Tumor-associated macrophages promoting PD-L1 expression in infiltrating B cells through the CXCL12/CXCR4 axis in human hepatocellular carcinoma.

The inflammation-related tumor microenvironment (TME) is one of the major driving forces of hepatocarcinogenesis. We aimed to investigate cell-to-cell communication among Hepatocellular Carcinoma (HCC) through re-analyzing HCC single-cell RNA-seq data, and to confirm such cellular interaction through in vitro and in vivo study. We found a subset of Regulatory B cells with PD-L1 expression (PD-L1+ Bregs), mainly located in adjacent HCC tissues. In co-localization with PD-L1+ Bregs, a subset of Tumor Associated Macrophages with high expression of CXCL12 (CXCL12+ TAMs) was also mainly located in adjacent HCC tissues. Moreover, CXCL12+ TAMs can be stimulated in vitro using an HCC conditional medium. Using CellChat analysis and Multiplex Immunohistochemistry staining (mIHC), CXCL12+ TAMs were found to be first recruited by Cancer-Associated Fibroblasts (CAFs) through a CD74/macrophage migration inhibitory factor (MIF) pattern, and further differentiated into TGF-ß-enriched tissues. Furthermore, CXCL12+ TAMs recruited PD-L1+ Bregs via the CXCL12/CXCR4 axis, and CXCR4 expression was significantly positively correlated to PD-L1 expression in PD-L1+ Bregs. At last, we confirmed the communications among CAFs, Macrophages and B cells and their tumor-promoting effects by using an orthotopic mouse model of HCC. Immunosuppressive HCC TME involving cell-to-cell communications comprised MIF-secreting CAFs, CXCL12-secreting TAMs, and PD-L1-producing Bregs, and their regulation could be promising therapeutic targets in future immunotherapy for human HCC.

Ileitis promotes MASLD progression via bile acid modulation and enhanced TGR5 signaling in ileal CD8+ T cells.

BACKGROUND & AIMS: Clinical evidence substantiates a link between inflammatory bowel disease, particularly Crohn's disease (CD), and metabolic dysfunction-associated steatotic liver disease (MASLD). This study aims to explore the underlying molecular mechanisms responsible for this association. METHODS: MASLD was induced by administering high-fat and western diets, while inflammatory bowel disease was induced using DSS (dextran sulfate sodium) and the Il10 knockout (KO) mouse model. The investigation into the role of secondary bile acids (SBAs) in ileitis involved employing metagenomic sequencing, conducting metabolomics detection, performing fecal microbiota transplantation, and constructing CD8+ T cell-specific gene knockout mice. RESULTS: In MASLD+DSS and Il10 KO MASLD mice, we observed ileitis characterized by T-cell infiltration and activation in the terminal ileum. This condition resulted in decreased bile acid levels in the portal vein and liver, inhibited hepatic farnesoid X receptor (FXR) activation, and exacerbated MASLD. Metagenomic and metabolomic analysis of ileal contents revealed increased Clostridium proliferation and elevated SBA levels in MASLD-associated ileitis. Experiments using germ-free mice and fecal microbiota transplantation suggested an association between SBA and MASLD-related ileitis. In vitro, SBAs promoted CD8+ T-cell activation via the TGR5, mTOR, and oxidative phosphorylation pathways. In vivo, TGR5 KO in CD8+ T cells effectively alleviated ileitis and reversed the MASLD phenotype. Clinical data further supported these findings, demonstrating a positive correlation between ileitis and MASLD. CONCLUSION: MASLD-induced changes in intestinal flora result in elevated levels of SBAs in the ileum. In the presence of a compromised intestinal barrier, this leads to severe CD8+ T cell-mediated ileitis through the TGR5/mTOR/oxidative phosphorylation signaling pathway. Ileitis-induced tissue damage impairs enterohepatic circulation, inhibits hepatic FXR activation, and exacerbates the MASLD phenotype. IMPACT AND IMPLICATIONS: Our study provides a comprehensive investigation of the interplay and underlying mechanisms connecting ileitis and metabolic dysfunction-associated steatotic liver disease (MASLD). Secondary bile acids produced by intestinal bacteria act as the critical link between MASLD and ileitis. Secondary bile acids exert their influence by disrupting liver lipid metabolism through the promotion of CD8+ T cell-mediated ileitis. In future endeavors to prevent and treat MASLD, it is essential to thoroughly account for the impact of the intestinal tract, especially the ileum, on liver function via the enterohepatic circulation.

