Acetyltransferase from Akkermansia muciniphila blunts colorectal tumourigenesis by reprogramming tumour microenvironment

The interactions between traditional Chinese medicine and gut microbiota in cancers: Current status and future perspectives

The gut microbiota, known as the "forgotten organ" and "human second genome," comprises a complex microecosystem. It significantly influences the development of various tumors, including colorectal, liver, stomach, breast, and lung cancers, through both direct and indirect mechanisms. These mechanisms include the "gut-liver" axis, the "lung-intestine" axis, and interactions with the immune system. The intestinal flora exhibits dual roles in cancer, both promoting and suppressing its progression. Traditional Chinese medicine (TCM) can alter cancer progression by regulating the intestinal flora. It modifies the intestinal flora's composition and structure, along with the levels of endogenous metabolites, thus affecting the intestinal barrier, immune system, and overall body metabolism. These actions contribute to TCM's significant antitumor effects. Moreover, the gut microbiota metabolizes TCM components, enhancing their antitumor properties. Therefore, exploring the interaction between TCM and the intestinal flora offers a novel perspective in understanding TCM's antitumor mechanisms. This paper succinctly reviews the association between gut flora and the development of tumors, including colorectal, liver, gastric, breast, and lung cancers. It further examines current research on the interaction between TCM and intestinal flora, with a focus on its antitumor efficacy. It identifies limitations in existing studies and suggests recommendations, providing insights into antitumor drug research and exploring TCM's antitumor effectiveness. Additionally, this paper aims to guide future research on TCM and the gut microbiota in antitumor studies.

Akkermania muciniphila: a rising star in tumor immunology

Tumor is accompanied by complex and dynamic microenvironment development, and the interaction of all its components influences disease progression and response to treatment. Once the tumor microenvironment has been eradicated, various mechanisms can induce the tumors. Microorganisms can maintain the homeostasis of the tumor microenvironment through immune regulation, thereby inhibiting tumor development. Akkermania muciniphila (A. muciniphila), an anaerobic bacterium, can induce tumor immunity, regulate the gastrointestinal microenvironment through metabolites, outer membrane proteins, and some cytokines, and enhance the curative effect through combined immunization. Therefore, a comprehensive understanding of the complex interaction between A. muciniphila and human immunity will facilitate the development of immunotherapeutic strategies in the future and enable patients to obtain a more stable clinical response. This article reviews the most recent developments in the tumor immunity of A. muciniphila.

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

There are a growing number of studies linking the composition of the human microbiome to disease states and treatment responses, especially in the context of cancer. This has raised significant interest in developing microbes and microbial products as cancer immunotherapeutics that mimic or recapitulate the beneficial effects of host-microbe interactions. Bacterial extracellular vesicles (bEVs) are nano-sized, membrane-bound particles secreted by essentially all bacteria species and contain a diverse bioactive cargo of the producing cell. They have a fundamental role in facilitating interactions among cells of the same species, different microbial species, and even with multicellular host organisms in the context of colonization (microbiome) and infection. The interaction of bEVs with the immune system has been studied extensively in the context of infection and suggests that bEV effects depend largely on the producing species. They thus provide functional diversity, while also being nonreplicative, having inherent cell-targeting qualities, and potentially overcoming natural barriers. These characteristics make them highly appealing for development as cancer immunotherapeutics. Both natively secreted and engineered bEVs are now being investigated for their application as immunotherapeutics, vaccines, drug delivery vehicles, and combinations of the above, with promising early results. This suggests that both the intrinsic immunomodulatory properties of bEVs and their ability to be modified could be harnessed for the development of next-generation microbe-inspired therapies. Nonetheless, there remain major outstanding questions regarding how the observed preclinical effectiveness will translate from murine models to primates, and humans in particular. Moreover, research into the pharmacology, toxicology, and mass manufacturing of this potential novel therapeutic platform is still at early stages. In this review, we highlight the breadth of bEV interactions with host cells, focusing on immunologic effects as the main mechanism of action of bEVs currently in preclinical development. We review the literature on ongoing efforts to develop natively secreted and engineered bEVs from a variety of bacterial species for cancer therapy and finally discuss efforts to overcome outstanding challenges that remain for clinical translation.

