbiota composition and clinical symptoms in colon cancer patients who underwent surgical resection. To achieve this, we enrolled 40 patients in two groups: those who received adjuvant chemotherapy and those who did not. Fecal samples were collected before and after dietary interventions for microbial and metabolite analyses. Each group was randomized in a 1: 1 ratio to follow either a 3-week conventional diet followed by a 3-week mMAC diet, or the reverse sequence. Although there were no significant differences in the microbial diversity data before and after the mMAC diet in both the non-chemotherapy and chemotherapy groups, distinct differences in gut microbial composition were revealed after the mMAC diet. Specifically, the abundance of Prevotella, which is associated with high-fiber diets, was further elevated with increased concentrations of acetate and propionate after the mMAC diet. Additionally, patients who experienced improved diarrhea and constipation after the mMAC diet exhibited an enrichment of beneficial bacteria and notable changes in metabolites. In conclusion, this study provides valuable insights into the potential benefits of the mMAC diet, specifically its impact on the gut microbiome and clinical symptoms in postoperative colorectal cancer (CRC) patients. These findings emphasize the potential role of a high-fiber diet in influencing the gut microbiome, and the clinical symptoms warrant further investigation.

Dental visits and colon-rectum cancer: A nationwide population-based nested case-control study in Taiwan

Background/purpose

Although oral health and systemic diseases are closely associated, little is known about the utilization of ambulatory dental visits in patients prior to diagnosis of colon-rectum cancer (CRC). In this study, a nested case-control study based on the population-based health claim database was conducted to clarify the relationship between dental visits and CRC in Taiwan.

Materials and methods

From the Longitudinal Health Insurance Research Database 2010 (LHIRD 2010), we identified 4787 patients who were newly diagnosed with CRC from 2005 to 2013. We also recruited 19,148 control subjects matched in a 1:4 ratio based on sex and age at the index date from LHIRD 2010. Both groups were retrospectively traced back to 1997 to obtain any records of ambulatory dental visits that occurred within 8 years prior to the index date. ICD-9 codes 520-529 for diseases of oral cavity, salivary glands, and jaw were defined as dental visits.

Results

The mean frequency of dental visits within 8 years prior to index date among patients with CRC were significantly higher than the control group (P = 0.005). Patients with CRC had significantly higher proportions of certain co-morbidities than control group. However, periodontal treatment, caries filling, and tooth extraction were borderline and not significantly related to CRC after adjustment.

Conclusion

Our results indicate that the utilization of ambulatory dental visits is significantly increased in patients with CRC prior to its diagnosis. Certain co-morbidities may also affect the frequency of dental visits and the occurrence of CRC.

The Effect of Bacterial Composition Shifts in the Oral Microbiota on Alzheimer's Disease

Alzheimer's disease (AD), a neurological disorder, despite significant advances in medical science, has not yet been definitively cured, and the exact causes of the disease remain unclear. Due to the importance of AD in the clinic, large expenses are spent annually to deal with this neurological disorder, and neurologists warn of an increase in this disease in elderly in the near future. It has been believed that microbiota dysbiosis leads to Alzheimer's as a multi-step disease. In this regard, the presence of footprints of perturbations in the oral microbiome and the predominance of pathogenic bacteria and their effect on the nervous system, especially AD, is a very interesting topic that has been considered by researchers in the last decade. Some studies have looked at the mechanisms by which oral microbiota cause AD. However, many aspects of this interaction are still unclear as to how oral microbiota composition can contribute to this disease. Understanding this interaction requires extensive collaboration by interdisciplinary researchers to explore all aspects of the issue. In order to reveal the link between the composition of the oral microbiota and this disease, researchers from various domains have sought to explain the mechanisms of shift in oral microbiota in AD in this review.

Salivary microbiome profiles for different clinical phenotypes of pituitary adenomas by single-molecular long-read sequencing

IMPORTANCE

The gut and salivary microbiomes have been widely reported to be significantly associated with a number of neurological disorders. The stability of the microbiome in the oral cavity makes it a potentially ideal sample that can be conveniently obtained for the investigation of microbiome-based pathogenesis in diseases. In the present study, we used a single-molecule long-read sequencing technique to study the distribution of the salivary microbiota in patients with pituitary adenoma (PA) and healthy individuals, as well as among four clinical phenotypes of PA. We found that the diversity of salivary microbes was more abundant in PA patients than in healthy individuals. We also observed some unique genera in different PA phenotypes. The bioinformatics-based functional predictions identified potential links between microbes and different clinical phenotypes of PA. This study improves the existing understanding of the pathogenesis of PA and may provide diagnostic and therapeutic targets for PA.

