Microbiota triggers STING-type I IFN-dependent monocyte reprogramming of the tumor microenvironment

Role of gut microbiome in suppression of cancers

The pathogenesis of cancer is closely related to the disruption of homeostasis in the human body. The gut microbiome plays crucial roles in maintaining the homeostasis of its host throughout lifespan. In recent years, a large number of studies have shown that dysbiosis of the gut microbiome is involved in the entire process of cancer initiation, development, and prognosis by influencing the host immune system and metabolism. Some specific intestinal bacteria promote the occurrence and development of cancers under certain conditions. Conversely, some other specific intestinal bacteria suppress the oncogenesis and progression of cancers, including inhibiting the occurrence of cancers, delaying the progression of cancers and boosting the therapeutic effect on cancers. The promoting effects of the gut microbiome on cancers have been comprehensively discussed in the previous review. This article will review the latest advances in the roles and mechanisms of gut microbiome in cancer suppression, providing a new perspective for developing strategies of cancer prevention and treatment.

Decoding the role of intratumoral microbiota in gastric cancer

Intratumoral microbiota are increasingly recognized for their impact on gastric cancer, with growing evidence highlighting their complexity and significance. This review synthesizes current knowledge on the origins, heterogeneity, detection, and mechanistic roles of intratumoral microbiota in gastric carcinogenesis. In gastric cancer, intratumoral microbiota can originate from mucosal disruption and may migrate from normal adjacent tissues or be influenced by the TME. It exhibits spatial and functional heterogeneity within gastric cancer. Despite challenges in the detection of intratumoral microbiota, advances in deep sequencing and spatial omics have enhanced our understanding of microbial diversity and functionality. Mechanistically, intratumoral microbiota influence gastric cancer development through genetic and epigenetic alterations, signaling pathway modulation, metabolic reprogramming, and regulation of chronic inflammation and immune responses. These insights underscore the microbiota's dual function in both promoting and hindering tumor advancement. Therapeutically, the microbiota's impact on chemotherapy resistance and immune modulation presents opportunities for novel interventions. Integrating microbiome analysis into cancer research and leveraging microbial therapies may enable more effective, personalized treatment strategies. Future research should further elucidate the intricate microbe-tumor interactions to advance clinical applications and improve outcomes for gastric cancer patients.

Nutritional strategies in oncology: The role of dietary patterns in modulating tumor progression and treatment response

Dietary interventions can influence tumor growth by restricting tumor-specific nutritional requirements, altering the nutrient availability in the tumor microenvironment, or enhancing the cytotoxicity of anticancer drugs. Metabolic reprogramming of tumor cells, as a significant hallmark of tumor progression, has a profound impact on immune regulation, severely hindering tumor eradication. Dietary interventions can modify tumor metabolic processes to some extent, thereby further improving the efficacy of tumor treatment. In this review, we emphasize the impact of dietary patterns on tumor progression. By exploring the metabolic differences of nutrients in normal cells versus cancer cells, we further clarify how dietary patterns influence cancer treatment. We also discuss the effects of dietary patterns on traditional treatments such as immunotherapy, chemotherapy, radiotherapy, and the gut microbiome, thereby underscoring the importance of precision nutrition.

Akkermansia muciniphila restrains type 1 diabetes onset by eliciting cDC2 and Treg cell differentiation in NOD and STZ-induced experimental models

AIMS

Akkermansia muciniphila (A. muciniphila), a Gram-negative anaerobic mucus-layer-degrading bacterium found in the intestinal mucosa, exhibits potential as a probiotic, showing promise in mitigating autoimmune and chronic inflammatory diseases. This study aims to investigate whether A. muciniphila supplementation might confer protection against type 1 diabetes (T1D) and to elucidate the immunological pathways through which it exerts its beneficial effects.

MATERIALS AND METHODS

Non-obese diabetic (NOD) mice and streptozotocin (STZ)-induced type 1 diabetes (T1D) models were used to evaluate the protective effects of A. muciniphila during T1D course. Body weight, blood glucose levels, and T1D incidence were monitored. Immune responses in the pancreas, pancreatic (PLN) and cecal lymph nodes (CLN) and bone marrow-derived dendritic cells (BMDC) were evaluated by flow cytometry and ELISA.

KEY FINDINGS

Viable A. muciniphila supplementation conferred protection against T1D onset in STZ-induced T1D and NOD mouse models. T1D modulation by A. muciniphila in the STZ model was independent of the gut microbiota, and it was associated with increased tolerogenic type-2 dendritic cells (SIRP-α+CD11b+CD103+) and regulatory T (Treg) cells in PLN and pancreas. BMDC differentiated in the presence of A. muciniphila exhibited a tolerogenic profile and induced Treg cell generation in vitro. A. muciniphila-induced protection in T1D outcome was abrogated in FOXP3-DTR mice depleted of Treg cells, indicating that its mechanism of action is dependent on the CD4+Foxp3+ Treg cells.

SIGNIFICANCE

A. muciniphila supplementation attenuates T1D development in mice by modulating the tolerogenic immune response and is a promising new therapeutic tool for this autoimmune disease.

Multifunctional nanoparticles and collagenase dual loaded thermosensitive hydrogel system for enhanced tumor-penetration, reversed immune suppression and photodynamic-immunotherapy

Breast cancer is the most prevalent and lethal malignancy among females, with a critical need for safer and less invasive treatments. Photodynamic therapy (PDT) can effectively eliminate tumor cells with minimal side effects. Furthermore, the combination of PDT and immunotherapy using nanoparticles has shown promise in treating both primary and distant metastatic tumor cells. Therefore, this study proposes applying the PDT-immunotherapy combination to breast cancer treatment. However, the low immunogenicity characteristic of "cold" tumors in part of breast cancer significantly diminishes therapeutic efficacy. To address this challenge, here, a nano-gel system (designated as HCSC-gel) is constructed, which co-delivers a mitochondria-targeted photosensitizer and a STING agonist, capable of robustly activating "cold" tumor immunity. This system is further enhanced by collagenase (CN) to improve therapeutic outcomes. Upon injection into the primary tumor site, HCSC-gel rapidly forms a gel matrix, releasing CN to degrade the tumor extracellular matrix and facilitate the penetration of photosensitizers, STING agonists, and oxygen into the tumor tissue. Under laser irradiation, PDT and STING-mediated immune responses are activated, reversing the low immunogenicity of breast cancer and effectively treating both primary and metastatic lesions. This HCSC-gel nano hydrogel delivery platform is anticipated to provide novel insights for the clinical management of breast cancer and other low immunogenic "cold" tumors, offering significant benefits to patients.

Interaction between gut microbiota and T cell immunity in colorectal cancer

This review delves into the complex and multi-layered mechanisms that govern the interaction between gut microbiota and T cells in the context of colorectal cancer (CRC), revealing a novel "microbiota-immune regulatory landscape" within the tumor microenvironment. As CRC progresses, the gut microbiota experiences a significant transformation in both its composition and metabolic patterns. On one hand, specific microbial entities within the gut microbiota can directly engage with T cells, functioning as "immunological triggers" that shape T-cell behavior. Simultaneously, microbial metabolites, such as short-chain fatty acids and bile acids, serve as "molecular regulators" that intricately govern T-cell function and differentiation, fine-tuning the immune response. On the other hand, the quorum-sensing mechanism, a recently recognized communication network among bacteria, also plays a pivotal role in orchestrating T-cell immunity. Additionally, the gut microbiota forms an intriguing connection with the neuro-immune regulatory axis, a largely unexplored "territory" in CRC research. Regarding treatment strategies, a diverse array of intervention approaches-including dietary modifications, the utilization of probiotics, bacteriophages, and targeted antibiotic therapies-offer promising prospects for restoring the equilibrium of the gut microbiota, thereby acting as "ecosystem renovators" that impede tumor initiation and progression. Nevertheless, the current research landscape in this field is fraught with challenges. These include significant variations in microbial composition, dietary preferences, and tumor microenvironments among individuals, a lack of large-scale cohort studies, and insufficient research that integrates tumor mutation analysis, gut microbiota investigations, and immune microenvironment evaluations. This review emphasizes the necessity for future research efforts to seamlessly incorporate multiple factors and utilize bioinformatics analysis to construct a more comprehensive "interactive map" of the gut microbiota-T cell relationship in CRC. The aim is to establish a solid theoretical basis for the development of highly effective and personalized treatment regimens, ultimately transforming the therapeutic approach to CRC.

