The spleen contributes to the increase in PMN-MDSCs in orthotopic H22 hepatoma mice

CXCL5 impedes CD8+ T cell immunity by upregulating PD-L1 expression in lung cancer via PXN/AKT signaling phosphorylation and neutrophil chemotaxis

BACKGROUND

Lung cancer remains one of the most prevalent cancer types worldwide, with a high mortality rate. Upregulation of programmed cell death protein 1 (PD-1) and its ligand (PD-L1) may represent a key mechanism for evading immune surveillance. Immune checkpoint blockade (ICB) antibodies against PD-1 or PD-L1 are therefore widely used to treat patients with lung cancer. However, the mechanisms by which lung cancer and neutrophils in the microenvironment sustain PD-L1 expression and impart stronger inhibition of CD8+ T cell function remain unclear.

METHODS

We investigated the role and underlying mechanism by which PD-L1+ lung cancer and PD-L1+ neutrophils impede the function of CD8+ T cells through magnetic bead cell sorting, quantitative real-time polymerase chain reaction (RT-PCR), western blotting, enzyme-linked immunosorbent assays, confocal immunofluorescence, gene silencing, flow cytometry, etc. In vivo efficacy and safety studies were conducted using (Non-obeseDiabetes/severe combined immune deficiency) SCID/NOD mice. Additionally, we collected clinical and prognostic data from 208 patients who underwent curative lung cancer resection between 2017 and 2018.

RESULTS

We demonstrated that C-X-C motif chemokine ligand 5 (CXCL5) is markedly overexpressed in lung cancer cells and is positively correlated with a poor prognosis in patients with lung cancer. Mechanistically, CXCL5 activates the phosphorylation of the Paxillin/AKT signaling cascade, leading to upregulation of PD-L1 expression and the formation of a positive feedback loop. Moreover, CXCL5 attracts neutrophils, compromising CD8+ T cell-dependent antitumor immunity. These PD-L1+ neutrophils aggravate CD8+ T cell exhaustion following lung cancer domestication. Combined treatment with anti-CXCL5 and anti-PD-L1 antibodies significantly inhibits tumor growth in vivo.

CONCLUSIONS

Our findings collectively demonstrate that CXCL5 promotes immune escape through PD-L1 upregulation in lung cancer and neutrophils chemotaxis through autocrine and paracrine mechanisms. CXCL5 may serve as a potential therapeutic target in synergy with ICBs in lung cancer immunotherapy.

Cascade Co8FeS8@Co1-xS nano-enzymes trigger efficiently apoptosis-ferroptosis combination tumor therapy

This study involved the preparation of Metal Organic Frameworks (MOF)-derived Co8FeS8@Co1-xS nanoenzymes with strong interfacial interactions. The nanoenzymes presented the peroxidase (POD)-like activity and the oxidation activity of reduced glutathione (GSH). Accordingly, the dual activities of Co8FeS8@Co1-xS provided a self-cascading platform for producing significant amounts of hydroxyl radical (•OH) and depleting reduced glutathione, thereby inducing tumor cell apoptosis and ferroptosis. More importantly, the Co8FeS8@Co1-xS inhibited the anti-apoptosis protein B-cell lymphoma-2 (Bcl-2) and activated caspase family proteins, which caused tumor cell apoptosis. Simultaneously, Co8FeS8@Co1-xS affected the iron metabolism-related genes such as Heme oxygenase-1 (Hmox-1), amplifying the Fenton response and promoting apoptosis and ferroptosis. Therefore, the nanoenzyme synergistically killed anti-apoptotic tumor cells carrying Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. Furthermore, Co8FeS8@Co1-xS demonstrated good biocompatibility, which paved the way for constructing a synergistic catalytic nanoplatform for an efficient tumor treatment.

Splenectomy has opposite effects on the growth of primary compared with metastatic tumors in a murine colon cancer model

