IL-17 and IL-21: Their Immunobiology and Therapeutic Potentials.

Studies over the last 2 decades have identified IL-17 and IL-21 as key cytokines in the modulation of a wide range of immune responses. IL-17 serves as a critical defender against bacterial and fungal pathogens, while maintaining symbiotic relationships with commensal microbiota. However, alterations in its levels can lead to chronic inflammation and autoimmunity. IL-21, on the other hand, bridges the adaptive and innate immune responses, and its imbalance is implicated in autoimmune diseases and cancer, highlighting its important role in both health and disease. Delving into the intricacies of these cytokines not only opens new avenues for understanding the immune system, but also promises innovative advances in the development of therapeutic strategies for numerous diseases. In this review, we will discuss an updated view of the immunobiology and therapeutic potential of IL-17 and IL-21.

STAT3 Decoy Oligodeoxynucleotides Suppress Liver Inflammation and Fibrosis in Liver Cancer Cells and a DDC-Induced Liver Injury Mouse Model.

Liver damage caused by various factors results in fibrosis and inflammation, leading to cirrhosis and cancer. Fibrosis results in the accumulation of extracellular matrix components. The role of STAT proteins in mediating liver inflammation and fibrosis has been well documented; however, approved therapies targeting STAT3 inhibition against liver disease are lacking. This study investigated the anti-fibrotic and anti-inflammatory effects of STAT3 decoy oligodeoxynucleotides (ODN) in hepatocytes and liver fibrosis mouse models. STAT3 decoy ODN were delivered into cells using liposomes and hydrodynamic tail vein injection into 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice in which liver injury was induced. STAT3 target gene expression changes were verified using qPCR and Western blotting. Liver tissue fibrosis and bile duct proliferation were assessed in animal experiments using staining techniques, and macrophage and inflammatory cytokine distribution was verified using immunohistochemistry. STAT3 decoy ODN reduced fibrosis and inflammatory factors in liver cancer cell lines and DDC-induced liver injury mouse model. These results suggest that STAT3 decoy ODN may effectively treat liver fibrosis and must be clinically investigated.

Boosting with variant-matched adenovirus-based vaccines promotes neutralizing antibody responses against SARS-CoV-2 Omicron sublineages in mice.

Global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Omicron subvariants, such as BA.4, BA.5 and XBB.1.5, has been leading the recent wave of coronavirus disease 2019 (COVID-19). Unique mutations in the spike proteins of these emerging Omicron subvariants caused immune evasion from the pre-existing protective immunity induced by vaccination or natural infection. Previously, we developed AdCLD-CoV19-1, a non-replicating recombinant adenoviral vector that encodes the receptor binding domain of the spike protein of the ancestral SARS-CoV-2 strain. Based on the same recombinant adenoviral vector platform, updated vaccines that cover unique mutations found in each Omicron subvariant, including BA.1, BA.2, BA.4.1 and BA.5, were constructed. Preclinical studies revealed that each updated vaccine as a booster shot following primary vaccination targeting the ancestral strain improved neutralizing antibody responses against the pseudovirus of its respective strain most effectively. Of note, boosting with a vaccine targeting the BA.1 or BA.2 Omicron subvariant was most effective in neutralization against the pseudovirus of the BA.2.75 strain, whereas BA.4.1/5-adapted booster shots were most effective in neutralization against the BQ.1, BQ1.1 and BF.7 strains. Therefore, it is imperative to develop a vaccination strategy that can cover the unique spike mutations of currently circulating Omicron subvariants in order to prevent the next wave of COVID-19.

The Clinical Significance of Myosteatosis in Survival Outcomes in Patients with Hepatocellular Carcinoma Treated with Sorafenib.