Gut and Intratumoral microbiota: Key to lung Cancer development and immunotherapy

Lung cancer is a common malignant tumor worldwide with high incidence and mortality rates. Previous studies have claimed that the microbial community plays an integral role in the development and progression of lung cancer. Emerging evidence reveals that gut flora plays a key role in cancer formation and evolution by participating in mechanisms such as metabolism, regulation of inflammation and immune response. Not only the gut flora, but also the presence of intratumoral microbiota may influence lung cancer progression through multiple mechanisms. These research advances suggest that intestinal flora and intratumoral microbiota may not only serve as potential biomarkers for lung cancer, but may also be targets for therapy. However, current studies on both in lung cancer are still limited. Given this, this study aimed to systematically review the latest findings on the major bacterial species of the intestinal flora and their possible protective or harmful roles in the formation, progression, and metastasis of lung cancer. In addition, we analyzed the potential mechanisms by which the intratumoral microbiota affected lung cancer and elaborated on the potential roles of the gut flora and its metabolites, as well as the intratumoral microbiota, in modulating the efficacy of immunotherapy in lung cancer.

Eukaryotic ADCY7 catalyzes the production of c-di-AMP to activate the NLRP3 inflammasome

Toll-like receptor 9 (TLR9) agonists cause activation of nucleotide-binding domain, leucine-rich repeat protein 3 (NLRP3) inflammasomes but the mechanism is not clear. We found that there is a second signal downstream of TLR9 that induces NLRP3 inflammasome activation. Through screening, adenylate cyclase 7 (ADCY7) was found to be an essential regulator of this process. In cells with Adcy7 deficiency, TLR9 agonists were no longer able to activate the NLRP3 inflammasome. ADCY7 not only catalyzes the generation of cyclic adenosine monophosphate (cAMP) but also catalyzes the synthesis of its dimeric form (c-di-AMP). Moreover, c-di-AMP promotes assembly and maturation of the inflammasome by directly binding to NLRP3. Cells with Adcy7 deletion or mutations impacting enzymatic activity cannot produce c-di-AMP. The survival of Adcy7-deficient mice in acute liver injury was also improved. In summary, we found that ADCY7 is required for NLRP3 inflammasome activation downstream of TLR9 by catalyzing the generation of c-di-AMP, which may serve as a target for controlling inflammatory responses in sterile infections.

The interplay between gut microbiota, antibiotics, and immune checkpoint inhibitors in patients with cancer: A narrative review with biological and clinical aspects

Immune checkpoint inhibitors (ICIs) targeting the programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) pathways have revolutionized cancer therapy. However, primary and secondary resistance to ICI pose significant challenges. Recent studies underscore the critical role of gut microbiota (GM) in modulating ICI efficacy by shaping host immune responses and regulating the tumor microenvironment (TME). The composition of the GM has been linked to ICI treatment outcomes, with certain microbial taxa, such as Faecalibacterium spp., Bifidobacterium spp., Eubacterium spp., Roseburia spp., and Akkermansia muciniphila, associated with favorable responses. Mechanistically, the GM affects immune responses via multiple pathways, including induction of T cell differentiation, promotion of anti- or proinflammatory cytokine environments, and enhancement of T cell priming and effector functions. Moreover, microbial-derived metabolites play a role in shaping tumor immune responses and influencing ICI efficacy. Antibiotic treatment can disrupt GM diversity and composition (gut dysbiosis), potentially diminishing ICI effectiveness. A deeper understanding of the interplay between GM, antibiotic treatment, and ICI efficacy is crucial for developing personalized therapeutic strategies to improve patient outcomes. Herein, we review current evidence on the association between specific microbial taxa and tumor immunosurveillance, the impact of antibiotics on the GM composition and immune modulation, and its implications for ICI therapy efficacy.

Multimodal Regulation of Dendritic Cells via Mineralized Vaccines for Postsurgical Tumor Relapse Prevention

The regulation of dendritic cell (DC) function is pivotal for augmenting the immune response of traditional tumor therapy, particularly in mitigating postsurgical tumor relapse. Unfortunately, DC functionality is often compromised in the postsurgical microenvironment, leading to immune tolerance and tumor progression. To address these challenges, we developed a personalized cancer vaccine, Cell@CaP, which utilizes inactivated autologous tumor cells coated with a calcium phosphate shell. This innovative vaccine incorporates cyclic GMP-AMP (cGAMP), a STING agonist, and calcium ions (Ca2+) to boost DCs activation and antigen presentation. The Cell@CaP vaccine leverages high mechanical hardness, intact tumor antigens, and the release of cGAMP and Ca2+ to activate DCs through multiple pathways. Upon interaction with DCs, the vaccine triggers the Piezo1 mechanosensitive channel, inducing a Ca2+ influx. This mechanical stimulation, combined with the release of cGAMP and tumor antigens, activates the cGAS-STING, PI3K-Akt, and RhoA-MYPT1 signaling pathways. These synergistic effects enhance the expression of costimulatory molecules and promote the secretion of pro-inflammatory cytokines (interferon-β and tumor necrosis factor-α). In a postsurgical osteosarcoma model, the combination of Cell@CaP with radiotherapy significantly inhibited primary tumor relapse and suppressed distant lung metastases. This multimodal vaccine strategy integrates mechanical, chemical, and immunological cues into a single platform, offering a promising approach to enhance DCs functionality and activate robust antitumor immunity. The study highlights the potential of Cell@CaP as a personalized immunotherapy for preventing postsurgical tumor relapse.

Tumor-associated macrophages remodel the suppressive tumor immune microenvironment and targeted therapy for immunotherapy

Despite the significant advances in the development of immune checkpoint inhibitors (ICI), primary and acquired ICI resistance remains the primary impediment to effective cancer immunotherapy. Residing in the tumor microenvironment (TME), tumor-associated macrophages (TAMs) play a pivotal role in tumor progression by regulating diverse signaling pathways. Notably, accumulating evidence has confirmed that TAMs interplay with various cellular components within the TME directly or indirectly to maintain the dynamic balance of the M1/M2 ratio and shape an immunosuppressive TME, consequently conferring immune evasion and immunotherapy tolerance. Detailed investigation of the communication network around TAMs could provide potential molecular targets and optimize ICI therapies. In this review, we systematically summarize the latest advances in understanding the origin and functional plasticity of TAMs, with a focus on the key signaling pathways driving macrophage polarization and the diverse stimuli that regulate this dynamic process. Moreover, we elaborate on the intricate interplay between TAMs and other cellular constituents within the TME, that is driving tumor initiation, progression and immune evasion, exploring novel targets for cancer immunotherapy. We further discuss current challenges and future research directions, emphasizing the need to decode TAM-TME interactions and translate preclinical findings into clinical breakthroughs. In conclusion, while TAM-targeted therapies hold significant promise for enhancing immunotherapy outcomes, addressing key challenges-such as TAM heterogeneity, context-dependent plasticity, and therapeutic resistance-remains critical to achieving optimal clinical efficacy.