The spleen is a key source of circulating and tumor-infiltrating immune cells. However, the effect of splenectomy on tumor growth remains unclear. At 3 weeks after splenectomy, we subcutaneously injected LuM1 cells into BALB/c mice and evaluated the growth of primary tumors and lung metastases at 4 weeks after tumor inoculation. In addition, we examined the phenotypes of immune cells in peripheral blood by using flow cytometry and in tumor tissue by using multiplex immunohistochemistry. The growth of primary tumors was reduced in splenectomized mice compared with the sham-operated group. Conversely, splenectomized mice had more lung metastases. Splenectomized mice had fewer CD11b+cells, especially monocytic MDSCs (CD11b+Gr-1neg-lowLy6chigh), and NK cells (CD49b+CD335+). The proportion of NK cells was inversely correlated with the number of lung metastases. In splenectomized mice, the density of CD3+ and granzyme B+ CD8+ T cells was increased, with fewer M2-type macrophages in primary tumors, but NK cells were decreased markedly in lung. Splenectomy concurrently enhances T cell-mediated acquired immunity by reducing the number of monocytic MDSCs and suppresses innate immunity by decreasing the number of NK cells. Splenectomy has opposite effects on primary and metastatic lesions through differential regulation on these two immune systems.

Immune landscape and immunotherapy of hepatocellular carcinoma: focus on innate and adaptive immune cells

Hepatocellular carcinoma (HCC) is responsible for roughly 90% of all cases of primary liver cancer, and the cases are on the rise. The treatment of advanced HCC is a serious challenge. Immune checkpoint inhibitor (ICI) therapy has marked a watershed moment in the history of HCC systemic treatment. Atezolizumab in combination with bevacizumab has been approved as a first-line treatment for advanced HCC since 2020; however, the combination therapy is only effective in a limited percentage of patients. Considering that the tumor immune microenvironment (TIME) has a great impact on immunotherapies for HCC, an in-depth understanding of the immune landscape in tumors and the current immunotherapeutic approaches is extremely necessary. We elaborate on the features, functions, and cross talk of the innate and adaptive immune cells in HCC and highlight the benefits and drawbacks of various immunotherapies for advanced HCC, as well as future projections. HCC consists of a heterogeneous group of cancers with distinct etiologies and immune microenvironments. Almost all the components of innate and adaptive immune cells in HCC have altered, showing a decreasing trend in the number of tumor suppressor cells and an increasing trend in the pro-cancer cells, and there is also cross talk between various cell types. Various immunotherapies for HCC have also shown promising efficacy and application prospect. There are multilayered interwoven webs among various immune cell types in HCC, and emerging evidence demonstrates the promising prospect of immunotherapeutic approaches for HCC.

Detection of Antibodies against Endemic and SARS-CoV-2 Coronaviruses with Short Peptide Epitopes

(1) Background: Coronavirus proteins are quite conserved amongst endemic strains (eCoV) and SARS-CoV-2. We aimed to evaluate whether peptide epitopes might serve as useful diagnostic biomarkers to stratify previous infections and COVID-19. (2) Methods: Peptide epitopes were identified at an amino acid resolution that applied a novel statistical approach to generate data sets of potential antibody binding peptides. (3) Results: Data sets from more than 120 COVID-19 or eCoV-infected patients, as well as vaccinated persons, have been used to generate data sets that have been used to search in silico for potential epitopes in proteins of SARS-CoV-2 and eCoV. Peptide epitopes were validated with >300 serum samples in synthetic peptide micro arrays and epitopes specific for different viruses, in addition to the identified cross reactive epitopes. (4) Conclusions: Most patients develop antibodies against non-structural proteins, which are useful general markers for recent infections. However, there are differences in the epitope patterns of COVID-19, and eCoV, and the S-protein vaccine, which can only be explained by a high degree of cross-reactivity between the viruses, a pre-existing immune response against some epitopes, and even an alternate processing of the vaccine proteins.

Alteration of the tumor microenvironment by pharmacological inhibition of EZH2 in hepatocellular carcinoma

Enhancer of zeste homolog 2 (EZH2), a core component of polycomb repressive component 2 is overexpressed in a variety of cancers and recognized as a therapeutic target molecule. However, EZH2 possesses immunomodulatory functions in the tumor microenvironment (TME). The impact of EZH2 on TME of hepatocellular carcinoma (HCC) using immunocompetent mouse model was evaluated in the present study. UNC1999, an EZH2 inhibitor, impaired growth of the murine HCC cells (H22 cells) and induced apoptosis in a dose-dependent manner. Although UNC1999 significantly inhibited the growth of H22 cells-derived and Hepa1-6 cells-derived tumors in nonobese diabetic/severe combined immunodeficiency mice, its antitumor effect was diminished in allogenic BALB/c and C57BL/6 mice. Flow cytometric analyses of TME cells in BALB/c mice demonstrated a significant decrease in the number of interferon‑γ⁺ CD8⁺ T cells and regulatory T cells and a significant increase in the number of myeloid-derived suppressor cells (MDSCs). Administration of Gr-1 neutralizing antibody concomitant with UNC1999 restored antitumor effect accompanied by an increase in the number of CD8⁺ T cells followed by a decrease in the number of MDSCs. Chemokine antibody array demonstrated an enhanced expression of chemokines responsible for MDSCs recruitment such as C5a, CCL8, and CCL9. In conclusion, the study results demonstrated that EZH2 inhibitor contributed to attenuation of tumor immunity caused by TME arrangement. Combination therapy with EZH2 inhibitors and agents that reduce MDSCs might represent a novel therapeutic strategy for HCC.

