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

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

Circulating myeloid-derived suppressor cells in patients with pancreatic cancer

BACKGROUND： Myeloid-derived suppressor cells （MDSCs） are heterogeneous cell types that suppress T-cell responses in cancer patients and animal models, some MDSC subpopulations are increased in patients with pancreatic cancer. The present study was to investigate a specific subset of MDSCs in patients with pancreatic cancer and the mechanism of MDSCs increase in these patients. METHODS： Myeloid cells from whole blood were collected from 37 patients with pancreatic cancer, 17 with cholangiocarcinoma, and 47 healthy controls. Four pancreatic cancer cell lines were co- cultured with normal peripheral blood mononudear cells （PBMCs） to test the effect of tumor cells on the conversion of PBMCs to MDSCs. Levels of granulocyte-macrophage colony-stimulating factor （GM-CSF） and arginase activity in the plasma of cancer patients were analyzed by enzyme-linked immunosorbent assay. RESULTS： CD14＋/CD11b＋/HLA-DR MDSCs were increased in patients with pancreatic or bile duct cancer compared with those in healthy controls, and this increase was correlated with clinical cancer stage. Pancreatic cancer cell lines induced PBMCs to MDSCs in a dose-dependent manner. GM-CSF and arginase activity levels were significantly increased in the se rum of patients with pancreatic cancer. CONCLUSIONS： MDSCs were tumor related： tumor cells induced PBMCs to MDSCs in a dose-dependent manner and circulating CD14＋/CD11b＋/HLA-DR- MDSCs in pancreatic cancer patients were positively correlated with tumor burden. MDSCs might be useful markers for pancreatic cancer detection and progression.

NEDD9 promotes cancer stemness by recruiting myeloid-derived suppressor cells via CXCL8 in esophageal squamous cell carcinoma

Objective:Esophageal squamous cell carcinoma(ESCC)has high morbidity and mortality rates worldwide.Cancer stem cells(CSCs)may cause tumor initiation,metastasis,and recurrence and are also responsible for chemotherapy and radiotherapy failures.Myeloid-derived suppressor cells(MDSCs),in contrast,are known to be involved in mediating immunosuppression.Here,we aimed to investigate the mechanisms of interaction of CSCs and MDSCs in the tumor microenvironment.Methods:ESCC tissues and cell lines were evaluated.Neural precursor cell expressed,developmentally downregulated 9(NEDD9)was knocked down and overexpressed by lentiviral transfection.Quantitative PCR,Western blot,immunohistochemistry,cell invasion,flow cytometry,cell sorting,multiplex chemokine profiling,and tumor growth analyses were performed.Results:Microarray analysis revealed 10 upregulated genes in esophageal CSCs.Only NEDD9 was upregulated in CSCs using the sphere-forming method.NEDD9 expression was correlated with tumor invasion(P=0.0218),differentiation(P=0.0153),and poor prognosis(P=0.0373).Additionally,NEDD9 was required to maintain the stem-like phenotype.Screening of chemokine expression in ESCC cells with NEDD9 overexpression and knockdown showed that NEDD9 regulated C-X-C motif chemokine ligand 8(CXCL8)expression via the ERK pathway.CXCL8 mediated the recruitment of MDSCs induced by NEDD9 in vitro and in vivo.MDSCs promoted the stemness of ESCC cells through NEDD9 via the Notch pathway.Conclusions:As a marker of ESCC,NEDD9 maintained the stemness of ESCC cells and regulated CXCL8 through the ERK pathway to recruit MDSCs into the tumor,suggesting NEDD9 as a therapeutic target and novel prognostic marker for ESCC.

Role of myeloid-derived suppressor cells in autoimmune disease

Myeloid-derived suppressor cells(MDSCs) represent an important class of immunoregulatory cells that can be activated to suppress T cell functions. These MDSCs can inhibit T cell functions through cell surface interactions and the release of soluble mediators. MDSCs accumulate in the inflamed tissues and lymphoid organs of patients with autoimmune diseases. Much of our knowledge of MDSC function has come from studies involving cancer models, however many recent studies have helped to characterize MDSC involvement in autoimmune diseases. MDSCs are a heterogeneous group of immature myeloid cells with a number of different functions for the suppression of T cell responses. However, we have yet to fully understand their contributions to the development and regulation of autoimmune diseases. A number of studies have described beneficial functions of MDSCs during autoimmune diseases, and thus there appears to be a potential role for MDSCs in the treatment of these diseases. Nevertheless, many questions remain as to the activation, differentiation, and inhibitory functions of MDSCs. This review aims to summarize our current knowledge of MDSC subsets and suppressive functions in tissue-specific autoimmune disorders. We also describe the potential of MDSC-basedcell therapy for the treatment of autoimmune diseases and note some of hurdles facing the implementation of this therapy.

