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

The role of notch signaling in regulating myeloid-derived suppressor cells: Implications in Cancer and autoimmune diseases

Myeloid-derived suppressor cells (MDSCs) encompass monocytes and granulocytes, which are innate immune cells capable of suppressing T cells and NK cells. MDSCs exert numerous detrimental effects, as they facilitate tumor initiation, promote tumor growth and metastasis, suppress host immune responses, and evade immune surveillance, thereby hindering anticancer responses. Conversely, in autoimmune diseases, MDSCs exhibit dysfunctional immunosuppressive functions and often display pro-inflammatory effects, which can exacerbate immune disorders. We postulate that this discrepancy is attributable to the involvement of the Notch signaling pathway. The Notch signaling pathway is an evolutionarily conserved mechanism that plays a crucial role in maintaining normal mammalian physiological functions. The Notch receptor undergoes three cleavage events before being transported into the nucleus, where it regulates the transcription of target genes. The role of Notch or MDSCs in different diseases has been fully reported, but the regulatory role of Notch signaling pathway on MDSCs in different diseases has been rarely reported.In this review, we characterize the activation, expansion, and immune suppression mechanisms of MDSCs. We then introduce the Notch signaling pathway and finally discuss its role in colorectal cancer, breast cancer, lung cancer, as well as T-cell acute lymphoblastic leukemia, systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. The Notch signaling pathway regulates MDSCs through distinct mechanisms in these contexts. We hope this review will aid both beginners and experts in systematically understanding the regulation of MDSCs by the Notch signaling pathway in cancer and autoimmune diseases.

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Targeting myeloid-derived suppressor cells by inhibiting hypoxia-inducible factor 1α could improve tumor progression

Myeloid-derived suppressor cells (MDSCs) are a subset of immature myeloid cells that inhibit anti-tumor immunity and contribute to poor cancer outcomes. In this study, the authors used multi-color flow cytometry to detect changes in MDSCs in patients with cancer and tumor-bearing mice. Then the authors studied changes in MDSCs ratio and mouse tumors after administration of hypoxia-inducible factor 1α (HIF-1α) inhibitor. The results showed that the ratio of MDSCs, specifically polymorphonuclear MDSCs (PMN-MDSCs), was higher in patients with cancer, and both PMN-MDSCs and monocytic MDSCs (M-MDSCs) ratio were higher in tumor-bearing mice. When provided with the HIF-1α inhibitor LW-6, the ratio of MDSCs decreased in tumor-bearing mice, particularly PMN-MDSCs, and the volume of liver metastases also decreased. The authors' findings suggest that reducing MDSCs by inhibiting hypoxia-inducible factor 1α may slow tumor progression.

The roles of cancer stem cell-derived secretory factors in shaping the immunosuppressive tumor microenvironment in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide and has a poor prognosis. Although immune checkpoint inhibitors have entered a new era of HCC treatment, their response rates are modest, which can be attributed to the immunosuppressive tumor microenvironment within HCC tumors. Accumulating evidence has shown that tumor growth is fueled by cancer stem cells (CSCs), which contribute to therapeutic resistance to the above treatments. Given that CSCs can regulate cellular and physical factors within the tumor niche by secreting various soluble factors in a paracrine manner, there have been increasing efforts toward understanding the roles of CSC-derived secretory factors in creating an immunosuppressive tumor microenvironment. In this review, we provide an update on how these secretory factors, including growth factors, cytokines, chemokines, and exosomes, contribute to the immunosuppressive TME, which leads to immune resistance. In addition, we present current therapeutic strategies targeting CSC-derived secretory factors and describe future perspectives. In summary, a better understanding of CSC biology in the TME provides a rational therapeutic basis for combination therapy with ICIs for effective HCC treatment.

Mechanisms of myeloid-derived suppressor cell-mediated immunosuppression in colorectal cancer and related therapies

Severe immunosuppression is a hallmark of colorectal cancer (CRC). Myeloid-derived suppressor cells (MDSCs), one of the most abundant components of the tumor stroma, play an important role in the invasion, metastasis, and immune escape of CRC. MDSCs create an immunosuppressive microenvironment by inhibiting the proliferation and activation of immunoreactive cells, including T and natural killer cells, as well as by inducing the proliferation of immunosuppressive cells, such as regulatory T cells and tumor-associated macrophages, which, in turn, promote the growth of cancer cells. Thus, MDSCs are key contributors to the emergence of an immunosuppressive microenvironment in CRC and play an important role in the breakdown of antitumor immunity. In this narrative review, we explore the mechanisms through which MDSCs contribute to the immunosuppressive microenvironment, the current therapeutic approaches and technologies targeting MDSCs, and the therapeutic potential of modulating MDSCs in CRC treatment. This study provides ideas and methods to enhance survival rates in patients with CRC.

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.

Myeloid-derived suppressor cells in cancer and cancer therapy

Anticancer agents continue to dominate the list of newly approved drugs, approximately half of which are immunotherapies. This trend illustrates the considerable promise of cancer treatments that modulate the immune system. However, the immune system is complex and dynamic, and can have both tumour-suppressive and tumour-promoting effects. Understanding the full range of immune modulation in cancer is crucial to identifying more effective treatment strategies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid cells that develop in association with chronic inflammation, which is a hallmark of cancer. Indeed, MDSCs accumulate in the tumour microenvironment, where they strongly inhibit anticancer functions of T cells and natural killer cells and exert a variety of other tumour-promoting effects. Emerging evidence indicates that MDSCs also contribute to resistance to cancer treatments, particularly immunotherapies. Conversely, treatment approaches designed to eliminate cancer cells can have important additional effects on MDSC function, which can be either positive or negative. In this Review, we discuss the interplay between MDSCs and various other cell types found in tumours as well as the mechanisms by which MDSCs promote tumour progression. We also discuss the relevance and implications of MDSCs for cancer therapy.

The Roles of Myeloid-Derived Suppressor Cells in Liver Disease

Liver disease-related mortality is a major cause of death worldwide. Hepatic innate and adaptive immune cells play diverse roles in liver homeostasis and disease. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells. MDSCs can be broadly divided into monocytic MDSCs and polymorphonuclear or granulocytic MDSCs, and they functionally interact with both liver parenchymal and nonparenchymal cells, such as hepatocytes and regulatory T cells, to impact liver disease progression. The infiltration and activation of MDSCs in liver disease can be regulated by inflammatory chemokines and cytokines, tumor-associated fibroblasts, epigenetic regulation factors, and gut microbiota during liver injury and cancer. Given the pivotal roles of MDSCs in advanced liver diseases, they can be targeted to treat primary and metastatic liver cancer, liver generation, alcoholic and nonalcoholic liver disease, and autoimmune hepatitis. Currently, several treatments such as the antioxidant and anti-inflammatory agent berberine are under preclinical and clinical investigation to evaluate their therapeutic efficacy on liver disease and their effect on MDSC infiltration and function. Phenotypic alteration of MDSCs in different liver diseases that are in a model-dependent manner and lack special markers for distinct MDSCs are challenges for targeting MDSCs to treat liver disease. Multi-omics study is an option to uncover the features of disease-specific MDSCs and potential gene or protein targets for liver disease treatment. In summary, MDSCs play important roles in the pathogenesis and progression of liver disease by regulating both intrahepatic innate and adaptive immune responses.

