Melanoma and microbiota: Current understanding and future directions

Limosilactobacillus reuteri - a probiotic gut commensal with contextual impact on immunity

The gut microbiome plays a key role in human health, influencing various biological processes and disease outcomes. The historical roots of probiotics are traced back to Nobel Laureate Élie Metchnikoff, who linked the longevity of Bulgarian villagers to their consumption of sour milk fermented by Lactobacilli. His pioneering work led to the global recognition of probiotics as beneficial supplements, now a multibillion-dollar industry. Modern probiotics have been extensively studied for their immunomodulatory effects. Limosilactobacillus reuteri (L. reuteri), a widely used probiotic, has garnered significant attention for its systemic immune-regulatory properties, particularly in relation to autoimmunity and cancer. This review delves into the role of L. reuteri in modulating immune responses, with a focus on its impact on systemic diseases.

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.

Gut microbiota in melanoma: Effects and pathogeneses

The gut microbiota exhibits intricate connections with the body's immune system and holds significant implications for various diseases and cancers. Currently, accumulating evidence suggests a correlation between the composition of the gut microbiota and the development, treatment, and prognosis of melanoma. However, the underlying pathogenesis remains incompletely elucidated. In this comprehensive review, we present an in-depth review of the role played by gut microbiota in melanoma tumorigenesis, growth, metastasis, treatment response, and prognosis. Furthermore, we discuss the potential utility of gut microbiota as a promising prognostic marker. Lastly, we summarize three routes through which gut microbiota influences melanoma: immunity, aging, and the endocrine system. By modulating innate and adaptive immunity in patients with melanoma across different age groups and genders, the gut microbiota plays a crucial role in anti-tumor immune regulation from tumorigenesis to prognosis management, thereby impacting tumor growth and metastasis. This review also addresses current study limitations while highlighting future research prospects.

Intestinal Microbiome Modulation of Therapeutic Efficacy of Cancer Immunotherapy

Bacteria are associated with certain cancers and may induce genetic instability and cancer progression. The gut microbiome modulates the response to cancer therapy. Training machine learning models with response associated taxa or bacterial genes predict patients' response to immunotherapies with moderate accuracy. Clinical trials targeting the gut microbiome to improve immunotherapy efficacy have been conducted. While single bacterial strains or small consortia have not be reported yet to be successful, encouraging results have been reported in small single arm and randomized studies using transplant of fecal microbiome from cancer patients who successfully responded to therapy or from healthy volunteers.

Epigenetic mechanisms in melanoma development and progression

Knowledge of cancer development and progression gained over the last few decades has enabled mapping of genetic and epigenetic changes unique to different phases of tumor evolution. Here we focus on epigenetic changes that drive melanoma development and progression. We highlight the importance of epigenetic mechanisms which encompass crosstalk with melanoma microenvironment that affect metastasis and therapy resistance. This review summarizes recent advances and describes potential strategies to leverage this knowledge to devise new therapies.

Exosomes as key mediators in immune and cancer cell interactions: insights in melanoma progression and therapy

Exosomes (30-150 nm) are small extracellular vesicles that are secreted by cells into the extracellular environment and are known to mediate cell-to-cell communication. Exosomes contain proteins, lipids, and RNA molecules in relative abundance, capable of modifying the activity of target cells. Melanoma-derived exosomes (MEXs) promote the transfer of oncogenic signals and immunosuppressive factors into immune cells, resulting in a bias of the immune response towards tumor-promoting processes. MEXs could suppress the activation and proliferation of T cells and dendritic cells and induce differentiation of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). They can induce apoptosis of antigen-specific CD8 + T cells and promote the transfer of tumor antigens, resulting in immune evasion. Specifically, MEXs can shuttle cytokines like interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) to immune cells or express programmed death-ligand 1 (PD-L1 or CD274), creating an immune-suppressive microenvironment that promotes tumorigenesis. Since exosomes preferentially accumulate in melanoma tissues, this targeted delivery could enhance the bioavailability of treatments while limiting side effects. Here, we review the molecular composition of melanoma-derived exosomes, their mechanisms of action, and their potential as therapeutic targets or biomarkers in melanoma. The summarizations of these mechanisms to appropriately influence exosome-mediated interactions could yield new tactics to elicit anti-melanoma immunity or augment the therapeutic effects of current therapies.