Microbiota mechanisms in cancer progression and therapy

The composition of the microbiota in patients has been shown to correlate with cancer progression and response to therapy, highlighting unique opportunities to improve patient outcomes. In this review, we discuss the challenges and advancements in understanding the chemical mechanisms of specific microbiota species, pathways, and molecules involved in cancer progression and treatment. We also describe the modulation of cancer and immunotherapy by the microbiota, along with approaches for investigating microbiota enzymes and metabolites. Elucidating these specific microbiota mechanisms and molecules should offer new opportunities for developing enhanced diagnostics and therapeutics to improve outcomes for cancer patients. Nonetheless, many microbiota mechanisms remain to be determined and require innovative chemical genetic approaches.

The aspartate superpathway in gut microbiota-related metabolic pathways mediates immune cell protection against COPD and IPF: a Mendelian randomization analysis

BACKGROUND

Both genetic and environmental factors can influence idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) development. The gut microbiota plays crucial roles in maintaining tissue homeostasis. Dysregulation of the gut microbiota can result in disease. However, whether the alteration of the gut microbiota influences IPF and COPD remains unknown.

RESEARCH QUESTION

What is the causal relationship between IPF, COPD and the gut microbiota-related metabolic pathways? What are the potential intermediate mediators in this relationship?

STUDY DESIGN AND METHODS

Intersect the gut microbiota and its metabolic pathways associated with IPF and COPD. Utilizing summary data from GWAS in public databases, a two-sample Mendelian randomization (MR) analysis was conducted on the gut microbiota-related metabolic pathway, the aspartate superpathway, in relation to IPF and COPD. Furthermore, we employed a two-step MR to quantify the proportion of influence mediated by monocytes and cDCs on the aspartate superpathway in relation to IPF and COPD.

RESULTS

The MR analysis found that the aspartate superpathway decreased the risk of developing IPF and COPD. Monocytes and cDCs acted as intermediary substances, participating in this with influence proportions of 7.88% and 6.27%, respectively.

INTERPRETATION

There is a causal link between the gut microbiota-related metabolic pathway, the aspartate superpathway, and IPF and COPD, where the influence is partially mediated by monocytes and cDCs. In clinical practice, we increase the focus on gut microbiota-mediated immune cells in relation to IPF and COPD.

Bacteria-responsive cytoderm drug delivery systems

Signs of bacterial activities have been reported in a variety of disease models. Here, we extracted plant cytoderm ghosts (PCGs) from plant cells, acting as bacteria-responsive drug delivery systems (DDSs) that release drugs specifically in response to the presence or activity of bacteria. Cellulose, which is one of the main components of PCGs, can be degraded in the presence of specialized bacteria that secrete enzymes to convert the cellulose into simpler sugars, thus breaking down the structure of PCGs to release the loaded drugs. In our study, PCGs loaded with ciprofloxacin (PCG@CIP) could effectively inhibit the proliferation and retention of bacteria at the infection site, and improve the local wound microenvironment to accelerate wound repair. In addition, the PCG platform with anticancer drugs could effectively regulate the progression of tumor growth. Therefore, we report a new drug delivery system that responds to the microbiota based on plant cytoderm, providing a new option for drug responsive delivery.

PCK1 inhibits cGAS-STING activation by consumption of GTP to promote tumor immune evasion

Hypoxia induces immunosuppressive phenotypes in tumor cells even in the presence of cytosolic DNA accumulation. The mechanisms by which tumor cells suppress hypoxia-induced cGAS-STING activation for immune evasion remain largely unclear. Here, we demonstrate that hypoxic stimulation induces JNK1/2-mediated S151 phosphorylation of phosphoenolpyruvate carboxykinase 1 (PCK1), a rate-limiting enzyme in gluconeogenesis. This phosphorylation triggers the interaction between PCK1 and cGAS. The PCK1 associated with cGAS competitively consumes GTP, a substrate shared by both PCK1 and cGAS. Consequently, PCK1 inhibits GTP-dependent cGAS activation and subsequent STING-promoted immune cell infiltration and activation in the tumor microenvironment, leading to promoted tumor growth in mice. The blockade of PCK1 function, in combination with anti-PD-1 antibody treatment, exhibits an additive therapeutic effect on tumor growth. Additionally, PCK1 S151 phosphorylation is inversely correlated with cGAS-STING activation in human breast cancer specimens and patient survival. These findings reveal a novel regulation of cGAS-STING pathway and uncover the metabolic control of immune response in tumor cells.

Single-cell transcriptomic analysis reveals gut microbiota-immunotherapy synergy through modulating tumor microenvironment

The gut microbiota crucially regulates the efficacy of immune checkpoint inhibitor (ICI) based immunotherapy, but the underlying mechanisms remain unclear at the single-cell resolution. Using single-cell RNA sequencing and subsequent validations, we investigate gut microbiota-ICI synergy by profiling the tumor microenvironment (TME) and elucidating critical cellular interactions in mouse models. Our findings reveal that intact gut microbiota combined with ICIs may synergistically increase the proportions of CD8+, CD4+, and γδ T cells, reduce glycolysis metabolism, and reverse exhausted CD8+ T cells into memory/effector CD8+ T cells, enhancing antitumor response. This synergistic effect also induces macrophage reprogramming from M2 protumor Spp1+ tumor-associated macrophages (TAMs) to Cd74+ TAMs, which act as antigen-presenting cells (APCs). These macrophage subtypes show a negative correlation within tumors, particularly during fecal microbiota transplantation. Depleting Spp1+ TAMs in Spp1 conditional knockout mice boosts ICI efficacy and T cell infiltration, regardless of gut microbiota status, suggesting a potential upstream role of the gut microbiota and highlighting the crucial negative impact of Spp1+ TAMs during macrophage reprogramming on immunotherapy outcomes. Mechanistically, we propose a γδ T cell-APC-CD8+ T cell axis, where gut microbiota and ICIs enhance Cd40lg expression on γδ T cells, activating Cd40 overexpressing APCs (e.g., Cd74+ TAMs) through CD40-CD40L-related NF-κB signaling and boosting CD8+ T cell responses via CD86-CD28 interactions. These findings highlight the potential importance of γδ T cells and SPP1-related macrophage reprogramming in activating CD8+ T cells, as well as the synergistic effect of gut microbiota and ICIs in immunotherapy through modulating the TME.

Nervous system-gut microbiota-immune system axis: future directions for preventing tumor

Tumor is one of the leading causes of death worldwide. The occurrence and development of tumors are related to multiple systems and factors such as the immune system, gut microbiota, and nervous system. The immune system plays a critical role in tumor development. Studies have also found that the gut microbiota can directly or indirectly affect tumorigenesis and tumor development. With increasing attention on the tumor microenvironment in recent years, the nervous system has emerged as a novel regulator of tumor development. Some tumor therapies based on the nervous system have also been tested in clinical trials. However, the nervous system can not only directly interact with tumor cells but also indirectly affect tumor development through the gut microbiota. The nervous system-mediated gut microbiota can regulate tumorigenesis, growth, invasion, and metastasis through the immune system. Here, we mainly explore the potential effects of the nervous system-gut microbiota-immune system axis on tumorigenesis and tumor development. The effects of the nervous system-gut microbiota-immune system axis on tumors involve the nervous system regulating immune cells through the gut microbiota, which can prevent tumor development. Meanwhile, the direct effects of the gut microbiota on tumors and the regulation of the immune system by the nervous system, which can affect tumor development, are also reviewed.