Immunomodulatory actions of myeloid-derived suppressor cells in the context of innate immunity

Myeloid-derived suppressor cells (MDSCs) are notable innate immune cells, which are further divided into two subpopulations, i.e., monocytic and granulocytic. These cells are traditionally considered to mainly suppress the T-cell responses. However, more updated data indicate that their properties are rather immunomodulatory than solely immunosuppressive. Indeed, MDSCs display extensive crosstalk with other either innate or adaptive immune cells, and, according to the situation under which they are triggered, they may enhance or attenuate the immune response. However, their positive role in host's defense mechanisms under specific conditions is rarely discussed in the literature. In this mini-review, the authors briefly summarise the mechanisms of action of MDSCs under distinct conditions, such as infections and malignancies, with a particular emphasis on their role as components of the innate immunity system.

The current status and future of PD-L1 in liver cancer

The application of immunotherapy in tumor, especially immune checkpoint inhibitors (ICIs), has played an important role in the treatment of advanced unresectable liver cancer. However, the efficacy of ICIs varies greatly among different patients, which has aroused people's attention to the regulatory mechanism of programmed death ligand-1 (PD-L1) in the immune escape of liver cancer. PD-L1 is regulated by multiple levels and signaling pathways in hepatocellular carcinoma (HCC), including gene variation, epigenetic inheritance, transcriptional regulation, post-transcriptional regulation, and post-translational modification. More studies have also found that the high expression of PD-L1 may be the main factor affecting the immunotherapy of liver cancer. However, what is the difference of PD-L1 expressed by different types of cells in the microenvironment of HCC, and which type of cells expressed PD-L1 determines the effect of tumor immunotherapy remains unclear. Therefore, clarifying the regulatory mechanism of PD-L1 in liver cancer can provide more basis for liver cancer immunotherapy and combined immune treatment strategy. In addition to its well-known role in immune regulation, PD-L1 also plays a role in regulating cancer cell proliferation and promoting drug resistance of tumor cells, which will be reviewed in this paper. In addition, we also summarized the natural products and drugs that regulated the expression of PD-L1 in HCC.

Size-Tunable Nanoregulator-Based Radiofrequency Ablation Suppresses MDSCs and Their Compensatory Immune Evasion in Hepatocellular Carcinoma

Radiofrequency ablation (RFA) is a widely used therapy for hepatocellular carcinoma (HCC). However, in cases of insufficient RFA (iRFA), nonlethal temperatures in the transition zone increase the risk of postoperative relapse. The pathological analysis of HCC tissues shows that iRFA-induced upregulation of myeloid-derived suppressor cells (MDSCs) in residual tumors is critical for postoperative recurrence. Furthermore, this study demonstrates, for the first time, that combining MDSCs suppression strategy during iRFA can unexpectedly lead to a compensatory increase in PD-L1 expression on the residual MDSCs, attributed to relapse due to immune evasion. To address this issue, a novel size-tunable hybrid nano-microliposome is designed to co-deliver MDSCs inhibitors (IPI549) and αPDL1 antibodies (LPIP) for multipathway activation of immune responses. The LPIP is triggered to release immune regulators by the mild heat in the transition zone of iRFA, selectively inhibiting MDSCs and blocking the compensatory upregulation of PD-L1 on surviving MDSCs. The combined strategy of LPIP + iRFA effectively ablates the primary tumor by activating immune responses in the transition zone while suppressing the compensatory immune evasion of surviving MDSCs. This approach avoids the relapse of the residual tumor in a post-iRFA incomplete ablation model and appears to be a promising strategy in RFA for the eradication of HCC.

NLRP3/IL-1β induced myeloid-derived suppressor cells recruitment and PD-L1 upregulation promotes oxaliplatin resistance of hepatocellular carcinoma

Oxaliplatin is commonly used as the first-line chemotherapeutic agent for advanced hepatocellular carcinoma (HCC). Unfortunately, the acquired resistance, limits the effectiveness of oxaliplatin and the underlying mechanisms remain unknown. Therefore, we explored the role of NOD-like receptor protein 3 (NLRP3)/IL-1β in mediating oxaliplatin resistance in HCC. We observed that NLRP3/IL-1β expression was much higher in oxaliplatin-resistant HCC cells. To further understand its impact on drug resistance, we knocked down NLRP3 and observed that it sensitized HCC cells to the growth-inhibitory effects of oxaliplatin and induced cell apoptosis. NLRP3/IL-1β overexpressing tumor cells also attracted polymorphonuclear myeloid-derived suppressor cells. Using mouse models, we demonstrated that NLRP3/IL-1β inhibition by short hairpin RNA or MCC950 effectively overcame oxaliplatin resistance. Furthermore, NLRP3/IL-1β inhibition resulted in reduced expression of PD-L1. We also found that PD-L1 antibody combined with NLRP3/IL-1β blockade displayed significant antitumor effect in HCC. Overall, our study provides compelling evidence supporting the essential role of NLRP3/IL-1β in conferring resistance to oxaliplatin and reshaping the immunosuppressive microenvironment in HCC. Targeting NLRP3/IL-1β presents a potential therapeutic target for overcoming oxaliplatin resistance and reshaping microenvironment of HCC.

Progress in research on the role played by myeloid-derived suppressor cells in liver diseases

Myeloid-derived suppressor cells (MDSCs) refer to a group of immature myeloid cells with potent immunosuppressive capacity upon activation by pathological conditions. Because of their potent immunosuppressive ability, MDSCs have garnered extensive attention in the past few years in the fields of oncology, infection, chronic inflammation and autoimmune diseases. Research on MDSCs in liver diseases has gradually increased, and their potential therapeutic roles will be further explored. This review presents a summary of the involvement and the role played by MDSCs in liver diseases, thus identifying their potential targets for the treatment of liver diseases and providing new directions for liver disease-related research.

The distribution of myeloid-derived suppressor cells subsets and up-regulation of programmed death-1/PD-L1 axis in peripheral blood of adult CAP patients

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) have been reported to expand and have a potent ability in the expansion of regulatory T cells in malignant and infectious disease. The current study was performed to investigate the role of MDSCs and possible immune mechanisms in dampening immune responses of community acquired pneumonia (CAP).

METHODS

This was a single-center cross-sectional study. The distribution of MDSCs subsets, the PD-1/PD-L1(L2) level of MDSCs subsets and Tregs in the peripheral blood of adult CAP patients and healthy control were measured by flow cytometry analysis.

