Converting“cold”to“hot”:epigenetics strategies to improve immune therapy effect by regulating tumor-associated immune suppressive cells

Significant developments in cancer treatment have been made since the advent of immune therapies.However,there are still some patientswithmalignant tumors who do not benefit from immunotherapy.Tumors without immunogenicity are called“cold”tumors which are unresponsive to immunotherapy,and the opposite are“hot”tumors.Immune suppressive cells(ISCs)refer to cells which can inhibit the immune response such as tumor-associated macrophages(TAMs),myeloid-derived suppressor cells(MDSCs),regulatory T(Treg)cells and so on.The more ISCs infiltrated,the weaker the immunogenicity of the tumor,showing the characteristics of“cold”tumor.The dysfunction of ISCs in the tumor microenvironment(TME)may play essential roles in insensitive therapeutic reaction.Previous studies have found that epigeneticmechanisms play an important role in the regulation of ISCs.Regulating ISCs may be a new approach to transforming“cold”tumors into“hot”tumors.Here,we focused on the function of ISCs in the TME and discussed how epigenetics is involved in regulating ISCs.In addition,we summarized the mechanisms by which the epigenetic drugs convert immunotherapy-insensitive tumors into immunotherapy-sensitive tumors which would be an innovative tendency for future immunotherapy in“cold”tumor.

Chronic social defeat stress‑induced depression reduces BCG efficacy by promoting regulatory T‑cell levels in mice

Despite the initial successes of the Bacillus Calmette-Guerin(BCG)vaccine in children,its efficacy against tuberculosis is highly variable.There is a lack of understanding about how mental conditions influence BCG vaccination.Here,we used the chronic social defeat stress(CSDS)model to explore the effects of depression on BCG vaccination efficacy.We observed higher lung and spleen bacterial loads and a lower organ index in depressed compared to BCG mice.Meanwhile,a relatively lower T cell protective efficacy was observed in both compared to control and BCG mice via a mycobacterium growth inhibition assay(MGIA).Cytokine expression of IL-12p40,IL-1β,IL-17,TNF-αand IFN-γwas reduced,whereas the expression of IL-10 and IL-5 was increased in the spleen of both compared to BCG mice.Moreover,the proportions of CD4^(+)IFN-γ^(+),CD8^(+)IFN-γ^(+)T lymphocytes and CD4^(+)effector/central memory T cells were reduced in the splenocytes of the depressed BCG mice.Depression promotes CD4^(+)regulatory T cells(Treg)and myeloid-derived suppressor cell(MDSC)generation in depressed mice,contributing to the reduced pro-inflammatory immune response upon BCG vaccination.This study provides insight into the decreased protective immunity by BCG vaccination attributable to depression in mice.

Human immune suppression is inducible by trichosanthin via CD8 cell-mediated pathway

Thichosanthin(Tk), a polypeptide with 249 amino acid residues isolated and purified from a Chinese medicinal herb, showed the capability of inducing abortion and was able to inhibit tumor growth and HIV replication. Owing to sequence homology of the peptide with a ribosomeinactivating protein, the downward activity of Tk was suggested to be related to its cytotoxic property. We report here, however, that Tk could exert potent inhibitory effects on human lymphoproliferative responses in vitro to allogeneic, mitogenic and soluble antigens with 50% inhibition doses ranged between 0.05 and 0.5 μg/ml. The lowresponsiveness caused by Tk was not due to toxic cytolysis. Rather, evidences suggested that, in the dose range adopted, the Tk-induced inhibition was attributable, at least in part, to immune suppression, in view of (1) Tk was more effective in the early stage of alloreactivity; (2)Suppression also occurred if responder cells were pulsetreated with Tk rather than cocultured; (3) Irradiated Tk-pulsed cells were capable of inducing suppression in a Tk-free culture; (4) Suppression could also be transferred by the supernatants of Tk-pulsed cultured cells; (5) Tkinduced immune suppression was diminished by depletion of CD8+ cells from the culture, and, finally; (6) Adding CD8+ cells back to the culture could restore the suppres Trichosanthin-induced humall immune suppression sion. Thus the possibility that Tk might function as a down-regulator by immunological mechanisms in human immune responses is discussed.