The chronic consumption of dietary fructose promotes the gut Clostridium species imbalance and bile acid alterations in developing nonalcoholic fatty liver disease.

Excessive fructose intake is associated with the rising prevalence of nonalcoholic fatty liver disease (NAFLD). The gut microbiome (GM) and bile acids (BAs) are involved in the pathogenesis of NAFLD, but the impact of fructose on their cross-talk is unclear. In this study, adult male C57BL/6J mice were fed a normal diet with tap water (ND) or with 4% fructose in the drinking water (Fru), 60% high-fat diet with tap water (HF) or with 4% fructose solution (HFF) for 12 weeks. Targeted BA analysis was performed in five anatomical sites including the liver, ileum contents, portal serum, cecum contents, and feces. Metagenomic sequencing was performed to explore gut dysbiosis. Within 12 weeks, the 4% fructose diet could initially stimulate gut dysbiosis and BA upregulation in the ileum, portal serum, and cecum when the intestinal and hepatic transport system remained stable without hepatic lipid accumulation. However, the chronic consumption of fructose promoted HF-induced NAFLD, with significantly increased body weight, impaired glucose tolerance, and advanced liver steatosis. BA transporters were inhibited in HFF, causing the block of internal BA circulation and increased BA secretion via cecum contents and feces. Notably, lithocholic acid (LCA) and its taurine conjugates were elevated within the enterohepatic circulation. Meanwhile, the Clostridium species were significantly altered in both Fru and HFF groups and were closely associated with fructose and BA metabolism. In summary, excessive fructose caused gut dysbiosis and BA alterations, promoting HF-induced NAFLD. The crosstalk between Clostridium sp. and LCA species were potential targets in fructose-mediated NAFLD.

The XOR-IDH3α axis controls macrophage polarization in hepatocellular carcinoma.

BACKGROUND & AIMS: Tumor-associated macrophages (TAMs) are indispensable in the hepatocellular carcinoma (HCC) tumor microenvironment. Xanthine oxidoreductase (XOR), also known as xanthine dehydrogenase (XDH), participates in purine metabolism, uric acid production, and macrophage polarization to a pro-inflammatory phenotype. However, the role of XOR in HCC-associated TAMs is unclear. METHODS: We evaluated the XOR level in macrophages isolated from HCC tissues and paired adjacent tissues. We established diethylnitrosamine/carbon tetrachloride (CCl4)-induced and orthotopically implanted HCC mouse models using mice with Xdh-specific depletion in the myeloid cell lineage (Xdhf/fLyz2cre) or Kupffer cells (Xdhf/fClec4fcre). We determined metabolic differences using specific methodologies, including metabolomics and metabolic flux. RESULTS: We found that XOR expression was downregulated in HCC TAMs and positively correlated with patient survival, which was strongly related to the characteristics of the tumor microenvironment, especially hypoxia. Using HCC-inflicted mice (Xdhf/fLyz2cre and Xdhf/fClec4fcre), we revealed that XOR loss in monocyte-derived TAMs rather than Kupffer cells promoted their M2 polarization and CD8+ T-cell exhaustion, which exacerbated HCC progression. In addition, the tricarboxylic acid cycle was disturbed, and the generation of α-ketoglutarate was enhanced within XOR-depleted macrophages. XOR inhibited α-ketoglutarate production by interacting with IDH3α catalytic sites (K142 and Q139). The increased IDH3α activity caused increased adenosine and kynurenic acid production in TAMs, which enhanced the immunosuppressive effects of TAMs and CD8+ T cells. CONCLUSIONS: The XOR-IDH3α axis mediates TAM polarization and HCC progression and may be a small-molecule therapeutic or immunotherapeutic target against suppressive HCC TAMs. IMPACT AND IMPLICATIONS: Immunotherapies have been widely applied to the treatment of hepatocellular carcinoma (HCC), but to date they have been associated with unsatisfactory efficacy. The tumor microenvironment of HCC is full of different infiltrating immune cells. Tumor-associated macrophages (TAMs) are vital components in the tumor microenvironment and are involved in HCC progression. Herein, we confirm the downregulation of XOR expression in TAMs isolated from human HCC. The loss of XOR in monocyte-derived macrophages increases IDH3 activity and results in an increase in α-ketoglutarate production, which can promote M2-like polarization. Additionally, XOR-null TAMs derived from monocytes promote CD8+ T-cell exhaustion via the upregulation of immunosuppressive metabolites, including adenosine and kynurenic acid. Given the prevalence and high rate of incidence of HCC and the need for improved therapeutic options for patients, our findings identify potential therapeutic targets that may be further studied to develop improved therapies.

