Bile acid synthesis impedes tumor-specific T cell responses during liver cancer

Microbiota-centered interventions to boost immune checkpoint blockade therapies

Immune checkpoint blockade therapies have markedly advanced cancer treatment by invigorating antitumor immunity and extending patient survival. However, therapeutic resistance and immune-related toxicities remain major concerns. Emerging evidence indicates that microbial dysbiosis diminishes therapeutic response rates, while a diverse gut ecology and key beneficial taxa correlate with improved treatment outcomes. Therefore, there is a growing understanding that manipulating the gut microbiota could boost therapy efficacy. This review examines burgeoning methods that target the gut microbiome to optimize therapy and innovative diagnostic tools to detect dysbiosis, and highlights challenges that remain to be addressed in the field.

A new incompatible combination: Reynoutria multiflora combined with Cullen corylifolium enhances idiosyncratic hepatotoxicity under immunological stress

ETHNOPHARMACOLOGICAL RELEVANCE

Compound preparations of traditional Chinese medicines (TCMs) have gained considerable interest. However, ensuring their safety is difficult because of ingredient complexity. Reynoutria multiflora (Thunb.) Moldenke (PM), commonly used in tonic preparations for clinical use, has been frequently reported to cause drug-induced liver injury (DILI). Liver injury caused by PM is idiosyncratic and its underlying mechanisms have been elucidated. However, a systematic evaluation of the safety of PM compound formulations is lacking. Our preliminary research predicted a potential compatibility risk between PM and Cullen corylifolium (Linnaeus) Medikus (PF); however, the specific effects and mechanisms of their combined action on the liver have not been fully studied.

AIM OF THE STUDY

To determine the effects of the PM and PF combination on the liver and its mechanisms.

MATERIALS AND METHODS

This study used a lipopolysaccharide-induced idiosyncratic (IDILI) model. Kits were employed to measure the liver function indices and ELISA was used to detect inflammatory factor content. The histopathological changes of the liver were observed using H&E and TUNEL staining. Serum metabolomics and liver transcriptomics were performed simultaneously to detect overall differences in metabolite and gene expression. Network pharmacology and molecular docking were used to screen hepatotoxic components and their potential pathways.

RESULTS

Liver function indicators and pathological results demonstrated that the combined treatment with PM and PF may exacerbate immune-mediated liver injury compared to treatment with either herb alone. Inflammatory factor levels indicated that the combination had an immuno-amplifying effect, further increasing inflammatory cytokine levels. Integrated metabolomic and transcriptomic analysis revealed that the combination primarily affected the primary bile acid synthesis and glycerophospholipid metabolism. This exacerbated hepatocyte apoptosis and liver injury by down-regulating the expression of key genes (BAAT and ALB) for bile acid metabolism. Network pharmacology and molecular docking identified 2,3,5,4'-Tetrahydroxy stilbene-2-Ο-β-D-glucoside and psoralidin as potential toxic components of PM and PF, respectively. These two ingredients specifically targeted the cytosolic DNA-sensing pathway and NOD-like receptor signalling pathway. When combined, PM and PF triggered immune hyperactivation via dual-pathway cross-regulation, leading to immuno-metabolic disorders, increased hepatocyte apoptosis and enhanced inflammatory cascade responses.

CONCLUSIONS

The PM and PF combination represents a newly identified incompatible pair that can aggravate IDILI under specific conditions. Our findings provide a critical reference for the safe use of compound medication, enriching the TCM combination theory.

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.

Unlocking mRNA Vaccine Potential in Liver Cancer Treatment via Synergistic Bile Acid Modulation

This Letter to the Editor explores synergistic mechanisms enhancing mRNA cancer vaccine efficacy through bile acid metabolism modulation in liver cancer treatment. The latest evidence indicates that bile acids significantly impair T cell function within the liver cancer microenvironment, creating an immunosuppressive milieu that hampers anti-tumor responses. Modulating bile acid composition, particularly increasing ursodeoxycholic acid (UDCA), could reshape the tumor microenvironment (TME) to favor mRNA vaccine-induced T cell activity-a promising strategy to overcome current immunotherapy limitations in liver cancer.