Effect of Fuzheng Jiedu granule on immunological function and level of immune-related cytokines in immune-suppressed mice

Fuzheng Jiedu granule exhibits a number of health benefits and it is thought that the mechanisms involved in these effects are due to the modulation of immunity. In this article, we studied the effect of Fuzheng Jiedu granule on immunological function and the expression of immune-related cytokines in immune-suppressed mice. 72 mice were randomly divided into six groups, with 12 in each group. The control groups included an untreated group, a negative control group（Cyclophosphamide） and a positive control group（Astragalus polysaccharide）. There were three treated groups, which were given different doses of Fuzheng Jiedu granule： a low dose（100 mg kg^（–1））, a medium dose（400 mg kg^（–1）） and a high dose（600 mg kg^（–1））. With the exception of the untreated control animals, each group received an intraperitoneal injection of Cyclophosphamide（100 mg kg^（–1）） for 3 days to establish the immune-suppressed model. Mice were then treated for 19 consecutive days and, 24 h after the last treatment, blood was taken for the eyeballs and serum separation was performed. Analysis was made of the levels of related cytokines（IgA, IgG, IgM, IL-6, IFN-γ, C3, C4 and TNF-α）, the transformation of lymphocytes and the immune organ indexes. The results showed that Fuzheng Jiedu granule can improve the levels of cytokines, the rate of proliferation of lymphocytes and the immune organ indexes of immune-suppressed mice.

Up-regulation of Tim-3 Expression Contributes to Development of Burn-induced T Cell Immune Suppression in Mice

T cell immunoglobulin and mucin domain 3 （Tim-3） is well known to negatively regulate T cells responses, but its role in burn-induced T cells immune suppression remains unclear. In the present study, in order to identify the relationship between Tim-3 expression and post-burn T cells immune suppression, C57BL/6 mice were subjected to burn injury or sham injury, and the liver and spleen were harvested at the day 1 after operation. The expression level of Tim-3 on hepatic or splenic T cells and the functional properties of Tim-3＋ T cells were evaluated. It was found burn injury induced dramatically elevated Tim-3 expression on both hepatic and splenic CD4＋ and CD8＋ T cells in contrast with the post-burn depletion of T cells. Furthermore, Tim-3 expression was correlated with the suppressive phenotype of T cells following burn injury, including increased expression of anti-inflammatory cytokine IL-10, decreased expression of pro-inflammatory cytokines IFN-γ and TNF-α, reduced T cell proliferation and elevated co-expression of Tim-3 and PD-1. Moreover, Tim-3＋ T cells subsets were more prone to spontaneous apoptosis than Tim-3- T cells subsets. Our findings reinforce the idea that the up-regulated expression of Tim-3 on T cells after burn injury plays an important role in the development and maintenance of burn-induced T cell immune suppression.

Immune phenotypes of prostate cancer cells: Evidence of epithelial immune cell-like transition?

Prostate cancers(PCa)have been reported to actively suppress antitumor immune responses by creating an immune-suppressive microenvironment.There is mounting evidence that PCas may undergo an‘‘Epithelial Immune Cell-like Transition’’(EIT)by expressing molecules conventionally associated with immune cells(e.g.,a variety of cytokines/receptors,immune transcription factors,Ig motifs,and immune checkpoint molecules),which subsequently results in the suppression of anti-cancer immune activity within the tumor microenvironment.Recent progress within the field of immune therapy has underscored the importance of immune checkpoint molecules in cancer development,thus leading to the development of novel immunotherapeutic approaches.Here,we review the expression of select immune checkpoint molecules in PCa epithelial and associated immune cells,with particular emphasis on clinical data supporting the concept of an EIT-mediated phenotype in PCa.Furthermore,we summarize current advances in anti-immune checkpoint therapies,and provide perspectives on their potential applicability.

