TLR2 limits development of hepatocellular carcinoma by reducing IL18-mediated immunosuppression

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Novel therapeutic strategies targeting myeloid-derived suppressor cell immunosuppressive mechanisms for cancer treatment

Cancer is the leading cause of death globally superseded only by cardiovascular diseases, and novel strategies to overcome therapeutic resistance against existing cancer treatments are urgently required. Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells with potent immunosuppressive capacity against well-established anti-tumour effectors such as natural killer cells (NK cells) and T cells thereby promoting cancer initiation and progression. Critically, MDSCs are readily identified in almost all tumour types and human cancer patients, and numerous studies in the past decade have recognised their role in contributing to therapeutic resistance against all four pillars of modern cancer treatment, namely surgery, chemotherapy, radiotherapy and immunotherapy. MDSCs suppress anti-tumour immunity through a plethora of mechanisms including the well-characterised arginase 1 (Arg1), inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS)-mediated pathways, along with several other more recently discovered. MDSCs are largely absent in healthy homeostatic states and predominantly exist in pathological conditions, making them attractive therapeutic targets. However, the lack of specific markers identified for MDSCs to date greatly hindered therapeutic development, and currently there are no clinically approved drugs that specifically target MDSCs. Methods to deplete MDSCs clinically and inhibit their immunosuppressive function will be crucial in advancing cancer treatment and to overcome treatment resistance. This review provides a detailed overview of the current understandings behind the mechanisms of MDSC-mediated suppression of anti-tumour immunity, and discusses potential strategies to target MDSC immunosuppressive mechanisms to overcome therapeutic resistance.

Hepatocellular Carcinoma: Old and Emerging Therapeutic Targets

Liver cancer, predominantly hepatocellular carcinoma (HCC), globally ranks sixth in incidence and third in cancer-related deaths. HCC risk factors include non-viral hepatitis, alcohol abuse, environmental exposures, and genetic factors. No specific genetic alterations are unequivocally linked to HCC tumorigenesis. Current standard therapies include surgical options, systemic chemotherapy, and kinase inhibitors, like sorafenib and regorafenib. Immunotherapy, targeting immune checkpoints, represents a promising avenue. FDA-approved checkpoint inhibitors, such as atezolizumab and pembrolizumab, show efficacy, and combination therapies enhance clinical responses. Despite this, the treatment of hepatocellular carcinoma (HCC) remains a challenge, as the complex tumor ecosystem and the immunosuppressive microenvironment associated with it hamper the efficacy of the available therapeutic approaches. This review explores current and advanced approaches to treat HCC, considering both known and new potential targets, especially derived from proteomic analysis, which is today considered as the most promising approach. Exploring novel strategies, this review discusses antibody drug conjugates (ADCs), chimeric antigen receptor T-cell therapy (CAR-T), and engineered antibodies. It then reports a systematic analysis of the main ligand/receptor pairs and molecular pathways reported to be overexpressed in tumor cells, highlighting their potential and limitations. Finally, it discusses TGFβ, one of the most promising targets of the HCC microenvironment.

MicroRNA-143 as a potential tumor suppressor in cancer: An insight into molecular targets and signaling pathways

MicroRNAs (MiRNAs), which are highly conserved and small noncoding RNAs, negatively regulate gene expression and influence signaling pathways involved in essential biological activities, including cell proliferation, differentiation, apoptosis, and cell invasion. MiRNAs have received much attention in the past decade due to their significant roles in cancer development. In particular, microRNA-143 (miR-143) is recognized as a tumor suppressor and is downregulated in most cancers. However, it seems that miR-143 is upregulated in rare cases, such as prostate cancer stem cells, and acts as an oncogene. The present review will outline the current studies illustrating the impact of miR-143 expression levels on cancer progression and discuss its target genes and their relevant signaling pathways to discover a potential therapeutic way for cancer.

Dihydroartemisinin inhibited interleukin-18 expression by decreasing YAP1 in hepatocellular carcinoma cells

BACKGROUND

Yes-associated protein 1 (YAP1) is highly expressed in liver cancer and has been used as an independent prognostic marker for hepatocellular carcinoma (HCC), while inhibition of YAP1 slows down the progression of HCC. Interleukin-18 (IL-18) also tends to be highly expressed in liver cancer. Previous research has proved that dihydroartemisinin (DHA) plays an important role in HCC treatment by reducing YAP1 expression. However, the relationship between YAP1 and IL-18 has not been reported in HCC, especially during DHA therapy.

OBJECTIVE

The purpose of this study was to clarify the relationship between YAP1 and IL-18 in HCC cells, and to explicit the role of IL-18 in the treatment of HCC by DHA.

METHODS AND RESULTS

We found that YAP1 and IL-18 were highly expressed in patients with hepatocellular carcinoma by bioinformatics analysis. Moreover, YAP1 was positively correlated with IL18 in liver cancer. YAP1 and IL18 correlated with immune cell infiltration, notably T cell exhaustion. YAP1 knockdown decreased IL-18 expression, while YAP1 overexpression increased the IL-18 expression in HCC cells. DHA reduced IL-18 expression through YAP1 in HCC cells. Further, DHA reduced the growth of Hepa1-6 cells subcutaneous xenograft tumors by inhibiting the expression of YAP1 and IL-18. However, DHA improved IL-18 in serum and adjacent tissues from DEN/TCPOBOP-induced liver tumor model in C57BL/6 mice.

CONCLUSION

YAP1 was positively correlated with IL-18 in HCC. DHA reduced the expression of IL-18 by inhibiting YAP1 and plays a role in the treatment of HCC. Our study suggested that IL-18 is a potential target for the treatment of HCC, and DHA is a promising drug for HCC therapy.

DATA AVAILABILITY

The dataset that supports the findings of this study is available from the corresponding author upon reasonable request.

Toll-like receptor-targeted anti-tumor therapies: Advances and challenges

Toll-like receptors (TLRs) are pattern recognition receptors, originally discovered to stimulate innate immune reactions against microbial infection. TLRs also play essential roles in bridging the innate and adaptive immune system, playing multiple roles in inflammation, autoimmune diseases, and cancer. Thanks to the immune stimulatory potential of TLRs, TLR-targeted strategies in cancer treatment have proved to be able to regulate the tumor microenvironment towards tumoricidal phenotypes. Quantities of pre-clinical studies and clinical trials using TLR-targeted strategies in treating cancer have been initiated, with some drugs already becoming part of standard care. Here we review the structure, ligand, signaling pathways, and expression of TLRs; we then provide an overview of the pre-clinical studies and an updated clinical trial watch targeting each TLR in cancer treatment; and finally, we discuss the challenges and prospects of TLR-targeted therapy.