Changes in the frequency of myeloid-derived suppressor cells after transarterial chemoembolization with gelatin sponge microparticles for hepatocellular carcinoma

Purpose: A series of clinical studies have established the safety and efficacy of transcatheter arterial chemoembolization(TACE) with gelatin sponge microparticles(GSMs) in treating hepatocellular carcinoma(HCC). HCC can lead to obvious necrosis inside tumors, especially larger ones, although it is unclear whether such necrotic tumor tissue can induce favorable immune reactions against the tumor. Myeloid-derived suppressor cells(MDSCs)have immunosuppressive functions and are currently considered a very important cell type affecting tumor immunity. This study observed changes in MDSC frequency in peripheral blood before and after GSM–TACE to evaluate the effect on the immune function of HCC patients.Methods: Eight patients diagnosed with HCC underwent GSM–TACE treatment in the Hepatobiliary Interventional Department of Beijing Tsinghua Chang Gung Hospital, Beijing, China;we followed up with the patients over a period of 30 days post-surgery. We used flow cytometry(FCM) to quantify the frequency of MDSCs in peripheral blood before TACE, 10 days after surgery and 30 days after surgery.Results: MDSC frequency after GSM–TACE had a significant downward trend. Pre-TACE, it was 30.73% ? 11.93%,decreasing to 18.60% ? 11.37% at 10 days after operation. This decrease was not statistically significant(P > 0.05). MDSC frequency was even lower 30 days after TACE(7.63% ? 7.32%) than at 10 days after TACE(P < 0.05), and there was a significant difference compared with pre-TACE(P < 0.001). We evaluated tumor response at 30 days after GSM–TACE according to the Modified Response Evaluation Criteria in Solid Tumors(mRECIST), and all eight patients showed partial response(PR).Conclusion: Our results confirmed that GSM–TACE was beneficial for improving anti-tumor immunity in the treatment of HCC.

Cyclooxygenase-2 Blockade Inhibits Accumulation and Function of Myeloid-derived Suppressor Cells and Restores T Cell Response after Traumatic Stress

Myeloid-derived suppressor cells （MDSCs） play a crucial role in T cell dysfunction, which is related to poor outcome in patients with severe trauma. Cyclooxygenase-2 （Cox-2） contributes to immune disorder in trauma and infection via production of prostaglandin E2. However, the role of Cox-2 in the accumulation and function of MDSCs after traumatic stress has not been fully elucidated. In the present study, we treated murine trauma model with NS398, a selective Cox-2 inhibitor. Then the percentages of CD1 lb＋/Gr-l＋ cells, proliferation and apoptosis of CD4＋ T cells were determined. Ar- ginase activity and arginase-1 （Arg-1） protein expression of splenic CDllb＋/Gr-I＋ cells, and de- layed-type hypersensitivity （DTH） response were analyzed. The results showed that Cox-2 blockade significantly decreased the percentages of CD1 lb＋/Gr-l＋ cells in the spleen and bone marrow 48 and 72 h after traumatic stress. NS398 inhibited arginase activity and down-regulated the Arg-1 expression of splenic CD1 lb＋/Gr-l＋ ceils. Moreover, NS398 could promote proliferation and inhibit apoptosis of CD4＋ T cells. It also restored DTH response of traumatic mice. Taken together, our data revealed that Cox-2 might play a pivotal role in the accumulation and function of MDSC after traumatic stress.