IFNγ Transcribed by IRF1 in CD4+ Effector Memory T Cells Promotes Senescence-Associated Pulmonary Fibrosis.

Physiologically aged lungs are prone to senescence-associated pulmonary diseases (SAPD). This study aimed to determine the mechanism and subtype of aged T cells affecting alveolar type II epithelial (AT2) cells, which promote the pathogenesis of senescence-associated pulmonary fibrosis (SAPF). Cell proportions, the relationship between SAPD and T cells, and the aging- and senescence-associated secretory phenotype (SASP) of T cells between young and aged mice were analyzed using lung single-cell transcriptomics. SAPD was monitored by markers of AT2 cells and found to be induced by T cells. Furthermore, IFNγ signaling pathways were activated and cell senescence, SASP, and T cell activation were shown in aged lungs. Physiological aging led to pulmonary dysfunction and TGF-ß1/IL-11/MEK/ERK (TIME) signaling-mediated SAPF, which was induced by senescence and SASP of aged T cells. Especially, IFNγ was produced by the accumulated CD4+ effector memory T (TEM) cells in the aged lung. This study also found that physiological aging increased pulmonary CD4+ TEM cells, IFNγ was produced mainly by CD4+ TEM cells, and pulmonary cells had increased responsiveness to IFNγ signaling. Specific regulon activity was increased in T cell subclusters. IFNγ transcriptionally regulated by IRF1 in CD4+ TEM cells promoted the epithelial-to-mesenchymal transition by activating TIME signaling and cell senescence of AT2 cells with aging. Accumulated IRF1+CD4+ TEM produced IFNγ in lung with aging and anti-IRF1 primary antibody treatment inhibited the expression of IFNγ. Aging might drive T cell differentiation toward helper T cells with developmental trajectories and enhance cell interactions of pulmonary T cells with other surrounding cells. Thus, IFNγ transcribed by IRF1 in CD4+ effector memory T cells promotes SAPF. IFNγ produced by CD4+ TEM cells in physiologically aged lungs could be a therapeutic target for preventing SAPF.

TOX deficiency facilitates the differentiation of IL-17A-producing γδ T cells to drive autoimmune hepatitis.

The specification of the αß/γδ lineage and the maturation of medullary thymic epithelial cells (mTECs) coordinate central tolerance to self-antigens. However, the mechanisms underlying this biological process remain poorly clarified. Here, we report that dual-stage loss of TOX in thymocytes hierarchically impaired mTEC maturation, promoted thymic IL-17A-producing γδ T-cell (Tγδ17) lineage commitment, and led to the development of fatal autoimmune hepatitis (AIH) via different mechanisms. Transfer of γδ T cells from TOX-deficient mice reproduced AIH. TOX interacted with and stabilized the TCF1 protein to maintain the balance of γδ T-cell development in thymic progenitors, and overexpression of TCF1 normalized αß/γδ lineage specification and activation. In addition, TOX expression was downregulated in γδ T cells from AIH patients and was inversely correlated with the AIH diagnostic score. Our findings suggest multifaceted roles of TOX in autoimmune control involving mTEC and Tγδ17 development and provide a potential diagnostic marker for AIH.