Gut microbiota in cancer initiation, development and therapy

Cancer has long been associated with genetic and environmental factors, but recent studies reveal the important role of gut microbiota in its initiation and progression. Around 13% of cancers are linked to infectious agents, highlighting the need to identify the specific microorganisms involved. Gut microbiota can either promote or inhibit cancer growth by influencing oncogenic signaling pathways and altering immune responses. Dysbiosis can lead to cancer, while certain probiotics and their metabolites may help reestablish micro-ecological balance and improve anti-tumor immune responses. Research into targeted approaches that enhance therapy with probiotics is promising. However, the effects of probiotics in humans are complex and not yet fully understood. Additionally, methods to counteract harmful bacteria are still in development. Early clinical trials also indicate that modifying gut microbiota may help manage side effects of cancer treatments. Ongoing research is crucial to understand better how gut microbiota can be used to improve cancer prevention and treatment outcomes.

The carcinogenic metabolite acetaldehyde impairs cGAS activity to negatively regulate antiviral and antitumor immunity

The cGAS-MITA/STING pathway plays critical roles in both host defense against DNA virus and intrinsic antitumor immunity by sensing viral genomic DNA or dis-located mitochondrial/cellular DNA. Whether carcinogenic metabolites can target the cGAS-MITA axis to promote tumorigenesis is unknown. In this study, we identified acetaldehyde, a carcinogenic metabolite, as a suppressor of the cGAS-MITA pathway. Acetaldehyde inhibits the DNA virus herpes simplex virus 1 (HSV-1)- and transfected DNA-triggered but not cGAMP-induced activation of downstream components and induction of downstream effector genes. Mechanistically, acetaldehyde impairs the binding of cGAS to DNA as well as the phase separation of the cGAS-DNA complex in cells. In mouse models, acetaldehyde inhibits antiviral cytokine production, promotes viral replication and lethality upon HSV-1 infection. In a colorectal tumor xenograft model, acetaldehyde promotes tumor growth and inhibits CD8+ T cell infiltration by targeting cGAS in both the tumor cells and immune cells in mice. Bioinformatic analysis indicates that expression of acetaldehyde dehydrogenase 2 (ALDH2), which converts acetaldehyde to acetic acid, is negatively correlated with stimulatory immune signatures in clinical colorectal tumors, and higher ALDH2 expression exhibits better prognosis of colorectal cancer patients. Collectively, our results suggest that acetaldehyde impairs cGAS activity to inhibit the cGAS-MITA axis, which contributes to its effects on carcinogenesis.

Microbial metabolite ammonia disrupts TGF-β signaling to promote colon cancer

Colorectal cancer (CRC) is rising alarmingly in younger populations, potentially arising from factors such as obesity, pro-inflammatory gut microbiome and the accumulation of toxic metabolites. However, how metabolites such as ammonia impact key signaling pathways to promote CRC remains unclear. Our study investigates a critical link between gut microbiome alterations, ammonia, and their toxic effects on the TGF-β signaling pathway, driving CRC progression. We observe altered microbial populations in an obesity-induced mouse model of cancer, where ammonia promotes caspase-3-mediated cleavage of the SMAD3 adaptor βII-spectrin (SPTBN1). Cleaved SPTBN1 fragments form adducts with ammonia that induce pro-inflammatory cytokine expression and disrupt TGF-β signaling. Extending from AlphaFold docking simulations, we identified that ammonia interacts with N-terminal SPTBN1 potentially through residues D81, Y556, S663, Y666, N986, and D1177 to form hydrogen bonds that disrupt downstream SMAD3 signaling, altering TGF-β signaling to a protumorigenic phenotype. Blocking SPTBN1, through an SPTBN1-specific siRNA blocks ammonia toxicity and restores normal SMAD3/TGF-β signaling by reducing the abundance of SPTBN1 cleaved fragments in SW480 and Caco-2 (CRC) cell lines. In addition, our research establishes crosstalk between TGF-β signaling and a microbial sensor, carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), which is significantly overexpressed in CRC patients. We identified CEACAM1-SPTBN1 interactions at specific residues (E517 and Y520) within the immunoreceptor tyrosine-based inhibitory motif (ITIM) of CEACAM1 cytoplasmic domain, identifying distinguishing a potential axis that is harnessed by the altered microbiome. Our study identifies mechanistic insights into how microbial metabolites target TGF-β as a major signaling pathway to promote CRC.

The human microbiome: redefining cancer pathogenesis and therapy

The human microbiome has always been an important determinant of health and recently, its role has also been described in cancer. The altered microbiome could aid cancer progression, modulate chemoresistance and significantly alter drug efficacy. The broad implications of microbes in cancer have prompted researchers to investigate the microbe-cancer axis and identify whether modifying the microbiome could sensitize cancer cells for therapy and improve the survival outcome of cancer patients. The preclinical data has shown that enhancing the number of specific microbial species could restore the patients' response to cancer drugs and the microbial biomarkers may play a vital role in cancer diagnostics. The elucidation of detailed interactions of the human microbiota with cancer would not only help identify the novel drug targets but would also enhance the efficacy of existing drugs. The field exploring the emerging roles of microbiome in cancer is at a nascent stage and an in-depth scientific perspective on this topic would make it more accessible to a wider audience. In this review, we discuss the scientific evidence connecting the human microbiome to the origin and progression of cancer. We also discuss the potential mechanisms by which microbiota affects initiation of cancer, metastasis and chemoresistance. We highlight the significance of the microbiome in therapeutic outcome and evaluate the potential of microbe-based cancer therapy.

Involvement of Pruritus, Gut Dysbiosis and Histamine-Producing Bacteria in Paraneoplastic Syndromes

Background/Objectives: Paraneoplastic syndromes (PNS), characterized by a large diversity of symptoms, may sometimes be the first clinical feature of a severe underlying disorder such as cancer. Methods: We report the case of a middle-aged male patient with no significant previous medical history, a nonsmoker or alcohol heavy drinker, complaining about generalized, recently onset itch. Given no reasonable explanation of pruritus after dermatological consultation and the unsatisfactory response to treatment, the patient was referred to gastroenterology with the suspicion of a cholestatic liver disease. Results: The abdominal ultrasound examination revealed gallstones and no dilation of the biliary tree. Numerous tests were run and came out negative, except for the slight elevation of C-reactive protein, mild dyslipidemia, and positivity for H. pylori antigen. The gut microbiota displayed important dysbiosis with a significant increase in the histamine-producing bacteria. Given this chronic pruritus became suspicious, thorax and abdominal CT were recommended and performed soon after. A large right mid-thoracic tumor image was found. Bronchoscopy came out negative for a tumor. After the CT-guided biopsy, the tumor turned out not to be a lymphoma, but a non-small cell lung carcinoma (NSCLC). Conclusions: Chronic pruritus was not associated with cholestasis in a patient with gallstone disease, but rather with a PNS, as the first clinical manifestation of NSCLC, triggering many diagnostic and therapeutic challenges.

Carvedilol sensitizes chemotherapy by targeting STING to boost anti-tumor immunity

The stimulator of interferon genes (STING)-mediated type I interferon (IFN) response is critical for mounting anti-tumor immunity and sensitizing chemotherapy by remodeling the tumor immune microenvironment. However, no clinically available drugs have been applied for STING activation. Based on high-throughput screening of small-molecule microarrays, we found that carvedilol, an adrenergic receptor blocker used to treat essential hypertension and symptomatic heart failure, is a STING activator. Mechanistically, carvedilol interacts with STING at threonine 263 and enhances its dimerization. Importantly, carvedilol enhances the therapeutic effect of etoposide in both the allografted tumor model and patient-derived tumor-like cell clusters (PTCs) by promoting etoposide-induced STING activation. Our findings identify carvedilol as a STING activator and provide a theoretical basis for combining carvedilol and etoposide in cancer therapy.

