The key role of IL-6-arginase cascade for inducing dendritic cell-dependent CD4(+) T cell dysfunction in tumor-bearing mice

Targeting OXCT1-mediated ketone metabolism reprograms macrophages to promote antitumor immunity via CD8+ T cells in hepatocellular carcinoma

BACKGROUND & AIMS

The liver is the main organ of ketogenesis, while ketones are mainly metabolized in peripheral tissues via the critical enzyme 3-oxoacid CoA-transferase 1 (OXCT1). We previously found that ketolysis is reactivated in hepatocellular carcinoma (HCC) cells through OXCT1 expression to promote tumor progression; however, whether OXCT1 regulates antitumor immunity remains unclear.

METHODS

To investigate the expression pattern of OXCT1 in HCC in vivo, we conducted multiplex immunohistochemistry experiments on human HCC specimens. To explore the role of OXCT1 in mouse HCC tumor-associated macrophages (TAMs), we generated LysMcreOXCT1f/f (OXCT1 conditional knockout in macrophages) mice.

RESULTS

Here, we found that inhibiting OXCT1 expression in tumor-associated macrophages reduced CD8+ T-cell exhaustion through the succinate-H3K4me3-Arg1 axis. Initially, we found that OXCT1 was highly expressed in liver macrophages under steady state and that OXCT expression was further increased in TAMs. OXCT1 deficiency in macrophages suppressed tumor growth by reprogramming TAMs toward an antitumor phenotype, reducing CD8+ T-cell exhaustion and increasing CD8+ T-cell cytotoxicity. Mechanistically, high OXCT1 expression induced the accumulation of succinate, a byproduct of ketolysis, in TAMs, which promoted Arg1 transcription by increasing the H3K4me3 level in the Arg1 promoter. In addition, pimozide, an inhibitor of OXCT1, suppressed Arg1 expression as well as TAM polarization toward the protumor phenotype, leading to decreased CD8+ T-cell exhaustion and slower tumor growth. Finally, high expression of OXCT1 in macrophages was positively associated with poor survival in patients with HCC.

CONCLUSIONS

In conclusion, our results demonstrate that OXCT1 epigenetically suppresses antitumor immunity, suggesting that suppressing OXCT1 activity in TAMs could be an effective approach for treating liver cancer.

IMPACT AND IMPLICATIONS

The intricate metabolism of liver macrophages plays a critical role in shaping hepatocellular carcinoma progression and immune modulation. Targeting macrophage metabolism to counteract immune suppression presents a promising avenue for hepatocellular carcinoma treatment. Herein, we found that the ketogenesis gene OXCT1 was highly expressed in tumor-associated macrophages (TAMs) and promoted tumor growth by reprogramming TAMs toward a protumor phenotype. Pharmacological targeting or genetic downregulation of OXCT1 in TAMs enhances antitumor immunity and slows tumor growth. Our results suggest that suppressing OXCT1 activity in TAMs could be an effective approach for treating liver cancer.

Extracellular vesicles at the crossroad between cancer progression and immunotherapy: focus on dendritic cells

Extracellular vesicles (EVs) are nanosized heat-stable vesicles released by virtually all cells in the body, including tumor cells and tumor-infiltrating dendritic cells (DCs). By carrying molecules from originating cells, EVs work as cell-to-cell communicators in both homeostasis and cancer but may also represent valuable therapeutic and diagnostic tools. This review focuses on the role of tumor-derived EVs (TEVs) in the modulation of DC functions and on the therapeutic potential of both tumor- and DC-derived EVs in the context of immunotherapy and DC-based vaccine design. TEVs were originally characterized for their capability to transfer tumor antigens to DCs but are currently regarded as mainly immunosuppressive because of the expression of DC-inhibiting molecules such as PD-L1, HLA-G, PGE2 and others. However, TEVs may still represent a privileged system to deliver antigenic material to DCs upon appropriate engineering to reduce their immunosuppressive cargo or increase immunogenicity. DC-derived EVs are more promising than tumor-derived EVs since they expose antigen-loaded MHC, costimulatory molecules and NK cell-activating ligands in the absence of an immunosuppressive cargo. Moreover, DC-derived EVs possess several advantages as compared to cell-based drugs such as a higher antigen/MHC concentration and ease of manipulation and a lower sensitivity to immunosuppressive microenvironments. Preclinical models showed that DC-derived EVs efficiently activate tumor-specific NK and T cell responses either directly or indirectly by transferring antigens to tumor-infiltrating DCs. By contrast, however, phase I and II trials showed a limited clinical efficacy of EV-based anticancer vaccines. We discuss that the future of EV-based therapy depends on our capability to overcome major challenges such as a still incomplete understanding of their biology and pharmacokinetic and the lack of standardized methods for high-throughput isolation and purification. Despite this, EVs remain in the limelight as candidates for cancer immunotherapy which may outmatch cell-based strategies in the fullness of their time.

IL-6 promotes tumor growth through immune evasion but is dispensable for cachexia

Various cytokines have been implicated in cancer cachexia. One such cytokine is IL-6, deemed as a key cachectic factor in mice inoculated with colon carcinoma 26 (C26) cells, a widely used cancer cachexia model. Here we tested the causal role of IL-6 in cancer cachexia by knocking out the IL-6 gene in C26 cells. We found that the growth of IL-6 KO tumors was dramatically delayed. More strikingly, while IL-6 KO tumors eventually reached the similar size as wild-type tumors, cachexia still took place, despite no elevation in circulating IL-6. In addition, the knockout of leukemia inhibitory factor (LIF), another IL-6 family cytokine proposed as a cachectic factor in the model, also affected tumor growth but not cachexia. We further showed an increase in the infiltration of immune cell population in the IL-6 KO tumors compared with wild-type controls and the defective IL-6 KO tumor growth was rescued in immunodeficient mice while cachexia was not. Thus, IL-6 promotes tumor growth by facilitating immune evasion but is dispensable for cachexia.

Serum immune biomarker levels combined with hepatitis B virus infection status predict early recurrence of early-stage hepatocellular carcinoma with microvascular invasion after liver resection

INTRODUCTION

The tumor immune response plays a vital role in cancer recurrence in patients with malignancies. We aim to clarify the risk factors for early recurrence and investigate the efficacy of blood-based biomarkers to predict the risk of early recurrence in early-stage hepatocellular carcinoma (HCC) patients with microvascular invasion (MVI) after hepatectomy.

MATERIALS AND METHODS

A total of 101 cases of HCC with MVI who underwent liver resection were enrolled. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors of early recurrence. We calculated the area under the receiver operating characteristic curve to evaluate the performance of the four biomarkers identified as risk factors for early recurrence.

RESULTS

Multiple logistic regression analysis indicated that complement (C)4, cluster of differentiation (CD)4+, immunoglobulin A (IgA), and hepatitis B virus (HBV) DNA of greater than 500 IU/mL were correlated with early recurrence of HCC. The area under the curve was greater for the combination model than for the HBV DNA, CD4+, IgA, or C4 models alone.

CONCLUSION

Preoperative serum CD4+, C4, IgA, and HBV DNA levels were linked with early recurrence of early-stage HCC with MVI and the combination model was of considerable predictive value for the prognosis of HCC with MVI.

New perspectives in cancer immunotherapy: targeting IL-6 cytokine family

Chronic inflammation has been recognized as a canonical cancer hallmark. It is orchestrated by cytokines, which are master regulators of the tumor microenvironment (TME) as they represent the main communication bridge between cancer cells, the tumor stroma, and the immune system. Interleukin (IL)-6 represents a keystone cytokine in the link between inflammation and cancer. Many cytokines from the IL-6 family, which includes IL-6, oncostatin M, leukemia inhibitory factor, IL-11, IL-27, IL-31, ciliary neurotrophic factor, cardiotrophin 1, and cardiotrophin-like cytokine factor 1, have been shown to elicit tumor-promoting roles by modulating the TME, making them attractive therapeutic targets for cancer treatment.The development of immune checkpoint blockade (ICB) immunotherapies has radically changed the outcome of some cancers including melanoma, lung, and renal, although not without hurdles. However, ICB shows limited efficacy in other solid tumors. Recent reports support that chronic inflammation and IL-6 cytokine signaling are involved in resistance to immunotherapy. This review summarizes the available preclinical and clinical data regarding the implication of IL-6-related cytokines in regulating the immune TME and the response to ICB. Moreover, the potential clinical benefit of combining ICB with therapies targeting IL-6 cytokine members for cancer treatment is discussed.