<i>Leishmania donovani</i>-Induced Immune Dysregulation among Sudanese Patients with Visceral and Post Kala-Azar Dermal Leishmaniases: Possible Roles in Pathogenesis

L. donovani infections (visceral and post kala-azar dermal leishmaniases) are characterized by infection-induced reversible immune suppression. Autoimmunity is a well-documented phenomenon among patients with primary immune deficiencies. This study aimed to study auto-immune phenomena accompanying L. donovani infections. In a prospective case-controlled study and following informed consent, 155 individuals with visceral leishmaniasis (VL;n = 62), post kala-azar dermal leishmaniasis (PKDL;n = 31) and apparently healthy volunteers (n = 62) were recruited. Sera antinuclear (ANA), anti-dsDNA, anti-thyroid peroxidase (TPO), anti-smooth muscles (ASMA) and F-actin auto-antibodies were measured using ELISA and indirect immune-fluorescence assay. The mean ages of VL, PDKL patients and apparently healthy volunteers were: 17.5 ± 12.5, 15.0 ± 7.0 and 17.5 ± 9.5 years with Male:Female ratios of 2:0, 1:2 and 1:5 respectively. Significantly high frequencies of F-actin (74.2%;46/62) and ASMA (50%;31/62) auto-antibodies were seen among VL patients (p = 0.003, p = 0.001) compared to apparently healthy volunteers. Likewise, significantly high frequencies of F-actin (64.5%;20/31;p = 0.001), ASMA (42%;13/31;p = 0.003), ANA (36%;11/31;p = 0.001) and anti-dsDNA (16%;5/31;p = 0.01) auto-antibodies were seen among PKDL patients. Development of tissue-based autoantibodies in L. donovani infections probably indicates loss of peripheral tolerance with activation of circulating auto-reactive T and B cells probably contributing to disease pathogenesis (increased bilirubin/liver enzymes, prolonged QT interval/arrythmias and blood cytopenias). In conclusion, L. donovani infection-induced immune suppression with development of tissue-based auto-antibodies is prevalent among Sudanese patients with VL and PKDL leishmaniases and contributes to some aspects of the disease pathogenesis.

Emerging roles of plasmacytoid dendritic cell crosstalk in tumor immunity

Plasmacytoid dendritic cells(pDCs)are a pioneer cell type that produces type I interferon(IFN-I)and promotes antiviral immune responses.However,they are tolerogenic and,when recruited to the tumor microenvironment(TME),play complex roles that have long been a research focus.The interactions between p DCs and other components of the TME,whether direct or indirect,can either promote or hinder tumor development;consequently,p DCs are an intriguing target for therapeutic intervention.This review provides a comprehensive overview of p DC crosstalk in the TME,including crosstalk with various cell types,biochemical factors,and microorganisms.An in-depth understanding of p DC crosstalk in TME should facilitate the development of novel p DC-based therapeutic methods.

Exosome regulation of immune response mechanism:Pros and cons in immunotherapy

Due to its multiple features,including the ability to orchestrate remote communication between different tissues,the exosomes are the extracellular vesicles arousing the highest interest in the scientific community.Their size,established as an average of 30-150 nm,allows them to be easily uptaken by most cells.According to the type of cells-derived exosomes,they may carry specific biomolecular cargoes used to reprogram the cells they are interacting with.In certain circumstances,exosomes stimulate the immune response by facilitating or amplifying the release of foreign antigens-killing cells,inflammatory factors,or antibodies(immune activation).Meanwhile,in other cases,they are efficiently used by malignant elements such as cancer cells to mislead the immune recognition mechanism,carrying and transferring their cancerous cargoes to distant healthy cells,thus contributing to antigenic invasion(immune suppression).Exosome dichotomic patterns upon immune system regulation present broad advantages in immunotherapy.Its perfect comprehension,from its early biogenesis to its specific interaction with recipient cells,will promote a significant enhancement of immunotherapy employing molecular biology,nanomedicine,and nanotechnology.