Gut microbiota and gastrointestinal tumors: insights from a bibliometric analysis

Introduction

Despite the growing number of studies on the role of gut microbiota in treating gastrointestinal tumors, the overall research trends in this field remain inadequately characterized.

Methods

A bibliometric analysis was conducted using publications retrieved from the Web of Science Core Collection (up to September 30, 2024). Analytical tools including VOSviewer, CiteSpace, and an online bibliometric platform were employed to evaluate trends and hotspots.

Results

Analysis of 1,421 publications revealed significant geographical disparities in research output, with China and the United States leading contributions. Institutionally, the University of Adelaide, Zhejiang University, and Shanghai Jiao Tong University were prominent contributors. Authorship analysis identified Hannah R. Wardill as the most prolific author, while the International Journal of Molecular Sciences emerged as a leading journal. Rapidly growing frontiers include "proliferation," "inhibition," "immunotherapy," "drug delivery," and "tumorigenesis."

Discussion

This study provides a comprehensive overview of research trends and highlights emerging directions, aiming to advance scientific and clinical applications of gut microbiota in gastrointestinal tumor therapy.

Lactobacillus acidophilus potentiates oncolytic virotherapy through modulating gut microbiota homeostasis in hepatocellular carcinoma

Oncolytic viruses (OVs) hold promise for cancer treatment. However, the antitumor efficacy is limited. Microbiota plays a pivotal role in cancer treatment and its impact on oncolytic virotherapy is unknown. Here, we show that VSVΔ51 has higher antitumor efficacy for hepatocellular carcinoma in the absence of microbiota in female mouse models. VSVΔ51 infection causes microbiota dysbiosis, increasing most of the gut bacteria abundance, while decreasing the commensal Lactobacillus. VSVΔ51 reduced intestinal expression of SLC20A1 that binds to Lactobacillus acidophilus (L. acidophilus) CdpA cell wall protein through IL6-JAK-STAT3 signaling, thereby attenuating attachment and colonization of L. acidophilus. L. acidophilus supplementation confers sensitivity to VSVΔ51 through restoring gut barrier integrity and microbiota homeostasis destroyed by VSVΔ51. In this work, we show that targeting microbiota homostasis holds substantial potential in improving therapeutic outcomes of oncolytic virotherapy.

Association of dietary inflammatory index, composite dietary antioxidant index and risk of death among adult cancer survivors: findings from the National Health and Nutrition Examination Survey 2001-2018

Background

The development and progression of cancer can be impacted by the nutrients and components contained in the diet. This research seeks to explore the relationship between the antioxidant and pro-inflammatory properties of diet and the risk of all-cause mortality among cancer survivors.

Methods

Adults aged 20 and above who had been diagnosed with cancer and participated in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018 were selected for this study. Their survival status was verified using death certificate information from the National Death Index. The study employed two established measures, the Composite Dietary Antioxidant Index (CDAI) and the Dietary Inflammatory Index (DII), to evaluate the antioxidant and inflammatory properties of participants' diets. A non-linear association between these two dietary indices and mortality was examined respectively using restricted cubic spline (RCS) regression. To quantify the relationship between the indices and mortality risk, multivariable Cox proportional hazards models were employed, generating hazard ratios and corresponding 95% confidence intervals. Furthermore, the study also explored the connection between the CDAI and DII.

Results

In this study, a total of 3,507 cancer survivors, representing an estimated 20,016,255 cancer survivors in the US, were included in the baseline analysis. The results showed that patients with lower DII or higher CDAI values had better survival rates. RCS regression revealed that both indicators showed linear relationships with all-cause mortality in the crude and adjusted models. It was consistently noted higher CDAI or lower DII was related to a reduced risk of all-cause mortality in cancer survivors in the Cox regression. Moreover, the subgroup analysis demonstrated that these associations hold true across various subgroups, lending credibility to the overall findings of the study. At last, an inverse correlation was observed between CDAI and DII in the diets of cancer survivors.

Conclusion

The research suggests that adopting a diet that low in pro-inflammatory foods and high in antioxidants may lower the all-cause mortality in cancer survivors. However, further prospective cohort studies are necessary to confirm these findings.

Unveiling the crossroads of STING signaling pathway and metabolic reprogramming: the multifaceted role of the STING in the TME and new prospects in cancer therapies

The cGAS-STING signaling pathway serves as a critical link between DNA sensing and innate immunity, and has tremendous potential to improve anti-tumor immunity by generating type I interferons. However, STING agonists have shown decreasing biotherapeutic efficacy in clinical trials. Tumor metabolism, characterized by aberrant nutrient utilization and energy production, is a fundamental hallmark of tumorigenesis. And modulating metabolic pathways in tumor cells has been discovered as a therapeutic strategy for tumors. As research concerning STING progressed, emerging evidence highlights its role in metabolic reprogramming, independent its immune function, indicating metabolic targets as a strategy for STING activation in cancers. In this review, we delve into the interplay between STING and multiple metabolic pathways. We also synthesize current knowledge on the antitumor functions of STING, and the metabolic targets within the tumor microenvironment (TME) that could be exploited for STING activation. This review highlights the necessity for future research to dissect the complex metabolic interactions with STING in various cancer types, emphasizing the potential for personalized therapeutic strategies based on metabolic profiling.

Unlocking the power of the microbiome for successful cancer immunotherapy

In recent years, evidence has shown that the gut microbiome significantly influences responses to immunotherapy. This has sparked interest in targeting it to improve therapy outcomes and predictions of response and toxicity. Research has demonstrated that dysbiosis, often resulting from antibiotic use, can diminish the effectiveness of immune checkpoint inhibitors, and this lack of efficacy could be linked to systemic inflammation. Certain bacterial species have been identified as having beneficial and harmful effects on immunotherapy in the clinic. While a clear consensus has yet to emerge on the optimal species for therapeutic use, introducing a new microbiome into immunotherapy-refractory patients may boost their chances of responding to further treatment attempts. State-of-the-art interventions targeting the microbiome-such as fecal microbiota transplantation-are being assessed clinically for their safety and potential to enhance treatment outcomes, with promising results. Additionally, the microbiome has been leveraged for its power to predict clinical outcomes using machine learning, and surprisingly, its predictive capability is comparable to that of other described multi-biomarker clinical scores. Here, we discuss developing knowledge concerning the microbiome's significance in cancer immunotherapy and outline future strategies for maximizing its potential in immuno-oncology.

Understanding the microbiome as a mediator of bladder cancer progression and therapeutic response

Bladder cancer (BCa) remains a significant source of morbidity and mortality. BCa is one of the most expensive tumors to treat, in part because of a lack of nonsurgical options. The recent advent of immunotherapy, alone or in combination with other compounds, has improved therapeutic options. Resistance to immunotherapy remains common, and many patients do not have durable response. Recent advances indicate immunotherapy efficacy may be tied in part to the endogenous bacteria present in our body, more commonly referred to as the microbiome. Laboratory and clinical data now support the idea that a healthy microbiome is critical to effective response to immunotherapy. At the same time, pathogenic interactions between the microbiome and immune cells can also serve to drive formation of tumors, increasing the complexity of these interactions. Given the rising importance of immunotherapy in BCa, understanding how we might be able to alter the microbiome to improve therapeutic efficacy offers a novel route to improved patient care. The goal of this review is to examine our current understanding of microbial interactions with the immune system and cancer with an emphasis on BCa. We will further attempt to define both current gaps in knowledge and future directions that may yield beneficial results to the field.