Serum CXCL5 Detects Early Hepatocellular Carcinoma and Indicates Tumor Progression

Chemokines or chemotactic cytokines play a pivotal role in the immune pathogenesis of liver cirrhosis and hepatocellular carcinoma (HCC). Nevertheless, comprehensive cytokine profiling data across different etiologies of liver diseases are lacking. Chemokines might serve as diagnostic and prognostic biomarkers. In our study, we analyzed serum concentrations of 12 inflammation-related chemokines in a cohort of patients (n = 222) with cirrhosis of different etiologies and/or HCC. We compared 97 patients with cirrhosis and treatment-naïve HCC to the chemokine profile of 125 patients with cirrhosis but confirmed absence of HCC. Nine out of twelve chemokines were significantly elevated in sera of cirrhotic patients with HCC compared to HCC-free cirrhosis controls (CCL2, CCL11, CCL17, CCL20, CXCL1, CXCL5, CXCL9, CXCL10, CXCL11). Among those, CXCL5, CXCL9, CXCL10, and CXCL11 were significantly elevated in patients with early HCC according to the Barcelona Clinic Liver Cancer (BCLC) stages 0/A compared to cirrhotic controls without HCC. In patients with HCC, CXCL5 serum levels were associated with tumor progression, and levels of CCL20 and CXCL8 with macrovascular invasion. Importantly, our study identified CXCL5, CXCL9, and CXCL10 as universal HCC markers, independent from underlying etiology of cirrhosis. In conclusion, regardless of the underlying liver disease, patients with cirrhosis share an HCC-specific chemokine profile. CXCL5 may serve as a diagnostic biomarker in cirrhotic patients for early HCC detection as well as for tumor progression.

Tumor-Microenvironment Characterization of the MB49 Non-Muscle-Invasive Bladder-Cancer Orthotopic Model towards New Therapeutic Strategies

Bacillus Calmette-Guérin (BCG) instillations for the treatment of non-muscle-invasive bladder cancer patients can result in significant side effects and treatment failure. Immune checkpoint blockade and/or decreasing tumor-infiltrating myeloid suppressor cells may be alternative or complementary treatments. Here, we have characterized immune cell infiltration and chemoattractant molecules in mouse orthotopic MB49 bladder tumors. Our data show a 100-fold increase in CD45⁺ immune cells from day 5 to day 9 tumors including T cells and mainly myeloid cells. Both monocytic myeloid-derived suppressor-cells (M-MDSC) and polymorphonuclear (PMN)-MDSC were strongly increased in day 9 tumors, with PMN-MDSC representing ca. 70% of the myeloid cells in day 12 tumors, while tumor associated macrophages (TAM) were only modestly increased. The kinetic of PD-L1 tumor expression correlated with published data from patients with PD-L1 expressing bladder tumors and with efficacy of anti-PD-1 treatment, further validating the orthotopic MB49 bladder-tumor model as suitable for designing novel therapeutic strategies. Comparison of chemoattractants expression during MB49 bladder tumors grow highlighted CCL8 and CCL12 (CCR2-ligands), CCL9 and CCL6 (CCR-1-ligands), CXCL2 and CXCL5 (CXCR2-ligands), CXCL12 (CXCR4-ligand) and antagonist of C5/C5a as potential targets to decrease myeloid suppressive cells. Data obtained with a single CCR2 inhibitor however showed that the complex chemokine crosstalk would require targeting multiple chemokines for anti-tumor efficacy.