The present roles and future perspectives of Interleukin-6 in biliary tract cancer

Biliary tract cancer (BTC) is a highly malignant tumor that originates from bile duct epithelium and is categorized into intrahepatic cholangiocarcinoma (iCCA), perihilar cholangiocarcinoma (pCCA), distal cholangiocarcinoma (dCCA) and gallbladder cancer (GBC) according to the anatomic location. Inflammatory cytokines generated by chronic infection led to an inflammatory microenvironment which influences the carcinogenesis of BTC. Interleukin-6 (IL-6), a multifunctional cytokine secreted by kupffer cells, tumor-associated macrophages, cancer-associated fibroblasts (CAFs) and cancer cells, plays a central role in tumorigenesis, angiogenesis, proliferation, and metastasis in BTC. Besides, IL-6 serves as a clinical biomarker for diagnosis, prognosis, and monitoring for BTC. Moreover, preclinical evidence indicates that IL-6 antibodies could sensitize tumor immune checkpoint inhibitors (ICIs) by altering the number of infiltrating immune cells and regulating the expression of immune checkpoints in the tumor microenvironment (TME). Recently, IL-6 has been shown to induce programmed death ligand 1 (PD-L1) expression through the mTOR pathway in iCCA. However, the evidence is insufficient to conclude that IL-6 antibodies could boost the immune responses and potentially overcome the resistance to ICIs for BTC. Here, we systematically review the central role of IL-6 in BTC and summarize the potential mechanisms underlying the improved efficacy of treatments combining IL-6 antibodies with ICIs in tumors. Given this, a future direction is proposed for BTC to increase ICIs sensitivity by blocking IL-6 pathways.

IL-6 is dispensable for causing cachexia in the colon carcinoma 26 model

Various cytokines have been implicated in cancer cachexia. One such cytokine is IL-6, which has been deemed a key cachectic factor in mice inoculated with the colon carcinoma 26 (C26) cells, one of the most widely used models of cancer cachexia. Here to test the causal role of IL-6 in cancer cachexia, we used CRISPR/Cas9 editing to knock out IL-6 in C26 cells. We found that growth of IL-6 KO C26 tumors was dramatically delayed. Most strikingly, while IL-6 KO tumors eventually reached the similar size as wild-type tumors, cachexia still took place, despite no elevation in circulating IL-6. We further showed an increase of immune cell populations in IL-6 KO tumors and the defective IL-6 KO tumor growth was rescued in immunodeficient mice. Thus, our results invalidated IL-6 as a necessary factor for causing cachexia in the C26 model and revealed instead its important role in regulating tumor growth via immune suppression.

Dendritic cell subsets in cancer immunity and tumor antigen sensing

Dendritic cells (DCs) exhibit a specialized antigen-presenting function and play crucial roles in both innate and adaptive immune responses. Due to their ability to cross-present tumor cell-associated antigens to naïve T cells, DCs are instrumental in the generation of specific T-cell-mediated antitumor effector responses in the control of tumor growth and tumor cell dissemination. Within an immunosuppressive tumor microenvironment, DC antitumor functions can, however, be severely impaired. In this review, we focus on the mechanisms of DC capture and activation by tumor cell antigens and the role of the tumor microenvironment in shaping DC functions, taking advantage of recent studies showing the phenotype acquisition, transcriptional state and functional programs revealed by scRNA-seq analysis. The therapeutic potential of DC-mediated tumor antigen sensing in priming antitumor immunity is also discussed.

CD8+ T cell-intrinsic IL-6 signaling promotes resistance to anti-PD-L1 immunotherapy

Although immune checkpoint inhibitors (ICIs) are established as effective cancer therapies, overcoming therapeutic resistance remains a critical challenge. Here we identify interleukin 6 (IL-6) as a correlate of poor response to atezolizumab (anti-PD-L1) in large clinical trials of advanced kidney, breast, and bladder cancers. In pre-clinical models, combined blockade of PD-L1 and the IL-6 receptor (IL6R) causes synergistic regression of large established tumors and substantially improves anti-tumor CD8⁺ cytotoxic T lymphocyte (CTL) responses compared with anti-PD-L1 alone. Circulating CTLs from cancer patients with high plasma IL-6 display a repressed functional profile based on single-cell RNA sequencing, and IL-6-STAT3 signaling inhibits classical cytotoxic differentiation of CTLs in vitro. In tumor-bearing mice, CTL-specific IL6R deficiency is sufficient to improve anti-PD-L1 activity. Thus, based on both clinical and experimental evidence, agents targeting IL-6 signaling are plausible partners for combination with ICIs in cancer patients.

Arginase-1 inhibition reduces migration ability and metastatic colonization of colon cancer cells

BACKGROUND

Arginase-1 (ARG1), a urea cycle-related enzyme, catalyzes the hydrolysis of arginine to urea and ornithine, which regulates the proliferation, differentiation, and function of various cells. However, it is unclear whether ARG1 controls the progression and malignant alterations of colon cancer.

METHODS

We established metastatic colonization mouse model and ARG1 overexpressing murine colon cancer CT26 cells to investigate whether activation of ARG1 was related to malignancy of colon cancer cells in vivo. Living cell numbers and migration ability of CT26 cells were evaluated in the presence of ARG inhibitor in vitro.

RESULTS

Inhibition of arginase activity significantly suppressed the proliferation and migration ability of CT26 murine colon cancer cells in vitro. Overexpression of ARG1 in CT26 cells reduced intracellular L-arginine levels, enhanced cell migration, and promoted epithelial-mesenchymal transition. Metastatic colonization of CT26 cells in lung and liver tissues was significantly augmented by ARG1 overexpression in vivo. ARG1 gene expression was higher in the tumor tissues of liver metastasis than those of primary tumor, and arginase inhibition suppressed the migration ability of HCT116 human colon cancer cells.

CONCLUSION

Activation of ARG1 is related to the migration ability and metastatic colonization of colon cancer cells, and blockade of this process may be a novel strategy for controlling cancer malignancy.

Overcoming resistance to oncolytic virus M1 by targeting PI3K-γ in tumor-associated myeloid cells

Oncolytic viruses (OVs) have become a category of promising anticancer immunotherapeutic agents over the last decade. However, the fact that many individuals fail to respond to OVs highlights the importance of defining the barely known immunosuppressive mechanisms that lead to treatment resistance. Here we found that the immunosuppression mediated by tumor-associated myeloid cells (TAMCs) directly quenches the antitumor effect of oncolytic virus M1 (OVM). OVM induces myeloid cells to migrate into tumors and strengthens their immunosuppressive phenotypes. Mechanically, tumor cells treated with OVM secrete interleukin-6 (IL-6) to activate the phosphatidylinositol 3-kinase (PI3K)-γ/Akt axis in TAMCs, promoting infiltration of TAMCs and aggravating their inhibition on cytotoxic CD8+ T lymphocytes. Pharmacologically targeting PI3K-γ relieves TAMC-mediated immunosuppression and enhances the efficacy of OVM. Additional treatment with immune checkpoint antibodies eradicates multiple refractory solid tumors and induces potent long-term antitumor immune memory. Our findings indicate that OVM functions as a double-edged sword in antitumor immunity and provide insights into the rationale for liberating T cell-mediated antitumor activity by abolishing TAMC-mediated immunosuppression.

Evaluation of the Tocilizumab therapy in human cancers: Latest evidence and clinical potential

Tocilizumab (Actemra®), as the first human interleukin-6 receptor (IL-6R) antagonist, has been used in treating moderate to severe active rheumatoid arthritis (RA) patients who were undertreatment with one or more disease-modifying anti-rheumatic drugs (DMARDs) and did not improve significantly. Tocilizumab also has been administrated and confirmed in several inflammatory-based diseases. Recently, tocilizumab has been prescribed to treat patients with advanced coronavirus disease (COVID-19) and is used as one of the effective drugs in reducing the increased inflammation in these patients. On the other hand, cancer treatment has been considered by researchers one of the most important challenges to human health. Regarding inflammatory-associated malignancies, it has been shown that inflammatory mediators such as interleukin-1 beta (IL-1β), IL-6, and tumour necrosis factor-alpha (TNF-α) may play a role in tumorigenesis, thus targeting these cytokines as evidence suggested can be useful in the treatment of these types of cancers. This review summarized the role of the IL-6/IL-6R axis in inflammation-based cancers and discussed the effectiveness and challenges of treating cancer with tocilizumab.