Neoadjuvant cobimetinib and atezolizumab with or without vemurafenib for stage III melanoma: outcomes and the impact of the microbiome from the NeoACTIVATE trial

BACKGROUND

Neoadjuvant treatment has become standard for patients with high-risk operable stage III melanoma, but the optimal regimen is unknown. Targeted therapy approaches yield high pathological response rates, while immunotherapy regimens show favorable recurrence-free survival (RFS). NeoACTIVATE was designed to address whether a neoadjuvant combination of both targeted therapy and immunotherapy might leverage the benefits of each.

METHODS

We tested neoadjuvant treatment with 12 weeks of vemurafenib, cobimetinib, and atezolizumab for patients with BRAF-mutated (BRAFm) melanoma (cohort A) and cobimetinib and atezolizumab for patients with BRAF-wild-type (BRAFwt) melanoma (cohort B), regimens which we have shown generate a substantial major pathological response. After therapeutic lymph node dissection, patients received 24 weeks of adjuvant atezolizumab. Here, we report survival outcomes and their association with biomarkers assayed among the gut microbiome and peripheral blood immune subsets.

RESULTS

With 49 months median follow-up, the median RFS was not reached for cohort A and was 40.8 months for cohort B. At 24 months after operation, 2 of 14 cohort A patients and 4 of 13 cohort B patients had experienced distant relapse. Key findings from correlative analyses included diversity, taxonomic and functional metagenomic gut microbiome signals associated with distant metastasis-free survival at 2 years. Notably, we observed a strong correlation between low microbial arginine biosynthesis (required for T-cell activation and effector function) and early distant recurrence (p=0.0005), which correlated with taxonomic differential abundance findings. Peripheral blood immune monitoring revealed increased double-positive (CD4+CD8+) T cells in patients with early recurrence.

CONCLUSIONS

Neoadjuvant treatment with cobimetinib and atezolizumab±vemurafenib was associated with a low rate of distant metastasis in patients with high-risk stage III melanoma. Freedom from early distant metastasis was highly associated with taxonomic differences in gut microbiome structure and with functional pathway alterations known to modulate T cell immunity. Identification of predictive biomarkers will permit optimization of neoadjuvant therapy regimens for individual patients.

TRIAL REGISTRATION NUMBER

NCT03554083.

Gut microbiota affects PD-L1 therapy and its mechanism in melanoma

Immune checkpoint inhibitors (ICIs), particularly PD-1/PD-L1 blockade, have shown great success in treating melanoma. PD-L1 (B7-H1, CD274), a ligand of PD-1, binds to PD-1 on T cells, inhibiting their activation and proliferation through multiple pathways, thus dampening tumor-reactive T cell activity. Studies have linked PD-L1 expression in melanoma with tumor growth, invasion, and metastasis, making the PD-1/PD-L1 pathway a critical target in melanoma therapy. However, immune-related adverse events are common, reducing the effectiveness of anti-PD-L1 treatments. Recent evidence suggests that the gut microbiome significantly influences anti-tumor immunity, with the microbiome potentially reprogramming the tumor microenvironment and overcoming resistance to anti-PD-1 therapies in melanoma patients. This review explores the mechanisms of PD-1/PD-L1 in melanoma and examines how gut microbiota and its metabolites may help address resistance to anti-PD-1 therapy, offering new insights for improving melanoma treatment strategies.