RESULTS

Peripheral blood mononuclear cells (PBMCs) from 63 adult CAP patients contained an elevated frequency of both G-MDSC (4.92±0.30 vs 2.25±0.21,p<0.0001) and M-MDSC (19.40±1.30 vs 9.64±0.57,p<0.001) compared to healthy controls. Treg in the peripheral blood of CAP patients exhibited increased expression of PD-1 and CTLA-4, accompanied by no difference of their frequency. Moreover, up-regulated expression of PD-L1 on MDSC subsets in the peripheral blood of CAP patients was also revealed. Of note, the frequency of circulating MDSCs subset displayed a positive correlation with neutrophil count percentage in blood in CAP patients.

CONCLUSIONS

In summary, the significant expansion of circulating MDSCs subsets and the up-regulated expression of PD-1/PD-L1 level in CAP patients may suggest the possible involvement of PD-1/PD-L1axis in MDSCs mediated immune regulation on Treg at least partially in CAP patients.

From Reductionistic Approach to Systems Immunology Approach for the Understanding of Tumor Microenvironment

The tumor microenvironment (TME) is a complex and dynamic ecosystem that includes a variety of immune cells mutually interacting with tumor cells, structural/stromal cells, and each other. The immune cells in the TME can have dual functions as pro-tumorigenic and anti-tumorigenic. To understand such paradoxical functions, the reductionistic approach classifies the immune cells into pro- and anti-tumor cells and suggests the therapeutic blockade of the pro-tumor and induction of the anti-tumor immune cells. This strategy has proven to be partially effective in prolonging patients' survival only in a fraction of patients without offering a cancer cure. Recent advances in multi-omics allow taking systems immunology approach. This essay discusses how a systems immunology approach could revolutionize our understanding of the TME by suggesting that internetwork interactions of the immune cell types create distinct collective functions independent of the function of each cellular constituent. Such collective function can be understood by the discovery of the immunological patterns in the TME and may be modulated as a therapeutic means for immunotherapy of cancer.

Recent Advances in Image-Guided Locoregional Therapies for Primary Liver Tumors

Primary liver cancer is the leading cause of cancer-related deaths worldwide. with incidences predicted to rise over the next several decades. Locoregional therapies, such as radiofrequency or microwave ablation, are described as image-guided percutaneous procedures, which offer either a curative intent for early-stage hepatocellular carcinoma or bridging/downstaging for surgical resection or transplantation. Catheter-driven locoregional therapies, such as transarterial chemoembolization and radioembolization, induce tumor hypoxia, can be palliative, and improve survival for early-to-intermediate hepatocellular carcinoma and unresectable intrahepatic cholangiocarcinoma. Herein, we provide a comprehensive overview of the antineoplastic mechanisms underpinning locoregional therapies, different treatment approaches, and the current state of the literature for the efficacy of locoregional therapies for primary liver cancer. We also discuss emerging advancements, such as the adjuvant use of immunotherapies and molecular targeting agents with locoregional therapy, for the treatment of primary liver cancer.

Modulation of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment by Natural Products

During carcinogenesis, the microenvironment plays a fundamental role in tumor progression and resistance. This tumor microenvironment (TME) is characterized by being highly immunosuppressive in most cases, which makes it an important target for the development of new therapies. One of the most important groups of cells that orchestrate immunosuppression in TME is myeloid-derived suppressor cells (MDSCs), which have multiple mechanisms to suppress the immune response mediated by T lymphocytes and thus protect the tumor. In this review, we will discuss the importance of modulating MDSCs as a therapeutic target and how the use of natural products, due to their multiple mechanisms of action, can be a key alternative for modulating these cells and thus improve response to therapy in cancer patients.

Low-Baseline PD1+ Granulocytes Predict Responses to Atezolizumab-Bevacizumab in Hepatocellular Carcinoma

INTRODUCTION

Immune check point inhibitors have recently entered the armamentarium of advanced hepatocellular carcinoma (HCC) treatment. Among them, the combination of atezolizumab plus bevacizumab has pushed it a step forward; however, a number of patients still present primary non-responses without any biomarker to predict responses to different options. Here, we aimed to identify a putative baseline biomarker to predict the response to atezolizumab-bevacizumab, by investigating whether baseline PD1+ and PD-L1+ peripheral granulocyte percentages might offer a non-invasive, cheap, and easily feasible assay.

METHODS

A prospective Italian cohort of 34 patients treated by atezolizumab-bevacizumab was tested to assay the baseline percentage of peripheral granulocytes and their PD1 and PD-L1 expression. The neutrophil to lymphocyte ratio (NLR) was also considered, and all data were compared with the clinical course of patients.

RESULTS

A low-baseline PD1+ peripheral granulocyte percentage turned out to predict responder patients (mean ±SD of PD1+ granulocyte percentage in responders versus non-responders: 9.9 ± 9.1 vs. 29.2 ± 17.6; student's t-test, p < 0.01). In line, patients identified by a low PD1+ granulocyte percentage displayed a longer TTP (log-rank test, p < 0.0001). A lower granulocyte percentage on total white blood cells, irrespective of PD1 or PD-L1 expression, is also associated with responses to atezolizumab-bevacizumab (log-rank test, p < 0.05). No predictive value was observed for either the PD-L1+ granulocyte percentage or NLR.

CONCLUSIONS

A low-baseline PD1+ peripheral granulocyte percentage is associated with responses to atezolizumab-bevacizumab treatment in advanced HCC. These findings encourage evaluating this minimally invasive, cheap, and easy test in further independent cohorts and outlining the relevance of innate immunity in the response to immune-checkpoint inhibitors.

Tumor microenvironment-mediated immune evasion in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and is the third leading cause of tumor-related mortality worldwide. In recent years, the emergency of immune checkpoint inhibitor (ICI) has revolutionized the management of HCC. Especially, the combination of atezolizumab (anti-PD1) and bevacizumab (anti-VEGF) has been approved by the FDA as the first-line treatment for advanced HCC. Despite great breakthrough in systemic therapy, HCC continues to portend a poor prognosis owing to drug resistance and frequent recurrence. The tumor microenvironment (TME) of HCC is a complex and structured mixture characterized by abnormal angiogenesis, chronic inflammation, and dysregulated extracellular matrix (ECM) remodeling, collectively contributing to the immunosuppressive milieu that in turn prompts HCC proliferation, invasion, and metastasis. The tumor microenvironment coexists and interacts with various immune cells to maintain the development of HCC. It is widely accepted that a dysfunctional tumor-immune ecosystem can lead to the failure of immune surveillance. The immunosuppressive TME is an external cause for immune evasion in HCC consisting of 1) immunosuppressive cells; 2) co-inhibitory signals; 3) soluble cytokines and signaling cascades; 4) metabolically hostile tumor microenvironment; 5) the gut microbiota that affects the immune microenvironment. Importantly, the effectiveness of immunotherapy largely depends on the tumor immune microenvironment (TIME). Also, the gut microbiota and metabolism profoundly affect the immune microenvironment. Understanding how TME affects HCC development and progression will contribute to better preventing HCC-specific immune evasion and overcoming resistance to already developed therapies. In this review, we mainly introduce immune evasion of HCC underlying the role of immune microenvironment, describe the dynamic interaction of immune microenvironment with dysfunctional metabolism and the gut microbiome, and propose therapeutic strategies to manipulate the TME in favor of more effective immunotherapy.