Microbiome bacterial influencers of host immunity and response to immunotherapy

The gut microbiota influences anti-tumor immunity and can induce or inhibit response to immune checkpoint inhibitors (ICIs). Therefore, microbiome features are being studied as predictive/prognostic biomarkers of patient response to ICIs, and microbiome-based interventions are attractive adjuvant treatments in combination with ICIs. Specific gut-resident bacteria can influence the effectiveness of immunotherapy; however, the mechanism of action on how these bacteria affect anti-tumor immunity and response to ICIs is not fully understood. Nevertheless, early bacterial-based therapeutic strategies have demonstrated that targeting the gut microbiome through various methods can enhance the effectiveness of ICIs, resulting in improved clinical responses in patients with a diverse range of cancers. Therefore, understanding the microbiota-driven mechanisms of response to immunotherapy can augment the success of these interventions, particularly in patients with treatment-refractory cancers.

The role of Akkermansia muciniphila in colorectal cancer: A double-edged sword of treatment or disease progression?

Colorectal cancer (CRC) is the second most cancer-related death worldwide. In recent years, probiotics have been used to reduce the potential risks of CRC and tumors with various mechanisms. Different bacteria have been suggested to play different roles in the progression, prevention, or treatment of CRC. Akkermansia muciniphila is considered a next-generation probiotic for preventing and treating some diseases. Therefore, in this review article, we aimed to describe and discuss different mechanisms of A. muciniphila as an intestinal microbiota or probiotic in CRC. Some studies suggested that the abundance of A. muciniphila was higher or increased in CRC patients compared to healthy individuals. However, the decreased abundance of A. muciniphila was associated with severe symptoms of CRC, indicating that A. muciniphila did not play a role in the development of CRC. In addition, A. muciniphila administration elevates gene expression of proliferation-associated molecules such as S100A9, Dbf4, and Snrpd1, or markers for cell proliferation. Some other studies suggested that inflammation and tumorigenesis in the intestine might promoted by A. muciniphila. Overall, the role of A. muciniphila in CRC development or inhibition is still unclear and controversial. Various methods of bacterial supplementation, such as viability, bacterial number, and abundance, could all influence the colonization effect of A. muciniphila administration and CRC progression. Overall, A. mucinipila has been revealed to modulate the therapeutic potential of immune checkpoint inhibitors. Preliminary human data propose that oral consumption of A. muciniphila is safe, but its efficacy needs to be confirmed in more human clinical studies.

Distinct intratumoral microbiome of young-onset and average-onset colorectal cancer

BACKGROUND

The unexplained rise of young-onset CRC (yoCRC, age <50 years) is of concern. Evidence suggests that microbial dysbiosis may be a contributing factor, but the tumor microbial profile of yoCRC in comparison to average-onset CRC (aoCRC, age >60) has not been fully investigated.

METHODS

16S rRNA amplicon sequencing was performed in tumor and paired adjacent non-malignant fresh frozen tissue specimens prospectively collected from 136 yoCRC and 140 aoCRC patients. Phyloseq, microbiomeSeq, metagenomeSeq, and NetComi were utilized for bioinformatics analysis. Statistical tests included Fisher's exact test, ANOVA, PERMANOVA with Bonferroni correction, linear regression, and Wilcoxon test. p-value <0.05 was considered statistically significant.