Coupling culturomics and metagenomics sequencing to characterize the gut microbiome of patients with cancer treated with immune checkpoint inhibitors

BACKGROUND

The gut microbiome represents a novel biomarker for melanoma and non-small cell lung cancer (NSCLC) patients treated with immune checkpoint inhibitors (ICI). Gut microbiome metagenomics profiling studies of patients treated with immunotherapy identified bacteria associated with ICI efficacy, while others have been linked to resistance. However, limitations of metagenomics sequencing, such as complex bioinformatic processing requirements, necessity of a threshold for positive detection, and the inability to detect live organisms, have hindered our ability to fully characterize the gut microbiome. Therefore, combining metagenomics with high-throughput culture-based techniques (culturomics) represents an ideal strategy to fully characterize microbiome composition to more robustly position the microbiome as a biomarker of response to ICI.

METHODS

We performed culturomics using fecal samples from 22 patients from two academic centres in Canada and the United Kingdom with NSCLC and cutaneous melanoma treated with ICI (cancer group), comparing their microbiome composition to that of 7 healthy volunteers (HV), along with matching shotgun metagenomics sequencing.

RESULTS

For culturomics results, 221 distinct species were isolated. Among these 221 distinct species, 182 were identified in the cancer group and 110 in the HV group. In the HV group, the mean species richness was higher compared to the cancer group (34 vs. 18, respectively, p = 0.002). Beta diversity revealed separate clusters between groups (p = 0.004). Bifidobacterium spp. and Bacteroides spp. were enriched in HV, while cancer patients showed an overrepresentation of Enterocloster species, as well as Veillonella parvula. Next, comparing cancer patients' clinical outcomes to ICI, we observed that among the 20 most abundant bacteria present in non-responder patients, 2 belonged to the genus Enterocloster, along with an enrichment of Hungatella hathewayi and Cutibacterium acnes. In contrast, responders to ICI exhibited a predominance of Bacteroides spp. In NSCLC patients, metagenomics analysis revealed that of the 154 bacteria species isolated through culturomics, 61/154 (39%) were also identified by metagenomics sequencing. Importantly, 94 individual species were uniquely detected by culturomics.

CONCLUSION

These findings highlight that culturomics and metagenomics can serve as complementary tools to characterize the microbiome in patients with cancer. This integrated approach uncovers specific microbiome signatures that differentiate HV from cancer patients, and identifies specific species associated with therapy response and resistance.

Exosome-Based Vaccines: Pioneering New Frontiers in Combating Infectious Diseases and Cancer

Exosomes, small extracellular vesicles with lipid bilayer membranes, play a crucial role in cellular communication and can transfer diverse biological cargo, including proteins, lipids, and nucleic acids, from donor to recipient cells. Exosomes possess diverse immunological properties, such as antigen delivery and immune activation, along with excellent drug delivery capabilities, making them promising candidates for vaccine development. For different diseases, exosome-based vaccines can be designed as therapeutic or prophylactic vaccines by leveraging cellular immunity or humoral immunity. With the emergence of precision medicine, exosome-based personalized vaccines demonstrate exceptional therapeutic potential. This review systematically introduces the sources, biogenesis mechanisms, and components of exosomes and describes their regulatory roles in the immune system. Subsequently, the preparation, administration, and personalized therapy of exosome-based vaccines are discussed. Finally, the applications and clinical trials of exosome-based vaccines in the fields of anti-infection and anti-tumor therapies are particularly highlighted, with an analysis of the potential challenges in future vaccine development.

Molecular hydrogen as a potential mediator of the antitumor effect of inulin consumption

Inulin consumption and dihydrogen (H2) administration both exert antitumor effects on preclinical models as well as in clinical trials. As H2 is one of the major byproducts of inulin fermentation by bacterial species of the gut microbiota (GM), we hypothesized that H2 could mediate the antitumor effects of inulin. To provide evidence in favor of this hypothesis, we first determined the pattern of H2-exposure to which mice are subjected after inulin administration and developed an inhaled hydrogen therapy (H2T) protocol replicating this pattern. We then compared the effects on circulating immunity of a two-week daily inulin gavage with those of the corresponding H2T. We also compared the effects of inulin supplementation to those of the corresponding H2T on implanted melanoma growth and infiltration by T lymphocytes. Inulin and H2T induced a similar increase in circulating CD4+ and CD8+ T cells. In addition, both treatments similarly inhibited melanoma tumor growth. These results support a mechanism by which the H2 resulting from inulin fermentation by the GM diffuses across the intestinal barrier and stimulates the immunosurveillance responsible for the antitumor effect.