TLR2 agonist promotes myeloid-derived suppressor cell polarization via Runx1 in hepatocellular carcinoma

Myeloid-derived suppressor cells (MDSCs) play a critical role in maintaining the tumor immune microenvironment; thus, the promotion of MDSC polarization will improve immunotherapies for cancers. However, the mechanisms involved in controlling MDSC polarization in hepatocellular carcinoma remain largely unclear. In this study, we found that injection of Pam3CSK4 attenuated the process of tumor growth, along with reduction of MDSC and recovery of T cell function. Moreover, Pam3CSK4 promoted MDSC polarization by targeting Runx1. Runx1 inhibitor reversed the therapeutic effect of Pam3CSK4 by increasing tumor size and weight and decreasing the survival rate of tumor mice. In addition, targeting Runx1 reduced the expression of CD11c, F4/80, CD80/CD86 and MHC-II in MDSC after Pam3CSK4 stimulation in vivo and in vitro. MDSC also exhibited consistent changes with increasing reactive oxygen species (ROS) production after Pam3CSK4 and Ro5-3335 treatment. RNA sequence data revealed that tfrc, steap3, and gclm were up-regulated in the Pam3CSK4/Ro5-3335 group compared with Pam3CSK4 treatment alone, suggesting that the regulatory effect of TLR2 and Runx1 on MDSC might act through the ferroptosis pathway. Overall, our study has identified a critical role for TLR2 and Runx1 in regulating the differentiation and function of MDSCs and has provided a new mechanism of controlling MDSC polarization during HCC immunotherapy.

Context-dependent functions of pattern recognition receptors in cancer

The immune system plays a critical role in shaping all facets of cancer, from the early initiation stage through to metastatic disease and resistance to therapy. Our understanding of the importance of the adaptive arm of the immune system in antitumour immunity has led to the implementation of immunotherapy with immune checkpoint inhibitors in numerous cancers, albeit with differing efficacy. By contrast, the clinical utility of innate immunity in cancer has not been exploited, despite dysregulated innate immunity being a feature of at least one-third of all cancers associated with tumour-promoting chronic inflammation. The past two decades have seen innate immune pattern recognition receptors (PRRs) emerge as critical regulators of the immune response to microbial infection and host tissue damage. More recently, it has become apparent that in many cancer types, PRRs play a central role in modulating a vast array of tumour-inhibiting and tumour-promoting cellular responses both in immune cells within the tumour microenvironment and directly in cancer cells. Herein, we provide a comprehensive overview of the fast-evolving field of PRRs in cancer, and discuss the potential to target PRRs for drug development and biomarker discovery in a wide range of oncology settings.

A hypoxia-linked gene signature for prognosis prediction and evaluating the immune microenvironment in patients with hepatocellular carcinoma

Background

Previous research indicates that hypoxia critically affects the initiation and progression of hepatocellular carcinoma (HCC). Nevertheless, the molecular mechanisms responsible for HCC development are poorly understood. Herein, we purposed to build a prognostic model using hypoxia-linked genes to predict patient prognosis and investigate the relationship of hypoxia with immune status in the tumor microenvironment (TME).

Methods

The training cohort included transcriptome along with clinical data abstracted from The Cancer Genome Atlas (TCGA). The validation cohort was abstracted from Gene Expression Omnibus (GEO). Univariate along with multivariate Cox regression were adopted to create the prediction model. We divided all patients into low- and high-risk groups using median risk scores. The estimation power of the prediction model was determined with bioinformatic tools.

Results

Six hypoxia-linked genes, HMOX1, TKTL1, TPI1, ENO2, LDHA, and SLC2A1, were employed to create an estimation model. Kaplan-Meier, ROC curve, and risk plot analyses demonstrated that the estimation potential of the risk model was satisfactory. Univariate along with multivariate regression data illustrated that the risk model could independently predict the overall survival (OS). A nomogram integrating the risk signature and clinicopathological characteristics showed a good potential to estimate HCC prognosis. Gene set enrichment analysis (GSEA) revealed that genes associated with cell proliferation and metabolism cascades were abundant in high-risk group. Furthermore, the signature showed a strong ability to distinguish the two groups in terms of immune status.

Conclusions

A prediction model for predicting HCC prognosis using six hypoxia-linked genes was designed in this study, facilitating the diagnosis and treatment of HCC.

TLR2, as a Pathogen Recognition Receptor, Plays Critical Roles in Hepatitis B Outcome

The immune system of active and inactive chronic hepatitis B, as prolonged forms of hepatitis B, is unable to eradicate hepatitis B virus (HBV) from the infected hepatocytes completely. Toll-like receptors (TLRs) play key roles in the viral recognition and promotion of appropriate immune responses. The molecules also participate in the alteration of the target cell functions and transformation. TLR2 is the unique molecule that makes either homodimer or heterodimer with TLR1 and 6 and shows variable roles against viral infections. Therefore, it has been hypothesized that TLR2 may participate in both immune response against HBV and induction of the virus-related hepatic complications. The studies confirm the hypothesis and revealed that TLR2 is not only one of the main molecules altering the course of HBV infection, but also plays key roles in induction of hepatocellular carcinoma (HCC) and liver cirrhosis. However, recent studies demonstrated that the molecule can fight against HCC and liver cirrhosis. Collectively, it appears that nutrition habits, TLR2 gene polymorphisms, gut microbiome, HBV antigens, and activation of other receptors may play key roles in the determination of TLR2 functions.

Interleukin-18 in metabolism: From mice physiology to human diseases

Interleukin-18 (IL-18) is a classical member of the IL-1 superfamily of cytokines. As IL-1β, IL-18 precursor is processed by inflammasome/caspase-1 into a mature and biologically active form. IL-18 binds to its specific receptor composed of two chains (IL-18Rα and IL-18Rβ) to trigger a similar intracellular signaling pathway as IL-1, ultimately leading to activation of NF-κB and inflammatory processes. Independently of this IL-1-like signaling, IL-18 also specifically induces IFN-γ production, driving the Th1 immune response. In circulation, IL-18 binds to the IL-18 binding protein (IL-18BP) with high affinity, letting only a small fraction of free IL-18 able to trigger receptor-mediated signaling. In contrast to other IL-1 family members, IL-18 is produced constitutively by different cell types, suggesting implications in normal physiology. If the roles of IL-18 in inflammatory processes and infectious diseases are well described, recent experimental studies in mice have highlighted the action of IL-18 signaling in the control of energy homeostasis, pancreatic islet immunity and liver integrity during nutritional stress. At the same time, clinical observations implicate IL-18 in various metabolic diseases including obesity, type 1 and 2 diabetes and nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). In the present review, we summarize and discuss both the physiological actions of IL-18 in metabolism and its potential roles in pathophysiological mechanisms leading to the most common human metabolic disorders, such as obesity, diabetes and NAFLD/NASH.