Emerging Insights on Immunotherapy in Liver Cancer

Significance: Hepatocellular carcinoma (HCC) is a liver malignancy with high mortality rate, limited treatment options, and poor prognosis. Sorafenib has been the only systemic treatment option for patients with advanced HCC for more than a decade. HCC is a typical inflammation-related tumor with a distinct immunosuppressive microenvironment especially the upregulation of immune checkpoints. Recent Advances: Immunotherapy has shown persistent and powerful efficacy in HCC treatment. Several preclinical and clinical studies have prompted the application of immunotherapy in first-line, second-line, and postline treatment of HCC, which has profoundly shifted the paradigm for advanced HCC treatment in the past few years. Critical Issues and Future Directions: Major unaddressed challenges in HCC immunotherapy include the discovery and validation of biological markers that predict the efficacy, the application of immunotherapy in patients with impaired liver function and nonalcoholic steatohepatitis-associated HCC, and the exploration of immunotherapy combinations with better effectiveness. This review provides the latest advances in the research of immune microenvironment and immunotherapy in HCC. Antioxid. Redox Signal. 37, 1325-1338.

Myeloid derived suppressor cells in tumor microenvironment: Interaction with innate lymphoid cells

Human myeloid-derived suppressor cells (MDSC) represent a stage of immature myeloid cells and two main subsets can be identified: monocytic and polymorphonuclear. MDSC contribute to the establishment of an immunosuppressive tumor microenvironment (TME). The presence and the activity of MDSC in patients with different tumors correlate with poor prognosis. As previously reported, MDSC promote tumor growth and use different mechanisms to suppress the immune cell-mediated anti-tumor activity. Immunosuppression mechanisms used by MDSC are broad and depend on their differentiation stage and on the pathological context. It is known that some effector cells of the immune system can play an important role in the control of tumor progression and metastatic spread. In particular, innate lymphoid cells (ILC) contribute to control tumor growth representing a potential, versatile and, immunotherapeutic tool. Despite promising results obtained by using new cellular immunotherapeutic approaches, a relevant proportion of patients do not benefit from these therapies. Novel strategies have been investigated to overcome the detrimental effect exerted by the immunosuppressive component of TME (i.e. MDSC). In this review, we summarized the characteristics and the interactions occurring between MDSC and ILC in different tumors discussing how a deeper knowledge on MDSC biology could represent an important target for tumor immunotherapy capable of decreasing immunosuppression and enhancing anti-tumor activity exerted by immune cells.

DEB-TACE combined with hepatic artery infusion chemotherapy might be an affordable treatment option for advanced stage of HCC

Alternative treatment modalities are necessary because of the low response rates and unsuitability of molecular-targeted agents (MTA) and/or immune checkpoint inhibitors (iCIs) in HCC patients. Therefore, we analyzed whether drug-eluting beads (DEB)-transcatheter arterial chemoembolization (TACE) with low-dose-FP (Ultra-FP) therapy could improve the efficacy and safety of treatment in difficult-to-treat HCC patients, especially those with advanced stage HCC. From November 2017 to April 2021, 118 consecutive patients with non-resectable difficult-to-treat HCC were included in this study. All patients were treated with Ultra-FP therapy. After the weak DEB-TACE procedure, we administered low-dose FP for 2 weeks followed by resting for 4 weeks. The numbers of HCC patients CR/PR/SD/PD induced by Ultra-FP therapy were 36/52/17/13 (Modified RECIST) patients, respectively. The objective response rate of Ultra-FP therapy was 74.6% (88/118 patients). Tumor marker reduction was observed in 81.4% (96/118 patients). The objective response rate (ORR) in the HCC patients with portal vein tumor thrombosis (PVTT) was 75% (18/24 patients). Median overall survival (mOS) of all included HCC patients was 738 days. The mOS of HCC patients with PVTT (-)/PVTT (+) was 816 days/718 days. The proportion of patients based on ALBI grade system was not significantly different between pre- and after 3 course Ultra-FP therapy. Ultra-FP therapy might be an affordable treatment option for difficult-to-treat advanced HCC. ORR and overall survival after receiving Ultra-FP therapy were remarkable in comparison to various kinds of systemic therapy including MTA and iCIs.

Treatment of Multiple Primary Malignancies With PD-1 Inhibitor Camrelizumab: A Case Report and Brief Literature Review

Background

With significant advances in the diagnostic tools and treatment modalities of cancer, the incidence of multiple primary malignancies (MPMs) has increased in the last decades. The therapeutic option changed with the arising of immune checkpoint inhibitors (ICIs), which have improved the survival of a broad spectrum of tumors. However, little information is available when it comes to the efficacy, resistance, and underlying mechanisms of ICIs.

Case Presentation

A 67-year-old woman was diagnosed with pulmonary sarcomatoid carcinoma (PSC) with a history of hepatocellular carcinoma (HCC) and viral hepatitis B. Following the lack of response to systemic chemotherapy, she was treated with camrelizumab, an anti-programmed cell death protein 1 monoclonal antibody, in combination with chemotherapy, and a partial response was obtained both in PSC and HCC. After a course of 9-month treatment, the PSC lesion shrank still, while HCC was evaluated as a progressive disease with an increase in the diameter of liver neoplasm, elevated alpha-fetoprotein, and enlarged abdominal lymph nodes. Then, with the addition of radiotherapy for abdominal metastasis, the lung lesion was continuously shrinking. In the meantime, the liver neoplasm and abdominal lymph nodes showed no significant enlargement.

Conclusion

Camrelizumab combination therapy could consistently benefit the MPM patients with PSC and HCC, which may be a promising option for patients with MPMs.

Myeloid derived suppressor cells and innate immune system interaction in tumor microenvironment

The tumor microenvironment is a complex domain that not only contains tumor cells but also a plethora of other host immune cells. By nature, the tumor microenvironment is a highly immunosuppressive milieu providing growing conditions for tumor cells. A major immune cell population that contributes most in the development of this immunosuppressive microenvironment is the MDSC, a heterogenous population of immature cells. Although found in small numbers only in the bone marrow of healthy individuals, they readily migrate to the lymph nodes and tumor site during cancer pathogenesis. MDSC mediated disruption of antitumor T cell activity is a major cause of the immunosuppression at the tumor site, but recent findings have shown that MDSC mediated dysfunction of other major immune cells might also play an important role. In this article we will review how crosstalk with MDSC alters the activity of both conventional and unconventional immune cells that inhibits the antitumor immunity and promotes cancer progression.