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.

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.

The role of the microbiome in skin cancer development and treatment

PURPOSE OF REVIEW

Recent research underscores the significant influence of the skin and gut microbiota on melanoma and nonmelanoma skin cancer (NMSC) development and treatment outcomes. This review aims to synthesize current findings on how microbiota modulates immune responses, particularly enhancing the efficacy of immunotherapies such as immune checkpoint inhibitors (ICIs).

RECENT FINDINGS

The microbiota's impact on skin cancer is multifaceted, involving immune modulation, inflammation, and metabolic interactions. Beneficial strains like Bifidobacterium and Lactobacillus have shown potential in supporting anti-PD-1 and anti-CTLA-4 therapies by promoting T-cell activation and immune surveillance. Evidence from preclinical and clinical studies, including fecal microbiota transplantation (FMT), highlights improved response rates in patients with microbiota-rich profiles. Notably, certain bacterial metabolites, such as inosine, contribute to enhanced antitumor activity by stimulating IFN-γ in CD8 + T cells.

SUMMARY

Understanding the interplay between microbiota and skin cancer treatment opens promising avenues for adjunctive therapies. Probiotic and prebiotic interventions, FMT, and microbiota modulation are emerging as complementary strategies to improve immunotherapy outcomes and address treatment resistance in melanoma and NMSC.

Leveraging Microorganisms to Combat Skin Cancer

Skin cancer, including melanoma and non-melanoma types, presents a significant and growing global health challenge due to its increasing incidence and mortality rates. While conventional treatments such as surgical excision, immunotherapy, and targeted therapies are well-established, microorganism-based approaches represent an innovative and promising alternative. These therapies employ live, genetically engineered, or commensal bacteria, viral vectors, or bacterial components to achieve various therapeutic mechanisms, including tumor targeting, immune system modulation, vascular disruption, competitive exclusion, drug delivery, and direct oncolysis. Despite their potential, these approaches require further investigation to address safety concerns, optimize treatment protocols, and gain a comprehensive understanding of their long-term outcomes.

Mannose Inhibits NSCLC Growth and Inflammatory Microenvironment by Regulating Gut Microbiota and Targeting OGT/hnRNP R/JUN/IL-8 Axis

Recent studies have reported direct antitumor effects of mannose, a natural six-carbon monosaccharide, in the treatment of cancer. Herein, we utilized cancer cell lines, animal models, organoids and experimental techniques such as multi-omics and cellular experiments to investigate the regulatory effects of mannose on NSCLC growth and the inflammatory microenvironment. We demonstrated that mannose can inhibit cancer cell growth, inflammatory cell infiltration and inflammatory cytokine expression in NSCLC tissue, and enhance the antitumor efficacy of immune checkpoint inhibitor both in vitro and in vivo. Orally administered mannose increased the proportion of probiotics in the gut microbiota, the abundance of anti-inflammatory and antitumor metabolites in the blood and feces of NSCLC-bearing mice. In NSCLC cells, mannose reduced JUN mRNA stability and subsequent IL-8 transcription of NSCLC cells by directly targeting OGT to suppress the O-GlcNAc glycosylation of hnRNP R, which bound and stabilized JUN mRNA in an O-GlcNAc glycosylation dependent manner. Taken together, our study demonstrated that mannose can suppress NSCLC by inhibiting tumor growth and the inflammatory microenvironment, and serve as a promising adjunct medication.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