Toll-like receptor 2 signaling in liver pathophysiology

Chronic liver diseases (CLD) are among the major cause of mortality and morbidity worldwide. Despite current achievements in the area of hepatitis virus, chronic alcohol abuse and high-fat diet are still fueling an epidemic of severe liver disease, for which, an effective therapy has yet not been discovered. In particular, the therapeutic regimens that could prevent the progression of fibrosis and, in turn, aid cirrhotic liver to develop a robust regenerative capability are intensively needed. To this context, a better understanding of the signaling pathways regulating hepatic disease development may be of critical value. In general, the liver responds to various insults with an orchestrated healing process involving variety of signaling pathways. One such pathway is the TLR2 signaling pathway, which essentially regulates adult liver pathogenesis and thus has emerged as an attractive target to treat liver disease. TLR2 is expressed by different liver cells, including Kupffer cells (KCs), hepatocytes, and hepatic stellate cells (HSCs). From a pathologic perspective, the crosstalk between antigens and TLR2 may preferentially trigger a distinctive set of signaling mechanisms in these liver cells and, thereby, induce the production of inflammatory and fibrogenic cytokines that can initiate and prolong liver inflammation, ultimately leading to fibrosis. In this review, we summarize the currently available evidence regarding the role of TLR2 signaling in hepatic disease progression. We first elaborate its pathological involvement in liver-disease states, such as inflammation, fibrosis, and cirrhosis. We then discuss how therapeutic targeting of this pathway may help to alleviate its disease-related functioning.

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.

Establishment of interleukin-18 time-resolved fluorescence immunoassay and its preliminary application in liver disease

Background

To establish a time‐resolved fluorescence immunoassay of interleukin (IL)‐18 (IL‐18‐TRFIA) and detect its concentration in different liver disease serum samples.

Methods

The IL‐18 coating antibody and the Eu³⁺‐labeled detection antibody were used for the IL‐18‐TRFIA to detect serum IL‐18 concentration in patients with liver cancer, hepatitis B, hepatitis C, autoimmune hepatitis, fatty liver disease, and healthy controls. The double‐antibody sandwich method was used and methodological evaluation was performed.

Results

The average intra‐ and inter‐assay coefficient of variation for IL‐18‐TRFIA was 4.80% and 5.90%, respectively. The average recovery rate was 106.19 ± 3.44%. The sensitivity (10.96 pg/mL) was higher than that obtained using the ELISA method (62.5 pg/mL). The detection range was 10.96–1000 pg/mL. IL‐6 and galectin‐3 did not cross‐react with IL‐18‐TRFIA. The serum concentration of IL‐18 was (776.99; 653.48–952.39 pg/mL) in hepatitis C, (911; 775.55–1130.03 pg/mL) in fatty liver, (1048.88; 730.04–1185.10 pg/mL) in liver cancer, and (949.12; 723.70–1160.28 pg/mL) in hepatitis B. Moreover, IL‐18 serum levels were significantly higher in patients than the healthy controls (483.09; 402.52–599.70/mL) (p < 0.0001). Autoimmune hepatitis with a serum IL‐18 concentration of 571.62; 502.47–730.31 pg/mL was not significantly different from the healthy controls (p > 0.05).

Conclusion

We established a highly sensitive IL‐18‐TRFIA method that successfully detected serum IL‐18 concentrations in different liver diseases. Furthermore, IL‐18 serum concentration was higher in patients with liver cancer, hepatitis C, hepatitis B, and fatty liver disease compared to healthy controls.

Role of the NLRP3 Inflammasome: Insights Into Cancer Hallmarks

In response to a variety of stresses, mammalian cells activate the inflammasome for targeted caspase-dependent pyroptosis. The research community has recently begun to deduce that the activation of inflammasome is instigated by several known oncogenic stresses and metabolic perturbations; nevertheless, the role of inflammasomes in the context of cancer biology is less understood. In manipulating the expression of inflammasome, researchers have found that NLRP3 serves as a deterministic player in conducting tumor fate decisions. Understanding the mechanistic underpinning of pro-tumorigenic and anti-tumorigenic pathways might elucidate novel therapeutic onco-targets, thereby providing new opportunities to manipulate inflammasome in augmenting the anti-tumorigenic activity to prevent tumor expansion and achieve metastatic control. Accordingly, this review aims to decode the complexity of NLRP3, whereby summarizing and clustering findings into cancer hallmarks and tissue contexts may expedite consensus and underscore the potential of the inflammasome in drug translation.

Gut microbiota mediated molecular events and therapy in liver diseases

Gut microbiota is a community of microorganisms that reside in the gastrointestinal tract. An increasing number of studies has demonstrated that the gut-liver axis plays a critical role in liver homeostasis. Dysbiosis of gut microbiota can cause liver diseases, including nonalcoholic fatty liver disease and alcoholic liver disease. Preclinical and clinical investigations have substantiated that the metabolites and other molecules derived from gut microbiota and diet interaction function as mediators to cause liver fibrosis, cirrhosis, and final cancer. This effect has been demonstrated to be associated with dysregulation of intrahepatic immunity and liver metabolism. Targeting these findings have led to the development of novel preventive and therapeutic strategies. Here, we review the cellular and molecular mechanisms underlying gut microbiota-mediated impact on liver disease. We also summarize the advancement of gut microbiota-based therapeutic strategies in the control of liver diseases.

Modulating the Tumour Microenvironment by Intratumoural Injection of Pattern Recognition Receptor Agonists

Signalling through pattern recognition receptors (PRRs) leads to strong proinflammatory responses, enhancing the activity of antigen presenting cells and shaping adaptive immune responses against tumour associated antigens. Unfortunately, toxicities associated with systemic administration of these agonists have limited their clinical use to date. Direct injection of PRR agonists into the tumour can enhance immune responses by directly modulating the cells present in the tumour microenvironment. This can improve local antitumour activity, but importantly, also facilitates systemic responses that limit tumour growth at distant sites. As such, this form of therapy could be used clinically where metastatic tumour lesions are accessible, or as neoadjuvant therapy. In this review, we summarise current preclinical data on intratumoural administration of PRR agonists, including new strategies to optimise delivery and impact, and combination studies with current and promising new cancer therapies.