Targeting arginase-1 exerts antitumor effects in multiple myeloma and mitigates bortezomib-induced cardiotoxicity

Multiple myeloma (MM) remains an incurable malignancy of plasma cells despite constantly evolving therapeutic approaches including various types of immunotherapy. Increased arginase activity has been associated with potent suppression of T-cell immune responses in different types of cancer. Here, we investigated the role of arginase 1 (ARG1) in Vκ*MYC model of MM in mice. ARG1 expression in myeloid cells correlated with tumor progression and was accompanied by a systemic drop in ʟ-arginine levels. In MM-bearing mice antigen-induced proliferation of adoptively transferred T-cells was strongly suppressed and T-cell proliferation was restored by pharmacological arginase inhibition. Progression of Vκ*MYC tumors was significantly delayed in mice with myeloid-specific ARG1 deletion. Arginase inhibition effectively inhibited tumor progression although it failed to augment anti-myeloma effects of bortezomib. However, arginase inhibitor completely prevented development of bortezomib-induced cardiotoxicity in mice. Altogether, these findings indicate that arginase inhibitors could be further tested as a complementary strategy in multiple myeloma to mitigate adverse cardiac events without compromising antitumor efficacy of proteasome inhibitors.

Interleukin-6 and indoleamine-2,3-dioxygenase as potential adjuvant targets for Papillomavirus-related tumors immunotherapy

High-risk Human papillomavirus (HPV) infections represent an important public health issue. Nearly all cervical malignancies are associated with HPV, and a range of other female and male cancers, such as anogenital and oropharyngeal. Aiming to treat HPV-related tumors, our group developed vaccines based on the genetic fusion of the HSV-1 glycoprotein D (gD) with the HPV-16 E7 oncoprotein (gDE7 vaccines). Despite the promising antitumor results reached by gDE7 vaccines in mice, combined therapies may increase the therapeutic effects by improving antitumor responses and halting immune suppressive mechanisms elicited by tumor cells. Considering cancer immunosuppressive mechanisms, indoleamine-2,3-dioxygenase (IDO) enzyme and interleukin-6 (IL-6) stand out in HPV-related tumors. Since IL-6 sustained the constitutive IDO expression, here we evaluated the therapeutic outcomes achieved by the combination of active immunotherapy based on a gDE7 protein-based vaccine with adjuvant treatments involving blocking IDO, either by use of IDO inhibitors or IL-6 knockout mice. C57BL/6 wild-type (WT) and transgenic IL-6-/- mice were engrafted with HPV16-E6/E7-expressing TC-1 cells and treated with 1-methyl-tryptophan isoforms (D-1MT and DL-1MT), capable to inhibit IDO. In vitro, the 1MT isoforms reduced IL-6 gene expression and IL-6 secretion in TC-1 cells. In vivo, the multi-targeted treatment improved the antitumor efficacy of the gDE7-based protein vaccine. Although the gDE7 immunization achieves partial tumor mass control in combination with D-1MT or DL-1MT in WT mice or when administered in IL-6-/- mice, the combination of gDE7 and 1MT in IL-6-/- mice further enhanced the antitumor effects, reaching total tumor rejection. The outcome of the combined therapy was associated with an increased frequency of activated dendritic cells and decreased frequencies of intratumoral polymorphonuclear myeloid-derived suppressor cells and T regulatory cells. In conclusion, the present study demonstrated that IL-6 and IDO negatively contribute to the activation of immune cells, particularly dendritic cells, reducing gDE7 vaccine-induced protective immune responses and, therefore, opening perspectives for the use of combined strategies based on inhibition of IL-6 and IDO as immunometabolic adjuvants for immunotherapies against HPV-related tumors.

Chidamide plus Tyrosine Kinase Inhibitor Remodel the Tumor Immune Microenvironment and Reduce Tumor Progression When Combined with Immune Checkpoint Inhibitor in Naïve and Anti-PD-1 Resistant CT26-Bearing Mice

Combined inhibition of vascular endothelial growth factor receptor (VEGFR) and the programmed cell death protein 1 (PD-1) pathways has shown efficacy in multiple cancers; however, the clinical outcomes show limited benefits and the unmet clinical needs still remain and require improvement in efficacy. Using murine colon carcinoma (CT26) allograft models, we examined the efficacy and elucidated novel tumor microenvironment (TME) remodeling mechanisms underlying the combination of chidamide (a benzamide-based class l histone deacetylase inhibitor; brand name in Taiwan, Kepida®) with VEGF receptor tyrosine kinase inhibitor (TKIs; cabozantinib/regorafenib, etc.) and immune checkpoint inhibitors (ICIs; anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies). The TME was assessed using flow cytometry and RNA-sequencing to determine the novel mechanisms and their correlation with therapeutic effects in mice with significant treatment response. Compared with ICI alone or cabozantinib/regorafenib + ICI, combination of chidamide + cabozantinib/regorafenib + ICI increased the tumor response and survival benefits. In particular, treatment of CT26-bearing mice with chidamide + regorafenib + anti-PD-1 antibody showed a better objective response rate (ORR) and overall survival (OS). Similar results were observed in anti-PD-1 treatment-resistant mice. After treatment with this optimal combination, in the TME, RNA-sequencing revealed that downregulated mRNAs were correlated with leukocyte migration, cell chemotaxis, and macrophage gene sets, and flow cytometry analysis showed that the cell numbers of myeloid-derived polymorphonuclear suppressor cells and tumor-associated macrophages were decreased. Accordingly, chidamide + regorafenib + anti-PD-1 antibody combination therapy could trigger a novel TME remodeling mechanism by attenuating immunosuppressive cells, and restoring T-cell activation to enhance ORR and OS. Our studies also showed that the addition of Chidamide to the regorafenib + anti-PD-1 Ab combination could induce a durable tumor-specific response by attenuating immune suppression in the TME. In addition, this result suggests that TME remodeling, mediated by epigenetic immunomodulator combined with TKI and ICI, would be more advantageous for achieving a high objective response rate, when compared to TKI plus ICI or ICI alone, and maintaining long-lasting antitumor activity.

Combination of pioglitazone and dendritic cell to optimize efficacy of immune cell therapy in CT26 tumor models

Introduction

The maturation faith of dendritic cells is restrained by the inflammatory environment and cytokines, such as interleukin-6 and its downstream component. Therefore, introducing the suitable antigen to dendritic cells is crucial. However, reducing the severity of the suppressive tumor microenvironment is indispensable. The present study examined the combination therapy of lymphocyte antigen 6 family member E (LY6E) pulsed mature dendritic cells (LPMDCs) and pioglitazone against colorectal cancer (CRC) to elevate the effectiveness of cancer treatment through probable role of pioglitazone on inhibiting IL-6/STAT3 pathway.

Methods

Dendritic cells were generated from murine bone marrow and were pulsed with lymphocyte antigen 6 family member E peptide to assess antigen-specific T-cell proliferation and cytotoxicity assay with Annexin/PI. The effect of pioglitazone on interleukin (IL)-6/STAT3 was evaluated in vitro by real-time polymerase chain reaction (PCR). Afterward, the CRC model was established by subcutaneous injection of CT26, mouse colon carcinoma cell line, in female mice. After treatment, tumor, spleen, and lymph nodes samples were removed for histopathological, ELISA, and real-time PCR analysis.

Results

In vitro results revealed the potential of lysate-pulsed dendritic cells in the proliferation of double-positive CD3-8 splenocytes and inducing immunogenic cell death responses, whereas pioglitazone declined the expression of IL-6/STAT3 in colorectal cell lines. In animal models, the recipient of LPMDCs combined with pioglitazone demonstrated high tumor-infiltrating lymphocytes. Elevating the IL-12 and interferon-gamma (IFN-γ) levels and prolonged survival in lysate-pulsed dendritic cell and combination groups were observed.

Conclusion

Pioglitazone could efficiently ameliorate the immunosuppressive feature of the tumor microenvironment, mainly through IL-6. Accordingly, applying this drug combined with LPMDCs provoked substantial CD8 positive responses in tumor-challenged animal models.

ARG1 as a promising biomarker for sepsis diagnosis and prognosis: evidence from WGCNA and PPI network

Background

Sepsis is a life-threatening multi-organ dysfunction caused by the dysregulated host response to infection. Sepsis remains a major global concern with high mortality and morbidity, while management of sepsis patients relies heavily on early recognition and rapid stratification. This study aims to identify the crucial genes and biomarkers for sepsis which could guide clinicians to make rapid diagnosis and prognostication.