The role of body composition parameters in sorafenib-treated hepatocellular carcinoma (HCC) patients is still not fully elucidated. Here, we aimed to evaluate the impact of computed tomography (CT)-based body composition parameters on the survival of such patients. In this multicenter study, we analyzed the data of 245 sorafenib-treated HCC patients from January 2008 to December 2019. Sarcopenia, visceral obesity, and myosteatosis were defined by using cross-sectional CT images at the third lumbar vertebra level. The effects of these parameters on overall survival (OS) and progression-free survival (PFS) were evaluated. The median age was 67.0 years (interquartile range: 61.0-78.0 year), and 211 patients (86.1%) were male. The median OS and PFS were 7.9 months and 4.8 months, respectively. Vascular invasion (hazard ratio (HR), 1.727; 95% confidence interval (CI), 1.258-2.371; p = 0.001), extrahepatic metastasis (HR, 1.401; 95% CI, 1.028-1.908; p = 0.033), alpha-fetoprotein level > 200 ng/mL (HR, 1.559; 95% CI, 1.105-2.201; p = 0.012), and myosteatosis (HR, 1.814; 95% CI, 1.112-2.960; p = 0.017) were associated with OS. Patient mortality was significantly higher in the group with two or more risk factors than in the group with fewer risk factors. In conclusion, myosteatosis may be a novel prognostic CT-based radiological biomarker in sorafenib-treated HCC patients.

CD8 T-cell subsets: heterogeneity, functions, and therapeutic potential.

CD8 T cells play crucial roles in immune surveillance and defense against infections and cancer. After encountering antigenic stimulation, naïve CD8 T cells differentiate and acquire effector functions, enabling them to eliminate infected or malignant cells. Traditionally, cytotoxic T cells, characterized by their ability to produce effector cytokines and release cytotoxic granules to directly kill target cells, have been recognized as the constituents of the predominant effector T-cell subset. However, emerging evidence suggests distinct subsets of effector CD8 T cells that each exhibit unique effector functions and therapeutic potential. This review highlights recent advancements in our understanding of CD8 T-cell subsets and the contributions of these cells to various disease pathologies. Understanding the diverse roles and functions of effector CD8 T-cell subsets is crucial to discern the complex dynamics of immune responses in different disease settings. Furthermore, the development of immunotherapeutic approaches that specifically target and regulate the function of distinct CD8 T-cell subsets holds great promise for precision medicine.

A Personalized Cancer Vaccine that Induces Synergistic Innate and Adaptive Immune Responses.

To demonstrate potent efficacy, a cancer vaccine needs to activate both innate and adaptive immune cells. Personalized cancer vaccine strategies often require the identification of patient-specific neoantigens; however, the clonal and mutational heterogeneity of cancer cells presents inherent challenges. Here, extracellular nanovesicles derived from alpha-galactosylceramide-conjugated autologous acute myeloid leukemia (AML) cells (ECNV-αGC) are presented as a personalized therapeutic vaccine that activates both innate and adaptive immune responses, bypassing the need to identify patient-specific neoantigens. ECNV-αGC vaccination directly engages with and activates both invariant natural killer T (iNKT) cells and leukemia-specific CD8+ T cells in mice with AML, thereby promoting long-term anti-leukemic immune memory. ECNV-αGC sufficiently serves as an antigen-presenting platform that can directly activate antigen-specific CD8+ T cells even in the absence of dendritic cells, thereby demonstrating a multifaceted cellular mechanism of immune activation. Moreover, ECNV-αGC vaccination results in a significantly lower AML burden and higher percentage of leukemia-free survivors among cytarabine-treated hosts with AML. Human AML-derived ECNV-αGCs activate iNKT cells in both healthy individuals and patients with AML regardless of responsiveness to conventional therapies. Together, autologous AML-derived ECNV-αGCs may be a promising personalized therapeutic vaccine that efficiently establishes AML-specific long-term immunity without requiring the identification of neoantigens.

Triterpenoid saponins from Camellia sinensis roots with cytotoxic and immunomodulatory effects.