Spatial proteome profiling by immunohistochemistry-based laser capture microdissection and data-independent acquisition proteomics

Understanding the tumor heterogeneity through spatially resolved proteome profiling is important for biomedical research and clinical application. Laser capture microdissection (LCM) is a powerful technology for exploring local cell populations without losing spatial information. Conventionally, tissue sections are stained with hematoxylin and eosin (H&E) for cell-type identification before LCM. However, it generally requires experienced pathologists to distinguish different cell types, which limits the application of LCM to broad cancer research field. Here, we designed an immunohistochemistry (IHC)-based workflow for cell type-resolved proteome analysis of tissue samples. Firstly, targeted cell type was marked by IHC using antibody targeting cell-type specific marker to improve accuracy and efficiency of LCM. Secondly, to increase protein recovery from chemically crosslinked IHC tissues, we optimized a decrosslinking procedure to seamlessly combine with the integrated spintip-based sample preparation technology SISPROT. This newly developed approach, termed IHC-SISPROT, has comparable performance as H&E staining-based proteomic analysis. High sensitivity and reproducibility of IHC-SISPROT were achieved by combining with data independent acquisition proteomics. More than 3500 proteins were identified from only 0.2 mm² and 12 μm thickness of hepatocellular carcinoma (HCC) tissue section. Furthermore, using 5 mm² and 12 μm thickness of HCC tissue section, 6660 and 6052 protein groups were quantified from cancer cells and cancer-associated fibroblasts (CAFs) by the IHC-SISPROT workflow. Bioinformatic analysis revealed the enrichment of cell type-specific ligands and receptors and potentially new communications between cancer cells and CAFs by these signaling proteins. Therefore, IHC-SISPROT is a sensitive and accurate proteomic approach for spatial profiling of cell type-specific proteome from tissues.

Harnessing nanomedicine to overcome the immunosuppressive tumor microenvironment

Cancer immunotherapy has received extensive attention due to its ability to activate the innate or adaptive immune systems of patients to combat tumors. Despite a few clinical successes, further endeavors are still needed to tackle unresolved issues, including limited response rates, development of resistance, and immune-related toxicities. Accumulating evidence has pinpointed the tumor microenvironment (TME) as one of the major obstacles in cancer immunotherapy due to its detrimental impacts on tumor-infiltrating immune cells. Nanomedicine has been battling with the TME in the past several decades, and the experience obtained could be exploited to improve current paradigms of immunotherapy. Here, we discuss the metabolic features of the TME and its influence on different types of immune cells. The recent progress in nanoenabled cancer immunotherapy has been summarized with a highlight on the modulation of immune cells, tumor stroma, cytokines and enzymes to reverse the immunosuppressive TME.

ROR-α-1 inhibits the proliferation, invasion, and migration of hepatocellular carcinoma MHCC97H via downregulation of chemokine CXCL5

Hepatocarcinogenesis is a complicated process that is affected by a variety of microenvironmental factors, such as secretory chemokines and cell-extracellular matrix (ECM). Retinoic acid receptor-related orphan receptor (ROR)-α has been shown to attenuate tumor invasiveness by inducing suppressive cell microenvironment, and its low expression was associated with a worse prognosis in HCC patients. In the present study, we attempted to investigate the role and mechanism of the dominant transcript of ROR-α, ROR-α-1, in HCC development and progression. Among the four transcripts (ROR-α-1/-2/-3/-4), overexpression of ROR-α-1 dramatically suppressed the capacity of MHCC97H cells to proliferate, migrate and invade. We analyzed the differentially expressed genes in ROR-α-1-overexpressed and non-overexpressed MHCC97H cells, performed Gene Ontology (GO) enrichment analysis on these differentially-expressed genes, and found out that factors involved in the tumor microenvironment and ECM are related to the anti-tumor effects of ROR-α-1. Among these factors, chemokine CXCL5 was significantly downregulated by ROR-α-1 overexpression. Overexpression of ROR-α-1 remarkably inhibited the capacity of HCC cells to proliferate, migrate, invade, and downregulated the protein levels of β-catenin, c-Myc, Cyclin D1, and N-cadherin, suggesting the tumor-suppressive role of ROR-α-1 in MHCC97H cells. Moreover, overexpression of CXCL5 dramatically attenuated the suppressive effects of cell proliferation, migration and invasion induced by ROR-α-1 overexpression in MHCC97H, suggesting that ROR-α-1 exerts its anti-tumor effects via downregulating CXCL5. In conclusion, we demonstrate the tumor-suppressive role of ROR-α-1 in MHCC97H cells and that ROR-α-1 might play a tumor-suppressive role via regulation of chemokine CXCL5.

Activation of the Toll‑like receptor 2 signaling pathway inhibits the proliferation of HCC cells in vitro

Toll‑like receptor 2 (TLR2), is an important pattern recognition receptor which serves a role in chronic inflammation of the liver. However, the role of TLR2 in the progression of human hepatocellular carcinoma (HCC) remains unknown. The aim of the present study was to examine the effects of the activation of the TLR2 signaling pathway on biological functions, such as proliferation and apoptosis. TLR2 expression in HCC tissues was assayed by quantitative polymerase chain reaction, flow cytometry and western blotting. B76/Huh7 cells were transfected with overexpression plasmids, and cell proliferation was detected using a Cell Counting Kit‑8 assay and the secreted cytokines in the supernatant of transfected cells were measured by ELISA. The findings revealed that TLR2 expression was increased in the peritumoral groups compared with inner‑tumoral groups. Activation of the TLR2 signaling pathway through overexpression of pathway molecules inhibited the growth of B76/Huh7 cells and the secretion of interleukin‑6 and tumor necrosis factor‑α were reduced. Inhibition of the TLR2 signaling pathway resulted in a significant increase in the downstream signaling cascade, thus potentially increasing hepatocarcinogenesis and tumor progression. Activation of the TLR2 signaling pathway may be a potential target for therapeutic intervention in patients with HCC and downstream secreted cytokines are required for the functional biological effect. Therefore, modulation of the TLR2 signaling pathway may provide important insight into designing effective therapeutic regimens for treating patients with HCC.

Current perspectives on the immunosuppressive tumor microenvironment in hepatocellular carcinoma: challenges and opportunities

Incidence of hepatocellular carcinoma (HCC) is on the rise due to the prevalence of chronic hepatitis and cirrhosis. Although there are surgical and chemotherapy treatment avenues the mortality rate of HCC remains high. Immunotherapy is currently the new frontier of cancer treatment and the immunobiology of HCC is emerging as an area for further exploration. The tumor microenvironment coexists and interacts with various immune cells to sustain the growth of HCC. Thus, immunosuppressive cells play an important role in the anti-tumor immune response. This review will discuss the current concepts of immunosuppressive cells, including tumor-associated macrophages, marrow-derived suppressor cells, tumor-associated neutrophils, cancer-associated fibroblasts, and regulatory T cell interactions to actively promote tumorigenesis. It further elaborates on current treatment modalities and future areas of exploration.