BCL-2 expression promotes immunosuppression in chronic lymphocytic leukemia by enhancing regulatory T cell differentiation and cytotoxic T cell exhaustion.

BACKGROUND: Chronic lymphocytic leukemia (CLL) results in increased susceptibility to infections. T cell dysfunction is not associated with CLL in all patients; therefore, it is important to identify CLL patients with T cell defects. The role of B-cell lymphoma-2 (BCL-2) in CLL has been explored; however, few studies have examined its role in T cells in CLL patients. Herein, we have investigated the regulatory role of BCL-2 in T cells in the CLL tumor microenvironment. METHODS: The expression of BCL-2 in T cells was evaluated using flow cytometry. The regulatory roles of BCL-2 were investigated using single-cell RNA sequencing (scRNA-seq) and verified using multi-parameter flow cytometry on CD4 and CD8 T cells. The clinical features of BCL-2 expression in T cells in CLL were also explored. RESULTS: We found a significant increase in BCL-2 expression in the T cells of CLL patients (n = 266). Single cell RNA sequencing (scRNA-seq) indicated that BCL-2+CD4+ T cells had the gene signature of increased regulatory T cells (Treg); BCL-2+CD8+ T cells showed the gene signature of exhausted cytotoxic T lymphocytes (CTL); and increased expression of BCL-2 was associated with T cell activation and cellular adhesion. The results from scRNA-seq were verified in peripheral T cells from 70 patients with CLL, wherein BCL-2+CD4+ T cells were enriched with Tregs and had higher expression of interleukin-10 and transforming growth factor-ß than BCL-2-CD4+ T cells. BCL-2 expression in CD8+T cells was associated with exhausted cells (PD-1+Tim-3+) and weak expression of granzyme B and perforin. T cell-associated cytokine profiling revealed a negative association between BCL-2+ T cells and T cell activation. Decreased frequencies and recovery functions of BCL-2+T cells were observed in CLL patients in complete remission after treatment with venetoclax. CONCLUSION: BCL-2 expression in the T cells of CLL patients is associated with immunosuppression via promotion of Treg abundance and CTL exhaustion.

Correction: The attenuated hepatocellular carcinoma-specific Listeria vaccine Lmdd-MPFG prevents tumor occurrence through immune regulation of dendritic cells.

[This corrects the article DOI: 10.18632/oncotarget.3558.].

Guanine Nucleotide-Binding Protein G(i) Subunit Alpha 2 Exacerbates NASH Progression by Regulating Peroxiredoxin 1-Related Inflammation and Lipophagy.

BACKGROUND AND AIMS: NASH is an advanced stage of liver disease accompanied by lipid accumulation, inflammation, and liver fibrosis. Guanine nucleotide-binding protein G(i) subunit alpha-2 (GNAI2) is a member of the "inhibitory" class of α-subunits, and recent studies showed that Gnai2 deficiency is known to cause reduced weight in mice. However, the role of GNAI2 in hepatocytes, particularly in the context of liver inflammation and lipid metabolism, remains to be elucidated. Herein, we aim to ascertain the function of GNAI2 in hepatocytes and its impact on the development of NASH. APPROACH AND RESULTS: Human liver tissues were obtained from NASH patients and healthy persons to evaluate the expression and clinical relevance of GNAI2. In addition, hepatocyte-specific Gnai2-deficient mice (Gnai2hep-/- ) were fed either a Western diet supplemented with fructose in drinking water (WDF) for 16 weeks or a methionine/choline-deficient diet (MCD) for 6 weeks to investigate the regulatory role and underlying mechanism of Gnai2 in NASH. GNAI2 was significantly up-regulated in liver tissues of patients with NASH. Following feeding with WDF or MCD diets, livers from Gnai2hep-/- mice had reduced steatohepatitis with suppression of markers of inflammation and an increase in lipophagy compared to Gnai2flox/flox mice. Toll-like receptor 4 signals through nuclear factor kappa B to trigger p65-dependent transcription of Gnai2. Intriguingly, immunoprecipitation, immunofluorescence, and mass spectrometry identified peroxiredoxin 1 (PRDX1) as a binding partner of GNAI2. Moreover, the function of PRDX1 in the suppression of TNF receptor-associated factor 6 ubiquitin-ligase activity and glycerophosphodiester phosphodiesterase domain-containing 5-related phosphatidylcholine metabolism was inhibited by GNAI2. Suppression of GNAI2 combined with overexpression of PRDX1 reversed the development of steatosis and fibrosis in vivo. CONCLUSIONS: GNAI2 is a major regulator that leads to the development of NASH. Thus, inhibition of GNAI2 could be an effective therapeutic target for the treatment of NASH.