Splenic and PB immune recovery in neoadjuvant treated gastrointestinal cancer patients

In recent years, immune therapy, notably immune checkpoint inhibitors (ICI), in conjunction with chemotherapy and surgery has demonstrated therapeutic activity for some tumor types. However, little is known about the optimal combination of immune therapy with standard of care therapies and approaches. In patients with gastrointestinal (GI) cancers, especially pancreatic ductal adenocarcinoma (PDAC), preoperative (neoadjuvant) chemotherapy has increased the number of patients who can undergo surgery and improved their responses. However, most chemotherapy is immunosuppressive, and few studies have examined the impact of neoadjuvant chemotherapy (NCT) on patient immunity and/or the optimal combination of chemotherapy with immune therapy. Furthermore, the majority of chemo/immunotherapy studies focused on immune regulation in cancer patients have focused on postoperative (adjuvant) chemotherapy and are limited to peripheral blood (PB) and occasionally tumor infiltrating lymphocytes (TILs); representing a minority of immune cells in the host. Our previous studies examined the phenotype and frequencies of myeloid and lymphoid cells in the PB and spleens of GI cancer patients, independent of chemotherapy regimen. These results led us to question the impact of NCT on host immunity. We report herein, unique studies examining the splenic and PB phenotypes, frequencies, and numbers of myeloid and lymphoid cell populations in NCT treated GI cancer patients, as compared to treatment naïve cancer patients and patients with benign GI tumors at surgery. Overall, we noted limited immunological differences in patients 6 weeks following NCT (at surgery), as compared to treatment naive patients, supporting rapid immune normalization. We observed that NCT patients had a lower myeloid derived suppressor cells (MDSCs) frequency in the spleen, but not the PB, as compared to treatment naive cancer patients and patients with benign GI tumors. Further, NCT patients had a higher splenic and PB frequency of CD4+ T-cells, and checkpoint protein expression, as compared to untreated, cancer patients and patients with benign GI tumors. Interestingly, in NCT treated cancer patients the frequency of mature (CD45RO+) CD4+ and CD8+ T-cells in the PB and spleens was higher than in treatment naive patients. These differences may also be associated, in part with patient stage, tumor grade, and/or NCT treatment regimen. In summary, the phenotypic profile of leukocytes at the time of surgery, approximately 6 weeks following NCT treatment in GI cancer patients, are similar to treatment naive GI cancer patients (i.e., patients who receive adjuvant therapy); suggesting that NCT may not limit the response to immune intervention and may improve tumor responses due to the lower splenic frequency of MDSCs and higher frequency of mature T-cells.

Natural Killer Cells in the Malignant Niche of Multiple Myeloma

Natural killer (NK) cells represent a subset of CD3- CD7+ CD56+/dim lymphocytes with cytotoxic and suppressor activity against virus-infected cells and cancer cells. The overall potential of NK cells has brought them to the spotlight of targeted immunotherapy in solid and hematological malignancies, including multiple myeloma (MM). Nonetheless, NK cells are subjected to a variety of cancer defense mechanisms, leading to impaired maturation, chemotaxis, target recognition, and killing. This review aims to summarize the available and most current knowledge about cancer-related impairment of NK cell function occurring in MM.

Anti-nuclear antibody and a granuloma could be biomarkers for iCIs-related hepatitis by anti-PD-1 treatment

It has been reported that various kinds of immune checkpoint inhibitors (iCIs) could induce immune-related liver damage. We should focus on the programmed cell death-receptor-1 (PD-1) antibody and non-small cell lung cancer (NSCLC) to analyze the characteristics of hepatitis related to iCIs and find factors that could be useful biomarkers for the diagnosis. A single-center retrospective study of 252 NSCLC patients who received PD-1 antibody (nivolumab or pembrolizumab). Some of the biochemical markers and immunological markers were analyzed during PD-1-antibody treatment with or without ALT elevation. Histopathological features were reviewed by a single expert of hepatic pathology focusing on the following features: fibrosis, portal inflammation, lobular inflammation, lobular necrosis. The formation of macro- and micro-granulomas was also evaluated. The frequency of liver damage induced by nivolumab including grade 1 to 4 (ALT) was 41.9% (78/186 patients). The positive rate of anti-nuclear antibody in the nivolumab group with iCIs-related hepatitis was significantly higher than that in the nivolumab group without iCIs-related hepatitis (p = 0.00112). Granulomatous changes were significantly increased in patients with iCIs-related hepatitis compared with DILI and AIH patients (p < 0.05). The ratios of inflammatory cells CD4/CD8, and CD138/CD3 in ICIs-related hepatitis were significantly lower than those in AIH or DILI patients (p < 0.05). We demonstrated that the pre-existing ANA and characteristic liver histology including CD8+ cells dominancy and granulomatous hepatitis could be biomarkers for the diagnosis of iCIs-related hepatitis in the NSCLC with anti-PD-1 therapy.

Pivotal antitumor role of the immune checkpoint molecule B7-H1 in pancreatic cancer

Immune checkpoint molecule B7-H1 plays a decisive immune regulatory role in different pathologies including cancer, and manipulation of B7-H1 expression became an attractive approach in cancer immunotherapy. Pancreatic cancer (PDAC) is characterized by pronounced immunosuppressive environment and B7-H1 expression correlates with PDAC prognosis. However, the first attempts to diminish B7-H1 expression in patients were not so successful. This points the complicity of PDAC immunosuppressive network and requires further examinations. We investigated the effect of B7-H1 deficiency in PDAC. Our results clearly show that partial or complete B7-H1 inhibition in vivo let to reduced tumor volume and improved survival of PDAC-bearing mice. This oncological benefit is due to the abrogation of immunosuppression provided by MDSC, macrophages, DC and Treg, which resulted in simultaneous restoration of anti-tumor immune response, namely improved accumulation and functionality of effector-memory CD4 and CD8 T cells. Our results underline the potential of B7-H1 molecule to control immunosuppressive network in PDAC and provide new issues for further clinical investigations.

Regulating Histone Deacetylase Signaling Pathways of Myeloid-Derived Suppressor Cells Enhanced T Cell-Based Immunotherapy

Immunotherapy has emerged as a promising approach to combat immunosuppressive tumor microenvironment (TME) for improved cancer treatment. FDA approval for the clinical use of programmed death receptor 1/programmed death-ligand 1 (PD-1/PD-L1) inhibitors revolutionized T cell-based immunotherapy. Although only a few cancer patients respond to this treatment due to several factors including the accumulation of immunosuppressive cells in the TME. Several immunosuppressive cells within the TME such as regulatory T cells, myeloid cells, and cancer-associated fibroblast inhibit the activation and function of T cells to promote tumor progression. The roles of epigenetic modifiers such as histone deacetylase (HDAC) in cancer have long been investigated but little is known about their impact on immune cells. Recent studies showed inhibiting HDAC expression on myeloid-derived suppressor cells (MDSCs) promoted their differentiation to less suppressive cells and reduced their immunosuppressive effect in the TME. HDAC inhibitors upregulated PD-1 or PD-L1 expression level on tumor or immune cells sensitizing tumor-bearing mice to anti-PD-1/PD-L1 antibodies. Herein we discuss how inhibiting HDAC expression on MDSCs could circumvent drawbacks to immune checkpoint inhibitors and improve cancer immunotherapy. Furthermore, we highlighted current challenges and future perspectives of HDAC inhibitors in regulating MDSCs function for effective cancer immunotherapy.