Hepatectomy promotes recurrence of liver cancer by enhancing IL-11-STAT3 signaling

Background

Patients undergoing surgical resection of hepatocellular carcinoma (HCC) are at risk of recurrence; however, the underlying mechanism remains poorly understood.

Methods

Through the analysis of gene expression profiles in tumour and matched normal tissues from patients with hepatocellular carcinoma (HCC), we identified differences in interleukin-11 (IL-11) expression. Further, we used genetic mouse, orthotopic tumour, chemically induced, and orthotopic allograft models to study the correlation between IL-11 and postsurgical recurrence. Additionally, we conducted a series of experiments, including histology and immunohistochemistry analysis, three-dimensional culture, immunofluorescence, western blotting, enzyme-linked immunosorbent assay (ELISA) and flow cytometry to investigate the role of IL-11-signal transducer and activator of transcription 3 (STAT3) signaling in HCC recurrence.

Findings

We demonstrate that IL-11 levels increase after surgery, triggering HCC outgrowth. Accordingly, pharmacological blocking of IL-11-STAT3 signaling in model systems significantly alleviates tumour cell proliferation and suppresses postsurgical recurrence of HCC tumours.

Interpretation

These data demonstrate that IL-11 has a central role in postsurgical HCC recurrence, and that inhibition of IL-11-STAT3 signaling is a potential therapeutic strategy to prevent recurrence.

Fund

Natural Science Foundation of China.

Toll-like receptor-induced cytokines as immunotherapeutic targets in cancers and autoimmune diseases

Immune cells of the myeloid and lymphoid lineages express Toll-like receptors (TLRs) to recognize pathogenic components or cellular debris and activate the immune system through the secretion of cytokines. Cytokines are signaling molecules that are structurally and functionally distinct from one another, although their secretion profiles and signaling cascades often overlap. This situation gives rise to pleiotropic cell-to-cell communication pathways essential for protection from infections as well as cancers. Nonetheless, deregulated signaling can have detrimental effects on the host, in the form of inflammatory or autoimmune diseases. Because cytokines are associated with numerous autoimmune and cancerous conditions, therapeutic strategies to modulate these molecules or their biological responses have been immensely beneficial over the years. There are still challenges in the regulation of cytokine function in patients, even in those who take approved biological therapeutics. In this review, our purpose is to discuss the differential expression patterns of TLR-regulated cytokines and their cell type specificity that is associated with cancers and immune-system-related diseases. In addition, we highlight key structural features and molecular recognition of cytokines by receptors; these data have facilitated the development and approval of several biologics for the treatment of autoimmune diseases and cancers.

Systematic Review and Meta-Analysis on the Association between Polymorphisms in Genes of IL-12 Signaling Pathway and Hepatocellular Carcinoma Risk

We performed an updated meta-analysis and systematic review to explore the associations between polymorphisms in genes of IL-12 signaling pathway and hepatocellular carcinoma (HCC) risk. Diverse databases were retrieved to identify entire available studies, and odds ratios (ORs) correspondence with 95% confidence intervals (CIs) were performed to assess their associations. Finally, 6 polymorphisms in five genes of the IL-12 signaling pathway were extracted from 39 case-control studies, 26 publications. We identified that STAT4-rs7574865 polymorphism was significantly associated with an increased risk of HCC in allelic contrast, dominant, homozygote and recessive models. However, we failed to uncover any significant association between other polymorphisms in genes of IL-12 signaling pathway and HCC risk, including IL18-rs1946518 and -rs187238, IFN-γ-rs2430561, IL12A-rs568408, IL12B-rs3212227 and STAT4-rs7574865. When the subgroup analysis was conducted based on Hardy-Weinberg Equilibrium (HWE) status, we identified that IFN-γ-rs2430561 polymorphism was significantly associated with an increased risk of HCC in homozygote and recessive models of these studies whose control groups were conformed to HWE. To sum up, our study suggests that STAT4-rs7574865 is a risk factor for HCC. Further well-designed large sample size studies are warranted to shed new light on these findings.

Differential effects of peptidoglycan on colorectal tumors and intestinal tissue post-pelvic radiotherapy

Immediate medical intervention is required after pelvic tumor radiotherapy to protect the radiosensitive intestine and also to mitigate tumor growth. Toll-like receptors (TLRs) have been shown to promote tissue repair processes. Here, we analyzed the effect observed upon combining the TLR2 agonist, peptidoglycan (PGN), with radiation therapy on tumors as well as intestinal tissue, both in vitro and in vivo. In contrast to radiotherapy alone, PGN when combined with ionizing radiation (IR) elicited enhanced antitumor effects and also reduced the IR-induced intestinal damage. Mechanistic studies showed that PGN first induced an IL13 response in the irradiated intestine, but was decreased in tumor cell models screened by Th1/Th2 FlowCytomix assay and validated by the application of IL13 and anti-IL13 neutralizing antibodies. Next, PGN stimulated Akt3, but not Akt1/2, as was verified by AKT1/2/3 plasmid transfection assay and in AKT1/2/3 knockout mice in vivo. Akt3 expression was inhibited in 20 μg/mL PGN-treated tumor cells and in 1.5 mg/kg PGN-treated mouse tumor models. However, Akt3 was raised via IL13 in the irradiated intestine and human intestinal cell line after the same treatment. Finally, PGN activated mTOR via IL13/AKT3 in the intestine and restored intestinal structure and function. As an adjuvant to radiotherapy, PGN inhibited tumorigenesis by suppression of mTOR activity. To summarize, the IL13/AKT3/mTOR pathway was lessened in PGN-treated irradiated tumors but was raised in the normal intestine tissue. This distinct effect of PGN on normal and tumor tissues during pelvic radiotherapy suggests that PGN may be a promising adjuvant therapy to radiation.