Methods

Preliminary analysis of multiple global datasets, including 170 samples from patients with sepsis and 110 healthy control samples, revealed common differentially expressed genes (DEGs) in peripheral blood of patients with sepsis. After Gene Oncology (GO) and pathway analysis, the Weighted Gene Correlation Network Analysis (WGCNA) was used to screen for genes most related with clinical diagnosis. Also, the Protein-Protein Interaction Network (PPI Network) was constructed based on the DEGs and the hub genes were found. The results of WGCNA and PPI network were compared and one shared gene was discovered. Then more datasets of 728 experimental samples and 355 control samples were used to prove the diagnostic and prognostic value of this gene. Last, we used real-time PCR to confirm the bioinformatic results.

Results

Four hundred forty-four common differentially expressed genes in the blood of sepsis patients from different ethnicities were identified. Fifteen genes most related with clinical diagnosis were found by WGCNA, and 24 hub genes with most node degrees were identified by PPI network. ARG1 turned out to be the unique overlapped gene. Further analysis using more datasets showed that ARG1 was not only sharply up-regulated in sepsis than in healthy controls, but also significantly high-expressed in septic shock than in non-septic shock, significantly high-expressed in severe or lethal sepsis than in uncomplicated sepsis, and significantly high-expressed in non-responders than in responders upon early treatment. These all demonstrate the performance of ARG1 as a key biomarker. Last, the up-regulation of ARG1 in the blood was confirmed experimentally.

Conclusions

We identified crucial genes that may play significant roles in sepsis by WGCNA and PPI network. ARG1 was the only overlapped gene in both results and could be used to make an accurate diagnosis, discriminate the severity and predict the treatment response of sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41065-022-00240-1.

Bulk and Single-Cell Profiling of Breast Tumors Identifies TREM-1 as a Dominant Immune Suppressive Marker Associated With Poor Outcomes

Background

Triggering receptor expressed on myeloid cells (TREM)-1 is a key mediator of innate immunity previously associated with the severity of inflammatory disorders, and more recently, the inferior survival of lung and liver cancer patients. Here, we investigated the prognostic impact and immunological correlates of TREM1 expression in breast tumors.

Methods

Breast tumor microarray and RNAseq expression profiles (n=4,364 tumors) were analyzed for associations between gene expression, tumor immune subtypes, distant metastasis-free survival (DMFS) and clinical response to neoadjuvant chemotherapy (NAC). Single-cell (sc)RNAseq was performed using the 10X Genomics platform. Statistical associations were assessed by logistic regression, Cox regression, Kaplan-Meier analysis, Spearman correlation, Student’s t-test and Chi-square test.

Results

In pre-treatment biopsies, TREM1 and known TREM-1 inducible cytokines (IL1B, IL8) were discovered by a statistical ranking procedure as top genes for which high expression was associated with reduced response to NAC, but only in the context of immunologically “hot” tumors otherwise associated with a high NAC response rate. In surgical specimens, TREM1 expression varied among tumor molecular subtypes, with highest expression in the more aggressive subtypes (Basal-like, HER2-E). High TREM1 significantly and reproducibly associated with inferior distant metastasis-free survival (DMFS), independent of conventional prognostic markers. Notably, the association between high TREM1 and inferior DMFS was most prominent in the subset of immunogenic tumors that exhibited the immunologically hot phenotype and otherwise associated with superior DMFS. Further observations from bulk and single-cell RNAseq analyses indicated that TREM1 expression was significantly enriched in polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and M2-like macrophages, and correlated with downstream transcriptional targets of TREM-1 (IL8, IL-1B, IL6, MCP-1, SPP1, IL1RN, INHBA) which have been previously associated with pro-tumorigenic and immunosuppressive functions.

Conclusions

Together, these findings indicate that increased TREM1 expression is prognostic of inferior breast cancer outcomes and may contribute to myeloid-mediated breast cancer progression and immune suppression.

Longitudinal Metabolomics Reveals Ornithine Cycle Dysregulation Correlates With Inflammation and Coagulation in COVID-19 Severe Patients

COVID-19 is a severe disease in humans, as highlighted by the current global pandemic. Several studies about the metabolome of COVID-19 patients have revealed metabolic disorders and some potential diagnostic markers during disease progression. However, the longitudinal changes of metabolomics in COVID-19 patients, especially their association with disease progression, are still unclear. Here, we systematically analyzed the dynamic changes of the serum metabolome of COVID-19 patients, demonstrating that most of the metabolites did not recover by 1-3 days before discharge. A prominent signature in COVID-19 patients comprised metabolites of amino acids, peptides, and analogs, involving nine essential amino acids, 10 dipeptides, and four N-acetylated amino acids. The levels of 12 metabolites in amino acid metabolism, especially three metabolites of the ornithine cycle, were significantly higher in severe patients than in mild ones, mainly on days 1-3 or 4-6 since onset. Integrating blood metabolomic, biochemical, and cytokine data, we uncovered a highly correlated network, including 6 cytokines, 13 biochemical parameters, and 49 metabolites. Significantly, five ornithine cycle-related metabolites (ornithine, N-acetylornithine, 3-amino-2-piperidone, aspartic acid, and asparagine) highly correlated with "cytokine storms" and coagulation index. We discovered that the ornithine cycle dysregulation significantly correlated with inflammation and coagulation in severe patients, which may be a potential mechanism of COVID-19 pathogenicity. Our study provided a valuable resource for detailed exploration of metabolic factors in COVID-19 patients, guiding metabolic recovery, understanding the pathogenic mechanisms, and creating drugs against SARS-CoV-2 infection.

Tumor NLRP3-Derived IL-1β Drives the IL-6/STAT3 Axis Resulting in Sustained MDSC-Mediated Immunosuppression

Tumors evade the immune system by inducing inflammation. In melanoma, tumor-derived IL-1β drives inflammation and the expansion of highly immunosuppressive myeloid-derived suppressor cells (MDSCs). Similar in many tumors, melanoma is also linked to the downstream IL-6/STAT3 axis. In this study, we observed that both recombinant and tumor-derived IL-1β specifically induce pSTAT3(Y705), creating a tumor-autoinflammatory loop, which amplifies IL-6 signaling in the human melanoma cell line 1205Lu. To disrupt IL-1β/IL-6/STAT3 axis, we suppressed IL-1β-mediated inflammation by inhibiting the NOD-like receptor protein 3 (NLRP3) using OLT1177, a safe-in-humans specific NLRP3 oral inhibitor. In vivo, using B16F10 melanoma, OLT1177 effectively reduced tumor progression (p< 0.01); in primary tumors, OLT1177 decreased pSTAT3(Y705) by 82% (p<0.01) and II6 expression by 53% (p<0.05). Disruption of tumor-derived NLRP3, either pharmacologically or genetically, reduced STAT3 signaling in bone marrow cells. In PMN-MDSCs isolated from tumor-bearing mice treated with OLT1177, we observed significant reductions in immunosuppressive genes such as Pdcd1l1, Arg1, Il10 and Tgfb1. In conclusion, the data presented here show that the inhibition of NLRP3 reduces IL-1β induction of pSTAT3(Y705) preventing expression of immunosuppressive genes as well as activity in PMN-MDSCs.

The roles of tumor-derived exosomes in altered differentiation, maturation and function of dendritic cells

Tumor-derived exosomes (TDEs) have been shown to impede anti-tumor immune responses via their immunosuppressive cargo. Since dendritic cells (DCs) are the key mediators of priming and maintenance of T cell-mediated responses; thus it is logical that the exosomes released by tumor cells can exert a dominant influence on DCs biology. This paper intends to provide a mechanistic insight into the TDEs-mediated DCs abnormalities in the tumor context. More importantly, we discuss extensively how tumor exosomes induce subversion of DCs differentiation, maturation and function in separate sections. We also briefly describe the importance of TDEs at therapeutic level to help guide future treatment options, in particular DC-based vaccination strategy, and review advances in the design and discovery of exosome inhibitors. Understanding the exosomal content and the pathways by which TDEs are responsible for immune evasion may help to revise treatment rationales and devise novel therapeutic approaches to overcome the hurdles in cancer treatment.