Camellia sinensis L. (Theaceae) leaves have been used as a beverage in both Eastern and Western cultures for a long time, while its root has not been intensively studied. In this study, seven undescribed triterpenoid saponins (1-7) and twelve known saponins (8-19) with different combinations of substituents, such as oxygenated isoprenyl substituents and sugar moieties, and lengths of sugar chains, were isolated from the C. sinensis roots. Their structures were unequivocally determined using one- and two-dimensional nuclear magnetic resonance data and acid hydrolysis analysis. Investigation of the biological activities of isolated compounds revealed that only those without functional acetyl groups exhibited cytotoxic activities against mouse and human cancer cells (B16F10) and human cervical cancer cell line (HeLa) at 50 µM. Compounds with an aldehyde group at C-23 of aglycone showed immunomodulatory activity against Th1 and Th17 cells at 10 µM. Ten compounds with biological activities from C. sinensis roots extracts, including three previously undescribed ones (3, 6, and 7), were identified.

Nanovesicle-Mediated Targeted Delivery of Immune Checkpoint Blockades to Potentiate Therapeutic Efficacy and Prevent Side Effects.

Despite the clinically proven efficacies of immune checkpoint blockades, including anti-cytotoxic T lymphocyte-associated protein 4 antibody (αCTLA-4), the low response rate and immune-related adverse events (irAEs) in cancer patients represent major drawbacks of the therapy. These drawbacks of αCTLA-4 therapy are mainly due to the suboptimal activation of tumor-specific cytotoxic T lymphocytes (CTLs) and the systemic nonspecific activation of T cells. To overcome such drawbacks, αCTLA-4 is delivered by dendritic cell-derived nanovesicles presenting tumor antigens (DCNV-TAs) that exclusively interact with tumor-specific T cells, leading to selective activation of tumor-specific CTLs. Compared to conventional αCTLA-4 therapy, treatment with αCTLA-4-conjugated DCNV-TAs significantly inhibits tumor growth and reduces irAEs in syngeneic tumor-bearing mice. This study demonstrates that the spatiotemporal presentation of both αCTLA-4 and tumor antigens enables selective activation of tumor-specific T cells and potentiates the antitumor efficacy of αCTLA-4 without inducing systemic irAEs.

Inhibition of topoisomerase I shapes antitumor immunity through the induction of monocyte-derived dendritic cells.

Understanding the rationale of combining immunotherapy and other anticancer treatment modalities is of great interest because of interpatient variability in single-agent immunotherapy. Here, we demonstrated that topoisomerase I inhibitors, a class of chemotherapeutic drugs, can alter the tumor immune landscape, corroborating their antitumor effects combined with immunotherapy. We observed that topotecan-conditioned TC-1 tumors were occupied by a vast number of monocytic cells that highly express CD11c, CD64, and costimulatory molecules responsible for the favorable changes in the tumor microenvironment. Ly6C+MHC-II+CD11chiCD64hi cells, referred to as topotecan-induced monocyte-derived dendritic cells (moDCs), proliferate and activate antigen-specific CD8+ T cells to levels equivalent to those of conventional DCs. Phenotypic changes in Ly6C+ cells towards moDCs were similarly induced by exposure to topotecan in vitro, which was more profoundly facilitated in the presence of tumor cells. Notably, anti-M-CSFR reversed the acquisition of DC-like properties of topotecan-induced moDCs, leading to the abolition of the antitumor effect of topotecan combined with a cancer vaccine. In short, topoisomerase I inhibitors generate monocyte-derived antigen-presenting cells in tumors, which could be mediated by M-CSF-M-CSFR signaling.

Type 17 immunity promotes the exhaustion of CD8+ T cells in cancer.