Association of genetic variants in the interleukin-18 gene promoter with risk of hepatocellular carcinoma and metastasis in patients with hepatitis C virus infection

Hepatocellular carcinoma (HCC) is a primary malignancy of the liver, characterized by high vascularization and rapid tumor progression. The current case-control study aimed to analyze the influence of -607C/A and -137G/C polymorphisms in the interleukin-18 (IL-18) promoter on the risk of HCC occurrence and metastasis in Egyptian patients infected with hepatitis C virus (HCV). Both genetic variations were genotyped in 279 subjects including HCV patients with and without HCC and unrelated healthy subjects, using the allele-specific polymerase chain reaction (AS-PCR) method. The relationship between clinico-laboratory parameters including serum level of alpha-fetoprotein (AFP) and these polymorphisms was evaluated in HCC patients. The IL-18-607A allele and AA genotype were significantly related to a higher risk of developing HCC when comparing patients with HCC and controls, and were significantly related to a higher risk of metastasis when comparing metastatic and nonmetastatic groups in the Egyptian patients. In contrast, the IL18-137C allele and GC genotype were significantly related to a lower risk of developing HCC when comparing patients with HCC and controls, and HCV patients with and without HCC. A significant association was found between multinodular HCC and IL-18-607AA genotype, while, uninodular HCC was significantly associated with IL-18-137GG genotype. In addition, IL18-607AA and -137GG genotypes showed significant association with higher level of serum AFP. The detection of polymorphisms in the IL-18 promoter, in a combination with an evaluation of level of serum AFP, could be used as a molecular biomarker in the early diagnosis of HCC, which would aid the early management of the disease, thus decreasing the rate of mortality of this disease. © 2018 IUBMB Life, 70(2):165-174, 2018.

Basic understanding and therapeutic approaches to target toll-like receptors in cancerous microenvironment and metastasis

Toll-like receptors (TLRs) are transmembrane components that sense danger signals, like damage- and pathogen-associated molecular pattern molecules, as receptors, and maintain homeostasis in tissues. They are mainly involved in immune system activation through a variety of mediators, which either carry out (1) elimination of pathogenic threats and redressing homeostatic imbalances or (2) contribution to the initiation and worsening of pathological conditions, including cancers. Under physiological conditions, TLRs coordinate the innate and adaptive immunity, and inhibit autoimmune disorders. In pathological conditions, such as cancer, they can present both tumor and receptor-specific roles. Although the roles of individual TLRs in various cancers have been described, the effects of targeting TLRs to treat cancer and prevent metastasis are still controversial. A growing body of literature has suggested contribution of both activators and inhibitors of TLR signaling pathway for cancer treatment, dependent on several context-specific factors. In short, TLRs can play dual roles with contradictory outcomes in neoplastic conditions. This hampers the development of TLR-based therapeutic interventions. A better understanding of the interwoven TLR pathways in cancerous microenvironment is necessary to design TLR-based therapies. In this review, we consider the molecular mechanisms of TLRs signaling and their involvement in tumor progression. Therapeutic modalities targeting TLRs for cancer treatment are discussed as well.

Tumour-activated liver stromal cells regulate myeloid-derived suppressor cells accumulation in the liver

Regulating mechanisms underlying hepatic myeloid-derived suppressor cell (MDSC) accumulation remain to be described. Here, we provide evidence for the involvement of tumour-activated liver stromal cells in the process of hepatic MDSCs migration and accumulation. Our data showed an elevated frequency of MDSCs in the liver of tumour-bearing mice. Moreover, tumour-activated liver stromal cells promote MDSC migration into the liver site. Further investigation indicated higher levels of cytokine and chemokine expression in liver stromal cells after exposure to the tumour-conditioned supernatant. Notably, the expression levels of proinflammatory factors, mainly including macrophage colony stimulating factor (M-CSF), transforming growth factor-β (TGF-β), monocyte chemotactic protein-1 (MCP-1) and stromal-derived factor-1 (SDF-1), increased after treatment with tumour-conditioned supernatant, and blockade of MCP-1 or SDF-1 decreased the proportion of tumour infiltrated MDSCs in mice co-transplanted with liver stromal cells and tumour cells, but not in mice with only tumour cells injection. These findings demonstrate that tumour-activated liver stromal cells produce higher levels of chemokines and cytokines, which may contribute to MDSC accumulation into the liver site in patients with liver cancer.

PD-L1+MDSCs are increased in HCC patients and induced by soluble factor in the tumor microenvironment

Myeloid-derived suppressor cells (MDSCs) could have important roles in immune regulation, and MDSCs can be induced in patients with various malignant tumors. The immune-suppressive functions of MDSCs in hepatocellular carcinoma (HCC) patients have not been clarified. Therefore, we tried to analyze the biological significance of MDSCs in HCC patients. We quantified PD-L1⁺MDSCs of HCC patients in various conditions by using multi-color flow cytometry analysis. PBMCs from HCC patients contained significantly higher percentages of PD-L1⁺MDSCs in comparison to those from healthy subjects (p < 0.001). The percentages of PD-L1⁺MDSCs were reduced by curative treatment for HCC (p < 0.05), and the percentages of PD-L1⁺MDSCs before treatment were inversely correlated with disease-free survival time. After we cocultivated PBMCs and several liver cancer cell lines in a transwell coculture system, the percentages of PD-L1⁺MDSCs were significantly increased compared with control (p < 0.05). The expression of M-CSF and VEGFA was higher in the cell lines that strongly induced PD-L1⁺MDSCs. Peripheral blood from HCC patients had significantly higher percentages of PD-L1⁺MDSCs in comparison to those of healthy subjects, and the percentages of PD-L1⁺MDSCs were reduced by HCC treatment, suggesting that we might use PD-L1⁺MDSCs as a new biomarker of HCC.

EpCAM Inhibition Sensitizes Chemoresistant Leukemia to Immune Surveillance

The lack of effective tumor-associated antigens restricts the development of targeted therapies against myeloid leukemia. In this study, we compared gene expression patterns of acute myeloid leukemia (AML) and normal bone marrow samples and found that epithelial cell adhesion molecule (EpCAM) is frequently overexpressed in patients with AML, with EpCAM⁺ leukemic cells exhibiting enhanced chemoresistance and oncogenesis. The chemotherapeutic resistance of EpCAM-positive leukemic cells is a consequence of increased WNT5B signaling. Furthermore, we generated EpCAM antibodies that enabled phagocytosis or cytotoxicity of AML cells by macrophage or natural killer cells, respectively. Finally, EpCAM antibody treatment depleted AML in subcutaneous, disseminated, and intramedullary engrafted mice. In summary, EpCAM exhibits promise as a novel target for the treatment of leukemia. Cancer Res; 77(2); 482-93. ©2016 AACR.