Correlation between circulating myeloid-derived suppressor cells and Th17 cells in esophageal cancer

AIM: To perform a comprehensive investigation into the potential correlation between circulating myeloidderived suppressor cells (MDSCs) and Th17 cells in esophageal cancer (ECA). METHODS: A total of 31 patients newly diagnosed with ECA and 26 healthy subjects were included in the current study. The frequencies of MDSCs and Th17 cells in peripheral blood were determined by flow cytometry. The mRNA expression of cytokines, arginase 1 (Arg1) and inducible NO synthase (iNOS) in peripheral blood mononuclear cells (PBMCs) and plasma Arg1 were assessed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. RESULTS: There was an increased prevalence of MDSCs in the peripheral blood from ECA patients (15.21% ± 2.25%) when compared with healthy control (HC) (1.10% ± 0.12%, P < 0.0001). The plasma levels of Arg1 in ECA patients were significantly higher than those in HC (28.28 ± 4.10 ng/mL vs 9.57 ± 1.51 ng/ mL, P=0.0003). iNOS mRNA levels in the peripheral blood of ECA patients also showed a threefold increase compared with HC (P=0.0162). The frequencies of Th17 cells (CD4 + IL-17A + ) were significantly elevated in ECA patients versus HC (3.50% ± 0.33% vs 1.82% ± 0.19%, P=0.0001). Increased mRNA expression of IL-17 and ROR-γt was also observed in ECA patients compared with HC (P=0.0041 and P=0.0004, respectively), while the mRNA expression of IL-6 and tumor necrosis factor-α (TNF-α) showed significant decreases (P=0.0049 and P < 0.0001, respectively). No obvious correlations were found between the frequencies of MDSCs and Th17 cells in the peripheral blood from ECA patients(r=-0.1725, P=0.3534). Arg1 mRNA levels were positively correlated with levels of IL-6 (r=0.6404, P=0.0031) and TNF-α (r=0.7646, P=0.0001). Similarly, iNOS mRNA levels were also positively correlated with levels of IL-6 (r=0.6782, P=0.0007) and TNF-α (r=0.7633, P < 0.0001). CONCLUSION: This study reveals the relationship between circulating MDSCs and Th17 cells, which may lead to new immunotherapy approaches for ECA based on the associated metabolites and cytokines.

Amplification of Functional Myeloid-derived Suppressor Cells during Stem Cell Mobilization Induced by Granulocyte Colony-stimulation-factor

The effects of granulocyte colony-stimulation-factor （G-CSF） on stem cell mobilization and its impact on the amplification of myeloid-derived suppressor cells （MDSCs） of donor mice were ex- amined. A mouse model of stem cell mobilization was established by consecutive subcutaneous injec- tion of 100 μg/kg G-CSF for 5 days. The blood from the donor mice was routinely examined during mobilization. Stem cells and MDSCs were analyzed by flow cytometry. The immunosuppressive mole- cules derived from MDSCs in serum and spleen, including hydrogen dioxide （H202） and nitric oxide （NO）, and the activity of nitric oxide synthase （NOS） were determined during the mobilization. Apop- tosis of T lymphocytes was assessed by using Annexin-V/PI. During stem cell mobilization, the number of lymphocytes and white blood cells in the peripheral blood was increased, and peaked on the 4th day. The number of stem cells in G-CSF-treated mice was significantly greater than that in controls （P〈0.01）. The expansions of MSDCs were also observed after G-CSF mobilization, with a more notable rate of growth in the peripheral blood than in the spleen. The activity of NOS and the production of NO were increased in the donor mice, and the serum H202 levels were approximately 4-fold greater than the con- trois. Consequently, apoptosis of T lymphocytes was increased and showed a positive correlation with the elevated percentage of MDSCs. It was concluded that G-CSF could provide sufficient peripheral blood stem cells for transplantation. Exogenous administration of G-CSF caused the accumulation of MDSCs in the peripheral blood and the spleen, which could lead to apoptosis ofT lymphocytes and may offer a new strategy for the prevention and treatment of graft versus host disease.