Conjugated secondary 12α-hydroxylated bile acids promote liver fibrogenesis.

BACKGROUND: Significantly elevated serum and hepatic bile acid (BA) concentrations have been known to occur in patients with liver fibrosis. However, the roles of different BA species in liver fibrogenesis are not fully understood. METHODS: We quantitatively measured blood BA concentrations in nonalcoholic steatohepatitis (NASH) patients with liver fibrosis and healthy controls. We characterized BA composition in three mouse models induced by carbon tetrachloride (CCl4), streptozotocin-high fat diet (STZ-HFD), and long term HFD, respectively. The molecular mechanisms underlying the fibrosis-promoting effects of BAs were investigated in cell line models, a 3D co-culture system, and a Tgr5 (HSC-specific) KO mouse model. FINDINGS: We found that a group of conjugated 12α-hydroxylated (12α-OH) BAs, such as taurodeoxycholate (TDCA) and glycodeoxycholate (GDCA), significantly increased in NASH patients and liver fibrosis mouse models. 12α-OH BAs significantly increased HSC proliferation and protein expression of fibrosis-related markers. Administration of TDCA and GDCA directly activated HSCs and promoted liver fibrogenesis in mouse models. Blockade of BA binding to TGR5 or inhibition of ERK1/2 and p38 MAPK signaling both significantly attenuated the BA-induced fibrogenesis. Liver fibrosis was attenuated in mice with Tgr5 depletion. INTERPRETATION: Increased hepatic concentrations of conjugated 12α-OH BAs significantly contributed to liver fibrosis via TGR5 mediated p38MAPK and ERK1/2 signaling. Strategies to antagonize TGR5 or inhibit ERK1/2 and p38 MAPK signaling may effectively prevent or reverse liver fibrosis. FUNDINGS: This study was supported by the National Institutes of Health/National Cancer Institute Grant 1U01CA188387-01A1, the National Key Research and Development Program of China (2017YFC0906800); the State Key Program of National Natural Science Foundation (81430062); the National Natural Science Foundation of China (81974073, 81774196), China Postdoctoral Science Foundation funded project, China (2016T90381), and E-institutes of Shanghai Municipal Education Commission, China (E03008).

HIF-1α-induced expression of m6A reader YTHDF1 drives hypoxia-induced autophagy and malignancy of hepatocellular carcinoma by promoting ATG2A and ATG14 translation.