Friends close, enemies closer: the complex role of the microbiome in antitumor immunity

Immunotherapy has achieved remarkable advances in cancer treatment by harnessing the immune system to combat tumors, yet its effectiveness remains inconsistent across patients and tumor types. The microbiota, a diverse assemblage of microorganisms residing at host barrier surfaces, is pivotal in shaping immune responses. This review explores the direct and indirect mechanisms via which the microbiota modulates antitumor immune responses both locally within the tumor microenvironment and systemically by affecting distant tumors. We discuss recent findings linking microbiota-derived metabolites and microbiota-derived antigens with antitumor immunity and immunotherapy response. Additionally, we discuss recent advances in microbiome-based therapies, including fecal microbiota transplantation. We propose the use and development of new analytical techniques to further characterize the complex functions and interactions between the microbiome and immune system. To conclude, we outline recommendations for future research and therapeutic approaches to leverage the microbiome to improve current immunotherapies.

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

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

Effect of Helicobacter Pylori infection on immunotherapy for gastrointestinal cancer: a narrative review

Immunotherapy for gastrointestinal cancers has elicited considerable amount of attention as a viable therapeutic option for several cancer types. Gut microbiome as a whole plays a critical role in shaping immune responses and influencing cancer progression. Recent evidence suggests that Helicobacter pylori (H. pylori), may influence immunotherapy efficacy by modulating the tumor microenvironment. Infection with H. pylori is common as it affects approximately 50% of the global population and remains the leading risk factor for gastric cancer. Interestingly, recent clinical and preclinical data has associated H. pylori with colorectal cancer carcinogenesis. Gut microbiome appears to be a modulator of the relationship between the immune system, gastrointestinal cancer development and existing therapies. Infection with H. pylori may affect immunotherapy results in both gastroesophageal and colorectal cancer; favorable results were noticed in H. pylori positive patients with gastric cancer, while in colorectal cancer patients the pathogen seemed to impede immunotherapy's action. This article aims to review current data on the role of H. pylori in triggering gastric inflammation and cancer, as well as its potential involvement in colorectal cancer development. Additionally, it seeks to highlight the impact of H. pylori infection on the response to immunotherapy in gastrointestinal cancers.

Gut microbiota as a new target for anticancer therapy: from mechanism to means of regulation

In order to decipher the relationship between gut microbiota imbalance and cancer, this paper reviewed the role of intestinal microbiota in anticancer therapy and related mechanisms, discussed the current research status of gut microbiota as a biomarker of cancer, and finally summarized the reasonable means of regulating gut microbiota to assist cancer therapy. Overall, our study reveals that the gut microbiota can serve as a potential target for improving cancer management.

Targeting tumor monocyte-intrinsic PD-L1 by rewiring STING signaling and enhancing STING agonist therapy

STING is an important DNA sensing machinery in initiating immune response, yet therapies targeting STING have shown poor outcomes in clinical trials. Here, we reveal that STING signaling induces PD-L1hi tumor monocytes (Tu.Mons) that dominate the resistance against STING agonist therapy. Cell-intrinsic PD-L1, induced by the STING-IRF3-IFN-I axis, is identified as the driving factor for protumoral PD-L1hi Tu.Mons. Notably, TLR2-activated Tu.Mons resist STING-induced upregulation of cell-intrinsic PD-L1 and the associated protumoral functions. Mechanistically, TLR2 stimulation remodels STING signaling by facilitating STING and TRAF6 interaction, which suppresses the IRF3-IFN-I response and enhances NF-κB activation. Moreover, we demonstrate that combining STING agonists with TLR2 agonist pretreatment significantly improves antitumor efficacy in murine syngeneic and humanized models. Our findings uncover a protumoral aspect of STING activation mediated by cell-intrinsic PD-L1 and propose a promising strategy to boost antitumor immunity by fine-tuning STING signaling outputs.

Exploring effects of gut microbiota on tertiary lymphoid structure formation for tumor immunotherapy

Anti-tumor immunity, including innate and adaptive immunity is critical in inhibiting tumorigenesis and development of tumor. The adaptive immunity needs specific lymph organs such as tertiary lymphoid structures (TLSs), which are highly correlated with improved survival outcomes in many cancers. In recent years, with increasing attention on the TLS in tumor microenvironment, TLSs have emerged as a novel target for anti-tumor therapy. Excitingly, studies have shown the contribution of TLSs to the adaptive immune responses. However, it is unclear how TLSs to form and how to more effectively defense against tumor through TLS formation. Recent studies have shown that the inflammation plays a critical role in TLS formation. Interestingly, studies have also found that gut microbiota can regulate the occurrence and development of inflammation. Therefore, we here summarize the potential effects of gut microbiota- mediated inflammation or immunosuppression on the TLS formation in tumor environments. Meanwhile, this review also explores how to manipulate mature TLS formation through regulating gut microbiota/metabolites or gut microbiota associated signal pathways for anti-tumor immunity, which potentially lead to a next-generation cancer immunotherapy.

Facile integration of a binary nano-prodrug with αPD-L1 as a translatable technology for potent immunotherapy of TNBC

Immune checkpoint blockers (ICBs)-based immunotherapy is a favorable approach for efficient triple-negative breast cancer (TNBC) treatment. However, the therapeutic efficacy of ICBs is greatly compromised by immunosuppressive tumor microenvironments (TMEs) and low expression levels of programmed cell death ligand-1 (PD-L1). Herein, we constructed an amphiphilic prodrug by linking a hydrophobic STING agonist, MSA-2 and a hydrophilic chemotherapeutic drug, gemcitabine (GEM) via an ester bond, which can self-assemble into GEM-MSA-2 (G-M) nanoparticles (NPs) with a tumor growth inhibition (TGI) value of 87.1 % in a murine 4T1 transplantation tumor model. Notably, the immunogenic cell death (ICD)-triggering effect of GEM together with the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway activation properties of MSA-2 enables efficient infiltration of non-exhausting T cells and repolarization of macrophages from M2 to M1 types in the tumor microenvironment for transforming a cold tumor to a hot one. Most importantly, G-M NPs treatment increases the PD-L1 expression levels, thus providing a unique opportunity for further integration with anti-PD-L1 monoclonal antibody (αPD-L1) for eliciting stronger immunity that ultimately leads to a TGI value of 98.0 % in the primary tumor and significantly protects against distal and disseminated tumor rechallenge. Overall, this study presents a minimalist nano-prodrug combined with αPD-L1 as a simple yet robust translatable nanotechnology for potent chemo-immunotherapy of TNBC. STATEMENT OF SIGNIFICANCE: Enhancing the therapeutic efficacy of αPD-L1 for tumor immunotherapy via a translatable technology remains a challenge. We report herein facile integration of a binary nano-prodrug with αPD-L1 for potent immunotherapy of TNBC. An amphiphilic prodrug is constructed by linking a hydrophobic STING agonist, MSA-2 and a hydrophilic chemotherapeutic drug, gemcitabine (GEM) via an ester bond. The resulting self-assembled GEM-MSA-2 (G-M) nanoparticles (NPs) show a tumor growth inhibition (TGI) value of 87.1 % in a murine 4T1 transplantation tumor model. Besides the induced immunogenic cell death (ICD) and activated cGAS-STING pathway, G-M NPs increase the PD-L1 expression levels, providing a unique opportunity for further integration with αPD-L1 to elicit stronger immunity that ultimately leads to a TGI value of 98.0 % in the primary tumor and significantly protects against distal and disseminated tumor rechallenge.