Parvimonas micra, an oral pathobiont associated with colorectal cancer, epigenetically reprograms human colonocytes

Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and investigate one of these oral pathobionts, the Gram-positive anaerobic coccus Parvimonas micra. We identified two phylotypes (A and B) exhibiting different phenotypes and adhesion capabilities. We observed a strong association of phylotype A with CRC, with its higher abundance in feces and in tumoral tissue compared with the normal homologous colonic mucosa, which was associated with a distinct methylation status of patients. By developing an in vitro hypoxic co-culture system of human primary colonic cells with anaerobic bacteria, we show that P. micra phylotype A alters the DNA methylation profile promoters of key tumor-suppressor genes, oncogenes, and genes involved in epithelial-mesenchymal transition. In colonic mucosa of CRC patients carrying P. micra phylotype A, we found similar DNA methylation alterations, together with significant enrichment of differentially expressed genes in pathways involved in inflammation, cell adhesion, and regulation of actin cytoskeleton, providing evidence of P. micra's possible role in the carcinogenic process.

Mechanism and application of Lactobacillus in type 2 diabetes-associated periodontitis

Type 2 diabetes mellitus (T2DM) accelerates the progression of periodontitis through diverse pathways. Abnormal immune responses, excessive activation of inflammation, increased levels of advanced glycation end products, and oxidative stress have defined roles in the pathophysiological process of T2DM-associated periodontitis. Furthermore, in the periodontium of diabetic individuals, there are high levels of advanced glycation end-products and glucose. Meanwhile, progress in microbiomics has revealed that dysbacteriosis caused by T2DM also contributes to the progression of periodontitis. Lactobacillus, owing to its fine-tuning function in the local microbiota, has sparked tremendous interest in this field. Accumulating research on Lactobacillus has detailed its beneficial role in both diabetes and oral diseases. In this study, we summarize the newly discovered mechanisms underlying Lactobacillus-mediated improvement of T2DM-associated periodontitis and propose the application of Lactobacillus in the clinic.

Host Transcriptional Regulatory Genes and Microbiome Networks Crosstalk through Immune Receptors Establishing Normal and Tumor Multiomics Metafirm of the Oral-Gut-Lung Axis

The microbiome has shown a correlation with the diet and lifestyle of each population in health and disease, the ability to communicate at the cellular level with the host through innate and adaptative immune receptors, and therefore an important role in modulating inflammatory process related to the establishment and progression of cancer. The oral cavity is one of the most important interaction windows between the human body and the environment, allowing the entry of an important number of microorganisms and their passage across the gastrointestinal tract and lungs. In this review, the contribution of the microbiome network to the establishment of systemic diseases like cancer is analyzed through their synergistic interactions and bidirectional crosstalk in the oral-gut-lung axis as well as its communication with the host cells. Moreover, the impact of the characteristic microbiota of each population in the formation of the multiomics molecular metafirm of the oral-gut-lung axis is also analyzed through state-of-the-art sequencing techniques, which allow a global study of the molecular processes involved of the flow of the microbiota environmental signals through cancer-related cells and its relationship with the establishment of the transcription factor network responsible for the control of regulatory processes involved with tumorigenesis.

The oral-gut-circulatory axis: from homeostasis to colon cancer

The human microbiota is widely recognized as providing crucial health benefits to its host, specifically by modulating immune homeostasis. Microbial imbalance, known as dysbiosis, is linked to several conditions in the body. The oral cavity and gut host the two largest microbial communities playing a major role in microbial-associated diseases. While the oral-gut axis has been previously explored, our review uniquely highlights the significance of incorporating the circulatory system into this axis. The interaction between immune cells, inflammatory factors, circulating bacteria, and microbial metabolites influences the homeostasis of both the oral and gut microbiota in a bidirectional manner. In this comprehensive review, we aim to describe the bacterial components of the oral-gut-circulatory axis in both health and disease, with a specific focus on colon cancer.