N6-methyladenosine (m6A), and its reader protein YTHDF1, play a pivotal role in human tumorigenesis by affecting nearly every stage of RNA metabolism. Autophagy activation is one of the ways by which cancer cells survive hypoxia. However, the possible involvement of m6A modification of mRNA in hypoxia-induced autophagy was unexplored in human hepatocellular carcinoma (HCC). In this study, specific variations in YTHDF1 expression were detected in YTHDF1-overexpressing, -knockout, and -knockdown HCC cells, HCC organoids, and HCC patient-derived xenograft (PDX) murine models. YTHDF1 expression and hypoxia-induced autophagy were significantly correlated in vitro; significant overexpression of YTHDF1 in HCC tissues was associated with poor prognosis. Multivariate cox regression analysis identified YTHDF1 expression as an independent prognostic factor in patients with HCC. Multiple HCC models confirmed that YTHDF1 deficiency inhibited HCC autophagy, growth, and metastasis. Luciferase reporter assays and chromatin immunoprecipitation demonstrated that HIF-1α regulated YTHDF1 transcription by directly binding to its promoter region under hypoxia. The results of methylated RNA immunoprecipitation sequencing, proteomics, and polysome profiling indicated that YTHDF1 contributed to the translation of autophagy-related genes ATG2A and ATG14 by binding to m6A-modified ATG2A and ATG14 mRNA, thus facilitating autophagy and autophagy-related malignancy of HCC. Taken together, HIF-1α-induced YTHDF1 expression was associated with hypoxia-induced autophagy and autophagy-related HCC progression via promoting translation of autophagy-related genes ATG2A and ATG14 in a m6A-dependent manner. Our findings suggest that YTHDF1 is a potential prognostic biomarker and therapeutic target for patients with HCC.

IL-22 Signaling in the Tumor Microenvironment.

Interleukin (IL)-22 belongs to the IL-10 cytokine family which performs biological functions by binding to heterodimer receptors comprising a type 1 receptor chain (R1) and a type 2 receptor chain (R2). IL-22 is mainly derived from CD4+ helper T cells, CD8+ cytotoxic T cells, innate lymphocytes, and natural killer T cells. It can activate downstream signaling pathways such as signal transducer and activator of transcription (STAT)1/3/5, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) through these heterodimer receptors. Although IL-22 is produced by immune cells, its specific receptor IL-22R1 is selectively expressed in nonimmune cells, such as hepatocytes, colonic epithelial cells, and pancreatic epithelial cells (Jiang et al. Hepatology 54(3):900-9, 2011; Jiang et al. BMC Cancer 13:59, 2013; Curd et al. Clin Exp Immunol 168(2):192-9, 2012). Immune cells do not respond to IL-22 stimulation directly within tumors, reports from different groups have revealed that IL-22 can indirectly regulate the tumor microenvironment (TME). In the present chapter, we discuss the roles of IL-22 in malignant cells and immunocytes within the TME, meanwhile, the potential roles of IL-22 as a target for drug discovery will be discussed.

RP11-323N12.5 promotes the malignancy and immunosuppression of human gastric cancer by increasing YAP1 transcription.

BACKGROUND: YAP1 is a core protein of the Hippo signaling pathway and is associated with malignancy and immunosuppression. In the present study, we discovered a novel lncRNA, RP11-323N12.5, with tumor promotion and immunosuppression activities through enhancing transcription of YAP1. METHODS: RP11-323N12.5 was identified using GEPIA. Its expression levels and their relationship with clinical features were investigated using clinical samples. The regulation of YAP1 transcription by RP11-323N12.5 was investigated in both GC and T cells, the tumor and immunosuppression promotion roles of RP11-323N12.5 were explored in vitro and in vivo. RESULTS: RP11-323N12.5 was the most up-regulated lncRNA in human GC, based on data from the TCGA database. Its transcription was significantly positively correlated with YAP1 transcription, YAP1 downstream gene expression which contribute to tumor growth and immunosuppression. RP11-323N12.5 promoted YAP1 transcription by binding to c-MYC in the YAP1 promoter region. Meanwhile, transcription of RP11-323N12.5 was also regulated by YAP1/TAZ/TEADs activation in GC cells. RP11-323N12.5 had tumor- and immnosuppression-promoting effects by enhancing YAP1 downstream genes in GC cells. Excessive RP11-323N12.5 was also observed in tumor-infiltrating leukocytes (TILs), which may be exosome-derived and also be related to enhanced Treg differentiation as a result YAP1 up-regulation. Moreover, RP11-323N12.5 promoted tumor growth and immunosuppression via YAP1 up-regulation in vivo. CONCLUSIONS: RP11-323N12.5 was the most up-regulated lncRNA in human GC and it promoted YAP1 transcription by binding to c-MYC within the YAP1 promoter in both GC and T cells. RP11-323N12.5 is an ideal therapeutic target in human GC due to its tumor-promoting and immunosuppression characteristics.