BACKGROUND: Multiple types of immune cells producing IL-17 are found in the tumor microenvironment. However, their roles in tumor progression and exhaustion of CD8+ tumor-infiltrating lymphocytes (TILs) remain unclear. METHODS: To determine the role of type 17 immunity in tumor, we investigated the growth of B16F10 melanoma and the exhaustion of CD8+ TILs in Il17a-/- mice, Il17aCreR26DTA mice, RORγt inhibitor-treated mice, or their respective control mice. Adoptive transfer of tumor-specific IL-17-producing T cells was performed in B16F10-bearing congenic mice. Anti-CD4 or anti-Ly6G antibodies were used to deplete CD4+ T cells or CD11b+Gr-1hi myeloid cells in vivo, respectively. Correlation between type 17 immunity and T cell exhaustion in human cancer was evaluated by interrogating TCGA dataset. RESULTS: Depletion of CD4+ T cells promotes the exhaustion of CD8+ T cells with a concomitant increase in IL-17-producing CD8+ T (Tc17) cells in the tumor. Unlike IFN-γ-producing CD8+ T (Tc1) cells, tumor-infiltrating Tc17 cells exhibit CD103+KLRG1-IL-7Rαhi tissue resident memory-like phenotypes and are poorly cytolytic. Adoptive transfer of IL-17-producing tumor-specific T cells increases, while depletion of IL-17-producing cells decreases, the frequency of PD-1hiTim3+TOX+ terminally exhausted CD8+ T cells in the tumor. Blockade of IL-17 or RORγt pathway inhibits exhaustion of CD8+ T cells and also delays tumor growth in vivo. Consistent with these results, human TCGA analyses reveal a strong positive correlation between type 17 and CD8+ T cell exhaustion signature gene sets in multiple cancers. CONCLUSION: IL-17-producing cells promote terminal exhaustion of CD8+ T cells and tumor progression in vivo, which can be reversed by blockade of IL-17 or RORγt pathway. These findings unveil a novel role for IL-17-producing cells as tumor-promoting cells facilitating CD8+ T cell exhaustion, and propose type 17 immunity as a promising target for cancer immunotherapy.

A comparison of the effectiveness of QuEChERS, FaPEx and a modified QuEChERS method on the determination of organochlorine pesticides in ginseng.

This study provides a review of methods used in the determination of organochlorine pesticides (OCPs) in ginseng and compares the effectiveness of three extraction methods (Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), a modified QuEChERS and a Fast Pesticide Extraction (FaPEx)) in the analyses of 20 OCPs in ginseng root samples. For each method, sample mass, solvent volume and sorbent mass were varied to identify the optimum combination to effectively isolate analytes of interest from the complex sample matrix. Extracts were analyzed using the gas chromatography-µ-electron capture detector (GC-µ-ECD), and confirmatory analyses performed by gas chromatography-tandem-mass spectrometry (GC-MS/MS). Eighteen out of 20 OCPs spiked onto in-house prepared ginseng samples produced acceptable recoveries (51-156%) when extracted using QuEChERS and FaPEx. All 20 analytes, including dichlorodiphenyldichloroethane (p, p'- DDD) and dichlorodiphenyltrichloroethane (o, p'-DDT), produced acceptable recoveries (51-129%) with the use of a modified QuEChERS method. The applicability of the modified QuEChERS method was demonstrated through the analysis of ginseng samples grown in endosulfan-treated soil. The samples were analyzed by both GC-µ-ECD and GC-MS/MS with no significant difference identified in the results of each analytical method. This study highlights the applicability of the modified QuEChERS method, in combination with GC- µ-ECD, to determine organochlorine pesticides in ginseng. This may be especially useful for laboratories in developing countries and less advanced institutions without access to MS/MS instrumentation.

Addition of liver stiffness enhances the predictive accuracy of the PAGE-B model for hepatitis B-related hepatocellular carcinoma.