The effect of Abrus cantoniensis Hance on liver damage in mice

The liver is a well-known organ contributing to digestion, hemostasis and detoxification, while liver injury is a world-widely distributed health problem with limited treatment choices. We detected the protective effect of Abrus cantoniensis Hance (ACH) on Carbon tetrachloride-induced (CCl4) liver injury in mice. Fifty ICR (Institute of Cancer Research) animals were grouped into five groups of control (a), CCl4 (d), ACH (25 mg/kg) treated group (c), ACH (50 mg/kg) treated group (b), and ACH (100 mg/kg) treated group (e). Mice in groups d, c, b, and e were given CCl4 every four days, and treated animals received daily ACH supplementation. The results showed that the daily body weights in CCl4-induced animals were slightly lower; however, the weight of ACH-treated mice increased, particularly in the higher dose group. Treatment with CCl4 led to increased liver weight and liver indices in mice, whereas supplementation with ACH reduced both liver weights and liver indices in animals. Histo-pathological analysis indicated that CCl4 led to inflammatory cell infiltration and hepatocellular degeneration, with collagenous fibers proliferation in ICR animals. In contrast, supplementation with ACH prominently decreased inflammatory cells and degeneration of hepatocytes and inhibited collagen fiber hyperplasia. Furthermore, the levels or concentrations of AST (p < 0.0001), ALT (p < 0.0001), MDA (p < 0.0001), IL-1β (p < 0.01), TNF-α (p < 0.01) and IL-6 (p < 0.01) were significantly higher in CCl4 induced ICR animals in group d. However, mice treated with ACH showed lower levels or concentrations of those indices in dose dependent manner. The levels of GSH-px (p < 0.0001), CAT (p < 0.0001) and SOD (p < 0.0001) were significantly reduced in CCl4 group; however, all these three enzymes exhibited significant (p < 0.05) increase in animals supplemented with ACH in dose dependent manner. The microbiome sequencing generated 1,168,327 filtered reads in the mice samples. A notable difference was observed in the composition of 6 phyla and 37 genera among the five ICR animal groups. Supplementation with ACH increased the abundance of beneficial genera of Coprococcus, Blautia and Clostridium, while concurrently decreased the presence of pathogenic genera of Mycoplasma and Helicobacter. In conclusion, we revealed that Abrus cantoniensis Hance has the potential to relieve liver damage induced by CCl4, through the reduction of inflammation, enhancement of antioxidant capacity, and regulation of intestinal microbiota.

The role of oral microbiota in cancer

Cancer remains a significant global challenge, with an estimated 47% increase in cancer patients from 2020 to 2040. Increasing research has identified microorganism as a risk factor for cancer development. The oral cavity, second only to the colon, harbors more than 700 bacterial species and serves as a crucial microbial habitat. Although numerous epidemiological studies have reported associations between oral microorganisms and major systemic tumors, the relationship between oral microorganisms and cancers remains largely unclear. Current research primarily focuses on respiratory and digestive system tumors due to their anatomical proximity to the oral cavity. The relevant mechanism research mainly involves 47% dominant oral microbial population that can be cultured in vitro. However, further exploration is necessary to elucidate the mechanisms underlying the association between oral microbiota and tumors. This review systematically summarizes the reported correlations between oral microbiota and common cancers while also outlining potential mechanisms that may guide biological tumor treatment.

Evaluation of an Adapted Semi-Automated DNA Extraction for Human Salivary Shotgun Metagenomics

Recent attention has highlighted the importance of oral microbiota in human health and disease, e.g., in Parkinson's disease, notably using shotgun metagenomics. One key aspect for efficient shotgun metagenomic analysis relies on optimal microbial sampling and DNA extraction, generally implementing commercial solutions developed to improve sample collection and preservation, and provide high DNA quality and quantity for downstream analysis. As metagenomic studies are today performed on a large number of samples, the next evolution to increase study throughput is with DNA extraction automation. In this study, we proposed a semi-automated DNA extraction protocol for human salivary samples collected with a commercial kit, and compared the outcomes with the DNA extraction recommended by the manufacturer. While similar DNA yields were observed between the protocols, our semi-automated DNA protocol generated significantly higher DNA fragment sizes. Moreover, we showed that the oral microbiome composition was equivalent between DNA extraction methods, even at the species level. This study demonstrates that our semi-automated protocol is suitable for shotgun metagenomic analysis, while allowing for improved sample treatment logistics with reduced technical variability and without compromising the structure of the oral microbiome.