The role of myeloid-derived suppressor cells in lung cancer and targeted immunotherapies

INTRODUCTION

Lung cancer is the deadliest cancer in both sexes combined globally due to significant delays in diagnosis and poor survival. Despite advances in the treatment of lung cancer, the overall outcomes remain poor and traditional chemotherapy fails to provide long-term benefits for many patients. Therefore, new treatment strategies are needed to increase overall survival. Myeloid-derived suppressor cells (MDSCs) are immunosuppressive cells taking part in lung cancer, as has been described in other types of tumors. MDSCs immunosuppressive activity is mediated by arginases (ARG-1 and ARG-2), nitric oxide (NO), reactive oxygen species (ROS), peroxynitrite, PD-1/PD-L1 axis, and different cytokines. MDSCs can be a target for lung cancer immunotherapy by inducing their differentiation into mature myeloid cells, elimination, attenuation of their function, and inhibition of their accumulation.

AREAS COVERED

In this review, the immunosuppressive function of MDSCs, their role in lung cancer, and strategies to target them, which could result in increased efficacy of immunotherapy in patients with lung cancer, are discussed.

EXPERT OPINION

Identification of important mechanisms and upstream pathways involved in MDSCs functions paves the way for further preclinical and clinical lung cancer research, which could lead to the development of novel therapeutic approaches.

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.

Azoximer Bromide: Mystery, Serendipity, and Promise

Azoximer bromide (AZB) was identified as an immunomodulator, and was initially developed and currently successfully indicated as one of several natural polyelectrolytes, a vaccine adjuvant, and an effective agent for the treatment of infectious and inflammatory diseases of viral, bacterial, and fungal origin. AZB has the potential to increase an individual's resistance to local and general infection and is indicated for the treatment of viral infections, and has also demonstrated clinical efficacy in the treatment of a variety of secondary immunodeficiencies. However, AZB may offer long-term promise beyond use against infection. Multiple clinical trials and research studies in cancer patients have reported favourable outcomes with AZB as well as an optimal safety and tolerability profile. The findings raise the possibility of direct antitumor properties. This literature review analyses the novel mechanisms that mediate the AZB direct anticancer effects. Overall, the evidence suggests that AZB has the hallmark of an agent that could be used to support existing cancer treatments at different stages of disease.

Hijacked Immune Cells in the Tumor Microenvironment: Molecular Mechanisms of Immunosuppression and Cues to Improve T Cell-Based Immunotherapy of Solid Tumors

The understanding of the tumor microenvironment (TME) has been expanding in recent years in the context of interactions among different cell types, through direct cell–cell communication as well as through soluble factors. It has become evident that the development of a successful antitumor response depends on several TME factors. In this context, the number, type, and subsets of immune cells, as well as the functionality, memory, and exhaustion state of leukocytes are key factors of the TME. Both the presence and functionality of immune cells, in particular T cells, are regulated by cellular and soluble factors of the TME. In this regard, one fundamental reason for failure of antitumor responses is hijacked immune cells, which contribute to the immunosuppressive TME in multiple ways. Specifically, reactive oxygen species (ROS), metabolites, and anti-inflammatory cytokines have central roles in generating an immunosuppressive TME. In this review, we focused on recent developments in the immune cell constituents of the TME, and the micromilieu control of antitumor responses. Furthermore, we highlighted the current challenges of T cell-based immunotherapies and potential future strategies to consider for strengthening their effectiveness.

Identification of BHLHE40 expression in peripheral blood mononuclear cells as a novel biomarker for diagnosis and prognosis of hepatocellular carcinoma

Novel and sensitive biomarkers is highly required for early detection and predicting prognosis of hepatocellular carcinoma (HCC). Here, we investigated transcription profiles from peripheral blood mononuclear cells (PBMCs) of 8 patients with HCC and PBMCs from co-culture model with HCC using RNA-Sequencing. These transcription profiles were cross compared with published microarray datasets of PBMCs in HCC to identify differentially expressed genes (DEGs). A total of commonly identified of 24 DEGs among these data were proposed as cancer-induced genes in PBMCs, including 18 upregulated and 6 downregulated DEGs. The KEGG pathway showed that these enriched genes were mainly associated with immune responses. Five up-regulated candidate genes including BHLHE40, AREG, SOCS1, CCL5, and DDIT4 were selected and further validated in PBMCs of 100 patients with HBV-related HCC, 100 patients with chronic HBV infection and 100 healthy controls. Based on ROC analysis, BHLHE40 and DDIT4 displayed better diagnostic performance than alpha-fetoprotein (AFP) in discriminating HCC from controls. Additionally, BHLHE40 and DDIT4 had high sensitivity for detecting AFP-negative and early-stage HCC. BHLHE40 was also emerged as an independent prognostic factor of overall survival of HCC. Together, our study indicated that BHLHE40 in PBMCs could be a promising diagnostic and prognostic biomarker for HBV-related HCC.

PD-1/PD-L1 in Cancer: Pathophysiological, Diagnostic and Therapeutic Aspects

Immune evasion is a key strategy adopted by tumor cells to escape the immune system while promoting their survival and metastatic spreading. Indeed, several mechanisms have been developed by tumors to inhibit immune responses. PD-1 is a cell surface inhibitory receptor, which plays a major physiological role in the maintenance of peripheral tolerance. In pathological conditions, activation of the PD-1/PD-Ls signaling pathway may block immune cell activation, a mechanism exploited by tumor cells to evade the antitumor immune control. Targeting the PD-1/PD-L1 axis has represented a major breakthrough in cancer treatment. Indeed, the success of PD-1 blockade immunotherapies represents an unprecedented success in the treatment of different cancer types. To improve the therapeutic efficacy, a deeper understanding of the mechanisms regulating PD-1 expression and signaling in the tumor context is required. We provide an overview of the current knowledge of PD-1 expression on both tumor-infiltrating T and NK cells, summarizing the recent evidence on the stimuli regulating its expression. We also highlight perspectives and limitations of the role of PD-L1 expression as a predictive marker, discuss well-established and novel potential approaches to improve patient selection and clinical outcome and summarize current indications for anti-PD1/PD-L1 immunotherapy.