FINDINGS

yoCRC patients were more likely to have left-sided (72.8 vs. 54.3%), rectal (36.7% vs. 25%), and stage IV (28% vs. 15%) tumors. yoCRC tumors had significantly higher microbial alpha diversity (p = 1.5 × 10-5) and varied beta diversity (R2 = 0.31, p = 0.013) than aoCRC tumors. yoCRC tumors were enriched with Akkermansia and Bacteroides, whereas aoCRC tumors showed greater relative abundances of Bacillus, Staphylococcus, Listeria, Enterococcus, Pseudomonas, Fusobacterium, and Escherichia/Shigella. Akkermansia had a predominantly negative correlation with the microbial communities in yoCRC tumors. yoCRC and aoCRC tumors had distinct microbial profiles associated with tumor location, sidedness, stage, and obesity. Fusobacterium (R2 = -0.23, p = 0.001) and Akkermansia (R2 = 0.05, p = 0.001) abundance correlated with overall survival in yoCRC.

INTERPRETATION

Our study provides a comprehensive understanding of the microbial perturbations in yoCRC tumors. We identify microbial candidates that may highlight a distinct pathogenesis of yoCRC and serve as preventive, diagnostic, and therapeutic targets.

FUNDING

Sondra and Stephen Hardis Chair in Oncology Research (A.A.K.).

Ginsenoside Rk3 modulates gut microbiota and regulates immune response of group 3 innate lymphoid cells to against colorectal tumorigenesis

The gut microbiota plays a pivotal role in the immunomodulatory and protumorigenic microenvironment of colorectal cancer (CRC). However, the effect of ginsenoside Rk3 (Rk3) on CRC and gut microbiota remains unclear. Therefore, the purpose of this study is to explore the potential effect of Rk3 on CRC from the perspective of gut microbiota and immune regulation. Our results reveal that treatment with Rk3 significantly suppresses the formation of colon tumors, repairs intestinal barrier damage, and regulates the gut microbiota imbalance caused by CRC, including enrichment of probiotics such as Akkermansia muciniphila and Barnesiella intestinihominis, and clearance of pathogenic Desulfovibrio. Subsequent metabolomics data demonstrate that Rk3 can modulate the metabolism of amino acids and bile acids, particularly by upregulating glutamine, which has the potential to regulate the immune response. Furthermore, we elucidate the regulatory effects of Rk3 on chemokines and inflammatory factors associated with group 3 innate lymphoid cells (ILC3s) and T helper 17 (Th17) signaling pathways, which inhibits the hyperactivation of the Janus kinase-signal transducer and activator of transcription 3 (JAK-STAT3) signaling pathway. These results indicate that Rk3 modulates gut microbiota, regulates ILC3s immune response, and inhibits the JAK-STAT3 signaling pathway to suppress the development of colon tumors. More importantly, the results of fecal microbiota transplantation suggest that the inhibitory effect of Rk3 on colon tumors and its regulation of ILC3 immune responses are mediated by the gut microbiota. In summary, these findings emphasize that Rk3 can be utilized as a regulator of the gut microbiota for the prevention and treatment of CRC.

New sights of immunometabolism and agent progress in colitis associated colorectal cancer

Colitis associated colorectal cancer is a disease with a high incidence and complex course that develops from chronic inflammation and deteriorates after various immune responses and inflammation-induced attacks. Colitis associated colorectal cancer has the characteristics of both immune diseases and cancer, and the similarity of treatment models contributes to the similar treatment dilemma. Immunometabolism contributes to the basis of life and is the core of many immune diseases. Manipulating metabolic signal transduction can be an effective way to control the immune process, which is expected to become a new target for colitis associated colorectal cancer therapy. Immune cells participate in the whole process of colitis associated colorectal cancer development by transforming their functional condition via changing their metabolic ways, such as glucose, lipid, and amino acid metabolism. The same immune and metabolic processes may play different roles in inflammation, dysplasia, and carcinoma, so anti-inflammation agents, immunomodulators, and agents targeting special metabolism should be used in combination to prevent and inhibit the development of colitis associated colorectal cancer.

Novel tripeptide RKH derived from Akkermansia muciniphila protects against lethal sepsis

OBJECTIVE

The pathogenesis of sepsis is complex, and the sepsis-induced systemic proinflammatory phase is one of the key drivers of organ failure and consequent mortality. Akkermansia muciniphila (AKK) is recognised as a functional probiotic strain that exerts beneficial effects on the progression of many diseases; however, whether AKK participates in sepsis pathogenesis is still unclear. Here, we evaluated the potential contribution of AKK to lethal sepsis development.