Cutaneous Squamous Cell Carcinoma Development Is Associated with a Temporal Infiltration of ILC1 and NK Cells with Immune Dysfunctions

NK cells and tissue-resident innate lymphoid cells (ILCs) are innate effectors found in the skin. To investigate their temporal dynamics and specific functions throughout the development of cutaneous squamous cell carcinoma (cSCC), we combined transcriptomic and immunophenotyping analyses in mouse and human cSCCs. We identified an infiltration of NK cells and ILC1s as well as the presence of a few ILC3s. Adoptive transfer of NK cells in NK cell‒ and ILC-deficient Nfil3^-/- mice revealed a role for NK cells in early control of cSCC. During tumor progression, we identified a population skewing with the infiltration of atypical ILC1 secreting inflammatory cytokines but reduced levels of IFN-γ at the papilloma stage. NK cells and ILC1s were functionally impaired, with reduced cytotoxicity and IFN-γ secretion associated with the downregulation of activating receptors. They also showed a high degree of heterogeneity in mouse and human cSCCs with the expression of several markers of exhaustion, including TIGIT on NK cells and PD-1 and TIM-3 on ILC1s. Our data show an enrichment in inflammatory ILC1 at the precancerous stage together with impaired antitumor functions in NK cells and ILC1 that could contribute to the development of cSCC and thus suggest that future immunotherapies should take both ILC populations into account.

Metabolic Regulation of Immune Responses to Mycobacterium tuberculosis: A Spotlight on L-Arginine and L-Tryptophan Metabolism

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a leading cause of death worldwide. Despite decades of research, there is still much to be uncovered regarding the immune response to Mtb infection. Here, we summarize the current knowledge on anti-Mtb immunity, with a spotlight on immune cell amino acid metabolism. Specifically, we discuss L-arginine and L-tryptophan, focusing on their requirements, regulatory roles, and potential use as adjunctive therapy in TB patients. By continuing to uncover the immune cell contribution during Mtb infection and how amino acid utilization regulates their functions, it is anticipated that novel host-directed therapies may be developed and/or refined, helping to eradicate TB.

Toll-Like Receptor 2-Tpl2-Dependent ERK Signaling Drives Inverse Interleukin 12 Regulation in Dendritic Cells and Macrophages

This study investigated responses to Toll-like receptor 2 (TLR2)-driven extracellular signal-related kinase (ERK) signaling in dendritic cells (DCs) versus macrophages. TLR2 signaling was induced with Pam₃Cys-Ser-Lys₄, and the role of ERK signaling was interrogated pharmacologically with MEK1/2 inhibitor U0126 or genetically with bone marrow-derived macrophages or DCs from Tpl2^-/- mice. We assessed cytokine production via enzyme-linked immunosorbent assay (ELISA) or V-Plex, and mRNA levels were assessed via reverse transcriptase quantitative PCR (qRT-PCR). In macrophages, blockade of ERK signaling by pharmacologic or genetic approaches inhibited interleukin 10 (IL-10) expression and increased expression of the p40 subunit shared by IL-12 and IL-23 (IL-12/23p40). In DCs, blockade of ERK signaling similarly inhibited IL-10 expression but decreased IL-12/23p40 expression, which is opposite to the effect of ERK signaling blockade on IL-12/23p40 in macrophages. This difference in IL-12/23p40 regulation correlated with the differential expression of transcription factors cFos and IRF1, which are known to regulate IL-12 family members, including IL-12 and IL-23. Thus, the impact of ERK signaling in response to TLR2 stimulation differs between macrophages and DCs, potentially regulating their distinctive functions in the immune system. ERK-mediated suppression of IL-12/23p40 in macrophages may prevent excessive inflammation and associated tissue damage following TLR2-stimulation, while ERK-mediated induction of IL-12/23p40 in DCs may promote priming of T helper 1 (Th1) responses. A greater understanding of the role that ERK signaling plays in different immune cell types may inform the development of host-directed therapy and optimal adjuvanticity for a number of infectious pathogens.

IL-6 as a major regulator of MDSC activity and possible target for cancer immunotherapy

Myeloid-derived suppressor cells (MDSC) are generated during tumor progression and suppress the anti-tumor functions of T and natural killer (NK) cells. Their enrichment is associated with a bad prognosis and a worse outcome of immunotherapy in cancer patients. The cytokine interleukin (IL)-6 was found to be a crucial regulator of MDSC accumulation and activation as well as a factor, stimulating tumor cell proliferation, survival, invasiveness and metastasis. Accordingly, IL-6 can serve as a negative prognostic marker in cancer. On the other hand, this cytokine is also involved in T cell activation. This review discusses the pleiotropic effects of IL-6 on immune cell populations that are critical for tumor development, such as MDSC and T cells, and summarizes the data on targeting IL-6 or IL-6 receptor (IL-6R) for tumor immunotherapy to block MDSC-mediated immunosuppression in cancer patients.

Immunotherapy in Myeloproliferative Diseases

Myeloproliferative diseases, including myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS), are driven by genetic abnormalities and increased inflammatory signaling and are at high risk to transform into acute myeloid leukemia (AML). Myeloid-derived suppressor cells were reported to enhance leukemia immune escape by suppressing an effective anti-tumor immune response. MPNs are a potentially immunogenic disease as shown by their response to interferon-α treatment and allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Novel immunotherapeutic approaches such as immune checkpoint inhibition, tumor vaccination, or cellular therapies using target-specific lymphocytes have so far not shown strong therapeutic efficacy. Potential reasons could be the pro-inflammatory and immunosuppressive microenvironment in the bone marrow of patients with MPN, driving tumor immune escape. In this review, we discuss the biology of MPNs with respect to the pro-inflammatory milieu in the bone marrow (BM) and potential immunotherapeutic approaches.

STAT3/SOCS3 axis contributes to the outcome of salmonid whirling disease

There are differences in disease susceptibility to whirling disease (WD) among strains of rainbow trout. The North American strain Trout Lodge (TL) is highly susceptible, whereas the German Hofer (HO) strain is more resistant. The suppressor of cytokine signaling (SOCS) proteins are key in inhibiting cytokine signaling. Their role in modulating the immune response against whirling disease is not completely clear. This study aimed at investigating the transcriptional response of SOCS1 and SOCS3 genes to Myxobolus cerebralis along with that of several upstream regulators and immune response genes. M. cerebralis induced the expression of SOCS1, the IL-6-dependent SOCS3, the anti-inflammatory cytokine IL-10 and the Treg associated transcription factor FOXP3 in TL fish at multiple time points, which likely caused a restricted STAT1 and STAT3 activity affecting the Th17/Treg17 balance. The expression of SOCS1 and the IL-6-dependent SOCS3 was induced constraining the activation of STAT1 and STAT3 in TL fish, thereby causing Th17/Treg17 imbalance and leaving the fish unable to establish a protective immune response against M. cerebralis or control inflammatory reactions increasing susceptibility to WD. Conversely, in HO fish, the expression of SOCS1 and SOCS3 was restrained, whereas the expression of STAT1 and IL-23-mediated STAT3 was induced potentially enabling more controlled immune responses, accelerating parasite clearance and elevating resistance. The induced expression of STAT1 and IL-23-mediated STAT3 likely maintained a successful Th17/Treg17 balance and enabled fish to promote effective immune responses favouring resistance against WD. The results provide insights into the role of SOCS1 and SOCS3 in regulating the activation and magnitude of host immunity in rainbow trout, which may help us understand the mechanisms that underlie the variation in resistance to WD.

Discovery and Pharmacokinetics of Sulfamides and Guanidines as Potent Human Arginase 1 Inhibitors

We designed and synthesized a series of arginase inhibitors as derivatives of the well-known 2-(S)-amino-6-boronohexanoic acid (ABH) with basic and neutral side chains in the α-position relative to the amino acid group. In an effort to improve the pharmacokinetic profile of literature examples and retain potent enzymatic activity, sulfamido moieties were introduced to generate hydrogen bond interaction with the aspartic acid residue in the arginase active site. The compounds with basic guanidine-containing side chains were even more potent arginase inhibitors. Both groups of compounds, as designed, demonstrated low clearance in their pharmacokinetic profile. The most active inhibitor 15aa showed high nanomolar potency with IC50 = 32 nM toward human arginase 1 and demonstrated low clearance (4.2 mL/min/kg), long t 1/2, and moderate volume of distribution in rat pharmacokinetic studies.

Carbohydrate and Amino Acid Metabolism as Hallmarks for Innate Immune Cell Activation and Function

Immune activation is now understood to be fundamentally linked to intrinsic and/or extrinsic metabolic processes which are essential for immune cells to survive, proliferate, and perform their effector functions. Moreover, disruption or dysregulation of these pathways can result in detrimental outcomes and underly a number of pathologies in both communicable and non-communicable diseases. In this review, we discuss how the metabolism of carbohydrates and amino acids in particular can modulate innate immunity and how perturbations in these pathways can result in failure of these immune cells to properly function or induce unfavorable phenotypes.