Myeloid-derived Suppressor Cells Activate Liver Natural Killer Cells in a Murine Model in Uveal Melanoma

Objective Elevated myeloid-derived suppressor cells(MDSCs)in many malignancies are associated with the increased risk for metastases and poor prognosis.Therefore,a mouse model of intraocular melanoma was established to explore how MDSCs influence liver metastases.Methods In this study,murine B16LS melanoma cells were transplanted into the posterior compartment(PC)of the eye of C57BL/6 mice.Leucocytes from the liver of naive mice and mice bearing melanoma liver metastasis were isolated using isotonic Percoll centrifugation,examined by flow cytometry for their expression of Gr1,CD11b,F4/80,RAE-1,and Mult-1,and further isolated for MDSCs and natural killer(NK)cells.The effects of MDSCs on NK cells were tested by coculturing and assessing the ability of NK cells to produce interferon-gamma(IFN-γ)by ELISA and NK cell cytotoxicity by 3H-thymidine incorporation assay.The impact of IFN-γon liver metastases was examined via selectively depleting IFN-γin vivo.Results The results showed that mice with liver metastases had increased levels of CD11b+Gr1+F4/80+as well as CD11b+Gr1+F4/80−MDSCs.MDSCs significantly enhanced the generation of IFN-γtogether with the cytotoxicity of the NK cells.Furthermore,these effects were cell-cell contact-dependent.Although IFN-γwas not of a toxic nature to the melanoma cells,it profoundly inhibited B16LS cell proliferation.Depleting IFN-γin vivo led to increased liver metastases.Conclusion All these findings first revealed that MDSCs accumulated in liver metastasis of intraocular melanoma could activate the NK cells to produce an effective anti-tumor immune response.Thus,the MDSCs’performance in different tumor models would need more investigation to boost current immunotherapy modalities.

Myeloid-derived suppressor cells in gastrointestinal cancers:A systemic review

Gastrointestinal(GI)cancers are one of the most common malignancies worldwide,with high rates of morbidity and mortality.Myeloid-derived suppressor cells(MDSCs)are major components of the tumor microenvironment(TME).MDSCs facilitate the transformation of premalignant cells and play roles in tumor growth and metastasis.Moreover,in patients with GI malignancies,MDSCs can lead to the suppression of T cells and natural killer cells.Accordingly,a better understanding of the role and mechanism of action of MDSCs in the TME will aid in the development of novel immune-targeted therapies.

GM3-containing nanoparticles in immunosuppressed hosts:Effect on myeloid-derived suppressor cells

Cancer vaccines to date have not broadly achieved a significant impact on the overall survival of patients. The negative effect on the immune system of the tu-mor itself and conventional anti-tumor treatments such as chemotherapy is, undoubtedly, a key reason for these disappointing results. Myeloid-derived suppres-sor cells （MDSCs） are considered a central node of the immunosuppressive network associated with tumors. These cells inhibit the effector function of natural killer and CD8＋ T cells, expand regulatory T cells and can differentiate into tumor-associated macrophages within the tumor microenvironment. Thus, overcoming the suppressive effects of MDSCs is likely to be criti-cal for cancer immunotherapy to generate effective anti-tumor immune responses. However, the capacity of cancer vaccines and particularly their adjuvants to overcome this inhibitory population has not been well characterized. Very small size proteoliposomes （VSSP） is a nanoparticulated adjuvant specifcally designed to be formulated with vaccines used in the treatment of immunocompromised patients. This adjuvant contains immunostimulatory bacterial signals together with GM3 ganglioside. VSSP promotes dendritic cell maturation, antigen cross-presentation to CD8＋ T cells, Th1 polar-ization, and enhances CD8＋ T cell response in tumor-free mice. Currently, four cancer vaccines using VSSP as the adjuvant are in Phase？Ⅰ？and Ⅱ clinical trials. In this review, we summarize our work characterizing the unique ability of VSSP to stimulate antigen-specifc CD8＋ T cell responses in two immunocompromised sce-narios; in tumor-bearing mice and during chemother-apy-induced leukopenia. Particular emphasis has been placed on the interaction of these nanoparticles with MDSCs, as well as comparison with other cancer vac-cine adjuvants currently in preclinical or clinical studies.