BACKGROUND: The modified PAGE-B (mPAGE-B) and PAGE-B models reliably predict the risk of developing chronic hepatitis B (CHB)-related hepatocellular carcinoma (HCC). AIM(S): To investigate whether the addition of liver stiffness (LS) value, assessed using transient elastography, enhanced the predictive accuracies of these models METHODS: Patients with CHB who started anti-viral therapy (AVT) between 2007 and 2017 were enrolled. The training (Yonsei University Hospital) and validation (seven Korean referral institutes) cohorts contained 1211 and 973 patients, respectively. RESULTS: Based on multivariate analysis, older age (hazard ratio [HR] = 1.051, 95% confidence interval [CI] = 1.031-1.071), male sex (HR = 2.265, 95% CI = 1.463-3.506), lower platelet count (HR = 0.993, 95% CI = 0.989-0.997) and greater LS values (HR = 1.015, 95% CI = 1.002-1.028) were independently associated with an increased risk of HCC development (all P < 0.05). Thus, we developed a modified PAGELS -B model (maximum score 34) that included age, male sex, platelet count and LS value. The integrated area under the curve of the modified PAGELS model was greater than those of the PAGE-B and mPAGE-B models (0.760 vs 0.714 and 0.716, respectively) in the derivation dataset. The cumulative HCC incidence was significantly higher in the high-risk (modified PAGE-BLS score ≥ 24) group than in the intermediate-risk (modified PAGELS -B score 12-24) or low-risk (modified PAGELS -B score < 12) group (all P < 0.001). Similar results were observed in the validation cohort. CONCLUSIONS: The predictive accuracies of the PAGE-B and mPAGE-B models were validated in Korean patients with CHB receiving AVT. However, the modified PAGELS -B model featuring the addition of LS value showed higher predictability than the PAGE-B and mPAGE-B models.

Dynamics of liver stiffness-based risk prediction model during antiviral therapy in patients with chronic hepatitis B.

OBJECTIVE: The liver stiffness-based risk prediction models predict hepatocellular carcinoma (HCC) development. We investigated the influence of antiviral therapy (AVT) on liver stiffness-based risk prediction model in patients with chronic hepatitis B (CHB). METHODS: Patients with CHB who initiated AVT were retrospectively recruited from 13 referral Korean institutes. The modified risk estimation for hepatocellular carcinoma in chronic hepatitis B (mREACH-B) model was selected for the analysis. RESULTS: Between 2007 and 2015, 1034 patients with CHB were recruited. The mean age of the study population (639 men and 395 women) was 46.8 years. During AVT, the mREACH-B score significantly decreased from the baseline to 3 years of AVT (mean 9.21 → 7.46, P < 0.05) and was maintained until 5 years of AVT (mean 7.23, P > 0.05). The proportion of high-risk patients (mREACH-B score ≥11) was significantly reduced from the baseline to 2 years of AVT (36.4% → 16.4%, P < 0.001) and was maintained until 5 years of AVT (12.2%, P > 0.05). The mREACH-B scores at baseline and 1 year of AVT independently predicted HCC development (hazard ratio = 1.209-1.224) (all P < 0.05). The cumulative incidence rate of HCC was significantly different at 5 years of AVT among risk groups (high vs. high-intermediate vs. low-intermediate vs. low) from baseline (4.5% vs. 3.2% vs. 1.5% vs. 0.8%) and 1 year (11.8% vs. 4.6% vs. 1.8% vs. 0.6%) (all P < 0.05, log-rank tests). CONCLUSIONS: The mREACH-B score was dynamically changed during AVT. Thus, repeated assessment of the mREACH-B score is required to predict the changing risk of HCC development in patients with CHB undergoing AVT.

Changes in Characteristics of Patients with Liver Cirrhosis Visiting a Tertiary Hospital over 15 Years: a Retrospective Multi-Center Study in Korea.