Research progress of traditional Chinese medicine in regulating tumor microenvironment

The tumor microenvironment(TME)plays a crucial role in facilitating tumorigenesis and progression.Consequently,there is significant research interest within the oncology community in developing interventions that target the TME.Extensive research has been conducted on the mechanism of traditional Chinese medicine(TCM)in tumor therapy,revealing notable similarities between its theoretical framework and that of the TME.TCM has the ability to regulate various components of the microenvironment,including the modulation of proportions of T cell subsets,enhancement of the quantity and activity of NK cells,regulation of polarization of tumor-associated macrophages,suppression of expression of myeloid-derived suppressor cells,reduction of accumulation of tumor-associated endothelial cells,downregulation of the quantity and function of tumor-associated fibroblasts,and modulation of the architecture of the extracellular matrix.These multifaceted interventions ultimately lead to the attainment of anti-tumor objectives.This comprehensive review encompasses a thorough analysis of relevant literature from both domestic and international sources,with a specific emphasis on elucidating the mechanisms through which TCM compound formulas,single drugs,and monomeric components regulate the TME.

Gastric cancer cells induce human CD4^+ Foxp3^+ regulatory T cells through the production of TGF-β1

AIM: To elucidate the molecular and cellular features responsible for the increase of regulatory T cells (Tregs) in gastric cancer. METHODS: The frequencies of CD4 + Foxp3 + Tregs and the level of transforming growth factor-β1 (TGF-β1) were analyzed from 56 patients with gastric cancer byflow cytometry and enzyme-linked immunosorbent assay respectively. Foxp3 gene expression was analyzed by real-time polymerase chain reaction. The gastric cancer microenvironment was modeled by establishing the coculture of gastric cancer cell line, MGC-803, with sorting CD4 + T cells. The normal gastric mucosa cell line, GES-1, was used as the control. The production of TGF-β1 was detected in supernatant of MGC and GES-1. The carboxyfluorescein diacetatesuccinimidyl ester (CFSE) dilution assay was performed to evaluate the proliferation characteristics of induced Tregs. Neutralizing anti-TGF-β1 antibody was added to the co-culture system for neutralization experiments. RESULTS: The level of serum TGF-β1 in gastric cancer patients (15.1 ± 5.5 ng/mL) was significantly higher than that of the genderand age-matched healthy controls (10.3 ± 3.4 ng/mL) (P < 0.05). Furthermore, the higher TGF-β1 level correlated with the increased population of CD4 + Foxp3 + Tregs in advanced gastric cancer (r = 0.576, P < 0.05). A significant higher frequency of CD4 + Foxp3 + Tregs was observed in PBMCs cultured with the supernatant of MGC than GES-1 (10.6% ± 0.6% vs 8.7% ± 0.7%, P < 0.05). Moreover, using the purified CD4 + CD25 T cells, we confirmed that the increased Tregs were mainly induced from the conversation of CD4 + CD25 naive T cells, and induced Tregs were functional and able to suppress the proliferation of effector T cells. Finally, we demonstrated that gastric cancer cells induced the increased CD4 + Foxp3 + Tregs via producing TGF-β1. Gastric cancer cells upregulated the production of TGF-β1 and blockade of TGF-β1 partly abrogated Tregs phenotype. CONCLUSION: Gastric cancer cell can induce Tregs development via producing TGF-β1, by which the existence of cross-talk between the tumor and immune cells might regulate anti-tumor immune responses.

Downregulation of orosomucoid 2 acts as a prognostic factor associated with cancer-promoting pathways in liver cancer