MicroEpitope: an atlas of immune epitopes derived from cancer microbiomes

The majority of human cancers harbor molecular evidence of intratumoral microbiota. Microbiota-derived epitopes as molecular mimics of tumor antigens can bind human leukocyte antigen (HLA), thereby modulating host immunity. However, many questions remain regarding the mechanisms underlying the interactions between microbiota and the host's immune system in cancer. Here, MicroEpitope (http://bio-bigdata.hrbmu.edu.cn/MicroEpitope) was developed to provide and analyze the atlas of microbiota-derived epitopes in cancer. We manually collected available mass spectrometry (MS)-based HLA immunopeptidomes of 1190 samples across 24 cancer types. Alignment was performed against an in-house constructed theoretical library of human and intratumor microbiome encoded proteins, including 1298 bacterial and 124 viral species. Currently, MicroEpitope contains 51 497 bacteria and 767 virus-derived epitopes, mainly originating from Bacillus subtilis, Buchnera aphidicola and human cytomegalovirus. The common immunogenic features of epitopes were calculated, as well as their biochemical properties and the clinical relevance of corresponding bacteria and viruses across cancers. MicroEpitope also provides five analytical tools, and multiple visualization methods to facilitate understanding of the roles of microbiota-derived epitopes in cancer immunity. In summary, MicroEpitope represents a vital resource for investigating HLA-presented immunopeptidomes derived from cancer microbiomes, and could further enable rich insight in tumor antigen prioritization strategies.

Immune Signatures of Solid Tumor Patients Treated With Immune Checkpoint Inhibitors: An Observational Study

PURPOSE

Our study aimed to comprehensively describe the features of peripheral blood multiple immune cell phenotypes in solid tumor patients during pretreatment and after immunotherapy, providing a more convenient approach for studying the prognosis of immunotherapy in different solid tumor patients.

METHODS

We prospectively recruited patients with advanced solid tumors from Peking Union Medical College Hospital (PUMCH) between February 2023 and April 2024. Using multicolor flow cytometry, our study comprehensively observed and described the signatures of peripheral blood lymphocyte subsets including activation, proliferation, function, naïve memory, and T cell exhaustion immune cell subsets in this population of pretreatment and after immunotherapy.

RESULTS

Our study enrolled 59 advanced solid tumor patients with immunotherapy and 59 healthy controls were matched by age and gender. The results demonstrated a marked upregulation in the expression of lymphocyte activation markers CD38 and HLA-DR, as well as exhaustion and proliferation markers PD-1 and Ki67, in solid tumor patients compared to healthy controls. After immune checkpoint blockade (ICB) treatment, mainly the expression of Ki67CD4+T and HLA-DRCD38CD4+T, was significantly upregulated compared to pretreatment levels (p = 0.017, p = 0.019, respectively). We further found that gynecological tumors with better prognoses had higher baseline activation levels of CD4+ T cells compared to other solid tumors with poorer prognoses.

CONCLUSION

Our study elucidated the characteristics of different lymphocyte subsets in the peripheral blood of solid tumor patients. Further research revealed changes in the phenotypes of different lymphocyte subsets after ICIs treatment, with the activated phenotype of CD4+ T cells playing a crucial role in the antitumor effect. This lays the groundwork for further exploration of prognostic biomarkers and predictive models for cancer patients with immunotherapy.

Interplay of Transcriptomic Regulation, Microbiota, and Signaling Pathways in Lung and Gut Inflammation-Induced Tumorigenesis

Inflammation can positively and negatively affect tumorigenesis based on the duration, scope, and sequence of related events through the regulation of signaling pathways. A transcriptomic analysis of five pulmonary arterial hypertension, twelve Crohn's disease, and twelve ulcerative colitis high throughput sequencing datasets using R language specialized libraries and gene enrichment analyses identified a regulatory network in each inflammatory disease. IRF9 and LINC01089 in pulmonary arterial hypertension are related to the regulation of signaling pathways like MAPK, NOTCH, human papillomavirus, and hepatitis c infection. ZNF91 and TP53TG1 in Crohn's disease are related to the regulation of PPAR, MAPK, and metabolic signaling pathways. ZNF91, VDR, DLEU1, SATB2-AS1, and TP53TG1 in ulcerative colitis are related to the regulation of PPAR, AMPK, and metabolic signaling pathways. The activation of the transcriptomic network and signaling pathways might be related to the interaction of the characteristic microbiota of the inflammatory disease, with the lung and gut cell receptors present in membrane rafts and complexes. The transcriptomic analysis highlights the impact of several coding and non-coding RNAs, suggesting their relationship with the unlocking of cell phenotypic plasticity for the acquisition of the hallmarks of cancer during lung and gut cell adaptation to inflammatory phenotypes.