STING in cancer immunoediting: Modeling tumor-immune dynamics throughout cancer development

Cancer immunoediting is a dynamic process of tumor-immune system interaction that plays a critical role in cancer development and progression. Recent studies have highlighted the importance of innate signaling pathways possessed by both cancer cells and immune cells in this process. The STING molecule, a pivotal innate immune signaling molecule, mediates DNA-triggered immune responses in both cancer cells and immune cells, modulating the anti-tumor immune response and shaping the efficacy of immunotherapy. Emerging evidence has shown that the activation of STING signaling has dual opposing effects in cancer progression, simultaneously provoking and restricting anti-tumor immunity, and participating in every phase of cancer immunoediting, including immune elimination, equilibrium, and escape. In this review, we elucidate the roles of STING in the process of cancer immunoediting and discuss the dichotomous effects of STING agonists in the cancer immunotherapy response or resistance. A profound understanding of the sophisticated roles of STING signaling pathway in cancer immunoediting would potentially inspire the development of novel cancer therapeutic approaches and overcome the undesirable protumor effects of STING activation.

Exploiting the gut microbiome for brain tumour treatment

Increasing evidence suggests that the gut microbiome plays a key role in a host of pathological conditions, including cancer. Indeed, the bidirectional communication that occurs between the gut and the brain, known as the 'gut-brain axis,' has recently been implicated in brain tumour pathology. Here, we focus on current research that supports a gut microbiome-brain tumour link with emphasis on high-grade gliomas, the most aggressive of all brain tumours, and the impact on the glioma tumour microenvironment. We discuss the potential use of gut-brain axis signals to improve responses to current and future therapeutic approaches. We highlight that the success of novel treatment strategies may rely on patient-specific microbiome profiles, and these should be considered for personalised treatment approaches.

The Skin Microbiome: A New Key Player in Melanoma, From Onset to Metastatic Stage

The skin microbiome plays a crucial role in maintaining skin health, defending the body against harmful pathogens, and interacting with melanoma. The composition of the skin microbiome can be affected by factors like age, gender, ethnicity, lifestyle, diet, and UV exposure. Certain bacteria like Staphylococcus and Veillonella are important for wound healing, while Cutibacterium acnes can play a role in dermatoses. UV radiation alters the skin microbiome, originates a "UV-resistome" and can lead to skin cancer initiation. Specifically, Staphylococcus epidermidis has shown protective effects against skin cancer, whereas Cutibacterium acnes can induce apoptosis in melanocytes postirradiation. The microbiome also interacts with melanoma treatment, affecting responses to immune checkpoint inhibitors. Strategies like bacteriotherapy, involving the manipulation of the gut microbiome but also the skin microbiome (with the gut-skin axis or through topical treatment) could improve treatment outcomes and show promise in melanoma therapy. Understanding the complex interplay between the skin microbiome, UV exposure, and melanoma development is crucial for developing personalized therapeutic approaches. Investigation into the skin microbiome and its potential role in melanoma progression continues to be an exciting area of research with implications for future therapeutic interventions.

Neutrophils in colorectal cancer: mechanisms, prognostic value, and therapeutic implications

Neutrophils, the most abundant myeloid cells in human peripheral blood, serve as the first defense line against infection and are also significantly involved in the initiation and progression of cancer. In colorectal cancer (CRC), neutrophils exhibit a dual function by promoting tumor events and exerting antitumor activity, which is related to the heterogeneity of neutrophils. The neutrophil extracellular traps (NETs), gut microbiota, and various cells within the tumor microenvironment (TME) are involved in shaping the heterogeneous function of neutrophils. This article provides an updated overview of the complex functions and underlying mechanisms of neutrophils in CRC and their pivotal role in guiding prognosis assessment and therapeutic strategies, aiming to offer novel insights into neutrophil-associated treatment approaches for CRC.

Integrated multiomics analysis highlights the immunosuppressive role of granulin precursor positive macrophages in hepatocellular carcinoma

It has been reported that tumor-associated macrophages (TAMs) play a complicated role in cancer occurrence and development, immune escape, and immune checkpoint blockade (ICB) resistance. However, the role of granulin precursor (GRN) highly expressed macrophages (hereafter refer to GRN+ macrophages) in hepatocellular carcinoma (HCC) remains poorly understood. Herein, we systematically integrated multiomics analysis of human tumor tissues to illustrate the functional role of GRN+ macrophages in HCC. GRN is selectively expressed by TAMs in different type of cancers including HCC, and was significantly associated with poor prognosis in several type of cancer. GRN was closely correlated with infiltration levels of most immune cells, especially the M2 macrophage cells in various cancers. In particular, both mRNA and protein expression level of GRN was significantly upregulated in HCC. Compared with tumor tissue, GRN was more significantly expressed in the stroma area between HCC tissues and adjacent non-tumor tissues. High expression of GRN was significantly correlated with M2-polarization of macrophages and T-cell exhaustion in HCC. GRN+ macrophages communicated with intratumoral immune cells, especially CD8+ T cells. Functionally, GRN+ macrophages contacted with CD8+ T cells, which inducing T-cell exhaustion. Our study offers a comprehensive understanding of the clinical relevance and immunological role of GRN+ macrophages in HCC, indicating its potential role as a promising target for immunotherapeutic strategies.

Tumor microbiome: roles in tumor initiation, progression, and therapy

Over the past few years, the tumor microbiome is increasingly recognized for its multifaceted involvement in cancer initiation, progression, and metastasis. With the application of 16S ribosomal ribonucleic acid (16S rRNA) sequencing, the intratumoral microbiome, also referred to as tumor-intrinsic or tumor-resident microbiome, has also been found to play a significant role in the tumor microenvironment (TME). Understanding their complex functions is critical for identifying new therapeutic avenues and improving treatment outcomes. This review first summarizes the origins and composition of these microbial communities, emphasizing their adapted diversity across a diverse range of tumor types and stages. Moreover, we outline the general mechanisms by which specific microbes induce tumor initiation, including the activation of carcinogenic pathways, deoxyribonucleic acid (DNA) damage, epigenetic modifications, and chronic inflammation. We further propose the tumor microbiome may evade immunity and promote angiogenesis to support tumor progression, while uncovering specific microbial influences on each step of the metastatic cascade, such as invasion, circulation, and seeding in secondary sites. Additionally, tumor microbiome is closely associated with drug resistance and influences therapeutic efficacy by modulating immune responses, drug metabolism, and apoptotic pathways. Furthermore, we explore innovative microbe-based therapeutic strategies, such as engineered bacteria, oncolytic virotherapy, and other modalities aimed at enhancing immunotherapeutic efficacy, paving the way for microbiome-centered cancer treatment frameworks.

The gut microbiome and cancer response to immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are widely used for cancer immunotherapy, yet only a fraction of patients respond. Remarkably, gut bacteria impact the efficacy of ICIs in fighting tumors outside of the gut. Certain strains of commensal gut bacteria promote antitumor responses to ICIs in a variety of preclinical mouse tumor models. Patients with cancer who respond to ICIs have a different microbiome compared with that of patients who don't respond. Fecal microbiota transplants (FMTs) from patients into mice phenocopy the patient tumor responses: FMTs from responders promote response to ICIs, whereas FMTs from nonresponders do not promote a response. In patients, FMTs from patients who have had a complete response to ICIs can overcome resistance in patients who progress on treatment. However, the responses to FMTs are variable. Though emerging studies indicate that gut bacteria can promote antitumor immunity in the absence of ICIs, this Review will focus on studies that demonstrate relationships between the gut microbiome and response to ICIs. We will explore studies investigating which bacteria promote response to ICIs in preclinical models, which bacteria are associated with response in patients with cancer receiving ICIs, the mechanisms by which gut bacteria promote antitumor immunity, and how microbiome-based therapies can be translated to the clinic.