The mother relationship between insulin resistance and non-alcoholic steatohepatitis: Glucosinolates hydrolysis products as a promising insulin resistance-modulator and fatty liver-preventer.

Non-alcoholic fatty liver disease (NFLD) is one of the present public health problems which have no specific and effective treatment. The speed of the disease progression depends on the patient's lifestyle. Due to life stresses and lack of time, a high number of people depend on fast food containing a high amount of fats which one of the main causes of insulin resistance (IR). IR is one of the metabolic disorders which strongly intersected with molecular NAFLD and leading to its progression into non-alcoholic steatohepatitis (NASH). In this review, we introduced the updated statistics of NAFLD and NASH progression all over the world shows its importance, etiologies, and pathogenesis. Also, IR and its role in NASH initiation and progression explored, and current treatments with its limitations have been explained. Glucosinolates (GLS) is a group of phytochemicals which known by its potent hydrolysis products with promising anti-cancer effect. In this review, we have collected the recent experimental studies of different GLS hydrolysis products against IR and chronic liver diseases supported by our lab finding. Finally, we recommend this group of phytochemicals as promising molecules to be studied experimentally and clinically against a wide range of chronic liver diseases with an acceptable safety margin.

Hyocholic acid species improve glucose homeostasis through a distinct TGR5 and FXR signaling mechanism.

Hyocholic acid (HCA) and its derivatives are found in trace amounts in human blood but constitute approximately 76% of the bile acid (BA) pool in pigs, a species known for its exceptional resistance to type 2 diabetes. Here, we show that BA depletion in pigs suppressed secretion of glucagon-like peptide-1 (GLP-1) and increased blood glucose levels. HCA administration in diabetic mouse models improved serum fasting GLP-1 secretion and glucose homeostasis to a greater extent than tauroursodeoxycholic acid. HCA upregulated GLP-1 production and secretion in enteroendocrine cells via simultaneously activating G-protein-coupled BA receptor, TGR5, and inhibiting farnesoid X receptor (FXR), a unique mechanism that is not found in other BA species. We verified the findings in TGR5 knockout, intestinal FXR activation, and GLP-1 receptor inhibition mouse models. Finally, we confirmed in a clinical cohort, that lower serum concentrations of HCA species were associated with diabetes and closely related to glycemic markers.

Resistance to FGFR1-targeted therapy leads to autophagy via TAK1/AMPK activation in gastric cancer.

BACKGROUND: Fibroblast growth factor receptor 1 (FGFR1) is frequently dysregulated in various tumors. FGFR inhibitors have shown promising therapeutic value in several preclinical models. However, tumors resistant to FGFR inhibitors have emerged, compromising therapeutic outcomes by demonstrating markedly aggressive metastatic progression; however, the underlying signaling mechanism of resistance remains unknown. METHODS: We established FGFR inhibitor-resistant cell models using two gastric cancer (GC) cell lines, MGC-803 and BGC-823. RNA-seq was performed to determine the continuous cellular transcriptome changes between parental and resistant cells. We explored the mechanism of resistance to FGFR inhibitor, using a subcutaneous tumor model and GC patient-derived tumor organotypic culture. RESULTS: We observed that FGFR1 was highly expressed in GC and FGFR1 inhibitor-resistant cell lines, demonstrating elevated levels of autophagic activity. These resistant cells were characterized by epithelial-mesenchymal transition (EMT) required to facilitate metastatic outgrowth. In drug-resistant cells, the FGFR1 inhibitor regulated GC cell autophagy via AMPK/mTOR signal activation, which could be blocked using either pharmacological inhibitors or essential gene knockdown. Furthermore, TGF-ß-activated kinase 1 (TAK1) amplification and metabolic restrictions led to AMPK pathway activation and autophagy. In vitro and in vivo results demonstrated that the FGFR inhibitor AZD4547 and TAK1 inhibitor NG25 synergistically inhibited proliferation and autophagy in AZD4547-resistant cell lines and patient-derived GC organotypic cultures. CONCLUSIONS: We elucidated the molecular mechanisms underlying primary resistance to FGFR1 inhibitors in GC, and revealed that the inhibition of FGFR1 and TAK1 signaling could present a potential novel therapeutic strategy for FGFR1 inhibitor-resistant GC patients.