DESIGN

Relative abundance of gut microbial AKK in septic patients was evaluated. Cecal ligation and puncture (CLP) surgery and lipopolysaccharide (LPS) injection were employed to establish sepsis in mice. Non-targeted and targeted metabolomics analysis were used for metabolites analysis.

RESULTS

We first found that the relative abundance of gut microbial AKK in septic patients was significantly reduced compared with that in non-septic controls. Live AKK supplementation, as well as supplementation with its culture supernatant, remarkably reduced sepsis-induced mortality in sepsis models. Metabolomics analysis and germ-free mouse validation experiments revealed that live AKK was able to generate a novel tripeptide Arg-Lys-His (RKH). RKH exerted protective effects against sepsis-induced death and organ damage. Furthermore, RKH markedly reduced sepsis-induced inflammatory cell activation and proinflammatory factor overproduction. A mechanistic study revealed that RKH could directly bind to Toll-like receptor 4 (TLR4) and block TLR4 signal transduction in immune cells. Finally, we validated the preventive effects of RKH against sepsis-induced systemic inflammation and organ damage in a piglet model.

CONCLUSION

We revealed that a novel tripeptide, RKH, derived from live AKK, may act as a novel endogenous antagonist for TLR4. RKH may serve as a novel potential therapeutic approach to combat lethal sepsis after successfully translating its efficacy into clinical practice.

Akkermansia muciniphila - friend or foe in colorectal cancer?

Akkermansia muciniphila is a gram-negative anaerobic bacterium, which represents a part of the commensal human microbiota. Decline in the abundance of A. muciniphila among other microbial species in the gut correlates with severe systemic diseases such as diabetes, obesity, intestinal inflammation and colorectal cancer. Due to its mucin-reducing and immunomodulatory properties, the use of probiotics containing Akkermansia sp. appears as a promising approach to the treatment of metabolic and inflammatory diseases. In particular, a number of studies have focused on the role of A. muciniphila in colorectal cancer. Of note, the results of these studies in mice are contradictory: some reported a protective role of A. muciniphila in colorectal cancer, while others demonstrated that administration of A. muciniphila could aggravate the course of the disease resulting in increased tumor burden. More recent studies suggested the immunomodulatory effect of certain unique surface antigens of A. muciniphila on the intestinal immune system. In this Perspective, we attempt to explain how A. muciniphila contributes to protection against colorectal cancer in some models, while being pathogenic in others. We argue that differences in the experimental protocols of administration of A. muciniphila, as well as viability of bacteria, may significantly affect the results. In addition, we hypothesize that antigens presented by pasteurized bacteria or live A. muciniphila may exert distinct effects on the barrier functions of the gut. Finally, A. muciniphila may reduce the mucin barrier and exerts combined effects with other bacterial species in either promoting or inhibiting cancer development.

Advances in anti-tumor based on various anaerobic bacteria and their derivatives as drug vehicles

Cancer therapies, such as chemotherapy and radiotherapy, are often unsatisfactory due to several limitations, including drug resistance, inability to cross biological barriers, and toxic side effects on the body. These drawbacks underscore the need for alternative treatments that can overcome these challenges and provide more effective and safer options for cancer patients. In recent years, the use of live bacteria, engineered bacteria, or bacterial derivatives to deliver antitumor drugs to specific tumor sites for controlled release has emerged as a promising therapeutic tool. This approach offers several advantages over traditional cancer therapies, including targeted drug delivery and reduced toxicity to healthy tissues. Ongoing research in this field holds great potential for further developing more efficient and personalized cancer therapies, such as E. coli, Salmonella, Listeria, and bacterial derivatives like outer membrane vesicles (OMVs), which can serve as vehicles for drugs, therapeutic proteins, or antigens. In this review, we describe the advances, challenges, and future directions of research on using live bacteria or OMVs as carriers or components derived from bacteria of delivery systems for cancer therapy.