ILC2和MDSC及其相关细胞因子IL-13和iNOS在宫颈癌中的表达及其列线图模型的构建和评价

目的:研究2型固有淋巴样细胞(ILC2)和髓源性抑制细胞(MDSC)及其相关细胞因子IL-13和诱导型一氧化氮合酶(iNOS)在宫颈癌(CC)中的表达,并基于其构建CC发病风险的列线图预测模型。方法:采集2022年5月至2024年1月在新疆医科大学第一附属医院手术切除的40例CC组织及100例外周血作为CC组,选取同期收治的30例子宫肌瘤经CC筛查为阴性的宫颈组织和100例正常健康个体外周血作为对照组。用多重免疫荧光技术(mIF)及免疫组化染色(IHC)法检测两组组织中ILC2和MDSC细胞浸润及其相关细胞因IL-13和iNOS的表达;使用流式细胞术和ELISA技术分别检测两组外周血中ILC2和MDSC及IL-13和iNOS的表达差异;通过Person相关性分析评估其相关性;使用单因素和多因素Logistic分析来确定ILC2和MDSC及IL-13和iNOS是否为CC发病的独立危险因素,再利用R软件建立免疫预测模型,使用ROC曲线下面积(AUC值)、Hosmer-Lemeshow检验、校准曲线、临床决策曲线和临床影响曲线来分别评估模型。结果:CC组中ILC2及MDSC及其相关细胞因子IL-13和iNOS均高于对照组(均P<0.05),且其均呈正相关(均P<0.05);经过单因素及多因素Logistic回归分析显示,ILC2、MDSC及IL-13、iNOS均是CC发病的独立危险因素(均P<0.05);基于这些危险因素的CC发病列线图,经过验证提示,该列线图模型具有一定的临床实用价值。结论:ILC2和MDSC及其相关的细胞因子IL-13和iNOS在CC组织及外周血中均呈高表达,基于这些危险因素构建的预测模型具有良好的预测能力和一定的实用性,为CC的早期诊断和治疗提供了一种简便有效的辅助工具。

MDSCs调控新生儿免疫应答机制及其临床意义

新生儿期的免疫系统发育阶段对维持新生儿健康至关重要,具有独特的免疫调节机制。近年来,人们越来越关注髓源性抑制细胞(MDSCs)在新生儿免疫调节中的作用。MDSCs是一类免疫抑制功能强大的异质性细胞群体,它们能够通过多种机制调节免疫应答。MDSCs在新生儿中的调节作用对防止过度免疫反应和促进免疫耐受至关重要,有助于预防新生儿期炎症性疾病,并对其后续健康产生积极影响。近期研究文献分析展示了MDSCs在新生儿免疫调节中的多种作用机制,包括在特定病理条件下的保护作用、与新生儿期炎症反应的相互作用,以及对长期免疫发展的潜在影响。因此,深入理解MDSCs在新生儿免疫中的角色,不仅有助于揭示其复杂的调节机制,也为制定新的预防和治疗新生儿炎症性疾病的策略提供了新的思路。

Intermittent fasting boosts antitumor immunity by restricting CD11b^(+)Ly6C^(low)Ly6G^(low) cell viability through glucose metabolism in murine breast tumor model

Intermittent fasting can benefit breast cancer patients undergoing chemotherapy or immunotherapy.However,it is still uncertain how to select immunotherapy drugs to combine with intermittent fasting.Herein we observed that two cycles of fasting treatment significantly inhibited breast tumor growth and lung tissue metastasis,as well as prolonged overall survival in mice bearing 4T1 and 4T07 breast cancer.During this process,both the immunosuppressive monocytic-(M-)and granulocytic-(G-)myeloid-derived suppressor cell(MDSC)decreased,accompanied by an increase in interleukin(IL)7R^(+)and granzyme B^(+)T cells in the tumor microenvironment.Interestingly,we observed that Ly6G^(low)G-MDSC sharply decreased after fasting treatment,and the cell surface markers and protein mass spectrometry data showed potential therapeutic targets.Mechanistic investigation revealed that glucose metabolism restriction suppressed the splenic granulocytemonocyte progenitor and the generation of colony-stimulating factors and IL-6,which both contributed to the accumulation of G-MDSC.On the other hand,glucose metabolism restriction can directly induce the apoptosis of Ly6G^(low)G-MDSC,but not Ly6G^(high)subsets.In summary,these results suggest that glucose metabolism restriction induced by fasting treatment attenuates the immune-suppressive milieu and enhances the activation of CD3^(+)T cells,providing potential solutions for enhancing immune-based cancer interventions.