Fungi, immunosenescence and cancer

Fungal microbes are a small but immunoreactive component of the human microbiome, which may influence cancer development, progression and therapeutic response. Immunosenescence is a process of immune dysfunction that occurs with aging, including lymphoid organ remodeling, contributing to alterations in the immune system in the elderly, which plays a critical role in many aspects of cancer. There is evidence for the interactions between fungi and immunosenescence in potentially regulating cancer progression and remodeling the tumor microenvironment (TME). In this review, we summarize potential roles of commensal and pathogenic fungi in modulating cancer-associated processes and provide more-detailed discussions on the mechanisms of which fungi affect tumor biology, including local and distant regulation of the TME, modulating antitumor immune responses and interactions with neighboring bacterial commensals. We also delineate the features of immunosenescence and its influence on cancer development and treatment, and highlight the interactions between fungi and immunosenescence in cancer. We discuss the prospects and challenges for harnessing fungi and immunosenescence in cancer diagnosis and/or treatment. Considering the limited understanding and techniques in conducting such research, we also provide our view on how to overcome challenges faced by the exploration of fungi, immunosenescence and their interactions on tumor biology.

Tumor Microenvironment Targeted by Polysaccharides in Cancer Prevention: Expanding Roles of Gut Microbiota and Metabolites

Since the development of immune checkpoint inhibitors (ICIs), immunotherapy has been widely used as a novel cancer treatment. However, the efficacy of tumor immunotherapy is largely dependent on the tumor microenvironment (TME). The high degree of heterogeneity within TME remains a major obstacle to acquire satisfactory therapeutic. Emerging studies suggest that gut microbiota is becoming an important regulator of TME. Polysaccharides as tumor immunotherapeutic agents or immune adjuvants not only exhibit antitumor activity by targeting gut microbiota, but also expand their role in the tumor immunotherapy by remodeling TME. To date, the mechanism by which polysaccharides targeting TME for tumor prevention via gut microbiota has not been deeply investigated. In this review, recent advances in the regulation of TME by polysaccharides through gut microbiota were systematically outlined, and the challenges and possible solutions in the clinical application of TME-targeted polysaccharides were discussed. Exploring the relationship between polysaccharides and TME from the perspective of gut microbiota may provide new ideas for the application of polysaccharides in tumor immunotherapy. This is a new area with major challenges that deserve further exploration.

The gut microbiome modulate response to immunotherapy in cancer

Gut microbiota have been reported to play an important role in the occurrence and development of malignant tumors. Currently, clinical studies have identified specific gut microbiota and its metabolites associated with efficacy of immunotherapy in multiple types of cancers. Preclinical investigations have elucidated that gut microbiota modulate the antitumor immunity and affect the efficacy of cancer immunotherapy. Certain microbiota and its metabolites may favorably remodel the tumor microenvironment by engaging innate and/or adaptive immune cells. Understanding how the gut microbiome interacts with cancer immunotherapy opens new avenues for improving treatment strategies. Fecal microbial transplants, probiotics, dietary interventions, and other strategies targeting the microbiota have shown promise in preclinical studies to enhance the immunotherapy. Ongoing clinical trials are evaluating these approaches. This review presents the recent advancements in understanding the dynamic interplay among the host immunity, the microbiome, and cancer immunotherapy, as well as strategies for modulating the microbiome, with a view to translating into clinical applications.

Investigating the role of intratumoral Streptococcus mitis in gastric cancer progression: insights into tumor microenvironment

Growing evidence implicates that intratumoral microbiota are closely linked to cancer progression; however, research on the role of these microbiota in the development of gastric cancer remains limited. Here, using 16 S rRNA sequencing, tumor tissue proteomics and serum cytokines analysis, we identified enrichment of specific microbial communities within tumors of gastric cancer patients, possibly affecting the tumor microenvironment by immune modulation, metabolic processes, and inflammatory responses. Based on the results of in vivo experiments and intratumoral microbiota analysis, we found that Streptococcus mitis can inhibit gastric cancer progression via suppressing M2 macrophage polarization and infiltration, as well as altering the intratumoral microbial community. In summary, our findings suggest that the intratumoral microbiota, exemplified by Streptococcus mites, may be involved in regulating the progression of gastric cancer, thereby emerging as potential therapeutic targets for this disease.

The STING antagonist SN-011 ameliorates cisplatin induced acute kidney injury via suppression of STING/NF-κB-mediated inflammation

Acute kidney injury (AKI) is a critical clinical syndrome associated with both innate and adaptive immune responses and thus increases mortality. Nevertheless, specific therapeutics for AKI are scarce so far. Recent studies have revealed that knockout of STING alleviate AKI, suggesting that STING could be an attractive target for AKI therapy. SN-011, a promising STING inhibitor, has not been reported in studies of its anti-AKI activity. In this study, we sought to examine the effects of SN-011 on AKI and explore its underlying mechanism. Our findings indicate that SN-011 could modulate the NF-κB and MAPK pathways, suppress the expression of inflammatory factors, and decrease ROS release in the cisplatin-induced cell model. In addition, SN-011 blocked the nuclear translocation of NF-κB p65, further mitigating the inflammatory response. In vivo, SN-011 enhanced survival rates and alleviated renal dysfunction. According to gene set enrichment analysis of sequencing data from mouse kidneys, we further confirm that SN-011 modulates the NF-κB and MAPK pathways. Our study suggests that SN-011 could be an attractive anti-inflammatory agent for further anti-AKI research.

Gut Microbiota-Tumor Microenvironment Interactions: Mechanisms and Clinical Implications for Immune Checkpoint Inhibitor Efficacy in Cancer

Cancer immunotherapy has transformed cancer treatment in recent years, with immune checkpoint inhibitors (ICIs) emerging as a key therapeutic approach. ICIs work by inhibiting the mechanisms that allow tumors to evade immune detection. Although ICIs have shown promising results, especially in solid tumors, patient responses vary widely due to multiple intrinsic and extrinsic factors within the tumor microenvironment. Emerging evidence suggests that the gut microbiota plays a pivotal role in modulating immune responses at the tumor site and may even influence treatment outcomes in cancer patients receiving ICIs. This review explores the complex interactions between the gut microbiota and the tumor microenvironment, examining how these interactions could impact the effectiveness of ICI therapy. Furthermore, we discuss how dysbiosis, an imbalance in gut microbiota composition, may contribute to resistance to ICIs, and highlight microbiota-targeted strategies to potentially overcome this challenge. Additionally, we review recent studies investigating the diagnostic potential of microbiota profiles in cancer patients, considering how microbial markers might aid in early detection and stratification of patient responses to ICIs. By integrating insights from recent preclinical and clinical studies, we aim to shed light on the potential of microbiome modulation as an adjunct to cancer immunotherapy and as a diagnostic tool, paving the way for personalized therapeutic approaches that optimize patient outcomes.

Dysbiosis-NK Cell Crosstalk in Pancreatic Cancer: Toward a Unified Biomarker Signature for Improved Clinical Outcomes

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor prognosis, primarily due to its immunosuppressive tumor microenvironment (TME), which contributes to treatment resistance. Recent research shows that the microbiome, including microbial communities in the oral cavity, gut, bile duct, and intratumoral environments, plays a key role in PDAC development, with microbial imbalances (dysbiosis) promoting inflammation, cancer progression, therapy resistance, and treatment side effects. Microbial metabolites can also affect immune cells, especially natural killer (NK) cells, which are vital for tumor surveillance, therapy response and treatment-related side effects. Dysbiosis can affect NK cell function, leading to resistance and side effects. We propose that a combined biomarker approach, integrating microbiome composition and NK cell profiles, can help predict treatment resistance and side effects, enabling more personalized therapies. This review examines how dysbiosis contributes to NK cell dysfunction in PDAC and discusses strategies (e.g., antibiotics, probiotics, vaccines) to modulate the microbiome and enhance NK cell function. Targeting dysbiosis could modulate NK cell activity, improve the effectiveness of PDAC treatments, and reduce side effects. However, further research is needed to develop unified NK cell-microbiome interaction-based biomarkers for more precise and effective patient outcomes.