Structural insights into human Arginase-1 pH dependence and its inhibition by the small molecule inhibitor CB-1158

Arginase-1 is a manganese-dependent metalloenzyme that catalyzes the hydrolysis of L-arginine into L-ornithine and urea. Arginase-1 is abundantly expressed by tumor-infiltrating myeloid cells that promote tumor immunosuppression, which is relieved by inhibition of Arginase-1. We have characterized the potencies of the Arginase-1 reference inhibitors (2S)-2-amino-6-boronohexanoic acid (ABH) and N ^ω-hydroxy-nor-L-arginine (nor-NOHA), and studied their pH-dependence and binding kinetics. To gain a better understanding of the structural changes underlying the high pH optimum of Arginase-1 and its pH-dependent inhibition, we determined the crystal structure of the human Arginase-1/ABH complex at pH 7.0 and 9.0. These structures revealed that at increased pH, the manganese cluster assumes a more symmetrical coordination structure, which presumably contributes to its increase in catalytic activity. Furthermore, we show that binding of ABH involves the presence of a sodium ion close to the manganese cluster. We also studied the investigational new drug CB-1158 (INCB001158). This inhibitor has a low-nanomolar potency at pH 7.4 and increases the thermal stability of Arginase-1 more than ABH and nor-NOHA. Moreover, CB-1158 displays slow association and dissociation kinetics at both pH 9.5 and 7.4, as indicated by surface plasmon resonance. The potent character of CB-1158 is presumably due to its increased rigidity compared to ABH as well as the formation of an additional hydrogen-bond network as observed by resolution of the Arginase-1/CB-1158 crystal structure.

Functional polarization of macrophages of rats with progesterone-induced obesity treated with melanin from the Antarctic yeast Nadsoniella nigra

Progesterone-induced obesity develops in women who use this drug for contraception and the menopause treatment, though its mechanisms remain poorly understood. We studied functional M1 and M2 polarizations of the abdominal cavity macrophages of rats with progesterone induced obesity during 28 days of administration. The effect of melanin from the Antarctic yeast Nadsoniella nigra (Chaetothyriales, Herpotrichiellaceae, Nadsoniella Issatsch, 1914) was investigated. The NO level was determined by the accumulation of nitrites, ROS level was estimated by the NBT-test, arginase activity was assayed by the reaction of L-arginine hydrolysis. The body weights of rats administrated progesterone increased by 27% and continued to increase one month after withdrawal of progesterone (55% higher than control). Melanin prevents the weight gain when administered during one month after progesterone withdrawal. The NO production by peritoneal macrophages of obese animals intensified by 31% indicating their polarization towards pro-inflammatory M1 type. Production of ROS did not change. A 14% increase in arginase activity was observed, indicating the inhibition of M2 (anti-inflammatory) polarization. In the progesterone withdrawal group all these rates significantly decreased, indicating a reduction in the functional activity of peritoneal macrophages’. Melanin decreased the NO and ROS production by 60% and 18% respectively in comparison with the progesterone group and unexpectedly reduced arginase activity. Our data provide evidence of the spread of inflammation in response to progesterone-induced obesity. Peritoneal macrophages are involved in the inflammation in obesity, undergoing polarization towards the pro-inflammatory phenotype. The long-term consequences of such inflammation include the continuation of weight gain and likely the development of systemic inflammation associated with the exhaustion of the functional capacity of peritoneal cavity macrophages. Melanin has an anti-obesity effect and exhibits anti-inflammatory properties preventing progesterone-induced weight gain and macrophage M1 polarization. This requires detailed elucidation and can be valuable in designing countermeasures to prevent obesity outcomes.

The potential therapeutic effect of NG-hydroxy-nor-L-arginine in 7,12-dimethylbenz(a)anthracene-induced breast cancer in rats

Advances in our understanding of the metabolism and molecular functions of arginine and their alterations in cancer have led to resurgence in the interest of targeting arginine catabolism as an anticancer strategy. Therefore, arginase inhibitors have been proposed as a way to treat cancer. In this study, the anti-tumor potential of the arginase inhibition by N^G-hydroxy-nor-L-arginine (nor-NOHA) (3 mg/kg/day, i.p.), administered for 5 weeks (parallel tumors development, every 3th day) against 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis in rats has been investigated. Treatment by nor-NOHA has obvious inhibition effects on development of carcinogenesis in rats was shown. That was seen in downregulation of rats' tumors size and number, mortality rate, in stopped alteration of tissue histopathology, in decrease of polyamines, NO and MDA (malondialdeide) concentrations (in blood). Results have shown arginase and NO-synthase can cooperate to restrain quantities of polyamines and NO for cancer progression. The results obtained can serve as a base to use this model for determination of productive, noncytotoxic antitumor and immune modulating concentration of anticancer agents. Perspectives of targeting arginase and NOS in cancer management can ground application in clinical medicine.

IL6 Modulates the Immune Status of the Tumor Microenvironment to Facilitate Metastatic Colonization of Colorectal Cancer Cells

It is unknown as to how liver metastases are correlated with host immune status in colorectal cancer. In this study, we found that IL6, a proinflammatory cytokine produced in tumor-bearing states, promoted the metastatic colonization of colon cancer cells in association with dysfunctional antitumor immunity. In IL6-deficient mice, metastatic colonization of CT26 cells in the liver was reduced, and the antitumor effector function of CD8⁺ T cells, as well as IL12 production by CD11c⁺ dendritic cells, were augmented in vivo IL6-deficient mice exhibited enhanced IFN-AR1-mediated type I interferon signaling, which upregulated PD-L1 and MHC class I expression on CT26 cells. In vivo injection of anti-PD-L1 effectively suppressed the metastatic colonization of CT26 cells in Il6 ^-/- but not in Il6 ^+/+ mice. Finally, we confirmed that colorectal cancer patients with low IL6 expression in their primary tumors showed prolonged disease-free survival. These findings suggest that IL6 may be a promising target for the treatment of metastasis in colorectal cancers by improving host immunity.

Small extracellular vesicles containing arginase-1 suppress T-cell responses and promote tumor growth in ovarian carcinoma

Tumor-driven immune suppression is a major barrier to successful immunotherapy in ovarian carcinomas (OvCa). Among various mechanisms responsible for immune suppression, arginase-1 (ARG1)-carrying small extracellular vesicles (EVs) emerge as important contributors to tumor growth and tumor escape from the host immune system. Here, we report that small EVs found in the ascites and plasma of OvCa patients contain ARG1. EVs suppress proliferation of CD4⁺ and CD8⁺ T-cells in vitro and in vivo in OvCa mouse models. In mice, ARG1-containing EVs are transported to draining lymph nodes, taken up by dendritic cells and inhibit antigen-specific T-cell proliferation. Increased expression of ARG1 in mouse OvCa cells is associated with accelerated tumor progression that can be blocked by an arginase inhibitor. Altogether, our studies show that tumor cells use EVs as vehicles to carry over long distances and deliver to immune cells a metabolic checkpoint molecule – ARG1, mitigating anti-tumor immune responses.

Cancer cells employ a variety of ways to escape the immune system. Here, the authors show that ovarian cancer cells produce small extracellular vescicles containing arginase 1 that are taken up by dendritic cells in the draining lymph nodes, resulting in inhibition of antigen-specific T-cell proliferation.

Immunosurveillance of cancer cell stress

Cancer development is tightly controlled by effector immune responses that recognize and eliminate malignantly transformed cells. Nonetheless, certain immune subsets, such as tumor-associated macrophages, have been described to promote tumor growth, unraveling a double-edge role of the immune system in cancer. Cell stress can modulate the crosstalk between immune cells and tumor cells, reshaping tumor immunogenicity and/or immune function and phenotype. Infiltrating immune cells are exposed to the challenging conditions typically present in the tumor microenvironment. In return, the myriad of signaling pathways activated in response to stress conditions may tip the balance toward stimulation of antitumor responses or immune-mediated tumor progression. Here, we explore how distinct situations of cellular stress influence innate and adaptive immunity and the consequent impact on cancer establishment and progression.