Live and pasteurized Akkermansia muciniphila decrease susceptibility to Salmonella Typhimurium infection in mice

INTRODUCTION

The gut microbiome is vital for providing resistance against colonized pathogenicbacteria. Recently, specific commensal species have become recognized as important mediators of host defense against microbial infection by a variety of mechanisms.

OBJECTIVES

To examine the contribution of live and pasteurized A. muciniphila to defend against the intestinal pathogen Salmonella Typhimurium in a streptomycin-treated mouse model of infection.

METHODS

C57B6J mice were pretreated with phosphate-buffered saline (PBS), live Akkermansia muciniphila (AKK), and pasteurized A. muciniphila (pAKK) for two weeks, then mice were infected by S. Typhimurium SL 1344. 16S rRNA-based gut microbiota analysis was performed before and after infection. Bacterial counts in feces and tissues, histopathological analysis, gut barrier-related gene expression, and antimicrobial peptides were examined. Co-housing was performed to examine the role of microbiota in the change of susceptibility of mice to infection.

RESULTS

AKK and pAKK markedly decreased Salmonella fecal and systemic burdens and reduced inflammation during infection. Notably, further characterization of AKK and pAKK protective mechanisms revealed different candidate protective pathways. AKK promoted gutbarrier gene expression and the secretion of antimicrobial peptides, and co-housing studies suggested that AKK-associated microbial community played a role in attenuating infection. Moreover, pAKK had a positive effect on NLRP3 in infected mice. We verified that pretreatment of pAKK could promote the expression of NLRP3, and enhance the antimicrobial activity of macrophage, likely through increasing the production of reactive oxygen (ROS), nitric oxide (NO), and inflammatory cytokines.

CONCLUSION

Our study demonstrates that live or pasteurized A. muciniphila can be effective preventive measures for alleviating S. Typhimurium-induced disease, highlighting the potential of developing Akkermansia-based probiotics or postbiotics for the prevention of Salmonellosis.

Bifidobacterium adolescentis orchestrates CD143+ cancer-associated fibroblasts to suppress colorectal tumorigenesis by Wnt signaling-regulated GAS1

BACKGROUND

The interplay between gut microbiota and tumor microenvironment (TME) in the pathogenesis of colorectal cancer (CRC) is not well explored. Here, we elucidated the functional role of Bifidobacterium adolescentis (B.a) on CRC and investigated its possible mechanism on the manipulation of cancer-associated fibroblasts (CAFs) in CRC.

METHODS

Different CRC animal models and various cell line models were established to explore the function of B.a on CRC. The single-cell RNA sequencing (scRNA-seq) or flow cytometry was used to detect the cell subsets in the TME of CRC. Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), or immunofluorescence staining were performed to examine the activation of Wnt signaling and growth arrest specific 1 (GAS1) on CD143+ CAFs. Chromatin immunoprecipitation quantitative real-time PCR (CHIP-qPCR) was performed to investigate the regulation of transcription factor 4 (TCF4) on GAS1. Multi-immunofluorescence assay examined the expression level of CD143 and GAS1 on tissue microarray.

RESULTS

We found that B.a abundance was significantly reduced in CRC patients from two independent cohorts and the bacteria database of GMrepo. Supplementation with B.a suppressed ApcMin/+ spontaneous or AOM/DSS-induced tumorigenesis in mice. scRNA-seq revealed that B.a facilitated a subset of CD143+ CAFs by inhibiting the infiltration of Th2 cells, while promoting the TNF-alpha+ B cells in TME. CD143+ CAFs highly expressed GAS1 and exhibited tumor suppressive effect. Mechanistically, GAS1 was activated by the Wnt/β-catenin signaling in CD143+ CAFs. B.a abundance was correlated with the expression level of CD143 and GAS1. The level of CD143+ CAFs predicted the better survival outcome in CRC patients.