Microbiota-derived bile acids antagonize the host androgen receptor and drive anti-tumor immunity

Microbiota-derived bile acids (BAs) are associated with host biology/disease, yet their causal effects remain largely undefined. Herein, we speculate that characterizing previously undefined microbiota-derived BAs would uncover previously unknown BA-sensing receptors and their biological functions. We integrated BA metabolomics and microbial genetics to functionally profile >200 putative microbiota BA metabolic genes. We identified 56 less-characterized BAs, many of which are detected in humans/mammals. Notably, a subset of these BAs are potent antagonists of the human androgen receptor (hAR). They inhibit AR-related gene expression and are human-relevant. As a proof-of-principle, we demonstrate that one of these BAs suppresses tumor progression and potentiates the efficacy of anti-PD-1 treatment in an AR-dependent manner. Our findings show that an approach combining bioinformatics, BA metabolomics, and microbial genetics can expand our knowledge of the microbiota metabolic potential and reveal an unexpected microbiota BA-AR interaction and its role in regulating host biology.

BAAT away liver cancer: conjugated bile acids impair T cell function in hepatocellular carcinoma immunotherapy

In this renaissance era of gene therapy, a new study published by the Susan Kaech lab in Science demonstrates the use of CRISPR-Cas9 technology to selectively deplete conjugated bile acids in the liver by targeting the bile acid-CoA:amino acid N-acyltransferase (Baat) gene to improve responsiveness to immunotherapy. This study highlights the role of conjugated bile acids in impairing intratumoral T cell function by directly accumulating in resident liver T cells and driving mitochondrial dysfunction. Knockout of Baat reduced hepatic conjugated bile acid production, thus improving immunotherapy potency and reducing tumor burden. Subsequently, Baat liver knockout reduced levels of microbially produced secondary bile acids such as lithocholic acid, a known carcinogen and T cell toxin. This study mechanistically links bile acids to liver cancer immunotherapy success, setting the stage for bile acid-based screening approaches and pharmacologic manipulations for improved patient outcomes.

Impact of the ONCOBIOME network in cancer microbiome research

The European Union-sponsored ONCOBIOME network has spurred an international effort to identify and validate relevant gut microbiota-related biomarkers in oncology, generating a unique and publicly available microbiome resource. ONCOBIOME explores the effects of the microbiota on gut permeability and metabolism as well as on antimicrobial and antitumor immune responses. Methods for the diagnosis of gut dysbiosis have been developed based on oncomicrobiome signatures associated with the diagnosis, prognosis and treatment responses in patients with cancer. The mechanisms explaining how dysbiosis compromises natural or therapy-induced immunosurveillance have been explored. Through its integrative approach of leveraging multiple cohorts across populations, cancer types and stages, ONCOBIOME has laid the theoretical and practical foundations for the recognition of microbiota alterations as a hallmark of cancer. ONCOBIOME has launched microbiota-centered interventions and lobbies in favor of official guidelines for avoiding diet-induced or iatrogenic (for example, antibiotic- or proton pump inhibitor-induced) dysbiosis. Here, we review the key advances of the ONCOBIOME network and discuss the progress toward translating these into oncology clinical practice.

Exploring the role of gut microbiota in colorectal liver metastasis through the gut-liver axis

Colorectal liver metastasis (CRLM) represents a major therapeutic challenge in colorectal cancer (CRC), with complex interactions between the gut microbiota and the liver tumor microenvironment (TME) playing a crucial role in disease progression via the gut-liver axis. The gut barrier serves as a gatekeeper, regulating microbial translocation, which influences liver colonization and metastasis. Through the gut-liver axis, the microbiota actively shapes the TME, where specific microbial species and their metabolites exert dual roles in immune modulation. The immunologically "cold" nature of the liver, combined with the influence of the gut microbiota on liver immunity, complicates effective immunotherapy. However, microbiota-targeted interventions present promising strategies to enhance immunotherapy outcomes by modulating the gut-liver axis. Overall, this review highlights the emerging evidence on the role of the gut microbiota in CRLM and provides insights into the molecular mechanisms driving the dynamic interactions within the gut-liver axis.

Immo-bile-izing CD8+ T cell anti-tumor immunity

Hepatocellular carcinoma is poorly responsive to immune checkpoint blockade. In a recent issue of Science, Varanasi et al. reveal how bile acids dampen anti-tumor CD8+ T cell responses in the liver, contributing to cancer progression and poor immunotherapy outcomes.

Ena-bile-ing liver cancer growth

Bile acids differentially affect immune cell responses to liver cancer.