BACKGROUND Liver cancer has a high mortality and morbidity rate throughout the world.In clinical practice,the prognosis of liver cancer patients is poor,and the complex reasons contribute to treatment failures,including fibrosis,hepatitis viral infection,drug resistance and metastasis.Thus,screening novel prognostic biomarkers is of great importance for guiding liver cancer therapy.Orosomucoid genes(ORMs)encode acute phase plasma proteins,including orosomucoid 1(ORM1)and ORM2.Previous studies showed their upregulation upon inflammation,but the specific function of ORMs has not yet been determined,especially in the development of liver cancer.AIM To determine the expression of ORMs and their potential function in liver cancer.METHODS Analysis of the expression of ORMs in different human tissues was performed on data from the HPA RNA-seq normal tissues project.The expression ratio of ORMs was determined using the HCCDB database,including the ratio between liver cancer and other cancers,normal liver and other normal tissues,liver cancer and adjacent normal liver tissues.Analysis of ORM expression in different cancer types was performed using The Cancer Genome Atlas and TIMER database.The expression of ORMs in liver tumor tissues and adjacent normal tissues were further confirmed using Gene Expression Omnibus data,including GSE36376 and GSE14520.The 10-year overall survival(OS),progression-free survival(PFS)and relapse-free survival(RFS)rates between high and low ORM expression groups in liver cancer patients were determined using the Kaplan-Meier plotter tool.Gene Set Enrichment Analysis(GSEA)was employed to explore the ORM2-associated signaling network.Correlations between ORM2 expression and tumor purity or the infiltration level of macrophages in liver tumor tissues were determined using the TIMER database.The correlation between ORM2 gene levels,tumor-associated macrophage(TAM)markers(including CD68 and TGFβ1)and T cell immunosuppression(including CTLA4 and PD-1)in liver tumor tissues and liver GTEx was determined using the GEPIA database.RESULTS ORM1 and ORM2 were highly expressed in normal liver and liver tumor tissues.ORM1 and ORM2 expression was significantly decreased in liver tumor tissues compared with adjacent normal tissues,and similar results were also noted in cholangiocarcinoma,esophageal carcinoma,and lung squamous cell carcinoma.Further analysis of the Gene Expression Omnibus Database also confirmed the downregulation of ORM1 and ORM2 in liver tumors.Survival analysis showed that the high ORM2 group had better survival rates in OS,PFS and RFS.ORM1 only represented better performance in PFS,but not in OS or RFS.GSEA analysis of ORM2 from The Cancer Genome Atlas liver cancer data identified that ORM2 positively associated with the G2/M checkpoint,E2F target signaling,as well as Wnt/β-catenin and Hedgehog signaling.Moreover,apoptosis,IFN-αresponses,IFN-γresponses and humoral immune responses were upregulated in the ORM2 high group.ORM2 expression was negatively correlated with the macrophage infiltration level,CD68,TGFβ1,CTLA4 and PD-1 levels.CONCLUSION The results showed that ORM1 and ORM2 were highly expressed specifically in liver tissues,whereas ORM1 and ORM2 were downregulated in liver tumor tissues.ORM2 is a better prognostic factor for liver cancer.Furthermore,ORM2 is closely associated with cancer-promoting pathways.

Enhancement of CD4^+ T cell activities and modulation of Th1/Th2 lineage development in radiated tumor-bearing rats treated with male zooid of Antheraea pernyi extracts

AIM： To investigate whether supplementation of male zooid of Antheraea pernyi extracts （MZAPE） could enhance immune function of radiated tumor-bearing rats. METHODS： Eighty male Wistar rats were randomly divided into a control group, a simple radiation group, a MZAPE group, and a radiation plus MZAPE group. With the tumor model established by implanting Walker-256 ascites tumor cells, tumor weight and tumor control rate were calculated. The rats in the simple radiation and radiation plus MZAPE groups were underwent to radiation at 10 Gy within 2 d. In the MZAPE and radiation plus MZAPE groups, the MZAPE was gavaged at a dose of 16.53 mg/kg once a day for 7 d. T cell subsets in peripheral blood were determined by flow cytometry and the expression of IL-2, IFN-γ, IL-4 and IL-10 in sera were determined by ELISA on the 8th d. RESULTS： The tumor weight of simple radiation group, MZAPE group and radiation plus MZAPE group was lower than that of control group （P 〈 0.01） and tumor control rates were 63.08% ± 6.43%, 69.86%± 7.12% and 35.30% ± 7.67%, respectively. CD^4＋ T and CD^8＋ T cells in the peripheral blood of the simple radiation group were fewer than in control group. In the MZAPE and radiation plus MZAPE groups, the number of CD^4＋ T cells was higher while CD^8＋ T cells was lower than in the control and simple radiation groups. Expression of IL-2 and INF-y in the radiation group was lower than in control group, and significantly enhanced during MZAPE therapy （P 〈 0.05）. Expression of IL-4 and IL-10 in the radiation group had no significant changes compared with the control group, and decreased significantly after MZAPE treatment （P 〈 0.01）. CONCLUSION： MZAPE administration may help improve the immune function of the radiated tumor-bearing rats and reverse the radiation-induced immune inhibition by promoting the proliferation of T helper cells and inducing the transdifferentiation from Th2 to Th1.