CONCLUSIONS

These results highlighted that B.a induced a new subset of CD143+ CAFs by Wnt signaling-regulated GAS1 to suppress tumorigenesis and provided a novel therapeutic target for probiotic-based modulation of TME in CRC.

Exploring probiotic effector molecules and their mode of action in gut-immune interactions

Probiotics, live microorganisms that confer health benefits when consumed in adequate amounts, have gained significant attention for their potential therapeutic applications. The beneficial effects of probiotics are believed to stem from their ability to enhance intestinal barrier function, inhibit pathogens, increase beneficial gut microbes, and modulate immune responses. However, clinical studies investigating the effectiveness of probiotics have yielded conflicting results, potentially due to the wide variety of probiotic species and strains used, the challenges in controlling the desired number of live microorganisms, and the complex interactions between bioactive substances within probiotics. Bacterial cell wall components, known as effector molecules, play a crucial role in mediating the interaction between probiotics and host receptors, leading to the activation of signaling pathways that contribute to the health-promoting effects. Previous reviews have extensively covered different probiotic effector molecules, highlighting their impact on immune homeostasis. Understanding how each probiotic component modulates immune activity at the molecular level may enable the prediction of immunological outcomes in future clinical studies. In this review, we present a comprehensive overview of the structural and immunological features of probiotic effector molecules, focusing primarily on Lactobacillus and Bifidobacterium. We also discuss current gaps and limitations in the field and propose directions for future research to enhance our understanding of probiotic-mediated immunomodulation.

Mode of action of Akkermansia muciniphila in the intestinal dialogue: role of extracellular proteins, metabolites and cell envelope components

Akkermansia muciniphila is a promising next-generation beneficial microbe due to its natural presence in the mucus layer of the gut, its symbiotic ability to degrade mucus, and its capacity to improve the intestinal barrier function. A. muciniphila is able to counteract weight gain and immuno-metabolic disturbances in several animal models. Many of these disorders, including obesity and auto-immune diseases, have been associated with decreased gut barrier function and consequent increased inflammation. Since A. muciniphila was found to normalize these changes and strengthen the gut barrier function, it is hypothesized that other beneficial effects of A. muciniphila might be caused by this restoration. In search for A. muciniphila's mode of action in enhancing the gut barrier function and promoting health, we reasoned that secreted components or cell envelope components of A. muciniphila are interesting candidates as they can potentially reach and interact with the epithelial barrier. In this review, we focus on the potential mechanisms through which A. muciniphila can exert its beneficial effects on the host by the production of extracellular and secreted proteins, metabolites and cell envelope components. These products have been studied in isolation for their structure, signaling capacity, and in some cases, also for their effects in preclinical models. This includes the protein known as Amuc_1100, which we here rename as pilus-associated signaling (PAS) protein , the P9 protein encoded by Amuc_1631, the short-chain fatty acids acetate and propionate, and cell envelope components, such as phosphatidylethanolamine and peptidoglycan.

Unveiling and harnessing the human gut microbiome in the rising burden of non-communicable diseases during urbanization

The world is witnessing a global increase in the urban population, particularly in developing Asian and African countries. Concomitantly, the global burden of non-communicable diseases (NCDs) is rising, markedly associated with the changing landscape of lifestyle and environment during urbanization. Accumulating studies have revealed the role of the gut microbiome in regulating the immune and metabolic homeostasis of the host, which potentially bridges external factors to the host (patho-)physiology. In this review, we discuss the rising incidences of NCDs during urbanization and their links to the compositional and functional dysbiosis of the gut microbiome. In particular, we elucidate the effects of urbanization-associated factors (hygiene/pollution, urbanized diet, lifestyles, the use of antibiotics, and early life exposure) on the gut microbiome underlying the pathogenesis of NCDs. We also discuss the potential and feasibility of microbiome-inspired and microbiome-targeted approaches as novel avenues to counteract NCDs, including fecal microbiota transplantation, diet modulation, probiotics, postbiotics, synbiotics, celobiotics, and precision antibiotics.