Elevated M-MDSCs in Circulation Are Indicative of Poor Prognosis in Diffuse Large B-Cell Lymphoma Patients

Myeloid-derived suppressor cells (MDSCs) are defined as negative regulators that suppress the immune response through a variety of mechanisms, which usually cluster in cancer, inflammation, and autoimmune diseases. This study aims to investigate the correlation between M-MDSCs and the clinical features of diffuse large B-cell lymphoma (DLBCL) patients, as well as the possible accumulation mechanism of M-MDSCs. The level of M-MDSCs is significantly increased in newly diagnosed and relapsed DLBCL patients. Regarding newly diagnosed DLBCL patients, the frequency of M-MDSCs is positively correlated with tumor progression and negatively correlated with overall survival (OS). More importantly, the level of M-MDSCs can be defined as a biomarker for a poor prognosis in DLBCL patients. Additionally, interleukin-35 (IL-35) mediates the accumulation of M-MDSCs in DLBCL patients. Anti-IL-35 treatment significantly reduces levels of M-MDSCs in Ly8 tumor-bearing mice. Thus, M-MDSCs are involved in the pathological process of DLBCL. Targeting M-MDSCs may be a promising therapeutic strategy for the treatment of DLBCL patients.

The role of myeloid-derived suppressor cells in gastrointestinal cancer

Gastrointestinal (GI) cancer encompasses a range of malignancies that originate in the digestive system, which together represent the most common form of cancer diagnosed worldwide. However, despite numerous advances in both diagnostics and treatment, the incidence and mortality rate of GI cancer are on the rise. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that increase in number under certain pathological conditions, such as infection and inflammation, and this expansion is of particular relevance to cancer. MDSCs are heavily involved in the regulation of the immune system and act to dampen its response to tumors, favoring the escape of tumor cells from immunosurveillance and increasing both metastasis and recurrence. Several recent studies have supported the use of MDSCs as a prognostic and predictive biomarker in patients with cancer, and potentially as a novel treatment target. In the present review, the mechanisms underlying the immunosuppressive functions of MDSCs are described, and recent researches concerning the involvement of MDSCs in the progression, prognosis, and therapies of GI cancer are reviewed. The aim of this work was to present the development of novel treatments targeting MDSCs in GI cancer in the hope of improving outcomes for patients with this condition.

Human splenic myeloid derived suppressor cells: Phenotypic and clustering analysis

Myeloid derived suppressor cells (MDSCs) can be subset into monocytic (M-), granulocytic (G-) or polymorphonuclear (PMN-), and immature (i-) or early MDSCs and have a role in many disease states. In cancer patients, the frequencies of MDSCs can positively correlate with stage, grade, and survival. Most clinical studies into MDSCs have been undertaken with peripheral blood (PB); however, in the present studies, we uniquely examined MDSCs in the spleens and PB from patients with gastrointestinal cancers. In our studies, MDSCs were rigorously subset using the following markers: Lineage (LIN) (CD3, CD19 and CD56), human leukocyte antigen (HLA)-DR, CD11b, CD14, CD15, CD33, CD34, CD45, and CD16. We observed a significantly higher frequency of PMN- and M-MDSCs in the PB of cancer patients as compared to their spleens. Expression of the T-cell suppressive enzymes arginase (ARG1) and inducible nitric oxide synthase (i-NOS) were higher on all MDSC subsets for both cancer patients PB and spleen cells as compared to MDSCs from the PB of normal donors. Similar findings for the activation markers lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), program death ligand 1 (PD-L1) and program cell death protein 1 (PD-1) were observed. Interestingly, the total MDSC cell number exported to clustering analyses was similar between all sample types; however, clustering analyses of these MDSCs, using these markers, uniquely documented novel subsets of PMN-, M- and i-MDSCs. In summary, we report a comparison of splenic MDSC frequency, subtypes, and functionality in cancer patients to their PB by clustering and cytometric analyses.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Transcription factor E2F4 is an indicator of poor prognosis and is related to immune infiltration in hepatocellular carcinoma

Background: Recent studies have shown that the transcription factor E2F4 is involved in the progression of various tumors, but its expression and influence on immune cell infiltration and biological functions are largely unknown in hepatocellular carcinoma (HCC).

Methods: The Cancer Genome Atlas (TCGA) database, the Tumor Immune Estimation Resource (TIMER) and related online tools as well as a tissue microarray (TMA) were used for analyses in our study.

Results: E2F4 expression was elevated in HCC tumor tissue compared with adjacent normal tissue at both the mRNA and protein levels. Overexpression of E2F4 was markedly related to a poor prognosis in HCC patients. In addition, positively and negatively correlated significant genes of E2F4 were identified in HCC. Pathway enrichment analyses revealed that the top 100 positively correlated significant genes of E2F4 were closely related to nuclear splicing and degradation-related pathways. Furthermore, nine hub genes correlated with E2F4 expression were validated based on a protein-protein interaction (PPI) network. It was also demonstrated that E2F4 expression was negatively correlated to immune purity and positively correlated to immune cell infiltration.

Conclusion: E2F4 could serve as a novel biomarker for HCC diagnosis and prognosis prediction.

Circulating Long and Circular Noncoding RNA as Non-Invasive Diagnostic Tools of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide, partially due to late diagnosis of the disease. Growing evidence in the field of biomarker discovery has shown the promising use of nucleic acid in the early detection of many cancers, including HCC. Here, we review data on how various long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) could be used as a diagnostic tool for HCC being differentially expressed in HCC compared to non-HCC patients. These non-coding RNAs (ncRNAs) showed high stability in the blood being present as free-circulating molecules or encapsulated into exosomes. This review reports some recent evidence on the use of lncRNAs and circRNAs as possible diagnostic biomarkers for HCC. Further, their pathophysiological mechanism in liver carcinogenesis was also described, elucidating the complex regulatory networks making these ncRNAs of particular relevance for the study of liver malignancy cancer.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Importance of myeloid derived suppressor cells in cancer from a biomarker perspective

Myeloid derived suppressor cells (MDSC) are a heterogenous population of immature myeloid cells that accumulate in tumor bearing host and migrate to lymphoid organs and tumor tissues. This process is controlled by a set of defined pro-inflammatory cytokines and chemokines, which are upregulated in malignancies. MDSC have strong immunosuppressive potential and constitute a major component of the tumor microenvironment (TME). Tumor cells take advantage of the suppressive mechanisms of MDSC to establish an immunosuppressive TME which inhibits antitumor immune responses thereby promoting cancer progression. An immunosuppressive TME acts as a significant barrier to immunotherapeutic interventions. Pre-clinical and clinical studies have demonstrated that enrichment and activation of MDSC is correlated with tumor progression, recurrence and metastasis. In this review we discuss the potential impact of MDSC on tumor progression and its role as a biomarker of prognostic significance in cancer with a special focus on hepatocellular cancer (HCC).