HCV-related liver and lymphoproliferative diseases: association with polymorphisms of IL28B and TLR2

To explore the relationship between innate immunity and hepatitis C Virus (HCV) in determining the risk of cirrhosis (CIR), hepatocellular carcinoma (HCC), mixed cryoglobulinemia syndrome (MCS) and non-Hodgkin lymphoma (NHL), we investigated the impact of the toll-like receptor-2 (TLR2) and interleukin-28B (IL28B) genetic variants. TLR2 -174 del variant was associated with TLR2 expression and with specific downstream molecules that drive the expression of different interleukins; rs12979860 Il28B was important in response to interferon-treatment and in spontaneous clearance of HCV. The risk for liver and lymphoproliferative diseases in HCV progression was clarified by stratifying 862 HCV-positive patients into groups based on liver (CIR, HCC) and lymphoproliferative HCV-related diseases (MCS, NHL) and compared with chronic HCV (CHC) infection. Analysis of TLR2-IL28B haplotypes showed an association of wild type haplotype with the lymphoproliferative diseases (OR 1.77, p = 0.029) and a slight increase in HCV viral load (HR 1.38, p = 0.054). Wild type haplotype (TLR2 ins/ins- IL28B C/C) was also found associated with older age in patients with an hepatic diseases (in CIR and in HCC p = 0.038 and p = 0.020, respectively) supporting an effect of innate immunity in the liver disease progression. TLR2 and IL28B polymorphisms in combination showed a role in the control of HCV viral load and different HCV disease progression.

Toll-like receptor stimulation in cancer: A pro- and anti-tumor double-edged sword

Toll-like receptors (TLRs) are a family of transmembrane receptors that recognize various pathogen- and damage-associated molecular pattern molecules playing an important role in inflammation by activating NF-кB. TLRs, mainly expressed by innate immune cells, are involved in inducing and regulating adaptive immune responses. However, the expression of TLRs has also been observed in many tumors, and their stimulation results in tumor progression or regression, depending on the TLR and tumor type. Here we review the role of TLRs in conferring anti- or pro-tumoral effects. The anti-tumoral effects can result from direct induction of tumor cell death and/or activation of efficient anti-tumoral immune responses, and the pro-tumoral effects may be due to inducing tumor cell survival and proliferation or by acting on suppressive or inflammatory immune cells in the tumor microenvironment.

Germline loss of PKM2 promotes metabolic distress and hepatocellular carcinoma

Alternative splicing of the Pkm gene product generates the PKM1 and PKM2 isoforms of pyruvate kinase (PK), and PKM2 expression is closely linked to embryogenesis, tissue regeneration, and cancer. To interrogate the functional requirement for PKM2 during development and tissue homeostasis, we generated germline PKM2-null mice (Pkm2(-/-)). Unexpectedly, despite being the primary isoform expressed in most wild-type adult tissues, we found that Pkm2(-/-) mice are viable and fertile. Thus, PKM2 is not required for embryonic or postnatal development. Loss of PKM2 leads to compensatory expression of PKM1 in the tissues that normally express PKM2. Strikingly, PKM2 loss leads to spontaneous development of hepatocellular carcinoma (HCC) with high penetrance that is accompanied by progressive changes in systemic metabolism characterized by altered systemic glucose homeostasis, inflammation, and hepatic steatosis. Therefore, in addition to its role in cancer metabolism, PKM2 plays a role in controlling systemic metabolic homeostasis and inflammation, thereby preventing HCC by a non-cell-autonomous mechanism.

Re-polarizing Myeloid-derived Suppressor Cells (MDSCs) with Cationic Polymers for Cancer Immunotherapy

Our evolving understandings of cell-material interactions provide insights for using polymers to modulate cell behaviour that may lead to therapeutic applications. It is known that in certain cancers, myeloid-derived suppressor cells (MDSCs) play vital roles in promoting tumour progression, chiefly because of their ‘alternatively activated’ (or M2) phenotype that orchestrates immunosuppression. In this study, we demonstrated that two cationic polymers – cationic dextran (C-dextran) and polyethyleneimine (PEI) – could directly remodel these cells into an anti-tumour, ‘classically activated’ (or M1) phenotype, thereby stimulating these cells to express tumouricidal cytokines, reactivating the T cell functions, and prolonging the lifespan of the mice model. Our investigations with knock-out mice further indicate that the functions of these cationic polymers require the involvement of toll-like receptor 4-mediated signalling. Taken together, our study suggests that these cationic polymers can effectively and directly re-polarize MDSCs from an immunosuppressive characteristic to an anti-tumour phenotype, leading to successful restoration of immune surveillance in the tumour microenvironment and elimination of tumour cells. Our findings may have immediate impact on further development of polymer-based therapeutics for cancer immunotherapy.

Inflammation-Dependent IL18 Signaling Restricts Hepatocellular Carcinoma Growth by Enhancing the Accumulation and Activity of Tumor-Infiltrating Lymphocytes

Chronic inflammation in liver tissue is an underlying cause of hepatocellular carcinoma. High levels of inflammatory cytokine IL18 in the circulation of patients with hepatocellular carcinoma correlates with poor prognosis. However, conflicting results have been reported for IL18 in hepatocellular carcinoma development and progression. In this study, we used tissue specimens from hepatocellular carcinoma patients and clinically relevant mouse models of hepatocellular carcinoma to evaluate IL18 expression and function. In a mouse model of liver fibrosis that recapitulates a tumor-promoting microenvironment, global deletion of the IL18 receptor IL18R1 enhanced tumor growth and burden. Similarly, in a carcinogen-induced model of liver tumorigenesis, IL18R1 deletion increased tumor burden. Mechanistically, we found that IL18 exerted inflammation-dependent tumor-suppressive effects largely by promoting the differentiation, activity, and survival of tumor-infiltrating T cells. Finally, differences in the expression of IL18 in tumor tissue versus nontumor tissue were more predictive of patient outcome than overall tissue expression. Taken together, our findings resolve a long-standing contradiction regarding a tumor-suppressive role for IL18 in established hepatocellular carcinoma and provide a mechanistic explanation for the complex relationship between its expression pattern and hepatocellular carcinoma prognosis. Cancer Res; 76(8); 2394-405. ©2016 AACR.

Innate immunity and hepatocarcinoma: Can toll-like receptors open the door to oncogenesis?