Antitumor and immunoregulatory activities of a novel polysaccharide from Astragalus membranaceus on S180 tumor-bearing mice

The Astragalus membranaceus polysaccharide (APS4) with direct cytotoxicity on various cancer cells has been prepared in our previous study, while the underlying therapeutic role of APS4 on solid tumors in vivo hasn't been investigated yet. Therefore, in this paper, the lymphocytes-mediated antitumor and immunoregulatory activities of APS4 were researched by establishing S180 tumor-bearing mice model. Flow cytometry analysis revealed that APS4 could effectively regulate the percentages of CD3⁺, CD4⁺, CD8⁺ T cells and CD19⁺ B cells in thymus, peripheral blood and spleen of S180 tumor-bearing mice, dose-dependently. H&E staining and cell cycle determination of solid tumors manifested that APS4 treatment could significantly inhibit the growth of solid tumors by inducing cells apoptosis. Furthermore, two-dimensional electrophoresis and western blot analysis further demonstrated that APS4 could activate antitumor-related immune cells and promote anaerobic metabolism of tumor microenvironment, thereby causing the apoptosis of S180 tumor cells. These data implicated that APS4 could be used as a potential dietary supplement for immune enhancement.

Therapeutic Values of Myeloid-Derived Suppressor Cells in Hepatocellular Carcinoma: Facts and Hopes

Simple Summary

Myeloid-derived suppressor cells restrict the effectiveness of immune-checkpoint inhibitors for a subset of patients mainly through thwarting T cell infiltration into tumor sites. Treatments targeting MDSCs have shown potent inhibitory effects on multiple tumors, including hepatocellular carcinoma. In this review, we summarize the pathological mechanisms of MDSCs and their clinical significance as prognostic and predictive biomarkers for HCC patients, and we provide the latest progress of MDSCs-targeting treatment in HCC.

Abstract

One of the major challenges in hepatocellular carcinoma (HCC) treatment is drug resistance and low responsiveness to systemic therapies, partly due to insufficient T cell infiltration. Myeloid-derived suppressor cells (MDSCs) are immature marrow-derived cell populations with heterogeneity and immunosuppression characteristics and are essential components of the suppressive tumor immune microenvironment (TIME). Increasing evidence has demonstrated that MDSCs are indispensable contributing factors to HCC development in a T cell-dependent or non-dependent manner. Clinically, the frequency of MDSCs is firmly linked to HCC clinical outcomes and the effectiveness of immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs). Furthermore, MDSCs can also be used as prognostic and predictive biomarkers for patients with HCC. Therefore, treatments reprograming MDSCs may offer potential therapeutic opportunities in HCC. Here, we recapitulated the dynamic relevance of MDSCs in the initiation and development of HCC and paid special attention to the effect of MDSCs on T cells infiltration in HCC. Finally, we pointed out the potential therapeutic effect of targeting MDSCs alone or in combination, hoping to provide new insights into HCC treatment.

Identification of seven novel ferroptosis-related long non-coding RNA signatures as a diagnostic biomarker for acute myeloid leukemia

Background

Ferroptosis is a newly discovered type of programmed cell death that participates in the biological processes of various cancers. However, the mechanism by which ferroptosis modulates acute myeloid leukemia (AML) remains unclear. This study aimed to investigate the role of ferroptosis-related long non-coding RNAs (lncRNAs) in AML and establish a corresponding prognostic model.

Methods

RNA-sequencing data and clinicopathological characteristics were obtained from The Cancer Genome Atlas database, and ferroptosis-related genes were obtained from the FerrDb database. The “limma” R package, Cox regression, and the least absolute shrinkage and selection operator were used to determine the ferroptosis-related lncRNA signature with the lowest Akaike information criteria (AIC). The risk score of ferroptosis-related lncRNAs was calculated and patients with AML were divided into high- and low-risk groups based on the median risk score. The Kaplan–Meier curve and Cox regression were used to evaluate the prognostic value of the risk score. Finally, gene set enrichment analysis (GSEA) and single-sample gene set enrichment analysis (ssGSEA) were performed to explore the biological functions of the ferroptosis-related lncRNAs.

Results

Seven ferroptosis-related lncRNA signatures were identified in the training group, and Kaplan–Meier and Cox regression analyses confirmed that risk scores were independent prognostic predictors of AML in both the training and validation groups (All P < 0.05). In addition, the area under the curve (AUC) analysis confirmed that the signatures had a good predictive ability for the prognosis of AML. GSEA and ssGSEA showed that the seven ferroptosis-related lncRNAs were related to glutathione metabolism and tumor immunity.

Conclusions

In this study, seven novel ferroptosis-related lncRNA signatures (AP001266.2, AC133961.1, AF064858.3, AC007383.2, AC008906.1, AC026771.1, and KIF26B-AS1) were established. These signatures were shown to accurately predict the prognosis of AML, which would provide new insights into strategies for the development of new AML therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01085-9.