IL-6 promotes PD-L1 expression in monocytes and macrophages by decreasing protein tyrosine phosphatase receptor type O expression in human hepatocellular carcinoma.

BACKGROUND: We have previously discovered a relationship between the low expression of protein tyrosine phosphatase, receptor type O (PTPRO) in tumor-infiltrating T cells and immunosuppression. The aim of the present study was to investigate the relationship between decreased PTPRO and increased programmed death ligand 1 (PD-L1) in both the peripheral monocytes and tumor-infiltrating macrophages of human hepatocellular carcinoma (HCC). METHODS: The expression and correlation of all the indices were explored in monocytes and tumor-infiltrating macrophages within both human and mice HCC. The mechanic regulations were studied by using both in vitro and in vivo studies. RESULTS: We found a significant decrease in PTPRO in HCC peripheral monocytes that was associated with increased PD-L1 expression in peripheral monocytes and tumor-associated macrophages (TAMs) in HCC. Monocyte PD-L1 and PTPRO therefore could serve as valuable prognostic indicators for post-surgery patients with HCC and were associated with increased T-cell exhaustion (Tim3+T cells). A depletion of PTPRO promoted PD-L1 secretion in both monocytes and macrophages through the JAK2/STAT1 and JAK2/STAT3/c-MYC pathways. Increased IL-6 expression was associated with activation of JAK2/STAT3/c-MYC and with decreased PTPRO expression through the STAT3/c-MYC/miR-25-3 p axis. Monocytes and TAMs showed significantly increased miR-25-3 p expression, which could target the 3' untranslated region of PTPRO. The miR-25-3 p expression positively correlated with serum IL-6 levels, but inversely correlated with PTPRO in HCC monocytes. IL-6/STAT3/c-MYC activation enhanced in vitro miR-25-3 p transcription and decreased PTPRO, while further promoting PD-L1 secretion. Adoptive cell transfer of c-MYC/miR-25-3 p-modified monocytes promoted tumor growth by downregulating PTPRO and causing a PD-L1-induced immunosuppression in an orthotopic tumor transplantation model. CONCLUSIONS: Increased serum IL-6 downregulated PTPRO expression in HCC monocytes and macrophages by activating STAT3/c-MYC/miR-25-3 p and by further enhancing PD-L1 expression through JAK2/STAT1 and JAK2/STAT3/c-MYC signaling.

Listeria-based hepatocellular carcinoma vaccine facilitates anti-PD-1 therapy by regulating macrophage polarization.

Recently, patients with advanced cancers have been benefited greatly from immune checkpoint blockade immunotherapy. However, immune checkpoint blockade is still suboptimal in HCC treatment and more immune modifications are needed to achieve an efficient therapeutic goal. Here, we investigated the combined administration of a Listeria-based HCC vaccine, Lmdd-MPFG, and the anti-PD-1 immune checkpoint blockade antibody. We found that Lmdd-MPFG promoted the expression of PD-L1 in HCC cells but resensitized the tumor local T cell to respond to the anti-PD-1 immunotherapy. Mechanistically, the Lmdd-MPFG vaccine activates the NF-κB pathway in the tumor-associated macrophages (TAMs) through the TLR2 and MyD88 pathway, and recruits p62 to activate the autophagy pathway. The overall effect is skewing the TAMs from M2-polarized TAMs into the M1-polarized TAMs. Most importantly, it skewed the cytokine profiles into antitumor one in the tumor microenvironment (TME). This change restores the T-cell reactivity to the anti-PD-1 blockade. Our results suggested that Lmdd-MPFG combined with PD-1 blockade exerted synergistic antitumor effects through modifying TAMs in the TME and removing T-cell inhibitory signals, thereby providing a new potential strategy for HCC treatment.