Elective Nodal Irradiation Attenuates the Combinatorial Efficacy of Stereotactic Radiation Therapy and Immunotherapy

Purpose: In the proper context, radiotherapy can promote antitumor immunity. It is unknown if elective nodal irradiation (ENI), a strategy that irradiates tumor-associated draining lymph nodes (DLN), affects adaptive immune responses and combinatorial efficacy of radiotherapy with immune checkpoint blockade (ICB).Experimental Design: We developed a preclinical model to compare stereotactic radiotherapy (Tumor RT) with or without ENI to examine immunologic differences between radiotherapy techniques that spare or irradiate the DLN.Results: Tumor RT was associated with upregulation of an intratumoral T-cell chemoattractant chemokine signature (CXCR3, CCR5-related) that resulted in robust infiltration of antigen-specific CD8⁺ effector T cells as well as FoxP3⁺ regulatory T cells (Tregs). The addition of ENI attenuated chemokine expression, restrained immune infiltration, and adversely affected survival when combined with ICB, especially with anti-CLTA4 therapy. The combination of stereotactic radiotherapy and ICB led to long-term survival in a subset of mice and was associated with favorable CD8 effector-to-Treg ratios and increased intratumoral density of antigen-specific CD8⁺ T cells. Although radiotherapy technique (Tumor RT vs. ENI) affected initial tumor control and survival, the ability to reject tumor upon rechallenge was partially dependent upon the mechanism of action of ICB; as radiotherapy/anti-CTLA4 was superior to radiotherapy/anti-PD-1.Conclusions: Our results highlight that irradiation of the DLN restrains adaptive immune responses through altered chemokine expression and CD8⁺ T-cell trafficking. These data have implications for combining radiotherapy and ICB, long-term survival, and induction of immunologic memory. Clinically, the immunomodulatory effect of the radiotherapy strategy should be considered when combining stereotactic radiotherapy with immunotherapy. Clin Cancer Res; 24(20); 5058-71. ©2018 AACR.

Nitric Oxide Production by Myeloid-Derived Suppressor Cells Plays a Role in Impairing Fc Receptor-Mediated Natural Killer Cell Function

Purpose: mAbs are used to treat solid and hematologic malignancies and work in part through Fc receptors (FcRs) on natural killer cells (NK). However, FcR-mediated functions of NK cells from patients with cancer are significantly impaired. Identifying the mechanisms of this dysfunction and impaired response to mAb therapy could lead to combination therapies and enhance mAb therapy.Experimental Design: Cocultures of autologous NK cells and MDSC from patients with cancer were used to study the effect of myeloid-derived suppressor cells (MDSCs) on NK-cell FcR-mediated functions including antibody-dependent cellular cytotoxicity, cytokine production, and signal transduction in vitro Mouse breast cancer models were utilized to study the effect of MDSCs on antibody therapy in vivo and test the efficacy of combination therapies including a mAb and an MDSC-targeting agent.Results: MDSCs from patients with cancer were found to significantly inhibit NK-cell FcR-mediated functions including antibody-dependent cellular cytotoxicity, cytokine production, and signal transduction in a contact-independent manner. In addition, adoptive transfer of MDSCs abolished the efficacy of mAb therapy in a mouse model of pancreatic cancer. Inhibition of iNOS restored NK-cell functions and signal transduction. Finally, nonspecific elimination of MDSCs or inhibition of iNOS in vivo significantly improved the efficacy of mAb therapy in a mouse model of breast cancer.Conclusions: MDSCs antagonize NK-cell FcR-mediated function and signal transduction leading to impaired response to mAb therapy in part through nitric oxide production. Thus, elimination of MDSCs or inhibition of nitric oxide production offers a strategy to improve mAb therapy. Clin Cancer Res; 24(8); 1891-904. ©2018 AACR.

Potential therapeutic implications of IL-6/IL-6R/gp130-targeting agents in breast cancer

Interleukin-6 (IL-6) is a pleiotropic cytokine with known multiple functions in immune regulation, inflammation, and oncogenesis. Binding of IL-6 to the IL-6 receptor (IL-6R) induces homodimerization and recruitment of glycoprotein 130 (gp130), which leads to activation of downstream signaling. Emerging evidence suggests that high levels of IL-6 are correlated with poor prognosis in breast cancer patients. IL-6 appears to play a critical role in the growth and metastasis of breast cancer cells, renewal of breast cancer stem cells (BCSCs), and drug resistance of BCSCs, making anti-IL-6/IL-6R/gp130 therapies promising options for the treatment and prevention of breast cancers. However, preclinical and clinical studies of the applications of anti-IL-6/IL-6R/gp130 therapy in breast cancers are limited. In this review, we summarize the structures, preclinical and clinical studies, mechanisms of action of chemical and biological blockers that directly bind to IL-6, IL-6R, or gp130, and the potential clinical applications of these pharmacological agents as breast cancer therapies.

Effects of STING stimulation on macrophages: STING agonists polarize into "classically" or "alternatively" activated macrophages?

Stimulator of interferon genes (STING) was defined as an important molecule for promoting antitumor immunity through mediating type I interferon (IFN) production by sensing its ligands such as cyclic GMP-AMP (cGAMP). Our recent study indeed demonstrated that intratumoral injection of cGAMP showed effective antitumor responses via accumulating activated macrophages in the tumor microenvironment in a STING-dependent manner. Because the antitumor effect of cGAMP was abrogated when macrophages were depleted, the existence of the activated macrophages in the tumor site would be important for effective antitumor immune responses. Macrophages show phenotypic diversity and plasticity and are categorized into several groups by stimulation factors, e.g. IFN-γ and IL-4 for M1 and M2 macrophages, respectively. However, the impact of STING stimulation on the macrophage activation status remains to be evaluated. Here we summarize the complex polarized status of macrophages and the signaling cascade triggered by STING stimulation and also discuss the impact of STING signaling on the macrophage activation status for future directions.

Immune-suppressive effects of interleukin-6 on T-cell-mediated anti-tumor immunity

Accompanied by the growing clinical applications of immunotherapy in the treatment of cancer patients, development of novel therapeutic approaches to reverse the immune-suppressive environment in cancer patients is eagerly anticipated, because the success of cancer immunotherapy is currently limited by immune-suppressive effects in tumor-bearing hosts. Interleukin (IL)-6, a pleotropic proinflammatory cytokine, participates in tumor cell-autonomous processes that are required for their survival and growth, and is therefore known as a poor prognostic factor in cancer patients. In addition, an emerging role of IL-6 in modulating multiple functions of immune cells including T cells, dendritic cells, and macrophages is responsible for the dysfunction of innate and adaptive immunity against tumors. Therefore, the IL-6-targeting approach is of value as a promising strategy for desensitization and prevention of immune-suppressive effects, and should be an effective treatment when combined with current immunotherapies. The aim of the present review is to discuss the immune-suppressive aspects of IL-6, notably with modification of T-cell functions in cancer patients, and their relationship to anti-tumor immune responses and cancer immunotherapy.

Immune-suppressive effects of interleukin-6 on T-cell-mediated anti-tumor immunity

Accompanied by the growing clinical applications of immunotherapy in the treatment of cancer patients, development of novel therapeutic approaches to reverse the immune-suppressive environment in cancer patients is eagerly anticipated, because the success of cancer immunotherapy is currently limited by immune-suppressive effects in tumor-bearing hosts. Interleukin (IL)-6, a pleotropic proinflammatory cytokine, participates in tumor cell-autonomous processes that are required for their survival and growth, and is therefore known as a poor prognostic factor in cancer patients. In addition, an emerging role of IL-6 in modulating multiple functions of immune cells including T cells, dendritic cells, and macrophages is responsible for the dysfunction of innate and adaptive immunity against tumors. Therefore, the IL-6-targeting approach is of value as a promising strategy for desensitization and prevention of immune-suppressive effects, and should be an effective treatment when combined with current immunotherapies. The aim of the present review is to discuss the immune-suppressive aspects of IL-6, notably with modification of T-cell functions in cancer patients, and their relationship to anti-tumor immune responses and cancer immunotherapy.

The spectrum of T cell metabolism in health and disease

In healthy individuals, metabolically quiescent T cells survey lymph nodes and peripheral tissues in search of cognate antigens. During infection, T cells that encounter cognate antigens are activated and - in a context-specific manner - proliferate and/or differentiate to become effector T cells. This process is accompanied by important changes in cellular metabolism (known as metabolic reprogramming). The magnitude and spectrum of metabolic reprogramming as it occurs in T cells in the context of acute infection ensure host survival. By contrast, altered T cell metabolism, and hence function, is also observed in various disease states, in which T cells actively contribute to pathology. In this Review, we introduce the idea that the spectrum of immune cell metabolic states can provide a basis for categorizing human diseases. Specifically, we first summarize the metabolic and interlinked signalling requirements of T cells responding to acute infection. We then discuss how metabolic reprogramming of T cells is linked to disease.