Transferrin-Conjugated Erianin-Loaded Liposomes Suppress the Growth of Liver Cancer by Modulating Oxidative Stress

Background

Liver cancer is one of the most malignant human cancers, with few treatments and a poor prognosis. Erianin (ERN) is a natural compound with multiple pharmacological activities that has been reported to have numerous excellent effects against liver cancer in experimental systems. However, its application in vivo has been limited due to its poor aqueous solubility and numerous off-target effects. This study aimed to improve the therapeutic efficacy of ERN by developing novel ERN-loaded tumor-targeting nanoparticles.

Results

In this study, ERN was loaded into liposomes by ethanol injection (LP-ERN), and the resulting LP-ERN nanoparticles were treated with transferrin to form Tf-LP-ERN to improve the solubility and enhance the tumor-targeting of ERN. LP-ERN and Tf-LP-ERN nanoparticles had smooth surfaces and a uniform particle size, with particle diameters of 62.60 nm and 88.63 nm, respectively. In HepG2 and SMMC-7721 cells, Tf-LP-ERN induced apoptosis, decreased mitochondrial membrane potentials and increased ERN uptake more effectively than free ERN and LP-ERN. In xenotransplanted mice, Tf-LP-ERN inhibited tumor growth, but had a minimal effect on body weight and organ morphology. In addition, Tf-LP-ERN nanoparticles targeted tumors more effectively than free ERN and LP-ERN nanoparticles, and in tumor tissues Tf-LP-ERN nanoparticles promoted the cleavage PARP-1, caspase-3 and caspase-9, increased the expression levels of Bax, Bad, PUMA, and reduced the expression level of Bcl-2. Moreover, in the spleen of heterotopic tumor model BALB/c mice, ERN, LP-ERN and Tf-LP-ERN nanoparticles increased the expression levels of Nrf2, HO-1, SOD-1 and SOD-2, but reduced the expression levels of P-IKKα+β and P-NF-κB, with Tf-LP-ERN nanoparticles being most effective in this regard. Tf-LP-ERN nanoparticles also regulated the expression levels of TNF-α, IL-10 and CCL11 in serum.

Conclusion

Tf-LP-ERN nanoparticles exhibited excellent anti-liver cancer activity in vivo and in vitro by inducing cellular apoptosis, exhibiting immunoregulatory actions, and targeting tumor tissues, and did so more effectively than free ERN and LP-ERN nanoparticles. These results suggest that the clinical utility of a Tf-conjugated LP ERN-delivery system for the treatment of liver cancer warrants exploration.

Transferrin-Conjugated Erianin-Loaded Liposomes Suppress the Growth of Liver Cancer by Modulating Oxidative Stress

Background

Liver cancer is one of the most malignant human cancers, with few treatments and a poor prognosis. Erianin (ERN) is a natural compound with multiple pharmacological activities that has been reported to have numerous excellent effects against liver cancer in experimental systems. However, its application in vivo has been limited due to its poor aqueous solubility and numerous off-target effects. This study aimed to improve the therapeutic efficacy of ERN by developing novel ERN-loaded tumor-targeting nanoparticles.

Results

In this study, ERN was loaded into liposomes by ethanol injection (LP-ERN), and the resulting LP-ERN nanoparticles were treated with transferrin to form Tf-LP-ERN to improve the solubility and enhance the tumor-targeting of ERN. LP-ERN and Tf-LP-ERN nanoparticles had smooth surfaces and a uniform particle size, with particle diameters of 62.60 nm and 88.63 nm, respectively. In HepG2 and SMMC-7721 cells, Tf-LP-ERN induced apoptosis, decreased mitochondrial membrane potentials and increased ERN uptake more effectively than free ERN and LP-ERN. In xenotransplanted mice, Tf-LP-ERN inhibited tumor growth, but had a minimal effect on body weight and organ morphology. In addition, Tf-LP-ERN nanoparticles targeted tumors more effectively than free ERN and LP-ERN nanoparticles, and in tumor tissues Tf-LP-ERN nanoparticles promoted the cleavage PARP-1, caspase-3 and caspase-9, increased the expression levels of Bax, Bad, PUMA, and reduced the expression level of Bcl-2. Moreover, in the spleen of heterotopic tumor model BALB/c mice, ERN, LP-ERN and Tf-LP-ERN nanoparticles increased the expression levels of Nrf2, HO-1, SOD-1 and SOD-2, but reduced the expression levels of P-IKKα+β and P-NF-κB, with Tf-LP-ERN nanoparticles being most effective in this regard. Tf-LP-ERN nanoparticles also regulated the expression levels of TNF-α, IL-10 and CCL11 in serum.