Manganese improves anti-PD-L1 immunotherapy via eliciting type I interferon signaling in melanoma

The immune checkpoint inhibitor therapy represented by blocking programmed cell death protein 1/ programmed cell death-ligand 1 (PD-1/PD-L1) has made significant progress in melanoma treatment. However, the response rate and therapeutic effect of immunotherapy alone are still not ideal for melanoma. In this study, we aimed to evaluate the defects of treating anti-PD-L1 alone and the therapeutic effect and molecular mechanism of combined therapy with anti-PD-L1 and MnCl2. We detected the changes of immune cell populations after anti-PD-L1 treatment in melanoma xenograft mouse model. Further, we evaluated the regulatory effect of MnCl2 on dendritic cells (DCs) maturation in vitro. Next, we tested the therapeutic effect and regulatory effect on the tumor microenvironment with anti-PD-L1 and MnCl2 via combining treatment with anti-PD-L1 and MnCl2. Anti-PD-L1 therapy has a certain tumor suppressive function, but the effect is not ideal. The results of flow cytometry showed that the number of CD4+ T cells and CD8+ T cells significantly increased after anti-PD-L1 treatment. However, the number of DCs remained basically unchanged after anti-PD-L1 treatment. In vitro, we confirmed that MnCl2 significantly promoted DCs maturation vis activating cGAS-STING signaling pathway. The combination of anti-PD-L1 and MnCl2 displayed the best tumor suppression effect in melanoma xenograft mouse model. In tumor microenvironment, the infiltration of T cells and the maturation of DCs were significantly promoted, demonstrating a strong anti-tumor immune response. In summary, we conclude that combining anti-PD-L1 with MnCl2 is a promising therapeutic strategy for melanoma.

The danger theory of immunity revisited

The danger theory of immunity, introduced by Polly Matzinger in 1994, posits that tissue stress, damage or infection has a decisive role in determining immune responses. Since then, a growing body of evidence has supported the idea that the capacity to elicit cognate immune responses (immunogenicity) relies on the combination of antigenicity (the ability to be recognized by T cell receptors or antibodies) and adjuvanticity (additional signals arising owing to tissue damage). Here, we discuss the molecular foundations of the danger theory while focusing on immunologically relevant damage-associated molecular patterns, microorganism-associated molecular patterns, and neuroendocrine stress-associated immunomodulatory molecules, as well as on their receptors. We critically evaluate patient-relevant evidence, examining how cancer cells and pathogenic viruses suppress damage-associated molecular patterns to evade immune recognition, how intestinal dysbiosis can reduce immunostimulatory microorganism-associated molecular patterns and compromise immune responses, and which hereditary immune defects support the validity of the danger theory. Furthermore, we incorporate the danger hypothesis into a close-to-fail-safe hierarchy of immunological tolerance mechanisms that also involve the clonal deletion and inactivation of immune cells.

A two-step, two-sample Mendelian randomization analysis investigating the interplay between gut microbiota, immune cells, and melanoma skin cancer

This study aims to rigorously explore the potential causal relationships among gut microbiota (GM), immune cells, and melanoma skin cancer among participants from Europe, where this disease exhibits significant prevalence and profound societal impact. Using the genome-wide association analysis database, a double-sample Mendelian randomization (MR) analysis was drawn upon to investigate GM, immune cells, and melanoma skin cancer. The inverse variance weighted approach was applied to estimate the causal connections among these variables. A two-step MR analysis was employed to quantitatively gauge the impact of immune cells mediated GM on melanoma skin cancer. To address potential sources of bias, such as pleiotropy and heterogeneity, multiple analytical techniques were integrated. The MR analysis pinpointed 6 GM taxa related to either an augmented or declined risk of late-stage melanoma skin cancer. In the same vein, 32 immune cell phenotypes were noticed as correlates with modified risk of melanoma skin cancer. Our study also implies that the probable association between GM and melanoma could be facilitated by 5 immune cell phenotypes. The findings of our study underline certain GM taxa and immune cells as potential influencers on the onset and development of melanoma skin cancer. Importantly, our results spotlight 5 immune cell phenotypes as potential agents mediating this association.