Lack of interleukin-6 in the tumor microenvironment augments type-1 immunity and increases the efficacy of cancer immunotherapy

Conquering immunosuppression in tumor microenvironments is crucial for effective cancer immunotherapy. It is well known that interleukin (IL)‐6, a pleiotropic cytokine, is produced in the tumor‐bearing state. In the present study, we investigated the precise effects of IL‐6 on antitumor immunity and the subsequent tumorigenesis in tumor‐bearing hosts. CT26 cells, a murine colon cancer cell line, were intradermally injected into wild‐type and IL‐6‐deficient mice. As a result, we found that tumor growth was decreased significantly in IL‐6‐deficient mice compared with wild‐type mice and the reduction was abrogated by depletion of CD8⁺ T cells. We further evaluated the immune status of tumor microenvironments and confirmed that mature dendritic cells, helper T cells and cytotoxic T cells were highly accumulated in tumor sites under the IL‐6‐deficient condition. In addition, higher numbers of interferon (IFN)‐γ‐producing T cells were present in the tumor tissues of IL‐6‐deficient mice compared with wild‐type mice. Surface expression levels of programmed death‐ligand 1 (PD‐L1) and MHC class I on CT26 cells were enhanced under the IL‐6‐deficient condition in vivo and by IFN‐γ stimulation in vitro. Finally, we confirmed that in vivo injection of an anti‐PD‐L1 antibody or a Toll‐like receptor 3 ligand, polyinosinic‐polycytidylic acid, effectively inhibited tumorigenesis under the IL‐6‐deficient condition. Based on these findings, we speculate that a lack of IL‐6 produced in tumor‐bearing host augments induction of antitumor effector T cells and inhibits tumorigenesis in vivo, suggesting that IL‐6 signaling may be a promising target for the development of effective cancer immunotherapies.

Interleukin-6/STAT3 signaling as a promising target to improve the efficacy of cancer immunotherapy

Overcoming the immunosuppressive state in tumor microenvironments is a critical issue for improving the efficacy of cancer immunotherapy. Interleukin (IL)‐6, a pleiotropic cytokine, is highly produced in the tumor‐bearing host. Previous studies have indicated that IL‐6 suppresses the antigen presentation ability of dendritic cells (DC) through activation of signal transducer and activator of transcription 3 (STAT3). Thus, we focused on the precise effect of the IL‐6/STAT3 signaling cascade on human DC and the subsequent induction of antitumor T cell immune responses. Tumor‐infiltrating CD11b⁺CD11c⁺ cells isolated from colorectal cancer tissues showed strong induction of the IL‐6 gene, downregulated surface expression of human leukocyte antigen (HLA)‐DR, and an attenuated T cell‐stimulating ability compared with those from peripheral blood mononuclear cells, suggesting that the tumor microenvironment suppresses antitumor effector cells. In vitro experiments revealed that IL‐6‐mediated STAT3 activation reduced surface expression of HLA‐DR on CD14⁺ monocyte‐derived DC. Moreover, we confirmed that cyclooxygenase 2, lysosome protease and arginase activities were involved in the IL‐6‐mediated downregulation of the surface expression levels of HLA class II on human DC. These findings suggest that IL‐6‐mediated STAT3 activation in the tumor microenvironment inhibits functional maturation of DC to activate effector T cells, blocking introduction of antitumor immunity in cancers. Therefore, we propose in this review that blockade of the IL‐6/STAT3 signaling pathway and target molecules in DC may be a promising strategy to improve the efficacy of immunotherapies for cancer patients.

Targeting interlukin-6 to relieve immunosuppression in tumor microenvironment

Immunotolerance is one of the hallmarks of malignant tumors. Tumor cells escape from host immune surveillance through various mechanisms resulting in tumor progression and therapeutic resistance. Interlukin-6 is a proinflammatory cytokine involved in many physiological and pathological processes by integrating with multiple intracellular signaling pathways. Aberrant expression of interlukin-6 is associated with the growth, metastasis, and chemotherapeutic resistance in a wide range of cancers. Interlukin-6 exerts immunosuppressive capacity mostly by stimulating the infiltrations of myeloid-derived suppressor cells, tumor-associated neutrophils, and cancer stem-like cells via Janus-activated kinase/signal transducer and activator of transcription 3 pathway in tumor microenvironment. On this foundation, blockage of interlukin-6 signal may provide potential approaches to novel therapies. In this review, we introduced interlukin-6 pathways and summarized molecular mechanisms related to interlukin-6-induced immunosuppression of tumor cell. We also concluded recent clinical studies targeting interlukin-6 as an immune-based therapeutic intervention in patients with cancer.

Integrating cytokines and angiogenic factors and tumour bulk with selected clinical criteria improves determination of prognosis in advanced renal cell carcinoma

Background:

In two clinical trials of the vascular endothelial growth factor (VEGF) receptor inhibitor pazopanib in advanced renal cell carcinoma (mRCC), we found interleukin-6 as predictive of pazopanib benefit. We evaluated the prognostic significance of candidate cytokines and angiogenic factors (CAFs) identified in that work relative to accepted clinical parameters.

Methods:

Seven preselected plasma CAFs (interleukin-6, interleukin-8, osteopontin, VEGF, hepatocyte growth factor, tissue inhibitor of metalloproteinases (TIMP-1), and E-selectin) were measured using multiplex ELISA in plasma collected pretreatment from 343 mRCC patients participating in the phase 3 registration trial of pazopanib vs placebo (NCT00334282). Tumour burden (per sum of longest diameters (SLD)) and 10 other clinical factors were also analysed for association with overall survival (OS; based on initial treatment assignment).

Results:

Osteopontin, interleukin-6, and TIMP-1 were independently associated with OS in multivariable analysis. A model combining the three CAFs and five clinical variables (including SLD) had higher prognostic accuracy than the International Metastatic Renal Cell Carcinoma Database Consortium criteria (concordance-index 0.75 vs 0.67, respectively), and distinguished two groups of patients within the original intermediate risk category.

Conclusions:

A prognostic model incorporating osteopontin, interleukin-6, TIMP-1, tumour burden, and selected clinical criteria increased prognostic accuracy for OS determination in mRCC patients.

Amino-acid sensing and degrading pathways in immune regulation

Indoleamine 2,3-dioxygenases (IDOs) - belonging in the heme dioxygenase family and degrading tryptophan - are responsible for the de novo synthesis of nicotinamide adenine dinucleotide (NAD⁺). As such, they are expressed by a variety of invertebrate and vertebrate species. In mammals, IDO1 has remarkably evolved to expand its functions, so to become a prominent homeostatic regulator, capable of modulating infection and immunity in multiple ways, including local tryptophan deprivation, production of biologically active tryptophan catabolites, and non-enzymatic cell-signaling activity. Much like IDO1, arginase 1 (Arg1) is an immunoregulatory enzyme that catalyzes the degradation of arginine. Here, we discuss the possible role of amino-acid degradation as related to the evolution of the immune systems and how the functions of those enzymes are linked by an entwined pathway selected by phylogenesis to meet the newly arising needs imposed by an evolving environment.

Immunogenicity is preferentially induced in sparse dendritic cell cultures

We have previously shown that human monocyte-derived dendritic cells (DCs) acquired different characteristics in dense or sparse cell cultures. Sparsity promoted the development of IL-12 producing migratory DCs, whereas dense cultures increased IL-10 production. Here we analysed whether the density-dependent endogenous breaks could modulate DC-based vaccines. Using murine bone marrow-derived DC models we show that sparse cultures were essential to achieve several key functions required for immunogenic DC vaccines, including mobility to draining lymph nodes, recruitment and massive proliferation of antigen-specific CD4+ T cells, in addition to their TH1 polarization. Transcription analyses confirmed higher commitment in sparse cultures towards T cell activation, whereas DCs obtained from dense cultures up-regulated immunosuppressive pathway components and genes suggesting higher differentiation plasticity towards osteoclasts. Interestingly, we detected a striking up-regulation of fatty acid and cholesterol biosynthesis pathways in sparse cultures, suggesting an important link between DC immunogenicity and lipid homeostasis regulation.