Conclusion

Tf-LP-ERN nanoparticles exhibited excellent anti-liver cancer activity in vivo and in vitro by inducing cellular apoptosis, exhibiting immunoregulatory actions, and targeting tumor tissues, and did so more effectively than free ERN and LP-ERN nanoparticles. These results suggest that the clinical utility of a Tf-conjugated LP ERN-delivery system for the treatment of liver cancer warrants exploration.

Immunosuppressive Microenvironment Revealed by Immune Cell Landscape in Pre-metastatic Liver of Colorectal Cancer

Background: Colorectal cancer, the fourth leading cause of cancer mortality, is prone to metastasis, especially to the liver. The pre-metastatic microenvironment comprising various resident stromal cells and immune cells is essential for metastasis. However, how the dynamic evolution of immune components facilitates pre-metastatic niche formation remains unclear. Methods: Utilizing RNA-seq data from our orthotopic colorectal cancer mouse model, we applied single sample gene set enrichment analysis and Cell type Identification By Estimating Relative Subsets Of RNA Transcripts to investigate the tumor microenvironment landscape of pre-metastatic liver, and define the exact role of myeloid-derived suppressor cells (MDSCs) acting in the regulation of infiltrating immune cells and gene pathways activation. Flow cytometry analysis was conducted to quantify the MDSCs levels in human and mice samples. Results: In the current work, based on the high-throughput transcriptome data, we depicted the immune cell infiltration pattern of pre-metastatic liver and highlighted MDSCs as the dominant altered cell type. Notably, flow cytometry analysis showed that high frequencies of MDSCs, was detected in the pre-metastatic liver of orthotopic colorectal cancer tumor-bearing mice, and in the peripheral blood of patients with stage I-III colorectal cancer. MDSCs accumulation in the liver drove immunosuppressive factors secretion and immune checkpoint score upregulation, consequently shaping the pre-metastatic niche with sustained immune suppression. Metabolic reprogramming such as upregulated glycolysis/gluconeogenesis and HIF-1 signaling pathways in the primary tumor was also demonstrated to correlate with MDSCs infiltration in the pre-metastatic liver. Some chemokines were identified as a potential mechanism for MDSCs recruitment. Conclusion: Collectively, our study elucidates the alterations of MDSCs during pre-metastatic niche transformation, and illuminates the latent biological mechanism by which primary tumors impact MDSC aggregation in the targeted liver.

Atypical immunometabolism and metabolic reprogramming in liver cancer: Deciphering the role of gut microbiome

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related mortality worldwide. Much recent research has delved into understanding the underlying molecular mechanisms of HCC pathogenesis, which has revealed to be heterogenous and complex. Two major hallmarks of HCC include: (i) a hijacked immunometabolism and (ii) a reprogramming in metabolic processes. We posit that the gut microbiota is a third component in an entanglement triangle contributing to HCC progression. Besides metagenomic studies highlighting the diagnostic potential in the gut microbiota profile, recent research is pinpointing the gut microbiota as an instigator, not just a mere bystander, in HCC. In this chapter, we discuss mechanistic insights on atypical immunometabolism and metabolic reprogramming in HCC, including the examination of tumor-associated macrophages and neutrophils, tumor-infiltrating lymphocytes (e.g., T-cell exhaustion, regulatory T-cells, natural killer T-cells), the Warburg effect, rewiring of the tricarboxylic acid cycle, and glutamine addiction. We further discuss the potential involvement of the gut microbiota in these characteristics of hepatocarcinogenesis. An immediate highlight is that microbiota metabolites (e.g., short chain fatty acids, secondary bile acids) can impair anti-tumor responses, which aggravates HCC. Lastly, we describe the rising 'new era' of immunotherapies (e.g., immune checkpoint inhibitors, adoptive T-cell transfer) and discuss for the potential incorporation of gut microbiota targeted therapeutics (e.g., probiotics, fecal microbiota transplantation) to alleviate HCC. Altogether, this chapter invigorates for continuous research to decipher the role of gut microbiome in HCC from its influence on immunometabolism and metabolic reprogramming.