Increased frequency and clinical significance of myeloidderived suppressor cells in human colorectal carcinoma

AIM： To investigate the frequency and clinical signifi- cance of the myeloid-derived suppressor cells （MDSC） in human colorectal carcinoma （CRC）. METHODS： Samples of peripheral blood and tumor tis- sue from 49 CRC patients were analyzed. Mononuclear cells were isolated by FicolI-Hypaque density gradient centrifugation and were subjected to a flow cytometry- based immunophenotypic analysis. RESULTS： A considerable increase in the percentage of CD33＋HLA-DR MDSCs was observed in the periph- eral blood （1.89% ：1= 0.75%） and tumor tissues （2.99%±1.29%） of CRC patients as compared with that in theperipheral blood of healthy controls （0.54%±0.35%）. This expanded CD33＋HLA-DR subset exhibited imma- ture myeloid cell markers, but not lineage markers, and showed up-regulation of CD18/CD11b expression as compared with the MDSCs from healthy donors. Fur- ther studies showed that the MDSC proportion in CRC peripheral blood was correlated with nodal metastasis （P = 0.023）, whereas that in tumor tissues was cor- related with nodal/distant metastasis （P = 0.016/P = 0.047） and tumor stage （P = 0.028）, suggesting the involvement of MDSCs in CRC tumor development. CONCLUSION： Characterization of MDSCs in CRC sug- gests the clinical significance of circulating and tumor- infiltrating MDSCs and may provide new insights into the CRC immunotherapy targeting MDSCs.

Single-cell transcriptome profiling of sepsis identifies HLA-DR^(low)S100A^(high)monocytes with immunosuppressive function

Background Sustained yet intractable immunosuppression is commonly observed in septic patients,resulting in aggravated clinical outcomes.However,due to the substantial heterogeneity within septic patients,precise indicators in deciphering clinical trajectories and immunological alterations for septic patients remain largely lacking.Methods We adopted cross-species,single-cell RNA sequencing(scRNA-seq)analysis based on two published datasets containing circulating immune cell profile of septic patients as well as immune cell atlas of murine model of sepsis.Flow cytometry,laser scanning confocal microscopy(LSCM)imaging and Western blotting were applied to identify the presence of S100A9^(+)monocytes at protein level.To interrogate the immunosuppressive function of this subset,splenic monocytes isolated from septic wild-type or S100a9^(–/–)mice were co-cultured with naive CD4^(+)T cells,followed by proliferative assay.Pharmacological inhibition of S100A9 was implemented using Paquinimod via oral gavage.Results scRNA-seq analysis of human sepsis revealed substantial heterogeneity in monocyte compartments following the onset of sepsis,for which distinct monocyte subsets were enriched in disparate subclusters of septic patients.We identified a unique monocyte subset characterized by high expression of S100A family genes and low expression of human leukocyte antigen DR(HLA-DR),which were prominently enriched in septic patients and might exert immunosuppressive function.By combining single-cell transcriptomics of murine model of sepsis with in vivo experiments,we uncovered a similar subtype of monocyte significantly associated with late sepsis and immunocompromised status of septic mice,corresponding to HLA-DR^(low)S100A^(high)monocytes in human sepsis.Moreover,we found that S100A9^(+)monocytes exhibited profound immunosuppressive function on CD4^(+)T cell immune response and blockade of S100A9 using Paquinimod could partially reverse sepsis-induced immunosuppression.Conclusions This study identifies HLA-DR^(low)S100A^(high)monocytes correlated with immunosuppressive state upon septic challenge,inhibition of which can markedly mitigate sepsis-induced immune depression,thereby providing a novel therapeutic strategy for the management of sepsis.

ACAT1 deficiency in myeloid cells promotes glioblastoma progression by enhancing the accumulation of myeloid-derived suppressor cells

Glioblastoma(GBM)is a highly aggressive and lethal brain tumor with an immunosuppressive tumor microenvironment(TME).In this environment,myeloid cells,such as myeloid-derived suppressor cells(MDSCs),play a pivotal role in suppressing antitumor immunity.Lipometabolism is closely related to the function of myeloid cells.Here,our study reports that acetyl-CoA acetyltransferase 1(ACAT1),the key enzyme of fatty acid oxidation(FAO)and ketogenesis,is significantly downregulated in the MDSCs infiltrated in GBM patients.To investigate the effects of ACAT1 on myeloid cells,we generated mice with myeloid-specific(LyzM-cre)depletion of ACAT1.The results show that these mice exhibited a remarkable accumulation of MDSCs and increased tumor progression both ectopically and orthotopically.The mechanism behind this effect is elevated secretion of C-X-C motif ligand 1(CXCLI)of macrophages(Mo).Overall,our findings demonstrate that ACAT1 could serve as a promising drug target for GBM by regulating the function of MDSCs in the TME.