Does steroid-free immunosuppression improve the outcome in kidney transplant recipients compared to conventional protocols?

Steroids continue to be the cornerstone of immune suppression since the early days of organ transplantation.Steroids are key component of induction protocols,maintenance therapy and in the treatment of various forms of rejection.Prolonged steroid use resulted in significant side effects on almost all the body organs owing to the presence of steroid receptors in most of the mammalian cells.Kidney allograft recipients had to accept the short and long term complications of steroids because of lack of effective alternatives.This situation changed with the introduction of newer and more effective immune suppression agents with a relatively more acceptable side effect profile.As a result,the clinicians have been contemplating if it is the time to abandon the unquestionable reliance on maintenance steroids in modern transplantation practice.This review aims to evaluate the safety and efficacy of various steroid-minimization approaches(steroid avoidance,early steroid withdrawal,and late steroid withdrawal)in kidney transplant recipients.A meticulous electronic search was conducted through the available data resources like SCOPUS,MEDLINE,and Liverpool University library e-resources.Relevant articles obtained through our search were included.A total number of 90 articles were eligible to be included in this review[34 randomised controlled trials(RCT)and 56 articles of other research modalities].All articles were evaluating the safety and efficacy of various steroidfree approaches in comparison to maintenance steroids.We will cover only the RCT articles in this review.If used in right clinical context,steroid-free protocols proved to be comparable to steroid-based maintenance therapy.The appropriate approach should be tailored individually according to each recipient immunological challenges and clinical condition.

Enhanced CD3^+/CD4^+ T Cell Activities and Modulation of Th1/Th2 Lineage Development in Irradiated Rats Due to Treatment with the Male Zooid of Antheraea Pernyi Extracts

Objective： Cancer patients undergoing large dose radiotherapy exhibit multifaceted defects in their immune capacity that are likely to contribute to an increased susceptibility to infections and disease progression. The immune impairment may also constitute a barrier to effective immunotherapeutic interventions. Here, we evaluate whether supplementation with the male zooid of Antheraea pernyi extracts could enhance immune function in irradiated rats. Methods： Fifty male Wistar rats were randomly divided into a control group, a simple radiation group and a treatment group. The mice in the simple irradiation and treatment groups were given whole-chest irradiation with 6Gy. In the treatment group, the male zooid of Antheraea pernyi extracts was gavaged at the doses of 16.53mg/kg （large dose group）, 2.62mg/kg （medium dose group）, and 0.564mg/kg （small dose group） once a day for 14 days. The thymus and spleen indices were calculated. T cell subsets in peripheral blood were determined by flow cytometry and the expressions of IL-2, IFN-γ, IL-4 and IL-10 in sera were determined by ELISA on the 15th day. Results： The thymus index and spleen index of the high dose treatment group were statistically lower than that of the control group and higher than that of the radiation group （P〈0.01）. CD3＋ and CD4＋ T cells in the peripheral blood were increased in the high dose treatment group and decreased in the radiation group （P〈0.01）. Expression of IL-2 and INF-T in the radiation group was lower than that in control, and significantly increased during therapy. The production of IL-4 and IL-10 could be induced by radiation and was inhibited in the high dose treatment group （P〈0.01）. Conclusion： Our data indicate that the male zooid of Antheraea pernyi extracts may be administrated to improve immune function in irradiated rats and reverse the radial immune inhibition of rats by stimulating the proliferation of Th ceils and inducing the differentiation of Th2 to Th1.

Prevalence of diverticulosis in recurrent Clostridium difficile infection

AIM:To re-evaluate the theory that colonic diverticulosis is associated with relapse of Clostridium difficile associated disease (CDAD) in light of data suggesting increasing rates of CDAD infection and relapse.METHODS: Charts were reviewed for patients with recurrent CDAD who had also had a prior colonoscopy or flexible sigmoidoscopy. An age and gender matched control group was used to compare the prevalence of diverticulosis.RESULTS: Twenty-two patients met the study criteria, and the prevalence of diverticulosis in patients with CDAD relapse was 23% compared to 32% in age and sex matched controls (P=0.44). A significant proportion of patients with CDAD relapse had comorbidities associated with immune suppression.CONCLUSION: Diverticulosis does not appear to be associated with CDAD relapse.