Maternal Diet Determines Milk Microbiome Composition and Offspring Gut Colonization in Wistar Rats

Mother's milk contains a unique microbiome that plays a relevant role in offspring health. We hypothesize that maternal malnutrition during lactation might impact the microbial composition of milk and affect adequate offspring gut colonization, increasing the risk for later onset diseases. Then, Wistar rats were fed ad libitum (Control, C) food restriction (Undernourished, U) during gestation and lactation. After birth, offspring feces and milk stomach content were collected at lactating day (L)4, L14 and L18. The V3-V4 region of the bacterial 16S rRNA gene was sequenced to characterize bacterial communities. An analysis of beta diversity revealed significant disparities in microbial composition between groups of diet at L4 and L18 in both milk, and fecal samples. In total, 24 phyla were identified in milk and 18 were identified in feces, with Firmicutes, Proteobacteria, Actinobacteroidota and Bacteroidota collectively representing 96.1% and 97.4% of those identified, respectively. A higher abundance of Pasteurellaceae and Porphyromonas at L4, and of Gemella and Enterococcus at L18 were registered in milk samples from the U group. Lactobacillus was also significantly more abundant in fecal samples of the U group at L4. These microbial changes compromised the number and variety of milk-feces or feces-feces bacterial correlations. Moreover, increased offspring gut permeability and an altered expression of goblet cell markers TFF3 and KLF3 were observed in U pups. Our results suggest that altered microbial communication between mother and offspring through breastfeeding may explain, in part, the detrimental consequences of maternal malnutrition on offspring programming.

Case Report: Resolution of high grade anal squamous intraepithelial lesion with antibiotics proposes a new role for syphilitic infection in potentiation of HPV-associated ASCC

Introduction

Human Papillomavirus (HPV) is the primary risk factor for the development of anal intraepithelial neoplasia (AIN) and is a leading risk factor for anogenital squamous cell carcinoma (ASCC). Despite common shared risk factors for both HPV and syphilis, co-infection is not well documented, and the role of syphilitic infection in HPV-associated AIN and ASCC potentiation is not defined.

Case description/methods

A 72-year-old single male presented with complaints of mild rectal pain and intermittent rectal bleeding. A flexible sigmoidoscopy was performed, and a firm 4.5cm x 3cm perianal mass was detected and superficially biopsied. Pathology findings demonstrated evidence of a high grade squamous intraepithelial lesion (HGSIL, AIN II/III/AIS) with viral cytopathic effect, consistent with HPV infection. Much of the biopsied lesion showed acanthotic squamous mucosa with intraepithelial neutrophils and abundant submucosal plasma cells, suggesting possible syphilitic involvement. Subsequent immunohistochemical staining for p16 as a surrogate marker for HPV was positive, as was an immunohistochemical stain for spirochetes, supportive of co-infection with Treponema pallidum pallidum (T. pallidum), the causative agent in venereal syphilis. The patient was referred to an infectious disease specialist for syphilitic infection and was treated with penicillin with surprisingly complete resolution of the lesion. EUAs were performed 2- and 3-months following treatment without lesion recurrence. However, one year following diagnosis, a flexible sigmoidoscopy revealed a 5 mm recurrent HPV-related low-grade AIN 1 lesion at the dentate line.

Discussion

Resolution of the lesion by antibiotic treatment for syphilitic infection suggested that co-infection by T. pallidum may potentiate HPV-associated squamous cell carcinoma based on histological findings. Findings from this case, as well as a review of bacterial involvement and potentiation in various cancers, are reviewed here. Such findings offer new insight regarding the role of STI-associated bacteria and HPV co-infection in the establishment of AIN and may additionally propose new treatment modalities for ASCC.

Oral Microbiota: A New Insight into Cancer Progression, Diagnosis and Treatment

The polymorphic microbiome has been defined as one of the "Hallmarks of Cancer". Extensive studies have now uncovered the role of oral microbiota in cancer development and progression. Bacteria, fungi, archaea, and viruses in the oral cavity interact dynamically with the oral microenvironment to maintain the oral micro-ecological homeostasis. This complex interaction is influenced by many factors, such as maternal transmission, personal factors and environmental factors. Dysbiosis of oral microbiota can disturbed this host-microbiota interaction, leading to systemic diseases. Numerous studies have shown the potential associations between oral microbiota and a variety of cancers. However, the underlying mechanisms and therapeutic insights are still poorly understood. In this review, we mainly focus on the following aspects: (1) the factors affect oral microbiota composition and function; (2) the interaction between microenvironment and oral microbiota; (3) the role of multi-kingdom oral microbiota in human health; (4) the potential underlying mechanisms and therapeutic benefits of oral microbiota against cancer. Finally, we aim to describe the impact of oral microbiota on cancer progression and provide novel therapeutic insights into cancer prevention and treatment by targeting oral microbiota.