BACKGROUND: Liver cirrhosis has become a heavy burden not only for patients, but also for our society. However, little is known about the recent changes in clinical outcomes and characteristics of patients with cirrhosis-related complications in Korea. Therefore, we aimed to evaluate changes in characteristics of patients with liver cirrhosis in Daegu-Gyeongbuk province in Korea over the past 15 years. METHODS: We retrospectively reviewed the medical records of 15,716 liver cirrhotic patients from 5 university hospitals in Daegu-Gyeongbuk province from 2000 to 2014. The Korean Standard Classification of Diseases-6 code associated with cirrhosis was investigated through medical records and classified according to the year of first visit. RESULTS: A total of 15,716 patients was diagnosed with cirrhosis. A number of patients newly diagnosed with cirrhosis has decreased each year. In 2000, patients were most likely to be diagnosed with hepatitis B virus (HBV) cirrhosis, followed by alcoholic cirrhosis. There was a significant decrease in HBV (P < 0.001), but alcohol, hepatitis C virus (HCV), and non-alcoholic fatty liver disease (NAFLD) showed a significant increase during the study period (alcohol, P = 0.036; HCV, P = 0.001; NAFLD, P = 0.001). At the time of initial diagnosis, the ratio of Child-Turcotte-Pugh (CTP) class A gradually increased from 23.1% to 32.9% (P < 0.001). The most common cause of liver-related hospitalization in 2000 was hepatocellular carcinoma (HCC) (25.5%); in 2014, gastrointestinal bleeding with esophageal and gastric varices (21.4%) was the most common cause. Cases of hospitalization with liver-related complication represented 76.4% of all cases in 2000 but 70.9% in 2014. Incidence rate of HCC has recently increased. In addition, HCC-free survival was significantly lower in CTP class A than in classes B and C. Finally, there was significant difference in HCC occurrence according to causes (P < 0.001). HBV and HCV cirrhosis had lower HCC-free survival than alcoholic and NAFLD cirrhosis. CONCLUSION: In recent years, the overall number of cirrhosis patients has decreased. This study confirmed the recent trend in decrease of cirrhosis, especially of cirrhosis due to HBV, and the increase of HCV, alcoholic and NAFLD cirrhosis. Targeted screening for at-risk patients will facilitate early detection of liver diseases allowing effective intervention and may have decreased the development of cirrhosis and its complications.

Child-Pugh, MELD, MELD-Na, and ALBI scores: which liver function models best predicts prognosis for HCC patient with ascites?

OBJECTIVE: It remains controversial whether certain treatments should apply to HCC patients with ascites due to concerns about worsening liver function. The objective of the present study is to compare the prognostic performance of 4 liver function models currently in use for HCC patients with ascites. METHODS: A total of 437 treatment-naïve, newly diagnosed HCC patients were analyzed. The predictive performance of Child-Pugh, MELD, MELD-Na, and ALBI scores were examined using ROC curve analysis. RESULTS: MELD-Na score showed good performance in predicting 1-, 2-, and 3-year mortality, particularly 1-year mortality. MELD-Na score significantly increased at 30 days after treatment in cases initially receiving best supportive care (14-17, p < .001), TACE (9-11, p < .001), and other treatment (radiotherapy, sorafenib, or systemic chemotherapy) (9-11, p = .021). For patients with advanced tumor stage and MELD-Na score ≥12, HCC-specific treatment did not offer significantly better prognosis compared with only the best supportive care (median survival: 2.2 vs. 1.8 months for HCC-specific treatment vs. best supportive care, p = .15). CONCLUSION: MELD-Na can effectively identify liver functional reserve and prognosis in HCC patients with ascites. MELD-Na, together with the tumor stage, may help establish a therapeutic strategy for them.

Enhanced Immunogenicity of Engineered HER2 Antigens Potentiates Antitumor Immune Responses.

For cancer vaccines, the selection of optimal tumor-associated antigens (TAAs) that can maximize the immunogenicity of the vaccine without causing unwanted adverse effects is challenging. In this study, we developed two engineered Human epidermal growth factor receptor 2 (HER2) antigens, K965 and K1117, and compared their immunogenicity to a previously reported truncated HER2 antigen, K684, within a B cell and monocyte-based vaccine (BVAC). We found that BVAC-K965 and BVAC-K1117 induced comparable antigen-specific antibody responses and antigen-specific T cell responses to BVAC-K684. Interestingly, BVAC-K1117 induced more potent antitumor activity than the other vaccines in murine CT26-HER2 tumor models. In addition, BVAC-K1117 showed enhanced antitumor effects against truncated p95HER2-expressing CT26 tumors compared to BVAC-K965 and BVAC-K684 based on the survival analysis by inducing T cell responses against intracellular domain (ICD) epitopes. The increased ICD epitope-specific T cell responses induced by BVAC-K1117 compared to BVAC-K965 and BVAC-K684 were recapitulated in human leukocyte antigen (HLA)-untyped human PBMCs and HLA-A*0201 PBMCs. Furthermore, we also observed synergistic antitumor effects between BVAC-K1117 and anti-PD-L1 antibody treatment against CT26-HER2 tumors. Collectively, our findings demonstrate that inclusion of a sufficient number of ICD epitopes of HER2 in cellular vaccines can improve the antitumor activity of the vaccine and provide a way to optimize the efficacy of anticancer cellular vaccines targeting HER2.