The DAV132 colon-targeted adsorbent does not interfere with plasma concentrations of antibiotics but prevents antibiotic-related dysbiosis: a randomized phase I trial in healthy volunteers

The deleterious impact of antibiotics (ATB) on the microbiome negatively influences immune checkpoint inhibitors (ICI) response in patients with cancer. We conducted a randomized phase I study (EudraCT:2019-A00240-57) with 148 healthy volunteers (HV) to test two doses of DAV132, a colon-targeted adsorbent, alongside intravenous ceftazidime-avibactam (CZA), piperacillin-tazobactam (PTZ) or ceftriaxone (CRO) and a group without ATB. The primary objective of the study was to assess the effect of DAV132 on ATB plasma concentrations and both doses of DAV132 did not alter ATB levels. Secondary objectives included safety, darkening of the feces, and fecal ATB concentrations. DAV132 was well tolerated, with no severe toxicity and similar darkening at both DAV132 doses. DAV132 led to significant decrease in CZA or PTZ feces concentration. When co-administered with CZA or PTZ, DAV132 preserved microbiome diversity, accelerated recovery to baseline composition and protected key commensals. Fecal microbiota transplantation (FMT) in preclinical cancer models in female mice from HV treated with CZA or PTZ alone inhibited anti-PD-1 response, while transplanted samples from HV treated with ATB + DAV132 circumvented resistance to anti-PD-1. This effect was linked to activated CD8+ T cell populations in the tumor microenvironment. DAV132 represents a promising strategy for overcoming ATB-related dysbiosis and further studies are warranted to evaluate its efficacy in cancer patients.

Gold nanostructures in melanoma: Advances in treatment, diagnosis, and theranostic applications

Melanoma, a lethal form of skin cancer, poses a significant challenge in oncology due to its aggressive nature and high mortality rates. Gold nanostructures, including gold nanoparticles (GNPs), offer myriad opportunities in melanoma therapy and imaging due to their facile synthesis and functionalization, robust stability, tunable physicochemical and optical properties, and biocompatibility. This review explores the emerging role of gold nanostructures and their composites in revolutionizing melanoma treatment paradigms, bridging the gap between nanotechnology and clinical oncology, and offering insights for researchers, clinicians, and stakeholders. It begins by elucidating the potential of nanotechnology-driven approaches in cancer therapy, highlighting the unique physicochemical properties and versatility of GNPs in biomedical applications. Various therapeutic modalities, including photothermal therapy, photodynamic therapy, targeted drug delivery, gene delivery, and nanovaccines, are discussed in detail, along with insights from ongoing clinical trials. In addition, the utility of GNPs in melanoma imaging and theranostics is explored, showcasing their potential in diagnosis, treatment monitoring, and personalized medicine. Furthermore, safety considerations and potential toxicities associated with GNPs are addressed, underscoring the importance of comprehensive risk assessment in clinical translation. Finally, the review concludes by discussing current challenges and future directions, emphasizing the need for innovative strategies to maximize the clinical impact of GNPs in melanoma therapy.