Hepatocarcinoma (HCC) is a highly prevalent cancer worldwide and its inflammatory background was established long ago. Recent studies have shown that innate immunity is closely related to the HCC carcinogenesis. An effective innate immunity response relies on the toll-like receptors (TLR) found in several different liver cells which, through different ligands and many signaling pathways can elicit, not only a pro-inflammatory but also an oncogenic or anti-oncogenic response. Our aim was to study the role of TLRs in the liver oncogenesis and as a consequence their value as potential therapeutic targets. We performed a systematic review of PubMed searching for original articles studying the relationship between HCC and TLRs until March 2015. TLR2 appears to be a fundamental stress-sensor as its absence reveals an augmented tendency to accumulate DNA-damages and to cell survival. However, pathways are still not fully understood as TLR2 up-regulation was also associated to enhanced tumorigenesis. TLR3 has a well-known protective role influencing crucial processes like angiogenesis, cell growth or proliferation. TLR4 works as an interesting epithelial-mesenchymal transition’s inducer and a promoter of cell survival probably inducing HCC carcinogenesis even though an anti-cancer role has already been observed. TLR9’s influence on carcinogenesis is also controversial and despite a potential anti-cancer capacity, a pro-tumorigenic role is more likely. Genetic polymorphisms in some TLRs have been found and its influence on the risk of HCC has been reported. As therapeutic targets, TLRs are already in use and have a great potential. In conclusion, TLRs have been shown to be an interesting influence on the HCC’s microenvironment, with TLR3 clearly determining an anti-tumour influence. TLR4 and TLR9 are considered to have a positive relationship with tumour development even though, in each of them anti-tumorigenic signals have been described. TLR2 presents a more ambiguous role, possibly depending on the stage of the inflammation-HCC axis.

Activation of NLRP3 inflammasome enhances the proliferation and migration of A549 lung cancer cells

Lung cancer is the leading cause of cancer death, and it is widely accepted that chronic inflammation is an important risk for the development of lung cancer. Now, it is recognized that the nucleotide-binding and oligomerization domain (NOD) like receptors (NLRs)-containing inflammasomes are involved in cancer-related inflammation. This study was designed to investigate the effects of NLR family pyrin domain containing protein 3 (NLRP3) inflammasome on the proliferation and migration of lung adenocarcinoma cell line A549. Using 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, scratch assay, and Transwell migration assay, we showed that activation of the NLRP3 inflammasome by LPS+ATP enhanced the proliferation and migration of A549 cells. Western blot analysis showed that activation of phosphorylation of Akt, ERK1/2, CREB and the expression of Snail increased, while the expression of E-cadherin decreased after the activation of NLRP3 inflammasome. Moreover, these effects were inhibited by the following treatments: i) downregulating the expression of NLRP3 by short hairpin RNA (shRNA) interference, ii) inhibiting the activation of NLRP3 inflammasome with a caspase-1 inhibitor, iii) blocking the interleukin-1β (IL-1β) and IL-18 signal transduction with IL-1 receptor antagonist (IL-1Ra) and IL-18 binding protein (IL-18BP). Collectively, these results indicate that NLRP3 inflammasome plays a vital role in regulating the proliferation and migration of A549 cells and it might be a potential target for the treatment of lung cancer.

Association between Interleukin-18 Polymorphisms and Hepatocellular Carcinoma Occurrence and Clinical Progression

We investigated the association between interleukin-18 (IL-18) polymorphisms and the susceptibility and clinicopathological state of hepatocellular carcinoma (HCC). In total, 901 participants, including 559 healthy controls and 342 patients with HCC, were recruited. The allelic discrimination of -607A/C (rs1946518) and -137G/C (rs187238) polymorphisms of IL-18 was assessed through real-time polymerase chain reaction by performing the TaqMan assay. The IL-18 -137G/C polymorphism but not the -607A/C polymorphism showed a significant association with the risk of HCC. Participants carrying the IL-18 -137 polymorphism with heterozygous G/C and homozygous CC genotypes showed a 1.987-fold increase (95% CI = 1.301-3.032; p = 0.001) in the risk of HCC compared with those homozygous for wild-type G/G. The 342 patients with HCC carrying the IL-18 -137G/C polymorphism were positive for hepatitis B virus (HBV) infection with an adjusted odds ratio of 1.668. Moreover, the 142 HBV positive patients with HCC and the IL-18 -137 polymorphism were positive for at least one C genotype and showed significant vascular invasion (p = 0.018). Furthermore, the level of α-fetoprotein was high in the patients carrying the IL-18 -137 polymorphism with GC+CC alleles (p = 0.011). In conclusion, the IL-18 -137G/C polymorphism with a GC+CC genotype could be a factor that increases the risk of HCC. Furthermore, the correlation between the IL-18 -137G/C polymorphism and HCC-related HBV infection is a risk factor for vascular invasion and has a synergistic effect that can further enhance HCC prognosis.

Hepatocytes as Immunological Agents

Hepatocytes are targeted for infection by a number of major human pathogens, including hepatitis B virus, hepatitis C virus, and malaria. However, hepatocytes are also immunological agents in their own right. In systemic immunity, they are central in the acute-phase response, which floods the circulation with defensive proteins during diverse stresses, including ischemia, physical trauma, and sepsis. Hepatocytes express a variety of innate immune receptors and, when challenged with pathogen- or damage-associated molecular patterns, can deliver cell-autonomous innate immune responses that may result in host defense or in immunopathology. Important human pathogens have evolved mechanisms to subvert these responses. Finally, hepatocytes talk directly to T cells, resulting in a bias toward immune tolerance.

Emerging roles of myeloid derived suppressor cells in hepatic inflammation and fibrosis

Myeloid derived suppressor cells (MDSC) are a heterogeneous population of immune cells that are potent suppressors of immune responses. MDSC emerge in various compartments in the body, such as blood, bone marrow or spleen, especially in conditions of cancer, infections or inflammation. MDSC usually express CD11b, CD33, and low levels of human leukocyte antigen-DR in humans or CD11b and Gr1 (Ly6C/G) in mice, and they can be further divided into granulocytic or monocytic MDSC. The liver is an important organ for MDSC induction and accumulation in hepatic as well as extrahepatic diseases. Different hepatic cells, especially hepatic stellate cells, as well as liver-derived soluble factors, including hepatocyte growth factor and acute phase proteins (SAA, KC), can promote the differentiation of MDSC from myeloid cells. Importantly, hepatic myeloid cells like neutrophils, monocytes and macrophages fulfill essential roles in acute and chronic liver diseases. Recent data from patients with liver diseases and animal models linked MDSC to the pathogenesis of hepatic inflammation, fibrosis and hepatocellular carcinoma (HCC). In settings of acute hepatitis, MDSC can limit immunogenic T cell responses and subsequent tissue injury. In patients with chronic hepatitis C, MDSC increase and may favor viral persistence. Animal models of chronic liver injury, however, have not yet conclusively clarified the involvement of MDSC for hepatic fibrosis. In human HCC and mouse models of liver cancer, MDSC are induced in the tumor environment and suppress anti-tumoral immune responses. Thus, the liver is a primary site of MDSC in vivo, and modulating MDSC functionality might represent a promising novel therapeutic target for liver diseases.