Myeloid-Derived Suppressor Cells: A New and Pivotal Player in Colorectal Cancer Progression

Colorectal cancer (CRC) remains a devastating human malignancy with poor prognosis. Of the various factors, immune evasion mechanisms play pivotal roles in CRC progression and impede the effects of cancer therapy. Myeloid-derived suppressor cells (MDSCs) constitute an immature population of myeloid cells that are typical during tumor progression. These cells have the ability to induce strong immunosuppressive effects within the tumor microenvironment (TME) and promote CRC development. Indeed, MDSCs have been shown to accumulate in both tumor-bearing mice and CRC patients, and may therefore become an obstacle for cancer immunotherapy. Consequently, numerous studies have focused on the characterization of MDSCs and their immunosuppressive capacity, as well as developing novel approaches to suppress MDSCs function with different approaches. Current therapeutic strategies that target MDSCs in CRC include inhibition of their recruitment and alteration of their function, alone or in combination with other therapies including chemotherapy, radiotherapy and immunotherapy. Herein, we summarize the recent roles and mechanisms of MDSCs in CRC progression. In addition, a brief review of MDSC-targeting approaches for potential CRC therapy is presented.

A prognostic risk model based on immune-related genes predicts overall survival of patients with hepatocellular carcinoma

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is one of the most common heterogeneous tumors that occurs after chronic liver diseases and hepatitis virus infection. Immune-related genes (IRGs) and their ligands regulate the homeostasis of tumor microenvironment, which is essential for the treatment of HCC and its prognosis. This study aimed to investigate the clinical value of IRGs in predicting the prognosis of HCC.

METHODS

We downloaded RNA-seq data and clinical information from TCGA database. Samples were randomly divided into training cohort and testing cohort. The "limma" R package was performed to identify differentially expressed IRGs (DEIRGs) between HCC group and normal group. Prognostic DEIRGs (PDEIRGs) were obtained by univariate Cox analysis. LASSO and multivariate Cox analysis were used, and a prognostic risk model was constructed. In order to better demonstrate the clinical value of our model in predicting overall survival rate, a nomogram was constructed. To further investigate the molecular mechanism of our model, gene set enrichment analysis (GSEA) was performed.

RESULTS

Compared with the low-risk group, the high-risk group had a significantly worse prognosis. Moreover, our prognostic risk model can accurately stratify tumor grade and TNM stage. Importantly, in our model, not only immune checkpoint genes were well predicted, but also human leucocyte antigen-I molecules were revealed. GSEA suggested that "MAPK signaling pathway," "mTOR signaling pathway," "NOD like receptor signaling pathway," "Toll like receptor signaling pathway," "VEGF signaling pathway," "WNT signaling pathway" had significant correlations with the high-risk group.

CONCLUSION

Overall, our study showed that our prognostic risk model can be used to assess prognosis of HCC, which may provide a certain basis for the survival rate of patients with HCC.

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

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

[Research on the effect of PD-L1 overexpression on CLL-1 CAR-T anti-acute myeloid leukemia]

Objective: To investigate the effects of programmed death receptor ligand 1(PD-L1)on CLL-1 CAR-T against acute myeloid leukemia(AML). Methods: In this experiment, the PD-L1 expression vector was constructed, and then the lentivirus vector was packaged by three-plasmid packaging system. THP-1 monoclonal cell lines stably expressing PD-L1 were set up. The CLL-1 CAR-T was developed by our team, as the effector cell for co-culture with the THP-1 or THP1-PDL1 cell lines, respectively. Then, the LDH was tested using the kit, the supernatant cytokine was detected by CBA, and the CLL-1 CAR-T cell proliferation was demonstrated by flow cytometry(FCM)with CSFE labeled. Results: ①The PD-L1 lentivirus vector was successfully constructed, and monoclonal cell lines of THP-1 with stable PD-L1 was set up and verified by FCM and PCR. ②The overexpression of PD-L1 inhibited CLL-1 CAR-T's ability to lyse THP-1 cells(E∶F ratio 10∶1); the killing efficiency of CLL-1 CAR-T on THP1-PDL1 cells was lower than that of THP-1 cells[(15.70±9.90)% vs(51.95 ± 2.52)%, P<0.05]. ③The overexpression of PD-L1 decrease the release of cytokine[THP1-PDL1 group vs THP-1 group: IFN-γ(115.66±3.13)pg/ml vs(1708.16 ± 26.76)pg/ml, P<0.05; IL-6(17.37±0.72)pg/ml vs(124.92±4.26)pg/ml, P<0.05; IL-10(5.69±0.13)pg/ml vs(124.12±3.02)pg/ml, P<0.05]. Additionally, the proliferation of CLL-1 CAR-T was also inhibited. Conclusion: Monoclonal cell lines of THP-1 with stable PD-L1 expression were successfully constructed, and the adverse effect of PD-L1 overexpression on CLL-1 CAR-T anti-AML was confirmed, which provided a theoretical basis for the regulation of CLL-1CAR-T through the PD-1/PD-L1 pathway.

Translational Considerations to Improve Response and Overcome Therapy Resistance in Immunotherapy for Hepatocellular Carcinoma

Over the last decade, progress in systemic therapies significantly improved the outcome of primary liver cancer. More recently, precision oncological and immunotherapeutic approaches became the focus of intense scientific and clinical research. Herein, preclinical studies showed promising results with high response rates and improvement of overall survival. However, results of phase III clinical trials revealed that only a subfraction of hepatocellular carcinoma (HCC) patients respond to therapy and display only moderate objective response rates. Further, predictive molecular characteristics are largely missing. In consequence, suitable trial design has emerged as a crucial factor for the success of a novel compound. In addition, increasing knowledge from translational studies indicate the importance of targeting the tumor immune environment to overcome resistance to immunotherapy. Thus, combination of different immunotherapies with other treatment modalities including antibodies, tyrosine kinase inhibitors, or local therapies is highly promising. However, the mechanisms of failure to respond to immunotherapy in liver cancer are still not fully understood and the modulation of the immune system and cellular tumor composition is particularly relevant in this context. Altogether, it is increasingly clear that tailoring of immunotherapy and individualized approaches are required to improve efficacy and patient outcome in liver cancer. This review provides an overview of the current knowledge as well as translational considerations to overcome therapy resistance in immunotherapy of primary liver cancer.

Myeloid-Derived Suppressor Cells in Tumors: From Mechanisms to Antigen Specificity and Microenvironmental Regulation

Among the various immunological and non-immunological tumor-promoting activities of myeloid-derived suppressor cells (MDSCs), their immunosuppressive capacity remains a key hallmark. Effort in the past decade has provided us with a clearer view of the suppressive nature of MDSCs. More suppressive pathways have been identified, and their recognized targets have been expanded from T cells and natural killer (NK) cells to other immune cells. These novel mechanisms and targets afford MDSCs versatility in suppressing both innate and adaptive immunity. On the other hand, a better understanding of the regulation of their development and function has been unveiled. This intricate regulatory network, consisting of tumor cells, stromal cells, soluble mediators, and hostile physical conditions, reveals bi-directional crosstalk between MDSCs and the tumor microenvironment. In this article, we will review available information on how MDSCs exert their immunosuppressive function and how they are regulated in the tumor milieu. As MDSCs are a well-established obstacle to anti-tumor immunity, new insights in the potential synergistic combination of MDSC-targeted therapy and immunotherapy will be discussed.