IL-17-Producing Cells in Tumor Immunity: Friends or Foes?

IL-17 is produced by RAR-related orphan receptor gamma t (RORγt)-expressing cells including Th17 cells, subsets of γδT cells and innate lymphoid cells (ILCs). The biological significance of IL-17-producing cells is well-studied in contexts of inflammation, autoimmunity and host defense against infection. While most of available studies in tumor immunity mainly focused on the role of T-bet-expressing cells, including cytotoxic CD8+ T cells and NK cells, and their exhaustion status, the role of IL-17-producing cells remains poorly understood. While IL-17-producing T-cells were shown to be anti-tumorigenic in adoptive T-cell therapy settings, mice deficient in type 17 genes suggest a protumorigenic potential of IL-17-producing cells. This review discusses the features of IL-17-producing cells, of both lymphocytic and myeloid origins, as well as their suggested pro- and/or anti-tumorigenic functions in an organ-dependent context. Potential therapeutic approaches targeting these cells in the tumor microenvironment will also be discussed.

GITR Agonism Triggers Antitumor Immune Responses through IL21-Expressing Follicular Helper T Cells.

Although treatment with the glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) agonistic antibody (DTA-1) has shown antitumor activity in various tumor models, the underlying mechanism is not fully understood. Here, we demonstrate that interleukin (IL)-21-producing follicular helper T (Tfh) cells play a crucial role in DTA-1-induced tumor inhibition. The administration of DTA-1 increased IL21 expression by Tfh cells in an antigen-specific manner, and this activation led to enhanced antitumor cytotoxic T lymphocyte (CTL) activity. Mice treated with an antibody that neutralizes the IL21 receptor exhibited decreased antitumor activity when treated with DTA-1. Tumor growth inhibition by DTA-1 was abrogated in Bcl6 fl/fl Cd4 Cre mice, which are genetically deficient in Tfh cells. IL4 was required for optimal induction of IL21-expressing Tfh cells by GITR costimulation, and c-Maf mediated this pathway. Thus, our findings identify GITR costimulation as an inducer of IL21-expressing Tfh cells and provide a mechanism for the antitumor activity of GITR agonism.

Targeting ST2 expressing activated regulatory T cells in Kras-mutant lung cancer.

Oncogenic KRAS-mutant lung cancers remain treatment refractory. A better understanding of the immune response of KRAS-mutant lung cancers is required to facilitate the development of potential therapeutic strategies. Regulatory T cells (Tregs) are a subset of immune cells that promote tumor progression through suppressing anti-tumor immune response. Here, we used KrasG12D lung cancer mice to examine the characteristics of tumor-infiltrating Tregs. In tumor-bearing animals, Tregs are increased during tumor progression. Of note, a majority of Tregs that localized in lung tumors of Kras-mutant mice expressed ST2, a receptor for IL-33, which are different from Tregs in secondary lymphoid organs. To investigate the function of local Tregs influencing immune response in primary lung tumor development, we used anti-ST2 antibody to deplete Tregs in lung tumors of Kras-mutant mice. Treatment of Kras-mutant mice with anti-ST2 antibody resulted in depletion of activated Tregs in lung tumor while leaving Tregs in secondary lymphoid organs intact. Also, localized Tregs depletion led to a significant reduction in lung tumor burden. Immune response after Tregs depletion in tumors showed restoration of NK cell activity and enhanced Th1 activity, with increased CD8 cytotoxic T cell response. In addition, we found that the M2 macrophage signature in lung tumors was suppressed upon Tregs depletion, accompanied by upregulation of surface expression of MHC-II molecules and reduced expression of Arg1, Mmp12, Cxcl2, and Chi3l3. These data suggest that therapeutic strategies targeting activated Tregs in lung cancer have the potential to restrain tumor progression by enhancing anti-tumor immunity.