Dietary Commensal Wrestles Iron from Tumor Microenvironment to Activate Antitumoral Macrophages

The microbiome dictates the response to cancer immunotherapy efficacy. However, the mechanisms of how the microbiota impacts therapy efficacy remain poorly understood. In a recent issue of Nature Immunology, Sharma and colleagues elucidate a multifaceted, macrophage-driven mechanism exerted by a specific strain of fermented food commensal plantarum strain IMB19, LpIMB19. LpIMB19 activates tumor macrophages, resulting in the enhancement of cytotoxic cluster differentiation 8 (CD8) T cells. LpIMB19 administration led to an expansion of tumor-infiltrating CD8 T cells and improved the efficacy of anti-PD-L1 therapy. Rhamnose-rich heteropolysaccharide, a strain-specific cell wall component, was identified as the primary effector molecule of LplMB19. Toll-like receptor 2 signaling and the ability of macrophages to sequester iron were both critical for rhamnose-rich heteropolysaccharide-mediated macrophage activation upstream of the CD8 T-cell effector response and contributed to tumor cell apoptosis through iron deprivation. These findings reveal a well-defined mechanism connecting diet and health outcomes, suggesting that diet-derived commensals may warrant further investigation. Additionally, this work emphasizes the importance of strain-specific differences in studying microbiome-cancer interactions and the concept of "nutritional immunity" to enhance microbe-triggered antitumor immunity.

Bacteroidetes promotes esophageal squamous carcinoma invasion and metastasis through LPS-mediated TLR4/Myd88/NF-κB pathway and inflammatory changes

Gut microbiota plays a crucial role in gastrointestinal tumors. Additionally, gut microbes influence the progression of esophageal cancer. However, the major bacterial genera that affect the invasion and metastasis of esophageal cancer remain unknown, and the underlying mechanisms remain unclear. Here, we investigated the gut flora and metabolites of patients with esophageal squamous cell carcinoma and found abundant Bacteroides and increased secretion and entry of the surface antigen lipopolysaccharide (LPS) into the blood, causing inflammatory changes in the body. We confirmed these results in a mouse model of 4NQO-induced esophageal carcinoma in situ and further identified epithelial-mesenchymal transition (EMT) occurrence and TLR4/Myd88/NF-κB pathway activation in mouse esophageal tumors. Additionally, in vitro experiments revealed that LPS from Bacteroides fragile promoted esophageal cancer cell proliferation, migration, and invasion, and induced EMT by activating the TLR4/Myd88/NF-κB pathway. These results reveal that Bacteroides are closely associated with esophageal cancer progression through a higher inflammatory response level and signaling pathway activation that are both common to inflammation and tumors induced by LPS, providing a new biological target for esophageal cancer prevention or treatment.

Carbon Ion Irradiation Activates Anti-Cancer Immunity

Carbon ion beams have the unique property of higher linear energy transfer, which causes clustered damage of DNA, impacting the cell repair system. This sometimes triggers apoptosis and the release in the cytoplasm of damaged DNA, leading to type I interferon (IFN) secretion via the activation of the cyclic GMP-AMP synthase-stimulator of interferon genes pathway. Dendritic cells phagocytize dead cancer cells and damaged DNA derived from injured cancer cells, which together activate dendritic cells to present cancer-derived antigens to antigen-specific T cells in the lymph nodes. Thus, carbon ion radiation therapy (CIRT) activates anti-cancer immunity. However, cancer is protected by the tumor microenvironment (TME), which consists of pro-cancerous immune cells, such as regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. The TME is too robust to be destroyed by the CIRT-mediated anti-cancer immunity. Various modalities targeting regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages have been developed. Preclinical studies have shown that CIRT-mediated anti-cancer immunity exerts its effects in the presence of these modalities. In this review article, we provide an overview of CIRT-mediated anti-cancer immunity, with a particular focus on recently identified means of targeting the TME.

Current insights on gut microbiome and chronic urticaria: progress in the pathogenesis and opportunities for novel therapeutic approaches

Chronic urticaria (CU) is a prevalent skin disorder greatly impacting the patients' life quality, in which immune dysregulation mediated by gut microbiome plays a significant role. Several studies have found the gut dysbiosis exists in patients with CU. In addition, infection may also be one of the causes of CU. The primary treatment currently used for CU is the second-generation non-sedating H1-antihistamines (nsAH). However, there are some limitations in current therapies. Based on the latest evidence, this review provides an updated overview of how the gut dysbiosis influences CU development, explores potential therapeutic approaches based on the gut microbiota and summarizes the interaction between gut microbiota and current treatment.