The inhibitory effect of adenosine on tumor adaptive immunity and intervention strategies

Adenosine(Ado)is significantly elevated in the tumor microenvironment(TME)compared to normal tissues.It binds to adenosine receptors(AdoRs),suppressing tumor antigen presentation and immune cell activation,thereby inhibiting tumor adaptive immunity.Ado downregulates major histocompatibility complex II(MHC II)and co-stimulatory factors on dendritic cells(DCs)and macrophages,inhibiting antigen presentation.It suppresses anti-tumor cytokine secretion and T cell activation by disrupting T cell receptor(TCR)binding and signal transduction.Ado also inhibits chemokine secretion and KCa3.1 channel activity,impeding effector T cell trafficking and infiltration into the tumor site.Furthermore,Ado diminishes T cell cytotoxicity against tumor cells by promoting immune-suppressive cytokine secretion,upregulating immune checkpoint proteins,and enhancing immune-suppressive cell activity.Reducing Ado production in the TME can significantly enhance anti-tumor immune responses and improve the efficacy of other immunotherapies.Preclinical and clinical development of inhibitors targeting Ado generation or AdoRs is underway.Therefore,this article will summarize and analyze the inhibitory effects and molecular mechanisms of Ado on tumor adaptive immunity,as well as provide an overview of the latest advancements in targeting Ado pathways in anti-tumor immune responses.

The processed C-terminus of AvrRps4 effector suppresses plant immunity via targeting multiple WRKYs

Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.

Contribution of myeloid-derived suppressor cells to tumor-induced immune suppression,angiogenesis,invasion and metastasis

Growing evidence suggests that myeloid-derived suppressor cells （MDSCs）,which have been named ＂immature myeloid cells＂ or ＂myeloid suppressor cells＂ （MSCs）,play a critical role during the progression of cancer in tumor-bearing mice and cancer patients.As their name implies,these cells are derived from bone marrow and have a tremendous potential to suppress immune responses.Recent studies indicated that these cells also have a crucial role in tumor progression.MDSCs can directly incorporate into tumor endothelium.They secret many pro-angiogenic factors as well.In addition,they play an essential role in cancer invasion and metastasis through inducing the production of matrix metalloproteinases （MMPs）,chemoattractants and creating a pre-metastatic environment.Increasing evidence supports the idea that cancer stem cells （CSCs） are responsible for tumorigenesis,resistance to therapies,invasion and metastasis.Here,we hypothesize that CSCs may ＂hijack＂ MDSCs for use as alternative niche cells,leading to the maintenance of stemness and enhanced chemo-and radio-therapy resistance.The countermeasure that directly targets to MDSCs may be useful for against angiogenesis and preventing cancer from invasion and metastasis.Therefore,the study of MDSCs is important to understand tumor progression and to enhance the therapeutic efficacy against cancer.

Intercellular Trogocytosis Plays an Important Role in Modulation of Immune Responses

Intercellular communication is an important means of molecular information transfer through exchange of membrane proteins from cells to cells. Advent of the latest analytical and imaging tools has allowed us to enhance our understanding of the cellular communication through the intercellular exchange of intact membrane patches, also called trogocytosis, which is a ubiquitous phenomenon. Immune responses against pathogens or any foreign antigens require fine immune regulation, where cellular communications are mediated by either soluble or cell surface molecules. It has been demonstrated that the membrane molecule transfer between immune cells such as dendritic and T cells can be derived through internalization/recycling pathway, dissociation-associated pathway, uptake of exosomes and membrane nanotube formations. Recent evidence implicates the trogocytosis as an important mechanism of the immune system to modulate immune responses. Exchange of membrane molecules/ antigens between immune cells has been observed for a long time, but the mechanisms and functional consequences of these transfers remain unclear. In this review, we discuss the possible mechanisms of trogocytosis and its physiological relevance to immune system, with special reference to T cells and the stimulatory or suppressive immune responses derived from T cells with acquired dendritic cell membrane molecules. Cellular ＆ Molecular Immunology. 2008;5（4）：261-269.