MDSC靶向免疫治疗胰腺癌的研究进展

胰腺癌(pancreatic cancer,PC)是一种高度恶性的消化系统肿瘤,生存率低且预后较差。大多数胰腺癌患者在疾病早期均无明显临床表现,发现就诊时已处于疾病中晚期。在其发展演变过程中形成了独特且复杂的肿瘤微环境(tumor microenvironment,TME)。由于胰腺癌发病的隐匿性,针对于胰腺癌中晚期患者,仅靠一些传统治疗手段比如手术切除,化疗等显得十分局限,目前缺乏有效的治疗方案。当然,这也与胰腺癌的TME的免疫抑制性有关。一些免疫抑制性细胞,如骨髓源性抑制细胞(myeloid-derived suppressor cells,MDSCs)、调节性T细胞(T-regulatory cells,Treg细胞)等在帮助肿瘤免疫逃逸方面发挥着重要的免疫抑制作用。因此,被认为是治疗胰腺癌的一大难点。近年来,随着对TME的深入研究,免疫治疗也逐渐作为一种新的治疗策略,在多种恶性肿瘤的治疗中取得重大进展。研究发现,靶向MDSC疗法是一种新的且有效的胰腺癌治疗方法。该文就MDSC在TME中发挥的作用及其作为潜在靶点免疫治疗胰腺癌的相关进展进行介绍,以期为胰腺癌等肿瘤的治疗提供新方向。

髓源性抑制细胞在多发性骨髓瘤中的研究进展

多发性骨髓瘤(multiple myeloma,MM)是浆细胞恶性增殖性疾病,目前为血液系统第二大肿瘤。虽然蛋白酶体抑制剂和免疫治疗方案的应用改善了MM患者的预后,但大多数仍然无法被治愈,主要是因为MM细胞最终产生耐药。髓源性抑制细胞(myeloid-derived suppressor cells,MDSCs)是骨髓中髓系祖细胞分化受阻而形成的具有显著抑制T细胞免疫应答功能的一群异质性细胞,通过介导免疫抑制性作用促进MM的发展。MDSCs还刺激MM细胞增殖,诱导MM耐药和转移。本文综述了MDSCs在MM发生、发展中表现的多种机制,并探讨针对MDSCs的治疗策略在MM中的可行性及挑战,以期为MM治疗提供参考。

MDSCs与肿瘤免疫逃逸

髓源抑制性细胞(myeloid-derived suppressor cells,MDSCs)是一群异质性细胞,来源于骨髓祖细胞和未成熟髓细胞(immature myeloid cells,IMCs),是树突状细胞(dendritic cells,DCs)、巨噬细胞和(或)粒细胞的前体。在荷瘤小鼠的血液、脾脏和肿瘤组织及肿瘤患者的外周血和肿瘤组织存在大量MDSCs的扩增。MDSCs可以通过多种途径抑制机体的获得性和天然抗肿瘤免疫,使肿瘤细胞逃避机体的免疫监视和攻击,促进肿瘤发展。MDSCs首先从骨髓募集到外周,并在外周被激活后才能发挥抗肿瘤免疫抑制功能,肿瘤来源的慢性炎症相关的一系列因子在介导MDSCs的募集和活化中起关键作用。当前靶向MDSCs的抗肿瘤治疗取得了一定的进展,但MDSCs从发现到现在仅仅经历了10年左右的时间,该领域中许多的未知尚需要大量的基础和临床研究来阐明。本文主要介绍MDSCs的特征及其亚群、MDSCs的募集和活化、MDSCs介导免疫逃逸的机制及当前靶向MDSCs的抗肿瘤治疗策略,以期为从事该领域的研究工作者提供参考。